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Sample records for biofilm forming ability

  1. STUDY OF ULTRASOUND RADIATION INFLUENCE ON ABILITY TO FORM BIOFILMS AND FORMED BIOFILMS OF KLEBSIELLA PNEUMONIAE

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    Mozgova Yu.A.

    2013-01-01

    With aim to detect ability to form biofilms in K.pneumoniae and to study effects of low-intensity ultrasound radiation on formed biofilms and their aggregation microbiological research of material frompatients with pyoinflammatory diseases was performed. It was found that low-intensity ultrasound radiation could destroy formed biofilms of K. pneumoniae and decrease ability of this pathogen to form secondary biofilms.

  2. EFFECT OF ULTRASOUND RADIATION ON FORMED BIOFILMS AND ABILITY TO THEIR FORMATION IN S.AUREUS

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    Mishina M.M.

    2013-01-01

    Microbiological research of the clinical material receivedfrom with inflammatory processes was carried on that todetect ability to form biofilms and to study effect of low-intensity ultrasound radiation on formed biofilms and theiraggregation ability. Performed research showed that ultrasound radiation of low intensity could destroy biofilms and inhibit ability of microorganisms to form secondary biofilms.

  3. ENTEROCOCCI AND THEIR ABILITY TO FORM A BIOFILM

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    Jana Bezeková

    2012-04-01

    Full Text Available Normal 0 21 false false false SK X-NONE X-NONE Number of enterococci determined in raw milk cistern samples was in range of 2.95 to 4.18 log CFU.ml-1 and raw milk samples obtained from storage tanks contained enterococci count in the range of 3.04 to 4.51 log CFU.ml-1. Results of microbiological quality evaluation showed, that count of enterococci increased during cold storage of raw milk. Portion of enterococci from the total microflora of raw milk taken from cistern samples was 0.44 %, otherwise in raw milk samples taken from storage tanks portion of enterococci decreased to 0.38 %. Among enterococci isolates  E. faecalis was the predominat species in tested samples of raw milk from both cistern – 58.1 % and storage tank – 71.7 %. The following species were identified E. faecium, E. group III., E. mundtii, E. casseliflavus. It was found that 38 % E. faecalis isolates were able to form a biofilm.doi:10.5219/200 800x600 Normal 0 21 false false false SK X-NONE X-NONE MicrosoftInternetExplorer4

  4. Pseudomonas aeruginosa Cystic Fibrosis isolates of similar RAPD genotype exhibit diversity in biofilm forming ability in vitro

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    Elborn Stuart J

    2010-02-01

    Full Text Available Abstract Background Pseudomonas aeruginosa is considered to grow in a biofilm in cystic fibrosis (CF chronic lung infections. Bacterial cell motility is one of the main factors that have been connected with P. aeruginosa adherence to both biotic and abiotic surfaces. In this investigation, we employed molecular and microscopic methods to determine the presence or absence of motility in P. aeruginosa CF isolates, and statistically correlated this with their biofilm forming ability in vitro. Results Our investigations revealed a wide diversity in the production, architecture and control of biofilm formation. Of 96 isolates, 49% possessed swimming motility, 27% twitching and 52% swarming motility, while 47% were non-motile. Microtitre plate assays for biofilm formation showed a range of biofilm formation ability from biofilm deficient phenotypes to those that formed very thick biofilms. A comparison of the motility and adherence properties of individual strains demonstrated that the presence of swimming and twitching motility positively affected biofilm biomass. Crucially, however, motility was not an absolute requirement for biofilm formation, as 30 non-motile isolates actually formed thick biofilms, and three motile isolates that had both flagella and type IV pili attached only weakly. In addition, CLSM analysis showed that biofilm-forming strains of P. aeruginosa were in fact capable of entrapping non-biofilm forming strains, such that these 'non-biofilm forming' cells could be observed as part of the mature biofilm architecture. Conclusions Clinical isolates that do not produce biofilms in the laboratory must have the ability to survive in the patient lung. We propose that a synergy exists between isolates in vivo, which allows "non biofilm-forming" isolates to be incorporated into the biofilm. Therefore, there is the potential for strains that are apparently non-biofilm forming in vitro to participate in biofilm-mediated pathogenesis in the CF

  5. Biofilm forming abilities of Salmonella are correlated with persistence in fish meal- and feed factories

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    Heir Even

    2009-05-01

    Full Text Available Abstract Background Feed contaminated with Salmonella spp. constitutes a risk of Salmonella infections in animals, and subsequently in the consumers of animal products. Salmonella are occasionally isolated from the feed factory environment and some clones of Salmonella persist in the factory environment for several years. One hypothesis is that biofilm formation facilitates persistence by protecting bacteria against environmental stress, e.g. disinfection. The aim of this study was to investigate the biofilm forming potential of Salmonella strains from feed- and fishmeal factories. The study included 111 Salmonella strains isolated from Norwegian feed and fish meal factories in the period 1991–2006 of serovar Agona, serovar Montevideo, serovar Senftenberg and serovar Typhimurium. Results Significant differences were found between serovars regarding the abilities to form biofilm on polystyrene (microtiter plate assay and in the air-liquid interface of nutrient broth (pellicle assay. Strains of serovar Agona and serovar Montevideo were good biofilm producers. In Norwegian factories, clones of these serovars have been observed to persist for several years. Most serovar Senftenberg clones appear to persist for a shorter period, and strains of this serovar were medium biofilm producers in our test systems. Strains of the serovar Typhimurium were relatively poor biofilm producers. Salmonella ser. Typhimurium clones have not been observed to persist even though this serovar is resident in Norwegian wild life. When classifying strains according to persistence or presumed non-persistence, persistent strains produced more biofilm than presumed non-persisting strains. Conclusion The results indicate a correlation between persistence and biofilm formation which suggests that biofilm forming ability may be an important factor for persistence of Salmonella in the factory environment.

  6. Marine bacteria from the French Atlantic coast displaying high forming-biofilm abilities and different biofilm 3D architectures

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    Doghri, Ibtissem; Rodrigues, Sophie; Bazire, Alexis; Dufour, Alain; Akbar, David; Sopena, Valérie; Sablé, Sophie; Lanneluc, Isabelle

    2015-01-01

    Background Few studies have reported the species composition of bacterial communities in marine biofilms formed on natural or on man-made existing structures. In particular, the roles and surface specificities of primary colonizers are largely unknown for most surface types. The aim of this study was to obtain potentially pioneering bacterial strains with high forming-biofilm abilities from two kinds of marine biofilms, collected from two different surfaces of the French Atlantic coast: an in...

  7. Staphylococcus aureus Clinical Isolates: Antibiotic Susceptibility, Molecular Characteristics, and Ability to Form Biofilm

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    N. Indrawattana

    2013-01-01

    Full Text Available Periodic monitoring of Staphylococcus aureus characteristics in a locality is imperative as their drug-resistant variants cause treatment problem. In this study, antibiograms, prevalence of toxin genes (sea-see, seg-ser, seu, tsst-1, eta, etb, and etd, PFGE types, accessory gene regulator (agr groups, and ability to form biofilm of 92 S. aureus Thailand clinical isolates were investigated. They were classified into 10 drug groups: groups 1–7 (56 isolates were methicillin resistant (MRSA and 8–10 (36 isolates were methicillin sensitive (MSSA. One isolate did not have any toxin gene, 4 isolates carried one toxin gene (seq, and 87 isolates had two or more toxin genes. No isolate had see, etb, or tsst-1; six isolates had eta or etd. Combined seg-sei-sem-sen-seo of the highly prevalent egc locus was 26.1%. The seb, sec, sel, seu, and eta associated significantly with MSSA; sek was more in MRSA. The sek-seq association was 52.17% while combined sed-sej was not found. Twenty-three PFGE types were revealed, no association of toxin genes with PFGE types. All four agr groups were present; agr group 1 was predominant (58.70% but agr group 2 strains carried more toxin genes and were more frequent toxin producers. Biofilm formation was found in 72.83% of the isolates but there was no association with antibiograms. This study provides insight information on molecular and phenotypic markers of Thailand S. aureus clinical isolates which should be useful for future active surveillance that aimed to control a spread of existing antimicrobial resistant bacteria and early recognition of a newly emerged variant.

  8. [Investigation of the correlation between biofilm forming ability of urinary Candida isolates with the use of urinary catheters and change of antifungal susceptibility in the presence of biofilm].

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    Aslan, Hacer; Gülmez, Dolunay

    2016-04-01

    Frequency of Candida species causing urinary tract infections is increasing, and this increase is outstanding in nosocomial urinary tract infections especially in intensive care units. The ability of biofilm formation that is contributed to the virulence of the yeast, plays a role in the pathogenesis of biomaterial-related infections and also constitutes a risk for treatment failure. The aims of this study were to compare biofilm forming abilities of Candida strains isolated from urine cultures of patients with and without urinary catheters, and to investigate the change of antifungal susceptibility in the presence of biofilm. A total of 50 Candida strains isolated from urine cultures of 25 patients with urinary catheters (10 C.tropicalis, 6 C.glabrata, 4 C.albicans, 4 C.parapsilosis, 1 C.krusei) and 25 without urinary catheters (8 C.tropicalis, 6 C.albicans, 4 C.krusei, 3 C.parapsilosis, 2 C.kefyr, 1 C.glabrata, 1 C.lusitaniae) were included in the study. Biofilm forming ability was tested by Congo red agar (CRA) and microplate XTT [2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide] reduction methods. Fluconazole (FLU) and amphotericin B (AMP-B) susceptibilities of the isolates were determined by reference microdilution method recommended by Clinical and Laboratory Standards Institute for planktonic cells and by XTT reduction assay in case of biofilm presence. Biofilm formation was detected in 12 (24%) by CRA and 50 (100%) of the isolates by XTT reduction method. None of the C.albicans (n= 10) and C.tropicalis (n= 18) strains were detected as biofilm positive by CRA, however, these strains were strongly positive by XTT reduction method. No statistically significant correlation was detected between the presence of urinary catheter and biofilm forming ability of the isolate (p> 0.05). This might be caused by the advantage of biofilm forming strains in adhesion to bladder mucosa at the initial stages of infection. For all of the isolates in

  9. Water-limiting conditions alter the structure and biofilm-forming ability of bacterial multispecies communities in the alfalfa rhizosphere.

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    Pablo Bogino

    Full Text Available Biofilms are microbial communities that adhere to biotic or abiotic surfaces and are enclosed in a protective matrix of extracellular compounds. An important advantage of the biofilm lifestyle for soil bacteria (rhizobacteria is protection against water deprivation (desiccation or osmotic effect. The rhizosphere is a crucial microhabitat for ecological, interactive, and agricultural production processes. The composition and functions of bacterial biofilms in soil microniches are poorly understood. We studied multibacterial communities established as biofilm-like structures in the rhizosphere of Medicago sativa (alfalfa exposed to 3 experimental conditions of water limitation. The whole biofilm-forming ability (WBFA for rhizospheric communities exposed to desiccation was higher than that of communities exposed to saline or nonstressful conditions. A culture-dependent ribotyping analysis indicated that communities exposed to desiccation or saline conditions were more diverse than those under the nonstressful condition. 16S rRNA gene sequencing of selected strains showed that the rhizospheric communities consisted primarily of members of the Actinobacteria and α- and γ-Proteobacteria, regardless of the water-limiting condition. Our findings contribute to improved understanding of the effects of environmental stress factors on plant-bacteria interaction processes and have potential application to agricultural management practices.

  10. Biofilm-Forming Ability of Candida albicans Is Unlikely To Contribute to High Levels of Oral Yeast Carriage in Cases of Human Immunodeficiency Virus Infection

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    Jin, Y.; Yip, H K; Samaranayake, Y. H.; Yau, J. Y.; Samaranayake, L. P.

    2003-01-01

    An increased prevalence of candidal carriage and oral candidiasis is common in cases of human immunodeficiency virus (HIV) infection, and the reasons for this may include the enhanced ability of colonizing yeasts to produce biofilms on mucosal surfaces. The aim of the present study was therefore to examine the differences, if any, in the biofilm-forming abilities of 26 Candida albicans yeast isolates from HIV-infected individuals and 20 isolates from HIV-free individuals, as this attribute of...

  11. Biofilms

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    López, Daniel; Vlamakis, Hera; Kolter, Roberto

    2010-01-01

    The ability to form biofilms is a universal attribute of bacteria. Biofilms are multicellular communities held together by a self-produced extracellular matrix. The mechanisms that different bacteria employ to form biofilms vary, frequently depending on environmental conditions and specific strain attributes. In this review, we emphasize four well-studied model systems to give an overview of how several organisms form biofilms: Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, and ...

  12. The chemical digestion of Ti6Al7Nb scaffolds produced by Selective Laser Melting reduces significantly ability of Pseudomonas aeruginosa to form biofilm.

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    Junka, Adam F; Szymczyk, Patrycja; Secewicz, Anna; Pawlak, Andrzej; Smutnicka, Danuta; Ziółkowski, Grzegorz; Bartoszewicz, Marzenna; Chlebus, Edward

    2016-01-01

    In our previous work we reported the impact of hydrofluoric and nitric acid used for chemical polishing of Ti-6Al-7Nb scaffolds on decrease of the number of Staphylococcus aureus biofilm forming cells. Herein, we tested impact of the aforementioned substances on biofilm of Gram-negative microorganism, Pseudomonas aeruginosa, dangerous pathogen responsible for plethora of implant-related infections. The Ti-6Al-7Nb scaffolds were manufactured using Selective Laser Melting method. Scaffolds were subjected to chemical polishing using a mixture of nitric acid and fluoride or left intact (control group). Pseudomonal biofilm was allowed to form on scaffolds for 24 hours and was removed by mechanical vortex shaking. The number of pseudomonal cells was estimated by means of quantitative culture and Scanning Electron Microscopy. The presence of nitric acid and fluoride on scaffold surfaces was assessed by means of IR and rentgen spetorscopy. Quantitative data were analysed using the Mann-Whitney test (P ≤ 0.05). Our results indicate that application of chemical polishing correlates with significant drop of biofilm-forming pseudomonal cells on the manufactured Ti-6Al-7Nb scaffolds ( p = 0.0133, Mann-Whitney test) compared to the number of biofilm-forming cells on non-polished scaffolds. As X-ray photoelectron spectroscopy revealed the presence of fluoride and nitrogen on the surface of scaffold, we speculate that drop of biofilm forming cells may be caused by biofilm-supressing activity of these two elements. PMID:27150429

  13. The ability of S.aureus to form biofilm on the Ti-6Al-7Nb scaffolds produced by Selective Laser Melting and subjected to the different types of surface modifications.

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    Szymczyk, Patrycja; Junka, Adam; Ziółkowski, Grzegorz; Smutnicka, Danuta; Bartoszewicz, Marzenna; Chlebus, Edward

    2013-01-01

    The Gram-positive coccus, Staphylococcus aureus, is the leading etiologic agent of limb and life-threatening biofilm-related infections in the patients following the orthopaedic implantations. The aim of the present paper is to estimate the ability of S. aureus to form biofilm on titanium alloy (Ti-6Al-7Nb) scaffolds produced by Selective Laser Melting (SLM) and subjected to the different types of surface modifications, including ultrasonic cleaning and chemical polishing. The results obtained indicate significantly the decreased ability of S.aureus to form biofilm on the surface of scaffolds subjected to the chemical polishing in comparison to the scaffolds cleaned ultrasonically. The data provided can be useful for future applications of the SLM technology in production of Ti-6Al-7Nb medical implants. PMID:23957680

  14. Studies on Correlation between E.coli Virulence Factor agn43 and Biofilm-forming Ability%大肠杆菌毒力因子agn43与生物被膜表型相关性研究

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    陈朝喜; 杨金福; 陈伟明

    2012-01-01

    To elucidate the correlation between biofilm-forming ability and virulence factors, improved crystal violet semi-quantitative method and common PCR were used for biofilm-forming ability quantitative analysis and phase variation antigen 43 detection in 180 pet-brone E. coli respectively; the results revealed that 30. 1% (55/180) of the strains detected agn43 and 96. 4%(53/55)of the agn43 positive strains performed biofilm-forming ability, showing significant difference from non-biofilm forming group(P<0. 01).%分别采用改良结晶紫半定量方法和常规PCR方法对180株宠物源性大肠杆菌进行生物被膜形成能力定量研究和相变抗原agn43检测,以分析大肠杆菌毒力因子agn43与生物被膜表型相关性.试验结果表明,30.1%(55/180)的菌株能够检测到agn43基因,96.4%(53/55)agn43阳性菌株具有不同程度的成膜能力,与无成膜能力组差异极显著(P<0.01).

  15. Biofilms: an emergent form of bacterial life.

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    Flemming, Hans-Curt; Wingender, Jost; Szewzyk, Ulrich; Steinberg, Peter; Rice, Scott A; Kjelleberg, Staffan

    2016-08-11

    Bacterial biofilms are formed by communities that are embedded in a self-produced matrix of extracellular polymeric substances (EPS). Importantly, bacteria in biofilms exhibit a set of 'emergent properties' that differ substantially from free-living bacterial cells. In this Review, we consider the fundamental role of the biofilm matrix in establishing the emergent properties of biofilms, describing how the characteristic features of biofilms - such as social cooperation, resource capture and enhanced survival of exposure to antimicrobials - all rely on the structural and functional properties of the matrix. Finally, we highlight the value of an ecological perspective in the study of the emergent properties of biofilms, which enables an appreciation of the ecological success of biofilms as habitat formers and, more generally, as a bacterial lifestyle. PMID:27510863

  16. Antimicrobial activities against biofilm formed by Proteus mirabilis isolates from wound and urinary tract infections

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    R Wasfi

    2012-01-01

    Full Text Available Background: Bacterial species are capable of living as biofilm and/or planktonic forms. There is increasing evidence for the role of bacterial biofilm in various wound and urinary tract infections (UTIs. The aim of the present study was to evaluate the ability of the bacteria, isolated from urinary tract infections (UTIs and wound infections, to form biofilm and correlate the role of biofilm with their antimicrobial resistance. Materials and Methods: All the isolated bacteria were screened for their ability to form biofilm using the microtitre plate method. Results: Wound isolates of Staphylococcus aureus and Enterobacter sp. had more biofilm forming capacity than the UTI isolates. Proteus mirabilis isolates were among the strongest biofilm forming bacteria and were chosen for antimicrobial study. In sub-MIC concentrations of antimicrobial agents used, ciprofloxacin was found to be the most effective in decreasing biofilm formation. On the other hand, ceftriaxone and ciprofloxacin were effective in partial removal of preformed biofilm biomass. Conclusion: Ciprofloxacin was more effective in killing bacterial cells especially at high antimicrobial concentrations that could be reached in urine levels and can be used in impregenating catheters.

  17. Interaction between biofilms formed by Pseudomonas aeruginosa and clarithromycin.

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    Yasuda, H; Ajiki, Y; Koga, T.; Kawada, H; Yokota, T.

    1993-01-01

    Interactions between bacterial biofilms formed by Pseudomonas aeruginosa and clarithromycin, a macrolide having no anti-P. aeruginosa activity, were investigated. P. aeruginosa incubated for 10 days on membrane filters formed biofilms on the surfaces of the filters. The biofilms were characterized by dense colonizations of bacteria and thick membranous structures that covered the colonies. Treatment of the biofilms with a relatively low concentration of clarithromycin for 5 days resulted in a...

  18. In vitro biofilm forming potential of Streptococcus suis isolated from human and swine in China

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    Guo Dawei

    2012-09-01

    Full Text Available Streptococcus suis is a swine pathogen and also a zoonotic agent. The formation of biofilms allows S. suis to become persistent colonizers and resist clearance by the host immune system and antibiotics. In this study, biofilm forming potentials of various S. suis strains were characterized by confocal laser scanning microscopy (CLSM, scanning electron microscopy (SEM and tissue culture plates stained with crystal violet. In addition, the effects of five antimicrobial agents on biofilm formation were assayed in this study. S. suis produced biofilms on smooth and rough surface. The nutritional contents including glucose and NaCl in the growth medium modulated biofilm formation. There was a significant difference in their biofilm-forming ability among all 46 S. suis strains. The biofilm-forming potential of S. suis serotype 9 was stronger than type 2 and all other types. However, biofilm formation was inhibited by five commonly used antimicrobial agents, penicillin, erythromycin, azithromycin, ciprofloxacin, and ofloxacin at subinhibitory concentrations, among which inhibition of ciprofloxacin and ofloxacin was stronger than that of other three antimicrobial agents.Our study provides a detailed analysis of biofilm formation potential in S. suis, which is a step towards understanding its role in pathogenesis, and eventually lead to a better understanding of how to eradicate S. suis growing as biofilms with antibiotic therapy.

  19. Investigation of biofilm formation in vitro ability of Listeria monocytogenes strains isolated from animals

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    Milanov Dubravka

    2007-01-01

    Full Text Available Listeria monocytogenes is the causative agent of listeriosis in humans and animals and an important food-born pathogen. Control of its presence in food processing plants, particularly on sites where food contamination is expected, is of paramount importance with respect to food safety and protection of human health. Numerous studies demonstrated that this organism can be isolated during several months, even several years, from diverse sites in food processing plants, which is due to its ability to adsorb onto inert surfaces and form a biofilm, alone or in coexistence with other bacterial species. In this study we investigated the ability of 16 animal isolates of L. monocytogenes to form a biofilm on polystyrene microtiter plates. The investigation was performed at three different temperatures 4oC, 25 oC and 37oC that are commonly suitable for growth of Listeria monocytogenes. The research was carried out using three different nutritive media: trypthon-soy broth with yeast extract (TSB-YE, brainheart infusion (BHI and 1/20 diluted trypthon-soy broth with yeast extract (1/20 TSB-YE. In order to investigate the biofilm formation in vitro an inoculum was prepared from 24-hours-old cultures of isolated strains of L.monocytogenes. The density of the inoculum was 2-10x107 cfu/mL (OD600=0.093 ± 0.009 in TSB-YE. The microtiter plates were incubated at cited temperatures during 48h. Colonization rate of L.monocytogenes strains on polystyrene surface and biofilm formation were monitored using crystal violet stain added to the microtiter plates, as well as using light microscopy. The tested strains demonstrated a diverse ability of biofilm formation, depending on the incubation temperature and nutritive medium. In this paper we presented the results obtained for four strains of Listeria monocytogenes isolated from brain samples of sheep, designated as 785/05, 593/05, 748/05, 1915/04 and one strain isolated from aborted calve's fetus, designated as 021

  20. Anti-biofilm properties of the antimicrobial peptide temporin 1Tb and its ability, in combination with EDTA, to eradicate Staphylococcus epidermidis biofilms on silicone catheters.

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    Maisetta, Giuseppantonio; Grassi, Lucia; Di Luca, Mariagrazia; Bombardelli, Silvia; Medici, Chiara; Brancatisano, Franca Lisa; Esin, Semih; Batoni, Giovanna

    2016-08-01

    In search of new antimicrobials with anti-biofilm potential, in the present study activity of the frog-skin derived antimicrobial peptide temporin 1Tb (TB) against Staphylococcus epidermidis biofilms was investigated. A striking ability of TB to kill both forming and mature S. epidermidis biofilms was observed, especially when the peptide was combined with cysteine or EDTA, respectively. Kinetics studies demonstrated that the combination TB/EDTA was active against mature biofilms already after 2-4-h exposure. A double 4-h exposure of biofilms to TB/EDTA further increased the therapeutic potential of the same combination. Of note, TB/EDTA was able to eradicate S. epidermidis biofilms formed in vitro on silicone catheters. At eradicating concentrations, TB/EDTA did not cause hemolysis of human erythrocytes. The results shed light on the anti-biofilm properties of TB and suggest a possible application of the peptide in the lock therapy of catheters infected with S. epidermidis. PMID:27351824

  1. Ultrastructure of Biofilms Formed by Bacteria from Industrial Processes

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    Raulio, Mari

    2010-01-01

    Microorganisms exist predominantly as sessile multispecies communities in natural habitats. Most bacterial species can form these matrix-enclosed microbial communities called biofilms. Biofilms occur in a wide range of environments, on every surface with sufficient moisture and nutrients, also on surfaces in industrial settings and engineered water systems. This unwanted biofilm formation on equipment surfaces is called biofouling. Biofouling can significantly decrease equipment performance a...

  2. In vitro biofilm forming capacity on abiotic contact surfaces by outbreak-associated Vibrio harveyi strains

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    Pallaval Veera Bramha Chari; Kuchipudi Viswadeepika; Bottu Anand Kumar

    2014-01-01

    Objective:To evaluate the in vitro biofilm forming capacity on abiotic food contact surfaces by Vibrio harveyi (V. harveyi) strains. Methods:Thirty six Gram-negative V. harveyi strains were isolated from various street vended seafood outlets in a food processing line and evaluated for their ability to produce mucoid biofilms on food contact surfaces using a microplate assay. Phenotypic characterization of mucoid biofilm producing V. harveyi strains were screened on Congo red agar, thiosulfate-citrate-bile salts-sucrose agar and tryptic soy agar, respectively. Results: Only five V. harveyi strains (14%) were mucoid biofilm producers characterized by formation of black colonies, whereas the remaining 31 strains (86%) were not capable of producing biofilm characterized by formation of red colonies or pinkish-red colonies with darkening at the centre. The morphological, physiological and biochemical characteristics of these isolates were studied using standard protocols. Strain identification was confirmed by polymerase chain reaction targeted to species-specific polymerase chain reaction primers VH-1 and VH-2 corresponding to variable regions of V. harveyi 16S rRNA sequence. All the biofilm-forming strains showed resistance to at least three antimicrobial compounds tested. V. harveyi strains isolated from various seafood were able to form biofilms of different capacity, and the strains VB267, VB238 and VB166 isolated from cat fish, shrimp and eel fish exhibited significantly greater biofilm forming ability compared to other isolates. Conclusions: It can be concluded from the present study that the strain VB166 was able to better attach and form subsequent biofilms on glass and stainless steel compared to high density polyethylene. These properties allow these bacteria to survive, proliferate and persist in street vended seafood outlets.

  3. In vitro biofilm forming capacity on abiotic contact surfaces by outbreak-associated Vibrio harveyi strains

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    Pallaval Veera Bramha Chari

    2014-02-01

    Full Text Available Objective: To evaluate the in vitro biofilm forming capacity on abiotic food contact surfaces by Vibrio harveyi (V. harveyi strains. Methods: Thirty six Gram-negative V. harveyi strains were isolated from various street vended seafood outlets in a food processing line and evaluated for their ability to produce mucoid biofilms on food contact surfaces using a microplate assay. Phenotypic characterization of mucoid biofilm producing V. harveyi strains were screened on Congo red agar, thiosulfate-citrate-bile salts-sucrose agar and tryptic soy agar, respectively. Results: Only five V. harveyi strains (14% were mucoid biofilm producers characterized by formation of black colonies, whereas the remaining 31 strains (86% were not capable of producing biofilm characterized by formation of red colonies or pinkish-red colonies with darkening at the centre. The morphological, physiological and biochemical characteristics of these isolates were studied using standard protocols. Strain identification was confirmed by polymerase chain reaction targeted to species-specific polymerase chain reaction primers VH-1 and VH-2 corresponding to variable regions of V. harveyi 16S rRNA sequence. All the biofilm-forming strains showed resistance to at least three antimicrobial compounds tested. V. harveyi strains isolated from various seafood were able to form biofilms of different capacity, and the strains VB267, VB238 and VB166 isolated from cat fish, shrimp and eel fish exhibited significantly greater biofilm forming ability compared to other isolates. Conclusions: It can be concluded from the present study that the strain VB166 was able to better attach and form subsequent biofilms on glass and stainless steel compared to high density polyethylene. These properties allow these bacteria to survive, proliferate and persist in street vended seafood outlets.

  4. Salmonella enterica isolates from layer farm environments are able to form biofilm on eggshell surfaces.

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    Pande, Vivek V; McWhorter, Andrea R; Chousalkar, Kapil K

    2016-08-01

    This study examined the eggshell biofilm forming ability of Salmonella enterica isolates recovered from egg farms. Multicellular behaviour and biofilm production were examined at 22 and 37°C by Congo red morphology and the crystal violet staining assay. The results indicated that the biofilm forming behaviour of Salmonella isolates was dependent on temperature and associated with serovars. Significantly greater biofilm production was observed at 22°C compared with 37°C. The number of viable biofilm cells attached to eggshells after incubation for 48 h at 22°C was significantly influenced by serovar. Scanning electron microscopic examination revealed firm attachment of bacterial cells to the eggshell surface. The relative expression of csgD and adrA gene was significantly higher in eggshell biofilm cells of S. Mbandaka and S. Oranienburg. These findings demonstrate that Salmonella isolates are capable of forming biofilm on the eggshell surface and that this behaviour is influenced by temperature and serovar. PMID:27268931

  5. Pseudomonas aeruginosa forms Biofilms in Acute InfectionIndependent of Cell-to-Cell Signaling

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    Schaber, J. Andy; Triffo, W.J.; Suh, Sang J.; Oliver, Jeffrey W.; Hastert, Mary C.; Griswold, John A.; Auer, Manfred; Hamood, Abdul N.; Rumbaugh, Kendra P.

    2006-09-20

    Biofilms are bacterial communities residing within a polysaccharide matrix that are associated with persistence and antibiotic resistance in chronic infections. We show that the opportunistic pathogen Pseudomonas aeruginosa forms biofilms within 8 hours of infection in thermally-injured mice, demonstrating that biofilms contribute to bacterial colonization in acute infections. P. aeruginosa biofilms were visualized within burned tissue surrounding blood vessels and adipose cells. Although quorum sensing (QS), a bacterial signaling mechanism, coordinates differentiation of biofilms in vitro, wild type and QS-deficient P. aeruginosa formed similar biofilms in vivo. Our findings demonstrate that P. aeruginosa forms biofilms on specific host tissues independent of QS.

  6. Anti-Biofilm and Immunomodulatory Activities of Peptides That Inhibit Biofilms Formed by Pathogens Isolated from Cystic Fibrosis Patients

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    César de la Fuente-Núñez

    2014-10-01

    Full Text Available Cystic fibrosis (CF patients often acquire chronic respiratory tract infections due to Pseudomonas aeruginosa and Burkholderia cepacia complex (Bcc species. In the CF lung, these bacteria grow as multicellular aggregates termed biofilms. Biofilms demonstrate increased (adaptive resistance to conventional antibiotics, and there are currently no available biofilm-specific therapies. Using plastic adherent, hydroxyapatite and flow cell biofilm models coupled with confocal and scanning electron microscopy, it was demonstrated that an anti-biofilm peptide 1018 prevented biofilm formation, eradicated mature biofilms and killed biofilms formed by a wide range of P. aeruginosa and B. cenocepacia clinical isolates. New peptide derivatives were designed that, compared to their parent peptide 1018, showed similar or decreased anti-biofilm activity against P. aeruginosa biofilms, but increased activity against biofilms formed by the Gram-positive bacterium methicillin resistant Staphylococcus aureus. In addition, some of these new peptide derivatives retained the immunomodulatory activity of 1018 since they induced the production of the chemokine monocyte chemotactic protein-1 (MCP-1 and suppressed lipopolysaccharide-mediated tumor necrosis factor-α (TNF-α production by human peripheral blood mononuclear cells (PBMC and were non-toxic towards these cells. Peptide 1018 and its derivatives provide promising leads for the treatment of chronic biofilm infections and hyperinflammatory lung disease in CF patients.

  7. Helicobacter pylori-coccoid forms and biofilm formation

    DEFF Research Database (Denmark)

    Andersen, Leif Percival; Rasmussen, Lone

    2009-01-01

    Electron microscopic studies have shown that Helicobacter pylori occurs in three stages: spiral forms, coccoid forms and degenerative forms. The spiral forms are viable, culturable, virulent and can colonize experimental animals and induce inflammation. The coccoid forms may also be viable but are....... Helicobacter pylori does not seem to take part in biofilm formation in the oral cavity even though the bacterium may be detected....... nonculturable, less virulent and are less likely to colonize and induce inflammation in experimental animals than the spiral forms. The degenerative forms are pyknotic, nonculturable, coccoid forms of dead H. pylori. These forms cannot be cultured and the cell membrane has disintegrated but gene material can be...

  8. Escherichia coli O157:H7 strains isolated from “High Event Period” beef contamination have strong biofilm forming ability and low sanitizer susceptibility which are associated with high pO157 plasmid copy number

    Science.gov (United States)

    In the meat industry, a “High Event Period” (HEP) is defined as a time period when beef processing establishments experience an increased occurrence of product contamination by E. coli O157:H7. Our previous studies suggested that bacterial biofilm formation and sanitizer resistance might contribute...

  9. Coryneform bacteria in human semen: inter-assay variability in species composition detection and biofilm production ability

    Directory of Open Access Journals (Sweden)

    Silver Türk

    2014-02-01

    Full Text Available Background: Coryneform bacteria constitute an important segment of male urogenital microbiota. They have been generally considered as saprophytes, although some species have been associated with prostatitis as well. At the same time, biofilm infections have been suspected as a cause of prostatitis. Objective: To identify a set of coryneform bacteria isolated from semen of either healthy men or prostatitis patients applying different methods to reveal inter-assay variability and to determine their ability of adhesion and biofilm production. Design: Coryneform bacteria were identified by API Coryne 2.0 biochemical identification system and 16S rDNA sequencing using different primer sets. Quantitative assessment of biofilm production was performed using crystal violet binding assay method. Results: The most common species were Corynebacterium seminale, C. minutissimum, and Dermabacter hominis. Altogether 14 species and related genera were found. We observed the best inter-assay agreement when identifying C. seminale. Biofilm was observed in 7 out of 24 strains. The biofilm-producing strains belonged to Arthrobacter cumminsii, Dermabacter hominis, C. minutissimum, and Actinomyces neuii. No differences were found between the strains originating from prostatitis patients and healthy men. Dermabacter hominis strains were more potent biofilm producers than C. seminale strains (p=0.048. Conclusions: We can conclude that a wide variety of coryneform bacteria can be found from the male genital tract, although their exact identification is problematic due to insufficient representation in databases. Nearly one third of the strains are able to form biofilm that may give them an advantage for surviving several host- and treatment-related conditions.

  10. Triplex-forming ability of modified oligonucleotides

    DEFF Research Database (Denmark)

    Højland, Torben; Babu, Bolle Ravindra; Bryld, Torsten;

    2007-01-01

    We present our studies on the ability of several different nucleotide analogs as triplex-forming oligonucleotides. The modifications tested include 4'-C-hydroxymethyl, LNA, 2'-amino-LNA and N2'-functionalized 2'-amino-LNA. Triplexes containing monomers of N2'-glycyl-functionalized 2'-amino-LNA are...

  11. Glass forming ability of calcium aluminosilicate melts

    DEFF Research Database (Denmark)

    Moesgaard, Mette; Yue, Yuanzheng

    2011-01-01

    The glass forming ability (GFA) of two series of calcium aluminosilicate melts is studied by measuring their viscous behavior and crystallization tendency. The first series consists of five compositions on the joining line between the eutectic point of anorthite-wollastonite-tridymite and that of...

  12. Control of the Biofilms Formed by Curli- and Cellulose-Expressing Shiga Toxin-Producing Escherichia coli Using Treatments with Organic Acids and Commercial Sanitizers.

    Science.gov (United States)

    Park, Yoen Ju; Chen, Jinru

    2015-05-01

    Biofilms are a mixture of bacteria and extracellular products secreted by bacterial cells and are of great concern to the food industry because they offer physical, mechanical, and biological protection to bacterial cells. This study was conducted to quantify biofilms formed by different Shiga toxin-producing Escherichia coli (STEC) strains on polystyrene and stainless steel surfaces and to determine the effectiveness of sanitizing treatments in control of these biofilms. STEC producing various amounts of cellulose (n = 6) or curli (n = 6) were allowed to develop biofilms on polystyrene and stainless steel surfaces at 28°C for 7 days. The biofilms were treated with 2% acetic or lactic acid and manufacturer-recommended concentrations of acidic or alkaline sanitizers, and residual biofilms were quantified. Treatments with the acidic and alkaline sanitizers were more effective than those with the organic acids for removing the biofilms. Compared with their counterparts, cells expressing a greater amount of cellulose or curli formed more biofilm mass and had greater residual mass after sanitizing treatments on polystyrene than on stainless steel. Research suggests that the organic acids and sanitizers used in the present study differed in their ability to control biofilms. Bacterial surface components and cell contact surfaces can influence both biofilm formation and the efficacy of sanitizing treatments. These results provide additional information on control of biofilms formed by STEC. PMID:25951395

  13. Biofilm-Forming Methicillin-Resistant Staphylococcus aureus Survive in Kupffer Cells and Exhibit High Virulence in Mice

    Directory of Open Access Journals (Sweden)

    Takuto Oyama

    2016-06-01

    Full Text Available Although Staphylococcus aureus is part of the normal body flora, heavy usage of antibiotics has resulted in the emergence of methicillin-resistant strains (MRSA. MRSA can form biofilms and cause indwelling foreign body infections, bacteremia, soft tissue infections, endocarditis, and osteomyelitis. Using an in vitro assay, we screened 173 clinical blood isolates of MRSA and selected 20 high-biofilm formers (H-BF and low-biofilm formers (L-BF. These were intravenously administered to mice and the general condition of mice, the distribution of bacteria, and biofilm in the liver, lung, spleen, and kidney were investigated. MRSA count was the highest in the liver, especially within Kupffer cells, which were positive for acid polysaccharides that are associated with intracellular biofilm. After 24 h, the general condition of the mice worsened significantly in the H-BF group. In the liver, bacterial deposition and aggregation and the biofilm-forming spot number were all significantly greater for H-BF group than for L-BF. CFU analysis revealed that bacteria in the H-BF group survived for long periods in the liver. These results indicate that the biofilm-forming ability of MRSA is a crucial factor for intracellular persistence, which could lead to chronic infections.

  14. Isolation of biofilm-forming bacteria from a fresh-cut processing plant and co-culturing with E. coli O157:H7

    Science.gov (United States)

    In produce processing plants, biofilms can theoretically provide a supporting environment for pathogenic bacteria that is resistant to cleaning and sanitizing efforts. The objective of this study was to recover bacteria from a commercial produce processing plant that have the ability to form biofilm...

  15. XML The Ability of Cellulose Polysaccharide and Curli Pili Production in Uropathogenic Escherichia Coli and its Association with Biofilm Formation Intensity

    Directory of Open Access Journals (Sweden)

    Zahra Khozein (MSc

    2016-01-01

    Full Text Available Background and Objective: the Formation of urinary infection by uropathogenic E.coli needs numerous virulence factors and biofilm formation is among these factors. Bacteria that form biofilms express phenotype traits that appear according to the bacteria type. Cellulose is an important compound on the outside of E.coli causing bacterial cell-cell reactions and connection to nonliving surfaces. Curli pili cause the reaction between cell-cell and surface-cell in biofilms and lead to bacteria aggregation. Microorganisms’ ability to form biofilm on a surface depends on the surface nature and its conditions. This study aimed at determining the production ability of cellulose polysaccharide and curli pili in UPEC strains, and its correlation with formation and intensity of biofilm. Methods: In this study carried out to compare the ability of cellulose and pili curli production ability in 40 uropathogenic E.coli isolates ,by morphotype method in Congo Red medium (CR, each isolate was incubated at 37 oC, for 24 hours. After 24 hours, all colonies’ morphology characteristics were studied Results: It was shown that 67.5% of strains produced cellulose and 72.5% produced curli pili. In addition, 92.6% and 89% of isolates that produce cellulose and curli, respectively, had a moderate to strong biofilm. Moreover, it was shown that there is a significant correlation between cellulose and / or curli pili production with biofilm intensity. Conclusion: About 70% of E.coli isolates from patients' urine are able to produce cellulose or curli pili; therefore, it can be concluded that the production of these two combinations is effective in amount and intensity of biofilm formation.

  16. Characterizing pilus-mediated adhesion of biofilm-forming E. coli to chemically diverse surfaces using atomic force microscopy.

    Science.gov (United States)

    Xu, He; Murdaugh, Anne E; Chen, Wei; Aidala, Katherine E; Ferguson, Megan A; Spain, Eileen M; Núñez, Megan E

    2013-03-01

    Biofilms are complex communities of microorganisms living together at an interface. Because biofilms are often associated with contamination and infection, it is critical to understand how bacterial cells adhere to surfaces in the early stages of biofilm formation. Even harmless commensal Escherichia coli naturally forms biofilms in the human digestive tract by adhering to epithelial cells, a trait that presents major concerns in the case of pathogenic E. coli strains. The laboratory strain E. coli ZK1056 provides an intriguing model system for pathogenic E. coli strains because it forms biofilms robustly on a wide range of surfaces.E. coli ZK1056 cells spontaneously form living biofilms on polylysine-coated AFM cantilevers, allowing us to measure quantitatively by AFM the adhesion between native biofilm cells and substrates of our choice. We use these biofilm-covered cantilevers to probe E. coli ZK1056 adhesion to five substrates with distinct and well-characterized surface chemistries, including fluorinated, amine-terminated, and PEG-like monolayers, as well as unmodified silicon wafer and mica. Notably, after only 0-10 s of contact time, the biofilms adhere strongly to fluorinated and amine-terminated monolayers as well as to mica and weakly to "antifouling" PEG monolayers, despite the wide variation in hydrophobicity and charge of these substrates. In each case the AFM retraction curves display distinct adhesion profiles in terms of both force and distance, highlighting the cells' ability to adapt their adhesive properties to disparate surfaces. Specific inhibition of the pilus protein FimH by a nonhydrolyzable mannose analogue leads to diminished adhesion in all cases, demonstrating the critical role of type I pili in adhesion by this strain to surfaces bearing widely different functional groups. The strong and adaptable binding of FimH to diverse surfaces has unexpected implications for the design of antifouling surfaces and antiadhesion therapies. PMID

  17. Characterisation of biofilms formed by Lactobacillus plantarum WCFS1 and food spoilage isolates

    NARCIS (Netherlands)

    Fernández Ramírez, M.D.; Smid, E.J.; Abee, T.; Nierop Groot, M.N.

    2015-01-01

    Lactobacillus plantarum has been associated with food spoilage in a wide range of products and the biofilm growth mode has been implicated as a possible source of contamination. In this study we analysed the biofilm forming capacity of L. plantarum WCFS1 and six food spoilage isolates. Biofilm forma

  18. Pseudomonas aeruginosa Forms Biofilms in Acute Infection Independent of Cell-to-Cell Signaling▿ †

    OpenAIRE

    Schaber, J. Andy; Triffo, W.J.; Suh, Sang J.; Oliver, Jeffrey W.; Hastert, Mary C.; Griswold, John A.; Auer, Manfred; Hamood, Abdul N; Rumbaugh, Kendra P.

    2007-01-01

    Biofilms are bacterial communities residing within a polysaccharide matrix that are associated with persistence and antibiotic resistance in chronic infections. We show that the opportunistic pathogen Pseudomonas aeruginosa forms biofilms within 8 h of infection in thermally injured mice, demonstrating that biofilms contribute to bacterial colonization in acute infections as well. Using light, electron, and confocal scanning laser microscopy, P. aeruginosa biofilms were visualized within burn...

  19. Identification and Localization of Extraradicular Biofilm-Forming Bacteria Associated with Refractory Endodontic Pathogens

    OpenAIRE

    Noguchi, Nobuo; Noiri, Yuichiro; Narimatsu, Masahiro; Ebisu, Shigeyuki

    2005-01-01

    Bacterial biofilms have been found to develop on root surfaces outside the apical foramen and be associated with refractory periapical periodontitis. However, it is unknown which bacterial species form extraradicular biofilms. The present study aimed to investigate the identity and localization of bacteria in human extraradicular biofilms. Twenty extraradicular biofilms, used to identify bacteria using a PCR-based 16S rRNA gene assay, and seven root-tips, used to observe immunohistochemical l...

  20. Heated scallop-shell powder treatment for deactivation and removal of Listeria sp. biofilm formed at a low temperature.

    Science.gov (United States)

    Shimamura, Nobumitsu; Irie, Fumio; Yamakawa, Takahiro; Kikuchi, Mikio; Sawai, Jun

    2015-01-01

    The ability of heated scallop-shell powder (HSSP) to work against Listeria sp. biofilm formed at a low temperature was investigated. A biofilm of L. innocua ATCC 33090 was grown on a glass plate at 15˚C for 15 days, then immersed in HSSP slurry. Following treatment, the disinfection ability of the HSSP against the biofilm was non-destructively quantified by conductimetric assay. The biofilm grown at 15˚C was less sensitive than that grown at 37˚C to HSSP treatment and alkaline treatment. The biofilm grown at 15˚C was completely deactivated by 30 min of HSSP treatment (10 mg/mL, pH 12.5). In contrast, after 30 min treatment with alkaline solution at pH 12.5 or sodium hypochlorite (100 ppm), the activity was reduced by only one order of magnitude. The disinfection efficacy of HSSP (10 mg/mL) against L. innocua is similar to or higher than that of sodium hypochlorite (200 ppm). Fluorescence microscopy validated the results of the conductimetric assay. Therefore, HSSP treatment is a potentially powerful alternative control agent against Listeria sp. biofilms that present hazards in the food industry. PMID:26133513

  1. Adaptive response of single and binary biofilms formed in the presence of benzalkonium chloride

    OpenAIRE

    Pereira, Maria Olívia; Machado, Idalina; Lopes, Susana Patrícia; H. Costa

    2009-01-01

    In actual situations bacteria can live nicely in hostile environments in part due to its ability to live in biofilms and to regulate gene expression as an adaptive response to a variety of stresses. This altered profile, compared to planktonic counterparts, as well as the interactions amongst the several strains existing within the biofilm seems to be responsible for the gradual loss of susceptibility to antimicrobials. The presence of biofilms on the surfaces of various types of medical surf...

  2. Characterization of starvation-induced dispersion in Pseudomonas putida biofilms

    DEFF Research Database (Denmark)

    Gjermansen, Morten; Ragas, Paula Cornelia; Sternberg, Claus;

    2005-01-01

    that they must be able to regulate their ability to form biofilm and to dissolve biofilm. We present an investigation of a biofilm dissolution process occurring in flow-chamber-grown Pseudomonas putida biofilms. Local starvation-induced biofilm dissolution appears to be an integrated part of P. putida...

  3. Characterization of Mucosal Candida albicans Biofilms

    OpenAIRE

    Dongari-Bagtzoglou, Anna; Kashleva, Helena; Dwivedi, Prabhat; Diaz, Patricia; Vasilakos, John

    2009-01-01

    C. albicans triggers recurrent infections of the alimentary tract mucosa that result from biofilm growth. Although the ability of C. albicans to form a biofilm on abiotic surfaces has been well documented in recent years, no information exists on biofilms that form directly on mucosal surfaces. The objectives of this study were to characterize the structure and composition of Candida biofilms forming on the oral mucosa. We found that oral Candida biofilms consist of yeast, hyphae, and commens...

  4. Photodynamic therapy for the eradication of biofilms formed by catheter associated Pseudomonas aeruginosa strains

    Directory of Open Access Journals (Sweden)

    Viviana Teresa Orlandi

    2011-06-01

    Full Text Available Pseudomonas aeruginosa has emerged as a major opportunistic pathogen causing catheter-associated urinary tract infections (CA-UTIs associated with high mortality and morbidity. In this study 18 P. aeruginosa isolates from urine of catheterized patients were evaluated for in vitro biofilm formation.All the tested strains showed the ability to form biofilm more thicker than those formed by a cohort of 29 blood culture strains belonging to the same species. Photodynamic antimicrobial chemotherapy (PACT is a novel antimicrobial treatment that exploits a photosensitizer (PS and visible light to induce lethal oxidative damages in bacterial cells and could be used as local antimicrobial approach in CA-UTIs. Here we tested the susceptibility of planktonic and sessile cultures of P. aeruginosa strains, the model strain PAO1 and CA-UTI isolates, to photodynamic inactivation with a di cationic porphyrinic photosensitizer, the 5, 15-di (N-benzyl-4-pyridynium-porphyrin di chloride.Although Pseudomonas aeruginosa is regarded as a difficult target for antimicrobial chemotherapy, satisfactory bactericidal activities on both planktonic and biofilm cultures were observed.

  5. Isolation and identification of bacteria able to form biofilms from deep subsurface environments

    International Nuclear Information System (INIS)

    Migration radionuclides in an underground environment are one of the major concerns in the safety assessment of a geological repository. Biofilms can have an impact on the transport of radionuclides in several ways: (1) by acting as a barrier to radionuclide sorption onto geological surfaces, or (2) by providing a sorption site for radionuclides, or (3) by trapping many things, including radionuclides. Little is known about bacterial effects on the biofilm formation deep underground. In this study, we isolated bacterial strains from deep groundwater and evaluated the biofilm formation abilities of these strains by crystal violet assay. Bacterial strains were isolated from ground-water collected at -140 m in the 07-V140-M01 borehole at the Horonobe Underground Research Center, Japan. The crystal violet assay showed that 98% of the isolated strains had biofilm formation abilities under tested conditions. This result suggested that biofilm formation must not be neglected in the study of migration radionuclides in nuclear waste repositories. The isolated strains produced differential amounts of biofilm, although they were identified as the same Pseudomonas species, suggesting that biofilm formation abilities varied at different strain levels. These results support the conclusion that the assessment of biofilm impact on the transport of radionuclides in a geological repository must consider the variation in biofilm formation as a function of strain level. (author)

  6. A bioaugmentation failure caused by phage infection and weak biofilm formation ability

    Institute of Scientific and Technical Information of China (English)

    FU Songzhe; FAN Hongxia; LIU Shuangjiang; LIU Ying; LIU Zhipei

    2009-01-01

    Two biological aerated filters (BAF) were setup for ammonia removal treatment of the circulation water in a marine aquaculture.One of the BAFs was bioaugmented with a heterotrophic nitrifying bacterium, Lutimonas sp.H10, but the ammonia removal was not improved; the massive inoculation was even followed by a nitrification breakdown from day 9 to 18, while nitrification remained stable in the control BAF operated under the same conditions.Fluorescent in situ hybridization (FISH) with rRNA-targeted probes and cultivable method revealed that Lutimonas sp.H10 almost disappeared from the bioaugomented BAF within 3 d, and this was mainly due to the infection of a specific phage as revealed by flask experiment, plaque assay and transmission electron observation.Analyses of 16S rRNA gene libraries showed that bacterial groups from two reactors evolved differently and an overgrowth of protozoa was observed in the bioaugmented BAF.Therefore, phage infection and poor biofilm forming ability of the inoculated strain are the main reasons for bioaugmentation failure.In addition, grazing by protozoa of the bacteria might be the reason for the nitrification breakdown in bioaugmented BAF during day 9-18.

  7. Characterization of Newly-Formed Manganese (Hydr)oxides in Biofilms in Pinal Creek, Arizona

    Science.gov (United States)

    Gilbert, H.; Conklin, M.; O'Day, P.

    2003-12-01

    Active, biologically mediated precipitation of manganese (hydr)oxides (Mn-oxides) in Pinal Creek, Arizona, a stream with a history of high manganese levels due to historic mining practices, was studied to determine the identity of newly formed phases and their ability to sequester other metals. Packages of crushed grains of eight clean mineral substrates, quartz, ilmenite, microcline, rutile, magnetite, hematite and labradorite, were placed in Pinal Creek for one to three months. Glass slides were set out as well in order to characterize biofilm formation. After retrieval and drying, the coating distributions were characterized using scanning electron microscopy (SEM), energy dispersive analysis, and X-ray absorption spectroscopy. Morphologically, coating material developed on the different substrates after one month appeared similar to those developed after two and three months. Overall, the SEM images indicate poorly crystalline, aggregated particles that are small (less than a few microns in general) and lack geometric regularity, although size estimates are somewhat hindered by particle aggregation. The coatings that formed on the microscope slides are characterized as biofilms, as numerous microorganisms were observed using microscopy, both confocal and SEM. Samples were further characterized using extended x-ray absorption fine structure spectroscopy (EXAFS) on coatings that had been separated from mineral substrates. EXAFS spectra of material from rutile and quartz substrates and the biofilm were analyzed and fit, using a natural and synthetic birnessite compounds as reference spectra. This analysis suggests that the rutile, quartz, and biofilm samples are composed of a disordered Mn-oxide that is similar in local structure to a natural birnessite of low symmetry. The formation of disordered, poorly crystalline birnessite is important, as it is an extremely efficient metal scavenger and the interlayer vacancies in the birnessite structure aids in metal

  8. Unsaturated fatty acid, cis-2-decenoic acid, in combination with disinfectants or antibiotics removes pre-established biofilms formed by food-related bacteria.

    Directory of Open Access Journals (Sweden)

    Shayesteh Sepehr

    Full Text Available Biofilm formation by food-related bacteria and food-related pathogenesis are significant problems in the food industry. Even though much disinfection and mechanical procedure exist for removal of biofilms, they may fail to eliminate pre-established biofilms. cis-2 decenoic acid (CDA, an unsaturated fatty acid messenger produced by Pseudomonas aeruginosa, is reportedly capable of inducing the dispersion of established biofilms by multiple types of microorganisms. However, whether CDA has potential to boost the actions of certain antimicrobials is unknown. Here, the activity of CDA as an inducer of pre-established biofilms dispersal, formed by four main food pathogens; Staphylococcus aureus, Bacillus cereus, Salmonella enterica and E. coli, was measured using both semi-batch and continuous cultures bioassays. To assess the ability of CDA combined biocides treatments to remove pre-established biofilms formed on stainless steel discs, CFU counts were performed for both treated and untreated cultures. Eradication of the biofilms by CDA combined antibiotics was evaluated using crystal violet staining. The effect of CDA combined treatments (antibiotics and disinfectants on biofilm surface area and bacteria viability was evaluated using fluorescence microscopy, digital image analysis and LIVE/DEAD staining. MICs were also determined to assess the probable inhibitory effects of CDA combined treatments on the growth of tested microorganisms' planktonic cells. Treatment of pre-established biofilms with only 310 nM CDA resulted in at least two-fold increase in the number of planktonic cells in all cultures. While antibiotics or disinfectants alone exerted a trivial effect on CFU counts and percentage of surface area covered by the biofilms, combinational treatments with both 310 nM CDA and antibiotics or disinfectants led to approximate 80% reduction in biofilm biomass. These data suggests that combined treatments with CDA would pave the way toward

  9. ENTEROCOCCI AND THEIR ABILITY TO FORM A BIOFILM

    OpenAIRE

    Jana Bezeková; Margita Čanigová; Miroslav Kročko; Jana Račková; Viera Ducková

    2012-01-01

    Number of enterococci determined in raw milk cistern samples was in range of 2.95 to 4.18 log CFU.ml-1 and raw milk samples obtained from storage tanks contained enterococci count in the range of 3.04 to 4.51 log CFU.ml-1. Results of microbiological quality evaluation showed, that count of enterococci increased during cold storage of raw milk. Portion of enterococci from the total microflora of raw milk taken from cistern samples was 0.44 %, otherwise in raw milk samples taken from storage ...

  10. Behaviour of biofilms formed by Pseudomonas fluorescens under different flow regimes when exposed to surfactants : role of the biofilm mechanical stability

    OpenAIRE

    Simões, M; Pereira, M. O.; Vieira, M. J.

    2005-01-01

    The effectiveness of cetyltrimethyl ammonium bromide (CTAB) and sodium dodecyl sulfate (SDS) to control biofilms formed by Pseudomonas fluorescens on stainless steel slides under laminar and turbulent conditions, using a flow cell reactor, is compared in this study. The antimicrobial action of the surfactants was evaluated in terms of the activity of the biofilm, the biofilm mass that remained on the surface after treatment and the biofilm morphological characteristics. The mec...

  11. In vivo cell aggregations of a recent swine biofilm-forming isolate of Leptospira interrogans strain from Argentina.

    Science.gov (United States)

    Brihuega, Bibiana; Samartino, Luis; Auteri, Carmelo; Venzano, Agustín; Caimi, Karina

    2012-01-01

    Leptospirosis is a zoonosis of ubiquitous distribution caused by spirochetes. Leptospires exist either as saprophytic water-associated organisms or as animal pathogens that can survive in water. Previous works have demonstrated that both saprophytic and pathogenic leptospires are able to produce functional biofilms, which consist of a community of bacteria embedded in an extracellular matrix attached to a surface. This structure is believed to provide protection from environmental aggressiveness. In the present study, we analyzed the capacity of biofilm formation both of a a recent field isolate of Leptospira interrogans serovar Pomona obtained from an aborted swine fetus and of the saprophytic Leptospira biflexa serovar Patoc. We used light microscopy, immunofluorescence, and scanning electron microscopic examinations on glass and polystyrene plate models to evaluate the process in vitro. The ability to form bacterial aggregations in vivo was tested using pregnant guinea pigs infected with both strains. We obtained biofilms both on glass and plastic surfaces. Scanning electron microscopic analysis showed differences in the biofilm structure formed by both strains. L. interrogans serovar Pomona cell aggregations were observed in placental tissues by light microscopy. Biofilms and cell aggregations are consistent with the life of saprophytic strains in water and could help pathogenic strains to colonize the host and lead to abortion in pregnant animals. PMID:23102459

  12. Sfp-type PPTase inactivation promotes bacterial biofilm formation and ability to enhance wheat drought tolerance.

    Science.gov (United States)

    Timmusk, Salme; Kim, Seong-Bin; Nevo, Eviatar; Abd El Daim, Islam; Ek, Bo; Bergquist, Jonas; Behers, Lawrence

    2015-01-01

    Paenibacillus polymyxa is a common soil bacterium with broad range of practical applications. An important group of secondary metabolites in P. polymyxa are non-ribosomal peptide and polyketide derived metabolites (NRPs/PKs). Modular non-ribosomal peptide synthetases catalyze main steps in the biosynthesis of the complex secondary metabolites. Here we report on the inactivation of an A26 Sfp-type 4'-phosphopantetheinyl transferase (Sfp-type PPTase). The inactivation of the gene resulted in loss of NRPs/PKs production. In contrast to the former Bacillus spp. model the mutant strain compared to wild type showed greatly enhanced biofilm formation ability. A26Δsfp biofilm promotion is directly mediated by NRPs/PKs, as exogenous addition of the wild type metabolite extracts restores its biofilm formation level. Wheat inoculation with bacteria that had lost their Sfp-type PPTase gene resulted in two times higher plant survival and about three times increased biomass under severe drought stress compared to wild type. Challenges with P. polymyxa genetic manipulation are discussed. PMID:26052312

  13. Influence of papain in biofilm formed by methicillin-resistant Staphylococcus epidermidis and methicillin-resistant Staphylococcus haemolyticus isolates

    OpenAIRE

    Hanna Lara da Cruz Dinéas de Oliveira; Maria Emília de Castro Kling Fleming; Patrícia Vollu Silva; Geraldo Renato de Paula; Débora Omena Futuro; Guillermo Coca Velarde; Luciana Maria Ramires Esper; Lenise Arneiro Teixeira

    2014-01-01

    Methicillin-resistant Staphylococcus epidermidis (MRSE) and methicillin-resistant Staphylococcus haemolyticus (MRSHa) are important coagulase-negative staphylococci. They are often isolated from bacteremia in humans mainly due to their ability to form biofilm on the surfaces of medical devices. Papain is a complex mixture of proteolytic enzymes and peroxidases extracted from the latex of Carica papaya and it is recognized by accelerating the healing process of wounds. This study aimed to eval...

  14. Effect of Amylase, Papaein and Pepsin enzyme solutions on Candida biofilm formed on acrylic resin plates

    OpenAIRE

    AA jafari_nodoushan; FalahTafti A; Emmami P; Ashouri

    2013-01-01

    Background and Aim: Denture stomatitis results from colonization of oral Candida on the surface of denture acrylic base. To control this infection,Candida biofilm formation must be prevented using mechanical and chemical decontamination. The purpose of the present study was to evaluate the effect of Amylase, Papaein and Pepsin solutions on removal of Candida Albicans plaques formed on acrylic resin plates. Materials and Methods: In this experimental study Candida biofilm was formed on 220 ...

  15. Pattern differentiation in co-culture biofilms formed by Staphylococcus aureus and Pseudomonas aeruginosa

    DEFF Research Database (Denmark)

    Yang, Liang; Liu, Yang; Markussen, Trine;

    2011-01-01

    -culture biofilms. By growing co-culture biofilms of S. aureus with P. aeruginosa mutants in a flow-chamber system and observing them using confocal laser scanning microscopy, we show that wild-type P. aeruginosa PAO1 facilitates S. aureus microcolony formation. In contrast, P. aeruginosa mucA and rpoN mutants do...... not facilitate S. aureus microcolony formation and tend to outcompete S. aureus in co-culture biofilms. Further investigations reveal that extracellular DNA (eDNA) plays an important role in S. aureus microcolony formation and that P. aeruginosa type IV pili are required for this process, probably through...... their ability to bind to eDNA. Furthermore, P. aeruginosa is able to protect S. aureus against Dictyostelium discoideum phagocytosis in co-culture biofilms....

  16. Functional analysis of stress protein data in a flor yeast subjected to a biofilm forming condition

    OpenAIRE

    Moreno-García, Jaime; Mauricio, Juan Carlos; Moreno, Juan; García-Martínez, Teresa

    2016-01-01

    In this data article, an OFFGEL fractionator coupled to LTQ Orbitrap XL MS equipment and a SGD filtering were used to detect in a biofilm-forming flor yeast strain, the maximum possible number of stress proteins under the first stage of a biofilm formation conditions (BFC) and under an initial stage of fermentation used as reference, so-called non-biofilm formation condition (NBFC). Protein functional analysis – based on cellular components and biological process GO terms – was performed for ...

  17. Characterizing Pilus-Mediated Adhesion of Biofilm-Forming E. coli to Chemically Diverse Surfaces Using Atomic Force Microscopy

    OpenAIRE

    Xu, He; Murdaugh, Anne E.; Chen, Wei; Aidala, Katherine E.; Ferguson, Megan A.; Spain, Eileen M.; Núñez, Megan E.

    2013-01-01

    Biofilms are complex communities of microorganisms living together at an interface. Because biofilms are often associated with contamination and infection, it is critical to understand how bacterial cells adhere to surfaces in the early stages of biofilm formation. Even harmless commensal Escherichia coli naturally forms biofilms in the human digestive tract by adhering to epithelial cells, a trait that presents major concerns in the case of pathogenic E. coli strains. The laboratory strain E...

  18. Effect of Amylase, Papaein and Pepsin enzyme solutions on Candida biofilm formed on acrylic resin plates

    OpenAIRE

    A Jafari Nodoushan; A Fallah Tafti; Emami, P; H Ashoori

    2013-01-01

    Abstract:     Background and Aim: Denture stomatitis results from colonization of oral Candida on the surface of denture acrylic base. To control this infection,Candida biofilm formation must be prevented using mechanical and chemical decontamination. The purpose of the present study was to evaluate the effect of Amylase, Papaein and Pepsin solutions on removal of Candida Albicans plaques formed on acrylic resin plates.   Materials and Methods : In this experimental study Candida biofilm was ...

  19. Characterization of biofilm-forming microorganisms isolated from vaginal exudate in Portugal

    OpenAIRE

    Alves, P.; Castro, J.; Cereija, Tatiana Barros Reis; Henriques, Ana Filipa Frutuoso Mendes; Cerca, Nuno

    2012-01-01

    Bacterial vaginosis (BV) is one of the most common gynaecological conditions affecting women in the reproductive age, and can lead to increase risk gynaecological infections and pre-term labour. The aetiology of this pathology is still poorly understood, but recent reports referring to the presence of anaerobic biofilms both in the healthy and BV vagina (with different microbial compositions) have led to the theory that the microorganisms that form biofilms may be relevant for the aetiology o...

  20. The biofilm formation ability of Listeria monocytogenes isolated from meat, poultry, fish and processing plant environments is related to serotype and pathogenic profile of the strains

    Directory of Open Access Journals (Sweden)

    Domenico Meloni

    2012-10-01

    Full Text Available In the present study, the relationships between serotype, pathogenic profile and in vitro biofilm formation of 106 Listeria monocytogenes strains, having no epidemiological correlation and isolated from different environmental and food sources, were analyzed. The quantitative assessment of the in vitro biofilm formation was carried out by using a microtiter plate assay with spectrophotometric reading (OD620. The isolates were also submitted to serogrouping using the target genes lmo0737, lmo1118, ORF2819, ORF2110, prs, and to the evaluation of the presence of the following virulence genes: prfA, hlyA, rrn, inlA, inlB, iap, plcA, plcB, actA and mpl, by multiplex PCRs. The 62% of the strains showed weak or moderate in vitro ability in biofilm formation, in particular serotypes 1/2b and 4b, frequently associated with sporadic or epidemic listeriosis cases. The 25% of these isolates showed polymorphism for the actA gene, producing a fragment of 268-bp instead of the expected 385-bp. The deletion of nucleotides in this gene seems to be related to enhanced virulence properties among these strains. Strains belonging to serotypes associated with human infections and characterized by pathogenic potential are capable to persist within the processing plants forming biofilm.

  1. The Role of Biofilms in the Sedimentology of Actively Forming Gypsum Deposits at Guerrero Negro, Mexico

    Science.gov (United States)

    Vogel, Marilyn B.; Des Marais, David J.; Turk, Kendra A.; Parenteau, Mary N.; Jahnke, Linda L.; Kubo, Michael D. Y.

    2009-11-01

    Actively forming gypsum deposits at the Guerrero Negro sabkha and saltern system provided habitats for stratified, pigmented microbial communities that exhibited significant morphological and phylogenetic diversity. These deposits ranged from meter-thick gypsum crusts forming in saltern seawater concentration ponds to columnar microbial mats with internally crystallized gypsum granules developing in natural anchialine pools. Gypsum-depositing environments were categorized as forming precipitation surfaces, biofilm-supported surfaces, and clastic surfaces. Each surface type was described in terms of depositional environment, microbial diversity, mineralogy, and sedimentary fabrics. Precipitation surfaces developed in high-salinity subaqueous environments where rates of precipitation outpaced the accumulation of clastic, organic, and/or biofilm layers. These surfaces hosted endolithic biofilms comprised predominantly of oxygenic and anoxygenic phototrophs, sulfate-reducing bacteria, and bacteria from the phylum Bacteroidetes. Biofilm-supported deposits developed in lower-salinity subaqueous environments where light and low water-column turbulence supported dense benthic microbial communities comprised mainly of oxygenic phototrophs. In these settings, gypsum granules precipitated in the extracellular polymeric substance (EPS) matrix as individual granules exhibiting distinctive morphologies. Clastic surfaces developed in sabkha mudflats that included gypsum, carbonate, and siliclastic particles with thin gypsum/biofilm components. Clastic surfaces were influenced by subsurface brine sheets and capillary evaporation and precipitated subsedimentary gypsum discs in deeper regions. Biofilms appeared to influence both chemical and physical sedimentary processes in the various subaqueous and subaerially exposed environments studied. Biofilm interaction with chemical sedimentary processes included dissolution and granularization of precipitation surfaces, formation of

  2. Low power gas discharge plasma mediated inactivation and removal of biofilms formed on biomaterials.

    Science.gov (United States)

    Traba, Christian; Chen, Long; Liang, Jun F

    2013-03-20

    The antibacterial activity of gas discharge plasma has been studied for quiet some time. However, high biofilm inactivation activity of plasma was only recently reported. Studies indicate that the etching effect associated with plasmas generated represent an undesired effect, which may cause live bacteria relocation and thus contamination spreading. Meanwhile, the strong etching effects from these high power plasmas may also alter the surface chemistry and affect the biocompatibility of biomaterials. In this study, we examined the efficiency and effectiveness of low power gas discharge plasma for biofilm inactivation and removal. Among the three tested gases, oxygen, nitrogen, and argon, discharge oxygen demonstrated the best anti-biofilm activity because of its excellent ability in killing bacteria in biofilms and mild etching effects. Low power discharge oxygen completely killed and then removed the dead bacteria from attached surface but had negligible effects on the biocompatibility of materials. DNA left on the regenerated surface after removal of biofilms did not have any negative impact on tissue cell growth. On the contrary, dramatically increased growth was found for these cells seeded on regenerated surfaces. These results demonstrate the potential applications of low power discharge oxygen in biofilm treatments of biomaterials and indwelling device decontaminations. PMID:23894232

  3. Functional analysis of stress protein data in a flor yeast subjected to a biofilm forming condition

    Science.gov (United States)

    Moreno-García, Jaime; Mauricio, Juan Carlos; Moreno, Juan; García-Martínez, Teresa

    2016-01-01

    In this data article, an OFFGEL fractionator coupled to LTQ Orbitrap XL MS equipment and a SGD filtering were used to detect in a biofilm-forming flor yeast strain, the maximum possible number of stress proteins under the first stage of a biofilm formation conditions (BFC) and under an initial stage of fermentation used as reference, so-called non-biofilm formation condition (NBFC). Protein functional analysis – based on cellular components and biological process GO terms – was performed for these proteins through the SGD Gene Ontology Slim Mapper tool. A detailed analysis and interpretation of the data can be found in “Stress responsive proteins of a flor yeast strain during the early stages of biofilm formation” [1]. PMID:27104213

  4. Biofilm forming and leaching mechanism during bioleaching chalcopyrite by Thiobacillus ferrooxidans

    Institute of Scientific and Technical Information of China (English)

    傅建华; 胡岳华; 邱冠周; 柳建设; 徐竞

    2004-01-01

    The mechanism of attachment and leaching of thiobacillus ferrooxcidans (T. f. ) on chalcopyrite were studied. The shaking flasks with bacteria were observed by SEM. The process of T. f attached to the surface of the mineral sample and the biofilm forming were described. The promoting role of the biofilm for bioleaching was discussed. The existence of Fe2+ in the exopolysaccharide layer of T. f was demonstrated by EM(electronic microscope)cell-chemistry analysis. These results show that under the proper growth condition of bacteria, bioleaching of chalcopyrite results in the formation of complete biofilm after 2 - 3 weeks. There are iron ions in the outer layer polymer of T. f. , which provides the micro-environment for themselves, and can guaruntee the energy needed for the bacteria growth in the biofilm. At the same time, Fe3+ ions produced oxidize sulfide which brings about the increase of both growth rate of the bacterial and leaching rate of sulfide minerals.

  5. Biofilm

    Czech Academy of Sciences Publication Activity Database

    Kvíderová, Jana

    Berlin: Springer, 2015 - (Amils, R.; Gargaud, M.; Cernicharo Quintanilla, J.; James Claves, H.; Irvine, W.; Pinti, D.; Viso, M.), s. 1-3 ISBN 978-3-642-27833-4 Institutional support: RVO:67985939 Keywords : biofilm * microbial mat * astrobiology Subject RIV: EF - Botanics

  6. Biofilm-forming capacity in biogenic amine-producing bacteria isolated from dairy products.

    Directory of Open Access Journals (Sweden)

    Maria eDiaz

    2016-05-01

    Full Text Available Biofilms on the surface of food industry equipment are reservoirs of potentially food-contaminating bacteria - both spoilage and pathogenic. However, the capacity of biogenic amine (BA-producers to form biofilms has remained largely unexamined. BAs are low molecular weight, biologically active compounds that in food can reach concentrations high enough to be a toxicological hazard. Fermented foods, especially some types of cheese, accumulate the highest BA concentrations of all. The present work examines the biofilm-forming capacity of 56 BA-producing strains belonging to three genera and 10 species (12 Enterococcus faecalis, 6 Enterococcus faecium, 6 Enterococcus durans, 1 Enterococcus hirae, 12 Lactococcus lactis, 7 Lactobacillus vaginalis, 2 Lactobacillus curvatus, 2 Lactobacillus brevis, 1 Lactobacillus reuteri and 7 Lactobacillus parabuchneri, all isolated from dairy products. Strains of all the tested species - except for L. vaginalis - were able to produce biofilms on polystyrene and adhered to stainless steel. However, the biomass produced in biofilms was strain-dependent. These results suggest that biofilms may provide a route via which fermented foods can become contaminated by BA-producing microorganisms.

  7. Biofilm-Forming Capacity in Biogenic Amine-Producing Bacteria Isolated from Dairy Products

    Science.gov (United States)

    Diaz, Maria; Ladero, Victor; del Rio, Beatriz; Redruello, Begoña; Fernández, María; Martin, M. Cruz; Alvarez, Miguel A.

    2016-01-01

    Biofilms on the surface of food industry equipment are reservoirs of potentially food-contaminating bacteria—both spoilage and pathogenic. However, the capacity of biogenic amine (BA)-producers to form biofilms has remained largely unexamined. BAs are low molecular weight, biologically active compounds that in food can reach concentrations high enough to be a toxicological hazard. Fermented foods, especially some types of cheese, accumulate the highest BA concentrations of all. The present work examines the biofilm-forming capacity of 56 BA-producing strains belonging to three genera and 10 species (12 Enterococcus faecalis, 6 Enterococcus faecium, 6 Enterococcus durans, 1 Enterococcus hirae, 12 Lactococcus lactis, 7 Lactobacillus vaginalis, 2 Lactobacillus curvatus, 2 Lactobacillus brevis, 1 Lactobacillus reuteri, and 7 Lactobacillus parabuchneri), all isolated from dairy products. Strains of all the tested species - except for L. vaginalis—were able to produce biofilms on polystyrene and adhered to stainless steel. However, the biomass produced in biofilms was strain-dependent. These results suggest that biofilms may provide a route via which fermented foods can become contaminated by BA-producing microorganisms. PMID:27242675

  8. The In Vitro Susceptibility of Biofilm Forming Medical Device Related Pathogens to Conventional Antibiotics

    Directory of Open Access Journals (Sweden)

    Garry Laverty

    2014-01-01

    Full Text Available Minimum inhibitory concentration (MIC, minimum bactericidal concentration (MBC, and minimum biofilm eradication concentration (MBEC and kill kinetics were established for vancomycin, rifampicin, trimethoprim, gentamicin, and ciprofloxacin against the biofilm forming bacteria Staphylococcus epidermidis (ATCC 35984, Staphylococcus aureus (ATCC 29213, Methicillin Resistant Staphylococcus aureus (MRSA (ATCC 43300, Pseudomonas aeruginosa (PAO1, and Escherichia coli (NCTC 8196. MICs and MBCs were determined via broth microdilution in 96-well plates. MBECs were studied using the Calgary Biofilm Device. Values obtained were used to investigate the kill kinetics of conventional antimicrobials against a range of planktonic and biofilm microorganisms over a period of 24 hours. Planktonic kill kinetics were determined at 4xMIC and biofilm kill kinetics at relative MBECs. Susceptibility of microorganisms varied depending on antibiotic selected and phenotypic form of bacteria. Gram-positive planktonic isolates were extremely susceptible to vancomycin (highest MBC: 7.81 mg L−1: methicillin sensitive and resistant S. aureus but no MBEC value was obtained against all biofilm pathogens tested (up to 1000 mg L−1. Both gentamicin and ciprofloxacin displayed the broadest spectrum of activity with MIC and MBCs in the mg L−1 range against all planktonic isolates tested and MBEC values obtained against all but S. epidermidis (ATCC 35984 and MRSA (ATCC 43300.

  9. Microbial Biofilms in Endodontic Infections: An Update Review

    Directory of Open Access Journals (Sweden)

    Zahed Mohammadi

    2013-04-01

    Full Text Available Biofilms and microbial aggregates are the common mechanisms for the survival of bacteria in nature. In other words, the ability to form biofilms has been regarded as a virulence factor. Microbial biofilms play an essential role in several infectious diseases such as pulp and periradicular pathosis. The aim of this article was to review the adaptation mechanisms of biofilms, their roles in pulpal and periapical pathosis, factors influencing biofilm formation, mechanisms of their antimicrobial resistance, models developed to create biofilms, observation techniques of endodontic biofilms, and the effects of root canal irrigants and medicaments as well as lasers on endodontic biofilms. The search was performed from 1982 to December 2010, and was limited to papers in English language. The keywords searched on Medline were "biofilms and endodontics," "biofilms and root canal irrigation," "biofilms and intra-canal medicament," and "biofilms and lasers." The reference section of each article was manually searched to find other suitable sources of information.

  10. Antibacterial activity of Espand (Peganum harmala alcoholic extracts against six pathogenic bacteria in planktonic and biofilm forms

    Directory of Open Access Journals (Sweden)

    Zinab Mohsenipour

    2016-03-01

    Full Text Available Introduction: Microbial biofilms have attracted interest in recent years because they have become the most important cause of nosocomial infections. This study was aimed to examine the antibacterial activities of Peganum harmala extracts on the development of microbial biofilms and planktonic form of six pathogenic bacteria which include Staphylococcus aureus, Bacillus cereus, Streptococcus pneumoniae, Pseudomonas aeruginosa, Escherichia coli and Klebsiella pneumoniae. Materials and methods: Antimicrobial activities of the crude extracts against the planktonic form of bacteria were evaluated by using disc diffusion method, minimum inhibitory concentration (MIC and the minimum bactericidal concentration (MBC values were determined by a macrobroth dilution technique. Anti- biofilm effects of the extracts were assessed by microtiter plate method. Results: According to the results, P. harmala extracts could inhibit test bacteria in planktonic form. To inhibit biofilm formation, biofilm metabolic activity and eradication of established biofilms, efficiency of the extracts depended on concentration. The highest inhibitory effects of P. harmala extracts were observed on biofilm formation of S. aureus (90.28% also, the greatest demolish were observed on S. pneumonia biofilm (77.76%. These extracts cause dramatically decrease the metabolic activity of bacteria in biofilm structures, in this case the decrement of B. cereus were highest (69.98% compared to other tested bacteria. Discussion and conclusion: Therefore, it can be suggested that P.harmala extracts applied as antimicrobial agents against testing bacteria particularly in biofilm forms

  11. Microbial Biofilms in Endodontic Infections: An Update Review

    OpenAIRE

    Zahed Mohammadi; Flavio Palazzi; Luciano Giardino; Sousan Shalavi

    2013-01-01

    Biofilms and microbial aggregates are the common mechanisms for the survival of bacteria in nature. In other words, the ability to form biofilms has been regarded as a virulence factor. Microbial biofilms play an essential role in several infectious diseases such as pulp and periradicular pathosis. The aim of this article was to review the adaptation mechanisms of biofilms, their roles in pulpal and periapical pathosis, factors influencing biofilm formation, mechanisms of their antimicrobial ...

  12. Cell surface hydrophobicity and biofilm formation ability of Vibrio splendidus%灿烂弧菌的疏水性和生物被膜形成能力

    Institute of Scientific and Technical Information of China (English)

    李华; 王扬; 李强; 乔帼

    2011-01-01

    the motility of the flagellum and measured pill and cell surface hydrophobicity using tests for salt-aggregation (SAT) and microbial adherence to hydrocarbons (MATH). V. Splendidus AP622 possesses a high ability to form a biofilm. The biofilm formation cycle was 24 h in length and the optimal formation conditions consisted of polyvinyl chloride (PVC) and LB medium with 0.5% glucose. Swarming and twitching motilities played an important role in biofilm formation. The resistance of re-suspended biofilm bacteria to antibiotics was significantly higher than in planktonic bacteria (P50%. In conclusion, the hydrophobicity and biofilm formation properties suggest that V. Splendidus AP622 has strong adhesion properties. Resistance to antibiotics as a result of biofilm formation will reduce the effectiveness of treatments in aquaculture facilities. Thus, cell surface hydrophobicity and biofilm formation play an important role in the pathogenesis of V. Splendidus.

  13. Proteomic analysis of matrix of dental biofilm formed under dietary carbohydrate exposure.

    Science.gov (United States)

    Moi, G P; Cury, J A; Dombroski, T C D; Pauletti, B A; Paes Leme, A F

    2012-01-01

    To evaluate whether protein changes in extracellular matrix of dental biofilm are a unique property of sucrose, this in situ study was conducted using as active control glucose and fructose, the sucrose monosaccharide constituents. Proteins were analyzed by two-dimensional electrophoresis followed by LC-MS/MS after trypsin digestion. Absence or lower abundance of calcium-binding proteins and higher abundance of prolactin-induced proteins were found in biofilm formed in the presence of sucrose or its monosaccharide constituents compared with water, the negative control group. The data suggest that besides sucrose, other dietary carbohydrates may also provoke a change in the protein profile of extracellular matrix of dental biofilm formed. PMID:22614073

  14. Biofilm-producing ability and efficiency of sanitizing agents against Prototheca zopfii isolates from bovine subclinical mastitis.

    Science.gov (United States)

    Gonçalves, Juliano Leonel; Lee, Sarah Hwa In; de Paula Arruda, Eurico; Pedroso Galles, Débora; Camargo Caetano, Vinícius; Fernandes de Oliveira, Carlos Augusto; Fernandes, Andrezza Maria; Veiga dos Santos, Marcos

    2015-06-01

    The objectives of the present study were to evaluate (1) the capacity of the microalga Prototheca zopfii isolated from subclinical bovine mastitis cases to form biofilms; and (2) the resistance of these isolates to sanitizing agents. Ten isolates of P. zopfii from cows with subclinical mastitis (somatic cell count>200×10(3) cells/mL), distributed in 5 dairy farms, were evaluated for their capacity to form biofilms in polystyrene microplate assays and stainless steel coupons, at 25°C and 37°C±1°C. Prototheca zopfii were isolated from milk samples via microbiological culture and analyzed by 18S rRNA gene sequencing. Biofilm formation on the coupons was observed by scanning electron microscopy. The resistance to sanitizing agents was assessed using the biofilm-forming P. zopfii isolates in stainless steel coupon assays, which were subjected to 3 sanitizers: peracetic acid, sodium hypochlorite, and iodine solution. To evaluate resistance to the sanitizers, the minimum inhibitory concentration (MIC) technique was performed using decreasing concentrations of the sanitizing agents (20, 10, 5, 2.5, 1.25, 0.625, 0.312, 0.156, 0.078, 0.039, and 0.019 g/L). After inoculating the isolates, all concentrations were evaluated at 3 distinct incubation periods (24, 48, and 72 h) to assess the effect of incubation time on the MIC. Using the polystyrene microplate assays, 1 isolate showed weak biofilm production, 5 moderate, and 4 strong, when incubated at 25°C±1. For isolates incubated at 37°C±1, 6 showed weak biofilm production and 4 moderate. All P. zopfii isolates (n=10) had the capacity to form biofilms on stainless steel coupons. The longer the incubation period of the P. zopfii isolates at different dilutions, the greater the concentrations of sanitizer needed to prevent growth of the microalgae under the tested conditions. We detected a significant effect of sanitizer and time of incubation (24, 48, and 72 h) on MIC values against P. zopfii isolates. The isolates

  15. Meningococcal biofilm formation

    DEFF Research Database (Denmark)

    Lappann, M.; Haagensen, Janus Anders Juul; Claus, H.;

    2006-01-01

    We show that in a standardized in vitro flow system unencapsulated variants of genetically diverse lineages of Neisseria meningitidis formed biofilms, that could be maintained for more than 96 h. Biofilm cells were resistant to penicillin, but not to rifampin or ciprofloxacin. For some strains......, microcolony formation within biofilms was observed. Microcolony formation in strain MC58 depended on a functional copy of the pilE gene encoding the pilus subunit pilin, and was associated with twitching of cells. Nevertheless, unpiliated pilE mutants formed biofilms showing that attachment and accumulation...... PilX alleles was identified among genetically diverse meningococcal strains. PilX alleles differed in their propensity to support autoaggregation of cells in suspension, but not in their ability to support microcolony formation within biofilms in the continuous flow system....

  16. Chemical sanitizers to control biofilms formed by two Pseudomonas species on stainless steel surface

    OpenAIRE

    Danila Soares Caixeta; Thiago Henrique Scarpa; Danilo Florisvaldo Brugnera; Dieyckson Osvani Freire; Eduardo Alves; Luiz Ronaldo de Abreu; Roberta Hilsdorf Piccoli

    2012-01-01

    The biofilm formation of Pseudomonas aeruginosa and Pseudomonas fluorescens on AISI 304 stainless steel in the presence of reconstituted skim milk under different temperatures was conducted, and the potential of three chemical sanitizers in removing the mono-species biofilms formed was compared. Pseudomonas aeruginosa cultivated in skim milk at 28 °C presented better growth rate (10.4 log CFU.mL-1) when compared with 3.7 and 4.2 log CFU.mL-1 for P. aeruginosa and P. fluorescens cultivated at ...

  17. Polysaccharides serve as scaffold of biofilms formed by mucoid Pseudomonas aeruginosa

    DEFF Research Database (Denmark)

    Yang, Liang; Hengzhuang, Wang; Wu, Hong;

    2012-01-01

    Chronic lung infection by mucoid Pseudomonas aeruginosa is one of the major pathologic features in patients with cystic fibrosis. Mucoid P. aeruginosa is notorious for its biofilm forming capability and resistance to immune attacks. In this study, the roles of extracellular polymeric substances f...

  18. Identification of individual biofilm-forming bacterial cells using Raman tweezers

    Science.gov (United States)

    Samek, Ota; Bernatová, Silvie; Ježek, Jan; Šiler, Martin; Šerý, Mojmir; Krzyžánek, Vladislav; Hrubanová, Kamila; Zemánek, Pavel; Holá, Veronika; Růžička, Filip

    2015-05-01

    A method for in vitro identification of individual bacterial cells is presented. The method is based on a combination of optical tweezers for spatial trapping of individual bacterial cells and Raman microspectroscopy for acquisition of spectral "Raman fingerprints" obtained from the trapped cell. Here, Raman spectra were taken from the biofilm-forming cells without the influence of an extracellular matrix and were compared with biofilm-negative cells. Results of principal component analyses of Raman spectra enabled us to distinguish between the two strains of Staphylococcus epidermidis. Thus, we propose that Raman tweezers can become the technique of choice for a clearer understanding of the processes involved in bacterial biofilms which constitute a highly privileged way of life for bacteria, protected from the external environment.

  19. Role of biofilm in protection of the replicative form of Legionella pneumophila.

    Science.gov (United States)

    Andreozzi, Elisa; Di Cesare, Andrea; Sabatini, Luigia; Chessa, Elisa; Sisti, Davide; Rocchi, Marco; Citterio, Barbara

    2014-12-01

    The dual nature of Legionella pneumophila enables its survival in free and intracellular environments and underpins its infection and spread mechanisms. Experiments using bacterial cultures and improved RTqPCR protocols were devised to gain fresh insights into the role of biofilm in protecting the replicative form of L. pneumophila. mip gene expression was used as a marker of virulence in sessile (biofilm-bound) and planktonic (free-floating) cells of L. pneumophila serotype 1 ATCC 33152. The ratio of mip gene expression to transcriptionally active Legionella cells increased both in sessile and free-floating cells demonstrating an up-regulation of mip gene under nutrient depletion. However, a different trend was observed between the two forms, in planktonic cells the mip gene expression/transcriptionally active Legionella cells increased until the end of the experiment, while in the biofilm such increase was observed at the end of the experiment. These findings suggest a possible association between the switch to the transmissive phase of Legionella and a mip up-regulation and a role for biofilm in preserving Legionella cells in replicative form. Moreover, it has been shown that improved RTqPCR protocols are valuable tools to explore bacterial virulence. PMID:25023637

  20. Assessing Algebraic Solving Ability Of Form Four Students

    Directory of Open Access Journals (Sweden)

    Lim Hooi Lian

    2006-10-01

    Full Text Available Mathematics researchers generally agree that algebra is a tool for problem solving, a method of expressing relationship, analyzing and representing patterns, and exploring mathematical properties in a variety of problem situations. Thus, several mathematics researchers and educators have focused on investigating the introduction and the development of algebraic solving abilities. However research works on assessing students' algebraic solving ability is sparse in literature. The purpose of this study was to use the SOLO model as a theoretical framework for assessing Form Four students' algebraic solving abilities in using linear equation. The content domains incorporated in this framework were linear pattern (pictorial, direct variations, concepts of function and arithmetic sequence. This study was divided into two phases. In the first phase, students were given a pencil-and-paper test. The test comprised of eight superitems of four items each. Results were analyzed using a Partial Credit model. In the second phase, clinical interviews were conducted to seek the clarification of the students' algebraic solving processes. Results of the study indicated that 62% of the students have less than 50% probability of success at relational level. The majority of the students in this study could be classified into unistructural and multistructural. Generally, most of the students encountered difficulties in generalizing their arithmetic thinking through the use of algebraic symbols. The qualitative data analysis found that the high ability students seemed to be more able to seek the recurring linear pattern and identify the linear relationship between variables. They were able to co-ordinate all the information given in the question to form the algebraic expression and linear equations. Whereas, the low ability students showed an ability more on drawing and counting method. They lacked understanding of algebraic concepts to express the relationship

  1. Lucilia sericata Chymotrypsin Disrupts Protein Adhesin-Mediated Staphylococcal Biofilm Formation

    OpenAIRE

    Harris, Llinos G.; Nigam, Yamni; Sawyer, James; Mack, Dietrich; Pritchard, David I.

    2013-01-01

    Staphylococcus aureus and Staphylococcus epidermidis biofilms cause chronic infections due to their ability to form biofilms. The excretions/secretions of Lucilia sericata larvae (maggots) have effective activity for debridement and disruption of bacterial biofilms. In this paper, we demonstrate how chymotrypsin derived from maggot excretions/secretions disrupts protein-dependent bacterial biofilm formation mechanisms.

  2. Chemical sanitizers to control biofilms formed by two Pseudomonas species on stainless steel surface

    Directory of Open Access Journals (Sweden)

    Danila Soares Caixeta

    2012-03-01

    Full Text Available The biofilm formation of Pseudomonas aeruginosa and Pseudomonas fluorescens on AISI 304 stainless steel in the presence of reconstituted skim milk under different temperatures was conducted, and the potential of three chemical sanitizers in removing the mono-species biofilms formed was compared. Pseudomonas aeruginosa cultivated in skim milk at 28 °C presented better growth rate (10.4 log CFU.mL-1 when compared with 3.7 and 4.2 log CFU.mL-1 for P. aeruginosa and P. fluorescens cultivated at 7 °C, respectively. Pseudomonas aeruginosa formed biofilm when cultivated at 28 °C. However, only the adhesion of P. aeruginosa and P. fluorescens was observed when incubated at 7 °C. The sodium dichloroisocyanurate was the most efficient sanitizer in the reduction of the adhered P. aeruginosa cells at 7 and 28 °C and those on the biofilm, respectively. The hydrogen peroxide was more effective in the reduction of adhered cells of P. fluorescens at 7 °C.

  3. Bisphosphocins: novel antimicrobials for enhanced killing of drug-resistant and biofilm-forming bacteria.

    Science.gov (United States)

    Wong, Jonathan P; DiTullio, Paul; Parkinson, Steve

    2015-01-01

    The global prevalence of antibiotic resistance and the threat posed by drug-resistant superbugs are a leading challenge confronting modern medicine in the 21st century. However, the progress on the development of novel antibiotics to combat this problem is severely lagging. A more concerted effort to develop novel therapeutic agents with robust activity and unique mechanisms of action will be needed to overcome the problem of drug resistance. Furthermore, biofilm forming bacteria are known to be increasingly resistant to the actions of antibiotics and are a leading cause of mortality or morbidity in nosocomial infections. Bisphosphocins (also scientifically known as nubiotics) are novel small protonated deoxynucleotide molecules, and exert their antibacterial activity by depolarization of the bacterial cell membrane, causing bacterial cell death. Bisphosphocins may represent an effective weapon against antibiotic-resistant and biofilm-forming pathogenic bacteria. Preclinical efficacy studies in animals have shown that the compounds are safe and, efficacious against various bacterial infections, including drug-resistant pathogens. In vitro biochemical analysis confirmed that the bactericidal activity of bisphosphocins is mediated by depolarization of the bacterial cell membrane, and these compounds are better able to penetrate through bacterial biofilm and kill the biofilm encased bacteria. This article will cover the structure, mode of action, safety, efficacy and the current state of development of bisphosphocins. Together, the information presented here will present a strong case for bisphosphocins to be considered for use as new weapons to complement the existing arsenal of antimicrobial drugs and as a first line defence against drug-resistant and biofilm-forming bacteria. PMID:26597426

  4. Application of bacteriophages to reduce biofilms formed by hydrogen sulfide producing bacteria on surfaces in a rendering plant.

    Science.gov (United States)

    Gong, Chao; Jiang, Xiuping

    2015-08-01

    Hydrogen sulfide producing bacteria (SPB) in raw animal by-products are likely to grow and form biofilms in the rendering processing environments, resulting in the release of harmful hydrogen sulfide (H2S) gas. The objective of this study was to reduce SPB biofilms formed on different surfaces typically found in rendering plants by applying a bacteriophage cocktail. Using a 96-well microplate method, we determined that 3 SPB strains of Citrobacter freundii and Hafnia alvei are strong biofilm formers. Application of 9 bacteriophages (10(7) PFU/mL) from families of Siphoviridae and Myoviridae resulted in a 33%-70% reduction of biofilm formation by each SPB strain. On stainless steel and plastic templates, phage treatment (10(8) PFU/mL) reduced the attached cells of a mixed SPB culture (no biofilm) by 2.3 and 2.7 log CFU/cm(2) within 6 h at 30 °C, respectively, as compared with 2 and 1.5 log CFU/cm(2) reductions of SPB biofilms within 6 h at 30 °C. Phage treatment was also applied to indigenous SPB biofilms formed on the environmental surface, stainless steel, high-density polyethylene plastic, and rubber templates in a rendering plant. With phage treatment (10(9) PFU/mL), SPB biofilms were reduced by 0.7-1.4, 0.3-0.6, and 0.2-0.6 log CFU/cm(2) in spring, summer, and fall trials, respectively. Our study demonstrated that bacteriophages could effectively reduce the selected SPB strains either attached to or in formed biofilms on various surfaces and could to some extent reduce the indigenous SPB biofilms on the surfaces in the rendering environment. PMID:26102989

  5. Efficiency of different sanitation methods on Listeria monocytogenes biofilms formed under various environmental conditions.

    Science.gov (United States)

    Belessi, Charalambia-Eirini A; Gounadaki, Antonia S; Psomas, Antonios N; Skandamis, Panagiotis N

    2011-03-01

    The resistance of Listeria monocytogenes biofilms formed under food processing conditions, against various sanitizing agents and disinfection procedures was evaluated in the present study. The first sanitation procedure included biofilm formation on stainless steel coupons (SS) placed in tryptic soy broth supplemented with 0.6% yeast extract (TSBYE) of various concentrations of NaCl (0.5, 7.5 and 9.5%) at different temperatures (5 and 20 °C). The biofilms formed were exposed to warm (60 °C) water for 20 min, or to peroxyacetic acid (2% PAA) for 1, 2, 3 and 6 min. Treatment with warm water caused no significant (P ≥ 0.05) reductions in the attached populations. Conversely, surviving bacteria on SS coupons decreased as the exposure time to 2% PAA increased and could not be detected by culture after 6 min of exposure. Biofilms formed at 20°C were more resistant to PAA than biofilms formed at 5 °C. Salt concentration in the growth medium had no marked impact on the resistance to PAA. The second sanitation procedure included biofilm formation of nonadapted (NA) and acid-adapted (AA) cells in TSBYE of pH 5.0 and 7.0 (i.e., NA-5.0, NA-7.0 and AA-5.0, AA-7.0) at 4 °C. Coupons bearing attached cells of L. monocytogenes were periodically exposed to chlorine (0.465% Cl(-)), quaternary ammonium compound (1% QAC) and 2% PAA. The resistance of attached cells to QAC, PAA and Cl(-) followed the order: AA-5.0>NA-7.0 ≥ AA-7.0>NA-5.0. The most effective sanitizer was QAC followed by PAA and Cl(-). The results can lead to the development of efficient sanitation strategies in order to eliminate L. monocytogenes from the processing environment. Furthermore, such results may explain the presence of L. monocytogenes after sanitation as a result of cell attachment history. PMID:21093085

  6. Influence of Streptococcus mutans on Enterococcus faecalis Biofilm Formation

    NARCIS (Netherlands)

    Deng, Dong Mei; Hoogenkamp, Michel A.; Exterkate, Rob A. M.; Jiang, Lei Meng; van der Sluis, Lucas W. M.; ten Cate, Jacob M.; Crielaard, Wim

    2009-01-01

    Introduction: An important virulence factor of Enterococcus faecalis is its ability to form biofilms. Most studies on biofilm formation have been carried out by using E. faecalis monocultures. Given the polymicrobial nature of root canal infections, it is important to understand biofilm formation of

  7. Glass forming ability of soda lime borate Liquids

    OpenAIRE

    Zheng, Qiuju; Mauro, J. C.; Smedskjær, Morten Mattrup; Potuzak, M.; Keding, Ralf; Yue, Yuanzheng

    2010-01-01

    We investigate the composition dependence of glass-forming ability (GFA) of a series of iron-containing soda lime borate liquids by substituting Na2O for B2O3. We have characterized GFA by measuring the glass stability against crystallization using a differential scanning calorimeter (DSC). The results show that the GFA decreases when substituting Na2O for B2O3. Moreover, we find that there is no direct link between the kinetic fragility and GFA for the soda lime borate series studied herein....

  8. Biofilm producing multidrug resistant Acinetobacter species from a tertiary care hospital: a therapeutic challenge

    Directory of Open Access Journals (Sweden)

    Manju Bala

    2016-07-01

    Conclusions: This study demonstrates the ability of Acinetobacter isolates to form biofilm and biofilm production has strong association with multiple drug resistance. [Int J Res Med Sci 2016; 4(7.000: 3024-3026

  9. Efficacy of Various Chemical Disinfectants on Biofilms Formed in Spacecraft Potable Water System Component

    Science.gov (United States)

    Wong, Willy; Garcia, Veronica; Castro, Victoria; Ott, Mark; Duane

    2009-01-01

    As the provision of potable water is critical for successful habitation of the International Space Station (ISS), life support systems were installed in December 2008 to recycle both humidity from the atmosphere and urine to conserve available water in the vehicle. Pre-consumption testing from the dispensing needle at the Potable Water Dispenser (PWD) indicated that bacterial concentrations exceeded the current ISS specifications of 50 colony forming units (CFU) per ml. Subsequent investigations revealed that a corrugated stainless steel flex hose upstream of the dispensing needle in the PWD was filled with non-sterile water and left at room temperature for over one month before launch. To simulate biofilm formation that was suspected in the flight system, sterile flex hoses were seeded with a consortium of bacterial isolates previously recovered from other ISS water systems, which included Ralstonia pickettii, Burkholderia multivorans, Caulobacter vibrioides., and Cupriavidus pauculus. After 5 days of incubation, these hoses were challenged with various chemical disinfectants including hydrogen peroxide, colloidal silver, and buffered pH solutions to determine the ability of the disinfectants to decrease and maintain bacterial concentrations below ISS specifications. Disinfection efficacy over time was measured by collecting daily heterotrophic plate counts following exposure to the disinfectants. A single flush with either 6% hydrogen peroxide solution or a mixture of 3% hydrogen peroxide and 400 ppb colloidal silver effectively reduced the bacterial concentrations to less than 1 CFU/ml for a period of up to 2 months. Testing results indicated that hydrogen peroxide and mixtures of hydrogen peroxide and colloidal silver have tremendous potential as alternative disinfectants for ISS water systems.

  10. Antimicrobial flavonoids isolated from Indian medicinal plant Scutellaria oblonga inhibit biofilms formed by common food pathogens.

    Science.gov (United States)

    Rajendran, Narendran; Subramaniam, Shankar; Christena, Lowrence Rene; Muthuraman, Meenakshi Sundaram; Subramanian, Nagarajan Sai; Pemiah, Brindha; Sivasubramanian, Aravind

    2016-09-01

    Scutellaria oblonga Benth., a hitherto phytochemically unexplored Indian medicinal folklore plant was extracted with acetone and subjected to chromatography to yield nine flavonoids, for the first time from this plant. Antimicrobial assays were performed against 11 foodborne pathogens, and three molecules (Techtochrysin, Negletein and Quercitin-3-glucoside) depicted significant activity. These molecules were assessed for their rate of antibacterial action using time-kill curves which depicted complete inhibition of most of the bacteria within 12-16 h. The significant biofilm-reducing capability exhibited by these three molecules formed a significant finding of the current study. In most of the experiments, a 90-95% reduction in biofilms was observed. Thus, flavonoids as natural molecules from S. oblonga could be further researched to be used as potent antimicrobial and antibiofilm agents. PMID:26508034

  11. The capacity of Listeria monocytogenes mutants with in-frame deletions in putative ATP-binding cassette transporters to form biofilms and comparison with the wild type

    Directory of Open Access Journals (Sweden)

    Marina Ceruso

    2014-02-01

    Full Text Available Listeria monocytogenes (Lm is a food-borne pathogen responsible for human listeriosis, an invasive infection with high mortality rates. Lm has developed efficient strategies for survival under stress conditions such as starvation and wide variations in temperature, pH, and osmolarity. Therefore, Lm can survive in food under multiple stress conditions. Detailed studies to determine the mode of action of this pathogen for survival under stress conditions are important to control Lm in food. It has been shown that genes encoding for ATP-binding cassette (ABC transporters are induced in Lm in food, in particular under stress conditions. Previous studies showed that these genes are involved in sensitivity to nisin, acids, and salt. The aim of this study was to determine the involvement of some ABC transporters in biofilm formation. Therefore, deletion mutants of ABC transporter genes (LMOf2365_1875 and LMOf2365_1877 were created in Lm F2365, and then were compared to the wild type for their capacity to form biofilms. Lm strain F2365 was chosen as reference since the genome is fully sequenced and furthermore this strain is particularly involved in food-borne outbreaks of listeriosis. Our results showed that DLMOf2365_1875 had an increased capacity to form biofilms compared to the wild type, indicating that LMOf2365_1875 negatively regulates biofilm formation. A deeper knowledge on the ability to form biofilms in these mutants may help in the development of intervention strategies to control Lm in food and in the environment.

  12. Long-Term Succession of Structure and Diversity of a Biofilm Formed in a Model Drinking Water Distribution System

    OpenAIRE

    A. C. Martiny; T. M. Jorgensen; Albrechtsen, H.-J.; Arvin, E; Molin, S.

    2003-01-01

    In this study, we examined the long-term development of the overall structural morphology and community composition of a biofilm formed in a model drinking water distribution system with biofilms from 1 day to 3 years old. Visualization and subsequent quantification showed how the biofilm developed from an initial attachment of single cells through the formation of independent microcolonies reaching 30 μm in thickness to a final looser structure with an average thickness of 14.1 μm and coveri...

  13. Microtiter Plate Assay for Assessment of Listeria monocytogenes Biofilm Formation

    OpenAIRE

    Djordjevic, D.; Wiedmann, M.; McLandsborough, L. A.

    2002-01-01

    Listeria monocytogenes has the ability to form biofilms on food-processing surfaces, potentially leading to food product contamination. The objective of this research was to standardize a polyvinyl chloride (PVC) microtiter plate assay to compare the ability of L. monocytogenes strains to form biofilms. A total of 31 coded L. monocytogenes strains were grown in defined medium (modified Welshimer's broth) at 32°C for 20 and 40 h in PVC microtiter plate wells. Biofilm formation was indirectly a...

  14. Characterization of biofilm-like structures formed by Pseudomonas aeruginosa in a synthetic mucus medium

    Directory of Open Access Journals (Sweden)

    Haley Cecily L

    2012-08-01

    Full Text Available Abstract Background The accumulation of thick stagnant mucus provides a suitable environment for the growth of Pseudomonas aeruginosa and Staphylococcus aureus within the lung alveoli of cystic fibrosis (CF patients. These infections cause significant lung damage, leading to respiratory failure and death. In an artificial mucin containing medium ASM+, P. aeruginosa forms structures that resemble typical biofilms but are not attached to any surface. We refer to these structures as biofilm like structures (BLS. Using ASM+ in a static microtiter plate culture system, we examined the roles of mucin, extracellular DNA, environmental oxygen (EO2, and quorum sensing (QS in the development of biofilm-like structures (BLS by P. aeruginosa; and the effect of EO2 and P. aeruginosa on S. aureus BLS. Results Under 20% EO2, P. aeruginosa strain PAO1 produced BLS that resemble typical biofilms but are confined to the ASM+ and not attached to the surface. Levels of mucin and extracellular DNA within the ASM+ were optimized to produce robust well developed BLS. At 10% EO2, PAO1 produced thicker, more developed BLS, while under 0% EO2, BLS production was diminished. In contrast, the S. aureus strain AH133 produced well-developed BLS only under 20% EO2. In PAO1, loss of the QS system genes rhlI and rhlR affected the formation of BLS in ASM+ in terms of both structure and architecture. Whether co-inoculated into ASM+ with AH133, or added to established AH133 BLS, PAO1 eliminated AH133 within 48–56 h. Conclusions The thick, viscous ASM+, which contains mucin and extracellular DNA levels similar to those found in the CF lung, supports the formation of biofilm-like structures similar to the aggregates described within CF airways. Alterations in environmental conditions or in the QS genes of P. aeruginosa, as occurs naturally during the progression of CF lung infection, affect the architecture and quantitative structural features of these BLS. Thus, ASM+ provides an

  15. Effect of Mono and Di-rhamnolipids on Biofilms Pre-formed by Bacillus subtilis BBK006.

    Science.gov (United States)

    De Rienzo, Mayri A Díaz; Martin, Peter J

    2016-08-01

    Different microbial inhibition strategies based on the planktonic bacterial physiology have been known to have limited efficacy on the growth of biofilms communities. This problem can be exacerbated by the emergence of increasingly resistant clinical strains. Biosurfactants have merited renewed interest in both clinical and hygienic sectors due to their potential to disperse microbial biofilms. In this work, we explore the aspects of Bacillus subtilis BBK006 biofilms and examine the contribution of biologically derived surface-active agents (rhamnolipids) to the disruption or inhibition of microbial biofilms produced by Bacillus subtilis BBK006. The ability of mono-rhamnolipids (Rha-C10-C10) produced by Pseudomonas aeruginosa ATCC 9027 and the di-rhamnolipids (Rha-Rha-C14-C14) produced by Burkholderia thailandensis E264, and phosphate-buffered saline to disrupt biofilm of Bacillus subtilis BBK006 was evaluated. The biofilm produced by Bacillus subtilis BBK006 was more sensitive to the di-rhamnolipids (0.4 g/L) produced by Burkholderia thailandensis than the mono-rhamnolipids (0.4 g/L) produced by Pseudomonas aeruginosa ATCC 9027. Rhamnolipids are biologically produced compounds safe for human use. This makes them ideal candidates for use in new generations of bacterial dispersal agents and useful for use as adjuvants for existing microbial suppression or eradication strategies. PMID:27113589

  16. Retention capacity of bio-films formed on the surface of nuclear and basaltic glasses

    International Nuclear Information System (INIS)

    Available in abstract form only. Full text of publication follows: The role of the bacteria in the various compartments of a repository site was still not extensively studied. It is likely that most known bacteria cannot develop on the surface of radioactive materials but one must consider that 10% only of the bacteria species are known. As an example, a research group has recently discovered an isolated community of bacteria nearly two miles underground that derives all of its energy from the decay of radioactive rocks (LIN et al., 2006). It is generally accepted that alterations of rocks and anthropogenic products are not exclusively driven by the interaction with water or mineral aqueous solutions. Organic compounds as well as microorganisms are important in mineral degradation processes, and secondary mineralization. However, the exact role of bio-films in these processes remains unclear. The study of (AOUAD, 2006) will be presented as an example. Two materials were tested: the reference French nuclear glass SON68 17 LIDC2A2Z1 and a tholeiitic basaltic glass (natural analogue). Experiments were carried out for 19 weeks at 25 deg. C. A specific growth medium were developed which allows both the growth of Pseudomonas bacterium and a precise measurement, using ICP-MS, of trace elements solubilized from both glasses (AOUAD et al., 2005) The thickness of bio-films, analyzed by confocal laser microscopy was 40 μm for both materials. These bio-films are able to efficiently trap most of the glass constituents. They also form a protective barrier at the solid/solution interface. (authors)

  17. Diarrhea-associated biofilm formed by enteroaggregative Escherichia coli and aggregative Citrobacter freundii: a consortium mediated by putative F pili

    Directory of Open Access Journals (Sweden)

    Araújo Ana CG

    2010-02-01

    Full Text Available Abstract Background Enteroaggregative Escherichia coli (EAEC are enteropathogenic strains identified by the aggregative adhesion (AA pattern that share the capability to form biofilms. Citrobacter freundii is classically considered as an indigenous intestinal species that is sporadically associated with diarrhea. Results During an epidemiologic study focusing on infantile diarrhea, aggregative C. freundii (EACF and EAEC strains were concomitantly recovered from a severe case of mucous diarrhea. Thereby, the occurrence of synergic events involving these strains was investigated. Coinfection of HeLa cells with EACF and EAEC strains showed an 8-fold increase in the overall bacterial adhesion compared with single infections (P traA were capable of forming bacterial aggregates only in the presence of EACF. Scanning electronic microscopy analyses revealed that bacterial aggregates as well as enhanced biofilms formed by EACF and traA-positive EAEC were mediated by non-bundle forming, flexible pili. Moreover, mixed biofilms formed by EACF and traA-positive EAEC strains were significantly reduced using nonlethal concentration of zinc, a specific inhibitor of F pili. In addition, EAEC strains isolated from diarrheic children frequently produced single biofilms sensitive to zinc. Conclusions Putative F pili expressed by EAEC strains boosted mixed biofilm formation when in the presence of aggregative C. freundii.

  18. Glass Forming Ability of Sub-Alkaline Silicate Melts

    Science.gov (United States)

    Vetere, F. P.; Iezzi, G.; Behrens, H.; Holtz, F.; Ventura, G.; Misiti, V.; Mollo, S.; Perugini, D.

    2014-12-01

    The glass forming ability (GFA) and critical cooling rate (Rc) of six natural sub-alkaline melts from basalt to rhyolite (i.e., B100, B80R20, B60R40, B40R60, B20R80, and R100) have been quantified through cooling-induced solidification experiments of 9000, 1800, 180, 60, 7 and 1 °C/h conducted at ambient pressure and air buffering conditions, in a temperature range between 1300 °C (superliquidus region) and 800 °C (glass transition region), The phase proportion in each run-product was determined by image analysis on about 500 BS-SEM microphotographs. The phase assemblage consists of glass, clinopyroxene, spinel, and plagioclase with the occurrence of sporadic olivine, orthopyroxene and melilite. Both the glass and crystalline fractions are well correlated with the composition of residual melt. Generally, the amount of crystals decreases with increasing cooling rate. However, some exceptions occurs showing no correlations or even opposite trends. For the example of, Al2O3 and CaO in clinopyroxenes from B100, B80R20, B60R40 and B40R60, their concentrations scale as a function of both cooling rate and the degree of clinopyroxene crystallization. The value of Rc changes of 5 order of magnitude from retrieve the solidification conditions of aphyric, degassed and oxidised lavas. Indeed, the relationship between crystal content and cooling kinetics suggests that the solidification path is more complex than previously assumed and strongly non-linear. This finding has also implications to design glass-ceramics based on natural, accessible and low-cost starting materials.

  19. TOPICAL REVIEW On the glass forming ability of liquid alloys

    Directory of Open Access Journals (Sweden)

    Yoshio Waseda et al

    2008-01-01

    Full Text Available By using the concepts of the short-range order (SRO and middle-range order (MRO characterizing structures, an attempt has been made to describe the glass forming ability (GFA of liquid alloys. This includes the effect of more than two kinds of SRO in the liquid caused by the addition of second and third elements to a metallic solvent. The minimum solute concentration is related to the atomic volume mismatch estimated from the cube of the atomic radius. The optimum solute concentration for good glass formability in several binary and some ternary alloys is discussed on the basis of the empirical guideline. A new approach to obtaining good GFA of liquid alloys is based on four main factors: (i formation of new SRO and coexistence of two or more kinds of SRO, (ii stabilization of dense random packing structure by restraining the atomic redistribution for initiating the nucleation and growth process, (iii formation of a stable cluster (SC or the MRO by the harmonious coupling of SROs, and (iv difference between SRO characterizing the liquid structure and the near-neighbor environment in the corresponding equilibrium crystalline phases. The use of interaction parameters, widely used in the thermodynamics of multicomponent metallic solutions, is proposed for effectively selecting the third solute element (X3 for enhancing the GFA of a metallic liquid (M containing the second solute (X2. Fe70-B20-(X310 alloys (X3=Cr, W, Nb, Zr and Hf are used for illustration. Two typical model structures denoted by the Bernal and chemical-order types are used in describing the new glass structure as a function of solute concentration.

  20. Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) isolates of swine origin form robust biofilms

    Science.gov (United States)

    Methicillin-resistant Staphylococcus aureus (MRSA) colonization of livestock animals is common and prevalence rates for pigs have been reported to be as high as 49%. One hypothesis to explain the high prevalence of MRSA in swine herds is the ability of these organisms to exist as biofilms. To invest...

  1. Inhibitory effects of Tamarix hispida extracts on planktonic form and biofilm formation of six pathogenic bacteria

    OpenAIRE

    Zianab Mohsenipour; Mehdi Hassanshahian

    2015-01-01

     Introduction: Biofilms are communities of microorganisms embedded in a self-produced extracellular polymeric matrix. Bacterial cells are protected from antimicrobial agents in biofilm structure. Biofilms formation cause many problems in industry, medicine and microbial drug resistance; thus it is essential to find new techniques for removing and inhibiting biofilms. This study aimed to examine the antimicrobial effect of Tamarix hispida alcoholic extracts against six path...

  2. The effect of Streptococcus mutans and Candida glabrata on Candida albicans biofilms formed on different surfaces

    NARCIS (Netherlands)

    T. Pereira-Cenci; D.M. Deng; E.A. Kraneveld; E.M.M. Manders; A.A. Del Bel Cury; J.M. ten Cate; W. Crielaard

    2008-01-01

    Although Candida containing biofilms contribute to the development of oral candidosis, the characteristics of multi-species Candida biofilms and how oral bacteria modulate these biofilms is poorly understood. The aim of this study was to investigate interactions between Candida albicans and either C

  3. Atypical Enteropathogenic Escherichia coli Strains form Biofilm on Abiotic Surfaces Regardless of Their Adherence Pattern on Cultured Epithelial Cells

    Directory of Open Access Journals (Sweden)

    Hebert F. Culler

    2014-01-01

    Full Text Available The aim of this study was to determine the capacity of biofilm formation of atypical enteropathogenic Escherichia coli (aEPEC strains on abiotic and biotic surfaces. Ninety-one aEPEC strains, isolated from feces of children with diarrhea, were analyzed by the crystal violet (CV assay on an abiotic surface after 24 h of incubation. aEPEC strains representing each HEp-2 cell type of adherence were analyzed after 24 h and 6, 12, and 18 days of incubation at 37°C on abiotic and cell surfaces by CFU/cm2 counting and confocal laser scanning microscopy (CLSM. Biofilm formation on abiotic surfaces occurred in 55 (60.4% of the aEPEC strains. There was no significant difference in biofilm biomass formation on an abiotic versus prefixed cell surface. The biofilms could be visualized by CLSM at various developmental stages. aEPEC strains are able to form biofilm on an abiotic surface with no association with their adherence pattern on HEp-2 cells with the exception of the strains expressing UND (undetermined adherence. This study revealed the capacity of adhesion and biofilm formation by aEPEC strains on abiotic and biotic surfaces, possibly playing a role in pathogenesis, mainly in cases of persistent diarrhea.

  4. Histamine-producing Lactobacillus parabuchneri strains isolated from grated cheese can form biofilms on stainless steel.

    Science.gov (United States)

    Diaz, Maria; Del Rio, Beatriz; Sanchez-Llana, Esther; Ladero, Victor; Redruello, Begoña; Fernández, María; Martin, M Cruz; Alvarez, Miguel A

    2016-10-01

    The consumption of food containing large amounts of histamine can lead to histamine poisoning. Cheese is one of the most frequently involved foods. Histamine, one of the biogenic amines (BAs) exhibiting the highest safety risk, accumulates in food contaminated by microorganisms with histidine decarboxylase activity. The origin of these microorganisms may be very diverse with contamination likely occurring during post-ripening processing, but the microorganisms involved during this manufacturing step have never been identified. The present work reports the isolation of 21 histamine-producing Lactobacillus parabuchneri strains from a histamine-containing grated cheese. PCR revealed that every isolate carried the histidine decarboxylase gene (hdcA). Eight lineages were identified based on the results of genome PFGE restriction analysis plus endonuclease restriction profile analysis of the carried plasmids. Members of all lineages were able to form biofilms on polystyrene and stainless steel surfaces. L. parabuchneri is therefore an undesirable species in the dairy industry; the biofilms it can produce on food processing equipment represent a reservoir of histamine-producing bacteria and thus a source of contamination of post-ripening-processed cheeses. PMID:27375247

  5. Capillary isoelectric focusing--useful tool for detection of the biofilm formation in Staphylococcus epidermidis.

    Science.gov (United States)

    Ruzicka, Filip; Horka, Marie; Hola, Veronika; Votava, Miroslav

    2007-03-01

    The biofilm formation is an important factor of S. epidermidis virulence. Biofilm-positive strains might be clinically more important than biofilm-negative ones. Unlike biofilm-negative staphylococci, biofilm-positive staphylococci are surrounded with an extracellular polysaccharide substance. The presence of this substance on the surface can affect physico-chemical properties of the bacterial cell, including surface charge. 73 S. epidermidis strains were examined for the presence of ica operon, for the ability to form biofilm by Christensen test tube method and for the production of slime by Congo red agar method. Isoelectric points (pI) of these strains were determined by means of Capillary Isoelectric Focusing. The biofilm negative strains focused near pI value 2.3, while the pI values of the biofilm positive strains were near 2.6. Isoelectric point is a useful criterion for the differentiation between biofilm-positive and biofilm-negative S. epidermidis strains. PMID:17157942

  6. Extracellular DNA formation during biofilm development by freshwater bacteria

    DEFF Research Database (Denmark)

    Tang, Lone; Schramm, Andreas; Revsbech, Niels Peter;

    2011-01-01

    a transient peak at 6 hours, and in Rheinheimera the concentration peaked at 12 hours and remained high. Interestingly, the Rheinheimera biofilm dispersed immediately after the eDNA concentration peaked. The antimicrobial effect of eDNA was tested in growth experiments, and Rheinheimera was strongly......Extracellular DNA (eDNA) has been shown to be important for biofilm formation, both in the initial step of biofilm formation (attachment), and for securing the structural stability of the mature biofilm. It is unclear whether a general consensus exists for when in biofilm formation the presence of...... eDNA is most important. In this study, we investigated the significance of eDNA during biofilm formation in four freshwater isolates. The aim was to relate the quantity and timing of eDNA production to the isolates’ ability to form biofilms. eDNA and biofilm biomass was quantified over time during...

  7. Effect of peracetic acid on biofilms formed by Staphylococcus aureus and Listeria monocytogenes isolated from dairy plants.

    Science.gov (United States)

    Lee, S H I; Cappato, L P; Corassin, C H; Cruz, A G; Oliveira, C A F

    2016-03-01

    This research investigated the removal of adherent cells of 4 strains of Staphylococcus aureus and 1 Listeria monocytogenes strain (previously isolated from dairy plants) from polystyrene microtiter plates using peracetic acid (PAA, 0.5%) for 15, 30, 60, and 120 s, and the inactivation of biofilms formed by those strains on stainless steel coupons using the same treatment times. In the microtiter plates, PAA removed all S. aureus at 15 s compared with control (no PAA treatment). However, L. monocytogenes biofilm was not affected by any PAA treatment. On the stainless steel surface, epifluorescence microscopy using LIVE/DEAD staining (BacLight, Molecular Probes/Thermo Fisher Scientific, Eugene, OR) showed that all strains were damaged within 15 s, with almost 100% of cells inactivated after 30 s. Results of this trial indicate that, although PAA was able to inactivate both S. aureus and L. monocytogenes monospecies biofilms on stainless steel, it was only able to remove adherent cells of S. aureus from polystyrene microplates. The correct use of PAA is critical for eliminating biofilms formed by S. aureus strains found in dairy plants, although further studies are necessary to determine the optimal PAA treatment for removing biofilms of L. monocytogenes. PMID:26723125

  8. Bacterial biofilms. Bacteria Quorum sensing in biofilms

    OpenAIRE

    E. S. Vorobey; O. S. Voronkova; A. I. Vinnikov

    2012-01-01

    Data on biofilms, their structure and properties, peculiarities of formation and interaction between microorganisms in the film are presented. Information on discovery and study of biofilms, importance of biofilms in the medical and clinical microbiology are offered. The data allow to interpret biofilm as a form of existence of human normal microflora. For the exchange of information within the biofilm between the individual cells of the same or different species bacteria use the signal molec...

  9. Bacterial biofilms. Bacteria Quorum sensing in biofilms

    Directory of Open Access Journals (Sweden)

    E. S. Vorobey

    2012-03-01

    Full Text Available Data on biofilms, their structure and properties, peculiarities of formation and interaction between microorganisms in the film are presented. Information on discovery and study of biofilms, importance of biofilms in the medical and clinical microbiology are offered. The data allow to interpret biofilm as a form of existence of human normal microflora. For the exchange of information within the biofilm between the individual cells of the same or different species bacteria use the signal molecules of the Quorum sensing system. Coordination of bacterial cells activity in the biofilms gives them significant advantages: in the biofilms bacteria are protected from the influence of the host protective factors and the antibacterial drugs.

  10. Analysis of meticillin-susceptible and meticillin-resistant biofilm-forming Staphylococcus aureus from catheter infections isolated in a large Italian hospital.

    Science.gov (United States)

    Petrelli, Dezemona; Repetto, Antonella; D'Ercole, Stefania; Rombini, Silvia; Ripa, Sandro; Prenna, Manuela; Vitali, Luca Agostino

    2008-03-01

    Several characteristics were analysed in 37 Staphylococcus aureus isolates from nosocomial catheter infections: the PFGE profile after SmaI digestion of chromosomal DNA, the ability to form a biofilm on a polystyrene surface, antibiotic susceptibility patterns (penicillin, oxacillin, erythromycin, tetracycline, clindamycin, telithromycin, gentamicin, ciprofloxacin, quinupristin/dalfopristin, rifampicin, vancomycin and linezolid), and the presence of genetic determinants of antibiotic resistance and biofilm formation. All strains but three (92 %) were able to grow on a plastic surface as a biofilm. An almost complete association was found between phenotypes and genotypic traits of antibiotic resistance, whilst PFGE profiling showed the highly polyclonal composition of the set of strains under study. Sixteen isolates (43 %) were meticillin-resistant and were subjected to staphylococcal cassette chromosome mec (SCCmec) and cassette chromosome recombinase (ccr) complex type determination by multiplex PCR. Only a subgroup of six strains belonged to the archaic clone PFGE type and bore the SCCmec/ccrAB type I structure. Among the remaining strains some presented small rearrangements of the SCCmec/ccrAB genetic locus, whilst others could barely be traced back to a known structural type. These observations suggest that, at the local level and at a particular site of infection, S. aureus may show great genetic variability and escape the general rule of expansion of the S. aureus pandemic clones. PMID:18287301

  11. Bactericidal Compounds Controlling Growth of the Plant Pathogen Pseudomonas syringae pv. actinidiae, Which Forms Biofilms Composed of a Novel Exopolysaccharide

    Science.gov (United States)

    Ghods, Shirin; Sims, Ian M.; Moradali, M. Fata

    2015-01-01

    Pseudomonas syringae pv. actinidiae is the major cause of bacterial canker and is a severe threat to kiwifruit production worldwide. Many aspects of the disease caused by P. syringae pv. actinidiae, such as the pathogenicity-relevant formation of a biofilm composed of extracellular polymeric substances (EPSs), are still unknown. Here, a highly virulent strain of P. syringae pv. actinidiae, NZ V-13, was studied with respect to biofilm formation and architecture using a flow cell system combined with confocal laser scanning microscopy. The biofilm formed by P. syringae pv. actinidiae NZ V-13 was heterogeneous, consisting of a thin cellular base layer 5 μm thick and microcolonies with irregular structures. The major component of the EPSs produced by P. syringae pv. actinidiae NZ V-13 bacteria was isolated and identified to be an exopolysaccharide. Extensive compositional and structural analysis showed that rhamnose, fucose, and glucose were the major constituents, present at a ratio of 5:1.5:2. Experimental evidence that P. syringae pv. actinidiae NZ V-13 produces two polysaccharides, a branched α-d-rhamnan with side chains of terminal α-d-Fucf and an α-d-1,4-linked glucan, was obtained. The susceptibility of the cells in biofilms to kasugamycin and chlorine dioxide was assessed. About 64 and 73% of P. syringae pv. actinidiae NZ V-13 cells in biofilms were killed when kasugamycin and chlorine dioxide were used at 5 and 10 ppm, respectively. Kasugamycin inhibited the attachment of P. syringae pv. actinidiae NZ V-13 to solid surfaces at concentrations of 80 and 100 ppm. Kasugamycin was bacteriostatic against P. syringae pv. actinidiae NZ V-13 growth in the planktonic mode, with the MIC being 40 to 60 ppm and a bactericidal effect being found at 100 ppm. Here we studied the formation, architecture, and composition of P. syringae pv. actinidiae biofilms as well as used the biofilm as a model to assess the efficacies of bactericidal compounds. PMID:25841017

  12. Detection of bacteria bearing resistant biofilm forms, by using the universal and specific PCR is still unhelpful in the diagnosis of periprosthetic joint infections(PJI.

    Directory of Open Access Journals (Sweden)

    StylianosChatzipanagiotou

    2014-09-01

    Full Text Available Intraoperative conventional bacteriological cultures were compared with different polymerase chain reaction (PCR methods in patients with total joint arthroplasties. The isolated bacteria were investigated for biofilm formation, and the biofilm forming strains, in their planktonic and biofilm forms, were further tested for their antimicrobial resistance against several clinically important antimicrobials. Forty four bone and joint samples were included and classified as infected or non-infected according to standard criteria for periprosthetic hip and knee infections. For the bacteriological diagnosis, conventional culture, two types of universal PCR and species specific PCR for three selected pathogens (S. aureus, S. epidermidis, P. aeruginosa were applied. Biofilm formation determination was performed by the tissue culture plate method. Antimicrobial susceptibility of the planktonic bacteria was performed by the minimal inhibitory concentration determination and, of the biofilm forms, by the minimal inhibitory concentration for bacterial regrowth from the biofilm. Twenty samples were culture positive, with S. epidermidis, S. aureus or P. aeruginosa. All PCR methods were very ineffective in detecting only one pathogen. All isolates were biofilm positive and their biofilm forms, were highly resistant. In this study, compared to PCR, culture remains the “gold standard”. The biofilm formation by the causative bacteria and the concomitant manifold increased antimicrobial resistance may explain the clinical failure of treatment in some cases and should be considered in the future for therapeutic planning.

  13. Long-term succession of structure and diversity of a biofilm formed in a model drinking water distribution system

    DEFF Research Database (Denmark)

    Martiny, A.C.; Jørgensen, T.M.; Albrechtsen, Hans-Jørgen;

    2003-01-01

    In this study, we examined the long-term development of the overall structural morphology and community composition of a biofilm formed in a model drinking water distribution system with biofilms from 1 day to 3 years old. Visualization and subsequent quantification showed how the biofilm developed...... from an initial attachment of single cells through the formation of independent microcolonies reaching 30 mum in thickness to a final looser structure with an average thickness of 14.1 mum and covering 76% of the surface. An analysis of the community composition by use of terminal restriction fragment...... of 16S rRNA fragments illustrated how a wide variety of cells recruited from the bulk water initially attached and resulted in a species richness comparable to that in the water phase. This step was followed by the growth of a bacterium which was related to Nitrospira, which constituted 78% of the...

  14. Electrical spiking in bacterial biofilms

    OpenAIRE

    Masi, Elisa; Ciszak, Marzena; Santopolo, Luisa; Frascella, Arcangela; Giovannetti, Luciana; Marchi, Emmanuela; Viti, Carlo; Mancuso, Stefano

    2015-01-01

    In nature, biofilms are the most common form of bacterial growth. In biofilms, bacteria display coordinated behaviour to perform specific functions. Here, we investigated electrical signalling as a possible driver in biofilm sociobiology. Using a multi-electrode array system that enables high spatio-temporal resolution, we studied the electrical activity in two biofilm-forming strains and one non-biofilm-forming strain. The action potential rates monitored during biofilm-forming bacterial gro...

  15. Ability of chitosan gels to disrupt bacterial biofilms and their applications in the treatment of bacterial vaginosis.

    Science.gov (United States)

    Kandimalla, Karunya K; Borden, Emma; Omtri, Rajesh S; Boyapati, Siva Prasad; Smith, Michael; Lebby, Kimberly; Mulpuru, Maanavi; Gadde, Mounika

    2013-07-01

    Recurrence of bacterial vaginosis is attributed to the inability of various formulations to disrupt bacterial biofilms. A negatively charged polysaccharide matrix coats the bacterial communities in the biofilm and restricts the penetration of antibiotics. Therefore, bacteria in the deeper segments of the biofilm persist and perpetuate the infection. In this study, we have tested the efficacy of two bioadhesive polymers, cationic chitosan and anionic polycarbophil, to disrupt Pseudomonas aeruginosa biofilms grown in the Center for Disease Control bioreactor as well as on the 96-well plates. The biofilms were treated with various concentrations of polycarbophil and chitosan at pH 4 or 6. Biofilm integrity following various treatments was evaluated by crystal violet stain and laser confocal microscopy employing Syto9 (live-cell stain) and propidium iodide (dead-cell stain). These studies demonstrated that chitosan gel disrupts the P. aeruginosa biofilm more effectively than does polycarbophil; and this effect is independent of the pH and charge densities on either polymers. PMID:23695992

  16. The Composition and Metabolic Phenotype of Neisseria gonorrhoeae Biofilms

    Directory of Open Access Journals (Sweden)

    Michael A Apicella

    2011-04-01

    Full Text Available N. gonorrhoeae has been shown to form biofilms during cervical infection. Thus, biofilm formation may play an important role in the infection of women. The ability of N. gonorrhoeae to form membrane blebs is crucial to biofilm formation. Blebs contain DNA and outer membrane structures, which have been shown to be major constituents of the biofilm matrix. The organism expresses a DNA thermonuclease that is involved in remodeling of the biofilm matrix. Comparison of the transcriptional profiles of gonococcal biofilms and planktonic runoff indicate that genes involved in anaerobic metabolism and oxidative stress tolerance are more highly expressed in biofilm. The expression of aniA, ccp, and norB, which encode nitrite reductase, cytochrome c peroxidase, and nitric oxide reductase respectively, is required for mature biofilm formation over glass and human cervical cells. In addition, anaerobic respiration occurs in the substratum of gonococcal biofilms and disruption of the norB gene required for anaerobic respiration, results in a severe biofilm attenuation phenotype. It has been demonstrated that accumulation of nitric oxide (NO contributes to the phenotype of a norB mutant and can retard biofilm formation. However, NO can also enhance biofilm formation, and this is largely dependent on the concentration and donation rate or steady state kinetics of NO. The majority of the genes involved in gonococcal oxidative stress tolerance are also required for normal biofilm formation, as mutations in the following genes result in attenuated biofilm formation over cervical cells and/or glass: oxyR, gor, prx, mntABC, trxB, and estD. Overall, biofilm formation appears to be an adaptation for coping with the environmental stresses present in the female genitourinary tract. Therefore, this review will discuss the studies, which describe the composition and metabolic phenotype of gonococcal biofilms.

  17. Biofilm forming cyanobacteria, algae and fungi on two historic monuments in Belgrade, Serbia

    Directory of Open Access Journals (Sweden)

    Ljaljević-Grbić Milica

    2010-01-01

    Full Text Available Biofilm on the sandstone substrata of the bridge 'Brankov most' and on the granite substrata of the 'Monument of the Unknown Hero' contains a complex consortia of cyanobacteria, algae, and fungi. Coccoid and filamentous cyanobacteria, green algae and diatoms make up the photosynthetic part of the biofilm while hyphal fragments, chlamydospores, fruiting bodies and spores take part as fungal components. These structures make a dense layer by intertwining and overlapping the stone surface. Five cyanobacterial, 11 algal and 23 fungal taxa were found. The interaction of the biofilm's constituents results in the bioweathering of the stone substrata through mechanical penetration, acid corrosion and the production of secondary mycogenic biominerals. .

  18. Career Adapt-Abilities Scale--Netherlands Form: Psychometric Properties and Relationships to Ability, Personality, and Regulatory Focus

    Science.gov (United States)

    van Vianen, Annelies E. M.; Klehe, Ute-Christine; Koen, Jessie; Dries, Nicky

    2012-01-01

    The Career Adapt-Abilities Scale (CAAS)--Netherlands Form consists of four scales, each with six items, which measure concern, control, curiosity, and confidence as psychosocial resources for managing occupational transitions, developmental tasks, and work traumas. Internal consistency estimates for the subscale and total scores ranged from…

  19. Molecular Studies of Filamentous and Biofilm-Forming Hyperthermophilic Communities in Yellowstone National Park

    Science.gov (United States)

    Summons, R. E.; Meyer-Dombard, D. R.; Bradley, A. S.; Dibbell, A. K.; Fredricks, H. F.; Hinrichs, K.; Jahnke, L. L.; Shock, E.; Amend, J. P.

    2005-12-01

    The Aquificales, the most deeply-branching order of Bacteria in the phylogenetic tree of life, comprises eight recognized thermophilic genera, including Aquifex, Hydrogenobacter, and Thermocrinis. The common metabolism for these Bacteria, when grown in culture, is the oxidation of hydrogen with molecular oxygen (Knallgas reaction). Aquificales have been identified by molecular techniques (16S rRNA gene surveys, fluorescent in situ hybridization) in Yellowstone National Park (YNP), sea vent chimneys and fluids, and many other terrestrial and marine locations. In situ, Aquificales can reside as biofilms on vent sinters but they also commonly form filamentous communities, otherwise known as pink streamers, which attach to solid substrates. Initial 16S rRNA gene surveys conducted on streamer communities from Octopus Spring YNP indicated that these were low diversity ecosystems dominated by a few phylotypes including Thermocrinis sp., Thermotoga sp. and one other bacterial clade (Reysenbach et al 1994). Archaea were notable for their absence. In one of the first geobiological studies of pink streamers and vent biofilms in Yellowstone National Park, Jahnke and coworkers (2001) used classical lipidological techniques to compare Aquificales cultures with environmental samples to show that YNP pink filaments were more phylogenetically diverse and physiologically more complex than the early genomic studies indicated. The presence of archaeol, the range and structures of other lipids and a wide dispersion in the carbon isotopic signatures of biomass and individual lipids (-15 to -27%) showed that Archaea were present in pink filament communities and that there was, at least, one additional bacterial group besides the dominant Aquificales component. New molecular studies that comprise analyses of 16S rRNA genes and total lipid extracts by liquid chromatography and mass spectrometry and chemical degradation with gas chromatography and mass spectrometry now show that Crenarchaea

  20. In vitro antimicrobial activity of mouth washes and herbal products against dental biofilm-forming bacteria

    Directory of Open Access Journals (Sweden)

    Naiana B Da Silva

    2012-01-01

    Full Text Available Aim: To evaluate in vitro, the antimicrobial effect of Cymbopogon citrates (lemon grass, Plectranthusamboinicus (Mexican mint and Conyzabonariensis (hairy fleabane tinctures as well as pure and diluted commercial mouth washes (Malvatricin® , Periogard® and Listerine® on wild isolates of Streptococcusmutans and reference strains of S. mutans, Streptococcus salivarius, Streptococcus oralis and Lactobacillus casei by determination of minimum inhibitory dilution (MID. Materials and Methods: 0.12% chlorhexidine and 70% corn alcohol were used as positive and negative controls, respectively. Saliva samples were collected from 3 volunteers and seeded in MSB broth to obtain Streptococcus isolates after 72-hour incubation. Using the agar diffusion method, susceptibility tests were performed with overnight incubation in microaerophilia at 37°C. All tests were performed in duplicate. Results: The bacterial species were resistant to the tinctures and Listerine® , but were susceptible to 0.12% chlorhexidine, Malvatricin® and Periogard® , with MIDs ranging from 12.5% to 1.56%. Conclusions: Plectrantusamboinicus, Conyzabonariensis and Cymbopongoncitratus tinctures and Listerine® did not show inhibitory action against the tested biofilm-forming bacteria.

  1. Bioactive glass combined with bisphosphonates provides protection against biofilms formed by the periodontal pathogen Aggregatibacter actinomycetemcomitans.

    Science.gov (United States)

    Hiltunen, Anna K; Skogman, Malena E; Rosenqvist, Kirsi; Juvonen, Helka; Ihalainen, Petri; Peltonen, Jouko; Juppo, Anne; Fallarero, Adyary

    2016-03-30

    Biofilms play a pivotal role in the progression of periodontitis and they can be treated with antiseptics (i.e. chlorhexidine) or antibiotics, but these therapeutic alternatives are unable of ameliorating periodontal alveolar bone loss, which has been, on the other hand, successfully treated with bone-preserving agents. The improved bone formation achieved in animal models by the combination of two such agents: bioactive glass (BAG) and bisphosphonates has attracted the interest for further exploring dental applications. However, the antimicrobial effects that may result from combining them have not been yet investigated. Here, our aim was to explore the anti-biofilm effects that could result from combining BAG with bisphosphonates, particularly in a dental biofilm model. The experiments were performed with an oral cavity single-specie (Aggregatibacter actinomycetemcomitans) biofilm assay, which was optimized in this contribution. Risedronate displayed an intrinsic anti-biofilm effect, and all bisphosphonates, except clodronate, reduced biofilm formation when combined with BAG. In particular, the anti-biofilm activity of risedronate was significantly increased by the combination with BAG. Since it has been proposed that some of the antimicrobial effects of BAG are caused by local pH changes, studies of pH variations were performed to gain a mechanistic understanding. However, the observed anti-biofilm effects could not be explained with lowered pHs. Overall, these results do provide further support for the promising use of bisphosphonate-BAG combinations in dental applications. These findings are particularly relevant for patients undergoing cancer chemotherapy, or osteoporotic patients, which are known to be more vulnerable to periodontitis. In such cases, bisphosphonate treatment could play a double positive effect: local treatment of periodontitis (in combination with BAG) and systemic treatment of osteoporosis, prevention of hypercalcemia and metastases. PMID

  2. Pseudomonas aeruginosa and Saccharomyces cerevisiae Biofilm in Flow Cells

    DEFF Research Database (Denmark)

    Weiss Nielsen, Martin; Sternberg, Claus; Molin, Søren;

    2011-01-01

    Many microbial cells have the ability to form sessile microbial communities defined as biofilms that have altered physiological and pathological properties compared to free living microorganisms. Biofilms in nature are often difficult to investigate and reside under poorly defined conditions(1). ...

  3. Biofilm formation by Staphylococcus aureus isolates from skin and soft tissue infections.

    Science.gov (United States)

    Kwiecinski, Jakub; Kahlmeter, Gunnar; Jin, Tao

    2015-05-01

    Many diseases caused by Staphylococcus aureus are associated with biofilm formation. However, the ability of S. aureus isolates from skin and soft tissue infections to form biofilms has not yet been investigated. We tested 160 isolates from patients with various skin infections for biofilm-forming capacity in different growth media. All the isolates formed biofilms, the extent of which depended on the type of growth medium. The thickest biofilms were formed when both plasma and glucose were present in the broth; in this case, S. aureus incorporated host fibrin into the biofilm's matrix. There were no differences in the biofilm formation between isolates from different types of skin infections, except for a particularly good biofilm formation by isolates from diabetic wounds and a weaker biofilm formation by isolates from impetigo. In conclusion, biofilm formation is a universal behavior of S. aureus isolates from skin infections. In some cases, such as in diabetic wounds, a particularly strong biofilm formation most likely contributes to the chronic and recurrent character of the infection. Additionally, as S. aureus apparently uses host fibrin as part of the biofilm structure, we suggest that plasma should be included more frequently in in vitro biofilm studies. PMID:25586078

  4. Nasopharyngeal and Adenoid Colonization by Haemophilus influenzae and Haemophilus parainfluenzae in Children Undergoing Adenoidectomy and the Ability of Bacterial Isolates to Biofilm Production.

    Science.gov (United States)

    Kosikowska, Urszula; Korona-Głowniak, Izabela; Niedzielski, Artur; Malm, Anna

    2015-05-01

    Haemophili are pathogenic or opportunistic bacteria often colonizing the upper respiratory tract mucosa. The prevalence of Haemophilus influenzae (with serotypes distribution), and H. parainfluenzae in the nasopharynx and/or the adenoid core in children with recurrent pharyngotonsillitis undergoing adenoidectomy was assessed. Haemophili isolates were investigated for their ability to biofilm production.Nasopharyngeal swabs and the adenoid core were collected from 164 children who underwent adenoidectomy (2-5 years old). Bacteria were identified by the standard methods. Serotyping of H. influenzae was performed using polyclonal and monoclonal antisera. Biofilm formation was detected spectrophotometrically using 96-well microplates and 0.1% crystal violet.Ninety seven percent (159/164) children who underwent adenoidectomy were colonized by Haemophilus spp. The adenoid core was colonized in 99.4% (158/159) children, whereas the nasopharynx in 47.2% (75/159) children (P parainfluenzae and 14 isolates of other Haemophilus spp. were selected. In 20.1% (32/159) children 2 or 3 phenotypically different isolates of the same species (H. influenzae or H. parainfluenzae) or serotypes (H. influenzae) were identified in 1 child. 67.2% (129/192) isolates of H. influenzae, 56.3% (54/96) isolates of H. parainfluenzae and 85.7% (12/14) isolates of other Haemophilus spp. were positive for biofilm production. Statistically significant differences (P = 0.0029) among H. parainfluenzae biofilm producers and nonproducers in the adenoid core and the nasopharynx were detected.H. influenzae and H. parainfluenzae carriage rate was comparatively higher in the adenoid core than that in the nasopharynx in children undergoing adenoidectomy, suggesting that their involvement in chronic adenoiditis. The growth in the biofilm seems to be an important feature of haemophili colonizing the upper respiratory tract responsible for their persistence. PMID:25950686

  5. Extracellular DNA is essential for maintaining Bordetella biofilm integrity on abiotic surfaces and in the upper respiratory tract of mice.

    Directory of Open Access Journals (Sweden)

    Matt S Conover

    Full Text Available Bacteria form complex and highly elaborate surface adherent communities known as biofilms which are held together by a self-produced extracellular matrix. We have previously shown that by adopting a biofilm mode of existence in vivo, the gram negative bacterial pathogens Bordetella bronchiseptica and Bordetella pertussis are able to efficiently colonize and persist in the mammalian respiratory tract. In general, the bacterial biofilm matrix includes polysaccharides, proteins and extracellular DNA (eDNA. In this report, we investigated the function of DNA in Bordetella biofilm development. We show that DNA is a significant component of Bordetella biofilm matrix. Addition of DNase I at the initiation of biofilm growth inhibited biofilm formation. Treatment of pre-established mature biofilms formed under both static and flow conditions with DNase I led to a disruption of the biofilm biomass. We next investigated whether eDNA played a role in biofilms formed in the mouse respiratory tract. DNase I treatment of nasal biofilms caused considerable dissolution of the biofilm biomass. In conclusion, these results suggest that eDNA is a crucial structural matrix component of both in vitro and in vivo formed Bordetella biofilms. This is the first evidence for the ability of DNase I to disrupt bacterial biofilms formed on host organs.

  6. The Biofilm Challenge

    DEFF Research Database (Denmark)

    Alhede, Maria; Alhede, Morten

    2014-01-01

    The concept of biofilms has emerged in the clinical setting during the last decade. Infections involving biofilms have been documented in all parts of the human body, and it is currently believed that the presence of biofilm-forming bacteria is equivalent to chronic infection. A quick Pubmed search...... reveals the significance of biofilms, as evidenced by a dramatic increase in scientific publications on the topic, as well as in publications concerning wounds with biofilms, which reached 600 publications in 2013. Judged from the number of publications, it appears that biofilms play a significant role in...... wounds. However, the impact of biofilms is often debated, because infected wounds were also treated before the concept of biofilms was coined. In this short review, we will address the significance of biofilms and their role in wounds, and discuss the future tasks of the biofilm challenge....

  7. Screening of Compounds against Gardnerella vaginalis Biofilms.

    Directory of Open Access Journals (Sweden)

    Cornelia Gottschick

    Full Text Available Bacterial vaginosis (BV is a common infection in reproductive age woman and is characterized by dysbiosis of the healthy vaginal flora which is dominated by Lactobacilli, followed by growth of bacteria like Gardnerella vaginalis. The ability of G. vaginalis to form biofilms contributes to the high rates of recurrence that are typical for BV and which unfortunately make repeated antibiotic therapy inevitable. Here we developed a biofilm model for G. vaginalis and screened a large spectrum of compounds for their ability to prevent biofilm formation and to resolve an existing G. vaginalis biofilm. The antibiotics metronidazole and tobramycin were highly effective in preventing biofilm formation, but had no effect on an established biofilm. The application of the amphoteric tenside sodium cocoamphoacetate (SCAA led to disintegration of existing biofilms, reducing biomass by 51% and viability by 61% and it was able to increase the effect of metronidazole by 40% (biomass and 61% (viability. Our data show that attacking the biofilm and the bacterial cells by the combination of an amphoteric tenside with the antibiotic metronidazole might be a useful strategy against BV.

  8. Screening of Compounds against Gardnerella vaginalis Biofilms.

    Science.gov (United States)

    Gottschick, Cornelia; Szafranski, Szymon P; Kunze, Brigitte; Sztajer, Helena; Masur, Clarissa; Abels, Christoph; Wagner-Döbler, Irene

    2016-01-01

    Bacterial vaginosis (BV) is a common infection in reproductive age woman and is characterized by dysbiosis of the healthy vaginal flora which is dominated by Lactobacilli, followed by growth of bacteria like Gardnerella vaginalis. The ability of G. vaginalis to form biofilms contributes to the high rates of recurrence that are typical for BV and which unfortunately make repeated antibiotic therapy inevitable. Here we developed a biofilm model for G. vaginalis and screened a large spectrum of compounds for their ability to prevent biofilm formation and to resolve an existing G. vaginalis biofilm. The antibiotics metronidazole and tobramycin were highly effective in preventing biofilm formation, but had no effect on an established biofilm. The application of the amphoteric tenside sodium cocoamphoacetate (SCAA) led to disintegration of existing biofilms, reducing biomass by 51% and viability by 61% and it was able to increase the effect of metronidazole by 40% (biomass) and 61% (viability). Our data show that attacking the biofilm and the bacterial cells by the combination of an amphoteric tenside with the antibiotic metronidazole might be a useful strategy against BV. PMID:27111438

  9. Screening of Compounds against Gardnerella vaginalis Biofilms

    Science.gov (United States)

    Gottschick, Cornelia; Szafranski, Szymon P.; Kunze, Brigitte; Sztajer, Helena; Masur, Clarissa; Abels, Christoph; Wagner-Döbler, Irene

    2016-01-01

    Bacterial vaginosis (BV) is a common infection in reproductive age woman and is characterized by dysbiosis of the healthy vaginal flora which is dominated by Lactobacilli, followed by growth of bacteria like Gardnerella vaginalis. The ability of G. vaginalis to form biofilms contributes to the high rates of recurrence that are typical for BV and which unfortunately make repeated antibiotic therapy inevitable. Here we developed a biofilm model for G. vaginalis and screened a large spectrum of compounds for their ability to prevent biofilm formation and to resolve an existing G. vaginalis biofilm. The antibiotics metronidazole and tobramycin were highly effective in preventing biofilm formation, but had no effect on an established biofilm. The application of the amphoteric tenside sodium cocoamphoacetate (SCAA) led to disintegration of existing biofilms, reducing biomass by 51% and viability by 61% and it was able to increase the effect of metronidazole by 40% (biomass) and 61% (viability). Our data show that attacking the biofilm and the bacterial cells by the combination of an amphoteric tenside with the antibiotic metronidazole might be a useful strategy against BV. PMID:27111438

  10. 乳酸菌在不同食品包装材料生物膜形成特性%Spectrophotometer and scanning electron microscopy study of lactic acid bacteria biofilm forming on different materials

    Institute of Scientific and Technical Information of China (English)

    黄宝威; 许佳晶; 刘彦兰; 郑添信; 吴金玉; 谢丽斯; 张宏梅

    2012-01-01

    Objective: To study the lactic acid bacteria forming on different materials. Methods, Plastics Packaging Materials(HDPE) ,aluminum composite inner carton packaging,composite metal materials and glass were added into liquid mediums respectively. Strains grow at the same temperature and time for 6d.Spectrophotometer and scanning electron microscopy were used for testing the biofilm formation. Results. Lactic acid bacteria had weak biofilm formation ability.Strains showed the best biofilm formation ability on composite plastic packaging materials (HDPE)than on the other materials.The second level biofilm formation ability was on the glass, and the most difficult biofilm formation was on the aluminum composite metal. Similar result could be observed by scanning electron microscopy. Conclusion. The lactic acid bacteria biofilm could form easier on the plastic packaging material than on the other materials,the most difficult bacteria biofilm formation was on metal.%目的:研究乳酸茵在不同材料成膜情况。方法:用液体培养基在同一温度、时间,分别加入复合塑料包装材料(HDPE)、纸盒包装内层的复合铝膜、复合金属铝包装材料、玻璃4种不同包装材料上进行培养,6d后分别用分光光度计法和扫描电镜法检测成膜情况。结果:实验菌株乳酸菌有相对较弱的戚膜能力:用分光光度法测得复合塑料包装材料(HDPE)上的茵膜吸光度相对较大,玻璃次之,复合金属铝包装材料数值最小;通过扫描电镜观察得出相似结果。结论:乳酸茵在复合塑料包装材料上成膜最好;在金属铝上成膜最差。

  11. Evaluation of antimicrobial efficacy of Triphala (an Indian Ayurvedic herbal formulation and 0.2% chlorhexidine against Streptococcus mutans biofilm formed on tooth substrate: An in vitro study

    Directory of Open Access Journals (Sweden)

    J Prabhakar

    2014-01-01

    Conclusion: Triphala showed statistically significant antibacterial activity against S. mutans biofilm formed on tooth substrate. The incorporation of Triphala in mouth rinse could prove to be effective in reducing S. mutans count in the oral cavity.

  12. Effectiveness of Chitosan against Mature Biofilms Formed by Food Related Bacteria

    Directory of Open Access Journals (Sweden)

    Carmen San Jose

    2011-01-01

    Full Text Available Chitosan has proven antimicrobial properties against planktonic cell growth. Little is known, however, about its effects on already established biofilms. Oriented for application in food industry disinfection, the effectiveness of both medium molecular weight (MMW chitosan and its enzymatically hydrolyzed product was tested against mature biofilms of four pathogenic strains, Listeria monocytogenes, Bacillus cereus, Staphylococcus aureus and Salmonella enterica, and a food spoilage species, Pseudomonas fluorescens. Unexpectedly, log reductions were in some cases higher for biofilm than for planktonic cells. One hour exposure to MMW chitosan (1% w/v caused a 6 log viable cell reduction on L. monocytogenes monospecies mature biofilms and reduced significantly (3–5 log reductions the attached population of the other organisms tested, except S. aureus. Pronase-treated chitosan was more effective than MMW chitosan on all tested microorganisms, also with the exception of S. aureus, offering best results (8 log units against the attached cells of B. cereus. These treatments open a new possibility to fight against mature biofilms in the food industry.

  13. Prophage spontaneous activation promotes DNA release enhancing biofilm formation in Streptococcus pneumoniae.

    Directory of Open Access Journals (Sweden)

    Margarida Carrolo

    Full Text Available Streptococcus pneumoniae (pneumococcus is able to form biofilms in vivo and previous studies propose that pneumococcal biofilms play a relevant role both in colonization and infection. Additionally, pneumococci recovered from human infections are characterized by a high prevalence of lysogenic bacteriophages (phages residing quiescently in their host chromosome. We investigated a possible link between lysogeny and biofilm formation. Considering that extracellular DNA (eDNA is a key factor in the biofilm matrix, we reasoned that prophage spontaneous activation with the consequent bacterial host lysis could provide a source of eDNA, enhancing pneumococcal biofilm development. Monitoring biofilm growth of lysogenic and non-lysogenic pneumococcal strains indicated that phage-infected bacteria are more proficient at forming biofilms, that is their biofilms are characterized by a higher biomass and cell viability. The presence of phage particles throughout the lysogenic strains biofilm development implicated prophage spontaneous induction in this effect. Analysis of lysogens deficient for phage lysin and the bacterial major autolysin revealed that the absence of either lytic activity impaired biofilm development and the addition of DNA restored the ability of mutant strains to form robust biofilms. These findings establish that limited phage-mediated host lysis of a fraction of the bacterial population, due to spontaneous phage induction, constitutes an important source of eDNA for the S. pneumoniae biofilm matrix and that this localized release of eDNA favors biofilm formation by the remaining bacterial population.

  14. Activity of ciprofloxacin and azithromycin on biofilms produced in vitro by Haemophilus influenzae

    Institute of Scientific and Technical Information of China (English)

    WANG Dong; WANG Ying; LIU You-ning

    2009-01-01

    Background It is recognized that Haemophilus influenzae isolated from patients with otitis media forms biofilms both in vitro and in vivo, suggesting that biofilm formation in vivo might play an important role in the pathogenesis and chronicity of otitis media, but the effect of antibiotics on biofilm has not been well studied. We investigated the impact of ciprofloxacin and azithromycin on bacterial biofilms formed by Haemophilus influenzae in vitro in this study.Methods Eleven strains of Haemophilus influenzae were isolated from sputum specimens collected from patients with acute exacerbation of chronic obstructive pulmonary diseases. Formation of bacterial biofilm was examined by crystal violet assay and a scanning electron microscope. Alterations of biofilms were measured under varying concentrations of azithromycin and ciprofloxacin.Results Striking differences were observed among strains with regard to the ability to form biofilm. Typical membrane-like structure formed by bacterial cells and extracellular matrix was detected. Initial biofilm synthesis was inhibited by azithromycin and ciprofloxacin at concentrations higher than two-fold minimal inhibitory concentration.Disruption of mature biofilms could be achieved at relatively higher concentration, and ciprofloxacin displayed more powerful activity.Conclusions Haemophilus influenzae is capable of forming biofilm in vitro. Sufficient dosage might control early formation of biofilms. Ciprofloxacin exerts better effects on breakdown of biofilm than azithromycin at conventional concentration in clinics.

  15. Investigations of Biofilm-Forming Bacterial Cells by Atomic Force Microscopy Prior to and Following Treatment from Gas Discharge Plasmas

    Science.gov (United States)

    Vandervoort, K. G.; Joaquin, J. C.; Kwan, C.; Bray, J. D.; Torrico, R.; Abramzon, N.; Brelles-Marino, G.

    2007-03-01

    We present investigations of biofilm-forming bacteria before and after treatment from gas discharge plasmas. Gas discharge plasmas represent a way to inactivate bacteria under conditions where conventional disinfection methods are often ineffective. These conditions involve bacteria in biofilm communities, where cooperative interactions between cells make organisms less susceptible to standard killing methods. Rhizobium gallicum and Chromobacterium violaceum were imaged before and after plasma treatment using an atomic force microscope (AFM). In addition, cell wall elasticity was studied by measuring force distance curves as the AFM tip was pressed into the cell surface. Results for cell surface morphology and micromechanical properties for plasma treatments lasting from 5 to 60 minutes were obtained and will be presented.

  16. Screening of Compounds against Gardnerella vaginalis Biofilms.

    OpenAIRE

    Gottschick, Cornelia; Szymon P Szafranski; Kunze, Brigitte; Sztajer, Helena; Masur, Clarissa; Abels, Christoph; Wagner-Döbler, Irene

    2016-01-01

    Bacterial vaginosis (BV) is a common infection in reproductive age woman and is characterized by dysbiosis of the healthy vaginal flora which is dominated by Lactobacilli, followed by growth of bacteria like Gardnerella vaginalis. The ability of G. vaginalis to form biofilms contributes to the high rates of recurrence that are typical for BV and which unfortunately make repeated antibiotic therapy inevitable. Here we developed a biofilm model for G. vaginalis and screened a large spectrum of ...

  17. Screening of Compounds against Gardnerella vaginalis Biofilms

    OpenAIRE

    Gottschick, Cornelia; Szymon P Szafranski; Kunze, Brigitte; Sztajer, Helena; Masur, Clarissa; Abels, Christoph; Wagner-Döbler, Irene

    2016-01-01

    Bacterial vaginosis (BV) is a common infection in reproductive age woman and is characterized by dysbiosis of the healthy vaginal flora which is dominated by Lactobacilli, followed by growth of bacteria like Gardnerella vaginalis. The ability of G. vaginalis to form biofilms contributes to the high rates of recurrence that are typical for BV and which unfortunately make repeated antibiotic therapy inevitable. Here we developed a biofilm model for G. vaginalis and screened a large spectrum of ...

  18. The Antistaphylococcal Activity of Citropin 1.1 and Temporin A against Planktonic Cells and Biofilms Formed by Isolates from Patients with Atopic Dermatitis: An Assessment of Their Potential to Induce Microbial Resistance Compared to Conventional Antimicrobials

    Directory of Open Access Journals (Sweden)

    Malgorzata Dawgul

    2016-05-01

    Full Text Available Staphylococcus aureus (SA colonizes the vast majority of patients with atopic dermatitis (AD. Its resistance to antibiotics and ability to form biofilms are the main origins of therapeutic complications. Endogenous antimicrobial peptides (AMPs exhibit strong activity against SA, including antibiotic resistant strains as well as bacteria existing in biofilm form. The purpose of the present work was to determine the antistaphylococcal activity of two amphibian peptides against SA isolated from patients with AD. The AMPs demonstrated permanent activity towards strains exposed to sublethal concentrations of the compounds and significantly stronger antibiofilm activity in comparison to that of conventional antimicrobials. The results suggest the potential application of amphibian AMPs as promising antistaphylococcal agents for the management of skin infections.

  19. Heterogeneity of biofilms formed by nonmucoid Pseudomonas aeruginosa isolates from patients with cystic fibrosis

    DEFF Research Database (Denmark)

    Lee, Baoleri; Haagensen, Janus Anders Juul; Ciofu, O.; Andersen, Jens Bo; Hoiby, N.; Molin, Søren

    2005-01-01

    Biofilms are thought to play a key role in the occurrence of lung infections by Pseudomonas aeruginosa in patients with cystic fibrosis (CF). In this study, 20 nonmucoid P. aeruginosa isolates collected during different periods of chronic infection from eight CF patients were assessed with respect...

  20. Microbial Diversity in the Early In Vivo-Formed Dental Biofilm.

    Science.gov (United States)

    Heller, D; Helmerhorst, E J; Gower, A C; Siqueira, W L; Paster, B J; Oppenheim, F G

    2016-03-01

    Although the mature dental biofilm composition is well studied, there is very little information on the earliest phase of in vivo tooth colonization. Progress in dental biofilm collection methodologies and techniques of large-scale microbial identification have made new studies in this field of oral biology feasible. The aim of this study was to characterize the temporal changes and diversity of the cultivable and noncultivable microbes in the early dental biofilm. Samples of early dental biofilm were collected from 11 healthy subjects at 0, 2, 4, and 6 h after removal of plaque and pellicle from tooth surfaces. With the semiquantitative Human Oral Microbiome Identification Microarray (HOMIM) technique, which is based on 16S rRNA sequence hybridizations, plaque samples were analyzed with the currently available 407 HOMIM microbial probes. This led to the identification of at least 92 species, with streptococci being the most abundant bacteria across all time points in all subjects. High-frequency detection was also made with Haemophilus parainfluenzae, Gemella haemolysans, Slackia exigua, and Rothia species. Abundance changes over time were noted for Streptococcus anginosus and Streptococcus intermedius (P = 0.02), Streptococcus mitis bv. 2 (P = 0.0002), Streptococcus oralis (P = 0.0002), Streptococcus cluster I (P = 0.003), G. haemolysans (P = 0.0005), and Stenotrophomonas maltophilia (P = 0.02). Among the currently uncultivable microbiota, eight phylotypes were detected in the early stages of biofilm formation, one belonging to the candidate bacterial division TM7, which has attracted attention due to its potential association with periodontal disease. PMID:26746720

  1. Early Staphylococcal Biofilm Formation on Solid Orthopaedic Implant Materials: In Vitro Study

    OpenAIRE

    Koseki, Hironobu; Yonekura, Akihiko; Shida, Takayuki; Yoda, Itaru; Horiuchi, Hidehiko; Morinaga, Yoshitomo; Yanagihara, Katsunori; Sakoda, Hideyuki; Osaki, Makoto; Tomita, Masato

    2014-01-01

    Biofilms forming on the surface of biomaterials can cause intractable implant-related infections. Bacterial adherence and early biofilm formation are influenced by the type of biomaterial used and the physical characteristics of implant surface. In this in vitro research, we evaluated the ability of Staphylococcus epidermidis, the main pathogen in implant-related infections, to form biofilms on the surface of the solid orthopaedic biomaterials, oxidized zirconium-niobium alloy, cobalt-chromiu...

  2. Frequency of biofilm formation in toothbrushes and wash basin junks

    Directory of Open Access Journals (Sweden)

    Abdulazeez A Abubakar

    2013-01-01

    Full Text Available Background: Biofilms are known to be resistant to several antibiotics once they are allowed to form on any surface. Aim: To investigate the biofilm forming ability of some bacterial isolates in toothbrushes and wash basin junks. Materials and Methods: A total of 606 students of Federal University of Technology, Yola were provided with new toothbrushes, which were collected after 1 month of usage and screened for biofilm formation. Another 620 swabs were collected from the wash basins of Federal Medical Centre, Specialist Hospital, Federal University of Technology, and students′ hostels in Yola and from some residence in Jimeta, Yola Metropolis; they were all screened for biofilm formation. Results: A total of 38.3% biofilm formation rate was recorded. Three types of bacterial isolates were identified in the biofilms of toothbrushes and wash basin junks, namely Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa at the prevalence rate of 48.0%, 29.1%, and 22.6%, respectively. Overall, 83.3% of the toothbrush biofilm were identified from female students, while 16.7% were from their male counterparts. Statistically, the frequency of biofilm formation showed a significant difference by gender (X 2 = 10.242, P 0.05. Conclusion: This study identified three microorganisms namely S. aureus, E. coli, and P. aeruginosa that were involved in wash basin junk biofilm formation. The findings also showed that occurrence of biofilm in females′ toothbrushes were significantly higher than in males′ (X 2 = 10.242, P < 0.05.

  3. The lipopeptide 6-2 produced by Bacillus amyloliquefaciens anti-CA has potent activity against the biofilm-forming organisms.

    Science.gov (United States)

    Song, Bo; Wang, Yu-Zhen; Wang, Guang-Yuan; Liu, Guang-Lei; Li, Wan-Zhong; Yan, Fang

    2016-07-15

    Both the whole cells and protoplasts of Pseudomonas aeruginosa PAO1 and Bacillus cereus, two biofilm-forming bacteria, were disrupted by the lipopeptide 6-2 produced by Bacillus amyloliquefaciens anti-CA. The lipopeptide 6-2 could also effectively inhibit the formation of biofilms and disperse pre-formed biofilms. Live/dead staining of the biofilms grown in the absence or presence of the lipopeptide 6-2 showed that more dead bacterial cells in the presence of the lipopeptide than those in the absence of the lipopeptide and biofilm formation was greatly reduced by the lipopeptide 6-2. Expression of the PslC gene related to exopolysaccharides in P. aeruginosa PAO1 was also inhibited. All these results demonstrated that the lipopeptide 6-2 produced by B. amyloliquefaciens anti-CA had a high activity against biofilm-forming bacteria. The lipopeptide 6-2 also killed the larvae of Balanus amphitrite and inhibit the germination of Laminaria japonica spore and growth of protozoa, all of which were the fouling organisms in marine environments. PMID:27184127

  4. Flo11p, drug efflux pumps, and the extracellular matrix cooperate to form biofilm yeast colonies

    Czech Academy of Sciences Publication Activity Database

    Váchová, Libuše; Šťovíček, V.; Hlaváček, Otakar; Chernyavskiy, Oleksandr; Štěpánek, L.; Kubínová, Lucie; Palková, Z.

    2011-01-01

    Roč. 194, č. 5 (2011), s. 679-687. ISSN 0021-9525 R&D Projects: GA ČR GA204/08/0718; GA MŠk(CZ) LC531; GA MŠk(CZ) LC06063 Institutional research plan: CEZ:AV0Z50200510; CEZ:AV0Z50110509 Keywords : CANDIDA-ALBICANS BIOFILMS * SACCHAROMYCES - CEREVISIAE * ABC TRANSPORTERS Subject RIV: EE - Microbiology, Virology Impact factor: 10.264, year: 2011

  5. Identification of individual biofilm-forming bacterial cells using Raman tweezers

    Czech Academy of Sciences Publication Activity Database

    Samek, Ota; Bernatová, Silvie; Ježek, Jan; Šiler, Martin; Šerý, Mojmír; Krzyžánek, Vladislav; Hrubanová, Kamila; Zemánek, Pavel; Holá, V.; Růžička, F.

    2015-01-01

    Roč. 20, č. 5 (2015), 051038:1-6. ISSN 1083-3668 R&D Projects: GA ČR GAP205/11/1687; GA MŠk(CZ) LO1212; GA MŠk ED0017/01/01 Institutional support: RVO:68081731 Keywords : Raman tweezers * Staphylococcus epidermidis * biofilm Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.859, year: 2014

  6. Low power gas discharge plasma mediated inactivation and removal of biofilms formed on biomaterials

    OpenAIRE

    Traba, Christian; Chen, Long; Liang, Jun F.

    2013-01-01

    The antibacterial activity of gas discharge plasma has been studied for quiet some time. However, high biofilm inactivation activity of plasma was only recently reported. Studies indicate that the etching effect associated with plasmas generated represent an undesired effect, which may cause live bacteria relocation and thus contamination spreading. Meanwhile, the strong etching effects from these high power plasmas may also alter the surface chemistry and affect the biocompatibility of bioma...

  7. Comparative Study of Antibiofilm Activity of Copper Oxide and Iron Oxide Nanoparticles Against Multidrug Resistant Biofilm Forming Uropathogens

    OpenAIRE

    Agarwala, Munin; Choudhury, Bula; Yadav, R. N. S.

    2014-01-01

    The effectiveness of the metal oxide nanoparticles viz. CuO and Fe2O3 as antibacterial agents against multidrug resistant biofilm forming bacteria was evaluated. CuO nanoparticles were also experimented for antibiofilm and time kill assay. The CuO displayed maximum antibacterial activity with zone of inhibition of (22 ± 1) mm against methicillin resistant Staphylococcus aureus (MRSA) followed by Escherichia coli (18 ± 1) mm. The Fe2O3 showed the zone of inhibition against MRSA of (14 ± 1) mm ...

  8. Comparison of two methods for quantification of Acinetobacter baumannii biofilm formation

    Directory of Open Access Journals (Sweden)

    Saghar Hendiani

    2014-01-01

    Full Text Available Introduction: ‏ Medical devices are made from a variety of materials such as polypropylene, polycarbonate, poly styrene, glass and etc. by attaching to this surfaces, Acinetobacter baumannii can form biofilms and then cause several device associated infections. Biofilms are communities of bacteria attached to the surfaces. In this study, biofilm formation ability in clinical isolates of Acinetobacter baumannii was assessed by two methods on different surfaces. Materials and methods: ‏ Biofilm formation by 75 clinical isolates of A. baumannii was evaluated on polycarbonate surface (microtiter plate and polypropylene surface (falcon by crystal violet and 2,3-Bis-(2-methoxy-4-nitro-5-sulfophenyl-2H-tetrazolium-5-carboxanilide salt (XTT tetrazolium sodium salt assay methods. Falcon or tube method was carried out under static and agitation conditions. Results: ‏ Results showed the most isolates can form biofilm but higher numbers of isolates form biofilm on polypropylene surface under agitation. XTT method confirmed strong biofilm formation ability of 10 isolates. Discussion and conclusion: Each of the two assays showed an excellent applicability for the quantification of biofilms. The Crystal violet assay is cheap, easy and is usually used for the quantification of biofilms formed by microorganisms but XTT is more reliable and repeatable. Most of A. baumannii isolates have potential to form biofilm on the medical devices which may result in device-associated infections.

  9. Influence of Limonia acidissima L. against the biofilm forming Aeromonas hydrophila isolated from fresh water fishes

    Directory of Open Access Journals (Sweden)

    Srinivasan Ponnuraj

    2015-04-01

    Full Text Available Limonia acidissima is a medicinal plant commonly used for multitude of ailments. In this context, the validation of traditionally used medicinal plant that the fruit extracts of L. acidissima exhibit antibiofilm activity against the predominant fish pathogen Aeromonas hydrophila was assessed. Among ten isolates of Aeromonas spp, KUAH1 showed strong biofilm formation and was studied further. The methanol (LA-M and ethyl acetate (LA-EA fraction of Limonia fruit extract clearly demonstrated significant (p ≤ 0.005 antibiofilm activity of 58 to 94% and 54 to 77% respectively. Furthermore, the potential of Limonia fruit extracts against some of the biofilm associated factors were tested by swimming and swarming motility assay, XTT and anti-haemolytic activity assay. Extracellular protein analysis revealed differential protein expression at molecular weight corresponding to 30-60 kDa. This is the first report on antibiofilm activity of L. acidissima fruit extracts, signifying the scope for development of complementary medicine to treat Aeromonas biofilm-associated infections.

  10. Rheology of biofilms

    OpenAIRE

    Winston, M.; Rupp, C.J.; Vinogradov, A.; Towler, B.W.; Adams, H; Stoodley, P

    2003-01-01

    The paper describes an experimental study concerning the mechanical properties of bacterial biofilms formed from the early dental plaque colonizer Streptoccocus mutans and pond water biofilms. Experiments reported in this paper demonstrate that both types of biofilms exhibit mechanical behavior similar to that of rheological fluids. The time-dependent properties of both biofilms have been modeled using the principles of viscoelasticity theory. The Burger model has been found to accurately re...

  11. Understanding, preventing and eradicating Klebsiella pneumoniae biofilms.

    Science.gov (United States)

    Ribeiro, Suzana Meira; Cardoso, Marlon Henrique; Cândido, Elizabete de Souza; Franco, Octávio Luiz

    2016-04-01

    The ability of pathogenic bacteria to aggregate and form biofilm represents a great problem for public health, since they present extracellular components that encase these micro-organisms, making them more resistant to antibiotics and host immune attack. This may become worse when antibiotic-resistant bacterial strains form biofilms. However, antibiofilm screens with different compounds may reveal potential therapies to prevent/treat biofilm infections. Here, we focused on Klebsiella pneumoniae, an opportunistic bacterium that causes different types of infections, including in the bloodstream, meninges, lungs, urinary system and at surgical sites. We also highlight aspects involved in the formation and maintenance of K. pneumoniae biofilms, as well as resistance and the emergence of new trends to combat this health challenge. PMID:27064296

  12. A novel model of chronic wounds: importance of redox imbalance and biofilm-forming bacteria for establishment of chronicity.

    Directory of Open Access Journals (Sweden)

    Sandeep Dhall

    Full Text Available Chronic wounds have a large impact on health, affecting ∼6.5 M people and costing ∼$25B/year in the US alone. We previously discovered that a genetically modified mouse model displays impaired healing similar to problematic wounds in humans and that sometimes the wounds become chronic. Here we show how and why these impaired wounds become chronic, describe a way whereby we can drive impaired wounds to chronicity at will and propose that the same processes are involved in chronic wound development in humans. We hypothesize that exacerbated levels of oxidative stress are critical for initiation of chronicity. We show that, very early after injury, wounds with impaired healing contain elevated levels of reactive oxygen and nitrogen species and, much like in humans, these levels increase with age. Moreover, the activity of anti-oxidant enzymes is not elevated, leading to buildup of oxidative stress in the wound environment. To induce chronicity, we exacerbated the redox imbalance by further inhibiting the antioxidant enzymes and by infecting the wounds with biofilm-forming bacteria isolated from the chronic wounds that developed naturally in these mice. These wounds do not re-epithelialize, the granulation tissue lacks vascularization and interstitial collagen fibers, they contain an antibiotic-resistant mixed bioflora with biofilm-forming capacity, and they stay open for several weeks. These findings are highly significant because they show for the first time that chronic wounds can be generated in an animal model effectively and consistently. The availability of such a model will significantly propel the field forward because it can be used to develop strategies to regain redox balance that may result in inhibition of biofilm formation and result in restoration of healthy wound tissue. Furthermore, the model can lead to the understanding of other fundamental mechanisms of chronic wound development that can potentially lead to novel therapies.

  13. Warming-induced changes in denitrifier community structure modulate the ability of phototrophic river biofilms to denitrify

    International Nuclear Information System (INIS)

    Microbial denitrification is the main nitrogen removing process in freshwater ecosystems. The aim of this study was to show whether and how water warming (+ 2.5 °C) drives bacterial diversity and structuring and how bacterial diversity affects denitrification enzymatic activity in phototrophic river biofilms (PRB). We used water warming associated to the immediate thermal release of a nuclear power plant cooling circuit to produce natural PRB assemblages on glass slides while testing 2 temperatures (mean temperature of 17 °C versus 19.5 °C). PRB were sampled at 2 sampling times during PRB accretion (6 and 21 days) in both temperatures. Bacterial community composition was assessed using ARISA. Denitrifier community abundance and denitrification gene mRNA levels were estimated by q-PCR and qRT-PCR, respectively, of 5 genes encoding catalytic subunits of the denitrification key enzymes. Denitrification enzyme activity (DEA) was measured by the acetylene-block assay at 20 °C. A mean water warming of 2.5 °C was sufficient to produce contrasted total bacterial and denitrifier communities and, therefore, to affect DEA. Indirect temperature effect on DEA may have varied between sampling time, increasing by up to 10 the denitrification rate of 6-day-old PRB and decreasing by up to 5 the denitrification rate of 21-day-old PRB. The present results suggest that indirect effects of warming through changes in bacterial community composition, coupled to the strong direct effect of temperature on DEA already demonstrated in PRB, could modulate dissolved nitrogen removal by denitrification in rivers and streams. - Highlights: •We produced river biofilms in 2 mean temperature conditions: 17 vs 19.5 °C. •We compared their denitrifiers' structuring and functioning in 6d- and 21d-old biofilms. •A difference of 2.5 °C produced contrasted denitrifier communities. •The indirect temperature effect on denitrification activity shifted between biofilm age. •Warming impact

  14. Warming-induced changes in denitrifier community structure modulate the ability of phototrophic river biofilms to denitrify

    Energy Technology Data Exchange (ETDEWEB)

    Boulêtreau, Stéphanie, E-mail: stephanie.bouletreau@univ-tlse3.fr [Université de Toulouse, UPS, INP, EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement), 118 route de Narbonne, F-31062 Toulouse (France); CNRS, EcoLab, F-31062 Toulouse (France); Lyautey, Emilie [Université de Toulouse, UPS, INP, EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement), 118 route de Narbonne, F-31062 Toulouse (France); CNRS, EcoLab, F-31062 Toulouse (France); Dubois, Sophie [Université de Bordeaux, EPOC - OASU, UMR 5805, Station Marine d' Arcachon, 2 rue du Professeur Jolyet, 33120 Arcachon (France); Compin, Arthur [Université de Toulouse, UPS, INP, EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement), 118 route de Narbonne, F-31062 Toulouse (France); CNRS, EcoLab, F-31062 Toulouse (France); Delattre, Cécile; Touron-Bodilis, Aurélie [EDF Recherche et Développement, LNHE (Laboratoire National d' Hydraulique et Environnement), 6 quai Watier, F-78401 Chatou (France); Mastrorillo, Sylvain [Université de Toulouse, UPS, INP, EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement), 118 route de Narbonne, F-31062 Toulouse (France); CNRS, EcoLab, F-31062 Toulouse (France); Garabetian, Frédéric [Université de Bordeaux, EPOC - OASU, UMR 5805, Station Marine d' Arcachon, 2 rue du Professeur Jolyet, 33120 Arcachon (France)

    2014-01-01

    Microbial denitrification is the main nitrogen removing process in freshwater ecosystems. The aim of this study was to show whether and how water warming (+ 2.5 °C) drives bacterial diversity and structuring and how bacterial diversity affects denitrification enzymatic activity in phototrophic river biofilms (PRB). We used water warming associated to the immediate thermal release of a nuclear power plant cooling circuit to produce natural PRB assemblages on glass slides while testing 2 temperatures (mean temperature of 17 °C versus 19.5 °C). PRB were sampled at 2 sampling times during PRB accretion (6 and 21 days) in both temperatures. Bacterial community composition was assessed using ARISA. Denitrifier community abundance and denitrification gene mRNA levels were estimated by q-PCR and qRT-PCR, respectively, of 5 genes encoding catalytic subunits of the denitrification key enzymes. Denitrification enzyme activity (DEA) was measured by the acetylene-block assay at 20 °C. A mean water warming of 2.5 °C was sufficient to produce contrasted total bacterial and denitrifier communities and, therefore, to affect DEA. Indirect temperature effect on DEA may have varied between sampling time, increasing by up to 10 the denitrification rate of 6-day-old PRB and decreasing by up to 5 the denitrification rate of 21-day-old PRB. The present results suggest that indirect effects of warming through changes in bacterial community composition, coupled to the strong direct effect of temperature on DEA already demonstrated in PRB, could modulate dissolved nitrogen removal by denitrification in rivers and streams. - Highlights: •We produced river biofilms in 2 mean temperature conditions: 17 vs 19.5 °C. •We compared their denitrifiers' structuring and functioning in 6d- and 21d-old biofilms. •A difference of 2.5 °C produced contrasted denitrifier communities. •The indirect temperature effect on denitrification activity shifted between biofilm age.

  15. Atomic force microscopy study of the structure function relationships of the biofilm-forming bacterium Streptococcus mutans

    Science.gov (United States)

    Cross, Sarah E.; Kreth, Jens; Zhu, Lin; Qi, Fengxia; Pelling, Andrew E.; Shi, Wenyuan; Gimzewski, James K.

    2006-02-01

    Atomic force microscopy (AFM) has garnered much interest in recent years for its ability to probe the structure, function and cellular nanomechanics inherent to specific biological cells. In particular, we have used AFM to probe the important structure-function relationships of the bacterium Streptococcus mutans. S. mutans is the primary aetiological agent in human dental caries (tooth decay), and is of medical importance due to the virulence properties of these cells in biofilm initiation and formation, leading to increased tolerance to antibiotics. We have used AFM to characterize the unique surface structures of distinct mutants of S. mutans. These mutations are located in specific genes that encode surface proteins, thus using AFM we have resolved characteristic surface features for mutant strains compared to the wild type. Ultimately, our characterization of surface morphology has shown distinct differences in the local properties displayed by various S. mutans strains on the nanoscale, which is imperative for understanding the collective properties of these cells in biofilm formation.

  16. Biofilms in Infections of the Eye

    Directory of Open Access Journals (Sweden)

    Paulo J. M. Bispo

    2015-03-01

    Full Text Available The ability to form biofilms in a variety of environments is a common trait of bacteria, and may represent one of the earliest defenses against predation. Biofilms are multicellular communities usually held together by a polymeric matrix, ranging from capsular material to cell lysate. In a structure that imposes diffusion limits, environmental microgradients arise to which individual bacteria adapt their physiologies, resulting in the gamut of physiological diversity. Additionally, the proximity of cells within the biofilm creates the opportunity for coordinated behaviors through cell–cell communication using diffusible signals, the most well documented being quorum sensing. Biofilms form on abiotic or biotic surfaces, and because of that are associated with a large proportion of human infections. Biofilm formation imposes a limitation on the uses and design of ocular devices, such as intraocular lenses, posterior contact lenses, scleral buckles, conjunctival plugs, lacrimal intubation devices and orbital implants. In the absence of abiotic materials, biofilms have been observed on the capsule, and in the corneal stroma. As the evidence for the involvement of microbial biofilms in many ocular infections has become compelling, developing new strategies to prevent their formation or to eradicate them at the site of infection, has become a priority.

  17. Design of a Simple Model of Candida albicans Biofilms Formed under Conditions of Flow: Development, Architecture and Drug Resistance

    OpenAIRE

    Uppuluri, Priya; Chaturvedi, Ashok K.; Ribot, Jose Lopez

    2009-01-01

    Candida albicans biofilms on most medical devices are exposed to a flow of body fluids that provide water and nutrients to the fungal cells. While C. albicans biofilms grown in vitro under static conditions have been exhaustively studied, the same is not true for biofilms developed under continuous flow of replenishing nutrients. Here, we describe a simple flow biofilm (FB) model that can be built easily with materials commonly available in most microbiological laboratories. We demonstrate th...

  18. Comparative efficacy of antibiotics in biofilms eradication formed by ESBL and non ESBL producing micro-organisms

    OpenAIRE

    Manu Chaudhary; Anurag Payasi

    2012-01-01

    Growth of bacterial cells within a biofilm complicate the treatment of infections. Therefore, in the present study biofilm eradication efficacy of (ceftriaxone and sulbactam plus EDTA; CSE1034) was compared with ceftriaxone alone, ceftriaxone plus EDTA and ceftriaxone plus sulbactam against biofilms of ESBL producing Escherichia coli, Klebsiella pneumoniae and Salmonella typhi. Susceptibility testing of each drug was performed on planktonic and biofilm cells in non ESBL producing and ESBL pro...

  19. Mini Seminar on Form Filling Ability of Self-Compacting Concrete

    DEFF Research Database (Denmark)

    Thrane, Lars Nyholm

    2005-01-01

    The Nordic mini-seminar “Form Filling Ability of Self-Compacting Concrete” took place on 3-4 November 2003 at the Danish Technological Institute in Taastrup, Denmark. The mini-seminar gathered 12 participants from Finland, Sweden, Norway and Denmark. The objective was to present and discuss recent...... developments of Self-Compacting Concrete in the Nordic countries. In general, the seminar included results and observations on the effect of fresh concrete behaviour, casting technique, and organisation on site on the filling ability, passing ability, and surface quality. The seminar had participants from the...

  20. Electro-active bio-films: formation, characterization and mechanisms

    International Nuclear Information System (INIS)

    Some bacteria, which are able to exchange electrons with a conductive material without mediator form on conductive surfaces electro-active bio-films. This bacterial property has been recently discovered (2001). Objectives of this work are to develop electro-active bio-films in various natural environments from indigenous flora, then through complementary electrochemical techniques (chrono-amperometry and cyclic voltammetry), to evaluate electro-activity of isolates coming from so-formed bio-films and to characterize mechanisms of electron transfer between bacteria and materials. First, electro-active bio-films have been developed under chrono-amperometry in garden compost and in water coming from Guyana mangrove. These bio-films were respectively able to use an electrode as electron acceptor (oxidation) or as electron donor (reduction). In compost, results obtained in chrono-amperometry and cyclic voltammetry suggest a two-step electron transfer: slow substrate consumption, then rapid electron transfer between bacteria and the electrode. Thereafter, the ability to reduce oxygen was demonstrated with cyclic voltammetry for facultative aerobic isolates from compost bio-films (Enterobacter spp. and Pseudomonas spp.) and for aerobic isolates obtained from marine electro-active bio-films (Roseobacter spp. in majority). Finally, bio-films inducing current increase in chrono-amperometry were developed in bioreactor with synthetic medium from a pure culture of isolates. Hence, for the first time, electro-activity of several anaerobic strains of Geobacter bremensis isolated from compost bio-films was highlighted. (author)

  1. Characterization of Mannheimia haemolytica biofilm formation in vitro.

    Science.gov (United States)

    Boukahil, Ismail; Czuprynski, Charles J

    2015-01-30

    Mannheimia haemolytica is the primary bacterial agent in the bovine respiratory disease complex. It is thought that M. haemolytica colonizes the tonsillar crypts of cattle as a commensal and subsequently descends into the lungs to cause disease. Many bacterial species persist in the host as biofilms. There is limited information about the ability of M. haemolytica to form biofilms. The aim of this study was to develop an in vitro model for M. haemolytica biofilm formation. We found that M. haemolytica required at least 36 h to form robust biofilms on plastic in vitro when incubated in RPMI-1640 tissue culture medium at 37 °C, with maximal biofilm formation being evident at 48 h. Biofilm formation was inhibited by adding the monosaccharides d(+) galactose and d(+) mannose to the growth medium. Addition of antibodies to the M. haemolytica surface protein OmpA also reduced biofilm formation. Upon evaluating the macromolecules within the biofilm extracellular polymeric substance we found it contained 9.7 μg/cm(2) of protein, 0.81 μg/cm(2) of total carbohydrate, and 0.47 μg/cm(2) of extracellular DNA. Furthermore, proteinase K treatment significantly decreased biofilms (Pbovine upper respiratory tract. PMID:25480166

  2. Escherichia coli and Enterococcus faecalis are able to incorporate and enhance a pre-formed Gardnerella vaginalis biofilm.

    Science.gov (United States)

    Castro, Joana; Machado, Daniela; Cerca, Nuno

    2016-04-01

    Gardnerella vaginalis is the most frequent microorganism found in bacterial vaginosis (BV), while Escherichia coli and Enterococcus faecalis are amongst the most frequent pathogens found in urinary tract infections (UTIs). This study aimed to evaluate possible interactions between UTIs pathogens and G. vaginalis using an in vitro dual-species biofilm model. Our results showed that dual-species biofilms reached significantly higher bacterial concentration than monospecies biofilms. Moreover, visualization of dual-populations species in the biofilms, using the epifluorescence microscopy, revealed that all of the urogenital pathogens coexisted with G. vaginalis. In conclusion, our work demonstrates that uropathogens can incorporate into mature BV biofilms. PMID:26782142

  3. Comparison of two methods for quantification of Acinetobacter baumannii biofilm formation

    OpenAIRE

    Saghar Hendiani; Ahya Abdi-Ali; Parisa Mohammadi

    2014-01-01

    Introduction: ‏ Medical devices are made from a variety of materials such as polypropylene, polycarbonate, poly styrene, glass and etc. by attaching to this surfaces, Acinetobacter baumannii can form biofilms and then cause several device associated infections. Biofilms are communities of bacteria attached to the surfaces. In this study, biofilm formation ability in clinical isolates of Acinetobacter baumannii was assessed by two methods on different surfaces. Materials and methods: ‏ Biof...

  4. Proteus mirabilis biofilm - Qualitative and quantitative colorimetric methods-based evaluation

    OpenAIRE

    Joanna Kwiecinska-Piróg; Tomasz Bogiel; Krzysztof Skowron; Ewa Wieckowska; Eugenia Gospodarek

    2014-01-01

    Proteus mirabilis strains ability to form biofilm is a current topic of a number of research worldwide. In this study the biofilm formation of P. mirabilis strains derived from urine of the catheterized and non-catheterized patients has been investigated. A total number of 39 P. mirabilis strains isolated from the urine samples of the patients of dr Antoni Jurasz University Hospital No. 1 in Bydgoszcz clinics between 2011 and 2012 was used. Biofilm formation was evaluated using two independen...

  5. The Ciprofloxacin Impact on Biofilm Formation by Proteus Mirabilis and P. Vulgaris Strains

    OpenAIRE

    Kwiecinska-Pirog, Joanna; Skowron, Krzysztof; Bartczak, Wojciech; Gospodarek-Komkowska, Eugenia

    2016-01-01

    Background Proteus spp. bacilli belong to opportunistic human pathogens, which are primarily responsible for urinary tract and wound infections. An important virulence factor is their ability to form biofilms that greatly reduce the effectiveness of antibiotics in the site of infection. Objectives The aim of this study was to determine the value of the minimum concentration of ciprofloxacin that eradicates a biofilm of Proteus spp. strains. Materials and Methods A biofilm formation of 20 stra...

  6. Patterns of virulence gene expression differ between biofilm and tissue communities of Streptococcus pyogenes.

    Science.gov (United States)

    Cho, Kyu Hong; Caparon, Michael G

    2005-09-01

    The ability of Streptococcus pyogenes to form biofilm-like bacterial communities during infection of soft tissue has suggested that the capacity to produce biofilm may be important for pathogenesis. To examine this relationship, a panel of mutants was evaluated for their ability to form biofilm on abiotic surfaces in several assays. Several established virulence factors were crucial for biofilm formation, including the M protein, required for initial cell-surface interactions, and the hyaluronic acid capsule, required for subsequent maturation into a three-dimensional structure. Mutants lacking the transcription regulators Mga and CovR (CsrR) also failed to form biofilm. Comparison of transcriptional profiles revealed differential regulation of approximately 25% of the genome upon adaptation to biofilm. During infection of zebrafish, several virulence factors (notably cysteine protease and streptokinase) were regulated in a biofilm-like manner. However, the overall profile of virulence factor expression indicated that tissue communities have a pattern of gene expression different from biofilm. Taken together, these data show that while biofilm and tissue communities have many characteristics in common, that biofilm reproduces only a subset of the myriad cues used by tissue communities for regulation of virulence. PMID:16135223

  7. Effect of glucose on Listeria monocytogenes biofilm formation, and assessment of the biofilm's sanitation tolerance.

    Science.gov (United States)

    Kyoui, Daisuke; Hirokawa, Eri; Takahashi, Hajime; Kuda, Takashi; Kimura, Bon

    2016-08-01

    Listeria monocytogenes is an important cause of human foodborne infections and its ability to form biofilms is a serious concern to the food industry. To reveal the effect of glucose conditions on biofilm formation of L. monocytogenes, 20 strains were investigated under three glucose conditions (0.1, 1.0, and 2.0% w v(-1)) by quantifying the number of cells in the biofilm and observing the biofilm structure after incubation for 24, 72, and 168 h. In addition, the biofilms were examined for their sensitivity to sodium hypochlorite. It was found that high concentrations of glucose reduced the number of viable cells in the biofilms and increased extracellular polymeric substance production. Moreover, biofilms formed at a glucose concentration of 1.0 or 2.0% were more resistant to sodium hypochlorite than those formed at a glucose concentration of 0.1%. This knowledge can be used to help design the most appropriate sanitation strategy. PMID:27353113

  8. Biofilm formation by Pseudoalteromonas ruthenica and its removal by chlorine.

    Science.gov (United States)

    Saravanan, Periasamy; Nancharaiah, Y Venkata; Venugopalan, Vayalam P; Rao, T Subba; Jayachandran, Seetharaman

    2006-01-01

    The distribution of a recently described marine bacterium, SBT 033 GenBank Accession No. AY723742), Pseudoalteromonas ruthenica, at the seawater intake point, outfall and mixing point of an atomic power plant is described, and its ability to form biofilm was investigated. The effectiveness of the antifouling biocide chlorine in the inactivation of planktonic as well as biofilm cells of P. ruthenica was studied in the laboratory. The results show that the planktonic cells were more readily inactivated than the cells enclosed in a biofilm matrix. Viable counting showed that P. ruthenica cells in biofilms were up to 10 times more resistant to chlorine than those in liquid suspension. Using confocal laser scanning microscopy it was shown that significant detachment of P. ruthenica biofilm developed on a glass substratum could be accomplished by treatment with a dose of 1 mg l-1 chlorine. Chlorine-induced detachment led to a significant reduction in biofilm thickness (up to 69%) and substratum coverage (up to 61%), after 5-min contact time. The results show that P. ruthenica has a remarkable ability to form biofilms but chlorine, a common biocide, can be used to effectively kill and detach these biofilms. PMID:17178570

  9. Resource function of conceptual and metacognitive abilities in adolescents with different forms of dysontogenesis.

    Directory of Open Access Journals (Sweden)

    Kholodnaya, M.

    2015-07-01

    Full Text Available This study investigated the level of conceptual and metacognitive abilities and their interaction in adolescents with different forms of dysontogenesis. The total sample (N= 173 included four groups of young adolescents (11-12 years old: with normal development, with infantile cerebral palsy (CP, with attention deficit hyperactivity disorder (ADHD, and with delayed intellectual development (DID. We measured the adolescents’ performance on tests of conceptual abilities (the use of categories at different grades of generalization, the discovery of abstract meaning and implicit connections between concepts and metacognitive abilities (attention selectivity, as measured by Mtinsterberg’s test and the understanding of hidden pictures, and attention organization, as measured by indices of cognitive styles. The results showed, first, that in comparison with normal adolescents, the adolescents with CP and ADHD had a deficit of metacognitive abilities, but they did not differ in rates of conceptual abilities. As for adolescents with DID, even though they had lower rates of conceptual abilities and attention selectivity, they did not differ from the “norm” group on some indices of attention organization. Second, a tendency for the disintegration of conceptual and metacognitive abilities (as measured by correlation and factor analysis was most clearly seen in the adolescents with ADHD and DID. The adolescents with CP and ADHD had conceptual (categorial and generative abilities as a mental resource, and the adolescents with DID had metacognitive abilities as a mental resource. The resource function of conceptual and metacognitive abilities was determined not only by their level but also by the extent of their interaction (integration.

  10. Density and glass forming ability in amorphous atomic alloys: The role of the particle softness

    Science.gov (United States)

    Douglass, Ian; Hudson, Toby; Harrowell, Peter

    2016-04-01

    A key property of glass forming alloys, the anomalously small volume difference with respect to the crystal, is shown to arise as a direct consequence of the soft repulsive potentials between metals. This feature of the inter-atomic potential is demonstrated to be responsible for a significant component of the glass forming ability of alloys due to the decrease in the enthalpy of fusion and the associated depression of the freezing point.

  11. Career Adapt-Abilities Scale-Belgium Form: Psychometric Characteristics and Construct Validity

    Science.gov (United States)

    Dries, Nicky; Van Esbroeck, Raoul; van Vianen, Annelies E. M.; De Cooman, Rein; Pepermans, Roland

    2012-01-01

    The Dutch version of the Career Adapt-Abilities Scale-Belgium Form (CAAS-Belgium) consists of four scales, each with six items, which measure concern, control, curiosity, and confidence as psychosocial resources for managing occupational transitions, developmental tasks, and work traumas. A pilot survey was administered to 700 high school,…

  12. Career Adapt-Abilities Scale--Brazilian Form: Psychometric Properties and Relationships to Personality

    Science.gov (United States)

    Teixeira, Marco Antonio Pereira; Bardagi, Marucia Patta; Lassance, Maria Celia Pacheco; Magalhaes, Mauro de Oliveira; Duarte, Maria Eduarda

    2012-01-01

    The Career Adapt-Abilities Scale--Brazilian Form (CAASBrazil) consists of four scales which measure concern, control, curiosity, and confidence as psychosocial resources for managing occupational transitions, developmental tasks, and work traumas. Internal consistency estimates for the subscale and total scores ranged from good to excellent. The…

  13. Bacteriophages and Biofilms

    OpenAIRE

    Harper, David R; Helena M. R. T. Parracho; James Walker; Richard Sharp; Gavin Hughes; Maria Werthén; Susan Lehman; Sandra Morales

    2014-01-01

    Biofilms are an extremely common adaptation, allowing bacteria to colonize hostile environments. They present unique problems for antibiotics and biocides, both due to the nature of the extracellular matrix and to the presence within the biofilm of metabolically inactive persister cells. Such chemicals can be highly effective against planktonic bacterial cells, while being essentially ineffective against biofilms. By contrast, bacteriophages seem to have a greater ability to target this commo...

  14. Iron and Acinetobacter baumannii Biofilm Formation

    Directory of Open Access Journals (Sweden)

    Valentina Gentile

    2014-08-01

    Full Text Available Acinetobacter baumannii is an emerging nosocomial pathogen, responsible for infection outbreaks worldwide. The pathogenicity of this bacterium is mainly due to its multidrug-resistance and ability to form biofilm on abiotic surfaces, which facilitate long-term persistence in the hospital setting. Given the crucial role of iron in A. baumannii nutrition and pathogenicity, iron metabolism has been considered as a possible target for chelation-based antibacterial chemotherapy. In this study, we investigated the effect of iron restriction on A. baumannii growth and biofilm formation using different iron chelators and culture conditions. We report substantial inter-strain variability and growth medium-dependence for biofilm formation by A. baumannii isolates from veterinary and clinical sources. Neither planktonic nor biofilm growth of A. baumannii was affected by exogenous chelators. Biofilm formation was either stimulated by iron or not responsive to iron in the majority of isolates tested, indicating that iron starvation is not sensed as an overall biofilm-inducing stimulus by A. baumannii. The impressive iron withholding capacity of this bacterium should be taken into account for future development of chelation-based antimicrobial and anti-biofilm therapies.

  15. Biofilm Formation Mechanisms of Pseudomonas aeruginosa Predicted via Genome-Scale Kinetic Models of Bacterial Metabolism.

    Science.gov (United States)

    Vital-Lopez, Francisco G; Reifman, Jaques; Wallqvist, Anders

    2015-10-01

    A hallmark of Pseudomonas aeruginosa is its ability to establish biofilm-based infections that are difficult to eradicate. Biofilms are less susceptible to host inflammatory and immune responses and have higher antibiotic tolerance than free-living planktonic cells. Developing treatments against biofilms requires an understanding of bacterial biofilm-specific physiological traits. Research efforts have started to elucidate the intricate mechanisms underlying biofilm development. However, many aspects of these mechanisms are still poorly understood. Here, we addressed questions regarding biofilm metabolism using a genome-scale kinetic model of the P. aeruginosa metabolic network and gene expression profiles. Specifically, we computed metabolite concentration differences between known mutants with altered biofilm formation and the wild-type strain to predict drug targets against P. aeruginosa biofilms. We also simulated the altered metabolism driven by gene expression changes between biofilm and stationary growth-phase planktonic cultures. Our analysis suggests that the synthesis of important biofilm-related molecules, such as the quorum-sensing molecule Pseudomonas quinolone signal and the exopolysaccharide Psl, is regulated not only through the expression of genes in their own synthesis pathway, but also through the biofilm-specific expression of genes in pathways competing for precursors to these molecules. Finally, we investigated why mutants defective in anthranilate degradation have an impaired ability to form biofilms. Alternative to a previous hypothesis that this biofilm reduction is caused by a decrease in energy production, we proposed that the dysregulation of the synthesis of secondary metabolites derived from anthranilate and chorismate is what impaired the biofilms of these mutants. Notably, these insights generated through our kinetic model-based approach are not accessible from previous constraint-based model analyses of P. aeruginosa biofilm

  16. Diversity assessment of Listeria monocytogenes biofilm formation: Impact of growth condition, serotype and strain origin

    NARCIS (Netherlands)

    Kadam, S.R.; Besten, den H.M.W.; Veen, van der S.; Zwietering, M.H.; Moezelaar, R.; Abee, T.

    2013-01-01

    The foodborne pathogen Listeria monocytogenes has the ability to produce biofilms in food-processing environments and then contaminate food products, which is a major concern for food safety. The biofilm forming behavior of 143 L. monocytogenes strains was determined in four different media that wer

  17. Comparative Evaluation of Antimicrobial Activity of Pomegranate-Containing Mouthwash Against Oral-Biofilm Forming Organisms: An Invitro Microbial Study

    Science.gov (United States)

    Dabholkar, Charuta Sadanand; Shah, Mona; Bajaj, Monika; Doshi, Yogesh

    2016-01-01

    Introduction Pomegranate is considered “A pharmacy unto itself”. Hydrolysable tannins called punicalagins which have free scavenging properties are the most abundant polyphenols found in pomegranate-containing mouthwash. Aim To evaluate antimicrobial effect of pomegranate- containing mouthwash on oral biofilm-forming bacteria. Materials and Methods The mouthwashes used were divided into three groups- Group A: Chlorhexidine mouthwash (Hexidine); Group B: Herbal Mouthwash (Hiora) and Group C: Pomegranate-containing Mouthwash (Life-extension). Each mouthwash was diluted to five different concentrations. Reference strains of Streptococcus mutans (S.mutans) (ATCC 25175), Streptococcus salivarius (S.salivarius) (ATCC 7073), and Aggregatibacter actinomycetemcomitans (A.a) (NCTC 9710) were selected as being colonizers in dental biofilm formation. On each culture plate, five wells of 5mm were prepared and mouthwashes with different concentrations were added, followed by incubation in a CO2 jar for 24 hours at 37°C. Inhibition zone diameters were measured using a digital caliper. Results Chlorhexidine (0.12%) presented a zone of inhibition between 38.46% to 96.15% for all the three organisms, while Hiora presented zone of inhibition ranging from 33.33% to 69.23% but was resistant at <10 ml of dilution. Pomegranate mouthwash presented a zone of inhibition ranging from 38.48 to 57.69%, but was resistant at <10ml for S.mutans, and <25ml for A.a and S.salivarius. ANOVA test was done to compare the dilution of mouthwashes for a particular organism and Tukey’s multiple comparison tests were done to find the exact difference. A significant difference was seen between all the three groups at 50ml and 75 ml of dilution. At 75 ml concentration, a statistical difference was found between Groups B & C and Groups A & B; and at 50 ml between Groups A&C. Conclusion All the three types of mouthwash exhibit anti-microbial activity against biofilm forming organisms but at varying

  18. Gardnerella vaginalis outcompetes 29 other bacterial species isolated from patients with bacterial vaginosis, using in an in vitro biofilm formation model.

    Science.gov (United States)

    Alves, Patrícia; Castro, Joana; Sousa, Cármen; Cereija, Tatiana B; Cerca, Nuno

    2014-08-15

    Despite the worldwide prevalence of bacterial vaginosis (BV), its etiology is still unknown. Although BV has been associated with the presence of biofilm, the ability of BV-associated bacteria to form biofilms is still largely unknown. Here, we isolated 30 BV-associated species and characterized their virulence, using an in vitro biofilm formation model. Our data suggests that Gardnerella vaginalis had the highest virulence potential, as defined by higher initial adhesion and cytotoxicity of epithelial cells, as well as the greater propensity to form a biofilm. Interestingly, we also demonstrated that most of the BV-associated bacteria had a tendency to grow as biofilms. PMID:24596283

  19. Role of type 1 and type 3 fimbriae in Klebsiella pneumoniae biofilm formation

    Directory of Open Access Journals (Sweden)

    Krogfelt Karen A

    2010-06-01

    Full Text Available Abstract Background Klebsiella pneumoniae is an important gram-negative opportunistic pathogen causing primarily urinary tract infections, respiratory infections, and bacteraemia. The ability of bacteria to form biofilms on medical devices, e.g. catheters, has a major role in development of many nosocomial infections. Most clinical K. pneumoniae isolates express two types of fimbrial adhesins, type 1 fimbriae and type 3 fimbriae. In this study, we characterized the role of type 1 and type 3 fimbriae in K. pneumoniae biofilm formation. Results Isogenic fimbriae mutants of the clinical K. pneumoniae isolate C3091 were constructed, and their ability to form biofilm was investigated in a flow cell system by confocal scanning laser microscopy. The wild type strain was found to form characteristic biofilm and development of K. pneumoniae biofilm occurred primarily by clonal growth, not by recruitment of planktonic cells. Type 1 fimbriae did not influence biofilm formation and the expression of type 1 fimbriae was found to be down-regulated in biofilm forming cells. In contrast, expression of type 3 fimbriae was found to strongly promote biofilm formation. Conclusion By use of well defined isogenic mutants we found that type 3 fimbriae, but not type 1 fimbriae, strongly promote biofilm formation in K. pneumoniae C3091. As the vast majority of clinical K. pneumoniae isolates express type 3 fimbriae, this fimbrial adhesin may play a significant role in development of catheter associated K. pneumoniae infections.

  20. Escherichia coli and Enterococcus faecalis are able to incorporate and enhance a pre-formed Gardnerella vaginalis biofilm

    OpenAIRE

    Castro, Joana; Machado, D; Cerca, Nuno

    2016-01-01

    Gardnerella vaginalis is the most frequent microorganism found in bacterial vaginosis (BV), while Escherichia coli and Enterococcus faecalis are amongst the most frequent pathogens found in urinary tract infections (UTIs). This study aimed to evaluate possible interactions between UTIs pathogens and G. vaginalis using an in vitro dual-species biofilm model. Our results showed that dual-species biofilms reached significantly higher bacterial concentration than mono-species biofilms. Moreover, ...

  1. Fimbriae have distinguishable roles in Proteus mirabilis biofilm formation.

    Science.gov (United States)

    Scavone, Paola; Iribarnegaray, Victoria; Caetano, Ana Laura; Schlapp, Geraldine; Härtel, Steffen; Zunino, Pablo

    2016-07-01

    Proteus mirabilis is one of the most common etiological agents of complicated urinary tract infections, especially those associated with catheterization. This is related to the ability of P. mirabilis to form biofilms on different surfaces. This pathogen encodes 17 putative fimbrial operons, the highest number found in any sequenced bacterial species so far. The present study analyzed the role of four P. mirabilis fimbriae (MR/P, UCA, ATF and PMF) in biofilm formation using isogenic mutants. Experimental approaches included migration over catheter, swimming and swarming motility, the semiquantitative assay based on adhesion and crystal violet staining, and biofilm development by immunofluorescence and confocal microscopy. Different assays were performed using LB or artificial urine. Results indicated that the different fimbriae contribute to the formation of a stable and functional biofilm. Fimbriae revealed particular associated roles. First, all the mutants showed a significantly reduced ability to migrate across urinary catheter sections but neither swimming nor swarming motility were affected. However, some mutants formed smaller biofilms compared with the wild type (MRP and ATF) while others formed significantly larger biofilms (UCA and PMF) showing different bioarchitecture features. It can be concluded that P. mirabilis fimbriae have distinguishable roles in the generation of biofilms, particularly in association with catheters. PMID:27091004

  2. Ambroxol influences voriconazole resistance of Candida parapsilosis biofilm.

    Science.gov (United States)

    Pulcrano, Giovanna; Panellis, Dimitrios; De Domenico, Giovanni; Rossano, Fabio; Catania, Maria Rosaria

    2012-06-01

    The ability to form biofilm on different surfaces is typical of most Candida species. Microscopic structure and genetic aspects of fungal biofilms have been the object of many studies because of very high resistance to antimycotic agents because of the scarce permeability of the external matrix and to the alterations in cell metabolism. In our study, 31 isolates of Candida parapsilosis, isolated from bloodstream infections, were tested for their ability to produce biofilm and were found to be good producers. The susceptibility to voriconazole, assayed by colorimetrical XTT assay, revealed a very elevated minimum inhibitory concentrations for sessile cells in comparison with planktonic ones. The addition of ambroxol, a mucolytic agent, increased the susceptibility of biofilm forming cells to voriconazole. Expression of the efflux pump genes CDR and MDR was analyzed in biofilms alone or treated with ambroxol, evidencing a role of ambroxol in the expression of genes involved in azole resistance mechanisms of C. parapsilosis biofilms. In conclusion, our data seem to encourage the use of different substances in combination with classical antimycotics, with the aim of finding a solution to the increasing problem of the resistance of biofilms formed on medical devices by nonalbicans Candida species. PMID:22315984

  3. Sodium dodecyl sulfate allows the persistence and recovery of biofilms of Pseudomonas fluorescens formed under different hydrodynamic conditions

    OpenAIRE

    Simões, M.; Simões, Lúcia C.; Pereira, Maria Olívia; Vieira, M. J.

    2008-01-01

    The effect of the anionic surfactant sodium dodecyl sulfate (SDS) on Pseudomonas fluorescens biofilms was investigated using flow cell reactors with stainless steel substrata, under turbulent (Re=5200) and laminar (Re=2000) flow. Steady-state biofilms were exposed to SDS in single doses (0.5, 1, 3 and 7 mM) and biofilm respiratory activity and mass measured at 0, 3, 7 and 12 h after the SDS application. The effect of SDS on biofilm mechanical stability was assessed using a rotatin...

  4. 3′,5′-Cyclic Diguanylic Acid Reduces the Virulence of Biofilm-Forming Staphylococcus aureus Strains in a Mouse Model of Mastitis Infection

    OpenAIRE

    Brouillette, Eric; Hyodo, Mamoru; Hayakawa, Yoshihiro; Karaolis, David K.R.; Malouin, François

    2005-01-01

    The cyclic dinucleotide 3′,5′-cyclic diguanylic acid (c-di-GMP) is a naturally occurring small molecule that regulates important signaling systems in bacteria. We have recently shown that c-di-GMP inhibits Staphylococcus aureus biofilm formation in vitro and its adherence to HeLa cells. We now report that c-di-GMP treatment has an antimicrobial and antipathogenic activity in vivo and reduces, in a dose-dependent manner, bacterial colonization by biofilm-forming S. aureus strains in a mouse mo...

  5. Antibiotic pressure mediated selection of non-biofilm forming strain of Elizabethkingia meningosepticum causing fatal nosocomial meningitis in a term infant

    Directory of Open Access Journals (Sweden)

    Sumit Rai

    2013-01-01

    Full Text Available We describe a fatal case of hospital acquired meningitis in a term infant due to the antibiotic pressure mediated selection of Elizabethkingia meningosepticum. The antibiotics were administered for multi-drug resistant Acinetobacter baumannii infection. The strain was also phenotypically characterized for beta lactamase production, biofilm forming capability and resistance to in use disinfectants.

  6. Comparative pyrosequencing analysis of bacterial community change in biofilm formed on seawater reverse osmosis membrane.

    Science.gov (United States)

    Kim, In S; Lee, Jinwook; Kima, Sung-Jo; Yu, Hye-Weon; Jang, Am

    2014-01-01

    The change in bacterial community structure induced by bacterial competition and succession was investigated during seawater reverse osmosis (SWRO) in order to elucidate a possible link between the bacterial consortium on SWRO membranes and biofouling. To date, there has been no definitive characterization of the microbial diversity in SWRO in terms of distinguishing time-dependent changes in the richness or abundance of bacterial species. For bacterial succession within biofilms on the membrane surface, SWRO using a cross-flow filtration membrane test unit was operated for 5 and 100h, respectively. As results of the pyrosequencing analysis, bacterial communities differed considerably among seawater and the 5 and 100 h samples. From a total of 33,876 pyrosequences (using a 95% sequence similarity), there were less than 1% of shared species, confirming the influence of the operational time factor and lack of similarity of these communities. During SWRO operation, the abundance of Pseudomonas stutzeri BBSPN3 (GU594474) belonging to gamma-Proteobacteria suggest that biofouling of SWRO membrane might be driven by the dominant influence of a specific species. In addition, among the bacterial competition of five bacterial species (Pseudomonas aeruginosa, Bacillus sp., Rhodobacter sp., Flavobacterium sp., and Mycobacterium sp.) competing for bacterial colonization on the SWRO membrane surfaces, it was exhibited that Bacillus sp. was the most dominant. The dominant influences ofPseudomonas sp. and Bacillus sp. on biofouling during actual SWRO is decisive depending on higher removal efficiency of the seawater pretreatment. PMID:24600849

  7. Estimation of the enterprise marketing activity by criterion on future abilities creation to form demand

    OpenAIRE

    L.V. Potrashkova

    2015-01-01

    The aim of the article. The aim of the article is to develop theoretic grounds to calculate enterprise marketing activity factors, which characterize its long term consequences with production demand formation in future. The results of the analysis. One suggests to estimate enterprise marketing activity by criterion on future enterprise abilities creation to form production demand. That’s why enterprise marketing activity factors have to include enterprise marketing potential factors. Thes...

  8. Streptococcus pneumoniae biofilm formation and dispersion during colonization and disease

    Directory of Open Access Journals (Sweden)

    Yashuan eChao

    2015-01-01

    Full Text Available Streptococcus pneumoniae (the pneumococcus is a common colonizer of the human nasopharynx. Despite a low rate of invasive disease, the high prevalence of colonization results in millions of infections and over 1 million deaths per year, mostly in individuals under the age of 5 and the elderly. Colonizing pneumococci form well-organized biofilm communities in the nasopharyngeal environment, but the specific role of biofilms and their interaction with the host during colonization and disease is not yet clear. Pneumococci in biofilms are highly resistant to antimicrobial agents and this phenotype can be recapitulated when pneumococci are grown on respiratory epithelial cells under conditions found in the nasopharyngeal environment. Pneumococcal biofilms display lower levels of virulence in vivo and provide an optimal environment for increased genetic exchange both in vitro and in vivo, with increased natural transformation seen during co-colonization with multiple strains. Biofilms have also been detected on mucosal surfaces during pneumonia and middle ear infection, although the role of these biofilms in the disease process is debated. Recent studies have shown that changes in the nasopharyngeal environment caused by concomitant virus infection, changes in the microflora, inflammation, or other host assaults trigger active release of pneumococci from biofilms. These dispersed bacteria have distinct phenotypic properties and transcriptional profiles different from both biofilm and broth-grown, planktonic bacteria, resulting in a significantly increased virulence in vivo.In this review we discuss the properties of pneumococcal biofilms, the role of biofilm formation during pneumococcal colonization, including their propensity for increased ability to exchange genetic material, as well as mechanisms involved in transition from asymptomatic biofilm colonization to dissemination and disease of otherwise sterile sites. Greater understanding of

  9. Effects of gravity field onglass forming ability in ZrTiCuNiBe alloy

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The solidification and glass forming ability of Zr41Ti14Cu12.5Ni10Be22.5 bulk glassy forming alloy is investigated by Bridgman unidirectional solidification at different growth velocities under different gravity field orientations. Large differences in glass formation, undercooling and crystallization morphology on different solidification conditions have been found and discussed from the point of view of gravity induced convection. The results are useful for understanding the nucleation and growth in the melt and glass formation mechanism in the alloy.

  10. The differentiated approach in forming swimming abilities and skills of students

    Directory of Open Access Journals (Sweden)

    Nikolskiy A.U.

    2010-09-01

    Full Text Available It is considered the directions of organization and methods of conducting of lessons with students. In experiment took part students of the 17-20 years old. The criteria of forming of typological educational groups are presented on the initial stage of teaching swimming of students. The degree of connection of the hereditarily conditioned swimming coordinating inclination is certain with the indexes of formed swimming abilities and skills of students. It is well-proven that a process of capture motive habits is under unreserved influence of conservative heredity of individual.

  11. Biofilm formation among Candida albicans isolated from vagina

    OpenAIRE

    2014-01-01

    Purpose: Study was conducted in a rural tertiary care hospital with a purpose to demonstrate the biofilm forming abilities of C. albicans isolated from cases of vulvovaginal candidiasis and asymptomatic carriers.Material and Methods: C. albicans was isolated and identified by standard laboratory techniques. Biofilm formation in vitro was tested using the 96 well microtitre plate method with crystal violet staining.Results: Overall rate of Candida isolation in study subjects was 40%. Candida i...

  12. Importance of Candida-bacterial polymicrobial biofilms in disease

    OpenAIRE

    Harriott, Melphine M.; Noverr, Mairi C.

    2011-01-01

    Candida albicans is the most prevalent human fungal pathogen, with an ability to inhabit diverse host niches and cause disease in both immunocompetent and immunocompromised individuals. C. albicans also readily forms biofilms on indwelling medical devices and mucosal tissues, which serve as an infectious reservoir that is difficult to eradicate, and can lead to lethal systemic infections. Biofilm formation occurs within a complex milieu of host factors and other members of the human microbiot...

  13. Mucosal biofilms of Candida albicans

    OpenAIRE

    Ganguly, Shantanu; Mitchell, Aaron P.

    2011-01-01

    Biofilms are microbial communities that form on surfaces and are embedded in an extracellular matrix. C. albicans forms pathogenic mucosal biofilms that are evoked by changes in host immunity or mucosal ecology. Mucosal surfaces are inhabited by many microbial species; hence these biofilms are polymicrobial. Several recent studies have applied paradigms of biofilm analysis to study mucosal C. albicans infections. These studies reveal that the Bcr1 transcription factor is a master regulator of...

  14. Characterization of structures in biofilms formed by a Pseudomonas fluorescens isolated from soil

    OpenAIRE

    Wu Siva; McDonald Kent; Pandita Ragini; O'Keeffe Teresa; Kainović Aleksandra; Baum Marc M; Webster Paul

    2009-01-01

    Abstract Background Microbial biofilms represent an incompletely understood, but fundamental mode of bacterial growth. These sessile communities typically consist of stratified, morphologically-distinct layers of extracellular material, where numerous metabolic processes occur simultaneously in close proximity. Limited reports on environmental isolates have revealed highly ordered, three-dimensional organization of the extracellular matrix, which may hold important implications for biofilm ph...

  15. Effects of partitioned enthalpy of mixing on glass-forming ability

    International Nuclear Information System (INIS)

    We explore the inherent reason at atomic level for the glass-forming ability of alloys by molecular simulation, in which the effect of partitioned enthalpy of mixing is studied. Based on Morse potential, we divide the enthalpy of mixing into three parts: the chemical part (Δ Enn), strain part (Δ Estrain), and non-bond part (Δ Ennn). We find that a large negative Δ Enn value represents strong AB chemical bonding in AB alloy and is the driving force to form a local ordered structure, meanwhile the transformed local ordered structure needs to satisfy the condition (Δ Enn/2 + Δ Estrain) < 0 to be stabilized. Understanding the chemical and strain parts of enthalpy of mixing is helpful to design a new metallic glass with a good glass forming ability. Moreover, two types of metallic glasses (i.e., “strain dominant” and “chemical dominant”) are classified according to the relative importance between chemical effect and strain effect, which enriches our knowledge of the forming mechanism of metallic glass. Finally, a soft sphere model is established, different from the common hard sphere model

  16. Correlation between liquid structure and glass forming ability in glassy Ag-based binary alloys

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The atomic structures of liquid Ag-based binary alloys have been investigated in the solidification process by means of X-ray diffraction. The results of liquid structure show that there is a break point in the mean nearest neighbor distance r1 and the coordination number Nmin for glass-forming liquid, while the correlation radius rc and the coordination number Nmin display a monotone variational trend above the break point. It means glass-forming liquids have a steady changing in structure above liquidus and more inhomogeneous state at liquidus. We conclude that there is a strong correlation between liquid structure and glass forming ability in Ag-based binary alloys.

  17. Gardnerella vaginalis outcompetes 29 other bacterial species isolated from BV patients in an in vitro biofilm formation model

    OpenAIRE

    Alves, P.; Castro, J.; Sousa, Cármen; Cereija, Tatiana Barros Reis; Cerca, Nuno

    2014-01-01

    Despite the worldwide prevalence of bacterial vaginosis (BV), its etiology is still unknown. Although BV has been associated with the presence of biofilm, the ability of BV-associated bacteria to form biofilms is still largely unknown. Here, we isolated 30 BV-associated species and characterized their virulence, using an in vitro biofilm formation model. Our data suggests that Gardnerella vaginalis had the highest virulence potential, as defined by higher initial adhesion and cytotoxicity of ...

  18. Phenotypic and genotypic characterization of canine pyoderma isolates of Staphylococcus pseudintermedius for biofilm formation

    OpenAIRE

    CASAGRANDE PROIETTI, Patrizia; Stefanetti, Valentina; HYATT, Doreene Rose; MARENZONI, Maria Luisa; Capomaccio, Stefano; Coletti, Mauro; BIETTA, Annalisa; FRANCIOSINI, Maria Pia; Passamonti, Fabrizio

    2015-01-01

    Biofilm-forming ability is increasingly being recognized as an important virulence factor in several Staphylococcus species. This study evaluated the biofilm-forming ability of sixty canine derived clinical isolates of S. pseudintermedius, using three phenotypic methods, microtiter plate test (MtP), Congo red agar method (CRA) and tube adherence test, and the presence and impact of biofilm-associated genes (icaA and icaD). The results showed that icaA and icaD genes were detected concomitantl...

  19. Crude fatty acid extracts of Streptomyces sps inhibits the biofilm forming Streptococcus pyogenes ATCC 19615

    Directory of Open Access Journals (Sweden)

    Rajalakshm Manickam

    2014-01-01

    Full Text Available Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 Crude fatty acid extract of soil Streptomyces sps on the biofilm formation by Streptococcus pyogenes ATCC 19615 was investigated. Totally, 25 Streptomyces sps were isolated identified from the soil samples collected from Nilgiris hill station. All the isolates were subjected to hydrogen peroxide assay, fatty acid extraction and antibiofilm assay. The fatty acid extracts of S8, S9, and S15 inhibited S. pyogenes at MIC 10 µg/ml. The BIC was observed as 84.6% , 96.41%, 80.5% at 50 µg/ml concentration. Streptolysin S assay showed that the crude lipid extracts have the capability of inhibiting the Streptolysin S activity. There were changes in extracellular protein of the pathogen exposed to the S8, S9 and S15 crude fatty acid extracts (50 µg/ml at the range of 100-120 kDa which elucidates that the fatty acid extracts have a significant role in altering the extracellular protein which might be responsible for virulence of the pathogen. /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}

  20. Candida tropicalis Biofilms: Biomass, Metabolic Activity and Secreted Aspartyl Proteinase Production.

    Science.gov (United States)

    Negri, Melyssa; Silva, Sónia; Capoci, Isis Regina Grenier; Azeredo, Joana; Henriques, Mariana

    2016-04-01

    According to epidemiological data, Candida tropicalis has been related to urinary tract infections and haematological malignancy. Several virulence factors seem to be responsible for C. tropicalis infections, for example: their ability to adhere and to form biofilms onto different indwelling medical devices; their capacity to adhere, invade and damage host human tissues due to enzymes production such as proteinases. The main aim of this work was to study the behaviour of C. tropicalis biofilms of different ages (24-120 h) formed in artificial urine (AU) and their ability to express aspartyl proteinase (SAPT) genes. The reference strain C. tropicalis ATCC 750 and two C. tropicalis isolates from urine were used. Biofilms were evaluated in terms of culturable cells by colony-forming units enumeration; total biofilm biomass was evaluated using the crystal violet staining method; metabolic activity was evaluated by XTT assay; and SAPT gene expression was determined by real-time PCR. All strains of C. tropicalis were able to form biofilms in AU, although with differences between strains. Candida tropicalis biofilms showed a decrease in terms of the number of culturable cells from 48 to 72 h. Generally, SAPT3 was highly expressed. C. tropicalis strains assayed were able to form biofilms in the presence of AU although in a strain- and time-dependent way, and SAPT genes are expressed during C. tropicalis biofilm formation. PMID:26572148

  1. Thermodynamic and relative approach to compute glass-forming ability of oxides

    Indian Academy of Sciences (India)

    Nouar Boubata; Abdelmalek Roula; Islam Moussaoui

    2013-06-01

    This study deals with the evaluation of glass-forming ability (GFA) of oxides and is a critical reading of Sun and Rawson thermodynamic approach to quantify this aptitude. Both approaches are adequate but ambiguous regarding the behaviour of some oxides (tendency to amorphization or crystallization). Indeed, ZrO2 and Al2O3 were inappropriately listed by Sun and Rawson to be glassformer oxides while being intermediate ones.We present a non-dimensional approach to value GFA of single oxide by affecting to each one of the coefficients (without measuring units). Obeying to the non-dimensional analysis rules, we introduce a neglected (in all prior thermodynamic models) characteristic: the isobaric heat capacity (p) of oxides, and execute a mathematical treatment of oxides thermodynamic data.We note this coefficient as thermodynamical relative glass-forming ability (ThRGFA) and formulate a model to compute it. Computed values of 2nd, 3rd, 4th and 5th period metal oxides reveal a clear differentiation between them. Indeed, all glass former oxides are characterized by ThRGFA values over 1.709. Moreover, the value intervals confirm the oxides classification into three groups (forming, intermediate and modifier) and sorting of the former ones in distinctive strong and fragile oxides.

  2. Biofilms and the food industry

    Directory of Open Access Journals (Sweden)

    Nathanon Trachoo

    2003-11-01

    Full Text Available In the past, interest in biofilms was limited to research related to water distribution systems, waste water treatment and dental plaques. Biofilm has become a more popular research topic in many other areas in recent years including food safety. Biofilm formation can compromise the sanitation of food surfaces and environmental surfaces by spreading detached organisms to other areas of processing plants. Unfortunately, these detached organisms are not similar to normal microorganisms suspended in an aquatic environment but are more resistant to several stresses or microbial inactivation including some food preservation methods. Microstructures of biofilms as revealed by different types of microscopic techniques showed that biofilms are highly complex and consist of many symbiotic organisms, some of which are human pathogens. This article reviewed the process of biofilm formation, the significance of biofilms on food or food contact surfaces, their ability to protect foodborne pathogens from environmental stresses and recent methods for the study of biofilms on food contact surfaces.

  3. The Assessment of Proteus mirabilis Susceptibility to Ceftazidime and Ciprofloxacin and the Impact of These Antibiotics at Subinhibitory Concentrations on Proteus mirabilis Biofilms

    OpenAIRE

    Joanna Kwiecińska-Piróg; Krzysztof Skowron; Katarzyna Zniszczol; Eugenia Gospodarek

    2013-01-01

    Rods of the Proteus genus are commonly isolated from patients, especially from the urinary tracts of the catheterised patients. The infections associated with biomaterials are crucial therapeutic obstacles, due to the bactericidal resistance of the biofilm. The aim of this study was to assess the susceptibility of P. mirabilis planktonic forms to ciprofloxacin and ceftazidime, the ability to form biofilm, and the impact of chosen sub-MIC concentrations of these antibiotics on biofilm at diffe...

  4. Impact of Actinobacillus pleuropneumoniae biofilm mode of growth on the lipid A structures and stimulation of immune cells.

    Science.gov (United States)

    Hathroubi, Skander; Beaudry, Francis; Provost, Chantale; Martelet, Léa; Segura, Mariela; Gagnon, Carl A; Jacques, Mario

    2016-07-01

    Actinobacillus pleuropneumoniae (APP), the etiologic agent of porcine pleuropneumonia, forms biofilms on biotic and abiotic surfaces. APP biofilms confers resistance to antibiotics. To our knowledge, no studies have examined the role of APP biofilm in immune evasion and infection persistence. This study was undertaken to (i) investigate biofilm-associated LPS modifications occurring during the switch to biofilm mode of growth; and (ii) characterize pro-inflammatory cytokines expression in porcine pulmonary alveolar macrophages (PAMs) and proliferation in porcine PBMCs challenged with planktonic or biofilm APP cells. Extracted lipid A samples from biofilm and planktonic cultures were analyzed by HPLC high-resolution, accurate mass spectrometry. Biofilm cells displayed significant changes in lipid A profiles when compared with their planktonic counterparts. Furthermore, in vitro experiments were conducted to examine the inflammatory response of PAMs exposed to UV-inactivated APP grown in biofilm or in suspension. Relative mRNA expression of pro-inflammatory genes IL1, IL6, IL8 and MCP1 decreased in PAMs when exposed to biofilm cells compared to planktonic cells. Additionally, the biofilm state reduced PBMCs proliferation. Taken together, APP biofilm cells show a weaker ability to stimulate innate immune cells, which could be due, in part, to lipid A structure modifications. PMID:27226465

  5. COMBINED USE OF FOURIER TRANSFORM INFRARED AND RAMAN SPECTROSCOPY TO STUDY PLANKTONIC AND BIOFILM CELLS OF CRONOBACTER SAKAZAKII

    Directory of Open Access Journals (Sweden)

    Garima Sharma

    2014-02-01

    Full Text Available Cronobacter sakazakii is an opportunistic pathogen, which causes necrotizing enterocolitis, bacteriaemia and infant meningitis. It has the ability to form biofilm on food contact surfaces, creating food safety risks. In this work, the phenotypic expression of planktonic and biofilm was studied by Fourier transform infrared (FTIR and Raman spectroscopy. FTIR spectra of the biofilm cells exhibited higher intensity in the absorption bands assigned to polysaccharides, amide I, amide II vibrational mode of ester and carboxylate group. Raman spectra of the biofilm cells showed higher intensity in the absorption band assigned to tyrosine, amide III, carbohydrates, carotenoids, DNA and lipids. Understanding the chemical properties of planktonic and biofilm cells employing the two techniques helped to decipher the differences in the chemical composition between planktonic and biofilm cells. This can promote a better understanding of the persistence, survival and resistance of the biofilm cells.

  6. Cu-based bulk amorphous alloy with larger glass-forming ability and supercooled liquid region

    Energy Technology Data Exchange (ETDEWEB)

    Fu, H.M. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); School of Engineering, University of Queensland, St. Lucia, Qld 4072 (Australia)], E-mail: waterdrophmfu@hotmail.com; Zhang, H.F. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Wang, H. [Faculty of Engineering and Surveying, University of Southern Queensland, Toowoomba, Qld 4350 (Australia); Hu, Z.Q. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)

    2008-06-30

    The glassy rod with a maximum sample thickness of 11 mm and larger supercooled liquid region of 108 K was successfully fabricated when substituting Cu with minor amount of Ag in the Cu-Zr-Al-Gd alloy system. The value of {gamma} reaches a maximum of 0.418 for the Cu{sub 45.5}Zr{sub 45}Al{sub 7}Gd{sub 2}Ag{sub 0.5} bulk metallic glass (BMG) alloy. The high glass-forming ability (GFA) and larger supercooled liquid region are discussed from atomic size, negative mixing heat among constituent elements and thermodynamics.

  7. Glass Forming Ability of Metallic Glasses Evaluated by a New Criterion

    Institute of Scientific and Technical Information of China (English)

    CAO Qing-Ping; LI Jin-Fu; ZHOU Yao-He

    2008-01-01

    The glass-forming ability (GFA) of Cu-Zr binary alloys is evaluated using the existing criteria based on calorimetric parameters, and poor relations are found. Therefore, another parameter Trk defined as Tk/Tl, in which Tk is the Kauzmann temperature and Tl the equilibrium liquidus temperature, is proposed. It exhibits good agreements with the experimental data of the Cu-Zr system and other representative bulk metallic glass formers so long as classifying them into strong or fragile category. It is suggested that kinetic effects are irrelevantly incorporated in the GFA analysis in the previous work.

  8. Comparative efficacy of antibiotics in biofilms eradication formed by ESBL and non ESBL producing micro-organisms

    Directory of Open Access Journals (Sweden)

    Manu Chaudhary

    2012-06-01

    Full Text Available Growth of bacterial cells within a biofilm complicate the treatment of infections. Therefore, in the present study biofilm eradication efficacy of (ceftriaxone and sulbactam plus EDTA; CSE1034 was compared with ceftriaxone alone, ceftriaxone plus EDTA and ceftriaxone plus sulbactam against biofilms of ESBL producing Escherichia coli, Klebsiella pneumoniae and Salmonella typhi. Susceptibility testing of each drug was performed on planktonic and biofilm cells in non ESBL producing and ESBL producing strains according to the recommendations of clinical and laboratory standards institutes guidelines. CSE1034 inhibited the growth of planktonic cells of non ESBL producing strains with minimum inhibitory concentration (MIC from 0.25 to 1.0 μg/ml; the minimum biofilm eradication concentration (MBEC values ranged from 8 to 32 μg/ml where as ESBL producing strains MIC values were 2 to 4 times higher and corresponding MBEC values were higher by 4 to 8 times. When biofilms of ESBL producing organisms were treated with the half MBEC of drugs, CSE1034 decreased 3 log of bacteria present in biofilm when compared with ceftriaxone, ceftriaxone plus EDTA and ceftriaxone plus sulbactam. In conclusion, combination of CSE1034 acts synergistically and reduces the MIC and MBEC values, significantly. One dimensional polyacrlamide gel elctrophoresis of extracellular proteins revealed distinct difference in protein expression of the group treated with CSE1034. Hence, CSE1034 at low concentration showed greater efficacy in the eradication of biofilm as compared to other two drugs and could be one of the best choices to eradicate the biofilm infections caused by these organisms as compared to other drugs.

  9. Pseudomonas aeruginosa biofilm infections

    DEFF Research Database (Denmark)

    Tolker-Nielsen, Tim

    2014-01-01

    Bacteria in natural, industrial and clinical settings predominantly live in biofilms, i.e., sessile structured microbial communities encased in self-produced extracellular matrix material. One of the most important characteristics of microbial biofilms is that the resident bacteria display a...... remarkable increased tolerance toward antimicrobial attack. Biofilms formed by opportunistic pathogenic bacteria are involved in devastating persistent medical device-associated infections, and chronic infections in individuals who are immune-compromised or otherwise impaired in the host defense. Because the...... use of conventional antimicrobial compounds in many cases cannot eradicate biofilms, there is an urgent need to develop alternative measures to combat biofilm infections. The present review is focussed on the important opportunistic pathogen and biofilm model organism Pseudomonas aeruginosa. Initially...

  10. Accuracy of a selection criterion for glass forming ability in the Ni–Nb–Zr system

    International Nuclear Information System (INIS)

    Highlights: • We applied a selection in the Ni–Nb–Zr system to find alloys with high GFA. • We used the thermal parameter γm to evaluate the GFA of alloys. • The correlation between the γm parameter and Rc in the studied system is poor. • The effect of oxygen impurity reduced dramatically the GFA of alloys. • Unknown intermetallic compounds reduced the accuracy of the criterion. - Abstract: Several theories have been developed and applied in metallic systems in order to find the best stoichiometries with high glass forming ability; however there is no universal theory to predict the glass forming ability in metallic systems. Recently a selection criterion was applied in the Zr–Ni–Cu system and it was found some correlation between experimental and theoretical data. This criterion correlates critical cooling rate for glass formation with topological instability of stable crystalline structures; average work function difference and average electron density difference among the constituent elements of the alloy. In the present work, this criterion was applied in the Ni–Nb–Zr system. It was investigated the influence of factors not considered in the calculation and on the accuracy of the criterion, such as unknown intermetallic compounds and oxygen contamination. Bulk amorphous specimens were produced by injection casting. The amorphous nature was analyzed by X-ray diffraction and differential scanning calorimetry; oxygen contamination was quantified by the inert gas fusion method

  11. Combating biofilms

    DEFF Research Database (Denmark)

    Yang, Liang; Liu, Yang; Wu, Hong;

    2012-01-01

    Biofilms are complex microbial communities consisting of microcolonies embedded in a matrix of self-produced polymer substances. Biofilm cells show much greater resistance to environmental challenges including antimicrobial agents than their free-living counterparts. The biofilm mode of life is...... believed to significantly contribute to successful microbial survival in hostile environments. Conventional treatment, disinfection and cleaning strategies do not proficiently deal with biofilm-related problems, such as persistent infections and contamination of food production facilities. In this review......, strategies to control biofilms are discussed, including those of inhibition of microbial attachment, interference of biofilm structure development and differentiation, killing of biofilm cells and induction of biofilm dispersion....

  12. Proteome changes during yeast-like and pseudohyphal growth in the biofilm-forming yeast Pichia fermentans.

    Science.gov (United States)

    Maserti, Biancaelena; Podda, Alessandra; Giorgetti, Lucia; Del Carratore, Renata; Chevret, Didier; Migheli, Quirico

    2015-06-01

    The Pichia fermentans strain DISAABA 726 is a biofilm-forming yeast that has been proposed as biocontrol agent to control brown rot on apple. How ever, when inoculated on peach, strain 726 shows yeast-like to pseudohyphal transition coupled to a pathogenic behaviour. To identify the proteins potentially involved in such transition process, a comparative proteome analysis of P. fermentans 726 developed on peach (filamentous growth) vs apple (yeast-like growth) was carried out using two-dimensional gel electrophoresis coupled with mass spectrometry analysis. The proteome comparison was also performed between the two different cell morphologies induced in a liquid medium amended with urea (yeast-like cells) or methionine (filamentous cells) to exclude fruit tissue impact on the transition. Seventy-three protein spots showed significant variations in abundance (±twofold, p < 0.01, confidence intervals 99 %) between pseudohyphal vs yeast-like morphology produced on fruits. Among them, 30 proteins changed their levels when the two morphologies were developed in liquid medium. The identified proteins belong to several pathways and functions, such as glycolysis, amino acid synthesis, chaperones, and signalling transduction. The possible role of a group of proteins belonging to the carbohydrate pathway in the metabolic re-organisation during P. fermentans dimorphic transition is discussed. PMID:25743163

  13. Effects of Low-Dose Amoxicillin on Staphylococcus aureus USA300 Biofilms.

    Science.gov (United States)

    Mlynek, Kevin D; Callahan, Mary T; Shimkevitch, Anton V; Farmer, Jackson T; Endres, Jennifer L; Marchand, Mélodie; Bayles, Kenneth W; Horswill, Alexander R; Kaplan, Jeffrey B

    2016-05-01

    Previous studies showed that sub-MIC levels of β-lactam antibiotics stimulate biofilm formation in most methicillin-resistant Staphylococcus aureus (MRSA) strains. Here, we investigated this process by measuring the effects of sub-MIC amoxicillin on biofilm formation by the epidemic community-associated MRSA strain USA300. We found that sub-MIC amoxicillin increased the ability of USA300 cells to attach to surfaces and form biofilms under both static and flow conditions. We also found that USA300 biofilms cultured in sub-MIC amoxicillin were thicker, contained more pillar and channel structures, and were less porous than biofilms cultured without antibiotic. Biofilm formation in sub-MIC amoxicillin correlated with the production of extracellular DNA (eDNA). However, eDNA released by amoxicillin-induced cell lysis alone was evidently not sufficient to stimulate biofilm. Sub-MIC levels of two other cell wall-active agents with different mechanisms of action-d-cycloserine and fosfomycin-also stimulated eDNA-dependent biofilm, suggesting that biofilm formation may be a mechanistic adaptation to cell wall stress. Screening a USA300 mariner transposon library for mutants deficient in biofilm formation in sub-MIC amoxicillin identified numerous known mediators of S. aureus β-lactam resistance and biofilm formation, as well as novel genes not previously associated with these phenotypes. Our results link cell wall stress and biofilm formation in MRSA and suggest that eDNA-dependent biofilm formation by strain USA300 in low-dose amoxicillin is an inducible phenotype that can be used to identify novel genes impacting MRSA β-lactam resistance and biofilm formation. PMID:26856828

  14. 同源性金黄色葡萄球菌生物被膜形成能力比较%Biofilm formation ability of homologous Staphylococcus aureus strains : a comparative study

    Institute of Scientific and Technical Information of China (English)

    孔晋亮; 张东伟; 陈一强; 闫萍; 蔡双启; 简丽娟

    2013-01-01

    目的 比较临床分离同源性金黄色葡萄球菌(SAU)的黏附及生物被膜(BF)形成能力差异.方法 刚果红平板法定性能形成BF的菌株;建立SAU的BF体外静置模型,分别于建模第1、3、7天,采用结晶紫染色方法,比较临床分离同源性SAU的黏附及BF形成能力差异.结果 临床分离10株同源性SAU中,刚果红平板法定性可全部形成BF;SAU 17546的黏附及形成早期BF能力最强(P<0.001),而SAU 17422最弱(P<0.001);形成成熟BF能力,仍以SAU 17546最强(P<0.001),但SAU 17642与17546比较,两者极近似(P =0.495);SAU 17422形成BF能力最弱,但是与17431、18541-2、18558、18565、18719等菌株差异无统计学意义.结论 刚果红平板法可定性SAU形成BF菌株,同源性SAU黏附及形成BF的能力存在差异.%OBJECTIVE To compare the adhesion and the abilities of biofilm formation of the homologous clinical isolates of Staphylococcus aureus. METHODS Congo red plate method was used to detect strains The in vitro biofilm model of S. aureus was established, and the crystal violet staining biofilm semi-quantitative method was employed to compare the adhesion and biofilm formation abilities of the homologous S. aureus. RESULTS Totally 10 strains of homologous S. aureus were biofilm formation-positive, which were isolated from the clinic. The ability of adhesion and early biofilm formation of S. aureus 17546 was the strongest (P<0. 001), but S. aureus 17422's was the weakest (P<0. 001). As for the formation ability of the mature biofilm, S. aureus 17546 was the most powerful (P<0. 001), S. aureus 17642 was extremely similar to strain 17546(P=0. 495). the biofilm formation ability of S. aureus 17422 was the weakest, but as compared with S. aureus 17431, S. aureus 18541-2, S. aureus 18558, S. aureus 18565 and S. aureus 18719, the difference was not statistically significant. CONCLUSION Congo red plate method can detect the S. aureus strains of BF formation. All the homologous S

  15. Modern Technologies of Bacterial Biofilm Study

    Directory of Open Access Journals (Sweden)

    Chebotar I.V.

    2013-03-01

    Full Text Available The aim of the investigation was to estimate the availability of new biomedical technologies to identify bacterial biofilms and evaluate them on a staphylococcal biofilm model. Materials and Methods. We studied staphylococcal biofilms by mass spectrometry, laser scanning (confocal microscopy, scanning electron microscopy, enzymatic and oxidative destruction of extracellular biofilm matrix. Results. We demonstrated the capabilities of new biomedical technologies in identification of generic specificity of biofilm-forming staphylococcus, and in detection of the necessary characteristics of staphylococcal biofilm. Mass spectrometry enabled to identify the type of biofilm-forming staphylococcus (Staphylococcus aureus. Microscopic study using laser scanning confocal microscopic technique revealed 3-demensional organization typical of S. aureus biofilms. Scanning electron microscopy enabled to visualize the structures of extracellular S. aureus biofilm matrix. The extracellular matrix of the test biofilm was found to be formed of DNA-protein complexes.

  16. In vitro apatite-forming ability of hydrogels derived from sodium carboxymethylcellulose

    International Nuclear Information System (INIS)

    Hydrogels able to form a bone-like hydroxyapatite (HAp) layer in the body environment are attractive materials as scaffolds for tissue engineering because they show osteoconductivity, i.e. bone-bonding property. In the present study, we synthesized hydrogels from sodium carboxymethylcellulose (sCMC), a water soluble polymer, through modification with a cross-linking agent, either ethylenediamine (EDA) or 3-aminopropyltriethoxysilane (APTES), followed by treatment with an aqueous solution containing calcium chloride aqueous solution. Formation of the bone-like HAp on the hydrogels was evaluated after immersion in a simulated body fluid (SBF). Hydrogels modified with the cross-linking agents EDA or APTES, and treated with 0.1 mol/dm3 of calcium chloride aqueous solution, formed a bone-like HAp layer on their surfaces after immersion in SBF for 3 days. Modification of organic polymers rich in carboxyl groups with APTES and CaCl2 offers a new method to produce biomaterials with greater potential for forming HAp, which provides high affinity to living bone because the incorporation of silanol groups confers the high ability to induce HAp formation.

  17. In vitro apatite-forming ability of hydrogels derived from sodium carboxymethylcellulose

    Energy Technology Data Exchange (ETDEWEB)

    Koh, M-Y; Ohtsuki, C [Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Morita, Y; Miyazaki, T, E-mail: koh.miyoung@h.mbox.nagoya-u.ac.jp [Graduate School of Life Science and System Engineering, Kyusyu Institute of Technology, 2-4, Hibikino, Wakamatsu-ku, Kitakyusyu 808-0196 (Japan)

    2011-10-29

    Hydrogels able to form a bone-like hydroxyapatite (HAp) layer in the body environment are attractive materials as scaffolds for tissue engineering because they show osteoconductivity, i.e. bone-bonding property. In the present study, we synthesized hydrogels from sodium carboxymethylcellulose (sCMC), a water soluble polymer, through modification with a cross-linking agent, either ethylenediamine (EDA) or 3-aminopropyltriethoxysilane (APTES), followed by treatment with an aqueous solution containing calcium chloride aqueous solution. Formation of the bone-like HAp on the hydrogels was evaluated after immersion in a simulated body fluid (SBF). Hydrogels modified with the cross-linking agents EDA or APTES, and treated with 0.1 mol/dm{sup 3} of calcium chloride aqueous solution, formed a bone-like HAp layer on their surfaces after immersion in SBF for 3 days. Modification of organic polymers rich in carboxyl groups with APTES and CaCl{sub 2} offers a new method to produce biomaterials with greater potential for forming HAp, which provides high affinity to living bone because the incorporation of silanol groups confers the high ability to induce HAp formation.

  18. In vitro apatite-forming ability of hydrogels derived from sodium carboxymethylcellulose

    Science.gov (United States)

    Koh, M.-Y.; Morita, Y.; Miyazaki, T.; Ohtsuki, C.

    2011-10-01

    Hydrogels able to form a bone-like hydroxyapatite (HAp) layer in the body environment are attractive materials as scaffolds for tissue engineering because they show osteoconductivity, i.e. bone-bonding property. In the present study, we synthesized hydrogels from sodium carboxymethylcellulose (sCMC), a water soluble polymer, through modification with a cross-linking agent, either ethylenediamine (EDA) or 3-aminopropyltriethoxysilane (APTES), followed by treatment with an aqueous solution containing calcium chloride aqueous solution. Formation of the bone-like HAp on the hydrogels was evaluated after immersion in a simulated body fluid (SBF). Hydrogels modified with the cross-linking agents EDA or APTES, and treated with 0.1 mol/dm3 of calcium chloride aqueous solution, formed a bone-like HAp layer on their surfaces after immersion in SBF for 3 days. Modification of organic polymers rich in carboxyl groups with APTES and CaCl2 offers a new method to produce biomaterials with greater potential for forming HAp, which provides high affinity to living bone because the incorporation of silanol groups confers the high ability to induce HAp formation.

  19. Attachment of Campylobacter jejuni on biofilms from two chicken houses in Thailand

    Directory of Open Access Journals (Sweden)

    Daungjinda, M.

    2007-01-01

    Full Text Available The attachment of C. jejuni on four gram negative biofilms (FBRL-C04, FBRL-B05, FBRL-F01 and FBRL-B06 isolated from two chicken houses were studied. It was found that C. jejuni attached to biofilm of FBRL-F01 at the highest rate (4.4 logCFU/cm2 compared (P<0.05 to FBRL-C04 FBRL-B05 and FBRL-B06 (4.0 4.0 and 4.1 logCFU/cm2, respectively. Coaggregation between C. jejuni and biofilm organisms may indicate the ability of organisms to form biofilm together. Percent coaggregation between C. jejuni and biofilm organisms, FBRL-C04 and FBRL-F01 was 39.14% and 33.70%, respectively, higher (P<0.05 than thatwith FBRL-B05 and FBRL-B06 (-3.38% and 12.87%, respectively. Hydrophobicity of planktonic and biofilm cells of C. jejuni and 4 biofilm producers were measured by the microbial adhesion to hydrocarbon (MATH method using hexadecane. FBRL-B06 showed the highest (P<0.05 hydrophobicity (68.95% indicating more hydrophobic components on its cell surface. Planktonic cells had lower (P<0.05 hydrophobicity than biofilm cells. However, the degree of hydrophobicity of biofilm cells was not related to attachment of C. jejuni on biofilms.

  20. D-amino acids indirectly inhibit biofilm formation in Bacillus subtilis by interfering with protein synthesis.

    Science.gov (United States)

    Leiman, Sara A; May, Janine M; Lebar, Matthew D; Kahne, Daniel; Kolter, Roberto; Losick, Richard

    2013-12-01

    The soil bacterium Bacillus subtilis forms biofilms on surfaces and at air-liquid interfaces. It was previously reported that these biofilms disassemble late in their life cycle and that conditioned medium from late-stage biofilms inhibits biofilm formation. Such medium contained a mixture of D-leucine, D-methionine, D-tryptophan, and D-tyrosine and was reported to inhibit biofilm formation via the incorporation of these D-amino acids into the cell wall. Here, we show that L-amino acids were able to specifically reverse the inhibitory effects of their cognate D-amino acids. We also show that D-amino acids inhibited growth and the expression of biofilm matrix genes at concentrations that inhibit biofilm formation. Finally, we report that the strain routinely used to study biofilm formation has a mutation in the gene (dtd) encoding D-tyrosyl-tRNA deacylase, an enzyme that prevents the misincorporation of D-amino acids into protein in B. subtilis. When we repaired the dtd gene, B. subtilis became resistant to the biofilm-inhibitory effects of D-amino acids without losing the ability to incorporate at least one noncanonical D-amino acid, D-tryptophan, into the peptidoglycan peptide side chain. We conclude that the susceptibility of B. subtilis to the biofilm-inhibitory effects of D-amino acids is largely, if not entirely, due to their toxic effects on protein synthesis. PMID:24097941

  1. Biofilm formation on tympanostomy tubes depends on methicillin-resistant Staphylococcus aureus genetic lineage.

    Science.gov (United States)

    Jotić, Ana; Božić, Dragana D; Milovanović, Jovica; Pavlović, Bojan; Ješić, Snežana; Pelemiš, Mijomir; Novaković, Marko; Ćirković, Ivana

    2016-03-01

    Bacterial biofilm formation has been implicated in the high incidence of persistent otorrhoea after tympanostomy tube insertion. The aim of the study was to investigate whether biofilm formation on tympanostomy tubes depends on the genetic profile of methicillin-resistant Staphylococcus aureus (MRSA) strains. Capacity of biofilm formation on fluoroplastic tympanostomy tubes (TTs) was tested on 30 MRSA strains. Identification and methicillin resistance were confirmed by PCR for nuc and mecA genes. Strains were genotypically characterised (SCCmec, agr and spa typing). Biofilm formation was tested in microtiter plate and on TTs. Tested MRSA strains were classified into SCCmec type I (36.7 %), III (23.3 %), IV (26.7 %) and V (13.3 %), agr type I (50 %), II (36.7 %) and III (13.3 %), and 5 clonal complexes (CCs). All tested MRSA strains showed ability to form biofilm on microtiter plate. Capacity of biofilm formation on TTs was as following: 13.3 % of strains belonged to the category of no biofilm producers, 50 % to the category of weak biofilm producers and 36.7 % to moderate biofilm producers. There was a statistically significant difference between CC, SCCmec and agr types and the category of biofilm production on TTs tubes (p tube otorrhea. PMID:25796207

  2. Xeroderma pigmentosum neurological abnormalities correlate with colony-forming ability after ultraviolet radiation

    International Nuclear Information System (INIS)

    Xeroderma pigmentosum is an autosomal recessive disease in which DNA repair processes are defective. All xeroderma pigmentosum patients develop premature aging of sun exposed skin, and some develop neurological abnormalities due to premature death of nerve cells. Sensitivity to ultraviolet radiation of 24 xeroderma pigmentosum fibroblast strains was studied in vitro by measuring each strain's ability to divide and form colonies after irradiation. The most sensitive strains were derived from patients who had an early onset of neurological abnormalities; less sensitive strains were from patients with a later onset; and the most resistant strains were from patients without neurological abnormalities. The uv sensitivities of strains from each member of a sibling pair with xeroderma pigmentosum were identical, indicating that uv sensitivity of xeroderma pigmentosum strains is determined by the patient's inherited DNA repair defect. The results suggest that effective DNA repair is required to maintain the functional integrity of the human nervous system by preventing premature death of neurons

  3. Glass forming ability of iron based amorphous alloys depending on Mo, Cr and Co content

    International Nuclear Information System (INIS)

    The Fe41Co7Cr15Mo14C15B6Y2 multicomponent Fe-based alloy is known to be one of the best glass formers in iron-based systems and shows a critical casting thickness of 16 mm. The elements constituting the alloy have different influences on the glass forming ability. Therefore, the content of Mo, Cr and Co was systematically changed in the master alloy Fe77-x(Co,Cr,Mo)xC15B6Y2 to investigate how these three elements support the glassy microstructure. It was found that a certain content of Mo, Cr, and Co leads to a microstructure of amorphous matrix and α-Fe precipitates without any carbides.

  4. On the origin of bulk glass forming ability in Cu-Hf, Zr alloys

    Science.gov (United States)

    Ristić, Ramir; Zadro, Krešo; Pajić, Damir; Figueroa, Ignacio A.; Babić, Emil

    2016-04-01

    Understanding the formation of bulk metallic glasses (BMG) in metallic systems and finding a reliable criterion for selection of BMG compositions are among the most important issues in condensed-matter physics and material science. Using the results of magnetic susceptibility measurements performed on both amorphous and crystallized Cu-Hf alloys (30–70 at% Cu) we find a correlation between the difference in magnetic susceptibilities of corresponding glassy and crystalline alloys and the variation in the glass forming ability (GFA) in these alloys. Since the same correlation can be inferred from data for the properties associated with the electronic structure of Cu-Zr alloys, it seems quite general and may apply to other glassy alloys based on early and late transition metals. This correlation is plausible from the free-energy considerations and provides a simple way to select the compositions with high GFA.

  5. A thermodynamic approach towards glass-forming ability of amorphous metallic alloys

    Indian Academy of Sciences (India)

    Sonal R Prajapati; Supriya Kasyap; Arun Pratap

    2015-12-01

    A quantitative measure of the stability of a glass as compared to its corresponding crystalline state can be obtained by calculating the thermodynamic parameters, such as the Gibbs free energy difference (), entropy difference () and the enthalpy difference () between the super-cooled liquid and the corresponding crystalline phase. is known as the driving force of crystallization. The driving force of crystallization () provides very important information about the glass-forming ability (GFA) of metallic glasses (MGs). Lesser the driving force of crystallization more is the GFA. The varies linearly with the critical size (). According to Battezzati and Garonne the parameter ( = (1−(/))/(1−( / ))) in the expression for should be a constant (i.e., 0.8), but its uniqueness is not observed for all MGs. The thermal stability of various alloy compositions is studied by their undercooled liquid region ( = − ). Large implies greater stability against crystallization of the amorphous structure. Other GFA parameters are also calculated and correlated with critical size ().

  6. Biofilm Formation of Listeria monocytogenes on Various Surfaces

    Directory of Open Access Journals (Sweden)

    M Mahdavi

    2007-10-01

    Full Text Available Introduction & Objective: Listeria monocytogenes is considered as a ubiquitous foodborne pathogen which can lead to serious infections, especially in newborns, elderly, pregnant, and immunocompromised people. The organism has been isolated from many foods and may cause meningitis, septicemia and abortion in pregnant women. Also L. monocytogenes forms biofilms on many food contact surface materials and medical devices. Development of biofilms on many surfaces is a potential source of contamination of foods that may lead to spoilage or transmission of foodborne pathogens. Materials & Methods: Biofilm formation of L. monocytogenes (RITCC 1293 serotype 4a was investigated. Hydrophobicity of L. monocytogenes was measured by MATH method. Then biofilm formation of the organism was assessed at 2, 4, 8, 16 and 20 hours on stainless steel (type 304 no 2B, polyethylene and glass by drop plate method. Results: Results indicated that L. monocytogenes with 85% of hydrophobicity formed biofilm on each of three surfaces. Biofilm formation on stainless steel surfaces was significantly more than other surfaces (p<0.05. Conclusion: The ability of biofilm formation of L. monocytogenes on medical devices and food containers is very important as far as hygiene and disease outbreaks are concerned.

  7. Glass-forming ability of Al-Co alloy under rapid annealing

    Science.gov (United States)

    Liu, Chengyan; Wang, Fei; Rao, Fengfei; Hou, Yasen; Wang, Songyou; Sun, Qiang; Jia, Yu

    2013-04-01

    By using molecular dynamics method, transition of Al-Co alloy from liquid to amorphous structure has been investigated theoretically. The structure parameters, pair distribution functions (PDF), bond-angle distribution functions, and Voronoi polyhedra analysis are adopted as indicators of the evolution of clusters in Al-Co alloy during the rapid cooling processes. We found that below transition temperature, the second peak of PDF curves splits into two pronounced subpeaks, while at all temperature the PDF curves gradually converge to unity at large distance. This indicates that the amorphous alloy exhibits local ordering structure and has no long-range ordering. Besides, the bond-angle distribution function predicts that the degrees in the vicinity of 63.4 and 113.4 are dominated in the system during the processes of rapid annealing, which represent that the icosahedral structures are dominant. Together with the cluster structures observed in simulation, Voronoi polyhedra analysis shows that the most popular polyhedron is full icosahedron with the Voronoi index , which is always predominant in bulk metallic glass (MG) formers with excellent glass forming ability. Our studies indicated that doping of cobalt atoms in the Al-based alloy should have a better capacity of forming MG.

  8. Biofilm monitoring using complex permittivity.

    Energy Technology Data Exchange (ETDEWEB)

    Altman, Susan Jeanne; McGrath, Lucas K.; Dolan, Patricia L.; Yelton, William Graham

    2008-10-01

    There is strong interest in the detection and monitoring of bio-fouling. Bio-fouling problems are common in numerous water treatments systems, medical and dental apparatus and food processing equipment. Current bio-fouling control protocols are time consuming and costly. New early detection techniques to monitor bio-forming contaminates are means to enhanced efficiency. Understanding the unique dielectric properties of biofilm development, colony forming bacteria and nutrient background will provide a basis to the effectiveness of controlling or preventing biofilm growth. Dielectric spectroscopy measurements provide values of complex permittivity, {var_epsilon}*, of biofilm formation by applying a weak alternating electric field at various frequencies. The dielectric characteristic of the biofilm, {var_epsilon}{prime}, is the real component of {var_epsilon}* and measures the biofilm's unique ability to store energy. Graphically observed dependencies of {var_epsilon}{prime} to frequency indicate dielectric relaxation or dielectric dispersion behaviors that mark the particular stage of progression during the development of biofilms. In contrast, any frequency dependency of the imaginary component, {var_epsilon}{double_prime} the loss factor, is expressed as dielectric losses from the biofilm due to dipole relaxation. The tangent angle of these two component vectors is the ratio of the imaginary component to the real component, {var_epsilon}{double_prime}/{var_epsilon}{prime} and is referred to as the loss angle tangent (tan {delta}) or dielectric loss. Changes in tan {delta} are characteristic of changes in dielectric losses during various developmental stages of the films. Permittivity scans in the above figure are of biofilm growth from P. Fluorescens (10e7 CFU's at the start). Three trends are apparent from these scans, the first being a small drop in the imaginary permittivity over a 7 hours period, best seen in the Cole-Cole plot (a). The second trend

  9. Biofilm formation of the L. monocytogenes strain 15G01 is influenced by changes in environmental conditions.

    Science.gov (United States)

    Nowak, Jessika; Cruz, Cristina D; Palmer, Jon; Fletcher, Graham C; Flint, Steve

    2015-12-01

    Listeria monocytogenes 15G01, a strain belonging to the persistent pulsotype 5132, was isolated from a seafood processing plant in New Zealand. Simple monoculture assays using crystal violet staining showed good biofilm formation for this strain and it was therefore chosen to be further investigated in regard to its biofilm forming ability. To evaluate its behaviour in different conditions commonly encountered in food processing environments, biofilm assays and growth studies were performed using common laboratory media under a range of temperatures (20 °C, 30 °C and 37 °C). Furthermore, the effects of incubation time and different environmental conditions including static, dynamic and anaerobic incubation on biofilm formation were investigated. Changes in the environmental conditions resulted in different biofilm phenotypes of L. monocytogenes 15G01. We demonstrated that increasing temperature and incubation time led to a higher biofilm mass and that dynamic incubation has little effect on biofilm formation at 37 °C but encourages biofilm formation at 30 °C. Biofilm production at 20 °C was minimal regardless of the medium used. We furthermore observed that anaerobic environment led to reduced biofilm mass at 30 °C for all tested media but not at 37 °C. Biofilm formation could not be narrowed down to one factor but was rather dependent on multiple factors with temperature and medium having the biggest effects. PMID:26524221

  10. Investigating the Effectiveness of Centaureacyanus Extracts on Planktonic Growth and Biofilm Structures of Six Pathogenic Bacteria

    Directory of Open Access Journals (Sweden)

    Z Mohsenipour

    2014-10-01

    Full Text Available Introduction: Nowadays, the treatments of infectious disease are regarded difficult due to increasing antibiotic resistance among pathogenic bacteria, which the reason may be placing of microorganisms in a structure named biofilm. Biofilms are complex structures consisting of surface-attached bacteria. Therefore, it is essential to find new compounds in order to remove and inhibit biofilms. This study aimed to examine the antibacterial activities of alcoholic extracts of Centaurea cyanus on the biofilm structures and planktonic form of six pathogen bacteria(Staphylococcusaureus, Bacilluscereus, Streptococcuspneumoniae, Pseudomonasaeruginosa, Escherichiacoli and Klebsiellapneumonia. Methods: Antimicrobial activities of the alcoholic plant extracts against the planktonic form of bacteria were assessed via using the disc diffusion method. MIC and MBC values were determined by a macrobroth dilution technique and anti-biofilm effects were scrutinized by microtiter plate method. Results: The results of this study confirmed high ability of C.cyanus extracts against the biofilm of the tested bacteria as well as their free-living forms. To inhibit bacterial growth, ethanolic extracts proved to be more effective than methanolic extracts. Anti-biofilm effects of plant extracts were associated with the solvent type and extract concentration. C.cyanus extracts were reported to be most efficient to inhibit biofilm formation of E. coli (84/26% and S. pneumoniae(83/14%. The greatest eradication of biofilm structures were observed on S. pneumonia biofilm (75.66%, and the highest decrease in metabolic activity was reported in S.aureus biofilms (71/85%. Conclusion: In this study the high capacity of C. cyanus extracts to encounter with whit biofilm was emphasized. Moreover, it was demonstrated that these extracts possess an appropriate potential to become active principles of new drugs.

  11. Phenotypic Characterization of Streptococcus pneumoniae Biofilm Development

    OpenAIRE

    Allegrucci, Magee; Hu, F.Z.; Shen, K.; J. Hayes; Ehrlich, Garth D.; Post, J Christopher; Sauer, Karin

    2006-01-01

    Streptococcus pneumoniae is among the most common pathogens associated with chronic otitis media with effusion, which has been hypothesized to be a biofilm disease. S. pneumoniae has been shown to form biofilms, however, little is known about the developmental process, the architecture, and the changes that occur upon biofilm development. In the current study we made use of a continuous-culture biofilm system to characterize biofilm development of 14 different S. pneumoniae strains representi...

  12. Adherence and biofilm production of invasive and non-invasive isolates of Streptococcus pyogenes after hyaluronidase treatment

    Directory of Open Access Journals (Sweden)

    Šmitran Aleksandra

    2013-01-01

    Full Text Available Biofilm represents a protected mode, which allows bacteria to survive and proliferate in a hostile environment. Little is known whether the ability to form biofilms is a characteristic of all groups of A streptococcal (GAS strains and whether there is a relationship between biofilm formation and a clinical source of isolates. A capsule physically covers superficial adhesins and other proteins, essential in bacterial attachment, as the first step in biofilm formation. It is also possible that hyaluronic acid could form part of the complex extracellular polymer matrix of biofilms and contribute to the three-dimensional architecture of the biofilm. The aim of this study was to investigate if there are differences in adherence and biofilm production between GAS strains with different pathogenic potential, and the possible role of the capsule in this process. A total of 122 isolates were divided into three groups: noninvasive (NI, low invasive (LI and highly invasive (HI. Adherence, SpeB and biofilm production were tested before and after hyaluronidase treatment. There was no difference in adherence between untreated GAS strains, but after capsule removal, NI and HI isolates adhered significantly better than the LI group. Before treatment, isolates of the HI group were the worst biofilm producers, but after capsule removal, they became the best biofilm producers. There was no difference in SpeB production among GAS isolates, regardless of the hyaluronidase treatment.

  13. A new parameter to evaluate the glass-forming ability of bulk metallic glasses

    International Nuclear Information System (INIS)

    Research highlights: → Develop a new criterion, i.e., Q=((Tg+Tx)/Tl).(ΔE/ΔH). → The reliability and benefits of the new criterion have been demonstrated in a wide range of BMG alloys. → It corresponds well with the critical diameter of BMGs investigated up to now. - Abstract: Based on the consideration of the liquid phase stability, the resistance to crystallization and the glass transition enthalpy, a new criterion Q, defined as ((Tg + Tx)/Tl).(ΔE/ΔH), where the Tg, Tx, Tl, ΔE and ΔH are the glass transition temperature, the onset crystallization temperature, the liquidus temperature, the crystalline enthalpy and the fusion enthalpy, respectively, has been proposed for evaluating the glass-forming ability of bulk metallic glasses. The new criterion Q exhibits better correlation with the maximum cross section thickness (Dm) for glass formation compared with γ (=Tx/(Tl + Tg)), Trg (=Tg/Tl) and ΔTx (=Tx - Tg) respectively. The available data from literatures and experiments have confirmed the effectiveness of the newly developed criterion.

  14. Fragility and glass forming ability of Al-Ni-Ce alloy melts

    Institute of Scientific and Technical Information of China (English)

    赵岩; 边秀房; 孙民华; 张均艳

    2004-01-01

    The fragility of Al-Ni-Ce alloy melts with three kinds of different compositions, Al85Ni10Ce5,Al85Ni8Ce7, Al85Ni5Ce10(mole fraction, %), was studied using oscillating-vessel viscometer and differential scanning calorimetry. Their fragility parameters obtained from experiments and theoretic calculation are:238,228 and 335 respectively. The results indicate that these three kinds of Al-Ni-Ce alloy melts are very fragile liquids, which kinetically show strong non-Arrhenius behaviour in the Angell plot, so they have poor glass forming ability (GFA).The alloy melt Al85Ni5Ce10 has the largest fragility parameter among the three alloy melts. In the preparation of rapidly quenched amorphous ribbons, Al85Ni10Ce5 and Al85Ni8Ce7 can gain amorphous ribbons when the rotate speed of the roller reaches 800 r/min, while for Al85Ni5Ce10 it must exceed 1 000 r/min.

  15. Glass forming ability, mechanical and magnetic properties in Fe-W-Y-B alloys

    International Nuclear Information System (INIS)

    Glass forming ability (GFA), mechanical and magnetic properties of Fe72WxY6-xB22 (x = 0, 1, 2 and 3 at.%) and Fe72-xWxY6B22 (x 1, 2, 3, 4, 5 and 6 at.%) alloys have been experimentally investigated. It is found that fully amorphous Fe69W3Y6B22 and Fe68W4Y6B22 cylindrical rods with 4 mm in diameter can be prepared by using copper mold casting. The newly developed Fe-based quaternary alloys exhibit excellent combination properties: good GFA, high onset crystallization temperature of 970 K, high fracture strength of about 4 GPa, Vickers hardness of about 1000 kg/mm2, and good soft magnetic properties at ambient temperature (saturation magnetization of about 0.8 T and coercive force of below 2 A/m), which show potential applications in electronic industries. The effect of W addition on GFA in the Fe-Y-B alloy system is discussed.

  16. Influence of Kinetic and Thermodynamic Factors on the Glass-Forming Ability of Zirconium-Based Bulk Amorphous Alloys

    OpenAIRE

    Mukherjee, S.; Schroers, J.; Johnson, W. L.; Rhim, W. K.

    2005-01-01

    The time-temperature-transformation curves for three zirconium-based bulk amorphous alloys are measured to identify the primary factors influencing their glass-forming ability. The melt viscosity is found to have the most pronounced influence on the glass-forming ability compared to other thermodynamic factors. Surprisingly, it is found that the better glass former has a lower crystal-melt interfacial tension. This contradictory finding is explained by the icosahedral short-range order of the...

  17. Potential mode of protection of silkworm pupae from environmental stress by harboring the bacterial biofilm on the surfaces of silk cocoons.

    Science.gov (United States)

    Halder, Pranab K; Naskar, Deboki; Kumar, Akash; Yao, Juming; Kundu, Subhas C; Ghosh, Anindya S

    2015-02-01

    The silkworm forms cocoon to protect its pupa that survives for months inside the cocoon without being affected by various environmental stresses. To understand the possible mode of pupal survival within the cocoon encasement, we investigate the cause that protects the cocoon. During the end of the spinning process, we have isolated different bacterial species from the cocoon surface. These are identified using molecular techniques and checked for their abilities to form biofilm in vitro. The bacteria are able to form biofilm either individually or in consortia. Of which, Bacillus and Erwinia species are prominent biofilm formers. Interestingly, these bacteria have the ability to form biofilm on the cocoon mimetic surface of the silk protein Sericin Hope that contains only sericin. The origin and the behavior of the bacteria lead us to hypothesize the possible role of biofilm layer on the cocoon surface, which provides protection from adverse environmental conditions. PMID:25292249

  18. Post-UV colony-forming ability of normal fibroblast strains and of the xeroderma pigmentosum group G strain

    International Nuclear Information System (INIS)

    In xeroderma pigmentosum, an inherited disorder of defective DNA repair, post-uv colony-forming ability of fibroblasts from patients in complementation groups A through F correlates with the patients' neurological status. The first xeroderma pigmentosum patient assigned to the recently discovered group G had the neurological abnormalities of XP. Researchers have determined the post-uv colony-forming ability of cultured fibroblasts from this patient and from 5 more control donors. Log-phase fibroblasts were irradiated with 254 nm uv light from a germicidal lamp, trypsinized, and replated at known densities. After 2 to 4 weeks' incubation the cells were fixed, stained and scored for colony formation. The strains' post-uv colony-forming ability curves were obtained by plotting the log of the percent remaining post-uv colony-forming ability as a function of the uv dose. The post-uv colony-forming ability of 2 of the 5 new normal strains was in the previously defined control donor zone, but that of the other 3 extended down to the level of the most resistant xeroderma pigmentosum strain. The post-uv colony-forming ability curve of the group G fibroblasts was not significantly different from the curves of the group D fibroblast strains from patients with clinical histories similar to that of the group G patient

  19. Moderate Hypoxia Exhibits Increased Endothelial Progenitor Vessel-forming Ability However Gestational Diabetes Caused to Impede Compensatory Defense Reaction

    Science.gov (United States)

    Dincer, U. Deniz

    2016-01-01

    Endothelium represents a defense barrier and responds and integrates neuro humoral stimulus which describes as a compensatory mechanism. Endothelium formed with endothelial cells (ECs) and their progenitors. Endothelial progenitor cells (EPCs) represent minor subpopulation of mononuclear cells in the blood. During acute hypoxia, larger amount of EPCs mobilize into the peripheral blood and they directly contribute revascularization process. One of the subtypes of EPC is termed endothelial colony forming cells (ECFCs) which they possess de novo vessel-forming ability. The present study aims to investigate the role of hypoxia in EPCs functional and vessel-forming ability. Furthermore, it was investigated whether fetal exposure to a diabetic intrauterine environment influence EPCs adaptation ability. Human umbilical cord blood (HUCB) derived ECFCs were selected in all experimental procedures obtained from normal and gestational diabetes mellitus (GDM) subjects via in vitro cell culture methods. Early passage (hypoxia associated gene specific primers designed to perform Real-time PCR. Senescenes assay conducted onto HUCB ECFCs to investigate their functional clonogenic ability. To quantify their vessel forming ability matrigel assay was applied. These data demonstrates that moderate hypoxia results increased vessel-forming ability and VEGFA expression in HUCB ECFCs obtained from control subjects. However, GDM caused to impede compensatory defense reaction against hypoxia which observed in control subjects. Thus, it illuminates beneficial information related future therapeutic modalities. PMID:27426097

  20. About forming of personality physical culture of students in the process of physical education (in aspect of presence of abilities)

    OpenAIRE

    Belykh S.I.; Chernigovskaia S.A.

    2013-01-01

    It is shown that practice of teaching of discipline «Physical education» does not provide forming of volume of abilities, sufficient for the origin of athletic activity. Prevail ability to pick up a place, sporting form, inventory depending on the type of physical exercises and ability on the observance of rules of the personal hygiene. In the questionnaire questioning 650 students (324 youths and 326 girls of the first and fourth courses) took part. All of students visited employments on phy...

  1. Novel Targets for Treatment of Pseudomonas aeruginosa Biofilms

    DEFF Research Database (Denmark)

    Alhede, Morten; Alhede, Maria; Bjarnsholt, Thomas

    2014-01-01

    Pseudomonas aeruginosa causes infection in all parts of the human body. The bacterium is naturally resistant to a wide range of antibiotics. In addition to resistance mechanisms such as efflux pumps, the ability to form aggregates, known as biofilm, further reduces Pseudomonas aeruginosa...

  2. Iron and Acinetobacter baumannii Biofilm Formation

    OpenAIRE

    Valentina Gentile; Emanuela Frangipani; Carlo Bonchi; Fabrizia Minandri; Federica Runci; Paolo Visca

    2014-01-01

    Acinetobacter baumannii is an emerging nosocomial pathogen, responsible for infection outbreaks worldwide. The pathogenicity of this bacterium is mainly due to its multidrug-resistance and ability to form biofilm on abiotic surfaces, which facilitate long-term persistence in the hospital setting. Given the crucial role of iron in A. baumannii nutrition and pathogenicity, iron metabolism has been considered as a possible target for chelation-based antibacterial chemotherapy. In this study, w...

  3. Quantitative Evaluation of Bacteria Adherent and in Biofilm on Single-Wall Carbon Nanotube-Coated Surfaces

    Directory of Open Access Journals (Sweden)

    Fabrizio Pantanella

    2011-01-01

    Full Text Available Biofilm is a common bacterial lifestyle, and it plays a crucial role in human health, causing biofilm-mediated infections. Recently, to counteract biofilm development, new nano-structured biomaterials have been proposed. However, data about the antibacterial properties of nano-structured surfaces are fragmentary and controversial, and, in particular, the susceptibility of nano-structured materials to colonization and biofilm formation by bacterial pathogens has not been yet thoroughly considered. Here, the ability of the pathogenic Streptococcus mutans and Pseudomonas aeruginosa to adhere and form biofilm on surfaces coated with single-wall carbon nanotubes (SWCNTs was analyzed. Our results showed that the surfaces of SWCNTs-coated glass beads (SWCNTs-GBs were colonized at the same extent of uncoated GBs both by S. mutans and P. aeruginosa. In conclusion, our results demonstrate that single wall SWCNTs-coated surfaces are not suitable to counteract bacterial adhesion and biofilm development.

  4. Proteus mirabilis biofilm - Qualitative and quantitative colorimetric methods-based evaluation

    Directory of Open Access Journals (Sweden)

    Joanna Kwiecinska-Piróg

    2014-12-01

    Full Text Available Proteus mirabilis strains ability to form biofilm is a current topic of a number of research worldwide. In this study the biofilm formation of P. mirabilis strains derived from urine of the catheterized and non-catheterized patients has been investigated. A total number of 39 P. mirabilis strains isolated from the urine samples of the patients of dr Antoni Jurasz University Hospital No. 1 in Bydgoszcz clinics between 2011 and 2012 was used. Biofilm formation was evaluated using two independent quantitative and qualitative methods with TTC (2,3,5-triphenyl-tetrazolium chloride and CV (crystal violet application. The obtained results confirmed biofilm formation by all the examined strains, except quantitative method with TTC, in which 7.7% of the strains did not have this ability. It was shown that P. mirabilis rods have the ability to form biofilm on the surfaces of both biomaterials applied, polystyrene and polyvinyl chloride (Nelaton catheters. The differences in ability to form biofilm observed between P. mirabilis strains derived from the urine of the catheterized and non-catheterized patients were not statistically significant.

  5. Multi-species biofilm of Candida albicans and non-Candida albicans Candida species on acrylic substrate

    Directory of Open Access Journals (Sweden)

    Apurva K Pathak

    2012-02-01

    Full Text Available OBJECTIVE: In polymicrobial biofilms bacteria extensively interact with Candida species, but the interaction among the different species of the Candida is yet to be completely evaluated. In the present study, the difference in biofilm formation ability of clinical isolates of four species of Candida in both single-species and multi-species combinations on the surface of dental acrylic resin strips was evaluated. MATERIAL AND METHODS: The species of Candida, isolated from multiple species oral candidiasis of the neutropenic patients, were used for the experiment. Organisms were cultured on Sabouraud dextrose broth with 8% glucose (SDB. Biofilm production on the acrylic resins strips was determined by crystal violet assay. Student's t-test and ANOVA were used to compare in vitro biofilm formation for the individual species of Candida and its different multi-species combinations. RESULTS: In the present study, differences between the mean values of the biofilm-forming ability of individual species (C. glabrata>C. krusei>C. tropicalis>C. albicans and in its multi-species' combinations (the highest for C. albicans with C. glabrata and the lowest for all the four species combination were reported. CONCLUSIONS: The findings of this study showed that biofilm-forming ability was found greater for non-Candida albicans Candida species (NCAC than for C. albicans species with intra-species variation. Presence of C. albicans in multi-species biofilms increased, whereas; C. tropicalis decreased the biofilm production with all other NCAC species.

  6. The differences in the isoelectric points of biofilm-positive and biofilm-negative Candida parapsilosis strains.

    Science.gov (United States)

    Ruzicka, Filip; Horka, Marie; Hola, Veronika; Kubesova, Anna; Pavlik, Tomas; Votava, Miroslav

    2010-03-01

    The isoelectric points of 39 Candida parapsilosis strains were determined by means of capillary isoelectric focusing. The value of the isoelectric point corresponded well with cell surface hydrophobicity, as well as with the ability to form biofilm in these yeasts. PMID:20079385

  7. Hippocampal Pathway Plasticity Is Associated with the Ability to Form Novel Memories in Older Adults.

    Science.gov (United States)

    Antonenko, Daria; Külzow, Nadine; Cesarz, Magda E; Schindler, Kristina; Grittner, Ulrike; Flöel, Agnes

    2016-01-01

    White matter deterioration in the aging human brain contributes to cognitive decline. The fornix as main efferent hippocampal pathway is one of the tracts most strongly associated with age-related memory impairment. Its deterioration may predict conversion to Alzheimer's dementia and its precursors. However, the associations between the ability to form novel memories, fornix microstructure and plasticity in response to training have never been tested. In the present study, 25 healthy older adults (15 women; mean age (SD): 69 (6) years) underwent an object-location training on three consecutive days. Behavioral outcome measures comprised recall performance on the training days, and on 1-day and 1-month follow up assessments. MRI at 3 Tesla was assessed before and after training. Fornix microstructure was determined by fractional anisotropy and mean diffusivity (MD) values from diffusion tensor imaging (DTI). In addition, hippocampal volumes were extracted from high-resolution images; individual hippocampal masks were further aligned to DTI images to determine hippocampal microstructure. Using linear mixed model analysis, we found that the change in fornix FA from pre- to post-training assessment was significantly associated with training success. Neither baseline fornix microstructure nor hippocampal microstructure or volume changes were significantly associated with performance. Further, models including control task performance (auditory verbal learning) and control white matter tract microstructure (uncinate fasciculus and parahippocampal cingulum) did not yield significant associations. Our results confirm that hippocampal pathways respond to short-term cognitive training, and extend previous findings by demonstrating that the magnitude of training-induced structural changes is associated with behavioral success in older adults. This suggests that the amount of fornix plasticity may not only be behaviorally relevant, but also a potential sensitive biomarker for

  8. Novel bioactive Fe-based metallic glasses with excellent apatite-forming ability.

    Science.gov (United States)

    Qin, Chunling; Hu, Qingfeng; Li, Yongyan; Wang, Zhifeng; Zhao, Weimin; Louzguine-Luzgin, Dmitri V; Inoue, Akihisa

    2016-12-01

    We demonstrate, for the first time, that the (Fe0.75B0.15Si0.1)100-xNbx (x=0, 1 and 3at.%) metallic glasses without toxic and allergic elements exhibit excellent apatite-forming ability in simulated body fluids (SBF), which is expected to be a new generation of biomaterials in stents and orthopedic implants. For the alloys without any surface treatment, spherical particles corresponding to octacalcium phosphate are spontaneously nucleated and precipitated throughout the alloy surface after immersion only for 1day, indicating that the present alloys possess an unusual high bioactivity. During the subsequent in-vitro immersion for 3days, SEM image reveals the typical 'cauliflower' morphology of bone-like hydroxyapatite (HA) with Ca/P ratio of 1.65. In addition, it is surprising to find that the in-vitro SBF immersion not only leads to the formation and growth of the apatite layer but also causes the progressive development of the underlying alloy substrate. Moreover, for the alloys immersed for 3 or 9days, the substrate alloy just beneath the apatite layer consists of a hierarchical nano/macro-porous structure through selective dissolution of the active components Fe and B in the surface. XPS analysis indicates that the apatite nucleation on the present alloys in SBF is attributed to the specific dissolution properties of the present alloys and the fast formation of Si-OH and Fe-OH or Nb-OH functional groups, followed by combination of these groups with Ca(2+) and phosphate ions. PMID:27612742

  9. Effect of carbon on whole-biofilm metabolic response to high doses of streptomycin.

    Science.gov (United States)

    Jackson, Lindsay M D; Kroukamp, Otini; Wolfaardt, Gideon M

    2015-01-01

    Biofilms typically exist as complex communities comprising multiple species with the ability to adapt to a variety of harsh conditions. In clinical settings, antibiotic treatments based on planktonic susceptibility tests are often ineffective against biofilm infections. Using a CO2 evolution measurement system we delineated the real-time metabolic response in continuous flow biofilms to streptomycin doses much greater than their planktonic susceptibilities. Stable biofilms from a multispecies culture (containing mainly Pseudomonas aeruginosa and Stenotrophomonas maltophilia), Gram-negative environmental isolates, and biofilms formed by pure culture P. aeruginosa strains PAO1 and PAO1 ΔMexXY (minimum planktonic inhibitory concentrations between 1.5 and 3.5 mg/l), were exposed in separate experiments to 4000 mg/l streptomycin for 4 h after which growth medium resumed. In complex medium, early steady state multispecies biofilms were susceptible to streptomycin exposure, inferred by a cessation of CO2 production. However, multispecies biofilms survived high dose exposures when there was extra carbon in the antibiotic medium, or when they were grown in defined citrate medium. The environmental isolates and PAO1 biofilms showed similar metabolic profiles in response to streptomycin; ceasing CO2 production after initial exposure, with CO2 levels dropping toward baseline levels prior to recovery back to steady state levels, while subsequent antibiotic exposure elicited increased CO2 output. Monitoring biofilm metabolic response in real-time allowed exploration of conditions resulting in vulnerability after antibiotic exposure compared to the resistance displayed following subsequent exposures. PMID:26441887

  10. Validation of an Adapted French Form of the Career Adapt-Abilities Scale in Four Francophone Countries

    Science.gov (United States)

    Johnston, Claire S.; Broonen, Jean-Paul; Stauffer, Sarah D.; Hamtiaux, Armanda; Pouyaud, Jacques; Zecca, Gregory; Houssemand, Claude; Rossier, Jerome

    2013-01-01

    This study presents the validation of a French version of the Career Adapt-Abilities Scale in four Francophone countries. The aim was to re-analyze the item selection and then compare this newly developed French-language form with the international form 2.0. Exploratory factor analysis was used as a tool for item selection, and confirmatory factor…

  11. Crystallization behavior of Fe- and Co-based bulk metallic glasses and their glass-forming ability

    International Nuclear Information System (INIS)

    In the present work we study and compare the crystallization behavior of Fe- and Co-based good bulk glass formers with an exceptionally high glass-forming ability leading to the critical thickness of cast samples reaching 1 cm. For Fe-based alloys we also investigate the effect of opposite C/B content ratio on the glass-forming ability and the crystallization behavior. The structure and phase composition of the glassy samples were examined by conventional X-ray diffractometry and transmission electron microscopy while thermal stability and phase transformations were studied by differential scanning calorimetry. The reasons for high glass-forming ability are discussed. The glass-forming ability of the studied alloys depends on both factors: the type of crystallization reaction and characteristic temperatures. - Highlights: • Crystallization of Fe-based and Co-based bulk glass-forming alloys. • The reasons for enhanced glass-forming ability of these alloys are discussed. • Low growth rate of χ-Fe36Cr12Mo10 phase. • Reduced liquidus temperature of Fe48Cr15Mo14C6B15RE2 alloys

  12. Biofilm Formation by Cryptococcus neoformans.

    Science.gov (United States)

    Martinez, Luis R; Casadevall, Arturo

    2015-06-01

    The fungus Cryptococcus neoformans possesses a polysaccharide capsule and can form biofilms on medical devices. The increasing use of ventriculoperitoneal shunts to manage intracranial hypertension associated with cryptococcal meningoencephalitis highlights the importance of investigating the biofilm-forming properties of this organism. Like other microbe-forming biofilms, C. neoformans biofilms are resistant to antimicrobial agents and host defense mechanisms, causing significant morbidity and mortality. This chapter discusses the recent advances in the understanding of cryptococcal biofilms, including the role of its polysaccharide capsule in adherence, gene expression, and quorum sensing in biofilm formation. We describe novel strategies for the prevention or eradication of cryptococcal colonization of medical prosthetic devices. Finally, we provide fresh thoughts on the diverse but interesting directions of research in this field that may result in new insights into C. neoformans biology. PMID:26185073

  13. Factors contributing to the biofilm-deficient phenotype of Staphylococcus aureus sarA mutants.

    Directory of Open Access Journals (Sweden)

    Laura H Tsang

    Full Text Available Mutation of sarA in Staphylococcus aureus results in a reduced capacity to form a biofilm, but the mechanistic basis for this remains unknown. Previous transcriptional profiling experiments identified a number of genes that are differentially expressed both in a biofilm and in a sarA mutant. This included genes involved in acid tolerance and the production of nucleolytic and proteolytic exoenzymes. Based on this we generated mutations in alsSD, nuc and sspA in the S. aureus clinical isolate UAMS-1 and its isogenic sarA mutant and assessed the impact on biofilm formation. Because expression of alsSD was increased in a biofilm but decreased in a sarA mutant, we also generated a plasmid construct that allowed expression of alsSD in a sarA mutant. Mutation of alsSD limited biofilm formation, but not to the degree observed with the corresponding sarA mutant, and restoration of alsSD expression did not restore the ability to form a biofilm. In contrast, concomitant mutation of sarA and nuc significantly enhanced biofilm formation by comparison to the sarA mutant. Although mutation of sspA had no significant impact on the ability of a sarA mutant to form a biofilm, a combination of protease inhibitors (E-64, 1-10-phenanthroline, and dichloroisocoumarin that was shown to inhibit the production of multiple extracellular proteases without inhibiting growth was also shown to enhance the ability of a sarA mutant to form a biofilm. This effect was evident only when all three inhibitors were used concurrently. This suggests that the reduced capacity of a sarA mutant to form a biofilm involves extracellular proteases of all three classes (serine, cysteine and metalloproteases. Inclusion of protease inhibitors also enhanced biofilm formation in a sarA/nuc mutant, with the combined effect of mutating nuc and adding protease inhibitors resulting in a level of biofilm formation with the sarA mutant that approached that of the UAMS-1 parent strain. These results

  14. Biofilm in endodontics: A review

    Science.gov (United States)

    Jhajharia, Kapil; Parolia, Abhishek; Shetty, K Vikram; Mehta, Lata Kiran

    2015-01-01

    Endodontic disease is a biofilm-mediated infection, and primary aim in the management of endodontic disease is the elimination of bacterial biofilm from the root canal system. The most common endodontic infection is caused by the surface-associated growth of microorganisms. It is important to apply the biofilm concept to endodontic microbiology to understand the pathogenic potential of the root canal microbiota as well as to form the basis for new approaches for disinfection. It is foremost to understand how the biofilm formed by root canal bacteria resists endodontic treatment measures. Bacterial etiology has been confirmed for common oral diseases such as caries and periodontal and endodontic infections. Bacteria causing these diseases are organized in biofilm structures, which are complex microbial communities composed of a great variety of bacteria with different ecological requirements and pathogenic potential. The biofilm community not only gives bacteria effective protection against the host's defense system but also makes them more resistant to a variety of disinfecting agents used as oral hygiene products or in the treatment of infections. Successful treatment of these diseases depends on biofilm removal as well as effective killing of biofilm bacteria. So, the fundamental to maintain oral health and prevent dental caries, gingivitis, and periodontitis is to control the oral biofilms. From these aspects, the formation of biofilms carries particular clinical significance because not only host defense mechanisms but also therapeutic efforts including chemical and mechanical antimicrobial treatment measures have the most difficult task of dealing with organisms that are gathered in a biofilm. The aim of this article was to review the mechanisms of biofilms’ formation, their roles in pulpal and periapical pathosis, the different types of biofilms, the factors influencing biofilm formation, the mechanisms of their antimicrobial resistance, techniques to

  15. Permeabilizing biofilms

    Science.gov (United States)

    Soukos, Nikolaos S.; Lee, Shun; Doukas, Apostolos G.

    2008-02-19

    Methods for permeabilizing biofilms using stress waves are described. The methods involve applying one or more stress waves to a biofilm, e.g., on a surface of a device or food item, or on a tissue surface in a patient, and then inducing stress waves to create transient increases in the permeability of the biofilm. The increased permeability facilitates delivery of compounds, such as antimicrobial or therapeutic agents into and through the biofilm.

  16. Role of swarming in the formation of crystalline Proteus mirabilis biofilms on urinary catheters.

    Science.gov (United States)

    Jones, Brian V; Mahenthiralingam, E; Sabbuba, N A; Stickler, D J

    2005-09-01

    The care of many patients undergoing long-term bladder catheterization is frequently complicated by infection with Proteus mirabilis. These organisms colonize the catheter, forming surface biofilm communities, and their urease activity generates alkaline conditions under which crystals of magnesium ammonium phosphate and calcium phosphate are formed and become trapped in the biofilm. As the biofilm develops it obstructs the flow of urine through the catheter, causing either incontinence due to leakage of urine around the catheter or retention of urine in the bladder. The aim of this study was to investigate the role of the surface-associated swarming motility of P. mirabilis in the initiation and development of these crystalline catheter biofilms. A set of stable transposon mutants with a range of swimming and swarming abilities were tested for their ability to colonize silicone surfaces in a parallel-plate flow cell. A laboratory model of the catheterized bladder was then used to examine their ability to form crystalline, catheter-blocking biofilms. The results showed that neither swarming nor swimming motility was required for the attachment of P. mirabilis to silicone. Mutants deficient in swarming and swimming were also capable of forming crystalline biofilms and blocking catheters more rapidly than the wild-type strain. PMID:16091430

  17. Sensitivity of planktonic and biofilm-associated Aeromonas spp. to ionizing radiation

    International Nuclear Information System (INIS)

    Genus Aeromonas has emerged as an important human pathogen because it causes a variety of diseases including gastroenteritis and extra-intestinal infections. Aeromonas have the ability to adhere and form biofilms on food surfaces and food contact surfaces. Biofilm formation on foods and food contact surfaces is the major reason for contamination, cross contamination and post-processing contamination of the final food product leading to food spoilage, product rejection, economic losses and food-borne diseases. Biofilms have shown high resistance to heat, desiccation, acidic condition, high salt concentration, antibiotics and other food preservatives. Earlier studies in our laboratory have shown that ionizing radiation effectively inactivates Aeromonas in different food products. However, the relative efficacy of this process against biofilm associated cells versus free-living planktonic cells of Aeromonas is not well documented. Therefore, the dose of gamma radiation required to reduce the population by 90% (D10) was calculated for planktonic and biofilm-associated A. salmonicida Y567 and A. hydrophila A331 cells. Both A. hydrophila A331 and A. salmonicida Y567 expressed significant ability to attach and grow on glass surface following incubation at 30℃ in TSB. Ionizing radiation effectively reduced the populations of both planktonic and biofilm-associated cells for both the strains. Mean cell counts of survivors and surviving fraction of planktonic and biofilm-associated cells decreased with increased irradiation doses. The D10 values of planktonic cells and biofilm cells for A. salmonicida (Y567) were 232.65 Gy and 248.41 Gy, respectively; whereas, the D10 values of planktonic cells and biofilm cells for A. hydrophila (A331) were 249.2 Gy and 240.2 Gy respectively. No significant difference in the D10 values of planktonic and biofilm associated Aeromonas was observed. The influence of the cultured state of the organism, i.e., planktonic versus biofilm associated

  18. Roles of curli, cellulose and BapA in Salmonella biofilm morphology studied by atomic force microscopy

    Directory of Open Access Journals (Sweden)

    Kader Abdul

    2007-07-01

    Full Text Available Abstract Background Curli, cellulose and the cell surface protein BapA are matrix components in Salmonella biofilms. In this study we have investigated the roles of these components for the morphology of bacteria grown as colonies on agar plates and within a biofilm on submerged mica surfaces by applying atomic force microscopy (AFM and light microscopy. Results AFM imaging was performed on colonies of Salmonella Typhimurium grown on agar plates for 24 h and on biofilms grown for 4, 8, 16 or 24 h on mica slides submerged in standing cultures. Our data show that in the wild type curli were visible as extracellular material on and between the cells and as fimbrial structures at the edges of biofilms grown for 16 h and 24 h. In contrast to the wild type, which formed a three-dimensional biofilm within 24 h, a curli mutant and a strain mutated in the global regulator CsgD were severely impaired in biofilm formation. A mutant in cellulose production retained some capability to form cell aggregates, but not a confluent biofilm. Extracellular matrix was observed in this mutant to almost the same extent as in the wild type. Overexpression of CsgD led to a much thicker and a more rapidly growing biofilm. Disruption of BapA altered neither colony and biofilm morphology nor the ability to form a biofilm within 24 h on the submerged surfaces. Besides curli, the expression of flagella and pili as well as changes in cell shape and cell size could be monitored in the growing biofilms. Conclusion Our work demonstrates that atomic force microscopy can efficiently be used as a tool to monitor the morphology of bacteria grown as colonies on agar plates or within biofilms formed in a liquid at high resolution.

  19. Multidrug Resistance Related to Biofilm Formation in Acinetobacter baumannii and Klebsiella pneumoniae Clinical Strains from Different Pulsotypes.

    Science.gov (United States)

    de Campos, Paola Amaral; Royer, Sabrina; da Fonseca Batistão, Deivid William; Araújo, Bruna Fuga; Queiroz, Lícia Ludendorff; de Brito, Cristiane Silveira; Gontijo-Filho, Paulo P; Ribas, Rosineide Marques

    2016-05-01

    The emergence of Acinetobacter baumannii and Klebsiella pneumoniae strains in the hospital environment has been associated with the presence of multiple genetic elements, virulence factors and the ability to form biofilms. This study evaluated the biofilm formation ability of clinical and environmental A. baumannii and K. pneumoniae strains, isolated from various sources and presenting different molecular characteristics, resistance profiles and pulsed-field gel electrophoresis patterns. Fifty-three isolates were recovered from 2009 to 2014 in a Brazilian university hospital. Investigation of biofilm formation was performed for 10 strains of each species assessed by an initial adhesion assay, biofilm cell concentration and biofilm biomass, evaluated by quantitative assays in replicates, in three independent experiments. All strains of A. baumannii were able to attach to polystyrene plates, although two strains adhered to a lesser degree than the control. K. pneumoniae strains showed opposite behaviour, where only three strains adhered significantly when compared to the control. Quantitative evaluation revealed that in five A. baumannii and four K. pneumoniae isolates the biomass production could be characterised as moderate. None of the isolates were strong biofilm producers. Our results demonstrate: (1) biofilm formation is a heterogeneous property amongst A. baumannii and K. pneumoniae clinical strains and it was not associated with certain clonal types; (2) no relationship between multidrug resistance and biofilm production was observed; (3) more virulent K. pneumoniae strains tended to present higher production of biofilm. PMID:26846651

  20. Bacterial biofilms with emphasis on coagulase-negative staphylococci

    Directory of Open Access Journals (Sweden)

    A Oliveira

    2008-01-01

    Full Text Available In addition to their capacity to attach to surfaces, various groups of microorganisms also produce an extracellular polymeric substance known as "slime". This slime forms a thin layer around cells known as biofilm. Thus, biofilm structure comprises bacterial cells and an extracellular polymeric substance. It also presents a defined architecture, providing the microorganisms with an excellent protective environment and favoring the exchange of genetic material between cells as well as intercellular communication. The ability to produce biofilm is observed in a large group of bacteria, including coagulase-negative staphylococci (CNS which are the predominant microorganisms of normal skin flora and have been implicated as the causative agents of hospital infections. Bacteremia caused by these agents is common in immunodepressed persons, in patients with cancer, in adult and neonatal intensive care units (ICU and in patients using catheters or other prosthetic devices. The pathogenicity of CNS infections is probably related to the production of slime, which adheres preferentially to plastic and smooth surfaces, forming a biofilm that protects against attacks from the immune system and against antibiotic treatment, a fact hindering the eradication of these infections. The main objective of the present review was to describe basic and genetic aspects of biofilm formation and methods for its detection, with emphasis on biofilm creation by CNS and its relationship with diseases caused by these microorganisms which are becoming increasingly more frequent in the hospital environment.

  1. Biofilms: a developing microscopic community

    Directory of Open Access Journals (Sweden)

    Rivera Sandra Patricia

    2004-09-01

    Full Text Available Biofilms are microbial communities composed by different microbiota embebbed in a special adaptive environment. These communities show different characteristics such as heterogeneity, diversity in microenvironments, capacity to resist antimicrobial therapy and ability to allow bacterial communication. These characteristics convert them in complex organizations that are difficult to eradicate in their own environment. In the man, biofilms are associated to a great number of slow-development infectious processes which greatly difficulties their eradication. In the industry and environment, biofilms are centered in processes known as biofouling and bioremediation. The former is the contamination of a system due to the microbial activity of a biofilm. The latter uses biofilms to improve the conditions of a contaminated system. The study of biofilms is a new and exciting field which is constantly evolving and whose implications in medicine and industry would have important repercussions for the humankind.

  2. Virulence aspects of Staphylococcus epidermidis : biofilm formations and Poly-N-Acetyl-Glucosamine production

    OpenAIRE

    Cerca, Nuno

    2006-01-01

    Tese Doutoramento em Engenharia Química e Biológica Staphylococcus epidermidis and other Staphylococci are now well established as major nosocomial pathogens associated with infections of indwelling medical devices. The major virulence factor of these organisms is their ability to adhere to devices and form biofilms. Biofilms are complex microbial communities wherein bacteria acquire different characteristics from their planktonic counterparts, like enhanced resistance to antibiotics and h...

  3. Effect of growth in biofilms upon antibiotic and chlorine susceptibility of Mycobacterium avium and Mycobacterium intracellulare

    OpenAIRE

    Steed, Keesha

    2003-01-01

    ABSTRACT Mycobacterium avium and Mycobacterium intracellulare are environmental opportunistic pathogens whose source for human infection is water and soil. M. avium and M. intracellulare cause pulmonary infections (tuberculosis) in immunocompetent individuals and bacteremia in immunodeficient individuals (e.g. AIDS). One factor likely influencing the lack of success of antibiotic therapy in patients would be their ability to form biofilms. Growth in biofilms might result in antimicrob...

  4. Phenazine-1-Carboxylic Acid Promotes Bacterial Biofilm Development via Ferrous Iron Acquisition▿†

    OpenAIRE

    Wang, Yun; Wilks, Jessica C.; Danhorn, Thomas; Ramos, Itzel; Croal, Laura; Newman, Dianne K.

    2011-01-01

    The opportunistic pathogen Pseudomonas aeruginosa forms biofilms, which render it more resistant to antimicrobial agents. Levels of iron in excess of what is required for planktonic growth have been shown to promote biofilm formation, and therapies that interfere with ferric iron [Fe(III)] uptake combined with antibiotics may help treat P. aeruginosa infections. However, use of these therapies presumes that iron is in the Fe(III) state in the context of infection. Here we report the ability o...

  5. BpsR Modulates Bordetella Biofilm Formation by Negatively Regulating the Expression of the Bps Polysaccharide

    OpenAIRE

    Conover, Matt S.; Redfern, Crystal J.; Ganguly, Tridib; Sukumar, Neelima; Sloan, Gina; Mishra, Meenu; Deora, Rajendar

    2012-01-01

    Bordetella bacteria are Gram-negative respiratory pathogens of animals, birds, and humans. A hallmark feature of some Bordetella species is their ability to efficiently survive in the respiratory tract even after vaccination. Bordetella bronchiseptica and Bordetella pertussis form biofilms on abiotic surfaces and in the mouse respiratory tract. The Bps exopolysaccharide is one of the critical determinants for biofilm formation and the survival of Bordetella in the murine respiratory tract. In...

  6. Detection of Intracellular Adhesion (ica Gene and Biofilm Formation Staphylococcus aureus Isolates from Clinical Blood Cultures

    Directory of Open Access Journals (Sweden)

    Mohsen Mirzaee

    2015-10-01

    Full Text Available Background: In fact the biofilms are composed of bacterial cells living inmulticellular structures such as tissues and organs embedded within a self-produced matrix of extracellular polymeric substance (EPS. Ability to attach and biofilm formation are the most important virulence factors Staphylococcus aureus isolates. The aims of this study were to detect intracellular adhesion (ica locus and its relation to the biofilm formation phenotype in clinical isolates of S. aureus isolated from bloodcultures.Methods: A total of 31 clinical S. aureus isolates were collected from Loghman Hospital of Tehran, Iran. In vitro biofilm formation ability was determined by microliter tissue culture plates. All clinical isolates were examined for determination the ica locus by using PCR method.Results: Twelve (38.7% of the isolates were strong biofilm producers. The results showed that 18(80.6% of the isolates carried icaD gene, whereas the prevalence of icaA, icaB and icaC were 51.6%, 45.1% and 77.4% respectively.Conclusions: S. aureus clinical isolates have different ability to form biofilm. This may be caused by the differences in the expression of biofilm related genes, genetic make-up and physiological conditions.

  7. Influence of flow on the structure of bacterial biofilms.

    OpenAIRE

    Stoodley, Paul; Boyle, John D.; Lappin-Scott, Hilary M.

    2000-01-01

    Bacteria attached to surfaces in biofilms are responsible for the contamination of industrial processes and many types of microbial infections and disease. Once established, biofilms are notoriously difficult to eradicate. A more complete understanding of how biofilms form and behave is crucial if we are to predict, and ultimately control, biofilm processes. A major breakthrough in biofilm research came in the early 1990’s when confocal scanning laser microscopy (CSLM) showed that biofilms fo...

  8. Current understanding of multi-species biofilms

    OpenAIRE

    Yang, Liang; Liu, Yang; Wu,Hong; Høiby, Niels; Molin, Søren; Zhi-jun SONG

    2011-01-01

    Direct observation of a wide range of natural microorganisms has revealed the fact that the majority of microbes persist as surface-attached communities surrounded by matrix materials, called biofilms. Biofilms can be formed by a single bacterial strain. However, most natural biofilms are actually formed by multiple bacterial species. Conventional methods for bacterial cleaning, such as applications of antibiotics and/or disinfectants are often ineffective for biofilm populations due to their...

  9. Nettoyage en place des lignes agro-industrielles : Etude Cinétique d'élimination des biofilms négatifs au sein des installations fermées dans les industries agroalimentaires.

    OpenAIRE

    Sylla, Yahaya

    2011-01-01

    This work deals with removal kinetics of bacterial biofilms potentially formed in commonly used equipment in agro-industries. Two bacterial species Pseudomonas and Bacillus with a strong ability to form biofilms in which the almost permanent presence is reported in the food industry (meat, milk, vegetables…) were chosen as relevant models for the study. Moreover Bacillus, potentially pathogenic bacteria can form spores which are known to strongly adhere to solid surfaces and for their ability...

  10. DNase-sensitive and -resistant modes of biofilm formation by Listeria monocytogenes

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    Marion eZetzmann

    2015-12-01

    Full Text Available Listeria monocytogenes is able to form biofilms on various surfaces and this ability is thought to contribute to persistence in the environment and on contact surfaces in the food industry. Extracellular DNA is a component of the biofilm matrix of many bacterial species and was shown to play a role in biofilm establishment of L. monocytogenes. In the present study, the effect of DNaseI treatment on biofilm formation of L. monocytogenes EGD-e was investigated under static and dynamic conditions in normal or diluted complex medium at different temperatures. Biofilm formation was quantified by crystal violet staining or visualized by confocal laser scanning microscopy. Biomass of surface-attached L. monocytogenes varies depending on temperature and dilution of media. Interestingly, L. monocytogenes EGD-e forms DNase-sensitive biofilms in diluted medium whereas in full strength medium DNaseI treatment had no effect. In line with these observations, extracellular DNA is present in the matrix of biofilms grown in diluted but not full strength medium and supernatants of biofilms grown in diluted medium contain chromosomal DNA. The DNase-sensitive phenotype could be clearly linked to reduced ionic strength in the environment since dilution of medium in PBS or saline abolished DNase sensitivity. Several other but not all species of the genus Listeria display DNase-sensitive and -resistant modes of biofilm formation. These results indicate that L. monocytogenes biofilms are DNase-sensitive especially at low ionic strength, which might favor bacterial lysis and release of chromosomal DNA. Since low nutrient concentrations with increased osmotic pressure are conditions frequently found in food processing environments, DNaseI treatment represents an option to prevent or remove Listeria biofilms in industrial settings.

  11. Inhibitory effect of zinc oxide nanoparticles on pseudomonas aeruginosa biofilm formation

    Directory of Open Access Journals (Sweden)

    Mohammad Hassani Sangani

    2015-04-01

    Full Text Available Objective(s: Bacterial biofilm formation causes many persistent and chronic infections. The matrix protects biofilm bacteria from exposure to innate immune defenses and antibiotic treatments. The purpose of this study was to evaluate the biofilm formation of clinical isolates of Pseudomonas aeruginosa and the activity of zinc oxide nanoparticles (ZnO NPs on biofilm. Materials and Methods: After collecting bacteria from clinical samples of hospitalized patients, the ability of organisms were evaluated to create biofilm by tissue culture plate (TCP assay. ZnO NPs were synthesized by sol gel method and the efficacy of different concentrations (50- 350 µg/ml of ZnO NPs was assessed on biofilm formation and also elimination of pre-formed biofilm by using TCP method. Results:The average diameter of synthesized ZnO NPs was 20 nm. The minimum inhibitory concentration of nanoparticles was 150- 158 μg/ml and the minimum bactericidal concentration was higher (325 µg/ml. All 15 clinical isolates of P. aeruginosa were able to produce biofilm. Treating the organisms with nanoparticles at concentrations of 350 μg/ml resulted in more than 94% inhibition in OD reduction%. Molecular analysis showed that the presence of mRNA of pslA gene after treating bacteria with ZnO NPs for 30 minutes. Conclusion: The results showed that ZnO NPs can inhibit the establishment of P. aeruginosa biofilms and have less effective in removing pre-formed biofilm. However the tested nanoparticles exhibited anti-biofilm effect, but mRNA of pslA gene could be still detected in the medium by RT-PCR technique after 30 minutes treatment with ZnO.

  12. Beneficial biofilms

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    Sara R Robertson

    2015-10-01

    Full Text Available Surface-adherent biofilm growth is a common trait of bacteria and other microorganisms in nature. Within biofilms, organisms are present in high density and are enmeshed in an organic matrix containing polysaccharides and other molecules. The close proximity of organisms within biofilms facilitates microbial interactions and signaling, including many metabolic processes in which consortia rather than individual organisms participate. Biofilm growth also enables microorganisms to withstand chemical and biological stresses. Here, we review some current literature and document representative beneficial aspects of biofilms using examples from wastewater treatment, microbial fuel cells, biological repair (biocementation of stonework, and biofilm protection against Candida albicans infections. Finally, we address a chemical ecology strategy whereby desired microbial succession and beneficial biofilm formation can be encouraged via manipulation of culture conditions and bacterial signaling.

  13. Physiological integration affects growth form and competitive ability in clonal plants

    Czech Academy of Sciences Publication Activity Database

    Herben, Tomáš

    2004-01-01

    Roč. 18, - (2004), s. 493-520. ISSN 0269-7653 R&D Projects: GA ČR(CZ) GA206/02/0953 Institutional research plan: CEZ:AV0Z6005908 Keywords : competitive ability * Physiological integration * clonal plant s Subject RIV: EF - Botanics Impact factor: 3.215, year: 2004

  14. Changes in the Frequency and In Vivo Vessel Forming Ability of Rhesus Monkey Circulating Endothelial Colony Forming Cells (ECFC) Across the Lifespan (Birth to Aged)

    OpenAIRE

    Shelley, W. Chris; Leapley, Alyssa C.; Huang, Lan; Critser, Paul J.; Mead, Laura E.; Zeng, Pingyu; Prater, Daniel; Ingram, David A.; Tarantal, Alice F; Yoder, Mervin C.

    2011-01-01

    We have identified a novel hierarchy of human endothelial colony forming cells (ECFC), which are functionally defined by their proliferative and clonogenic potential and in vivo vessel forming ability. Utilizing previously established clonogenic assays for defining different subpopulations of human ECFC, we now show that a hierarchy of ECFC, identical to the human system, can be isolated from the peripheral blood of rhesus monkeys (Macaca mulatta), and that the frequency of the circulating ce...

  15. Influence of copper surfaces on biofilm formation by Legionella pneumophila in potable water.

    Science.gov (United States)

    Gião, M S; Wilks, S A; Keevil, C W

    2015-04-01

    Legionella pneumophila is a waterborne pathogen that can cause Legionnaires' disease, a fatal pneumonia, or Pontiac fever, a mild form of disease. Copper is an antimicrobial material used for thousands of years. Its incorporation in several surface materials to control the transmission of pathogens has been gaining importance in the past decade. In this work, the ability of copper to control the survival of L. pneumophila in biofilms was studied. For that, the incorporation of L. pneumophila in polymicrobial drinking water biofilms formed on copper, PVC and PEX, and L. pneumophila mono-species biofilms formed on copper and uPVC were studied by comparing cultivable and total numbers (quantified by peptide nucleic acid (PNA) hybridisation). L. pneumophila was never recovered by culture from heterotrophic biofilms; however, PNA-positive numbers were slightly higher in biofilms formed on copper (5.9 × 10(5) cells cm(-2)) than on PVC (2.8 × 10(5) cells cm(-2)) and PEX (1.7 × 10(5) cells cm(-2)). L. pneumophila mono-species biofilms grown on copper gave 6.9 × 10(5) cells cm(-2) for PNA-positive cells and 4.8 × 10(5) CFU cm(-2) for cultivable numbers, showing that copper is not directly effective in killing L. pneumophila. Therefore previous published studies showing inactivation of L. pneumophila by copper surfaces in potable water polymicrobial species biofilms must be carefully interpreted. PMID:25686789

  16. Intrigues of biofilm: A perspective in veterinary medicine

    Science.gov (United States)

    Abdullahi, Umar Faruk; Igwenagu, Ephraim; Mu’azu, Anas; Aliyu, Sani; Umar, Maryam Ibrahim

    2016-01-01

    Biofilm has a tremendous impact in the field of veterinary medicine, especially the livestock industry, leading to a serious economic loss. Over the years, little attention has been given to biofilm in animals with most of the research geared toward human biofilm diseases. The greatest challenge posed by biofilm is in its incredible ability to resist most of the currently existing antibiotics. This mystery can best be demystified through understanding the mechanism of the quorum sensing which regulate the pathophysiology of biofilm. Ability of biofilm formation in a variety of inanimate surfaces such as animal food contact surfaces is responsible for a host of biofilm diseases affecting animals and humans. In this review, we highlighted some of the challenges of biofilm in livestock and food industries. Also highlighted are; mechanisms of biofilm development, best diagnostic approach and possible novel therapeutic measures needed to combat the menace of biofilm in veterinary medicine. PMID:27051178

  17. Intrigues of biofilm: A perspective in veterinary medicine

    Directory of Open Access Journals (Sweden)

    Umar Faruk Abdullahi

    2016-01-01

    Full Text Available Biofilm has a tremendous impact in the field of veterinary medicine, especially the livestock industry, leading to a serious economic loss. Over the years, little attention has been given to biofilm in animals with most of the research geared toward human biofilm diseases. The greatest challenge posed by biofilm is in its incredible ability to resist most of the currently existing antibiotics. This mystery can best be demystified through understanding the mechanism of the quorum sensing which regulate the pathophysiology of biofilm. Ability of biofilm formation in a variety of inanimate surfaces such as animal food contact surfaces is responsible for a host of biofilm diseases affecting animals and umans. In this review, we highlighted some of the challenges of biofilm in livestock and food industries. Also highlighted are; mechanisms of biofilm development, best diagnostic approach and possible novel therapeutic measures needed to combat the menace of biofilm in veterinary medicine.

  18. Detection of cell surface hydrophobicity, biofilm and fimbirae genes in salmonella isolated from tunisian clinical and poultry meat.

    Directory of Open Access Journals (Sweden)

    Fethi Ben Abdallah

    2015-04-01

    Full Text Available The aim of this study was to evaluate the ability of 15 serotypes of Salmonella to form biofilm on polystyrene, polyvinyl chloride (PVC and glass surfaces. .Initially slime production was assessed on CRA agar and hydrophobicity of 20 Salmonella strains isolated from poultry and human and two Salmonella enterica serovar Typhimurium references strains was achieved by microbial adhesion to n-hexadecane. In addition, biofilm formation on polystyrene, PVC and glass surfaces was also investigated by using MTT and XTT colorimetric assay. Further, distribution of Salmonella enterotoxin (stn, Salmonella Enteritidis fimbrial (sef and plasmid encoded fimbrial (pef genes among tested strains was achieved by PCR.Salmonella strains developed red and white colonies on CRA and they are considered as hydrophilic with affinity values to n-hexadecane ranged between 0.29% and 29.55%. Quantitative biofilm assays showed that bacteria are able to form biofilm on polystyrene with different degrees and 54.54% of strains produce a strong biofilm on glass. In addition, all the strains form only a moderate (54.54% and weak (40.91% biofilm on PVC. PCR detection showed that only S. Enteritidis harbour Sef gene, whereas Pef and stn genes were detected in S. Kentucky, S. Amsterdam, S. Hadar, S. Enteritidis and S. Typhimurium.Salmonella serotypes are able to form biofilm on hydrophobic and hydrophilic industrial surfaces. Biofilm formation of Salmonella on these surfaces has an increased potential to compromise food safety and potentiate public health risk.

  19. Developmental Abilities to Form Chunks in Immediate Memory and Its Non-Relationship to Span Development.

    Science.gov (United States)

    Mathy, Fabien; Fartoukh, Michael; Gauvrit, Nicolas; Guida, Alessandro

    2016-01-01

    Both adults and children -by the time they are 2-3 years old- have a general ability to recode information to increase memory efficiency. This paper aims to evaluate the ability of untrained children aged 6-10 years old to deploy such a recoding process in immediate memory. A large sample of 374 children were given a task of immediate serial report based on SIMON®, a classic memory game made of four colored buttons (red, green, yellow, blue) requiring players to reproduce a sequence of colors within which repetitions eventually occur. It was hypothesized that a primitive ability across all ages (since theoretically already available in toddlers) to detect redundancies allows the span to increase whenever information can be recoded on the fly. The chunkable condition prompted the formation of chunks based on the perceived structure of color repetition within to-be-recalled sequences of colors. Our result shows a similar linear improvement of memory span with age for both chunkable and non-chunkable conditions. The amount of information retained in immediate memory systematically increased for the groupable sequences across all age groups, independently of the average age-group span that was measured on sequences that contained fewer repetitions. This result shows that chunking gives young children an equal benefit as older children. We discuss the role of recoding in the expansion of capacity in immediate memory and the potential role of data compression in the formation of chunks in long-term memory. PMID:26941675

  20. The ability to form full-length intron RNA circles is a general property of nuclear group I introns

    DEFF Research Database (Denmark)

    Nielsen, Henrik; Fiskaa, Tonje; Birgisdottir, Asa Birna; Haugen, Peik; Einvik, Christer; Johansen, Steinar

    2003-01-01

    at the expense of the host. The circularization pathway has distinct structural requirements that differ from those of splicing and appears to be specifically suppressed in vivo. The ability to form full-length circles is found in all types of nuclear group I introns, including those from the...

  1. Biofilm enhanced subsurface sequestration of supercritical CO2

    Science.gov (United States)

    Mitchell, A. C.; Phillips, A.; Hiebert, R.; Gerlach, R.; Kaszuba, J.; Cunningham, A.

    2007-12-01

    In order to develop subsurface CO2 storage as a viable engineered mechanism to reduce concentrations of atmospheric CO2, any potential ¡°leakage¡± of injected supercritical CO2 (scCO2) from the ground to the atmosphere must be reduced. Here, we investigate the utility of biofilms, which are microorganism assemblages firmly attached to a surface, as a means of reducing scCO2 leakage. Firstly, experiments were performed to test whether biofilms were more resilient than planctonic cells to scCO2. Bacillus mojavensis biofilms were grown on a sand support matrix in scCO2 extractor cartridges at 30°C. B. mojavensis was also grown under suspended planctonic conditions in the same media overnight and aliquots were decanted into scCO2 extractor cartridges. Biofilm and suspended B. mojavensis samples were processed on a Supercritical Fluid Extractor with pressurization to 2000 psi at 35°C, and a 20 minute flow of scCO2. Suspended growth samples revealed a 3 log reduction in cell viability while biofilm only showed a 1 log reduction, demonstrating that B. mojavensis biofilms are more resilient than planctonic cells to scCO2. Protective extra cellular polymeric substances which make up the biofilm matrix likely provide a protective barrier against scCO2. Secondly, the ability of biofilms to grow under high pressure and reduce the permeability of porous geological matrices was investigated using a unique high pressure (8.9MPa), moderate temperature (¡Ý 32°C) flow reactor containing 40 millidarcy Berea sandstone cores. The flow reactor was inoculated with the biofilm forming organism Shewanella fridgidimarina. Electron microscopy of the rock core revealed substantial biofilm accumulation in rock pores which resulted in core permeability. Permeability did not increase in response to starvation and scCO2 challenges. Viable population assays of organisms in the effluent indicated survival of the microorganisms following scCO2 challenges of <71h and starvation for <363h

  2. Tracer measurements reveal experimental evidence of biofilm consolidation

    OpenAIRE

    Casey, Eoin

    2007-01-01

    The ability to simultaneously measure both biofilm thickness and the mass transfer coefficient of an inert tracer through it provides a powerful method to study biofilm development. In this communication previously published data has been collated to interpret global trends in biofilm structure during the transition towards steady-state. It appears that sudden changes in biofilm structure (directly related to the rate of change of biofilm mass transfer resistance) may occur following transiti...

  3. Effect of Yttrium Addition on Glass Forming Ability of ZrCuAlSi Alloy

    International Nuclear Information System (INIS)

    The effect of yttrium addition on glass formation of a ZrCuAlSi alloy is investigated. The maximum diameter 8mm of the glassy rods for (Zr46.3Cu43.3Al8.9Si1.5)100−xYx alloy with x = 2.5 is obtained by copper mould casting. Apparent enhancement of the glass formation ability is found with addition of yttrium, mainly due to the purification of the alloy melt and the suppression of formation of the primary phases by yttrium. (condensed matter: structure, mechanical and thermal properties)

  4. Exploring Dangerous Connections between Klebsiella pneumoniae Biofilms and Healthcare-Associated Infections

    Directory of Open Access Journals (Sweden)

    Maria Bandeira

    2014-08-01

    Full Text Available Healthcare-associated infections (HAI are a huge public health concern, particularly when the etiological agents are multidrug resistant. The ability of bacteria to develop biofilm is a helpful skill, both to persist within hospital units and to increase antibiotic resistance. Although the links between antibiotic resistance, biofilms assembly and HAI are consensual, little is known about biofilms. Here, electron microscopy was adopted as a tool to investigate biofilm structures associated with increased antibiotic resistance. The K. pneumoniae strains investigated are able to assemble biofilms, albeit with different kinetics. The biofilm structure and the relative area fractions of bacteria and extracellular matrix depend on the particular strain, as well as the minimal inhibitory concentration (MIC for the antibiotics. Increased values were found for bacteria organized in biofilms when compared to the respective planktonic forms, except for isolates Kp45 and Kp2948, the MIC values for which remained unchanged for fosfomycin. Altogether, these results showed that the emergence of antimicrobial resistance among bacteria responsible for HAI is a multifactorial phenomenon dependent on antibiotics and on bacteria/biofilm features.

  5. D-amino acids trigger biofilm disassembly.

    Science.gov (United States)

    Kolodkin-Gal, Ilana; Romero, Diego; Cao, Shugeng; Clardy, Jon; Kolter, Roberto; Losick, Richard

    2010-04-30

    Bacteria form communities known as biofilms, which disassemble over time. In our studies outlined here, we found that, before biofilm disassembly, Bacillus subtilis produced a factor that prevented biofilm formation and could break down existing biofilms. The factor was shown to be a mixture of D-leucine, D-methionine, D-tyrosine, and D-tryptophan that could act at nanomolar concentrations. D-amino acid treatment caused the release of amyloid fibers that linked cells in the biofilm together. Mutants able to form biofilms in the presence of D-amino acids contained alterations in a protein (YqxM) required for the formation and anchoring of the fibers to the cell. D-amino acids also prevented biofilm formation by Staphylococcus aureus and Pseudomonas aeruginosa. D-amino acids are produced by many bacteria and, thus, may be a widespread signal for biofilm disassembly. PMID:20431016

  6. Biofilm Infections

    DEFF Research Database (Denmark)

    A still increasing interest and emphasis on the sessile bacterial lifestyle biofilms has been seen since it was realized that the vast majority of the total microbial biomass exists as biofilms. Aggregation of bacteria was first described by Leeuwenhoek in 1677, but only recently recognized as...... being important in chronic infection. In 1993 the American Society for Microbiology (ASM) recognized that the biofilm mode of growth was relevant to microbiology. This book covers both the evidence for biofilms in many chronic bacterial infections as well as the problems facing these infections such as...... diagnostics, pathogenesis, treatment regimes and in vitro and in vivo models for studying biofilms. This is the first scientific book on biofilm infections, chapters written by the world leading scientist and clinicians. The intended audience of this book is scientists, teachers at university level as well as...

  7. Biofilm Infections

    DEFF Research Database (Denmark)

    Bjarnsholt, Thomas; Jensen, Peter Østrup; Moser, Claus Ernst; Høiby, Niels

    being important in chronic infection. In 1993 the American Society for Microbiology (ASM) recognized that the biofilm mode of growth was relevant to microbiology. This book covers both the evidence for biofilms in many chronic bacterial infections as well as the problems facing these infections such as......A still increasing interest and emphasis on the sessile bacterial lifestyle biofilms has been seen since it was realized that the vast majority of the total microbial biomass exists as biofilms. Aggregation of bacteria was first described by Leeuwenhoek in 1677, but only recently recognized as...... diagnostics, pathogenesis, treatment regimes and in vitro and in vivo models for studying biofilms. This is the first scientific book on biofilm infections, chapters written by the world leading scientist and clinicians. The intended audience of this book is scientists, teachers at university level as well as...

  8. The biofilm produced by Burkholderia cepacia complex: molecular aspects and relationship with exopolysaccharides

    Directory of Open Access Journals (Sweden)

    Lucia Corich

    2010-12-01

    Full Text Available Introduction. In cystic fibrosis patients, Burkholderia cepacia complex (Bcc can cause serious pulmonary chronic infections thanks in part to the ability to form biofilm, matrix rich in exopolysaccharides. In Bcc grown in the planktonic state, the main exopolysaccharide is cepacian while in biofilm its presence is controversial. Methods and Results. Two clinical isolates, named BTS7 and BTS2, were studied. BTS7 produces abundant cepacian but not much biofilm (quantified by colorimetric method.At least two of the genes involved in cepacian biosynthesis are not necessary for biofilm production as two BTS7 derivatives, bceB and bceQ knocked out by transposon mutagenesis, produce biofilm levels comparable to the wild-type. BTS2 sinthesyzes cepacian only if cultured on a specific medium. It has been colonizing a patient for almost ten years, showing a significant reduction of biofilm production during this period. This reduction did not appear together with the lack of factors required for the initial adhesion to the surface, or to differences in some of the Bcc genes involved in biofilm formation. Moreover, sequencing of its bce locus revealed a bceX gene, absent in BTS7, coding for a trascriptional regulator. Its product may negatively regulate the production of cepacian but not the one of other polysaccharides, promoting the formation of biofilm. Conclusions. Cepacian seems to be marginal in the production of biofilm.The reduced ability to produce biofilm of BTS2 suggests possible gene mutations occurred over time. Using custom arrays we will compare the gene expression of the BTS2 isolates, to identify the genes responsible for the observed phenotypic changes.

  9. Inhibition of Salmonella enterica biofilm formation using small-molecule adenosine mimetics.

    Science.gov (United States)

    Koopman, Jacob A; Marshall, Joanna M; Bhatiya, Aditi; Eguale, Tadesse; Kwiek, Jesse J; Gunn, John S

    2015-01-01

    Biofilms have been widely implicated in chronic infections and environmental persistence of Salmonella enterica, facilitating enhanced colonization of surfaces and increasing the ability of the bacteria to be transmitted to new hosts. Salmonella enterica serovar Typhi biofilm formation on gallstones from humans and mice enhances gallbladder colonization and bacterial shedding, while Salmonella enterica serovar Typhimurium biofilms facilitate long-term persistence in a number of environments important to food, medical, and farming industries. Salmonella regulates expression of many virulence- and biofilm-related processes using kinase-driven pathways. Kinases play pivotal roles in phosphorylation and energy transfer in cellular processes and possess an ATP-binding pocket required for their functions. Many other cellular proteins also require ATP for their activity. Here we test the hypothesis that pharmacological interference with ATP-requiring enzymes utilizing adenosine mimetic compounds would decrease or inhibit bacterial biofilm formation. Through the screening of a 3,000-member ATP mimetic library, we identified a single compound (compound 7955004) capable of significantly reducing biofilm formation by S. Typhimurium and S. Typhi. The compound was not bactericidal or bacteriostatic toward S. Typhimurium or cytotoxic to mammalian cells. An ATP-Sepharose affinity matrix technique was used to discover potential protein-binding targets of the compound and identified GroEL and DeoD. Compound 7955004 was screened against other known biofilm-forming bacterial species and was found to potently inhibit biofilms of Acinetobacter baumannii as well. The identification of a lead compound with biofilm-inhibiting capabilities toward Salmonella provides a potential new avenue of therapeutic intervention against Salmonella biofilm formation, with applicability to biofilms of other bacterial pathogens. PMID:25313216

  10. BIOFILM FORMATION OF Vibrio cholerae ON STAINLESS STEEL USED IN FOOD PROCESSING

    Science.gov (United States)

    FERNÁNDEZ-DELGADO, Milagro; ROJAS, Héctor; DUQUE, Zoilabet; SUÁREZ, Paula; CONTRERAS, Monica; GARCÍA-AMADO, M. Alexandra; ALCIATURI, Carlos

    2016-01-01

    Vibrio cholerae represents a significant threat to human health in developing countries. This pathogen forms biofilms which favors its attachment to surfaces and its survival and transmission by water or food. This work evaluated the in vitro biofilm formation of V. cholerae isolated from clinical and environmental sources on stainless steel of the type used in food processing by using the environmental scanning electron microscopy (ESEM). Results showed no cell adhesion at 4 h and scarce surface colonization at 24 h. Biofilms from the environmental strain were observed at 48 h with high cellular aggregations embedded in Vibrio exopolysaccharide (VPS), while less confluence and VPS production with microcolonies of elongated cells were observed in biofilms produced by the clinical strain. At 96 h the biofilms of the environmental strain were released from the surface leaving coccoid cells and residual structures, whereas biofilms of the clinical strain formed highly organized structures such as channels, mushroom-like and pillars. This is the first study that has shown the in vitro ability of V. cholerae to colonize and form biofilms on stainless steel used in food processing. PMID:27253749

  11. BIOFILM FORMATION OF Vibrio cholerae ON STAINLESS STEEL USED IN FOOD PROCESSING.

    Science.gov (United States)

    Fernández-Delgado, Milagro; Rojas, Héctor; Duque, Zoilabet; Suárez, Paula; Contreras, Monica; García-Amado, M Alexandra; Alciaturi, Carlos

    2016-01-01

    Vibrio cholerae represents a significant threat to human health in developing countries. This pathogen forms biofilms which favors its attachment to surfaces and its survival and transmission by water or food. This work evaluated the in vitro biofilm formation of V. cholerae isolated from clinical and environmental sources on stainless steel of the type used in food processing by using the environmental scanning electron microscopy (ESEM). Results showed no cell adhesion at 4 h and scarce surface colonization at 24 h. Biofilms from the environmental strain were observed at 48 h with high cellular aggregations embedded in Vibrio exopolysaccharide (VPS), while less confluence and VPS production with microcolonies of elongated cells were observed in biofilms produced by the clinical strain. At 96 h the biofilms of the environmental strain were released from the surface leaving coccoid cells and residual structures, whereas biofilms of the clinical strain formed highly organized structures such as channels, mushroom-like and pillars. This is the first study that has shown the in vitro ability of V. cholerae to colonize and form biofilms on stainless steel used in food processing. PMID:27253749

  12. Multiparameter Assessments To Determine the Effects of Sugars and Antimicrobials on a Polymicrobial Oral Biofilm

    OpenAIRE

    Yang, Ying; Sreenivasan, Prem K; Subramanyam, Ravi; Cummins, Diane

    2006-01-01

    Clinical studies indicate relationships between dental plaque, a naturally formed biofilm, and oral diseases. The crucial role of nonmicrobial biofilm constituents in maintaining biofilm structure and biofilm-specific attributes, such as resistance to shear and viscoelasticity, is increasingly recognized. Concurrent analyses of the diverse nonmicrobial biofilm components for multiparameter assessments formed the focus of this investigation. Comparable numbers of Actinomyces viscosus, Streptoc...

  13. Inhibitory activity of thymol on native and mature Gardnerella vaginalis biofilms: in vitro study.

    Science.gov (United States)

    Braga, Pier Carlo; Dal Sasso, Monica; Culici, Maria; Spallino, Alessandra

    2010-01-01

    Bacterial vaginosis (BV) is the most frequent diagnosis made in women with lower genital tract symptoms. It has recently been observed that 90 % of subjects with BV show the growth of bacteria in the form of biofilms as against only 10% without BV, and that Gardnerella vaginalis was the predominant species. The propensity of G. vaginalis to form biofilm is clinically relevant because this form of growth allows it to tolerate higher concentrations of certain antibiotics, thus increasing the possibilty of recurrent BV even after apparently curative therapy. The aim of this study was to investigate whether thymol (CAS 89-83-8), a molecule present in thyme essential oil, that is credited with having a series of pharmacological properties including antimicrobial and antifungal effects, can interfere with newly formed and mature G. vaginalis biofilms. The ability of G. vaginalis ATCC 49145 and two G. vaginalis strains isolated from human BV to form biofilm in flat-bottomed 96-well microtitre plates was verified, and the effects of thymol concentrations ranging from 1 to 1/16 MIC (minimum inhibitory concentration) on preformed and mature biofilms was investigated by means of spectrophotometric analysis, Nomarski interference contrast microscopy, and fluorescence microscopy with live-dead cell visualisation (SYTO 9 and propidium iodide). Native biofilm was inhibited by concentrations ranging from 1 MIC to 1/8 MIC (32.77% +/- 2.37 to 11.39% +/- 1.46), and mature biofilm was inhibited by concentrations ranging from 1 MIC to 1/4 MIC (26.18% +/- 1.36 to 13.20% +/- 1.44). Nomarski interference contrast and fluorescence microscopy visually confirmed these findings. As biofilm is a multi-factorial phenomenon, the multiple mechanisms of thymol may act on different steps in the evolution of mature biofilm. PMID:21175040

  14. Microfluidic Approaches to Bacterial Biofilm Formation

    OpenAIRE

    Hee-Deung Park; Junghyun Kim; Seok Chung

    2012-01-01

    Bacterial biofilms—aggregations of bacterial cells and extracellular polymeric substrates (EPS)—are an important subject of research in the fields of biology and medical science. Under aquatic conditions, bacterial cells form biofilms as a mechanism for improving survival and dispersion. In this review, we discuss bacterial biofilm development as a structurally and dynamically complex biological system and propose microfluidic approaches for the study of bacterial biofilms. Biofilms develop t...

  15. Pseudomonas biofilm matrix composition and niche biology

    OpenAIRE

    Mann, Ethan E.; Wozniak, Daniel J.

    2012-01-01

    Biofilms are a predominant form of growth for bacteria in the environment and in the clinic. Critical for biofilm development are adherence, proliferation, and dispersion phases. Each of these stages includes reinforcement by, or modulation of, the extracellular matrix. Pseudomonas aeruginosa has been a model organism for the study of biofilm formation. Additionally, other Pseudomonas species utilize biofilm formation during plant colonization and environmental persistence. Pseudomonads produ...

  16. Career Adapt-Abilities Scale--Portugal Form: Psychometric Properties and Relationships to Employment Status

    Science.gov (United States)

    Duarte, M. Eduarda; Soares, M. C.; Fraga, S.; Rafael, M.; Lima, M. R.; Paredes, I.; Agostinho, R.; Djalo, A.

    2012-01-01

    The Career-Adaptabilities Scale (CAAS)--Portugal Form consists of four scales, each with seven items, which measure concern, control, curiosity, and confidence as psychosocial resources for managing occupational transitions, developmental tasks, and work traumas. Internal consistency estimates for the subscale and total scores ranged from good to…

  17. Study on Mathematics Teacher Candidates' Ability to Form and Mathematically Define Geometric Surfaces

    Science.gov (United States)

    Ünan, Zuhal

    2016-01-01

    The aim of this study was to determine how successful elementary school teacher candidates are in forming and mathematically defining the surfaces of spheres, cones, cylinders and circular objects with the aid of various geometric elements. The study group consisted of a total of 40 teacher candidates in their fourth year attending a public…

  18. Efficacy of dental unit waterlines disinfectants on a polymicrobial biofilm.

    Science.gov (United States)

    Costa, Damien; Girardot, Marion; Bertaux, Joanne; Verdon, Julien; Imbert, Christine

    2016-03-15

    Due to their high surface-volume ratio, their laminar flow and frequent stagnation periods, dental unit waterlines (DUWL) foster the attachment of microorganisms and the development of biofilm, resulting in the continuous contamination of the outlet water from dental units; this contamination may be responsible for a potential risk of infection due to the exposure of patients and medical staff to droplet inhalation or splashed water. In this study, the anti-biofilm activity of three disinfectants recommended by dental unit manufacturers -Calbenium(©), Oxygenal 6(©) and Sterispray(©) - was evaluated. A dynamic model simulating DUWL conditions was developed and polymicrobial biofilms containing bacteria (Pseudomonas aeruginosa), fungi (Candida albicans) and Free Living Amoeba (FLA: Vermamoeba vermiformis) were allowed to form. The ability of disinfectants to reduce biofilm formation or to eradicate an already formed biofilm was evaluated. Results showed the various effects of the tested disinfectants according to their composition, concentration and the targeted species. V. vermiformis was resistant to disinfectants, regardless of the tested concentrations and the concentrations recommended by manufacturers were not the most appropriate. Results also showed that Calbenium(©) was the most effective disinfectant to reduce already formed biofilms; its maximum efficiency was observed from 0.5% on both P. aeruginosa and C. albicans compared to 2 and 3% respectively for Sterispray(©). The maximum efficiency of Oxygenal(©) was observed from 3% on P. aeruginosa but Oxygenal(©) was unable to totally eliminate C. albicans in the tested conditions, contrary to other disinfectants. Calbenium(©) was able to prevent biofilm formation efficiently even if it displayed no prophylactic activity against V. vermiformis. Overall, the FLA survival may contribute to maintaining other species. Finally the tested disinfectants were partially active against sessile microorganisms

  19. Pseudomonas aeruginosa Biofilms

    DEFF Research Database (Denmark)

    Alhede, Maria; Bjarnsholt, Thomas; Givskov, Michael;

    2014-01-01

    biofilms, which protect the aggregated, biopolymer-embedded bacteria from the detrimental actions of antibiotic treatments and host immunity. A key component in the protection against innate immunity is rhamnolipid, which is a quorum sensing (QS)-regulated virulence factor. QS is a cell-to-cell signaling...... mechanism used to coordinate expression of virulence and protection of aggregated biofilm cells. Rhamnolipids are known for their ability to cause hemolysis and have been shown to cause lysis of several cellular components of the human immune system, for example, macrophages and polymorphonuclear leukocytes...

  20. Rapid evaluation of the antibiotic susceptibility of fuel ethanol contaminant biofilms.

    Science.gov (United States)

    Rich, Joseph O; Leathers, Timothy D; Nunnally, Melinda S; Bischoff, Kenneth M

    2011-01-01

    Bacterial contaminants from commercial fuel ethanol production facilities were previously shown to form biofilms as mixed cultures under laboratory conditions. In this study, a rapid assay was developed to simultaneously compare isolates for their ability to form biofilms as pure cultures. A total of 10 strains were isolated from a dry-grind fuel ethanol plant that routinely doses with virginiamycin. These were identified by sequence analysis as six strains of Lactobacillus fermentum, two strains of L. johnsonii, and one strain each of L. mucosae and L. amylovorus. Isolates exhibited a range of susceptibility to virginiamycin in a planktonic assay, with MIC's (minimum inhibitory concentration) of ≤0.5-16 μg/ml. Even though all strains were isolated from a mixed culture biofilm, they varied greatly in their ability to form biofilms as pure cultures. Surprisingly, growth as biofilms did not appear to provide resistance to virginiamycin, even if biofilms were grown for 144 h prior to antibiotic challenge. PMID:20855199

  1. Effects of Aronia melanocarpa Constituents on Biofilm Formation of Escherichia coli and Bacillus cereus

    Directory of Open Access Journals (Sweden)

    Marie Bräunlich

    2013-12-01

    Full Text Available Many bacteria growing on surfaces form biofilms. Adaptive and genetic changes of the microorganisms in this structure make them resistant to antimicrobial agents. Biofilm-forming organisms on medical devices can pose serious threats to human health. Thus, there is a need for novel prevention and treatment strategies. This study aimed to evaluate the ability of Aronia melanocarpa extracts, subfractions and compounds to prevent biofilm formation and to inhibit bacterial growth of Escherichia coli and Bacillus cereus in vitro. It was found that several aronia substances possessed anti-biofilm activity, however, they were not toxic to the species screened. This non-toxic inhibition may confer a lower potential for resistance development compared to conventional antimicrobials.

  2. Dendrimers and polyamino-phenolic ligands: activity of new molecules against Legionella pneumophila biofilms.

    Directory of Open Access Journals (Sweden)

    Elisa Andreozzi

    2016-03-01

    Full Text Available Legionnaires’ disease is a potentially fatal pneumonia caused by Legionella pneumophila, an aquatic bacterium often found within the biofilm niche. In man-made water systems microbial biofilms increase the resistance of legionella to disinfection, posing a significant threat to public health. Disinfection methods currently used in water systems have been shown to be ineffective against legionella over the long-term, allowing recolonization by the biofilm-protected microorganisms. In this study, the anti-biofilm activity of previously fabricated polyamino-phenolic ligands and polyamidoamine dendrimers was investigated against legionella mono-species and multi-species biofilms formed by L. pneumophila in association with other bacteria that can be found in tap water (Aeromonas hydrophila, Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae. Bacterial ability to form biofilms was verified using a crystal violet colorimetric assay and testing cell viability by real-time quantitative PCR and Plate Count assay. The concentration of the chemicals tested as anti-biofilm agents was chosen based on cytotoxicity assays: the highest non-cytotoxic chemical concentration was used for biofilm inhibition assays, with dendrimer concentration ten-fold higher than polyamino-phenolic ligands. While Macrophen and Double Macrophen were the most active substances among polyamino-phenolic ligands, dendrimers were overall two-fold more effective than all other compounds with a reduction up to 85% and 73% of legionella and multi-species biofilms, respectively. Chemical interaction with matrix molecules is hypothesized, based on SEM images and considering the low or absent anti-microbial activity on planktonic bacteria showed by flow cytometry. These data suggest that the studied compounds, especially dendrimers, could be considered as novel molecules in the design of research projects aimed at the development of efficacious anti-biofilm disinfection

  3. Dendrimers and Polyamino-Phenolic Ligands: Activity of New Molecules Against Legionella pneumophila Biofilms.

    Science.gov (United States)

    Andreozzi, Elisa; Barbieri, Federica; Ottaviani, Maria F; Giorgi, Luca; Bruscolini, Francesca; Manti, Anita; Battistelli, Michela; Sabatini, Luigia; Pianetti, Anna

    2016-01-01

    Legionnaires' disease is a potentially fatal pneumonia caused by Legionella pneumophila, an aquatic bacterium often found within the biofilm niche. In man-made water systems microbial biofilms increase the resistance of legionella to disinfection, posing a significant threat to public health. Disinfection methods currently used in water systems have been shown to be ineffective against legionella over the long-term, allowing recolonization by the biofilm-protected microorganisms. In this study, the anti-biofilm activity of previously fabricated polyamino-phenolic ligands and polyamidoamine dendrimers was investigated against legionella mono-species and multi-species biofilms formed by L. pneumophila in association with other bacteria that can be found in tap water (Aeromonas hydrophila, Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae). Bacterial ability to form biofilms was verified using a crystal violet colorimetric assay and testing cell viability by real-time quantitative PCR and Plate Count assay. The concentration of the chemicals tested as anti-biofilm agents was chosen based on cytotoxicity assays: the highest non-cytotoxic chemical concentration was used for biofilm inhibition assays, with dendrimer concentration 10-fold higher than polyamino-phenolic ligands. While Macrophen and Double Macrophen were the most active substances among polyamino-phenolic ligands, dendrimers were overall twofold more effective than all other compounds with a reduction up to 85 and 73% of legionella and multi-species biofilms, respectively. Chemical interaction with matrix molecules is hypothesized, based on SEM images and considering the low or absent anti-microbial activity on planktonic bacteria showed by flow cytometry. These data suggest that the studied compounds, especially dendrimers, could be considered as novel molecules in the design of research projects aimed at the development of efficacious anti-biofilm disinfection treatments of water systems in

  4. Dendrimers and Polyamino-Phenolic Ligands: Activity of New Molecules Against Legionella pneumophila Biofilms

    Science.gov (United States)

    Andreozzi, Elisa; Barbieri, Federica; Ottaviani, Maria F.; Giorgi, Luca; Bruscolini, Francesca; Manti, Anita; Battistelli, Michela; Sabatini, Luigia; Pianetti, Anna

    2016-01-01

    Legionnaires’ disease is a potentially fatal pneumonia caused by Legionella pneumophila, an aquatic bacterium often found within the biofilm niche. In man-made water systems microbial biofilms increase the resistance of legionella to disinfection, posing a significant threat to public health. Disinfection methods currently used in water systems have been shown to be ineffective against legionella over the long-term, allowing recolonization by the biofilm-protected microorganisms. In this study, the anti-biofilm activity of previously fabricated polyamino-phenolic ligands and polyamidoamine dendrimers was investigated against legionella mono-species and multi-species biofilms formed by L. pneumophila in association with other bacteria that can be found in tap water (Aeromonas hydrophila, Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae). Bacterial ability to form biofilms was verified using a crystal violet colorimetric assay and testing cell viability by real-time quantitative PCR and Plate Count assay. The concentration of the chemicals tested as anti-biofilm agents was chosen based on cytotoxicity assays: the highest non-cytotoxic chemical concentration was used for biofilm inhibition assays, with dendrimer concentration 10-fold higher than polyamino-phenolic ligands. While Macrophen and Double Macrophen were the most active substances among polyamino-phenolic ligands, dendrimers were overall twofold more effective than all other compounds with a reduction up to 85 and 73% of legionella and multi-species biofilms, respectively. Chemical interaction with matrix molecules is hypothesized, based on SEM images and considering the low or absent anti-microbial activity on planktonic bacteria showed by flow cytometry. These data suggest that the studied compounds, especially dendrimers, could be considered as novel molecules in the design of research projects aimed at the development of efficacious anti-biofilm disinfection treatments of water systems

  5. 两种营养条件对尿路致病性大肠埃希菌生物膜形成的影响%Effects of two culture media on the growth of biofilm formed by uropathogenic Escherichia coli

    Institute of Scientific and Technical Information of China (English)

    葛新; 王辉; 张晓雷; 董小青

    2011-01-01

    目的 研究2种培养基对尿路致病性大肠埃希菌(UPEC)生物膜形成能力的影响.方法 将5株UPEC分别接种LB培养基或M63基础培养基,用结晶紫染色半定量法检测各菌株生物膜形成能力,分别用荧光显微镜和共聚焦显微镜观察绿色荧光蛋白标记的UPEC在2种培养基中的生物膜形成过程与厚度的差异.结果 5株UPEC在2种培养基中均为生物膜阳性菌株,早期生物膜的形成趋势基本一致,但同时期LB培养基中的生物膜菌量少于M63基础培养基中的生物膜菌量.共聚焦显微镜观察发现在M63基础培养基中各菌株生物膜最大平均厚度均大于LB培养基的相应数值(P<0.05).结论 培养基成分对UPEC生物膜的形成具有重要影响,M63基础培养基相对于LB培养基更适于培养UPEC生物膜.%Objective To compare the effects of two different levels of nutrition on the growth of biofilm formed by uropathogenic Escherichia coli (UPEC). Methods Five clinical strains of UPEC were cultured in Luria-Bertani (LB) broth or M63 minimal medium. The ability of biofilm formation was semiquantitatively measured by crystal violet stain. Green fluorescent protein-tagged strains were observed by a fluorescent microscope and a confocal microscope for the growth process and the levels of thickness of biofilm formed in the LB or M63. Results Five UPEC isolates were all biofilm positive strains. The early biofilm growth in LB was basically consistent with the growth in M63, but the bacterial population producing biofilm in LB was less than in M63 at the same time point. The confocal microscope observation showed that all strains formed thicker biofilm in M63 than in LB (P<0. 05). Conclusions The growth of UPEC biofilm was obviously affected by culture media. M63 minimal medium is more suitable for the formation of UPEC biofilm than LB.

  6. Discovering Biofilms: Inquiry-Based Activities for the Classroom

    Science.gov (United States)

    Redelman, Carly V.; Marrs, Kathleen; Anderson, Gregory G.

    2012-01-01

    In nature, bacteria exist in and adapt to different environments by forming microbial communities called "biofilms." We propose simple, inquiry-based laboratory exercises utilizing a biofilm formation assay, which allows controlled biofilm growth. Students will be able to qualitatively assess biofilm growth via staining. Recently, we developed a…

  7. A Subinhibitory Concentration of Clarithromycin Inhibits Mycobacterium avium Biofilm Formation

    OpenAIRE

    Carter, George; Young, Lowell S.; Bermudez, Luiz E.

    2004-01-01

    Mycobacterium avium causes disseminated infection in immunosuppressed individuals and lung infection in patients with chronic lung diseases. M. avium forms biofilm in the environment and possibly in human airways. Antibiotics with activity against the bacterium could inhibit biofilm formation. Clarithromycin inhibits biofilm formation but has no activity against established biofilm.

  8. D-Amino Acids Trigger Biofilm Disassembly

    OpenAIRE

    Kolodkin-Gal, Illana; Romero, Diego; Cao, Shugeng; Clardy, Jon; Kolter, Roberto; Losick, Richard

    2010-01-01

    Bacteria form communities known as biofilms, which disassemble over time. Here we found that prior to biofilm disassembly Bacillus subtilis produced a factor that prevented biofilm formation and could break down existing biofilms. The factor was shown to be a mixture of D-leucine, D-methionine, D-tyrosine and D-tryptophan that could act at nanomolar concentrations. D-amino acid treatment caused the release of amyloid fibers that linked cells in the biofilm together. Mutants able to form biofi...

  9. Structural Origin of the Enhanced Glass-Forming Ability Induced by Microalloying Y in the ZrCuAl Alloy

    Directory of Open Access Journals (Sweden)

    Gu-Qing Guo

    2016-03-01

    Full Text Available In this work, the structural origin of the enhanced glass-forming ability induced by microalloying Y in a ZrCuAl multicomponent system is studied by performing synchrotron radiation experiments combined with simulations. It is revealed that the addition of Y leads to the optimization of local structures, including: (1 more Zr-centered and Y-centered icosahedral-like clusters occur in the microstructure; (2 the atomic packing efficiency inside clusters and the regularity of clusters are both enhanced. These structural optimizations help to stabilize the amorphous structure in the ZrCuAlY system, and lead to a high glass-forming ability (GFA. The present work provides an understanding of GFAs in multicomponent alloys and will shed light on the development of more metallic glasses with high GFAs.

  10. Medical Biofilms

    OpenAIRE

    Bryers, James D.

    2008-01-01

    For more than two decades, Biotechnology and Bioengineering has documented research focused on natural and engineered microbial biofilms within aquatic and subterranean ecosystems, wastewater and waste-gas treatment systems, marine vessels and structures, and industrial bioprocesses. Compared to suspended culture systems, intentionally engineered biofilms are heterogeneous reaction systems that can increase reactor productivity, system stability, and provide inherent cell: product separation....

  11. Salmonella biofilms

    NARCIS (Netherlands)

    Castelijn, G.A.A.

    2013-01-01

    Biofilm formation by Salmonellaspp. is a problem in the food industry, since biofilms may act as a persistent source of product contamination. Therefore the aim of this study was to obtain more insight in the processes involved and the factors contributing to Salmonellabiofilm formation. A collectio

  12. Biofilm Development

    DEFF Research Database (Denmark)

    Tolker-Nielsen, Tim

    2015-01-01

    , and not by specific genetic programs. It appears that biofilm formation can occur through multiple pathways and that the spatial structure of the biofilms is species dependent as well as dependent on environmental conditions. Bacterial subpopulations, e.g., motile and nonmotile subpopulations, can develop...

  13. The Formation of Biofilms by Pseudomonas aeruginosa: A Review of the Natural and Synthetic Compounds Interfering with Control Mechanisms

    Directory of Open Access Journals (Sweden)

    Tsiry Rasamiravaka

    2015-01-01

    Full Text Available P. aeruginosa is an opportunistic pathogenic bacterium responsible for both acute and chronic infections. Beyond its natural resistance to many drugs, its ability to form biofilm, a complex biological system, renders ineffective the clearance by immune defense systems and antibiotherapy. The objective of this report is to provide an overview (i on P. aeruginosa biofilm lifestyle cycle, (ii on the main key actors relevant in the regulation of biofilm formation by P. aeruginosa including QS systems, GacS/GacA and RetS/LadS two-component systems and C-di-GMP-dependent polysaccharides biosynthesis, and (iii finally on reported natural and synthetic products that interfere with control mechanisms of biofilm formation by P. aeruginosa without affecting directly bacterial viability. Concluding remarks focus on perspectives to consider biofilm lifestyle as a target for eradication of resistant infections caused by P. aeruginosa.

  14. Phenotypic, Proteomic, and Genomic Characterization of a Putative ABC-Transporter Permease Involved in Listeria monocytogenes Biofilm Formation

    DEFF Research Database (Denmark)

    Zhu, Xinna; Liu, Weibing; Lametsch, René;

    2011-01-01

    The foodborne pathogen Listeria monocytogenes is able to form biofilms in food processing environments. Previously, we have reported that an lm.G_1771 gene (encoding a putative ABC-transporter permease) was involved in negative regulation of L. monocytogenes biofilm formation using LM-49, a biofilm......-enhanced mutant isolated on Tn917 mutagenesis (AEM 2008 p.7675–7683). Here, the possible action of this ABC-transporter permease in L. monocytogenes biofilm formation was characterized by phenotypic, proteomic, and genomic analyses using an lm.G_1771 gene deletant (Δ1771). The Δ1771 mutant exhibited the same...... enhanced ability for biofilm formation as the LM-49 strain using a crystal violet staining assay. DNA microarrays and two-dimensional gel electrophoresis revealed 49 and 11 differentially expressed (twofold or more) genes or proteins in Δ1771, respectively. The transcriptomics study indicated that lm...

  15. Biofilm Formation and Sloughing in Serratia marcescens Are Controlled by Quorum Sensing and Nutrient Cues

    OpenAIRE

    Rice, S A; Koh, K. S.; Queck, S. Y.; Labbate, M.; Lam, K W; Kjelleberg, S

    2005-01-01

    We describe here a role for quorum sensing in the detachment, or sloughing, of Serratia marcescens filamentous biofilms, and we show that nutrient conditions affect the biofilm morphotype. Under reduced carbon or nitrogen conditions, S. marcescens formed a classical biofilm consisting of microcolonies. The filamentous biofilm could be converted to a microcolony-type biofilm by switching the medium after establishment of the biofilm. Similarly, when initially grown as a microcolony biofilm, S....

  16. Effect of Nb on glass forming ability and plasticity of (Ti-Cu)-based bulk metallic glasses

    International Nuclear Information System (INIS)

    A Ti33Cu47Zr9Ni6Sn2Si1Nb2 bulk metallic glass has been developed by Nb partial substitution for Zr in Ti33Cu47Zr11Ni6Sn2Si1 alloy. The glass forming ability Ti33Cu47Zr9Ni6Sn2Si1Nb2 alloy has been investigated using differential scanning calorimetry and X-ray diffractometry. Partial Nb substitutes for Zr promote the glass forming ability. Ti33Cu47Zr9Ni6Sn2Si1Nb2 BMG with diameter of 3 mm can be fabricated by Cu-mold injection casting method. The glass forming ability of Ti33Cu47Zr9Ni6Sn2Si1Nb2 alloy is enhanced by stabilizing the undercooled liquid against crystallization. The plastic strain up to 2.5% was obtained for Ti33Cu47Zr9Ni6Sn2Si1Nb2 BMG compared to 0.15% for Ti33Cu47Zr11Ni6Sn2Si1 BMG, which demonstrates that small amount of Nb addition can have a dramatic effect on plasticity enhancement in Ti-Cu-based BMG. The intersection and branching of the shear bands are observed. The plastic strain of the Ti33Cu47Zr9Ni6Sn2Si1Nb2 BMG can be improved by the generation of nanocrystalline particles, which lead to multiple shear bands.

  17. Apatite-forming ability and magnetic properties of glass-ceramics containing zinc ferrite and calcium sodium phosphate phases

    International Nuclear Information System (INIS)

    Fine particles of zinc ferrite (ZnFe2O4) and calcium sodium phosphate [NaCaPO4] were crystallized in bulk x(ZnO, Fe2O3)(65-x)SiO220(CaO, P2O5)15Na2O (6 ≤ x ≤ 21 mol %) glassy matrix by heat treatment. Initial magnetization curves reveal that samples with x = 6 and 9 mol % zinc-iron oxide exhibit both ferrimagnetic and paramagnetic contributions, whereas, samples with x > 9 mol % zinc-iron oxide exhibit only ferrimagnetic contribution. This observation is supported by the disappearance of the electron paramagnetic resonance (EPR) absorption line centered at g ∼ 4.3 in samples with x > 9 mol % zinc-iron oxide. Apatite-forming ability of the glass-ceramic samples was investigated by examining apatite formation on the surface of the samples treated in simulated body fluid (SBF). Increase in apatite-forming ability was observed with an increase in zinc-iron oxide content. The results obtained have been used to understand the evolution of the apatite surface layer as a function of immersion time in SBF and glass-ceramic composition. A good correlation has also been observed between the magnetic nature of the samples and their apatite-forming ability. These materials are expected to find application as thermo-seeds in hyperthermia treatment of bone cancer.

  18. About forming of personality physical culture of students in the process of physical education (in aspect of presence of abilities

    Directory of Open Access Journals (Sweden)

    Belykh S.I.

    2013-01-01

    Full Text Available It is shown that practice of teaching of discipline «Physical education» does not provide forming of volume of abilities, sufficient for the origin of athletic activity. Prevail ability to pick up a place, sporting form, inventory depending on the type of physical exercises and ability on the observance of rules of the personal hygiene. In the questionnaire questioning 650 students (324 youths and 326 girls of the first and fourth courses took part. All of students visited employments on physical education at school and institute of higher. It is marked that the important task of amateurish athletic education is forming for the students of the personal experience of independent athletic, health and рекреационных employments. It is underlined that sense of amateurish athletic education of students consists in achievement by a man unity of mental and activity processes. Such processes are needed for an estimation and understanding of the state of the health, programming and residence of healthy way of life.

  19. Study of Biofilm Formation in C57Bl/6J Mice by Clinical Isolates of Helicobacter pylori

    Science.gov (United States)

    Attaran, Bahareh; Falsafi, Tahereh; Moghaddam, Ali N.

    2016-01-01

    Background/Aim: Despite the significant number of studies on H. pylori pathogenesis, not much data has been published concerning its ability to form biofilm in the host stomach. This study aims to evaluate the potential of clinical isolates of H. pylori to form biofilm in C57BL/6J mice model. Materials and Methods: Two strains of H. pylori were selected from a collection of clinical isolates; one (19B), an efficient biofilm producer and the other (4B), with weak biofilm-forming ability. Mice infected through gastric avages were examined after one and two weeks. Colonization was determined by CFU and urease activity; the anti-H. pylori IgA was measured by ELISA, and chronic infections were evaluated by histopathology. Bacterial communities within mucosal sections were studied by immunofluorescence and scanning electron microscopy (SEM). Results: Successful infection was obtained by both test strains. Strain 19B with higher ability to form biofilm in vitro also showed a higher colonization rate in the mice stomach one week after infection. Difference (P < 0.05) in IgA titers was observed between the infected mice and the controls as well as between 19B and 4B infected mice, two weeks after the last challenge. Immunofluorescence and SEM results showed tightly colonizing H. pylori in stomach mucosal sections and in squamous and glandular epithelium. Conclusion: H. pylori is able to form biofilm in the mouse stomach and induce IgA production, reflecting the same potential as in humans. Firm attachment of coccoid form bacteria to host cells suggests the importance of this state in biofilm formation by H. pylori. Occurrence of biofilm in squamous and glandular epithelium of the mouse stomach proposes that H. pylori can all parts of the upper gastrointestinal tract. PMID:26997224

  20. Sequencing of IncX-plasmids suggests ubiquity of mobile forms of a biofilm-promoting gene cassette recruited from Klebsiella pneumoniae.

    Directory of Open Access Journals (Sweden)

    Mette Burmølle

    Full Text Available Plasmids are a highly effective means with which genetic traits that influence human health, such as virulence and antibiotic resistance, are disseminated through bacterial populations. The IncX-family is a hitherto sparsely populated group of plasmids that are able to thrive within Enterobacteriaceae. In this study, a replicon-centric screening method was used to locate strains from wastewater sludge containing plasmids belonging to the IncX-family. A transposon aided plasmid capture method was then employed to transport IncX-plasmids from their original hosts (and co-hosted plasmids into a laboratory strain (Escherichia coli Genehogs® for further study. The nucleotide sequences of the three newly isolated IncX-plasmids (pLN126_33, pMO17_54, pMO440_54 and the hitherto un-sequenced type-plasmid R485 revealed a remarkable occurrence of whole or partial gene cassettes that promote biofilm-formation in Klebsiella pneumonia or E. coli, in all four instances. Two of the plasmids (R485 and pLN126_33 were shown to directly induce biofilm formation in a crystal violet retention assay in E. coli. Sequence comparison revealed that all plasmid-borne forms of the type 3 fimbriae encoding gene cassette mrkABCDF were variations of a composite transposon Tn6011 first described in the E. coli IncX plasmid pOLA52. In conclusion, IncX-plasmids isolated from Enterobacteriaceae over almost 40 years and on three different continents have all been shown to carry a type 3 fimbriae gene cassette mrkABCDF stemming from pathogenic K. pneumoniae. Apart from contributing general knowledge about IncX-plasmids, this study also suggests an apparent ubiquity of a mobile form of an important virulence factor and is an illuminating example of the recruitment, evolution and dissemination of genetic traits through plasmid-mediated horizontal gene transfer.

  1. Vibrio cholerae Biofilms and Cholera Pathogenesis.

    Directory of Open Access Journals (Sweden)

    Anisia J Silva

    2016-02-01

    Full Text Available Vibrio cholerae can switch between motile and biofilm lifestyles. The last decades have been marked by a remarkable increase in our knowledge of the structure, regulation, and function of biofilms formed under laboratory conditions. Evidence has grown suggesting that V. cholerae can form biofilm-like aggregates during infection that could play a critical role in pathogenesis and disease transmission. However, the structure and regulation of biofilms formed during infection, as well as their role in intestinal colonization and virulence, remains poorly understood. Here, we review (i the evidence for biofilm formation during infection, (ii the coordinate regulation of biofilm and virulence gene expression, and (iii the host signals that favor V. cholerae transitions between alternative lifestyles during intestinal colonization, and (iv we discuss a model for the role of V. cholerae biofilms in pathogenicity.

  2. Oral Streptococci Biofilm Formation on Different Implant Surface Topographies

    Directory of Open Access Journals (Sweden)

    Pedro Paulo Cardoso Pita

    2015-01-01

    Full Text Available The establishment of the subgingival microbiota is dependent on successive colonization of the implant surface by bacterial species. Different implant surface topographies could influence the bacterial adsorption and therefore jeopardize the implant survival. This study evaluated the biofilm formation capacity of five oral streptococci species on two titanium surface topographies. In vitro biofilm formation was induced on 30 titanium discs divided in two groups: sandblasted acid-etched (SAE- n=15 and as-machined (M- n=15 surface. The specimens were immersed in sterilized whole human unstimulated saliva and then in fresh bacterial culture with five oral streptococci species: Streptococcus sanguinis, Streptococcus salivarius, Streptococcus mutans, Streptococcus sobrinus, and Streptococcus cricetus. The specimens were fixed and stained and the adsorbed dye was measured. Surface characterization was performed by atomic force and scanning electron microscopy. Surface and microbiologic data were analyzed by Student’s t-test and two-way ANOVA, respectively (P0.05. S. sanguinis exhibited similar behavior to form biofilm on both implant surface topographies, while S. salivarius showed the lowest ability to form biofilm. It was concluded that biofilm formation on titanium surfaces depends on surface topography and species involved.

  3. Bacterial interactions in dental biofilm.

    Science.gov (United States)

    Huang, Ruijie; Li, Mingyun; Gregory, Richard L

    2011-01-01

    Biofilms are masses of microorganisms that bind to and multiply on a solid surface, typically with a fluid bathing the microbes. The microorganisms that are not attached but are free floating in an aqueous environment are termed planktonic cells. Traditionally, microbiology research has addressed results from planktonic bacterial cells. However, many recent studies have indicated that biofilms are the preferred form of growth of most microbes and particularly those of a pathogenic nature. Biofilms on animal hosts have significantly increased resistance to various antimicrobials compared to planktonic cells. These microbial communities form microcolonies that interact with each other using very sophisticated communication methods (i.e., quorum-sensing). The development of unique microbiological tools to detect and assess the various biofilms around us is a tremendously important focus of research in many laboratories. In the present review, we discuss the major biofilm mechanisms and the interactions among oral bacteria. PMID:21778817

  4. Splicing of Friend Murine Leukemia Virus env-mRNA Enhances Its Ability to Form Polysomes.

    Science.gov (United States)

    Machinaga, Akihito; Ishihara, Syuhei; Shirai, Akiko; Takase-Yoden, Sayaka

    2016-01-01

    Friend murine leukemia virus (MLV) belongs to the gamma retroviruses of the Retroviridae family. The positive-sense RNA of its genome contains a 5' long terminal repeat (LTR), 5' leader sequence, gag, pol, env, and 3' LTR. Transcription from proviral DNA begins from the R region of the 5' LTR and ends at the polyadenylation signal located at the R region of the other end of the 3' LTR. There is a 5' splice site in the 5' leader sequence and a 3' splice site at the 3' end of the pol region. Both full-length unspliced mRNAs and a singly spliced mRNA (env-mRNA) are produced in MLV-infected cells. The MLV Env protein plays important roles both in viral adsorption to host cells and in neuropathogenic disease in MLV-infected mice and rats. Understanding the regulatory mechanisms controlling Env expression is important for determining the functions of the Env protein. We have previously shown that splicing increases env-mRNA stability and translation efficiency. Generally, mRNA polysome formation correlates with translation efficiency. Therefore, here we investigated the effects of env-mRNA splicing on polysome formation to identify mechanisms for Env up-regulation due to splicing. We performed polysome profile analyses using Env-expression plasmids producing spliced or unspliced env-mRNA and showed that the former formed polysomes more efficiently than the latter. Thus, splicing of env-mRNA facilitated polysome formation, suggesting that this contributes to up-regulation of Env expression. We replaced the env region of the expression plasmids with a luciferase (luc) gene, and found that in this case both unspliced and spliced luc-mRNA formed polysomes to a similar extent. Thus, we conclude that whether mRNA polysome formation is affected by splicing depends on the structure of gene in question. PMID:26909075

  5. Biological Behavior of Osteoblast Cell and Apatite Forming Ability of the Surface Modified Ti Alloys.

    Science.gov (United States)

    Zhao, Jingming; Hwang, K H; Choi, W S; Shin, S J; Lee, J K

    2016-02-01

    Titanium as one kind of biomaterials comes in direct contact with the body, making evaluation of biocompatibility an important aspect to biomaterials development. Surface chemistry of titanium plays an important role in osseointegration. Different surface modification alters the surface chemistry and result in different biological response. In this study, three kinds of mixed acid solutions were used to treat Ti specimens to induce Ca-P formation. Following a strong mixed acid activation process, Ca-P coating successfully formed on the Ti surfaces in simulated body fluid. Strong mixed acid increased the roughness of the metal surface, because the porous and rough surface allows better adhesion between Ca-P coatings and substrates. After modification of titanium surface by mixed acidic solution and subsequently H2O2/HCL treatment evaluation of biocompatibility was conducted from hydroxyapatite formation by biomimetic process and cell viability on modified titanium surface. Nano-scale modification of titanium surfaces can alter cellular and tissue responses, which may benefit osseointegration and dental implant therapy. Results from this study indicated that surface treatment methods affect the surface morphology, type of TiO2 layer formed and subsequent apatite deposition and biological responses. The thermo scientific alamarblue cell viability assay reagent is used to quantitatively measure the viability of mammalian cell lines, bacteria and fungi by incorporating a rapid, sensitive and reliable fluorometric/colorimetric growth indicator, without any toxic and side effect to cell line. In addition, mixed acid treatment uses a lower temperature and shorter time period than widely used alkali treatment. PMID:27433617

  6. A prospective study on evaluation of pathogenesis, biofilm formation, antibiotic susceptibility of microbial community in urinary catheter

    Science.gov (United States)

    Younis, Khansa Mohammed; Usup, Gires; Ahmad, Asmat

    2015-09-01

    This study is aimed to isolate, detect biofilm formation ability and antibiotic susceptibility of urinary catheter adherent microorganisms from elderly hospitalized patient at the Universiti Kebangsaan Malaysia Medical Center. Microorganisms were isolated from three samples of urinary catheters (UC) surface; one of the acute vascular rejection patient (UCB) and two from benign prostate hyperplasia patients (UCC and UCD). A total of 100 isolates was isolated with 35 from UCB, 38 (UCC) and 28 (UCD). Ninety six were identified as Gram-negative bacilli, one Gram-positive bacilli and three yeasts. Results of biofilm forming on sterile foley catheter showed that all the isolates can form biofilm at different degrees; strong biofilm forming: 32% from the 35 isolates (UCB), 25% out of 38 isolates (UCC), 26% out of 28 isolates (UCD). As for moderate biofilm forming; 3% from UCB, 10% from UCC and 2% from UCD. Weak biofilm forming in UCC (3%). The antibiotic susceptibility for (UCB) isolates showed highly resistant to ampicillin, novobiocin and penicillin 100 (%), kanamycin (97%), tetracycline (94%), chloramphenicol (91%), streptomycin (77%) and showed low level of resistance to gentamycin (17%), while all the isolates from (UCC-D) showed high resistant towards ampicillin and penicillin, novobiocin (94%), tetracycline (61%), streptomycin (53%), gentamycin (50%) and low level of resistance to kanamycin (48%), chloramphenicol (47%). The findings indicate that these isolates can spread within the community on urinary catheters surface and produce strong biofilm, therefore, monitoring antibiotic susceptibility of bacteria isolated in the aggregation is recommended.

  7. The Relative Contributions of Physical Structure and Cell Density to the Antibiotic Susceptibility of Bacteria in Biofilms

    OpenAIRE

    Kirby, Amy E.; Garner, Kimberly; Levin, Bruce R.

    2012-01-01

    For many bacterial infections, noninherited mechanisms of resistance are responsible for extending the term of treatment and in some cases precluding its success. Among the most important of these noninherited mechanisms of resistance is the ability of bacteria to form biofilms. There is compelling evidence that bacteria within biofilms are more refractory to antibiotics than are planktonic cells. Not so clear, however, is the extent to which this resistance can be attributed to the structure...

  8. Effects of boron content on the glass-forming ability and mechanical properties of Co–B–Ta glassy alloys

    International Nuclear Information System (INIS)

    Highlights: • Glassy rods with diameters up to 3 mm were formed in Co92−xBxTa8 (x = 30−37.5) system. • The plasticity of Co–B–Ta glassy alloys increases with increasing B content. • The plastic strains of above 2.0% were observed in these glassy alloys. • These Co–B–Ta glassy alloys exhibit ultrahigh strength of above 5000 MPa. • The relationships of elastic constants with mechanical properties were studied. - Abstract: The effects of boron content on the glass-forming ability, mechanical and elastic properties in Co92−xBxTa8 (at.%, x = 30, 32.5, 35, and 37.5) bulk glassy alloys were investigated. Among these alloys studied, the Co59.5B32.5Ta8 alloy exhibits the highest glass-forming ability, which could form a glassy rod at least 3 mm in diameter by the copper mold casting method. It is found that the plasticity of those glassy alloys increases with decreasing boron content. The plastic strains for the Co59.5B32.5Ta8 and Co62B30Ta8 BMGs are up to ∼2.1% and ∼2.5%, respectively. The decrease of shear modulus with decreasing boron content results in the increase of Poisson’s ratio, which is responsible for the improved plasticity. In addition, the strength of the ductile glassy alloys remains very high at above 5000 MPa, although enhancing plasticity is accompanied by the loss of some strength. The present results show that Co–B–Ta bulk metallic glass with good glass-forming ability and significant plasticity as well as ultrahigh strength can be synthesized by adjusting alloy composition

  9. Disruption of urogenital biofilms by lactobacilli.

    Science.gov (United States)

    McMillan, Amy; Dell, Melissa; Zellar, Michelle P; Cribby, Sarah; Martz, Sarah; Hong, Emilio; Fu, Jennifer; Abbas, Ahmed; Dang, Thien; Miller, Wayne; Reid, Gregor

    2011-08-01

    The process that changes a relatively sparse vaginal microbiota of healthy women into a dense biofilm of pathogenic and potentially pathogenic bacteria is poorly understood. Likewise, the reverse step whereby an aberrant biofilm is displaced and returns to a healthy lactobacilli dominated microbiota is unclear. In order to study these phenomena, in vitro experiments were performed to examine the structure of biofilms associated with aerobic vaginosis, urinary tract infections, and bacterial vaginosis (BV). Uropathogenic Escherichia coli were able to form relatively thin biofilms within five days (6 μm height), while Atopobium vaginae and Gardnerella vaginalis formed thicker biofilms 12 μm in height within two days. Challenge of E. coli biofilms with lactobacilli did not result in pathogen displacement. However, the resulting thicker lactobacilli infused biofilms, caused significant E. coli killing. E. coli biofilms challenged with secreted products of L. rhamnosus GR-1 caused a marked decrease in cell density, and increased cell death. Similarly challenge of BV biofilms with lactobacilli infiltrated BV biofilms and caused bacterial cell death. Metronidazole produced holes in the biofilm but did not eradicate the organisms. The findings provide some evidence of how lactobacilli probiotics might interfere with an aberrant vaginal microbiota, and strengthen the position that combining probiotics with antimicrobials could better eradicate pathogenic biofilms. PMID:21497071

  10. Chemical sanitizers to control biofilms formed by two Pseudomonas species on stainless steel surface Sanificantes químicos no controle de biofilmes formados por duas espécies de Pseudomonas em superfície de aço inoxidável

    OpenAIRE

    Danila Soares Caixeta; Thiago Henrique Scarpa; Danilo Florisvaldo Brugnera; Dieyckson Osvani Freire; Eduardo Alves; Luiz Ronaldo de Abreu; Roberta Hilsdorf Piccoli

    2012-01-01

    The biofilm formation of Pseudomonas aeruginosa and Pseudomonas fluorescens on AISI 304 stainless steel in the presence of reconstituted skim milk under different temperatures was conducted, and the potential of three chemical sanitizers in removing the mono-species biofilms formed was compared. Pseudomonas aeruginosa cultivated in skim milk at 28 °C presented better growth rate (10.4 log CFU.mL-1) when compared with 3.7 and 4.2 log CFU.mL-1 for P. aeruginosa and P. fluorescens cultivated at ...

  11. The glass-forming ability of model metal-metalloid alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Kai; Liu, Yanhui; Schroers, Jan [Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06520 (United States); Center for Research on Interface Structures and Phenomena, Yale University, New Haven, Connecticut 06520 (United States); Shattuck, Mark D. [Department of Physics and Benjamin Levich Institute, The City College of the City University of New York, New York, New York 10031 (United States); Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06520 (United States); O’Hern, Corey S. [Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06520 (United States); Center for Research on Interface Structures and Phenomena, Yale University, New Haven, Connecticut 06520 (United States); Department of Physics, Yale University, New Haven, Connecticut 06520 (United States); Department of Applied Physics, Yale University, New Haven, Connecticut 06520 (United States)

    2015-03-14

    Bulk metallic glasses (BMGs) are amorphous alloys with desirable mechanical properties and processing capabilities. To date, the design of new BMGs has largely employed empirical rules and trial-and-error experimental approaches. Ab initio computational methods are currently prohibitively slow to be practically used in searching the vast space of possible atomic combinations for bulk glass formers. Here, we perform molecular dynamics simulations of a coarse-grained, anisotropic potential, which mimics interatomic covalent bonding, to measure the critical cooling rates for metal-metalloid alloys as a function of the atomic size ratio σ{sub S}/σ{sub L} and number fraction x{sub S} of the metalloid species. We show that the regime in the space of σ{sub S}/σ{sub L} and x{sub S} where well-mixed, optimal glass formers occur for patchy and LJ particle mixtures, coincides with that for experimentally observed metal-metalloid glass formers. Thus, our simple computational model provides the capability to perform combinatorial searches to identify novel glass-forming alloys.

  12. The effects of mycoplasma contamination upon the ability to form bioengineered 3D kidney cysts.

    Directory of Open Access Journals (Sweden)

    Teresa M DesRochers

    Full Text Available Mycoplasma contamination of cell cultures is a pervasive, often undiagnosed and ignored problem in many laboratories that can result in reduced cell proliferation and changes in gene expression. Unless contamination is specifically suspected, it is often undetected in two dimensional (2D cultures and the resulting effects of mycoplasma contamination are rarely appreciated and can lead to incorrect conclusions. Three dimensional (3D tissue cultures are increasingly utilized to explore tissue development and phenotype. However, 3D cultures are more complex than 2D cell cultures and require a more controlled cellular environment in order to generate structures necessary to mimic in vivo responses and are often maintained for longer time periods. Changes to the microenvironment are assumed to have a more extreme effect upon the success of 3D tissue cultures than 2D cell cultures, but the effects of mycoplasma have not been studied. To test this hypothesis, we grew 2D cell cultures and 3D tissues from pig kidney epithelial cells (LLC-PK1 that were contaminated with mycoplasma and the same stock of cells after mycoplasma removal. We did not observe an effect of mycoplasma contamination on proliferation in 2D monolayer cell culture. However, cyst formation in 3D tissues was altered, with effects upon the number, size and structure of cysts formed. These data serve to reinforce the necessity of testing cell stocks for mycoplasma contamination.

  13. The glass-forming ability of model metal-metalloid alloys

    International Nuclear Information System (INIS)

    Bulk metallic glasses (BMGs) are amorphous alloys with desirable mechanical properties and processing capabilities. To date, the design of new BMGs has largely employed empirical rules and trial-and-error experimental approaches. Ab initio computational methods are currently prohibitively slow to be practically used in searching the vast space of possible atomic combinations for bulk glass formers. Here, we perform molecular dynamics simulations of a coarse-grained, anisotropic potential, which mimics interatomic covalent bonding, to measure the critical cooling rates for metal-metalloid alloys as a function of the atomic size ratio σS/σL and number fraction xS of the metalloid species. We show that the regime in the space of σS/σL and xS where well-mixed, optimal glass formers occur for patchy and LJ particle mixtures, coincides with that for experimentally observed metal-metalloid glass formers. Thus, our simple computational model provides the capability to perform combinatorial searches to identify novel glass-forming alloys

  14. Changes in CoNS biofilm formation, composition, structure and antimicrobial resistance due to growth in sub-inhibitory concentrations of dicloxacillin

    OpenAIRE

    Cerca, Nuno; Martins, Silvia; Sillankorva, Sanna; Pier, Gerald B.; Oliveira, Rosário; Azeredo, Joana

    2004-01-01

    Many studies have demonstrated that low concentrations of antibiotics can inhibit microbial adherence to medical-device surfaces. However, little is known about the changes that might occur in bacterial physiology of biofilms formed under sub-inhibitory (sub-MIC) concentrations of antibiotics. In this study, biofilms of two coagulase negative staphylococci (CoNS) species were formed with and without the presence of subMIC concentrations of dicloxacillin and changes in the ability to produce b...

  15. Experimental evolution in biofilm populations.

    Science.gov (United States)

    Steenackers, Hans P; Parijs, Ilse; Foster, Kevin R; Vanderleyden, Jozef

    2016-05-01

    Biofilms are a major form of microbial life in which cells form dense surface associated communities that can persist for many generations. The long-life of biofilm communities means that they can be strongly shaped by evolutionary processes. Here, we review the experimental study of evolution in biofilm communities. We first provide an overview of the different experimental models used to study biofilm evolution and their associated advantages and disadvantages. We then illustrate the vast amount of diversification observed during biofilm evolution, and we discuss (i) potential ecological and evolutionary processes behind the observed diversification, (ii) recent insights into the genetics of adaptive diversification, (iii) the striking degree of parallelism between evolution experiments and real-life biofilms and (iv) potential consequences of diversification. In the second part, we discuss the insights provided by evolution experiments in how biofilm growth and structure can promote cooperative phenotypes. Overall, our analysis points to an important role of biofilm diversification and cooperation in bacterial survival and productivity. Deeper understanding of both processes is of key importance to design improved antimicrobial strategies and diagnostic techniques. PMID:26895713

  16. Neuroticism and self-evaluation measures are related to the ability to form cognitive maps critical for spatial orientation.

    Science.gov (United States)

    Burles, Ford; Guadagni, Veronica; Hoey, Felecia; Arnold, Aiden E G F; Levy, Richard M; O'Neill, Thomas; Iaria, Giuseppe

    2014-09-01

    Trait neuroticism is suggested to be related to measures of volume and function of the hippocampus, a brain structure located in the medial temporal lobe that is critical for human navigation and orientation. In this study, we assessed whether measures of trait neuroticism and self-concept are correlated with the human ability to orient by means of cognitive maps (i.e. mental representations of an environment that include landmarks and their spatial relationships). After controlling for gender differences, which are well-known in spatial orientation abilities, we found that measures of neuroticism (i.e. negative affect, emotional stability) and self-concept (i.e. self-esteem) were correlated with individual differences in the rate at which cognitive maps were formed; the same measures were generally unrelated to the ability to make use of cognitive maps, as well as the ability to orient using visual path integration. The relationships (and lack thereof) between personality traits and the spatial orientation skills, as reported in the present study, are consistent with specific neural correlates underlying these factors, and may have important implications for treatment of disorders related to them. PMID:24914460

  17. Microscopic insight into the origin of enhanced glass-forming ability of metallic melts on micro-alloying

    International Nuclear Information System (INIS)

    Extensive efforts have been made to develop metallic-glasses with large casting diameter. Such efforts were hindered by the poor understanding of glass formation mechanisms and the origin of the glass-forming ability (GFA) in metallic glass-forming systems. In this work, we have investigated relaxation dynamics of a model bulk glass-forming alloy system that shows the enhanced at first and then diminished GFA on increasing the percentage of micro-alloying. The micro-alloying did not have any significant impact on the thermodynamic properties. The GFA increasing on micro-alloying in this system cannot be explained by the present theoretical knowledge. Our results indicate that atomic caging is the primary factor that influences the GFA. The composition dependence of the atomic caging time or residence time is found to be well correlated with GFA of the system

  18. Synthesis, structure and complex forming ability of phosphorylated derivatives of heterocyclic compounds

    International Nuclear Information System (INIS)

    Full text: The derivatives of acids of phosphorus, due to variety of properties, are a subject of numerous researches. Now it is known, that the derivatives of acids of phosphorus apart from insect, neurotoxic, antienzym and other kinds of physiological activity have also complex forming properties. As extra gents of noble metals particularly are analyzed by the derivatives of dithio phosphor of acids although organ phosphorus compounds with one nuclear of sulfur make extraction properties. Therefore, with the purpose of detection of effective extra gents of ions of argentum the phosphorylated derivatives of heterogeneous ring compounds were synthesized: Ph(RO)P(O)Cl + HOCH(CH3)CH2-R'-> Ph(RO)P(O)OCH(CH3)CH2-R' + HCl. R C2H5 - C6H13, R' = a piperidine, morpholine, anabasine Structure of the obtained connections is confirmed by the results IR -, Pm- and mass- spectrometry. In an IR-spectrum O-hexyl-O - [piperidynoisopropyl] phenylphosphonate has lines of absorption bands of the following functional groups (ν, cm-1): (P-O-C5H11) 990-1000, (P = 0) 1260, (P-C6H5)1450, (C-N in cycle) 1550. In an IR-spectrum O-pentyl-[anabasinoisopropyl] phenylphosphonate has lines of absorption bands of the following functional groups (ν, cm-1): (P-O-C5H11) 990-1000, (P = 0) 1250, (P-C6H5)1450, (C-N in cycle) 1550. In a spectrum PMR about O-pentyl-[morpholyniisopropyl] phenylphosphonate in the field of a weak field (7, 18-7, 29 p.m.) the multiplet about tones of phenyl group is watched. Me tin proton resonate at 4,66 m.d.as multiplet The signals O-CH2 of protons of morpholinic cycle appear at 3,58 m.d.. 4H) by the way of triplet. The protons N-CH2 (6H) three methylene groups will derivate a composite multiple at 2, 10-2, 70 m.d.. The signal of metil group's protons (3H) is watched at 1,15m.d.as doublet. Final metal group resonates at 0, 87 p.m. Six of C-CH2 of groups give a complex signal in the field of 1, 2-1, 8 m.d. The obtained connections are analyzed as extra gents of ions of

  19. The cabABC Operon Essential for Biofilm and Rugose Colony Development in Vibrio vulnificus.

    Directory of Open Access Journals (Sweden)

    Jin Hwan Park

    2015-09-01

    Full Text Available A transcriptome analysis identified Vibrio vulnificus cabABC genes which were preferentially expressed in biofilms. The cabABC genes were transcribed as a single operon. The cabA gene was induced by elevated 3',5'-cyclic diguanylic acid (c-di-GMP and encoded a calcium-binding protein CabA. Comparison of the biofilms produced by the cabA mutant and its parent strain JN111 in microtiter plates using crystal-violet staining demonstrated that CabA contributed to biofilm formation in a calcium-dependent manner under elevated c-di-GMP conditions. Genetic and biochemical analyses revealed that CabA was secreted to the cell exterior through functional CabB and CabC, distributed throughout the biofilm matrix, and produced as the biofilm matured. These results, together with the observation that CabA also contributes to the development of rugose colony morphology, indicated that CabA is a matrix-associated protein required for maturation, rather than adhesion involved in the initial attachment, of biofilms. Microscopic comparison of the structure of biofilms produced by JN111 and the cabA mutant demonstrated that CabA is an extracellular matrix component essential for the development of the mature biofilm structures in flow cells and on oyster shells. Exogenously providing purified CabA restored the biofilm- and rugose colony-forming abilities of the cabA mutant when calcium was available. Circular dichroism and size exclusion analyses revealed that calcium binding induces CabA conformational changes which may lead to multimerization. Extracellular complementation experiments revealed that CabA can assemble a functional matrix only when exopolysaccharides coexist. Consequently, the combined results suggested that CabA is a structural protein of the extracellular matrix and multimerizes to a conformation functional in building robust biofilms, which may render V. vulnificus to survive in hostile environments and reach a concentrated infective dose.

  20. Relationship of biofilm formation and different virulence genes in uropathogenic Escherichia coli isolates from Northwest Iran

    Directory of Open Access Journals (Sweden)

    Fattahi, Sargol

    2015-07-01

    Full Text Available Background and objectives: The ( bacterium is one of the main causative agents of urinary tract infections (UTI worldwide. The ability of this bacterium to form biofilms on medical devices such as catheters plays an important role in the development of UTI. The aim of the present study was to investigate the possible relationship between virulence factors and biofilm formation of isolates responsible for urinary tract infection.Materials and methods: A total of 100 isolates isolated from patients with UTI were collected and characterized by routine bacteriological methods. In vitro biofilm formation by these isolates was determined using the 96-well microtiter-plate test, and the presence of , , and virulence genes was examined by PCR assay. Data analysis was performed using SPSS 16.0 software.Results: From 100 isolates isolated from UTIs, 92% were shown to be biofilm positive. The genes , , and were detected in 43%, 94% and 26% of isolates, respectively. Biofilm formation in isolates that expressed , , and genes was 100%, 93%, and 100%, respectively. A significant relationship was found between presence of the gene and biofilm formation in isolates isolated from UTI (<0.01, but there was no statistically significant correlation between presence of and genes with biofilm formation (<0.072, <0.104. Conclusion: Results showed that and genes do not seem to be necessary or sufficient for the production of biofilm in , but the presence of correlates with increased biofilm formation of urinary tract isolates. Overall, the presence of , , and virulence genes coincides with in vitro biofilm formation in uropathogenic

  1. Preliminary assessment of the interaction of introduced biological agents with biofilms in water distribution systems.

    Energy Technology Data Exchange (ETDEWEB)

    Sinclair, Michael B.; Caldwell, Sara; Jones, Howland D. T.; Altman, Susan Jeanne; Souza, Caroline Ann; McGrath, Lucas K.

    2005-12-01

    Basic research is needed to better understand the potential risk of dangerous biological agents that are unintentionally or intentionally introduced into a water distribution system. We report on our capabilities to conduct such studies and our preliminary investigations. In 2004, the Biofilms Laboratory was initiated for the purpose of conducting applied research related to biofilms with a focus on application, application testing and system-scale research. Capabilities within the laboratory are the ability to grow biofilms formed from known bacteria or biofilms from drinking water. Biofilms can be grown quickly in drip-flow reactors or under conditions more analogous to drinking-water distribution systems in annular reactors. Biofilms can be assessed through standard microbiological techniques (i .e, aerobic plate counts) or with various visualization techniques including epifluorescent and confocal laser scanning microscopy and confocal fluorescence hyperspectral imaging with multivariate analysis. We have demonstrated the ability to grow reproducible Pseudomonas fluorescens biofilms in the annular reactor with plate counts on the order of 10{sup 5} and 10{sup 6} CFU/cm{sup 2}. Stationary phase growth is typically reached 5 to 10 days after inoculation. We have also conducted a series of pathogen-introduction experiments, where we have observed that both polystyrene microspheres and Bacillus cereus (as a surrogate for B. anthracis) stay incorporated in the biofilms for the duration of our experiments, which lasted as long as 36 days. These results indicated that biofilms may act as a safe harbor for bio-pathogens in drinking water systems, making it difficult to decontaminate the systems.

  2. Biofilm induced tolerance towards antimicrobial peptides.

    Directory of Open Access Journals (Sweden)

    Anders Folkesson

    Full Text Available Increased tolerance to antimicrobial agents is thought to be an important feature of microbes growing in biofilms. We address the question of how biofilm organization affects antibiotic susceptibility. We established Escherichia coli biofilms with differential structural organization due to the presence of IncF plasmids expressing altered forms of the transfer pili in two different biofilm model systems. The mature biofilms were subsequently treated with two antibiotics with different molecular targets, the peptide antibiotic colistin and the fluoroquinolone ciprofloxacin. The dynamics of microbial killing were monitored by viable count determination, and confocal laser microscopy. Strains forming structurally organized biofilms show an increased bacterial survival when challenged with colistin, compared to strains forming unstructured biofilms. The increased survival is due to genetically regulated tolerant subpopulation formation and not caused by a general biofilm property. No significant difference in survival was detected when the strains were challenged with ciprofloxacin. Our data show that biofilm formation confers increased colistin tolerance to cells within the biofilm structure, but the protection is conditional being dependent on the structural organization of the biofilm, and the induction of specific tolerance mechanisms.

  3. Dependence of the initial adhesion of biofilm forming Pseudomonas putida mt2 on physico-chemical material properties.

    Science.gov (United States)

    Montag, Dominik; Frant, Marion; Horn, Harald; Liefeith, Klaus

    2012-01-01

    Bacterial adhesion is strongly dependent on the physico-chemical properties of materials and plays a fundamental role in the development of a growing biofilm. Selected materials were characterized with respect to their physico-chemical surface properties. The different materials, glass and several polymer foils, showed a stepwise range of surface tensions (γ(s)) between 10.3 and 44.7 mN m(-1). Measured zeta potential values were in the range between -74.8 and -28.3 mV. The initial bacterial adhesion parameter q(max) was found to vary between 6.6 × 10(6) and 28.1 × 10(6) cm(-2). By correlation of the initial adhesions kinetic parameters with the surface tension data, the optimal conditions for the immobilization of Pseudomonas putida mt2 were found to be at a surface tension of 24.7 mN m(-1). Both higher and lower surface tensions lead to a smaller number of adherent cells per unit surface area. Higher energy surfaces, commonly termed hydrophilic, could constrain bacterial adhesion because of their more highly ordered water structure (exclusion zone) close to the surface. At low energy surfaces, commonly referred to as hydrophobic, cell adhesion is inhibited due to a thin, less dense zone (depletion layer or clathrate structure) close to the surface. Correlation of q (max) with zeta potential results in a linear relationship. Since P. putida carries weak negative charges, a measurable repulsive effect can be assumed on negative surfaces. PMID:22452391

  4. Pattern formation in Pseudomonas aeruginosa biofilms

    DEFF Research Database (Denmark)

    Parsek, Matthew R.; Tolker-Nielsen, Tim

    2008-01-01

    Bacteria are capable of forming elaborate multicellular communities called biofilms. Pattern formation in biofilms depends on cell proliferation and cellular migration in response to the available nutrients and other external cues, as well as on self-generated intercellular signal molecules and the...... production of an extracellular matrix that serves as a structural 'scaffolding' for the biofilm cells. Pattern formation in biofilms allows cells to position themselves favorably within nutrient gradients and enables buildup and maintenance of physiologically distinct subpopulations, which facilitates...... survival of one or more subpopulations upon environmental insult, and therefore plays an important role in the innate tolerance displayed by biofilms toward adverse conditions....

  5. Investigating the atomic level influencing factors of glass forming ability in NiAl and CuZr metallic glasses

    International Nuclear Information System (INIS)

    Bulk metallic glasses are a relatively new class of amorphous metal alloy which possess unique mechanical and magnetic properties. The specific concentrations and combinations of alloy elements needed to prevent crystallization during melt quenching remains poorly understood. A correlation between atomic properties that can explain some of the previously identified glass forming ability (GFA) anomalies of the NiAl and CuZr systems has been identified, with these findings likely extensible to other transition metal–transition metal and transition metal–metalloid (TM–M) alloy classes as a whole. In this work, molecular dynamics simulation methods are utilized to study thermodynamic, kinetic, and structural properties of equiatomic CuZr and NiAl metallic glasses in an attempt to further understand the underlying connections between glass forming ability, nature of atomic level bonding, short and medium range ordering, and the evolution of structure and relaxation properties in the disordered phase. The anomalous breakdown of the fragility parameter as a useful GFA indicator in TM–M alloy systems is addressed through an in-depth investigation of bulk stiffness properties and the evolution of (pseudo)Gruneisen parameters over the quench domain, with the efficacy of other common glass forming ability indicators similarly being analyzed through direct computation in respective CuZr and NiAl systems. Comparison of fractional liquid-crystal density differences in the two systems revealed 2-3 times higher values for the NiAl system, providing further support for its efficacy as a general purpose GFA indicator

  6. Investigating the atomic level influencing factors of glass forming ability in NiAl and CuZr metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Sedighi, Sina; Kirk, Donald Walter; Singh, Chandra Veer, E-mail: chandraveer.singh@utoronto.ca; Thorpe, Steven John [Department of Materials Science and Engineering, University of Toronto, Room 140, 184 College Street, Toronto, Ontario M5S 3E4 (Canada)

    2015-09-21

    Bulk metallic glasses are a relatively new class of amorphous metal alloy which possess unique mechanical and magnetic properties. The specific concentrations and combinations of alloy elements needed to prevent crystallization during melt quenching remains poorly understood. A correlation between atomic properties that can explain some of the previously identified glass forming ability (GFA) anomalies of the NiAl and CuZr systems has been identified, with these findings likely extensible to other transition metal–transition metal and transition metal–metalloid (TM–M) alloy classes as a whole. In this work, molecular dynamics simulation methods are utilized to study thermodynamic, kinetic, and structural properties of equiatomic CuZr and NiAl metallic glasses in an attempt to further understand the underlying connections between glass forming ability, nature of atomic level bonding, short and medium range ordering, and the evolution of structure and relaxation properties in the disordered phase. The anomalous breakdown of the fragility parameter as a useful GFA indicator in TM–M alloy systems is addressed through an in-depth investigation of bulk stiffness properties and the evolution of (pseudo)Gruneisen parameters over the quench domain, with the efficacy of other common glass forming ability indicators similarly being analyzed through direct computation in respective CuZr and NiAl systems. Comparison of fractional liquid-crystal density differences in the two systems revealed 2-3 times higher values for the NiAl system, providing further support for its efficacy as a general purpose GFA indicator.

  7. Chemical sanitizers to control biofilms formed by two Pseudomonas species on stainless steel surface Sanificantes químicos no controle de biofilmes formados por duas espécies de Pseudomonas em superfície de aço inoxidável

    Directory of Open Access Journals (Sweden)

    Danila Soares Caixeta

    2012-03-01

    Full Text Available The biofilm formation of Pseudomonas aeruginosa and Pseudomonas fluorescens on AISI 304 stainless steel in the presence of reconstituted skim milk under different temperatures was conducted, and the potential of three chemical sanitizers in removing the mono-species biofilms formed was compared. Pseudomonas aeruginosa cultivated in skim milk at 28 °C presented better growth rate (10.4 log CFU.mL-1 when compared with 3.7 and 4.2 log CFU.mL-1 for P. aeruginosa and P. fluorescens cultivated at 7 °C, respectively. Pseudomonas aeruginosa formed biofilm when cultivated at 28 °C. However, only the adhesion of P. aeruginosa and P. fluorescens was observed when incubated at 7 °C. The sodium dichloroisocyanurate was the most efficient sanitizer in the reduction of the adhered P. aeruginosa cells at 7 and 28 °C and those on the biofilm, respectively. The hydrogen peroxide was more effective in the reduction of adhered cells of P. fluorescens at 7 °C.A capacidade de adesão e formação de biofilme por Pseudomonas aeruginosa e Pseudomonas fluorescens em aço inoxidável AISI 304, na presença de leite desnatado resconstituído sobre diferentes temperaturas foi conduzido e o potencial de três sanificantes químicos na remoção de biofilmes monoespécies foi comparado. Pseudomonas aeruginosa cultivada em leite desnatado a 28 °C apresentou melhor crescimento (10,4 log UFC.mL-1 quando comparado com 3,7 and 4,2 log UFC.mL-1 para P. aeruginosa e P. fluorescens cultivadas a 7 °C, respectivamente. Pseudomonas aeruginosa formou biofilme quando cultivada a 28 °C. Contudo foi observado somente adesão de P. aeruginosa e P. fluorescens quando incubada a 7 °C. O dicloroisocianurato de sódio foi o sanificante mais eficiente na redução de células aderidas e em biofilme de P. aeruginosa a 7 e 28 °C, respectivamente. O peróxido de hidrogênio foi o mais eficiente na redução de células aderidas de P. fluorescens a 7 °C.

  8. Pock forming ability of fowl pox virus isolated from layer chicken and its adaptation in chicken embryo fibroblast cell culture

    OpenAIRE

    Varsha Rani Gilhare; Hirpurkar, S. D.; Ashish Kumar; Surendra Kumar Naik; Tarini Sahu

    2015-01-01

    Aim: The objective of the present study was to examine pock forming ability of field strain and vaccine strain of fowl pox virus (FPV) in chorioallantoic membrane (CAM) of embryonated chicken eggs and its adaptation in chicken embryo fibroblast (CEF) cell culture. Materials and Methods: Dry scabs were collected from 25 affected birds in glycerin-saline and preserved at 4°C until processed. Virus was isolated in 10-day-old embryonated chicken eggs by dropped CAM method. The identity of the ...

  9. Unusual glass-forming ability of new Zr-Cu-based bulk glassy alloys containing an immiscible element pair

    International Nuclear Information System (INIS)

    We herein report the unusual glass-forming ability (GFA) of a new series of quinary Zr48Cu36-xNixAg8Al8 (048Cu36Ag8Al8 alloy. By cooper mold casting, an as-cast glassy rod with a diameter of 30 mm can be easily obtained for the representative alloy Zr48Cu32Ni4Ag8Al8. The possible reasons for the excellent GFA of the new quinary alloys with an immiscible element pair are discussed based on the atomic size distribution, chemical compatibility among the components and atomic structure of glassy alloys. (author)

  10. Biofilm formation in clinical isolates of nosocomial Acinetobacter baumannii and its relationship with multidrug resistance

    Institute of Scientific and Technical Information of China (English)

    Ebrahim Babapour; Azam Haddadi; Reza Mirnejad; Seyed-Abdolhamid Angaji; Nour Amirmozafari

    2016-01-01

    Objective: To check biofilm formation by Acinetobacter baumannii (A. baumannii) clinical isolates and show their susceptibility to different antibiotics and investigate a possible link between establishment of biofilm and multidrug resistance. Methods: This study was performed on clinical samples collected from patients with nosocomial infections in three hospitals of Tehran. Samples were initially screened by culture and biochemical tests for the presence of different species of Acinetobacter. Iden-tifications were further confirmed by PCR assays. Their susceptibilities to 11 antibiotics of different classes were determined by disc diffusion method according to Clinical and Laboratory Standards Institute guidelines. The ability to produce biofilm was investigated using methods:culture on Congo red agar, microtiter plate, and test tube method. Results: From the overall clinical samples, 156 specimens were confirmed to contain A. baumannii. The bacteria were highly resistant to most antibiotics except polymyxin B. Of these isolates, 10.26% were able to produce biofilms as shown on Congo red agar. However, the percentage of bacteria with positive biofilm in test tube, standard microtiter plate, and modified microtiter plate assays were 48.72%, 66.66%, and 73.72%, respec-tively. At least 92%of the biofilm forming isolates were multidrug resistant. Conclusions: Since most of the multidrug resistant strains produce biofilm, it seems necessary to provide continuous monitoring and determination of antibiotic susceptibility of clinical A. baumannii. This would help to select the most appropriate antibiotic for treatment.

  11. Outer membrane protein OmpQ of Bordetella bronchiseptica is required for mature biofilm formation.

    Science.gov (United States)

    Cattelan, Natalia; Villalba, María Inés; Parisi, Gustavo; Arnal, Laura; Serra, Diego Omar; Aguilar, Mario; Yantorno, Osvaldo

    2016-02-01

    Bordetella bronchiseptica, an aerobic Gram-negative bacterium, is capable of colonizing the respiratory tract of diverse animals and chronically persists inside the hosts by forming biofilm. Most known virulence factors in Bordetella species are regulated by the BvgAS two-component transduction system. The Bvg-activated proteins play a critical role during host infection. OmpQ is an outer membrane porin protein which is expressed under BvgAS control. Here, we studied the contribution of OmpQ to the biofilm formation process by B. bronchiseptica. We found that the lack of expression of OmpQ did not affect the growth kinetics and final biomass of B. bronchiseptica under planktonic growth conditions. The ΔompQ mutant strain displayed no differences in attachment level and in early steps of biofilm formation. However, deletion of the ompQ gene attenuated the ability of B. bronchiseptica to form a mature biofilm. Analysis of ompQ gene expression during the biofilm formation process by B. bronchiseptica showed a dynamic expression pattern, with an increase of biofilm culture at 48 h. Moreover, we demonstrated that the addition of serum anti-OmpQ had the potential to reduce the biofilm biomass formation in a dose-dependent manner. In conclusion, we showed for the first time, to the best of our knowledge, evidence of the contribution of OmpQ to a process of importance for B. bronchiseptica pathobiology. Our results indicate that OmpQ plays a role during the biofilm development process, particularly at later stages of development, and that this porin could be a potential target for strategies of biofilm formation inhibition. PMID:26673448

  12. Influence of Y, Gd and Sm on the glass forming ability and thermal crystallization of aluminum based alloy

    International Nuclear Information System (INIS)

    Al-based amorphous alloys represent an important family of metals and a great scientific activity has been devoted to determine the main features of both glass forming ability (GFA) and crystallization behavior in order to have a comprehensive framework aimed at potential technological applications. Nowadays, it is well known that the best Al-based amorphous alloys are formed in ternary systems such as Al- RE-TM, where RE is a rare earth and TM a transition metal. This paper presents results of research in Al85Ni10RE5 alloys (RE = Y, Gd and Sm). Amorphous ribbons were processed by melt-spinning under the same conditions and subsequently characterized by x-ray diffraction (XRD) and differential scanning calorimetry (DSC). Results show appreciable micro structural differences as function of the rare earth, thus crystal is obtained for Y, nano-glassy for Gd and, fully amorphous structure for Sm. (author)

  13. Self-appraisal adequacy of students’ physical abilities of pedagogical specialties involved in various forms of education

    Directory of Open Access Journals (Sweden)

    TSYBUL’SKA V.V.

    2014-10-01

    Full Text Available Purpose : considered self-appraisal adequacy of students’ physical abilities of students of pedagogical specialties involved in various forms of education. Material : the study was conducted with students of II and IV courses of the Faculty of Primary Education stationary and correspondence courses (total 120 people.. Used a technique of self-appraisal of physical development, technique of rapid assessment of physical health, motor tests. Results : set the direction for the development of the values of physical culture and self-improvement of physical abilities that depend on the adequacy of the self-assessment of their physical development and physical fitness. The comparison of subjective and objective indicators for assessing physical health and physical fitness of students. Highlighted significant differences in the direction of re-evaluation of their physical abilities in students of correspondence courses. Conclusions : It is recommended to use the self-appraisal methodology of physical development to determine the degree of objectivity of self-confidence, which determines the motivation for self-improvement.

  14. Wound biofilms: lessons learned from oral biofilms

    OpenAIRE

    Mancl, Kimberly A.; Kirsner, Robert S.; Ajdic, Dragana

    2013-01-01

    Biofilms play an important role in the development and pathogenesis of many chronic infections. Oral biofilms, more commonly known as dental plaque,are a primary cause of oral diseases including caries, gingivitis and periodontitis. Oral biofilms are commonly studied as model biofilm systems as they are easily accessible, thus biofilm research in oral diseases is advanced with details of biofilm formation and bacterial interactions being well-elucidated. In contrast, wound research has relati...

  15. Inhibition of Serratia marcescens Smj-11 biofilm formation by Alcaligenes faecalis STN17 crude extract

    Energy Technology Data Exchange (ETDEWEB)

    Lutfi, Zainal; Ahmad, Asmat [School of Biosciences and Biotechnology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia (UKM), 43600 Bangi, Selangor (Malaysia); Usup, Gires [School of Environmental and Natural Resources Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia (UKM), 43600 Bangi, Selangor (Malaysia)

    2014-09-03

    Serratia marcescens biofilms are formed when they are bound to surfaces in aqueous environments. S. marcescens utilizes N-acylhomoserine lactone (AHL) as its quorum sensing signal molecule. The accumulation of AHL indicates the bacteria to produce matrices to form biofilms. Prodigiosin (2-methyl-3-pentyl-6-methoxyprodigiosin), which causes red pigmentation in the colonies, are also produced when the AHL reaches a certain threshold. The Alcaligenes faecalis STN17 crude extract is believed to inhibit quorum sensing in the S. marcescens Smj-11 and, thus, impedes its biofilm formation ability. A. faecalis STN17 was grown in marine broth, and ethyl acetate extraction was carried out. The crude compound of A. faecalis STN17 was diluted at high concentration (0.2-6.4 mg/mL) and was taken to confirm anti-biofilm activity through the crystal violet method in 96-wells plate. Then, the crude extract underwent purification using simple solvents partitioning test to discern the respective compounds that had the anti-biofilm activity under the crystal violet method. The crystal violet test showed that the crude did have anti-biofilm activity on S. marcescens Smj-11, but did not kill the cells. This finding signifies that the suppression of biofilm formation in S. marcescens by A. faecalis STN17 has a strong correlation. The partitioning test showed that A. faecalis STN17 crude extract has several compounds and only the compound(s) in chloroform showed activities. In conclusion, the crude extract of A. faecalis STN17 has the ability to inhibit S. marcescens Smj-11 biofilm formation.

  16. Inhibition of Serratia marcescens Smj-11 biofilm formation by Alcaligenes faecalis STN17 crude extract

    International Nuclear Information System (INIS)

    Serratia marcescens biofilms are formed when they are bound to surfaces in aqueous environments. S. marcescens utilizes N-acylhomoserine lactone (AHL) as its quorum sensing signal molecule. The accumulation of AHL indicates the bacteria to produce matrices to form biofilms. Prodigiosin (2-methyl-3-pentyl-6-methoxyprodigiosin), which causes red pigmentation in the colonies, are also produced when the AHL reaches a certain threshold. The Alcaligenes faecalis STN17 crude extract is believed to inhibit quorum sensing in the S. marcescens Smj-11 and, thus, impedes its biofilm formation ability. A. faecalis STN17 was grown in marine broth, and ethyl acetate extraction was carried out. The crude compound of A. faecalis STN17 was diluted at high concentration (0.2-6.4 mg/mL) and was taken to confirm anti-biofilm activity through the crystal violet method in 96-wells plate. Then, the crude extract underwent purification using simple solvents partitioning test to discern the respective compounds that had the anti-biofilm activity under the crystal violet method. The crystal violet test showed that the crude did have anti-biofilm activity on S. marcescens Smj-11, but did not kill the cells. This finding signifies that the suppression of biofilm formation in S. marcescens by A. faecalis STN17 has a strong correlation. The partitioning test showed that A. faecalis STN17 crude extract has several compounds and only the compound(s) in chloroform showed activities. In conclusion, the crude extract of A. faecalis STN17 has the ability to inhibit S. marcescens Smj-11 biofilm formation

  17. The biofilm matrix destabilizers, EDTA and DNaseI, enhance the susceptibility of nontypeable Hemophilus influenzae biofilms to treatment with ampicillin and ciprofloxacin

    OpenAIRE

    Cavaliere, Rosalia; Ball, Jessica L; Turnbull, Lynne; Whitchurch, Cynthia B.

    2014-01-01

    Nontypeable Hemophilus influenzae (NTHi) is a Gram-negative bacterial pathogen that causes chronic biofilm infections of the ears and airways. The biofilm matrix provides structural integrity to the biofilm and protects biofilm cells from antibiotic exposure by reducing penetration of antimicrobial compounds into the biofilm. Extracellular DNA (eDNA) has been found to be a major matrix component of biofilms formed by many species of Gram-positive and Gram-negative bacteria, including NTHi. In...

  18. Effect of remelting treatment on glass forming ability of RE (Gd, Sm)56Al26Co18 alloys

    International Nuclear Information System (INIS)

    Highlights: • The remelting treatment can improve the GFA for Sm-based and Gd-based BMGs. • The remelting treatment can promote formation of BMGs. • The remelting treatment can enhance the thermal stability of BMGs. -- Abstract: The bulk metallic glasses (BMGs) were prepared by a copper mold suction casting method, denoted by Gd56Al26Co18 (1) and Sm56Al26Co18 (1). Then, the obtained metallic glasses mentioned above were remelted and injected to copper mold, and the metallic glasses were prepared by remelting, denoted by Gd56Al26Co18 (2) and Sm56Al26Co18 (2). The glass forming ability and thermal expansion behavior were investigated by X-ray diffraction (XRD), differential scanning calorimetry (DSC), dilatometer and high resolution transmission electron microscopy (HRTEM). The results showed that the remelting treatment can improve the glass forming ability of the alloys. In addition, it was found that the average thermal expansion coefficients of the BMGs prepared by remelting were smaller than the BMGs prepared by first-time melting for Gd56Al26Co18 and Sm56Al26Co18 alloys, which indicated the remelting treatment can enhance the thermal stability of the Gd56Al26Co18 and Sm56Al26Co18 BMGs

  19. Effect of Ga substitution on the crystallization behaviour and glass forming ability of Zr-Al-Cu-Ni alloys

    International Nuclear Information System (INIS)

    The crystallization behaviour of melt spun Zr69.5Al7.5-xGaxCu12Ni11 (x = 0-7.5; in at.%) metallic glasses has been investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The DSC traces showed changes in crystallization behaviour with substitution of Ga. Formation of single nano-quasicrystalline phase by controlled crystallization of glasses has been found only for 0 ≤ x ≤ 1.5. Further increase of Ga content gives rise to formation of the quasicrystals together with Zr2Cu type crystalline phase. In addition to this, the substitution of Ga influences the size and shape of nano-quasicrystals. The glass forming abilities (GFAs) of these metallic glasses were assessed by the recognition of glass forming ability indicators, i.e. reduced glass transition temperature (Trg) and supercooled liquid region (ΔTx). The glass transition temperature (Tg) has been observed for all the melt spun ribbons.

  20. Glass Forming Ability and Magnetic Property of Fe74Al4Sn2(PSiB)20 Amorphous Alloy

    Institute of Scientific and Technical Information of China (English)

    CHEN Fei-fei; ZHOU Shao-xiong

    2004-01-01

    Amorphous ribbons of Fe74Al4Sn2(PSiB)20 alloy have been synthesized by melt spinning and axial design method. The thermal properties of the amorphous ribbons have been measured by differential scanning calorimeter (DSC). The DSC results show that the Fe74Al4Sn2P12Si4B4 amorphous alloy has relatively wider supercooled liquid region with a temperature interval of 40.38 K (ΔTx=Tx-Tg). The alloys with a higher phosphorous content in the metalloid element composition triangle of Fe74Al4Sn2(PSiB)20 have high glass forming ability. The amorphous alloys also show good magnetic properties in which Fe74Al4Sn2P6.67Si6.67B6.67 alloy has a large maximum permeability (μm), Fe78Al4Sn2P3Si3B10 alloy exhibits a high square ratio (Br/B10) and Fe74Al4Sn2P4Si12B4 shows a low core loss (P0.5/1.3T). High glass forming ability and good magnetic properties make Fe74Al4Sn2(PSiB)20 amorphous alloys valuable in future research.

  1. A new Ti-Zr-Hf-Cu-Ni-Si-Sn bulk amorphous alloy with high glass-forming ability

    International Nuclear Information System (INIS)

    The effect of Sn substitution for Cu on the glass-forming ability was investigated in Ti41.5Zr2.5Hf5Cu42.5-xNi7.5Si1Sn x (x = 0, 1, 3, 5, 7) alloys by using differential scanning calorimetry (DSC) and X-ray diffractometry. The alloy containing 5% Sn shows the highest glass-forming ability (GFA) among the Ti-Zr-Hf-Cu-Ni-Si-Sn system. Fully amorphous rod sample with diameters up to 6 mm could be successfully fabricated by the copper mold casting Ti41.5Zr2.5Hf5Cu37.5Ni7.5Si1Sn5 alloy. The activation energies for glass transition and crystallization for Ti41.5Zr2.5Hf5Cu37.5Ni7.5Si1Sn5 amorphous alloy are both larger than those values for the Sn-free alloy. The enhancement in GFA and thermal stability after the partial replacement of Cu by Sn may be contributed to the strong atomic bonding nature between Ti and Sn and the increasing of atomic packing density. The amorphous Ti41.5Zr2.5Hf5Cu37.5Ni7.5Si1Sn5 alloy also possesses superior mechanical properties

  2. Influence of Si on glass forming ability and properties of the bulk amorphous alloy Mg60Cu30Y10

    International Nuclear Information System (INIS)

    Research highlights: → The partial substitution of Cu by the right amount of Si increases the glass forming ability of the bulk amorphous alloy Mg60Cu30Y10. → The serrations size of Mg60Cu30-xY10Six is dependent on the content of Si. → The creep displacement of Mg60Cu30-xY10Six alloys decrease with increasing Si content. → The elastic modulus and nano-hardness of Mg60Cu30-xY10Six are dependent on the Si content. - Abstract: We studied the influence of partially replacing Cu by Si in the bulk amorphous alloy Mg30Cu30Y10. Glass forming ability (GFA), examined using X-ray diffraction and a differential scanning calorimeter, was increased at 1% Si, but decreased for larger Si concentrations. Nano-indentation measured nano-hardness, elastic modulus and load-displacement curves. The elastic modulus and nano-hardness increased with increasing Si content to a maximum at 2.5%. The load-displacement curves during nano-indentation revealed displacement serrations. These increased with decreasing loading rates, decreased with increasing Si content. The load-displacement curves also indicated that these bulk amorphous alloys exhibited primary creep at room temperature just like other high strength alloys. The creep displacement decreased with increasing Si content.

  3. Apatite-forming ability of vinylphosphonic acid-based copolymer in simulated body fluid: effects of phosphate group content.

    Science.gov (United States)

    Hamai, Ryo; Shirosaki, Yuki; Miyazaki, Toshiki

    2016-10-01

    Phosphate groups on materials surfaces are known to contribute to apatite formation upon exposure of the materials in simulated body fluid and improved affinity of the materials for osteoblast-like cells. Typically, polymers containing phosphate groups are organic matrices consisting of apatite-polymer composites prepared by biomimetic process using simulated body fluid. Ca(2+) incorporation into the polymer accelerates apatite formation in simulated body fluid owing because of increase in the supersaturation degree, with respect to apatite in simulated body fluid, owing to Ca(2+) release from the polymer. However, the effects of phosphate content on the Ca(2+) release and apatite-forming abilities of copolymers in simulated body fluid are rather elusive. In this study, a phosphate-containing copolymer prepared from vinylphosphonic acid, 2-hydroxyethyl methacrylate, and triethylene glycol dimethacrylate was examined. The release of Ca(2+) in Tris-NaCl buffer and simulated body fluid increased as the additive amount of vinylphosphonic acid increased. However, apatite formation was suppressed as the phosphate groups content increased despite the enhanced release of Ca(2+) from the polymer. This phenomenon was reflected by changes in the surface zeta potential. Thus, it was concluded that the apatite-forming ability of vinylphosphonic acid-2-hydroxyethyl methacrylate-triethylene glycol dimethacrylate copolymer treated with CaCl2 solution was governed by surface state rather than Ca(2+) release in simulated body fluid. PMID:27585911

  4. Comparison of antimicrobial efficacy of propolis, Morinda citrifolia, Azadirachta indica (Neem and 5% sodium hypochlorite on Candida albicans biofilm formed on tooth substrate: An in-vitro study

    Directory of Open Access Journals (Sweden)

    Shashi Prabha Tyagi

    2013-01-01

    Full Text Available Introduction: Endodontic infections are polymicrobial in nature. Candida albicans is the most common fungus isolated from failed endodontic cases. The constant increase in antibiotic resistant strains and side-effects caused by synthetic drugs has prompted researchers to look for herbal alternatives such as propolis, Morinda citrifolia and Azadirachta indica (Neem etc., since, the gold standard for irrigation, i.e., sodium hypochlorite has many disadvantages. Materials and Methods: Extracted human mandibular premolars were biomechanically prepared, vertically sectioned, placed in tissue culture wells exposing the root canal surface to C. albicans grown on Sabouraud Dextrose Agar to form a biofilm. At the end of 2 days, all groups were treated with test solutions and control for 10 min and evaluated for Candida growth and number of colony forming units. The readings were subjected to statistical analysis using analysis of variance and post hoc Tukey tests. Results: Sodium hypochlorite and propolis groups exhibited highest antimicrobial efficacy against C. albicans with no statistically significant difference. It was followed by the A. indica (Neem group. M. citrifolia had limited antifungal action followed by the negative control group of saline. Conclusion: According to the results of this study, propolis can be used as an effective antifungal agent similar to that of sodium hypochlorite, although long-term in vivo studies are warranted.

  5. Alginate production affects Pseudomonas aeruginosa biofilm development and architecture, but is not essential for biofilm formation

    DEFF Research Database (Denmark)

    Stapper, A.P.; Narasimhan, G.; Oman, D.E.;

    2004-01-01

    Extracellular polymers can facilitate the non-specific attachment of bacteria to surfaces and hold together developing biofilms. This study was undertaken to qualitatively and quantitatively compare the architecture of biofilms produced by Pseudomonas aeruginosa strain PAO1 and its alginate...... biofilm formation using confocal laser scanning microscopy. Biofilm Image Processing (BIP) and Community Statistics (COMSTAT) software programs were used to provide quantitative measurements of the two-dimensional biofilm images. All three strains formed distinguishable biofilm architectures, indicating...... that the production of alginate is not critical for biofilm formation. Observation over a period of 5 days indicated a three-stage development pattern consisting of initiation, establishment and maturation. Furthermore, this study showed that phenotypically distinguishable biofilms can be...

  6. Lipopeptides from Bacillus strain AR2 inhibits biofilm formation by Candida albicans.

    Science.gov (United States)

    Rautela, Ria; Singh, Anil Kumar; Shukla, Abha; Cameotra, Swaranjit Singh

    2014-05-01

    The ability of the human fungal pathogen Candida albicans to reversibly switch between different morphological forms and establish biofilms is crucial for establishing infection. Targeting phenotypic plasticity and biofilm formation in C. albicans represents a new concept for antifungal drug discovery. The present study evaluated the influence of cyclic lipopeptide biosurfactant produced by Bacillus amyloliquefaciens strain AR2 on C. albicans biofilms. The biosurfactant was characterized as a mixture of iturin and fengycin by MALDI-TOF and amino acid analysis. The biosurfactant exhibited concentration dependent growth inhibition and fungicidal activity. The biosurfactant at sub-minimum growth inhibition concentration decreased cell surface hydrophobicity, hindered germ tube formation and reduced the mRNA expression of hyphae-specific gene HWP1 and ALS3 without exhibiting significant growth inhibition. The biosurfactants inhibited biofilm formation in the range of 46-100 % depending upon the concentration and Candida strains. The biosurfactant treatment dislodged 25-100 % of preformed biofilm from polystyrene plates. The biosurfactant retained its antifungal and antibiofilm activity even after exposure to extreme temperature. By virtue of the ability to inhibit germ tube and biofilm formation, two important traits of C. albicans involved in establishing infection, lipopeptides from strain AR2 may represent a potential candidate for developing heat stable anti-Candida drugs. PMID:24623107

  7. Iron and Pseudomonas aeruginosa biofilm formation

    OpenAIRE

    Banin, Ehud; Vasil, Michael L.; Greenberg, E. Peter

    2005-01-01

    Iron serves as a signal in Pseudomonas aeruginosa biofilm development. We examined the influence of mutations in known and putative iron acquisition-signaling genes on biofilm morphology. In iron-sufficient medium, mutants that cannot obtain iron through the high-affinity pyoverdine iron acquisition system form thin biofilms similar to those formed by the parent under low iron conditions. If an iron source for a different iron acquisition system is provided to a pyoverdine mutant, normal biof...

  8. Functional bacterial amyloid increases Pseudomonas biofilm hydrophobicity and stiffness

    DEFF Research Database (Denmark)

    Zeng, Guanghong; Vad, Brian Stougaard; Dueholm, Morten Simonsen;

    2015-01-01

    and increases biofilm stiffness 20-fold. Deletion of any one of the individual members of in the fap operon (except the putative chaperone FapA) abolishes this ability to increase biofilm stiffness and correlates with the loss of amyloid. We conclude that amyloid makes major contributions to biofilm...

  9. Modelling the growth of a methanotrophic biofilm

    DEFF Research Database (Denmark)

    Arcangeli, J.-P.; Arvin, E.

    1999-01-01

    This article discusses the growth of methanotrophic biofilms. Several independent biofilm growths scenarios involving different inocula were examined. Biofilm growth, substrate removal and product formation were monitored throughout the experiments. Based on the oxygen consumption it was concluded...... that heterotrophs and nitrifiers co-existed with methanotrophs in the biofilm. Heterotrophic biomass grew on soluble polymers formed by the hydrolysis of dead biomass entrapped in the biofilm. Nitrifier populations developed because of the presence of ammonia in the mineral medium. Based on these...... analysis was performed on this model. It indicated that the most influential parameters were those related to the biofilm (i.e. density; solid-volume fraction; thickness). This suggests that in order to improve the model, further research regarding the biofilm structure and composition is needed....

  10. Intrigues of biofilm: A perspective in veterinary medicine

    OpenAIRE

    Umar Faruk Abdullahi; Ephraim Igwenagu; Anas Mu’azu; Sani Aliyu; Maryam Ibrahim Umar

    2016-01-01

    Biofilm has a tremendous impact in the field of veterinary medicine, especially the livestock industry, leading to a serious economic loss. Over the years, little attention has been given to biofilm in animals with most of the research geared toward human biofilm diseases. The greatest challenge posed by biofilm is in its incredible ability to resist most of the currently existing antibiotics. This mystery can best be demystified through understanding the mechanism of the quorum sensing which...

  11. Microspatial variation in marine biofilm abundance on intertidal rock surfaces

    OpenAIRE

    Aitchison, JC; Williams, GA; Hutchinson, N; Nagarkar, S

    2006-01-01

    The effect of substrate surface roughness on small-scale patchiness and the ability of molluscan grazers to feed on intertidal biofilms was examined in a factorial experiment. Granite slabs were treated to create 4 different levels of surface roughness, and biofilm and macroalgae were allowed to recruit. Biofilm cover varied greatly with slab roughness, and was spatially patchy at a scale of millimetres. Diatoms dominated the biofilm, but were less abundant on surfaces with the smallest pits....

  12. Analysis of the role of the LH92_11085 gene of a biofilm hyper-producing Acinetobacter baumannii strain on biofilm formation and attachment to eukaryotic cells.

    Science.gov (United States)

    Álvarez-Fraga, Laura; Pérez, Astrid; Rumbo-Feal, Soraya; Merino, María; Vallejo, Juan Andrés; Ohneck, Emily J; Edelmann, Richard E; Beceiro, Alejandro; Vázquez-Ucha, Juan C; Valle, Jaione; Actis, Luis A; Bou, Germán; Poza, Margarita

    2016-05-18

    Acinetobacter baumannii is a nosocomial pathogen that has a considerable ability to survive in the hospital environment partly due to its capacity to form biofilms. The first step in the process of establishing an infection is adherence of the bacteria to target cells. Chaperone-usher pili assembly systems are involved in pilus biogenesis pathways that play an important role in adhesion to host cells and tissues as well as medically relevant surfaces. After screening a collection of strains, a biofilm hyper-producing A. baumannii strain (MAR002) was selected to describe potential targets involved in pathogenicity. MAR002 showed a remarkable ability to form biofilm and attach to A549 human alveolar epithelial cells. Analysis of MAR002 using transmission electron microscopy (TEM) showed a significant presence of pili on the bacterial surface. Putative protein-coding genes involved in pili formation were identified based on the newly sequenced genome of MAR002 strain (JRHB01000001/2 or NZ_JRHB01000001/2). As assessed by qRT-PCR, the gene LH92_11085, belonging to the operon LH92_11070-11085, is overexpressed (ca. 25-fold more) in biofilm-associated cells compared to exponential planktonic cells. In the present work we investigate the role of this gene on the MAR002 biofilm phenotype. Scanning electron microscopy (SEM) and biofilm assays showed that inactivation of LH92_11085 gene significantly reduced bacterial attachment to A549 cells and biofilm formation on plastic, respectively. TEM analysis of the LH92_11085 mutant showed the absence of long pili formations normally present in the wild-type. These observations indicate the potential role this LH92_11085 gene could play in the pathobiology of A baumannii. PMID:26854744

  13. Glass forming ability of binary Ni60+xNb40-x (x=0;1;2 alloys

    Directory of Open Access Journals (Sweden)

    R. Nowosielski

    2010-09-01

    Full Text Available Purpose: This paper presents the investigations results of fabrication and structure tests binary Ni-Nb metallic glasses.Design/methodology/approach: The studies were performed on Ni60+xNb40-x (x=0, 1, 2 alloys in form of ribbon and rods up to 2 mm. For the purpose of fabrication test pieces, melt spinning and pressure die casting methods were used. The main index for determine glass forming ability was thickness of specimens. To the tests of samples structure X-ray diffraction phase analysis (XRD and scanning electron microscopy (SEM were used. Owing to good mechanical properties of Ni-based metallic glasses, microhardness of cast rods were examined.Findings: X-ray diffraction and SEM analysis have revealed that samples in form of ribbons were amorphous, while cast rods were crystalline.Practical implications: The relationship between amorphous structure and good mechanical properties could be promising for many engineering application. The Ni-based bulk metallic glasses are newcomers engineering materials which may be applied to a new type pressure sensor exhibiting higher capability and higher sensitivityOriginality/value: Paper present quite new type of binary metallic glasses based on Ni. For the sake of alloy simplicity it is possible that this alloys will be used in many applications.

  14. Enhancement of glass-forming ability and mechanical behavior of zirconium–lanthanide two-phase bulk metallic glasses

    International Nuclear Information System (INIS)

    Highlights: • This work provides a new concept for design of two-phase BMGs. • The formation of two-glass structure in two-liquid systems is analyzed. • A strategy for improving GFA of two-phase metallic glasses is proposed. • A family of two-phase metallic glasses in bulk form is developed. • The mechanical behavior of two-phase BMGs is studied for the first time. - Abstract: Development of the two-phase bulk metallic glasses (BMGs) is essentially retarded due to difficulties in finding of phase-separated (immiscible) alloys with high glass-forming ability (GFA) of coexistent phases. Referring to the concept of solute partitioning and minimization of free energy, in this work we present an idea that a metallic liquid system containing two liquids with individual self-assembled eutectic composition may yield two-phase BMGs upon casting. The formation of the two-glass structure is discussed and a strategy of partial substitution of chemically similar elements for overcoming the drawback of low GFA is proposed. A family of two-phase zirconium–lanthanide based metallic glasses in bulk form is developed. The mechanical behavior of the two-phase BMGs with different ratio of zirconium-rich to lanthanide-rich glassy phase is studied for the first time. This work provides a new concept for fabrication of two-phase BMGs and reveals the role of constituent phases in determining the mechanical properties of the whole glass

  15. Exopolysaccharides produced by Streptococcus mutans glucosyltransferases modulate the establishment of microcolonies within multispecies biofilms.

    Science.gov (United States)

    Koo, H; Xiao, J; Klein, M I; Jeon, J G

    2010-06-01

    Streptococcus mutans is a key contributor to the formation of the extracellular polysaccharide (EPS) matrix in dental biofilms. The exopolysaccharides, which are mostly glucans synthesized by streptococcal glucosyltransferases (Gtfs), provide binding sites that promote accumulation of microorganisms on the tooth surface and further establishment of pathogenic biofilms. This study explored (i) the role of S. mutans Gtfs in the development of the EPS matrix and microcolonies in biofilms, (ii) the influence of exopolysaccharides on formation of microcolonies, and (iii) establishment of S. mutans in a multispecies biofilm in vitro using a novel fluorescence labeling technique. Our data show that the ability of S. mutans strains defective in the gtfB gene or the gtfB and gtfC genes to form microcolonies on saliva-coated hydroxyapatite surfaces was markedly disrupted. However, deletion of both gtfB (associated with insoluble glucan synthesis) and gtfC (associated with insoluble and soluble glucan synthesis) is required for the maximum reduction in EPS matrix and biofilm formation. S. mutans grown with sucrose in the presence of Streptococcus oralis and Actinomyces naeslundii steadily formed exopolysaccharides, which allowed the initial clustering of bacterial cells and further development into highly structured microcolonies. Concomitantly, S. mutans became the major species in the mature biofilm. Neither the EPS matrix nor microcolonies were formed in the presence of glucose in the multispecies biofilm. Our data show that GtfB and GtfC are essential for establishment of the EPS matrix, but GtfB appears to be responsible for formation of microcolonies by S. mutans; these Gtf-mediated processes may enhance the competitiveness of S. mutans in the multispecies environment in biofilms on tooth surfaces. PMID:20233920

  16. Reducing Staphylococcus aureus biofilm formation on stainless steel 316L using functionalized self-assembled monolayers

    International Nuclear Information System (INIS)

    Stainless steel 316L (SS316L) is a common material used in orthopedic implants. Bacterial colonization of the surface and subsequent biofilm development can lead to refractory infection of the implant. Since the greatest risk of infection occurs perioperatively, strategies that reduce bacterial adhesion during this time are important. As a strategy to limit bacterial adhesion and biofilm formation on SS316L, self-assembled monolayers (SAMs) were used to modify the SS316L surface. SAMs with long alkyl chains terminated with hydrophobic (− CH3) or hydrophilic (oligoethylene glycol) tail groups were used to form coatings and in an orthogonal approach, SAMs were used to immobilize gentamicin or vancomycin on SS316L for the first time to form an “active” antimicrobial coating to inhibit early biofilm development. Modified SS316L surfaces were characterized using surface infrared spectroscopy, contact angles, MALDI-TOF mass spectrometry and atomic force microscopy. The ability of SAM-modified SS316L to retard biofilm development by Staphylococcus aureus was functionally tested using confocal scanning laser microscopy with COMSTAT image analysis, scanning electron microscopy and colony forming unit analysis. Neither hydrophobic nor hydrophilic SAMs reduced biofilm development. However, gentamicin-linked and vancomycin-linked SAMs significantly reduced S. aureus biofilm formation for up to 24 and 48 h, respectively. - Highlights: ► SS316L was modified with glycol terminated SAMs in order to reduce biofilm growth. ► Antibiotics gentamicin and vancomycin were immobilized on SS316L via SAMs. ► Only the antibiotic modifications reduced biofilm development on SS316L

  17. Reducing Staphylococcus aureus biofilm formation on stainless steel 316L using functionalized self-assembled monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Kruszewski, Kristen M., E-mail: kruszewskik@duq.edu [Duquesne University, Department of Chemistry and Biochemistry, 600 Forbes Avenue, Pittsburgh, PA 15282 (United States); Nistico, Laura, E-mail: lnistico@wpahs.org [Allegheny General Hospital, Center for Genomic Sciences, Allegheny-Singer Research Institute, 320 East North Avenue, 11th floor, South Tower, Pittsburgh, PA 15212 (United States); Longwell, Mark J., E-mail: mlongwel@wpahs.org [Allegheny General Hospital, Center for Genomic Sciences, Allegheny-Singer Research Institute, 320 East North Avenue, 11th floor, South Tower, Pittsburgh, PA 15212 (United States); Hynes, Matthew J., E-mail: mjhynes@go.wustl.edu [Washington University in St. Louis, Department of Chemistry, One Brookings Drive, St. Louis, MO 63130 (United States); Maurer, Joshua A., E-mail: maurer@wustl.edu [Washington University in St. Louis, Department of Chemistry, One Brookings Drive, St. Louis, MO 63130 (United States); Hall-Stoodley, Luanne, E-mail: L.Hall-Stoodley@soton.ac.uk [Southampton Wellcome Trust Clinical Research Facility/NIHR Respiratory BRU, University of Southampton Faculty of Medicine, Southampton General Hospital, Tremona Road, Southampton, Hampshire SO16 6YD (United Kingdom); Gawalt, Ellen S., E-mail: gawalte@duq.edu [Duquesne University, Department of Chemistry and Biochemistry, McGowan Institute for Regenerative Medicine, 600 Forbes Avenue, Pittsburgh, PA 15282 (United States)

    2013-05-01

    Stainless steel 316L (SS316L) is a common material used in orthopedic implants. Bacterial colonization of the surface and subsequent biofilm development can lead to refractory infection of the implant. Since the greatest risk of infection occurs perioperatively, strategies that reduce bacterial adhesion during this time are important. As a strategy to limit bacterial adhesion and biofilm formation on SS316L, self-assembled monolayers (SAMs) were used to modify the SS316L surface. SAMs with long alkyl chains terminated with hydrophobic (− CH{sub 3}) or hydrophilic (oligoethylene glycol) tail groups were used to form coatings and in an orthogonal approach, SAMs were used to immobilize gentamicin or vancomycin on SS316L for the first time to form an “active” antimicrobial coating to inhibit early biofilm development. Modified SS316L surfaces were characterized using surface infrared spectroscopy, contact angles, MALDI-TOF mass spectrometry and atomic force microscopy. The ability of SAM-modified SS316L to retard biofilm development by Staphylococcus aureus was functionally tested using confocal scanning laser microscopy with COMSTAT image analysis, scanning electron microscopy and colony forming unit analysis. Neither hydrophobic nor hydrophilic SAMs reduced biofilm development. However, gentamicin-linked and vancomycin-linked SAMs significantly reduced S. aureus biofilm formation for up to 24 and 48 h, respectively. - Highlights: ► SS316L was modified with glycol terminated SAMs in order to reduce biofilm growth. ► Antibiotics gentamicin and vancomycin were immobilized on SS316L via SAMs. ► Only the antibiotic modifications reduced biofilm development on SS316L.

  18. Correlation between virulence factors and in vitro biofilm formation by Escherichia coli strains.

    Science.gov (United States)

    Naves, Plínio; del Prado, Gema; Huelves, Lorena; Gracia, Matilde; Ruiz, Vicente; Blanco, Jorge; Dahbi, Ghizlane; Blanco, Miguel; Ponte, María del Carmen; Soriano, Francisco

    2008-08-01

    The ability of 15 Escherichia coli strains to form biofilms on polystirene plates was studied. The strains were serotyped, and their phenotypic expression of surface virulence factors (VFs), and antibiotic susceptibility was also determined. Moreover, 30 VFs-associated genes were analysed, including 15 adhesins (papC, papG and its three alleles, sfa/focDE, sfaS, focG, afa/draBC, iha, bmaE, gafD, nfaE, fimH, fimAvMT78, agn43, F9 fimbriae and type 3 fimbriae-encoding gene clusters), four toxins (hlyA, cnf1, sat and tsh), four siderophore (iron, fyuA, iutA and iucD), five proctetins/invasion-encoding genes (kpsM II, kpsMT III, K1 kps variant- neuC, traT and ibeA), and the pathogenicity island malX and cvaC. Morphological appearance and thickness of biofilms of two strong and three weak biofilm producers were also studied by confocal laser scanning microscopy (CLSM). Seven strains were classified as strong biofilm producers and the remaining eight strains were regarded as weak biofilm producers. Mannose-resistant haemagglutination was the only phenotypically expressed surface virulence factor more frequently found in the strong biofilm group. Five virulence-associated genes were more common (p<0.05) in strong biofilm producers: papC and papG alleles, sfa/focDE, focG, hlyA and cnf1. CLSM images showed irregular biofilms with projections at the top mainly in strong biofilm. PMID:18486439

  19. Characteristics of hydrogen evolution and oxidation catalyzed by Desulfovibrio caledoniensis biofilm on pyrolytic graphite electrode

    International Nuclear Information System (INIS)

    Highlights: → The sulphate-reducing bacteria (SRB) have the ability to catalyze the hydrogen evolution and oxidation on pyrolytic graphite electrode. → The SRB biofilm decreases the overpotential and electron transfer resistance by the CV and EIS detection. → The SRB biofilm can transfer electrons to the 0.24 V polarized pyrolytic graphite electrode and the maximum current is 0.035 mA, which is attributed to SRB catalyzed hydrogen oxidation. → The SRB biofilm also can obtain electron from the -0.61 V polarized PGE to catalyze the hydrogen evolution. - Abstract: Hydrogenase, an important electroactive enzyme of sulphate-reducing bacteria (SRB), has been discovered having the capacity to connect its activity to solid electrodes by catalyzing hydrogen evolution and oxidation. However, little attention has been paid to similar electroactive characteristics of SRB. In this study, the electroactivities of pyrolytic graphite electrode (PGE) coated with SRB biofilm were investigated. Two corresponding redox peaks were observed by cyclic voltammetry detection, which were related to the hydrogen evolution and oxidation. Moreover, the overpotential for the reactions decreased by about 0.2 V in the presence of the SRB biofilm. When the PGE coated with the SRB biofilm was polarized at 0.24 V (vs. SHE), an oxidation current related to the hydrogen oxidation was found. The SRB biofilm was able to obtain electrons from the -0.61 V (vs. SHE) polarized PGE to form hydrogen, and the electron transfer resistance also decreased with the formation of SRB biofilm, as measured by the non-destructive electrochemical impendence spectroscopy detection. It was concluded that the hydrogen evolution and oxidation was an important way for the electron transfer between SRB biofilm and solid electrode in anaerobic environment.

  20. The effect of LED-light action on microbial colony forming ability of several species of staphylococcus

    Science.gov (United States)

    Tuchina, Elena S.; Permyakova, Natalia F.; Tuchin, Valery V.

    2007-05-01

    Photodynamic therapy (PDT) now is widespread for treatment of the various skin infections caused by Propionibacterium acnes or Staphylococcii spp. We used PDT for influence on opportunistic microflora of human skin presented by Staphylococcus hominis, S. warnery, S. epidermidis S. aureus 209 P, S. aureus 69. Species S. epidermidis, S. aureus 209 P, S. hominis to some extent reduced colonies forming ability under action of dual wavelength LED-light (442 nm and 597 nm). For species S. warnery, S. aureus 69 the increase in CFU number under action of light relative to control was characteristic. Our experiments have shown, that phototherapy can be used for treatment of diseases associated with S. aureus 209 P. The doze 8 J/cm2 caused reduction in CFU of this species on 40% relative to control.

  1. Glass-Forming Ability of an Iron-Based Alloy Enhanced by Co Addition and Evaluated by a New Criterion

    Institute of Scientific and Technical Information of China (English)

    CHEN Qing-Jun; SHEN Jun; FAN Hong-Bo; SUN Jian-Fei; HUANG Yong-Jiang; MCCARTNEY D. G.

    2005-01-01

    @@ A new Fe-based alloy that can be cast into a fully amorphous rod with a diameter of at least 16mm by the conventional copper-mould casting technique is obtained by partially replacing Fe with Co in a previously reported Fe-based bulk metallic glass. The preliminary thermodynamic analysis indicates that the Co-containing alloy has a significantly lower Gibbs free energy difference between the undercooled melt and the corresponding crystalline solid, compared to the Co-free alloy, reflecting the dramatic role of the Co addition in stabilizing the supercooled melt and facilitating glass formation in iron-based alloys. Here, a new criterion, derived from the classical nucleation and growth theory, is introduced to evaluate the glass-forming ability of Fe-based bulk metallic glasses.

  2. Synthesis and properties of Cu-Zr-Ag-Al glassy alloys with high glass-forming ability

    International Nuclear Information System (INIS)

    New Cu-Zr-based glassy alloys with an unusual glass-forming ability (GFA) were synthesized in the Cu-Zr-Ag-Al system, based on a ternary Cu45Zr45Ag10 alloy. The quaternary alloys exhibit large supercooled liquid region of 75-108 K and high-reduced glass transition temperature of 0.581-0.610. The best GFA was obtained for Cu36Zr48Ag8Al8 alloy, from which bulk glassy samples of up to 25 mm diameter were successfully fabricated by an injection mold casting method. The bulk glassy alloys exhibit high-compressive fracture strength of 1836-1981 MPa with plastic strain of 0.1-1.0% and excellent corrosion resistance in 1N H2SO4 solution

  3. The effect of Gd addition on the glass-forming ability of Cu-Zr-Al alloy

    Energy Technology Data Exchange (ETDEWEB)

    Fu, H.M. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Faculty of Engineering and Surveying, University of Southern Queensland, Toowoomba QLD 4350 (Australia); Wang, H. [Faculty of Engineering and Surveying, University of Southern Queensland, Toowoomba QLD 4350 (Australia)]. E-mail: wangh@usq.edu.au; Zhang, H.F. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)]. E-mail: hfzhang@imr.ac.cn; Hu, Z.Q. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)

    2006-07-15

    A new Cu-based bulk metallic glass of 10 mm diameter was successfully prepared by a conventional copper mold casting method using alloy Cu{sub 46}Zr{sub 45}Al{sub 7}Gd{sub 2}. The addition of Gd effectively alleviates the harmful effects of oxygen in the melt by the preferential formation of gadolinium oxide and significantly increases the glass-forming ability. The T {sub rg} = T {sub g}/T {sub m} reaches a maximum value of 0.694 for the Cu{sub 46}Zr{sub 45}Al{sub 7}Gd{sub 2} alloy, which is consistent with the experimental results.

  4. Effects of Microalloying on Glass Forming Ability and Thermodynamic Fragility of Cu-Pr-Based Amorphous Alloys

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The effects of microalloying of Ti and B on the glass formation of Cu60Pr30Ni10Al10-2xTixBx(x=0, 0.05%(atom fraction)) amorphous alloys was investigated using differential scanning calorimetry (DSC) and X-ray diffraction (XRD). XRD analysis showed that microalloying with 0.05% Ti and 0.05% B improved the glass forming ability (GFA). The smaller difference in the Gibbs free energy between the liquid and crystalline states at the glass transition temperature (ΔGl-x (Tg)) and the smaller thermodynamic fragility index (ΔSf/Tm, where ΔSf is the entropy of fusion, and Tm is the melting temperature) after microalloying correlated with the higher GFA.

  5. Influence of the Diversity of Bacterial Isolates from Drinking Water on Resistance of Biofilms to Disinfection ▿

    OpenAIRE

    Simões, Lúcia C; Simões, M; Vieira, M. J.

    2010-01-01

    Single- and multispecies biofilms formed by six drinking water-isolated bacterial species were used to assess their susceptibilities to sodium hypochlorite (SHC). In general, multispecies biofilms were more resistant to inactivation and removal than single biofilms. Total biofilm inactivation was achieved only for Acinetobacter calcoaceticus single-species biofilms and for those multispecies biofilms without A. calcoaceticus. Biofilms with all bacteria had the highest resistance t...

  6. Dispersal of human and plant pathogens biofilms via nitric oxide donors at 4 °C.

    Science.gov (United States)

    Marvasi, Massimiliano; Durie, Ian A; Henríquez, Tania; Satkute, Aiste; Matuszewska, Marta; Prado, Raphael Carvalho

    2016-12-01

    Recent studies suggest that nitric oxide donors capable of manipulating nitric oxide-mediated signaling in bacteria could induce dispersal of biofilms. Encased in extracellular polymeric substances, human and plant pathogens within biofilms are significantly more resistant to sanitizers. This is particularly a problem in refrigerated environments where food is processed. In an exercise aimed to study the potential of nitric oxide donors as biofilm dispersal in refrigerated conditions, we compared the ability of different nitric oxide donors (SNAP, NO-aspirin and Noc-5) to dislodge biofilms formed by foodborne, human and plant pathogens treated at 4 °C. The donors SNAP and Noc-5 were efficient in dispersing biofilms formed by Salmonella enterica, pathogenic Escherichia coli and Listeria innocua. The biomasses were decreased up to 30 % when compared with the untreated controls. When the plant pathogens Pectobacterium sp. and Xanthomonas sp. were tested the dispersion was mainly limited to Pectobacterium carotovorum biofilms, decreasing up to 15 % after exposure to molsidomine. Finally, the association of selected nitric oxide donors with sanitizers (DiQuat, H2O2, peracetic acid and PhenoTek II) was effective in dispersing biofilms. The best dispersal was achieved by pre-treating P. carotovorum with molsidomine and then peracetic acid. The synergistic effect was estimated up to ~35 % in dispersal when compared with peracetic acid alone. The association of nitric oxide donors with sanitizers could provide a foundation for an improved sanitization procedure for cleaning refrigerate environments. PMID:27457245

  7. Effects of UV-irradiation on in vitro apatite-forming ability of TiO2 layers

    International Nuclear Information System (INIS)

    Titanium and its alloys are employed as artificial joints, bone plates, wires, screws and bone prostheses in orthopedic and dental fields, because of their high corrosion resistance, good mechanical properties, and biocompatibility. Since they cannot directly bond to living bone-tissue through stable chemical interactions, a few surface modification techniques have been proposed for giving materials apatite-forming ability that secures bone-tissue bonding, such as chemical treatment with H2O2 or NaOH, electrochemical oxidation, electrophoretic apatite particle deposition, and UV-irradiation of surface titanium oxide layer. This study examined how the combination of H2O2 chemical treatment and UV-irradiation affected in vitro apatite-formation on TiO2 (anatase phase) layers as UV was irradiated under a few different conditions. TiO2 layer was prepared by the chemical treatment with H2O2 solution and subsequent heat-treatment (CHT). CHT samples were irradiated with UV-light for 1 h in air or in ultra-pure water. They were then soaked in Kokubo's simulated body fluid (SBF; pH 7.4) at 36.5 deg. C for 1 day. Their surface structure and morphology were examined by using a thin film X-ray diffractometer (TF-XRD), and a scanning electron microscope (SEM). The UV-irradiation of CHT in air reduced the number of active sites for apatite nucleation. On the contrary, however, the UV-irradiation in water increased them. These opposite results indicate that environmental factors of the UV-irradiation are important for controlling the in vitro apatite-forming ability of anatase layer.

  8. Effects of UV-irradiation on in vitro apatite-forming ability of TiO{sub 2} layers

    Energy Technology Data Exchange (ETDEWEB)

    Uetsuki, Keita, E-mail: dns20353@s.okayama-u.ac.jp [Graduate School of Natural Science and Technology, Okayama University, Tsushima, Kita-ku, Okayama-shi 700-8530 (Japan); Nakashima Medical Co., Ltd., Joto-Kitagata, Higashi-ku, Okayama-shi 709-0625 (Japan); Kaneda, Haruki [Faculty of Engineering, Okayama University, Tsushima, Kita-ku, Okayama-shi 700-8530 (Japan); Shirosaki, Yuki [Graduate School of Natural Science and Technology, Okayama University, Tsushima, Kita-ku, Okayama-shi 700-8530 (Japan); Hayakawa, Satoshi [Graduate School of Natural Science and Technology, Okayama University, Tsushima, Kita-ku, Okayama-shi 700-8530 (Japan); Research Center for Biomedical Engineering, Okayama University, Tsushima, Kita-ku, Okayama-shi 700-8530 (Japan); Osaka, Akiyoshi, E-mail: a-osaka@cc.okayama-u.ac.jp [Graduate School of Natural Science and Technology, Okayama University, Tsushima, Kita-ku, Okayama-shi 700-8530 (Japan); Research Center for Biomedical Engineering, Okayama University, Tsushima, Kita-ku, Okayama-shi 700-8530 (Japan)

    2010-10-15

    Titanium and its alloys are employed as artificial joints, bone plates, wires, screws and bone prostheses in orthopedic and dental fields, because of their high corrosion resistance, good mechanical properties, and biocompatibility. Since they cannot directly bond to living bone-tissue through stable chemical interactions, a few surface modification techniques have been proposed for giving materials apatite-forming ability that secures bone-tissue bonding, such as chemical treatment with H{sub 2}O{sub 2} or NaOH, electrochemical oxidation, electrophoretic apatite particle deposition, and UV-irradiation of surface titanium oxide layer. This study examined how the combination of H{sub 2}O{sub 2} chemical treatment and UV-irradiation affected in vitro apatite-formation on TiO{sub 2} (anatase phase) layers as UV was irradiated under a few different conditions. TiO{sub 2} layer was prepared by the chemical treatment with H{sub 2}O{sub 2} solution and subsequent heat-treatment (CHT). CHT samples were irradiated with UV-light for 1 h in air or in ultra-pure water. They were then soaked in Kokubo's simulated body fluid (SBF; pH 7.4) at 36.5 deg. C for 1 day. Their surface structure and morphology were examined by using a thin film X-ray diffractometer (TF-XRD), and a scanning electron microscope (SEM). The UV-irradiation of CHT in air reduced the number of active sites for apatite nucleation. On the contrary, however, the UV-irradiation in water increased them. These opposite results indicate that environmental factors of the UV-irradiation are important for controlling the in vitro apatite-forming ability of anatase layer.

  9. Effect of La addition on glass-forming ability and stability of mechanically alloyed Zr-Ni amorphous alloys

    International Nuclear Information System (INIS)

    Research highlights: → The minor large atom La addition can improve the glass forming ability of Zr-Ni-La and enhance the stability of the amorphous phase against the mechanically induced crystallization. → The stability of the Zr-Ni-La amorphous phase decreases with increasing La content. → The effect of La addition in contrast with the small atomic size C addition plays a significant role in promoting the stability of the amorphous phase. → We try to systematically discuss the reasons of La addition effect on GFA and stability of the amorphous phase from three factor of negative heat of mixing, distance between neighboring atoms and atomic size mismatch, respectively. - Abstract: In this study, the role of La in the microstructural evolution of Zr66.7-xNi33.3Lax (x = 1, 3, 5 at.%) alloys during mechanical alloying has been investigated using X-ray diffraction (XRD), transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The results show that the single amorphous phase of Zr-Ni-La can be obtained through mechanical alloying. The minor La addition can improve the glass forming ability of Zr-Ni-La, enhance the mechanical stability of the amorphous phase against the mechanically induced crystallization and lead to an altered crystallization mode of Zr-Ni alloy. Moreover, the stability of the Zr-Ni-La amorphous phase decreases with further increasing La content. The best effect is obtained for the Zr65.7Ni33.3La1 alloy. Additionally, the effect of La addition in contrast with the small atomic size C addition plays a more significant role in promoting the stability of the amorphous phase. In addition, the reasons of La addition effect on GFA and stability have also been discussed from three factors of negative heat of mixing, distance between neighboring atoms and atomic size mismatch, respectively.

  10. Biofilm diatom community structure: Influence of temporal and substratum variability

    Digital Repository Service at National Institute of Oceanography (India)

    Patil, J.S.; Anil, A.C.

    occasions, the influence of planktonic blooms was also seen on the biofilm community. A comparative study of biofilms formed on the two substrata revealed significant differences in density and diversity. However species composition was almost constant...

  11. Preparation, glass forming ability, crystallization and deformation of (zirconium, hafnium)-copper-nickel-aluminum-titanium-based bulk metallic glasses

    Science.gov (United States)

    Gu, Xiaofeng

    Multicomponent Zr-based bulk metallic glasses are the most promising metallic glass forming systems. They exhibit great glass forming ability and fascinating mechanical properties, and thus are considered as potential structural materials. One potential application is that they could be replacements of the depleted uranium for making kinetic energy armor-piercing projectiles, but the density of existing Zr-based alloys is too low for this application. Based on the chemical and crystallographic similarities between Zr and Hf, we have developed two series of bulk metallic glasses with compositions of (HfxZr1-x) 52.5Cu17.9Ni14.6Al10Ti5 and (HfxZr1-x) 57Cu20Ni8Al10Ti5 ( x = 0--1) by gradually replacing Zr by Hf. Remarkably increased density and improved mechanical properties have been achieved in these alloys. In these glasses, Hf and Zr play an interchangeable role in determining the short range order. Although the glass forming ability decreases continuously with Hf addition, most of these alloys remain bulk glass-forming. Recently, nanocomposites produced from bulk metallic glasses have attracted wide attention due to improved mechanical properties. However, their crystalline microstructure (the grain size and the crystalline volume fraction) has to be optimized. We have investigated crystallization of (Zr, Hf)-based bulk metallic glasses, including the composition dependence of crystallization paths and crystallization mechanisms. Our results indicate that the formation of high number density nanocomposites from bulk metallic glasses can be attributed to easy nucleation and slowing-down growth processes, while the multistage crystallization behavior makes it more convenient to control the microstructure evolution. Metallic glasses are known to exhibit unique plastic deformation behavior. At low temperature and high stress, plastic flow is localized in narrow shear bands. Macroscopic investigations of shear bands (e.g., chemical etching) suggest that the internal

  12. Characteristics, apatite-forming ability and corrosion resistance of NiTi surface modified by AC anodization

    International Nuclear Information System (INIS)

    NiTi samples were anodized in the non-sparking regime using AC voltage in a solution containing calcium and phosphate ions (solution Ca-P). The as-anodized samples were subsequently treated hydrothermally in water (sample A-W-NiTi) or in solution Ca-P (sample A-CaP-NiTi). Thin-film X-ray diffractometry (TF-XRD) analysis confirmed the existence of anatase in the hydrothermally treated samples, but not in the as-anodized sample, while hydroxyapatite (HA) was detected only in sample A-CaP-NiTi. Cross-sectional micrograph by scanning-electron microscopy (SEM) revealed that the thickness of the modified surface layer formed on sample A-CaP-NiTi was ∼200 nm. X-ray photoelectron spectroscopy (XPS) analysis showed that the Ni concentrations at the surface of sample A-W-NiTi and sample A-CaP-NiTi were in the order of 0.4 and 0.3 at.%, respectively, which were about an order of magnitude lower than that for bare NiTi. Both Ca and P were present in the surface layer on as-anodized NiTi and sample A-CaP-NiTi, but negligible on sample A-W-NiTi, as determined from XPS composition depth profiling. Immersion tests in a conventional simulated body fluid (SBF) of the Kokubo type to study apatite-forming ability showed that growth of apatite was induced on A-W-NiTi and much more abundantly on A-CaP-NiTi, but not on bare NiTi and as-anodized NiTi, suggesting that the presence of anatase and HA is favorable for apatite growth. The apatite-forming ability of the samples in the present study may be ranked in ascending order as: bare NiTi < As-anodized NiTi < A-W-NiTi < A-CaP-NiTi. Polarization tests in Hanks' solution recorded significant increase in corrosion resistance due to anodization and further increase was obtained via hydrothermal treatment. The present study thus shows that anodization followed by hydrothermal treatment is a simple method to form a potentially bioactive and at the same time corrosion resistant surface layer on NiTi

  13. There is a specific response to pH by isolates of Haemophilus influenzae and this has a direct influence on biofilm formation

    OpenAIRE

    Ishak, Nadiah; Tikhomirova, Alexandra; Bent, Stephen J.; Ehrlich, Garth D.; Hu, Fen Z; Kidd, Stephen P

    2014-01-01

    Background Haemophilus influenzae colonizes the nasopharynx as a commensal. Strain-specific factors allow some strains to migrate to particular anatomical niches, such as the middle ear, bronchi or blood, and induce disease by surviving within the conditions present at these sites in the body. It is established that H. influenzae colonization and in some cases survival is highly dependent on their ability to form a biofilm. Biofilm formation is a key trait in the development of chronic infect...

  14. Dynamic interactions of neutrophils and biofilms

    Directory of Open Access Journals (Sweden)

    Josefine Hirschfeld

    2014-12-01

    Full Text Available Background: The majority of microbial infections in humans are biofilm-associated and difficult to treat, as biofilms are highly resistant to antimicrobial agents and protect themselves from external threats in various ways. Biofilms are tenaciously attached to surfaces and impede the ability of host defense molecules and cells to penetrate them. On the other hand, some biofilms are beneficial for the host and contain protective microorganisms. Microbes in biofilms express pathogen-associated molecular patterns and epitopes that can be recognized by innate immune cells and opsonins, leading to activation of neutrophils and other leukocytes. Neutrophils are part of the first line of defense and have multiple antimicrobial strategies allowing them to attack pathogenic biofilms. Objective/design: In this paper, interaction modes of neutrophils with biofilms are reviewed. Antimicrobial strategies of neutrophils and the counteractions of the biofilm communities, with special attention to oral biofilms, are presented. Moreover, possible adverse effects of neutrophil activity and their biofilm-promoting side effects are discussed. Results/conclusion: Biofilms are partially, but not entirely, protected against neutrophil assault, which include the processes of phagocytosis, degranulation, and formation of neutrophil extracellular traps. However, virulence factors of microorganisms, microbial composition, and properties of the extracellular matrix determine whether a biofilm and subsequent microbial spread can be controlled by neutrophils and other host defense factors. Besides, neutrophils may inadvertently contribute to the physical and ecological stability of biofilms by promoting selection of more resistant strains. Moreover, neutrophil enzymes can degrade collagen and other proteins and, as a result, cause harm to the host tissues. These parameters could be crucial factors in the onset of periodontal inflammation and the subsequent tissue breakdown.

  15. Biofilm Formation by Hyperpiliated Mutants of Pseudomonas aeruginosa

    OpenAIRE

    Chiang, Poney; Burrows, Lori L.

    2003-01-01

    Under static growth conditions, hyperpiliated, nontwitching pilT and pilU mutants of Pseudomonas aeruginosa formed dense biofilms, showing that adhesion, not twitching motility, is necessary for biofilm initiation. Under flow conditions, the pilT mutant formed mushroom-like structures larger than those of the wild type but the pilU mutant was defective in biofilm formation. Therefore, twitching motility affects the development of biofilm structure, possibly through modulation of detachment.

  16. Current understanding of multi-species biofilms

    DEFF Research Database (Denmark)

    Yang, Liang; Liu, Yang; Wu, Hong;

    2011-01-01

    Direct observation of a wide range of natural microorganisms has revealed the fact that the majority of microbes persist as surface-attached communities surrounded by matrix materials, called biofilms. Biofilms can be formed by a single bacterial strain. However, most natural biofilms are actually...... formed by multiple bacterial species. Conventional methods for bacterial cleaning, such as applications of antibiotics and/or disinfectants are often ineffective for biofilm populations due to their special physiology and physical matrix barrier. It has been estimated that billions of dollars are spent...... every year worldwide to deal with damage to equipment, contaminations of products, energy losses, and infections in human beings resulted from microbial biofilms. Microorganisms compete, cooperate, and communicate with each other in multi-species biofilms. Understanding the mechanisms of multi...

  17. The salmochelin receptor IroN itself, but not salmochelin-mediated iron uptake promotes biofilm formation in extraintestinal pathogenic Escherichia coli (ExPEC).

    Science.gov (United States)

    Magistro, Giuseppe; Hoffmann, Christiane; Schubert, Sören

    2015-01-01

    The key to success of extraintestinal pathogenic Escherichia coli (ExPEC) to colonize niches outside the intestinal tract and to establish infection is the coordinated action of numerous virulence and fitness factors. Intense research revealed not only an arsenal of unique virulence determinants with specific action, but also the multi-functionality of single elements. Especially iron uptake systems of ExPEC proved to be of prime importance. Apart from iron acquisition they optimize certain virulence properties. Here we analyzed the contribution of the salmochelin siderophore system to the ability of ExPEC to form biofilms. In the same iron limited environment, ExPEC displayed a distinct transcriptional profile of siderophore systems. During biofilm formation the iroN gene coding for the specific receptors of the siderophore salmochelin was highly upregulated. Almost no induction was observed during planctonic growth. Disruption of iroN resulted in a reduction of almost 50% in biofilm production. Efficient biofilm formation was not affected in a salmochelin synthesis mutant. Thus, the contribution of IroN is independent from the ability to produce salmochelin. Enhanced expression of IroN did not increase significantly the capacity to form biofilms in ExPEC. Interestingly, the additional expression of IroN or even the acquisition of the entire salmochelin system was not able to improve biofilm formation in a poor biofilm producer like a laboratory E. coli K12 strain. However, complementation with only IroN in an ExPEC iroA deletion mutant was able to restore biofilm formation. The contribution of IroN to biofilm formation appears to require a certain background found in ExPEC, but not in E. coli K12. This study identified the contribution of IroN to biofilm formation and highlights the multi-functional role of iron uptake systems in ExPEC. PMID:25921426

  18. Effect of Ni addition on glass forming ability and thermal stability of Nd-Fe-Al-Ni bulk metallic glasses

    International Nuclear Information System (INIS)

    (Nd60Fe30Al10)100-xNi x (where x = 0, 3, 5, 8 and 10 at%) alloy cylinders with a diameter of 3 mm and a length of 55 mm were prepared by copper mold casting. The effect of Ni addition on glass forming ability (GFA) and thermal stability of Nd-based alloy was investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). It was found that a bulk metallic glass (BMG) composite with a small amount of primary crystallites in the amorphous matrix is formed without Ni addition, and the proportion of crystallites decreases with an increase in the amount of Ni. The (Nd60Fe30Al10)92Ni8 alloy exhibits the best GFA even though there is no apparent glass transition and supercooled liquid region. It is interesting to note that the main melting temperature of the (Nd60Fe30Al10)92Ni8 alloy is lower than its crystallization temperature, resulting in the value of the nominal reduced crystallization temperature T r (=T x/T m) being larger than 1.0. The separation of amorphous phases with different thermal stabilities is believed to be one of the reasons for the anomalous phenomenon. The high GFA of the alloy may be explained in terms of valence concentration and structural stability of the amorphous phase

  19. Efficiency of vanilla, patchouli and ylang ylang essential oils stabilized by iron oxide@C14 nanostructures against bacterial adherence and biofilms formed by Staphylococcus aureus and Klebsiella pneumoniae clinical strains.

    Science.gov (United States)

    Bilcu, Maxim; Grumezescu, Alexandru Mihai; Oprea, Alexandra Elena; Popescu, Roxana Cristina; Mogoșanu, George Dan; Hristu, Radu; Stanciu, George A; Mihailescu, Dan Florin; Lazar, Veronica; Bezirtzoglou, Eugenia; Chifiriuc, Mariana Carmen

    2014-01-01

    Biofilms formed by bacterial cells are associated with drastically enhanced resistance against most antimicrobial agents, contributing to the persistence and chronicization of the microbial infections and to therapy failure. The purpose of this study was to combine the unique properties of magnetic nanoparticles with the antimicrobial activity of three essential oils to obtain novel nanobiosystems that could be used as coatings for catheter pieces with an improved resistance to Staphylococcus aureus and Klebsiella pneumoniae clinical strains adherence and biofilm development. The essential oils of ylang ylang, patchouli and vanilla were stabilized by the interaction with iron oxide@C14 nanoparticles to be further used as coating agents for medical surfaces. Iron oxide@C14 was prepared by co-precipitation of Fe+2 and Fe+3 and myristic acid (C14) in basic medium. Vanilla essential oil loaded nanoparticles pelliculised on the catheter samples surface strongly inhibited both the initial adherence of S. aureus cells (quantified at 24 h) and the development of the mature biofilm quantified at 48 h. Patchouli and ylang-ylang essential oils inhibited mostly the initial adherence phase of S. aureus biofilm development. In the case of K. pneumoniae, all tested nanosystems exhibited similar efficiency, being active mostly against the adherence K. pneumoniae cells to the tested catheter specimens. The new nanobiosystems based on vanilla, patchouli and ylang-ylang essential oils could be of a great interest for the biomedical field, opening new directions for the design of film-coated surfaces with anti-adherence and anti-biofilm properties. PMID:25375335

  20. Efficiency of Vanilla, Patchouli and Ylang Ylang Essential Oils Stabilized by Iron Oxide@C14 Nanostructures against Bacterial Adherence and Biofilms Formed by Staphylococcus aureus and Klebsiella pneumoniae Clinical Strains

    Directory of Open Access Journals (Sweden)

    Maxim Bilcu

    2014-11-01

    Full Text Available Biofilms formed by bacterial cells are associated with drastically enhanced resistance against most antimicrobial agents, contributing to the persistence and chronicization of the microbial infections and to therapy failure. The purpose of this study was to combine the unique properties of magnetic nanoparticles with the antimicrobial activity of three essential oils to obtain novel nanobiosystems that could be used as coatings for catheter pieces with an improved resistance to Staphylococcus aureus and Klebsiella pneumoniae clinical strains adherence and biofilm development. The essential oils of ylang ylang, patchouli and vanilla were stabilized by the interaction with iron oxide@C14 nanoparticles to be further used as coating agents for medical surfaces. Iron oxide@C14 was prepared by co-precipitation of Fe+2 and Fe+3 and myristic acid (C14 in basic medium. Vanilla essential oil loaded nanoparticles pelliculised on the catheter samples surface strongly inhibited both the initial adherence of S. aureus cells (quantified at 24 h and the development of the mature biofilm quantified at 48 h. Patchouli and ylang-ylang essential oils inhibited mostly the initial adherence phase of S. aureus biofilm development. In the case of K. pneumoniae, all tested nanosystems exhibited similar efficiency, being active mostly against the adherence K. pneumoniae cells to the tested catheter specimens. The new nanobiosystems based on vanilla, patchouli and ylang-ylang essential oils could be of a great interest for the biomedical field, opening new directions for the design of film-coated surfaces with anti-adherence and anti-biofilm properties.

  1. The two-component signal transduction system ArlRS regulates Staphylococcus epidermidis biofilm formation in an ica-dependent manner.

    Directory of Open Access Journals (Sweden)

    Yang Wu

    Full Text Available Due to its ability to form biofilms on medical devices, Staphylococcus epidermidis has emerged as a major pathogen of nosocomial infections. In this study, we investigated the role of the two-component signal transduction system ArlRS in regulating S. epidermidis biofilm formation. An ArlRS-deficient mutant, WW06, was constructed using S. epidermidis strain 1457 as a parental strain. Although the growth curve of WW06 was similar to that of SE1457, the mutant strain was unable to form biofilms in vitro. In a rabbit subcutaneous infection model, sterile disks made of polymeric materials were implanted subcutaneously followed with inoculation of WW06 or SE1457. The viable bacteria cells of WW06 recovered from biofilms on the embedded disks were much lower than that of SE1457. Complementation of arlRS genes expression from plasmid in WW06 restored biofilm-forming phenotype both in vivo and in vitro. WW06 maintained the ability to undergo initial attachment. Transcription levels of several genes involved in biofilm formation, including icaADBC, sigB, and sarA, were decreased in WW06, compared to SE1457; and icaR expression was increased in WW06, detected by real-time reverse-transcription PCR. The biofilm-forming phenotype was restored by overexpressing icaADBC in WW06 but not by overexpressing sigB, indicating that ArlRS regulates biofilm formation through the regulation of icaADBC. Gel shift assay showed that ArlR can bind to the promoter region of the ica operon. In conclusion, ArlRS regulates S. epidermidis biofilm formation in an ica-dependent manner, distinct from its role in S. aureus.

  2. Drug resistance mechanisms of fungal biofilms

    OpenAIRE

    Seneviratne, CJ; Samaranayake, LP

    2011-01-01

    Fungi are ubiquitous in nature and exist in soil, water, plants, and in animals and humans. Similar to bacteria, fungi also form confluent biofilms either singly (mono-species) or with other microbial species (mixed-species). Fungal biofilms are known to be highly resistant to the adverse environmental conditions including antimicrobials and biocide compared to its planktonic (free-floating) counterparts. Although bacterial biofilms have been studied in detail, relatively little is known of f...

  3. Enzymatic Detachment of Staphylococcus epidermidis Biofilms

    OpenAIRE

    Kaplan, Jeffrey B.; Ragunath, Chandran; Velliyagounder, Kabilan; Fine, Daniel H.; Ramasubbu, Narayanan

    2004-01-01

    The gram-positive bacterium Staphylococcus epidermidis is the most common cause of infections associated with catheters and other indwelling medical devices. S. epidermidis produces an extracellular slime that enables it to form adherent biofilms on plastic surfaces. We found that a biofilm-releasing enzyme produced by the gram-negative periodontal pathogen Actinobacillus actinomycetemcomitans rapidly and efficiently removed S. epidermidis biofilms from plastic surfaces. The enzyme worked by ...

  4. Biofilm formation is a risk factor for mortality in patients with Candida albicans bloodstream infection-Scotland, 2012-2013.

    Science.gov (United States)

    Rajendran, R; Sherry, L; Nile, C J; Sherriff, A; Johnson, E M; Hanson, M F; Williams, C; Munro, C A; Jones, B J; Ramage, G

    2016-01-01

    Bloodstream infections caused by Candida species remain a significant cause of morbidity and mortality in hospitalized patients. Biofilm formation by Candida species is an important virulence factor for disease pathogenesis. A prospective analysis of patients with Candida bloodstream infection (n = 217) in Scotland (2012-2013) was performed to assess the risk factors associated with patient mortality, in particular the impact of biofilm formation. Candida bloodstream isolates (n = 280) and clinical records for 157 patients were collected through 11 different health boards across Scotland. Biofilm formation by clinical isolates was assessed in vitro with standard biomass assays. The role of biofilm phenotype on treatment efficacy was also evaluated in vitro by treating preformed biofilms with fixed concentrations of different classes of antifungal. Available mortality data for 134 patients showed that the 30-day candidaemia case mortality rate was 41%, with predisposing factors including patient age and catheter removal. Multivariate Cox regression survival analysis for 42 patients showed a significantly higher mortality rate for Candida albicans infection than for Candida glabrata infection. Biofilm-forming ability was significantly associated with C. albicans mortality (34 patients). Finally, in vitro antifungal sensitivity testing showed that low biofilm formers and high biofilm formers were differentially affected by azoles and echinocandins, but not by polyenes. This study provides further evidence that the biofilm phenotype represents a significant clinical entity, and that isolates with this phenotype differentially respond to antifungal therapy in vitro. Collectively, these findings show that greater clinical understanding is required with respect to Candida biofilm infections, and the implications of isolate heterogeneity. PMID:26432192

  5. The marine bacteria Shewanella frigidimarina NCIMB400 upregulates the type VI secretion system during early biofilm formation.

    Science.gov (United States)

    Linares, Denis; Jean, Natacha; Van Overtvelt, Perrine; Ouidir, Tassadit; Hardouin, Julie; Blache, Yves; Molmeret, Maëlle

    2016-02-01

    Shewanella sp. are facultative anaerobic Gram-negative bacteria, extensively studied for their electron transfer ability. Shewanella frigidimarina has been detected and isolated from marine environments, and in particular, from biofilms. However, its ability to adhere to surfaces and form a biofilm is poorly understood. In this study, we show that the ability to adhere and to form a biofilm of S. frigidimarina NCIMB400 is significantly higher than that of Shewanella oneidensis in our conditions. We also show that this strain forms a biofilm in artificial seawater, whereas in Luria-Bertani, this capacity is reduced. To identify proteins involved in early biofilm formation, a proteomic analysis of sessile versus planktonic membrane-enriched fractions allowed the identification of several components of the same type VI secretion system gene cluster: putative Hcp1 and ImpB proteins as well as a forkhead-associated domain-containing protein. The upregulation of Hcp1 a marker of active translocation has been confirmed using quantitative reverse transcription polymerase chain reaction. Our data demonstrated the presence of a single and complete type VI secretion system in S. frigidimarina NCIMB400 genome, upregulated in sessile compared with planktonic conditions. The fact that three proteins including the secreted protein Hcp1 have been identified may suggest that this type VI secretion system is functional. PMID:26617163

  6. Early staphylococcal biofilm formation on solid orthopaedic implant materials: in vitro study.

    Directory of Open Access Journals (Sweden)

    Hironobu Koseki

    Full Text Available Biofilms forming on the surface of biomaterials can cause intractable implant-related infections. Bacterial adherence and early biofilm formation are influenced by the type of biomaterial used and the physical characteristics of implant surface. In this in vitro research, we evaluated the ability of Staphylococcus epidermidis, the main pathogen in implant-related infections, to form biofilms on the surface of the solid orthopaedic biomaterials, oxidized zirconium-niobium alloy, cobalt-chromium-molybdenum alloy (Co-Cr-Mo, titanium alloy (Ti-6Al-4V, commercially pure titanium (cp-Ti and stainless steel. A bacterial suspension of Staphylococcus epidermidis strain RP62A (ATCC35984 was added to the surface of specimens and incubated. The stained biofilms were imaged with a digital optical microscope and the biofilm coverage rate (BCR was calculated. The total amount of biofilm was determined with the crystal violet assay and the number of viable cells in the biofilm was counted using the plate count method. The BCR of all the biomaterials rose in proportion to culture duration. After culturing for 2-4 hours, the BCR was similar for all materials. However, after culturing for 6 hours, the BCR for Co-Cr-Mo alloy was significantly lower than for Ti-6Al-4V, cp-Ti and stainless steel (P0.05. These results suggest that surface properties, such as hydrophobicity or the low surface free energy of Co-Cr-Mo, may have some influence in inhibiting or delaying the two-dimensional expansion of biofilm on surfaces with a similar degree of smoothness.

  7. Career Adapt-Abilities Scale--Italian Form: Psychometric Properties and Relationships to Breadth of Interests, Quality of Life, and Perceived Barriers

    Science.gov (United States)

    Soresi, Salvatore; Nota, Laura; Ferrari, Lea

    2012-01-01

    The Career Adapt-Abilities Scale (CAAS)-Italian Form consists of four 6-item scales, which measure concern, control, curiosity, and confidence as psychosocial resources for managing occupational transitions, developmental tasks, and work traumas. The 24-item CAAS-Italian Form is identical to the International Form 2.0. The factor structure was…

  8. Enhanced Biofilm Formation and Increased Resistance to Antimicrobial Agents and Bacterial Invasion Are Caused by Synergistic Interactions in Multispecies Biofilms

    DEFF Research Database (Denmark)

    Burmølle, Mette; Webb, J.S.; Rao, D.;

    2006-01-01

    Most biofilms in their natural environments are likely to consist of consortia of species that influence each other in synergistic and antagonistic manners. However, few reports specifically address interactions within multispecies biofilms. In this study, 17 epiphytic bacterial strains, isolated...... specific interactions. In summary, our data strongly indicate that synergistic effects promote biofilm biomass and resistance of the biofilm to antimicrobial agents and bacterial invasion in multispecies biofilms.......Most biofilms in their natural environments are likely to consist of consortia of species that influence each other in synergistic and antagonistic manners. However, few reports specifically address interactions within multispecies biofilms. In this study, 17 epiphytic bacterial strains, isolated......-species biofilms resisted invasion to a greater extent than did the biofilms formed by the single species. Replacement of each strain by its cell-free culture supernatant suggested that synergy was dependent both on species-specific physical interactions between cells and on extracellular secreted factors or less...

  9. Impact of Irgarol 1051 on the larval development and metamorphosis of Balanus amphitirite Darwin, diatom, Amphora coffeaformis and natural biofilm

    Digital Repository Service at National Institute of Oceanography (India)

    Desai, D.V.

    The effect of Irgarol 1051 on the biofilm-forming diatom, Amphora coffeaformis, and on natural biofilm was assessed. A reduction in the number of A. coffeaformis cells within a biofilm was observed after treatment with Irgarol 1051, confirming its...

  10. Biofilm formation by Aeromonas hydrophila on green-leafy vegetables: cabbage and lettuce.

    Science.gov (United States)

    Elhariry, Hesham M

    2011-01-01

    Aeromonas hydrophila is the most well known of the six species of Aeromonas, which has been linked to two groups of human diseases: septicemia and gastroenteritis. Reference strain ATCC 7966 and biofilm strains TUB19, TUB20, and TUB21 were investigated for their ability to form biofilm in vitro (after 48 h on polystyrene surface) and on the surface of two green-leafy vegetables, cabbage and lettuce (after 1, 2, 4, and 24 h). Attachment strength (S(R)) of these strains to the vegetable surface was also measured in the same time intervals. The ATCC 7966 and TUB19 had high ability to form biofilm in vitro compared with TUB20 and TUB21 in full strength tryptone soy broth or under starvation conditions in diluted tryptone soy broth (1:20, v/v). Cell surface hydrophobicity of the biofilm strains was lower than that of the reference strain. The biofilm of all tested strains on polystyrene surfaces differed from that on the vegetable surfaces. All strains studied rapidly attached to both green leafy vegetables (after 1 h). S(R) and cell populations (loosely and strongly attached cells) significantly (p 0.05) differences in cell populations were recorded after 4 and 24 h. The highest S(R) and cell population (log CFU cm⁻²) were recorded by TUB19. In conclusion, the use of A. hydrophila strains isolated from environmental biofilm samples may be more useful for understanding biofilm formation on green-leafy vegetables than the reference or laboratory strains. The attachment of A. hydrophila was significantly affected by the surfaces of green-leafy vegetables. Further studies are required to improve our understanding of the interaction between human microbial pathogens and surfaces of raw vegetables. PMID:21034267

  11. Nanotechnology: Role in dental biofilms

    Directory of Open Access Journals (Sweden)

    Bhardwaj Sonia

    2009-01-01

    Full Text Available Biofilms are surface- adherent populations of microorganisms consisting of cells, water and extracellular matrix material Nanotechnology is promising field of science which can guide our understanding of the role of interspecies interaction in the development of biofilm. Streptococcus mutans with other species of bacteria has been known to form dental biofilm. The correlation between genetically modified bacteria Streptococcus mutans and nanoscale morphology has been assessed using AFMi.e atomic force microscopy. Nanotechnology application includes 16 O/ 18 O reverse proteolytic labeling,use of quantum dots for labeling of bacterial cells, selective removal of cariogenic bacteria while preserving the normal oral flora and silver antimicrobial nanotechnology against pathogens associated with biofilms. The future comprises a mouthwash full of smart nanomachines which can allow the harmless flora of mouth to flourish in a healthy ecosystem

  12. Physics of biofilms: the initial stages of biofilm formation and dynamics

    International Nuclear Information System (INIS)

    One of the physiological responses of bacteria to external stress is to assemble into a biofilm. The formation of a biofilm greatly increases a bacterial population's resistance to a hostile environment by shielding cells, for example, from antibiotics. In this paper, we describe the conditions necessary for the emergence of biofilms in natural environments and relate them to the emergence of biofilm formation inside microfluidic devices. We show that competing species of Escherichia coli bacteria form biofilms to spatially segregate themselves in response to starvation stress, and use in situ methods to characterize the physical properties of the biofilms. Finally, we develop a microfluidic platform to study the inter-species interactions and show how biofilm-mediated genetic interactions can improve a species’ resistance to external stress. (paper)

  13. Staphylococcus aureus isolated from handmade sweets: Biofilm formation, enterotoxigenicity and antimicrobial resistance.

    Science.gov (United States)

    Kroning, Isabela Schneid; Iglesias, Mariana Almeida; Sehn, Carla Pohl; Valente Gandra, Tatiane Kuka; Mata, Marcia Magalhães; da Silva, Wladimir Padilha

    2016-09-01

    Staphylococcus aureus is the second most important pathogen involved in foodborne outbreaks in Brazil. Because of their widespread distribution and biofilm forming ability, handmade sweets are easily contaminated with S. aureus. The aim of this study was to isolate and identify coagulase-positive staphylococci (CPS) from handmade sweets produced in Pelotas City/Brazil. The virulence potential was checked by evaluating the presence of the staphylococcal enterotoxin genes, icaA and icaD genes, the biofilm forming potential and antimicrobial resistance of the isolates. It was find just S. aureus among the CPS isolates. All the S. aureus isolates had biofilm forming ability on stainless steel and more than half of them on polystyrene surfaces. The majority of the isolates carried the icaA (66.6%) and icaD (58.4%) genes and some of them had the genes encoding enterotoxins A (33.4%) and B (16.6%). Furthermore, the majority of the isolates (83%) were resistant to at least one of the tested antimicrobials and multidrug resistance was observed in 8.4% of the isolates. The isolates had virulence potential, and half of them were enterotoxigenic. In addition, the ability of all the isolates to produce biofilms highlights the danger posed by these potentially virulent microorganisms persisting in food manufacturing environments. PMID:27217365

  14. Influence of volatile organic compounds emitted by Pseudomonas and Serratia strains on Agrobacterium tumefaciens biofilms.

    Science.gov (United States)

    Plyuta, Vladimir; Lipasova, Valentina; Popova, Alexandra; Koksharova, Olga; Kuznetsov, Alexander; Szegedi, Erno; Chernin, Leonid; Khmel, Inessa

    2016-07-01

    The ability to form biofilms plays an important role in bacteria-host interactions, including plant pathogenicity. In this work, we investigated the action of volatile organic compounds (VOCs) produced by rhizospheric strains of Pseudomonas chlororaphis 449, Pseudomonas fluorescens B-4117, Serratia plymuthica IC1270, as well as Serratia proteamaculans strain 94, isolated from spoiled meat, on biofilms formation by three strains of Agrobacterium tumefaciens which are causative agents of crown-gall disease in a wide range of plants. In dual culture assays, the pool of volatiles emitted by the tested Pseudomonas and Serratia strains suppressed the formation of biofilms of A. tumefaciens strains grown on polycarbonate membrane filters and killed Agrobacterium cells in mature biofilms. The individual VOCs produced by the tested Pseudomonas strains, that is, ketones (2-nonanone, 2-heptanone, 2-undecanone), and dimethyl disulfide (DMDS) produced by Serratia strains, were shown to kill A. tumefaciens cells in mature biofilms and suppress their formation. The data obtained in this study suggest an additional potential of some ketones and DMDS as protectors of plants against A. tumefaciens strains, whose virulence is associated with the formation of biofilms on the infected plants. PMID:27214244

  15. Pock forming ability of fowl pox virus isolated from layer chicken and its adaptation in chicken embryo fibroblast cell culture

    Directory of Open Access Journals (Sweden)

    Varsha Rani Gilhare

    2015-03-01

    Full Text Available Aim: The objective of the present study was to examine pock forming ability of field strain and vaccine strain of fowl pox virus (FPV in chorioallantoic membrane (CAM of embryonated chicken eggs and its adaptation in chicken embryo fibroblast (CEF cell culture. Materials and Methods: Dry scabs were collected from 25 affected birds in glycerin-saline and preserved at 4°C until processed. Virus was isolated in 10-day-old embryonated chicken eggs by dropped CAM method. The identity of the virus is confirmed by clinical findings of affected birds, pock morphology and histopathology of infected CAM. In addition one field isolate and vaccine strain of FPV was adapted to CEF cell culture. CEF cell culture was prepared from 9-day-old embryonated chicken eggs. Result: Clinical symptoms observed in affected birds include pox lesion on comb, wattle, eyelids and legs, no internal lesions were observed. All field isolates produced similar findings in CAM. Pocks produced by field isolates ranged from 3 mm to 5 mm at the third passage while initial passages edematous thickening and necrosis of CAM was observed. Pocks formed by lyophilized strain were ranges from 0.5 mm to 2.5 mm in diameter scattered all over the membrane at the first passage. Intra-cytoplasmic inclusion bodies are found on histopathology of CAM. At third passage level, the CEF inoculated with FPV showed characteristic cytopathic effect (CPE included aggregation of cells, syncytia and plaque formation. Conclusion: FPV field isolates and vaccine strain produced distinct pock lesions on CAMs. Infected CAM showed intracytoplasmic inclusion bodies. The CEF inoculated with FPV field isolate as well as a vaccine strain showed characteristic CPE at third passage level.

  16. In vitro evaluation for apatite-forming ability of cellulose-based nanocomposite scaffolds for bone tissue engineering.

    Science.gov (United States)

    Saber-Samandari, Samaneh; Saber-Samandari, Saeed; Kiyazar, Shiva; Aghazadeh, Jamshid; Sadeghi, Ali

    2016-05-01

    Research on synthetic bioactive bone graft materials has significantly expanded in the past decade. In this study, the nanocomposite scaffold of semi-interpenetrating networks (semi-IPN) cellulose-graft-polyacrylamide/nano-hydroxyapatite was synthesized through free radical polymerization. The scaffolds were fabricated by the freeze-drying technique. The prepared semi-IPN nanocomposite scaffolds were characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD) analysis. In addition, the mechanical properties (i.e., elastic modulus and compressive strength) of the scaffolds were investigated. The SEM images showed that the pores of the scaffolds were interconnected, and their sizes ranged from 120μm to 190μm. Under optimum conditions, the prepared scaffolds had a compressive strength of 4.80MPa, an elastic modulus of 0.29GPa and a value of 47.37% porosity. Furthermore, the apatite-forming ability of the scaffolds was determined using simulated body fluid (SBF) for 28 days. The results revealed that the new apatite particles could grow on the surface of the scaffolds after a 14-day immersion in SBF. Finally, this study suggests that the prepared semi-IPN nanocomposites that closely mimic the properties of bone tissue could be a promising scaffold for bone tissue engineering. PMID:26836617

  17. Effects of Zn addition on the glass forming ability and mechanical properties of Mg–Cu–Gd bulk metallic glasses

    International Nuclear Information System (INIS)

    Highlights: • Mg-Zn-Cu-Gd BMGs with 2 mm diameter are fabricated by copper mold casting method. • The σf and Hv of the Mg60Zn5Cu25Gd10 reach up to 754 MPa and 286 Hv, respectively. • The Mg60Zn5Cu25Gd10 alloy exhibits plastic deformation characteristic at micro-level. -- Abstract: The effects of Zn addition on the glass forming ability (GFA) and mechanical properties are investigated in Mg65−xZnxCu25Gd10 (x = 0, 3, 5, 8 at.%) alloys by X-ray diffractometer (XRD), differential scanning calorimeter (DSC) and mechanical property tests. Thermal analysis shows that with the increasing of Zn content from 0 to 8 at.%, the supercooled liquid regions of Mg65−xZnxCu25Gd10 alloys decrease from 68 K to 31 K, indicating the obvious deterioration in their GFA. On the other hand, however, the mechanical property tests demonstrate that the appropriate addition of Zn (5 at.%) in Mg65−xZnxCu25Gd10 alloys greatly improves the mechanical strength, increases their compressive fracture strength and Vickers hardness from 648 MPa and 257 Hv to 754 MPa and 286 Hv, respectively. In addition, the fracture surface morphologies have been characterized by scanning electron microscopy (SEM) and the dominant fracture behaviors of the as-cast alloys have been explained as well

  18. Role of type 1 and type 3 fimbriae in Klebsiella pneumoniae biofilm formation

    DEFF Research Database (Denmark)

    Schroll, C.; Barken, Kim Bundvig; Krogfelt, K.A.;

    2010-01-01

    nosocomial infections. Most clinical K. pneumoniae isolates express two types of fimbrial adhesins, type 1 fimbriae and type 3 fimbriae. In this study, we characterized the role of type 1 and type 3 fimbriae in K. pneumoniae biofilm formation. Results: Isogenic fimbriae mutants of the clinical K. pneumoniae......Background: Klebsiella pneumoniae is an important gram-negative opportunistic pathogen causing primarily urinary tract infections, respiratory infections, and bacteraemia. The ability of bacteria to form biofilms on medical devices, e. g. catheters, has a major role in development of many...... infections....

  19. Spatial structure, cooperation and competition in biofilms.

    Science.gov (United States)

    Nadell, Carey D; Drescher, Knut; Foster, Kevin R

    2016-09-01

    Bacteria often live within matrix-embedded communities, termed biofilms, which are now understood to be a major mode of microbial life. The study of biofilms has revealed their vast complexity both in terms of resident species composition and phenotypic diversity. Despite this complexity, theoretical and experimental work in the past decade has identified common principles for understanding microbial biofilms. In this Review, we discuss how the spatial arrangement of genotypes within a community influences the cooperative and competitive cell-cell interactions that define biofilm form and function. Furthermore, we argue that a perspective rooted in ecology and evolution is fundamental to progress in microbiology. PMID:27452230

  20. Electroactive biofilms of sulphate reducing bacteria

    International Nuclear Information System (INIS)

    Biofilms formed from a pure strain of Desulfovibrio desulfuricans 27774 on stainless steel and graphite polarised surfaces were studied. The polarisation conditions applied were -0.4 V vs. SCE for different times. A cathodic current related with the biofilms growth was observed with a maximum intensity of -270 mA m-2 that remained stable for several days using graphite electrodes. These sulphate reducing bacteria biofilms present electrocatalytic activity towards hydrogen and oxygen reduction reactions. Electrode polarisation has a selective effect on the catalytic activity. The biofilms were also observed by scanning electronic microscopy revealing the formation of homogeneous films on the surfaces

  1. Biofilm Matrix Proteins

    OpenAIRE

    Fong, Jiunn N. C.; Yildiz, Fitnat H.

    2015-01-01

    Proteinaceous components of the biofilm matrix include secreted extracellular proteins, cell surface adhesins and protein subunits of cell appendages such as flagella and pili. Biofilm matrix proteins play diverse roles in biofilm formation and dissolution. They are involved in attaching cells to surfaces, stabilizing the biofilm matrix via interactions with exopolysaccharide and nucleic acid components, developing three-dimensional biofilm architectures, and dissolving biofilm matrix via enz...

  2. The Assessment of Proteus mirabilis Susceptibility to Ceftazidime and Ciprofloxacin and the Impact of These Antibiotics at Subinhibitory Concentrations on Proteus mirabilis Biofilms

    Directory of Open Access Journals (Sweden)

    Joanna Kwiecińska-Piróg

    2013-01-01

    Full Text Available Rods of the Proteus genus are commonly isolated from patients, especially from the urinary tracts of the catheterised patients. The infections associated with biomaterials are crucial therapeutic obstacles, due to the bactericidal resistance of the biofilm. The aim of this study was to assess the susceptibility of P. mirabilis planktonic forms to ciprofloxacin and ceftazidime, the ability to form biofilm, and the impact of chosen sub-MIC concentrations of these antibiotics on biofilm at different stages of its formation. The research included 50 P. mirabilis strains isolated from wounds and the urinary tracts from patients of the University Hospital No. 1 in Bydgoszcz. The assessment of susceptibility to ciprofloxacin and ceftazidime was conducted using micromethods. The impact of sub-MIC concentrations of the chosen antibiotics on the biofilm was measured using the TTC method. The resistance to ciprofloxacin was confirmed for 20 strains (40.0% while to ceftazidime for 32 (64.0% of the tested P. mirabilis strains. All of the tested strains formed biofilm: 24.0% weakly, 26.0% moderately, and 50.0% strongly. It was determined that ciprofloxacin and ceftazidime caused eradication of the biofilm. Moreover, the connection between origin of the strains, biofilm maturity level, and resistance to antibiotics was proved.

  3. Exploring the diversity of Listeria monocytogenes biofilm architecture by high-throughput confocal laser scanning microscopy and the predominance of the honeycomb-like morphotype.

    Science.gov (United States)

    Guilbaud, Morgan; Piveteau, Pascal; Desvaux, Mickaël; Brisse, Sylvain; Briandet, Romain

    2015-03-01

    Listeria monocytogenes is involved in food-borne illness with a high mortality rate. The persistence of the pathogen along the food chain can be associated with its ability to form biofilms on inert surfaces. While most of the phenotypes associated with biofilms are related to their spatial organization, most published data comparing biofilm formation by L. monocytogenes isolates are based on the quantitative crystal violet assay, which does not give access to structural information. Using a high-throughput confocal-imaging approach, the aim of this work was to decipher the structural diversity of biofilms formed by 96 L. monocytogenes strains isolated from various environments. Prior to large-scale analysis, an experimental design was created to improve L. monocytogenes biofilm formation in microscopic-grade microplates, with special emphasis on the growth medium composition. Microscopic analysis of biofilms formed under the selected conditions by the 96 isolates revealed only weak correlation between the genetic lineages of the isolates and the structural properties of the biofilms. However, a gradient in their geometric descriptors (biovolume, mean thickness, and roughness), ranging from flat multilayers to complex honeycomb-like structures, was shown. The dominant honeycomb-like morphotype was characterized by hollow voids hosting free-swimming cells and localized pockets containing mixtures of dead cells and extracellular DNA (eDNA). PMID:25548046

  4. Aspartate inhibits Staphylococcus aureus biofilm formation.

    Science.gov (United States)

    Yang, Hang; Wang, Mengyue; Yu, Junping; Wei, Hongping

    2015-04-01

    Biofilm formation renders Staphylococcus aureus highly resistant to conventional antibiotics and host defenses. Four D-amino acids (D-Leu, D-Met, D-Trp and D-Tyr) have been reported to be able to inhibit biofilm formation and disassemble established S. aureus biofilms. We report here for the first time that both D- and L-isoforms of aspartate (Asp) inhibited S. aureus biofilm formation on tissue culture plates. Similar biofilm inhibition effects were also observed against other staphylococcal strains, including S. saprophyticus, S. equorum, S. chromogenes and S. haemolyticus. It was found that Asp at high concentrations (>10 mM) inhibited the growth of planktonic N315 cells, but at subinhibitory concentrations decreased the cellular metabolic activity without influencing cell growth. The decreased cellular metabolic activity might be the reason for the production of less protein and DNA in the matrix of the biofilms formed in the presence of Asp. However, varied inhibition efficacies of Asp were observed for biofilms formed by clinical staphylococcal isolates. There might be mechanisms other than decreasing the metabolic activity, e.g. the biofilm phenotypes, affecting biofilm formation in the presence of Asp. PMID:25687923

  5. Focus on the physics of biofilms

    Science.gov (United States)

    Lecuyer, Sigolene; Stocker, Roman; Rusconi, Roberto

    2015-03-01

    Bacteria are the smallest and most abundant form of life. They have traditionally been considered as primarily planktonic organisms, swimming or floating in a liquid medium, and this view has shaped many of the approaches to microbial processes, including for example the design of most antibiotics. However, over the last few decades it has become clear that many bacteria often adopt a sessile, surface-associated lifestyle, forming complex multicellular communities called biofilms. Bacterial biofilms are found in a vast range of environments and have major consequences on human health and industrial processes, from biofouling of surfaces to the spread of diseases. Although the study of biofilms has been biologists’ territory for a long time, a multitude of phenomena in the formation and development of biofilms hinges on physical processes. We are pleased to present a collection of research papers that discuss some of the latest developments in many of the areas to which physicists can contribute a deeper understanding of biofilms, both experimentally and theoretically. The topics covered range from the influence of physical environmental parameters on cell attachment and subsequent biofilm growth, to the use of local probes and imaging techniques to investigate biofilm structure, to the development of biofilms in complex environments and the modeling of colony morphogenesis. The results presented contribute to addressing some of the major challenges in microbiology today, including the prevention of surface contamination, the optimization of biofilm disruption methods and the effectiveness of antibiotic treatments.

  6. Resistance of Candida albicans biofilms to antifungal agents in vitro.

    OpenAIRE

    Hawser, S. P.; Douglas, L J

    1995-01-01

    Biofilms formed by Candida albicans on small discs of catheter material were resistant to the action of five clinically important antifungal agents as determined by [3H]leucine incorporation and tetrazolium reduction assays. Fluconazole showed the greatest activity, and amphotericin B showed the least activity against biofilm cells. These findings were confirmed by scanning electron microscopy of the biofilms.

  7. Role of a Tannerella forsythia exopolysaccharide synthesis operon in biofilm development.

    Science.gov (United States)

    Honma, Kiyonobu; Inagaki, Satoru; Okuda, Katsuji; Kuramitsu, Howard K; Sharma, Ashu

    2007-04-01

    Tannerella forsythia is a Gram-negative oral anaerobe implicated in the development of periodontitis, a chronic inflammatory disease induced by bacterial infections which leads to tooth loss if untreated. Since biofilms formed by periodontal bacteria are considered important in disease progression and pose difficulties in treatment, we sought to investigate the underlying mechanisms of T. forsythia biofilm formation. This was carried out by screening random insertion mutants of T. forsythia for alterations in biofilm development. This approach lead to the identification of an operon involved in exopolysaccharide (EPS) synthesis. An isogenic mutant of one of the genes, wecC, contained within the operon was constructed. The isogenic wecC mutant showed increased ability to form biofilms as compared to the parent strain. The wecC mutant also formed aggregated microcolonies and showed increased cell-surface associated hydrophobicity as compared to the parent strain. Moreover, biochemical characterization of the wecC mutant indicated that glycosylation of surface glycoproteins was reduced. Therefore, our results suggest that the wecC operon is associated with glycosylation of surface-glycoprotein expression and likely plays an inhibitory role in T. forsythia biofilm formation. PMID:17363213

  8. Treatment of Oral Multispecies Biofilms by an Anti-Biofilm Peptide.

    Directory of Open Access Journals (Sweden)

    Zhejun Wang

    Full Text Available Human oral biofilms are multispecies microbial communities that exhibit high resistance to antimicrobial agents. Dental plaque gives rise to highly prevalent and costly biofilm-related oral infections, which lead to caries or other types of oral infections. We investigated the ability of the recently identified anti-biofilm peptide 1018 to induce killing of bacterial cells present within oral multispecies biofilms. At 10 μg/ml (6.5 μM, peptide 1018 was able to significantly (p50% of the biofilm being killed and >35% being dispersed in only 3 minutes. Peptide 1018 may potentially be used by itself or in combination with CHX as a non-toxic and effective anti-biofilm agent for plaque disinfection in clinical dentistry.

  9. Role of biofilm in catheter-associated urinary tract infection

    OpenAIRE

    Trautner, Barbara W.; Darouiche, Rabih O.

    2004-01-01

    The predominant form of life for the majority of microorganisms in any hydrated biologic system is a cooperative community termed a “biofilm.” A biofilm on an indwelling urinary catheter consists of adherent microorganisms, their extracellular products, and host components deposited on the catheter. The biofilm mode of life conveys a survival advantage to the microorganisms associated with it and, thus, biofilm on urinary catheters results in persistent infections that are resistant to antimi...

  10. Penetration of Rifampin through Staphylococcus epidermidis Biofilms

    OpenAIRE

    Zheng, Zhilan; Philip S. Stewart

    2002-01-01

    Rifampin penetrated biofilms formed by Staphylococcus epidermidis but failed to effectively kill the bacteria. Penetration was demonstrated by a simple diffusion cell bioassay and by transmission electron microscopic observation of antibiotic-affected cells at the distal edge of the biofilm.

  11. Biofilm Induced Tolerance Towards Antimicrobial Peptides

    DEFF Research Database (Denmark)

    Folkesson, Anders; Haagensen, Janus Anders Juul; Zampaloni, Claudia;

    2008-01-01

    presence of IncF plasmids expressing altered forms of the transfer pili in two different biofilm model systems. The mature biofilms were subsequently treated with two antibiotics with different molecular targets, the peptide antibiotic colistin and the fluoroquinolone ciprofloxacin. The dynamics of...

  12. Speech and language abilities of children with the familial form of 22q11.2 deletion syndrome

    Directory of Open Access Journals (Sweden)

    Rakonjac Marijana

    2016-01-01

    Full Text Available The 22q11.2 Deletion Syndrome (22q11.2DS, which encompasses Shprintzen syndrome, DiGeorge and velocardiofacial syndrome, is the most common microdeletion syndrome in humans with an estimated incidence of approximately 1/4000 per live births. After Down syndrome, it is the second most common genetic syndrome associated with congenital heart malformations. The mode of inheritance of the 22q11.2DS is autosomal dominant. In approximately 72 - 94% of the cases the deletion has occurred de novo, while in 6 to 28% of patients deletion was inherited from a parent. As a part of a multidisciplinary study we examined the speech and language abilities of members of two families with inherited form of 22q11.2DS. The presence of 22q11.2 microdeletion was revealed by fluorescence in situ hybridization (FISH and/or multiplex ligation-dependent probe amplification (MLPA. In one family we detected 1.5 Mb 22q11.2 microdeletion, while in the other family we found 3Mb microdeletion. Patients from both families showed delays in cognitive, socio-emotional, speech and language development. Furthermore, we found considerable variability in the phenotypic characteristics of 22q11.2DS and the degree of speech-language pathology not only between different families with 22q11.2 deletion, but also among members of the same family. In addition, we detected no correlation between the phenotype and the size of 22q11.2 microdeletion.

  13. Effect of Si addition on glass-forming ability and mechanical properties of Cu-Zr-Al bulk metallic glass

    International Nuclear Information System (INIS)

    Research highlights: The Cu50Zr43Al7 alloy has a surprising GFA, and the glassy rods with diameter of 10 mm have been produced in this research. It has not been reported that the Cu-based glassy rods (Cu ≥ 50 at.%) to be produced with the critical diameter greater than 10 mm. The novelty of this research is that the glass formation has been improved and the critical diameter increased to 12 mm for the alloy having x = 1 with the addition of Si. Different criteria are used to evaluate the influence of Si content on the GFA, and the possible mechanisms involved in the achievement of this GFA are also discussed. - Abstract: The effect of Si addition on the glass-forming ability (GFA) and mechanical properties of (Cu50Zr43Al7)100-xSix (x = 0, 0.5, 1, 1.5 and 2 at.%) alloys were investigated. The GFA of Cu50Zr43Al7 alloy is improved by addition of a small amount of Si, and the critical diameter for glass formation increases from 10 mm for the alloy with x = 0-12 mm for the alloy with x = 1 when prepared using copper mold casting. Different criteria are used to evaluate the influence of Si content on the GFA, and the possible mechanisms involved in the achievement of this GFA are also discussed. In the uniaxial compression, the bulk glassy alloys exhibit a limited plastic strain of less than 1%, but the compressive fracture strength and Young's modulus were obtained in high values of 1969-2129 MPa and 101-144 GPa, respectively. Fracture surface and shear bands of samples were studied by using scanning electron microscopy (SEM).

  14. Effect of Alkali-Acid-Heat Chemical Surface Treatment on Electron Beam Melted Porous Titanium and Its Apatite Forming Ability

    Directory of Open Access Journals (Sweden)

    Suzan Bsat

    2015-04-01

    Full Text Available Advanced additive manufacturing techniques such as electron beam melting (EBM, can produce highly porous structures that resemble the mechanical properties and structure of native bone. However, for orthopaedic applications, such as joint prostheses or bone substitution, the surface must also be bio-functionalized to promote bone growth. In the current work, EBM porous Ti6Al4V alloy was exposed to an alkali acid heat (AlAcH treatment to bio-functionalize the surface of the porous structure. Various molar concentrations (3, 5, 10M and immersion times (6, 24 h of the alkali treatment were used to determine optimal parameters. The apatite forming ability of the samples was evaluated using simulated body fluid (SBF immersion testing. The micro-topography and surface chemistry of AlAcH treated samples were evaluated before and after SBF testing using scanning electron microscopy and energy dispersive X-ray spectroscopy. The AlAcH treatment successfully modified the topographical and chemical characteristics of EBM porous titanium surface creating nano-topographical features ranging from 200–300 nm in size with a titania layer ideal for apatite formation. After 1 and 3 week immersion in SBF, there was no Ca or P present on the surface of as manufactured porous titanium while both elements were present on all AlAcH treated samples except those exposed to 3M, 6 h alkali treatment. An increase in molar concentration and/or immersion time of alkali treatment resulted in an increase in the number of nano-topographical features per unit area as well as the amount of titania on the surface.

  15. Selected mucolytic, anti-inflammatory and cardiovascular drugs change the ability of neutrophils to form extracellular traps (NETs).

    Science.gov (United States)

    Zawrotniak, Marcin; Kozik, Andrzej; Rapala-Kozik, Maria

    2015-01-01

    Neutrophils form the first line of host defense against infections that combat pathogens using two major mechanisms, the phagocytosis or the release of neutrophil extracellular traps (NETs). The netosis (NET formation) exerts additional, unfavorable effects on the fitness of host cells and is also involved at the sites of lung infection, increasing the mucus viscosity and in the circulatory system where it can influence the intravascular clot formation. Although molecular mechanisms underlying the netosis are still incompletely understood, a role of NADPH oxidase that activates the production of reactive oxygen species (ROS) during the initiation of NETs has been well documented. Since several commonly used drugs can affects the netosis, our current study was aimed to determine the effects of selected mucolytic, anti-inflammatory and cardiovascular drugs on NET formation, with a special emphasis on ROS production and NADPH oxidase activity. The treatment of neutrophils with N-acetylcysteine, ketoprofen and ethamsylate reduced the production of ROS by these cells in a dose-dependent manner. NET formation was also modulated by selected drugs. N-acetylcysteine inhibited the netosis but in the presence of H2O2 this neutrophil ability was restored, indicating that N-acetylcysteine may influence the NET formation by modulating ROS productivity. The administration of ethamsylate led to a significant reduction in NET formation and this effect was not restored by H2O2 or S. aureus, suggesting the unexpected additional side effects of this drug. Ketoprofen seemed to promote ROS-independent NET release, simultaneously inhibiting ROS production. The results, obtained in this study strongly suggest that the therapeutic strategies applied in many neutrophil-mediated diseases should take into account the NET-associated effects. PMID:26291043

  16. Fabrication of nanotube arrays on commercially pure titanium and their apatite-forming ability in a simulated body fluid

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, Hsueh-Chuan; Wu, Shih-Ching; Hsu, Shih-Kuang [Department of Dental Technology and Materials Science, Central Taiwan University of Science and Technology, Taiwan, ROC (China); Institute of Biomedical Engineering and Materials Science, Central Taiwan University of Science and Technology, Taiwan, ROC (China); Chang, Yu-Chen [Department of Mechanical and Automation Engineering, Da-Yeh University, Taiwan, ROC (China); Ho, Wen-Fu, E-mail: fujii@nuk.edu.tw [Department of Chemical and Materials Engineering, National University of Kaohsiung, Kaohsiung, Taiwan, ROC (China)

    2015-02-15

    In this study, we investigated self-organized TiO{sub 2} nanotubes that were grown using anodization of commercially pure titanium at 5 V or 10 V in NH{sub 4}F/NaCl electrolyte. The nanotube arrays were annealed at 450 °C for 3 h to convert the amorphous nanotubes to anatase and then they were immersed in simulated body fluid at 37 °C for 0.5, 1, and 14 days. The purpose of this experiment was to evaluate the apatite-formation abilities of anodized Ti nanotubes with different tube diameters and lengths. The nanotubes that formed on the surfaces of Ti were examined using a field emission scanning electron microscope, X-ray diffraction, and X-ray photoelectron spectroscope. When the anodizing potential was increased from 5 V to 10 V, the pore diameter of the nanotube increased from approximately 24–30 nm to 35–53 nm, and the tube length increased from approximately 590 nm to 730 nm. In vitro testing of the heat-treated nanotube arrays indicated that Ca-P formation occurred after only 1 day of immersion in simulated body fluid. This result was particularly apparent in the samples that were anodized at 10 V. It was also found that the thickness of the Ca-P layer increases as the applied potential for anodized c.p. Ti increases. The average thickness of the Ca-P layer on Ti that was anodized at 5 V and 10 V was approximately 170 nm and 190 nm, respectively, after immersion in simulated body fluid for 14 days. - Highlights: • TiO{sub 2} nanotube on Ti surface was formed by anodic oxidation in a NaCl/NH{sub 4}F solution. • TiO{sub 2} layers show a tube length of 590 nm and 730 nm at 5 V and 10 V, respectively. • After soaking in SBF, Ca-P layer completely covered the entire nanotubular surfaces. • The Ca-P layer was thicker on the Ti surface anodized at 10 V.

  17. [Biofilm on a metal surface as a factor of microbial corrosion].

    Science.gov (United States)

    Borets'ka, M O; Kozlova, I P

    2010-01-01

    Main attention was given in the present review to the research methods, phases of biofilm's forming, exopolymer compounds of bacteria as main biofilm forming factor. A microbial corrosion as a result of interaction between the biofilm and metal surface was considered. The interaction was displayed in biomineralization. The future trends of biofilms study were bound with research of their architecture. That architecture was determined by the structure and function of biofilms compounds: biopolymers and biominerals. PMID:20695231

  18. Effect of Educational Agent and Its Form Characteristics on Problem Solving Ability Perception of Students in Online Task Based Learning Media

    Science.gov (United States)

    Akyuz, Halil Ibrahim; Keser, Hafize

    2015-01-01

    The aim of this study is to investigate the effect of an educational agent, used in online task based learning media, and its form characteristics on problem solving ability perceptions of students. 2x2 factorial design is used in this study. The first study factor is the role of the educational agent and the second factor is form characteristics…

  19. Streptococcus gordonii glucosyltransferase promotes biofilm interactions with Candida albicans

    Directory of Open Access Journals (Sweden)

    Austin Ricker

    2014-01-01

    Full Text Available Background: Candida albicans co-aggregates with Streptococcus gordonii to form biofilms and their interactions in mucosal biofilms may lead to pathogenic synergy. Although the functions of glucosyltransferases (Gtf of Mutans streptococci have been well characterized, the biological roles of these enzymes in commensal oral streptococci, such as S. gordonii, in oral biofilm communities are less clear. Objective: The objective of this work was to explore the role of GtfG, the single Gtf enzyme of S. gordonii, in biofilm interactions with C. albicans. Design: Biofilms were grown under salivary flow in flow cells in vitro, or under static conditions in 96 well plates. A panel of isogenic S. gordonii CH1 gtfG mutants and complemented strains were co-inoculated with C. albicans strain SC5314 to form mixed biofilms. Biofilm accretion and binding interactions between the two organisms were tested. Biofilms were quantified using confocal microscopy or the crystal violet assay. Results: The presence of GtfG enhanced dual biofilm accretion, and sucrose supplementation further augmented dual biofilm formation, pointing to a role of newly synthesized glucans. GtfG also promoted binding to C. albicans preformed biofilms. Soluble α-1,6-glucans played a role in these interactions since: 1 a strain producing only soluble glucans (CH107 formed robust dual biofilms under conditions of salivary flow; and 2 the dual biofilm was susceptible to enzymatic breakdown by dextranase which specifically degrades soluble α-1,6-glucans. Conclusion: Our work identified a novel molecular mechanism for C. albicans and S. gordonii biofilm interactions, mediated by GtfG. This protein promotes early biofilm binding of S. gordonii to C. albicans which leads to increased accretion of streptococcal cells in mixed biofilms. We also showed that soluble glucans, with α-1,6-linkages, promoted inter-generic adhesive interactions.

  20. Biofilm Exopolysaccharides of Pathogenic Fungi: Lessons from Bacteria.

    Science.gov (United States)

    Sheppard, Donald C; Howell, P Lynne

    2016-06-10

    Exopolysaccharides play an important structural and functional role in the development and maintenance of microbial biofilms. Although the majority of research to date has focused on the exopolysaccharide systems of biofilm-forming bacteria, recent studies have demonstrated that medically relevant fungi such as Candida albicans and Aspergillus fumigatus also form biofilms during infection. These fungal biofilms share many similarities with those of bacteria, including the presence of secreted exopolysaccharides as core components of the extracellular matrix. This review will highlight our current understanding of fungal biofilm exopolysaccharides, as well as the parallels that can be drawn with those of their bacterial counterparts. PMID:27129222

  1. σ(B) affects biofilm formation under the dual stress conditions imposed by adding salt and low temperature in Listeria monocytogenes.

    Science.gov (United States)

    Lee, Jin-Ju; Lee, Gilho; Shin, Ji-Hyun

    2014-10-01

    The food-borne pathogenic bacteria Listeria monocytogenes can form biofilms on various surfaces including food-processing equipment. Biofilms offer survival benefits to the organisms entrapped against environmental insults. Moreover, the σ(B) transcription factor of L. monocytogenes plays an important role in its survival under various stress conditions. In this study, we evaluated whether σ(B) contributes to biofilm formation when L. monocytogenes is grown under various temperatures and media. When the wild-type strain was grown under static biofilm culture below ambient temperature (15°C) for 72 h, the difference in viable cell number (in both planktonic and biofilm cells) between the wild-type and ΔsigB mutant increased by adding NaCl to BHI broth (9% salt BHI > 6% salt BHI > BHI, w/v), and the specific activity of β-galactosidase was highly induced in the wild-type strain grown in 6% salt containing BHI broth. Furthermore, we measured surface-adhered biofilm forming ability using the crystal violet staining method. The wild-type strain formed a four times larger biofilm than that of the ΔsigB mutant in 6% salt-BHI medium at 15°C over a 72 h incubation and also showed the highest level of β-galactosidase specific activity. However, both the wild-type and ΔsigB mutant L. monocytogenes were defective for forming a biofilm in 9% salt-BHI medium at 15°C. Our results suggest that σ(B) plays an enhanced role in surface-adhered biofilm formation when L. monocytogenes encounters dual stress conditions, such as 6% NaCl and low temperature. PMID:25269605

  2. Gene Transfer Efficiency in Gonococcal Biofilms: Role of Biofilm Age, Architecture, and Pilin Antigenic Variation

    OpenAIRE

    Kouzel, Nadzeya; Oldewurtel, Enno R.; Maier, Berenike

    2015-01-01

    Extracellular DNA is an important structural component of many bacterial biofilms. It is unknown, however, to which extent external DNA is used to transfer genes by means of transformation. Here, we quantified the acquisition of multidrug resistance and visualized its spread under selective and nonselective conditions in biofilms formed by Neisseria gonorrhoeae. The density and architecture of the biofilms were controlled by microstructuring the substratum for bacterial adhesion. Horizontal t...

  3. Combining Biofilm-Controlling Compounds and Antibiotics as a Promising New Way to Control Biofilm Infections

    OpenAIRE

    Andréia Bergamo Estrela; Wolf-Rainer Abraham

    2010-01-01

    Many bacteria grow on surfaces forming biofilms. In this structure, they are well protected and often high dosages of antibiotics cannot clear infectious biofilms. The formation and stabilization of biofilms are mediated by diffusible autoinducers (e.g. N-acyl homoserine lactones, small peptides, furanosyl borate diester). Metabolites interfering with this process have been identified in plants, animals and microbes, and synthetic analogues are known. Additionally, this seems to be not the on...

  4. Detection and Antibiotic Susceptibility Pattern of Biofilm Producing Gram Positive and Gram Negative Bacteria Isolated From a Tertiary Care Hospital of Pakistan

    Directory of Open Access Journals (Sweden)

    Iqbal, M.

    2011-01-01

    Full Text Available Microorganisms adhere to non-living material or living tissue, and form biofilms made up of extracellular polymers/slime. Biofilm-associated microorganisms behave differently from free-floating bacteria with respect to growth rates and ability to resist antimicrobial treatments and therefore pose a public health problem. The objective of this study is to detect the prevalence of biofilm producers among Gram positive and Gram negative bacteria isolated from clinical specimens, and to study their antimicrobial susceptibility pattern. The study was carried out from October 2009 to March 2010, at the Department of Microbiology, Army Medical College/ National University of Sciences and Technology (NUST, Rawalpindi, Pakistan. Clinical specimens were received from various wards of a tertiary care hospital. These were dealt by standard microbiological procedures. Gram positive and Gram negative bacteria isolated were subjected to biofilm detection by congo red agar method (CRA. Antimicrobial susceptibility testing of those isolates, which showed positive results (slime production, was done according to the Kirby-Bauer disc diffusion technique. A total of 150 isolates were tested for the production of biofilm/slime. Among them, 81 isolates showed positive results. From these 81, 51 were Gram positive and 30 were Gram negative. All the 81(54% slime producers showed reduced susceptibility to majority of antibiotics. Bacterial biofilms are an important virulence factor associated with chronic nosocomial infection. Detection of biofilm forming organisms can help in appropriate antibiotic choice.

  5. Poly (Acetyl, Arginyl) Glucosamine as a Biofilm-reducing Water Line Treatment

    Science.gov (United States)

    Bacteria can attach and form biofilms on a surface hindering removal by common disinfectants. Some bacteria are better than others at forming this biofilm but once it is formed many pathogens can reside in the matrix. Salmonella spp. have been shown to have some biofilm forming capabilities but will...

  6. A Look inside the Listeria monocytogenes Biofilms Extracellular Matrix

    Directory of Open Access Journals (Sweden)

    Angelo Colagiorgi

    2016-07-01

    Full Text Available Listeria monocytogenes is a foodborne pathogen able to persist in food industry and is responsible for a severe illness called listeriosis. The ability of L. monocytogenes to persist in environments is due to its capacity to form biofilms that are a sessile community of microorganisms embedded in a self-produced matrix of extracellular polymeric substances (EPS’s. In this review, we summarized recent efforts performed in order to better characterize the polymeric substances that compose the extracellular matrix (ECM of L. monocytogenes biofilms. EPS extraction and analysis led to the identification of polysaccharides, proteins, extracellular DNA, and other molecules within the listerial ECM. All this knowledge will be useful for increasing food protection, suggesting effective strategies for the minimization of persistence of L. monocytogenes in food industry environments.

  7. A putative ABC transporter is involved in negative regulation of biofilm formation by Listeria monocytogenes

    DEFF Research Database (Denmark)

    Zhu, Xinna; Long, Fei; Chen, Yonghui;

    2008-01-01

    Listeria monocytogenes may persist for long periods in food processing environments. In some instances, this may be due to aggregation or biofilm formation. To investigate the mechanism controlling biofilm formation in the food-borne pathogen L. monocytogenes, we characterized LM-49, a mutant with...... enhanced ability of biofilm-formation generated via transposon Tn917 mutagenesis of L. monocytogenes 4b G. In this mutant, a Tn917 insertion has disrupted the coding region of the gene encoding a putative ATP binding cassette (ABC) transporter permease identical to Lmof2365_1771 (a putative ABC......-transporter permease) presented in the sequenced strain L. monocytogenes str. 4b F2365. This disrupted gene, denoted lm.G_1771, encoded a protein with 10 transmembrane helixes. The revertant, LM-49RE, was obtained by replacing lm.G_1771::Tn917 with lm.G_1771 via homologous recombination. We found that LM-49RE formed...

  8. Influence of glyphosate in planktonic and biofilm growth of Pseudomonas aeruginosa

    Directory of Open Access Journals (Sweden)

    Ilana Schneider Lima

    2014-09-01

    Full Text Available This study evaluated the impact of different concentrations of glyphosate (Rondup® on planktonic and biofilm growth of P. aeruginosa. Aerobic and anaerobic cultures of P. aeruginosa ATCC®15442 inoculated in MHB + glyphosate (0.845 ppm, 1.690 ppm, 8.45 ppm, 16.90 ppm, 84.50 ppm, 169 ppm, 845 ppm, and 1690 ppm and cultured in normoxia and anoxia, following their OD560nm every hour for 24 h. Biofilms of adapted cells were formed in the presence of glyphosate (0.845 to 1690 ppm in normoxia and anoxia for 36 h. Glyphosate at concentrations higher than 84.5 ppm reduces the cell density of planktonic aerobic cultures (p 0.05, and more pronounced over 169 ppm. Anaerobic biofilms have their growth more readily favored (p < 0.05, regardless of concentration. In a concentration-dependent manner, glyphosate interferes with the growth ability of P. aeruginosa ATCC®15442.

  9. Relationship between Antibiotic Resistance, Biofilm Formation, and Biofilm-Specific Resistance in Acinetobacter baumannii.

    Science.gov (United States)

    Qi, Lihua; Li, Hao; Zhang, Chuanfu; Liang, Beibei; Li, Jie; Wang, Ligui; Du, Xinying; Liu, Xuelin; Qiu, Shaofu; Song, Hongbin

    2016-01-01

    In this study, we aimed to examine the relationships between antibiotic resistance, biofilm formation, and biofilm-specific resistance in clinical isolates of Acinetobacter baumannii. The tested 272 isolates were collected from several hospitals in China during 2010-2013. Biofilm-forming capacities were evaluated using the crystal violet staining method. Antibiotic resistance/susceptibility profiles to 21 antibiotics were assessed using VITEK 2 system, broth microdilution method or the Kirby-Bauer disc diffusion method. The minimum inhibitory concentration (MIC) and minimum biofilm eradication concentration (MBEC) to cefotaxime, imipenem, and ciprofloxacin were evaluated using micro dilution assays. Genetic relatedness of the isolates was also analyzed by pulsed-field gel electrophoresis (PFGE) and plasmid profile. Among all the 272 isolates, 31 were multidrug-resistant (MDR), and 166 were extensively drug-resistant (XDR). PFGE typing revealed 167 pattern types and 103 clusters with a similarity of 80%. MDR and XDR isolates built up the main prevalent genotypes. Most of the non-MDR isolates were distributed in a scattered pattern. Additionally, 249 isolates exhibited biofilm formation, among which 63 were stronger biofilm formers than type strain ATCC19606. Population that exhibited more robust biofilm formation likely contained larger proportion of non-MDR isolates. Isolates with higher level of resistance tended to form weaker biofilms. The MBECs for cefotaxime, imipenem, and ciprofloxacin showed a positive correlation with corresponding MICs, while the enhancement in resistance occurred independent of the quantity of biofilm biomass produced. Results from this study imply that biofilm acts as a mechanism for bacteria to get a better survival, especially in isolates with resistance level not high enough. Moreover, even though biofilms formed by isolates with high level of resistance are always weak, they could still provide similar level of protection for the

  10. Effects of Cu substitution for Fe on the glass-forming ability and soft magnetic properties for Fe-based bulk metallic glasses

    International Nuclear Information System (INIS)

    The effects of Cu substitution for Fe on the glass-forming ability (GFA) and soft magnetic properties for Fe72−xCuxB20Si4Nb4 (x=0.0, 0.2, 0.4, 0.6, 0.8, and 1.0) bulk metallic glasses (BMGs) are investigated. It is found that the investigated BMGs exhibit large GFA as well as excellent soft magnetic properties, and proper substitution of Fe by Cu improves the saturation magnetization, coercive force, and effective permeability without obvious deterioration of the GFA. - Highlights: • Fully glassy rods of Fe72−xCuxB20Si4Nb4 BMGs were produced above 1 mm in diameter. • Investigated BMGs exhibit large glass-forming ability and excellent soft magnetic properties. • Proper Cu substitution improves magnetic properties without obvious deterioration of glass-forming ability

  11. Introduction to Biofilms Thematic Minireview Series.

    Science.gov (United States)

    Allewell, Norma M

    2016-06-10

    The biofilms that many bacteria and fungi produce enable them to form communities, adhere tightly to surfaces, evade host immunity, and resist antibiotics. Pathogenic microorganisms that form biofilms are very difficult to eradicate and thus are a frequent source of life-threatening, hospital-acquired infections. This series of five minireviews from the Journal of Biological Chemistry provides a broad overview of our current understanding of biofilms and the challenges that remain. The structure, biosynthesis, and biological function of the biofilms produced by pathogenic fungi are the subject of the first article, by Sheppard and Howell. Gunn, Bakaletz, and Wozniak focus on the biochemistry and structure of bacterial biofilms, how these structures enable bacteria to evade host immunity, and current and developing strategies for overcoming this resistance. The third and fourth articles present two of the best understood cell signaling pathways involved in biofilm formation. Valentini and Filloux focus on cyclic di-GMP, while Kavanaugh and Horswill discuss the quorum-sensing (agr) system and the relationship between quorum sensing and biofilm formation. Mechanisms of antibiotic resistance, particularly the role of efflux pumps and the development of persister cells, are the topics of the final article by Van Acker and Coenye. The advances described in this series guarantee that ongoing interdisciplinary and international efforts will lead to new insights into the basic biology of biofilm formation, as well as new strategies for therapeutic interventions. PMID:27129220

  12. Osteopontin reduces biofilm formation in a multi-species model of dental biofilm.

    Directory of Open Access Journals (Sweden)

    Sebastian Schlafer

    Full Text Available BACKGROUND: Combating dental biofilm formation is the most effective means for the prevention of caries, one of the most widespread human diseases. Among the chemical supplements to mechanical tooth cleaning procedures, non-bactericidal adjuncts that target the mechanisms of bacterial biofilm formation have gained increasing interest in recent years. Milk proteins, such as lactoferrin, have been shown to interfere with bacterial colonization of saliva-coated surfaces. We here study the effect of bovine milk osteopontin (OPN, a highly phosphorylated whey glycoprotein, on a multispecies in vitro model of dental biofilm. While considerable research effort focuses on the interaction of OPN with mammalian cells, there are no data investigating the influence of OPN on bacterial biofilms. METHODOLOGY/PRINCIPAL FINDINGS: Biofilms consisting of Streptococcus oralis, Actinomyces naeslundii, Streptococcus mitis, Streptococcus downei and Streptococcus sanguinis were grown in a flow cell system that permitted in situ microscopic analysis. Crystal violet staining showed significantly less biofilm formation in the presence of OPN, as compared to biofilms grown without OPN or biofilms grown in the presence of caseinoglycomacropeptide, another phosphorylated milk protein. Confocal microscopy revealed that OPN bound to the surface of bacterial cells and reduced mechanical stability of the biofilms without affecting cell viability. The bacterial composition of the biofilms, determined by fluorescence in situ hybridization, changed considerably in the presence of OPN. In particular, colonization of S. mitis, the best biofilm former in the model, was reduced dramatically. CONCLUSIONS/SIGNIFICANCE: OPN strongly reduces the amount of biofilm formed in a well-defined laboratory model of acidogenic dental biofilm. If a similar effect can be observed in vivo, OPN might serve as a valuable adjunct to mechanical tooth cleaning procedures.

  13. Biophysics of biofilm infection.

    Science.gov (United States)

    Stewart, Philip S

    2014-04-01

    This article examines a likely basis of the tenacity of biofilm infections that has received relatively little attention: the resistance of biofilms to mechanical clearance. One way that a biofilm infection persists is by withstanding the flow of fluid or other mechanical forces that work to wash or sweep microorganisms out of the body. The fundamental criterion for mechanical persistence is that the biofilm failure strength exceeds the external applied stress. Mechanical failure of the biofilm and release of planktonic microbial cells is also important in vivo because it can result in dissemination of infection. The fundamental criterion for detachment and dissemination is that the applied stress exceeds the biofilm failure strength. The apparent contradiction for a biofilm to both persist and disseminate is resolved by recognizing that biofilm material properties are inherently heterogeneous. There are also mechanical aspects to the ways that infectious biofilms evade leukocyte phagocytosis. The possibility of alternative therapies for treating biofilm infections that work by reducing biofilm cohesion could (1) allow prevailing hydrodynamic shear to remove biofilm, (2) increase the efficacy of designed interventions for removing biofilms, (3) enable phagocytic engulfment of softened biofilm aggregates, and (4) improve phagocyte mobility and access to biofilm. PMID:24376149

  14. A genomic region involved in the formation of adhesin fibers in Bacillus cereus biofilms

    Directory of Open Access Journals (Sweden)

    Joaquín eCaro-Astorga

    2015-01-01

    Full Text Available Bacillus cereus is a bacterial pathogen that is responsible for many recurrent disease outbreaks due to food contamination. Spores and biofilms are considered the most important reservoirs of B. cereus in contaminated fresh vegetables and fruits. Biofilms are bacterial communities that are difficult to eradicate from biotic and abiotic surfaces because of their stable and extremely strong extracellular matrix. These extracellular matrixes contain exopolysaccharides, proteins, extracellular DNA, and other minor components. Although B. cereus can form biofilms, the bacterial features governing assembly of the protective extracellular matrix are not known. Using the well-studied bacterium B. subtilis as a model, we identified two genomic loci in B. cereus, which encodes two orthologs of the amyloid-like protein TasA of B. subtilis and a SipW signal peptidase. Deletion of this genomic region in B. cereus inhibited biofilm assembly; notably, mutation of the putative signal peptidase SipW caused the same phenotype. However, mutations in tasA or calY did not completely prevent biofilm formation; strains that were mutated for either of these genes formed phenotypically different surface attached biofilms. Electron microscopy studies revealed that TasA polymerizes to form long and abundant fibers on cell surfaces, whereas CalY does not aggregate similarly. Heterologous expression of this amyloid-like cassette in a B. subtilis strain lacking the factors required for the assembly of TasA amyloid-like fibers revealed i the involvement of this B. cereus genomic region in formation of the air-liquid interphase pellicles and ii the intrinsic ability of TasA to form fibers similar to the amyloid-like fibers produced by its B. subtilis ortholog.

  15. Genetic Basis for Saccharomyces cerevisiae Biofilm in Liquid Medium

    DEFF Research Database (Denmark)

    Andersen, Kaj Scherz; Bojsen, Rasmus Kenneth; Gro Rejkjær Sørensen, Laura; Weiss Nielsen, Martin; Lisby, Michael; Folkesson, Sven Anders; Regenberg, Birgitte

    2014-01-01

    Biofilm-forming microorganisms switch between two forms: free-living planktonic and sessile multicellular. Sessile communities of yeast biofilms in liquid medium provide a primitive example of multicellularity and are clinically important because biofilms tend to have other growth characteristics...... than free-living cells. We investigated the genetic basis for yeast, Saccharomyces cerevisiae, biofilm on solid surfaces in liquid medium by screening a comprehensive deletion mutant collection in the S1278b background and found 71 genes that were essential for biofilm development. Quantitative...... functioned specifically in biofilm and mat formation. In a tpk3 mutant, transcription of FLO11 was induced three-fold compared with wild-type, but biofilm development and cell–cell adhesion was absent, suggesting that Tpk3p regulates FLO11 positive posttranscriptionally and negative transcriptionally. The...

  16. Diversity and functions of bacterial community in drinking water biofilms revealed by high-throughput sequencing

    OpenAIRE

    Chao, Yuanqing; Mao, Yanping; Wang, Zhiping,; Tong ZHANG

    2015-01-01

    The development of biofilms in drinking water (DW) systems may cause various problems to water quality. To investigate the community structure of biofilms on different pipe materials and the global/specific metabolic functions of DW biofilms, PCR-based 454 pyrosequencing data for 16S rRNA genes and Illumina metagenomic data were generated and analysed. Considerable differences in bacterial diversity and taxonomic structure were identified between biofilms formed on stainless steel and biofilm...

  17. Roles of RPS41 in Biofilm Formation, Virulence, and Hydrogen Peroxide Sensitivity in Candida albicans.

    Science.gov (United States)

    Lu, Hui; Xiong, Juan; Shang, Qinghua; Jiang, Yuanying; Cao, Yingying

    2016-06-01

    In eukaryotes, loss of cytoplasmic ribosomal proteins (RPs) results in a reduced growth rate and other phenotypic defects. The ability to transition from a unicellular budding yeast to a filamentous form is very important for biofilm formation and virulence in Candida albicans. Our recent study found that loss of the RPS41 (C2_10620W_A) gene but not its paralog RPS42 (C1_01640W_A) resulted in altered growth and filamentation changes in C. albicans, so we hypothesized that the RPS41 gene should play important roles in virulence and biofilm formation in this pathogen. We found that both virulence and the ability to form biofilms were defective due to deletion of the RPS41 gene. We also found that loss of the RPS41 gene increased sensitivity to hydrogen peroxide, and that hydrogen peroxide induced the expression of the RPS41 gene in a wild-type strain. These results suggested that the RPS41 gene plays important roles in C. albicans biofilm formation, virulence, and susceptibility to hydrogen peroxide. PMID:26952720

  18. 2-Aminopyrimidine as a novel scaffold for biofilm modulation.

    Science.gov (United States)

    Lindsey, Erick A; Worthington, Roberta J; Alcaraz, Cristina; Melander, Christian

    2012-04-01

    An efficient synthetic route to a series of substituted 2-aminopyrimidine (2-AP) derivatives has been developed. Subsequent biofilm screening has allowed comparison between the biological activity of these new derivatives and that of the 2-aminoimidazole class of anti-biofilm compounds. Several derivatives displayed the ability to modulate bacterial biofilm formation, exhibiting greater activity against Gram-positive strains than Gram-negative strains. Additionally some 2-aminopyrmidines were able to suppress MRSA resistance to conventional antibiotics. PMID:22301774

  19. 2-Aminopyrimidine as a Novel Scaffold for Biofilm Modulation

    OpenAIRE

    Lindsey, Erick A; Worthington, Roberta J.; Alcaraz, Cristina; Melander, Christian

    2012-01-01

    An efficient synthetic route to a series of substituted 2-aminopyrimidine (2-AP) derivatives has been developed. Subsequent biofilm screening has allowed comparison between the biological activity of these new derivatives and that of the 2-aminoimidazole class of anti-biofilm compounds. Several derivatives displayed the ability to modulate bacterial biofilm formation, exhibiting greater activity against Gram-positive strains than Gram-negative strains. Additionally some 2-aminopyrmidines were...

  20. Hydrodynamic dispersion within porous biofilms.

    Science.gov (United States)

    Davit, Y; Byrne, H; Osborne, J; Pitt-Francis, J; Gavaghan, D; Quintard, M

    2013-01-01

    Many microorganisms live within surface-associated consortia, termed biofilms, that can form intricate porous structures interspersed with a network of fluid channels. In such systems, transport phenomena, including flow and advection, regulate various aspects of cell behavior by controlling nutrient supply, evacuation of waste products, and permeation of antimicrobial agents. This study presents multiscale analysis of solute transport in these porous biofilms. We start our analysis with a channel-scale description of mass transport and use the method of volume averaging to derive a set of homogenized equations at the biofilm-scale in the case where the width of the channels is significantly smaller than the thickness of the biofilm. We show that solute transport may be described via two coupled partial differential equations or telegrapher's equations for the averaged concentrations. These models are particularly relevant for chemicals, such as some antimicrobial agents, that penetrate cell clusters very slowly. In most cases, especially for nutrients, solute penetration is faster, and transport can be described via an advection-dispersion equation. In this simpler case, the effective diffusion is characterized by a second-order tensor whose components depend on (1) the topology of the channels' network; (2) the solute's diffusion coefficients in the fluid and the cell clusters; (3) hydrodynamic dispersion effects; and (4) an additional dispersion term intrinsic to the two-phase configuration. Although solute transport in biofilms is commonly thought to be diffusion dominated, this analysis shows that hydrodynamic dispersion effects may significantly contribute to transport. PMID:23410370

  1. Differential growth of wrinkled biofilms

    Science.gov (United States)

    Espeso, D. R.; Carpio, A.; Einarsson, B.

    2015-02-01

    Biofilms are antibiotic-resistant bacterial aggregates that grow on moist surfaces and can trigger hospital-acquired infections. They provide a classical example in biology where the dynamics of cellular communities may be observed and studied. Gene expression regulates cell division and differentiation, which affect the biofilm architecture. Mechanical and chemical processes shape the resulting structure. We gain insight into the interplay between cellular and mechanical processes during biofilm development on air-agar interfaces by means of a hybrid model. Cellular behavior is governed by stochastic rules informed by a cascade of concentration fields for nutrients, waste, and autoinducers. Cellular differentiation and death alter the structure and the mechanical properties of the biofilm, which is deformed according to Föppl-Von Kármán equations informed by cellular processes and the interaction with the substratum. Stiffness gradients due to growth and swelling produce wrinkle branching. We are able to reproduce wrinkled structures often formed by biofilms on air-agar interfaces, as well as spatial distributions of differentiated cells commonly observed with B. subtilis.

  2. Biofilms of Enterococcus faecalis and Enterococcus faecium isolated from the processing of ricotta and the control of these pathogens through cleaning and sanitization procedures.

    Science.gov (United States)

    da Silva Fernandes, Meg; Kabuki, Dirce Yorika; Kuaye, Arnaldo Yoshiteru

    2015-05-01

    The biofilm formation of Enterococcus faecalis and Enterococcus faecium isolated from the processing of ricotta on stainless steel coupons was evaluated, and the effect of cleaning and sanitization procedures in the control of these biofilms was determined. The formation of biofilms was observed while varying the incubation temperature (7, 25 and 39°C) and time (0, 1, 2, 4, 6 and 8 days). At 7°C, the counts of E. faecalis and E. faecium were below 2 log10 CFU/cm(2). For the temperatures of 25 and 39°C, after 1 day, the counts of E. faecalis and E. faecium were 5.75 and 6.07 log10 CFU/cm(2), respectively, which is characteristic of biofilm formation. The tested sanitation procedures a) acid-anionic tensioactive cleaning, b) anionic tensioactive cleaning+sanitizer and c) acid-anionic tensioactive cleaning+sanitizer were effective in removing the biofilms, reducing the counts to levels below 0.4 log10 CFU/cm(2). The sanitizer biguanide was the least effective, and peracetic acid was the most effective. These studies revealed the ability of enterococci to form biofilms and the importance of the cleaning step and the type of sanitizer used in sanitation processes for the effective removal of biofilms. PMID:25702883

  3. Comparison of UVB and UVC irradiation disinfection efficacies on Pseudomonas Aeruginosa (P. aeruginosa) biofilm

    Science.gov (United States)

    Argyraki, A.; Markvart, M.; Nielsen, Anne; Bjarnsholt, T.; Bjørndal, L.; Petersen, P. M.

    2016-04-01

    Disinfection routines are important in all clinical applications. The uprising problem of antibiotic resistance has driven major research efforts towards alternative disinfection approaches, involving light-based solutions. Pseudomonas aeruginosa (P. aeruginosa) is a common bacterium that can cause skin, soft tissue, lungs, kidney and urinary tract infections. Moreover, it can be found on and in medical equipment causing often cross infections in hospitals. The objective of this study was to test the efficiency, of two different light-based disinfection treatments, namely UVB and UVC irradiation, on P. aeruginosa biofilms at different growth stages. In our experiments a new type of UV light emitting diodes (LEDs) were used to deliver UV irradiation on the biofilms, in the UVB (296nm) and UVC (266nm) region. The killing rate was studied as a function of dose for 24h grown biofilms. The dose was ramped from 72J/m2 to 10000J/m2. It was shown that UVB irradiation was more effective than UVC irradiation in inactivating P. aeruginosa biofilms. No colony forming units (CFU) were observed for the UVB treated biofilms when the dose was 10000 J/m2 (CFU in control sample: 7.5 x 104). UVB irradiation at a dose of 20000J/m2 on mature biofilms (72h grown) resulted in a 3.9 log killing efficacy. The fact that the wavelength of 296nm exists in daylight and has such disinfection ability on biofilms gives new perspectives for applications within disinfection at hospitals.

  4. Inactivation of Gram-positive biofilms by low-temperature plasma jet at atmospheric pressure

    Science.gov (United States)

    Marchal, F.; Robert, H.; Merbahi, N.; Fontagné-Faucher, C.; Yousfi, M.; Romain, C. E.; Eichwald, O.; Rondel, C.; Gabriel, B.

    2012-08-01

    This work is devoted to the evaluation of the efficiency of a new low-temperature plasma jet driven in ambient air by a dc-corona discharge to inactivate adherent cells and biofilms of Gram-positive bacteria. The selected microorganisms were lactic acid bacteria, a Weissella confusa strain which has the particularity to excrete a polysaccharide polymer (dextran) when sucrose is present. Both adherent cells and biofilms were treated with the low-temperature plasma jet for different exposure times. The antimicrobial efficiency of the plasma was tested against adherent cells and 48 h-old biofilms grown with or without sucrose. Bacterial survival was estimated using both colony-forming unit counts and fluorescence-based assays for bacterial cell viability. The experiments show the ability of the low-temperature plasma jet at atmospheric pressure to inactivate the bacteria. An increased resistance of bacteria embedded within biofilms is clearly observed. The resistance is also significantly higher with biofilm in the presence of sucrose, which indicates that dextran could play a protective role.

  5. Biofilm formation by Streptococcus agalactiae: influence of environmental conditions and implicated virulence factors

    Directory of Open Access Journals (Sweden)

    Imma eMargarit

    2015-02-01

    Full Text Available Streptococcus agalactiae (Group B Streptococcus, GBS is an important human pathogen that colonizes the urogenital and/or the lower gastro-intestinal tract of up to 40% of healthy women of reproductive age and is a leading cause of sepsis and meningitis in the neonates. GBS can also infect the elderly and immuno-compromised adults, and is responsible for mastitis in bovines. Like other Gram-positive bacteria, GBS can form biofilm-like three-dimensional structures that could enhance its ability to colonize and persist in the host. Biofilm formation by GBS has been investigated in vitro and appears tightly controlled by environmental conditions. Several adhesins have been shown to play a role in the formation of GBS biofilm-like structures, among which are the protein components of pili protruding outside the bacterial surface. Remarkably, antibodies directed against pilus proteins can prevent the formation of biofilms. The implications of biofilm formation in the context of GBS asymptomatic colonization and dissemination to cause invasive disease remain to be investigated in detail.

  6. Effects of nutritional and environmental conditions on Sinorhizobium meliloti biofilm formation.

    Science.gov (United States)

    Rinaudi, Luciana; Fujishige, Nancy A; Hirsch, Ann M; Banchio, Erika; Zorreguieta, Angeles; Giordano, Walter

    2006-11-01

    Rhizobia are non-spore-forming soil bacteria that fix atmospheric nitrogen into ammonia in a symbiosis with legume roots. However, in the absence of a legume host, rhizobia manage to survive and hence must have evolved strategies to adapt to diverse environmental conditions. The capacity to respond to variations in nutrient availability enables the persistence of rhizobial species in soil, and consequently improves their ability to colonize and to survive in the host plant. Rhizobia, like many other soil bacteria, persist in nature most likely in sessile communities known as biofilms, which are most often composed of multiple microbial species. We have been employing in vitro assays to study environmental parameters that might influence biofilm formation in the Medicago symbiont Sinorhizobium meliloti. These parameters include carbon source, amount of nitrate, phosphate, calcium and magnesium as well as the effects of osmolarity and pH. The microtiter plate assay facilitates the detection of subtle differences in rhizobial biofilms in response to these parameters, thereby providing insight into how environmental stress or nutritional status influences rhizobial survival. Nutrients such as sucrose, phosphate and calcium enhance biofilm formation as their concentrations increase, whereas extreme temperatures and pH negatively affect biofilm formation. PMID:16887339

  7. Coexistence and survival of pathogenic leptospires by formation of biofilm with Azospirillum.

    Science.gov (United States)

    Kumar, K Vinod; Lall, Chandan; Raj, R Vimal; Vedhagiri, K; Vijayachari, P

    2015-06-01

    Pathogenic Leptospira spp. represent one cause of leptospirosis worldwide and have long been regarded as solitary organisms in soil and aquatic environments. However, in the present study, Leptospira interrogans was observed to be associated with environmental biofilms with 21 bacterial isolates belonging to 10 genera. All 21 isolates were examined for their coaggregation and biofilm-forming ability with leptospires in vitro. Among these, Azospirillum brasilense RMRCPB showed maximum interspecies coaggregation with leptospiral strains (>75%, visual score of +4). Other significant coaggregating isolates belonged to the genera Sphingomonas, Micrococcus, Brevundimonas, Acinetobacter and Paracoccus. Biofilms of leptospires in combination with A. brasilense RMRCPB showed high resistance to penicillin G, ampicillin and tetracycline (minimum bactericidal concentration ≥800 μg/mL) and tolerance to UV radiation and high temperature (up to 49°C). This study hypothesized that biofilm formation with A. brasilense protects the pathogenic Leptospira from adverse environmental conditions/stress. This coexistence of pathogenic Leptospira with other bacteria may be the key factor for its persistence and survival. However, the mechanism of biofilm formation by leptospires needs to be explored to help devise an appropriate control strategy and reduce transmission of leptospires. PMID:25962762

  8. Dynamics of development and dispersal in sessile microbial communities: examples from Pseudomonas aeruginosa and Pseudomonas putida model biofilms

    DEFF Research Database (Denmark)

    Klausen, M.; Gjermansen, Morten; Kreft, J.-U.;

    2006-01-01

    Surface-associated microbial communities in many cases display dynamic developmental patterns. Model biofilms formed by Pseudomonas aeruginosa and Pseudomonas putida in laboratory flow-chamber setups represent examples of such behaviour. Dependent on the experimental conditions the bacteria in...... organisms do not possess comprehensive genetic programs for biofilm development. Instead the bacteria appear to have evolved a number of different mechanisms to optimize surface colonization, of which they express a subset in response to the prevailing environmental conditions. These mechanisms include the...... ability to regulate cellular adhesiveness and migration in response to micro-environmental signals including those secreted by the bacteria themselves....

  9. Study on glass-forming ability and hydrogen storage properties of amorphous Mg60Ni30La10−xCox (x = 0, 4) alloys

    International Nuclear Information System (INIS)

    Mg60Ni30La10−xCox (x = 0, 4) amorphous alloys were prepared by rapid solidification, using a melt-spinning technique. X-ray diffraction and differential scanning calorimetry analysis were employed to measure their microstructure, thermal stability and glass-forming ability, and hydrogen storage properties were studied by means of PCTPro2000. Based on differential scanning calorimetry results, their glass-forming ability and thermal stability were investigated by Kissinger method, Lasocka curves and atomic cluster model, respectively. The results indicate that glass-forming ability, thermal properties and hydrogen storage properties in the Mg-rich corner of Mg–Ni–La–Co system alloys were enhanced by Co substitution for La. It can be found that the smaller activation energy (ΔΕ) and frequency factor (υ0), the bigger value of B (glass transition point in Lasocka curves), and higher glass-forming ability of Mg–Ni–La–Co alloys would be followed. In addition, atomic structure parameter (λ), deduced from atomic cluster model is valuable in the design of Mg–Ni–La–Co system alloys with good glass-forming ability. With an increase of Co content from 0 to 4, the hydrogen desorption capacity within 4000 s rises from 2.25 to 2.85 wt.% at 573 K. - Highlights: • Amorphous Mg60Ni30La10−xCox (x = 0 and 4) alloys were produced by melt spinning. • The GFA and hydrogen storage properties were enhanced by Co substitution for La. • With an increase of Co content, the hydrogen desorption capacity rises at 573 K

  10. Biofilm Fixed Film Systems

    Directory of Open Access Journals (Sweden)

    Dipesh Das

    2011-09-01

    Full Text Available The work reviewed here was published between 2008 and 2010 and describes research that involved aerobic and anoxic biofilm treatment of water pollutants. Biofilm denitrification systems are covered when appropriate. References catalogued here are divided on the basis of fundamental research area or reactor types. Fundamental research into biofilms is presented in two sections, Biofilm Measurement and Characterization and Growth and Modeling. The reactor types covered are: trickling filters, rotating biological contactors, fluidized bed bioreactors, submerged bed biofilm reactors, biological granular activated carbon, membrane bioreactors, and immobilized cell reactors. Innovative reactors, not easily classified, are then presented, followed by a section on biofilms on sand, soil and sediment.

  11. Extracellular matrix formation enhances the ability of Streptococcus pneumoniae to cause invasive disease.

    Directory of Open Access Journals (Sweden)

    Claudia Trappetti

    Full Text Available During infection, pneumococci exist mainly in sessile biofilms rather than in planktonic form, except during sepsis. However, relatively little is known about how biofilms contribute to pneumococcal pathogenesis. Here, we carried out a biofilm assay on opaque and transparent variants of a clinical serotype 19F strain WCH159. After 4 days incubation, scanning electron microscopy revealed that opaque biofilm bacteria produced an extracellular matrix, whereas the transparent variant did not. The opaque biofilm-derived bacteria translocated from the nasopharynx to the lungs and brain of mice, and showed 100-fold greater in vitro adherence to A549 cells than transparent bacteria. Microarray analysis of planktonic and sessile bacteria from transparent and opaque variants showed differential gene expression in two operons: the lic operon, which is involved in choline uptake, and in the two-component system, ciaRH. Mutants of these genes did not form an extracellular matrix, could not translocate from the nasopharynx to the lungs or the brain, and adhered poorly to A549 cells. We conclude that only the opaque phenotype is able to form extracellular matrix, and that the lic operon and ciaRH contribute to this process. We propose that during infection, extracellular matrix formation enhances the ability of pneumococci to cause invasive disease.

  12. Stenotrophomonas maltophilia biofilm reduction by Bdellovibrio exovorus.

    Science.gov (United States)

    Chanyi, Ryan M; Koval, Susan F; Brooke, Joanna S

    2016-06-01

    Stenotrophomonas maltophilia, a bacterium ubiquitous in the environment, is also an opportunistic, multidrug-resistant human pathogen that colonizes tissues and medical devices via biofilm formation. We investigated the ability of an isolate from sewage of the bacterial predator Bdellovibrio exovorus to disrupt preformed biofilms of 18 strains of S. maltophilia isolated from patients, hospital sink drains and water fountain drains. B. exovorus FFRS-5 preyed on all S. maltophilia strains in liquid co-cultures and was able to significantly disrupt the biofilms of 15 of the S. maltophilia strains tested, decreasing as much as 76.7% of the biofilm mass. The addition of ciprofloxacin and kanamycin in general reduced S. maltophilia biofilms but less than that of B. exovorus alone. Furthermore, when antibiotics and B. exovorus were used together, B. exovorus was still effective in the presence of ciprofloxacin whereas the addition of kanamycin reduced the effectiveness of B. exovorus. Overall, B. exovorus was able to decrease the mass of preformed biofilms of S. maltophilia in the presence of clinically relevant antibiotics demonstrating that the predator may prove to be a beneficial tool to reduce S. maltophilia environmental or clinically associated biofilms. PMID:26929093

  13. Influence of substrate micropatterning on biofilm growth

    Science.gov (United States)

    Koehler, Stephan; Li, Yiwei; Liu, Bi-Feng Liu; Weitz, David

    2015-11-01

    We culture triple reporter Bacillus Subtilis biofilm on micropatterned agar substrates. We track the biofilm development in terms of size, thickness, shape, and phenotype expression. For a tiling composed of elevated rectangles, we observe the biofilm develops an oval shape or triangular shape depending on the rectangle's aspect ratio and orientation. The motile cells are primarily located in the valleys between the rectangles and the matrix producing cells are mostly located on the rectangles. Wrinkles form at the edges of the elevated surfaces, and upon merging form channels centered on the elevated surface. After a few days, the spore-forming cells appear at the periphery. Since biofilms in nature grow on irregular surfaces, our work may provide insight into the complex patterns observed.

  14. Denitrifying activity of activated sludge in suspension and in biofilm

    OpenAIRE

    Cortez, Susana; Teixeira, P.; Oliveira, Rosário; Mota, M.

    2008-01-01

    A method based on measuring substrate depletion rate was developed to evaluate the denitrifying activity of activated sludge in suspension and in biofilm form in anoxic serum flasks. The adapted activated sludge inoculum was grown as biofilm in an anoxic rotating biological contactor (RBC). Acetate was used as external carbon source to obtain a carbon to nitrogen ratio (C/N) of 2. The results showed that the specific activity of cells in biofilm form was higher than in planktonic for...

  15. Assembly and development of the Pseudomonas aeruginosa biofilm matrix.

    OpenAIRE

    Luyan Ma; Matthew Conover; Haiping Lu; Parsek, Matthew R.; Kenneth Bayles; Wozniak, Daniel J.

    2009-01-01

    Virtually all cells living in multicellular structures such as tissues and organs are encased in an extracellular matrix. One of the most important features of a biofilm is the extracellular polymeric substance that functions as a matrix, holding bacterial cells together. Yet very little is known about how the matrix forms or how matrix components encase bacteria during biofilm development. Pseudomonas aeruginosa forms environmentally and clinically relevant biofilms and is a paradigm organis...

  16. Establishment and early succession of a multispecies biofilm composed of soil bacteria

    DEFF Research Database (Denmark)

    Burmølle, Mette; Hansen, Lars H; Sørensen, Søren J

    2007-01-01

    development of a biofilm flow model and use this system to establish an early (days 1-7) flow biofilm of soil bacteria from agricultural soil. It was possible to follow the succession in the early flow biofilm by denaturing gradient gel electrophoresis (DGGE) analysis, and it was demonstrated that the...... majority of strains present in the biofilm were culturable. We isolated and identified nine strains, all associated with unique DGGE profiles, and related their intrinsic phenotypes regarding monospecies biofilm formation in microtiter plates and planktonic growth characteristics to the appearance of the...... strains in the flow biofilm. The ability of the strains to attach to and establish biofilm in microtiter plates was reflected in their flow biofilm appearance, whereas no such reflection of the planktonic growth characteristics in the flow biofilm appearance was observed. One strain-specific synergistic...

  17. APPLICATION OF MIXING INDEX (IP FOR THE EVALUATION OF GEL-FORMING ABILITY IN MYOFIBRIL-PROTEIN GELS OF FISH PASTES

    Directory of Open Access Journals (Sweden)

    Hens Onibala*

    2010-06-01

    Full Text Available This study was aimed to evaluate the mixing process effectiveness of fish meat using a mixing index (Ip. Samples used were Tilapia, Oreochromis niloticus, Walleye pollack surimi, and a mixture of both. The ability of fish meat paste myofibril-protein to form gel was evaluated with a rigidity test and MHC distribution with SDS-PAGE. The results indicated that the mixing process effectiveness with salt was 3 minutes with an Ip close to 0. This was reflected by a rigidity value >MHC. Hence, this study concluded that mixing index could be used to evaluate the ability of fish meat gel formation.

  18. Staphylococcus epidermidis in orthopedic device infections: the role of bacterial internalization in human osteoblasts and biofilm formation.

    Directory of Open Access Journals (Sweden)

    Florent Valour

    Full Text Available BACKGROUND: Staphylococcus epidermidis orthopedic device infections are caused by direct inoculation of commensal flora during surgery and remain rare, although S. epidermidis carriage is likely universal. We wondered whether S. epidermidis orthopedic device infection strains might constitute a sub-population of commensal isolates with specific virulence ability. Biofilm formation and invasion of osteoblasts by S. aureus contribute to bone and joint infection recurrence by protecting bacteria from the host-immune system and most antibiotics. We aimed to determine whether S. epidermidis orthopedic device infection isolates could be distinguished from commensal strains by their ability to invade osteoblasts and form biofilms. MATERIALS AND METHODS: Orthopedic device infection S. epidermidis strains (n = 15 were compared to nasal carriage isolates (n = 22. Osteoblast invasion was evaluated in an ex vivo infection model using MG63 osteoblastic cells co-cultured for 2 hours with bacteria. Adhesion of S. epidermidis to osteoblasts was explored by a flow cytometric approach, and internalized bacteria were quantified by plating cell lysates after selective killing of extra-cellular bacteria with gentamicin. Early and mature biofilm formations were evaluated by a crystal violet microtitration plate assay and the Biofilm Ring Test method. RESULTS: No difference was observed between commensal and infective strains in their ability to invade osteoblasts (internalization rate 308+/-631 and 347+/-431 CFU/well, respectively. This low internalization rate correlated with a low ability to adhere to osteoblasts. No difference was observed for biofilm formation between the two groups. CONCLUSION: Osteoblast invasion and biofilm formation levels failed to distinguish S. epidermidis orthopedic device infection strains from commensal isolates. This study provides the first assessment of the interaction between S. epidermidis strains isolated from orthopedic

  19. Extracellular DNA as matrix component in microbial biofilms

    DEFF Research Database (Denmark)

    Chiang, Wen-Chi; Tolker-Nielsen, Tim

    2010-01-01

    to various persistent infections in humans and animals, and to a variety of complications in industry, where solid–water interfaces occur. Knowledge about the molecular mechanisms involved in biofilm formation is necessary for creating strategies to control biofilms. Recent studies have shown that......Bacteria in nature primarily live in surface-associated communities commonly known as biofilms. Because bacteria in biofilms, in many cases, display tolerance to host immune systems, antibiotics, and biocides, they are often difficult or impossible to eradicate. Biofilm formation, therefore, leads...... extracellular DNA is an important component of the extracellular matrix of microbial biofilms. The present chapter is focussed on extracellular DNA as matrix component in biofilms formed by Pseudomonas aeruginosa as an example from the Gram-negative bacteria, and Streptococcus and Staphylococcus as examples...

  20. Enhanced bone forming ability of SLA-treated Ti coated with a calcium phosphate thin film formed by e-beam evaporation

    International Nuclear Information System (INIS)

    With an electron-beam evaporation process, a calcium phosphate (Ca-P) thin film of ∼500 nm thick was deposited on sand blasted with large grits and acid etched (SLA) Ti without changing the typical morphology of the SLA surface. Dissolution behavior was investigated by measuring the amount of dissolved phosphate ions with ion chromatography after immersing the SLA Ti sample coated with a Ca-P film in 1 ml de-ionized water maintained at 37 0C for different periods of soaking time, and the surface morphology was observed with field emission scanning electron microscopy. The amount of phosphate ions increased quickly right after immersion but began to decrease after 2 days of immersion by redeposition with Ca ions as apatite, and the amount of biomimetic apatite increased with the extended soaking time. The Saos-2 cell was more attached on the coated surface, and the in vivo evaluation was that the Ca-P deposited SLA implant greatly improved the new bone formation ability.

  1. Enhanced bone forming ability of SLA-treated Ti coated with a calcium phosphate thin film formed by e-beam evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyeongil [Restorative Dentistry, School of Dental Medicine, University at Buffalo, NY 14214 (United States); Choi, Seong-Ho [Department of Periodontology, Research Institute for Periodontal Regeneration, College of Dentistry, Yonsei University, Seoul 120-752 (Korea, Republic of); Chung, Sung-Min; Li, Long-Hao [Dentium Clinic Implantium Institute, Seoul 135-879 (Korea, Republic of); Lee, In-Seop, E-mail: inseop@yonsei.ac.k [Atomic-Scale Surface Science Research Center, Yonsei University, Seoul 120-749 (Korea, Republic of)

    2010-08-01

    With an electron-beam evaporation process, a calcium phosphate (Ca-P) thin film of {approx}500 nm thick was deposited on sand blasted with large grits and acid etched (SLA) Ti without changing the typical morphology of the SLA surface. Dissolution behavior was investigated by measuring the amount of dissolved phosphate ions with ion chromatography after immersing the SLA Ti sample coated with a Ca-P film in 1 ml de-ionized water maintained at 37 {sup 0}C for different periods of soaking time, and the surface morphology was observed with field emission scanning electron microscopy. The amount of phosphate ions increased quickly right after immersion but began to decrease after 2 days of immersion by redeposition with Ca ions as apatite, and the amount of biomimetic apatite increased with the extended soaking time. The Saos-2 cell was more attached on the coated surface, and the in vivo evaluation was that the Ca-P deposited SLA implant greatly improved the new bone formation ability.

  2. Shaping the Growth Behaviour of Bacterial Aggregates in Biofilms

    CERN Document Server

    Melaugh, Gavin; Kragh, Kasper Nørskov; Irie, Yasuhiko; Roberts, Aled; Bjarnsholt, Thomas; Diggle, Steve P; Gordon, Vernita; Allen, Rosalind J

    2015-01-01

    Bacterial biofilms are usually assumed to originate from individual cells deposited on a surface. However, many biofilm-forming bacteria tend to aggregate in the planktonic phase meaning it is possible that many natural and infectious biofilms originate wholly or partially from pre-formed cell aggregates. Here, we use agent-based computer simulations to investigate the role of pre-formed aggregates in biofilm development. Focusing on the role of aggregate shape, we find that the degree of spreading of an aggregate on a surface can play a key role in determining its eventual fate during biofilm development. Specifically, initially spread aggregates perform better when competition with surrounding bacterial cells is low, while initially rounded aggregates perform better when competition is high. These contrasting outcomes are governed by a trade-off between aggregate surface area and height. Our results provide new insight into biofilm formation and development, and reveal new factors that may be at play in the...

  3. Essential factors of an integrated moving bed biofilm reactor-membrane bioreactor: Adhesion characteristics and microbial community of the biofilm.

    Science.gov (United States)

    Tang, Bing; Yu, Chunfei; Bin, Liying; Zhao, Yiliang; Feng, Xianfeng; Huang, Shaosong; Fu, Fenglian; Ding, Jiewei; Chen, Cuiqun; Li, Ping; Chen, Qianyu

    2016-07-01

    This work aims at revealing the adhesion characteristics and microbial community of the biofilm in an integrated moving bed biofilm reactor-membrane bioreactor, and further evaluating their variations over time. With multiple methods, the adhesion characteristics and microbial community of the biofilm on the carriers were comprehensively illuminated, which showed their dynamic variation along with the operational time. Results indicated that: (1) the roughness of biofilm on the carriers increased very quickly to a maximum value at the start-up stage, then, decreased to become a flat curve, which indicated a layer of smooth biofilm formed on the surface; (2) the tightly-bound protein and polysaccharide was the most important factor influencing the stability of biofilm; (3) the development of biofilm could be divided into three stages, and Gammaproteobacteria were the most dominant microbial species in class level at the last stage, which occupied the largest ratio (51.48%) among all microbes. PMID:27038266

  4. Pseudomonas fluorescens biofilms subjected to phage phiIBB-PF7A

    Directory of Open Access Journals (Sweden)

    Neubauer Peter

    2008-10-01

    Full Text Available Abstract Background Pseudomonas fluorescens is an important food spoilage organism, usually found in the form of biofilms. Bacterial biofilms are inherently resistant to a variety of antimicrobial agents, therefore alternative methods to biofilm control, such as bacteriophages (phages have been suggested. Phage behavior on biofilms is still poorly investigated and needs further understanding. Here we describe the application of phage ϕIBB-PF7, a newly isolated phage, to control P. fluorescens biofilms. The biofilms were formed under static or dynamic conditions and with or without renewal of medium. Results Conditions for biofilm formation influenced the feature of the biofilm and the morphology of P. fluorescens. Biomass removal due to phage activity varied between 63 and 91% depending on the biofilm age and the conditions under which the biofilm had been formed and phages applied. Removal of the biofilm by phage treatment was faster in younger biofilms, but the same number of surviving cells was detected in all tested biofilms, after only 4 h of treatment, even in older biofilms. Under static conditions, a 3 log higher number of phage progeny remained either inside the biofilm matrix or attached to the substratum surface than under dynamic conditions, pointing to the importance of experimental conditions for the efficacy of phage entrapment into the biofilm. Conclusion Phage ϕIBB-PF7A is highly efficient in removing P. fluorescens biofilms within a short time interval. The conditions of biofilm formation and applied during phage infection are critical for the efficacy of the sanitation process. The integration of phages into the biofilm matrix and their entrapment to the surface may be further beneficial factors when phage treatment is considered alone or in addition to chemical biocides in industrial environments where P. fluorescens causes serious spoilage.

  5. A Novel Computerized Cell Count Algorithm for Biofilm Analysis.

    Science.gov (United States)

    Klinger-Strobel, Mareike; Suesse, Herbert; Fischer, Dagmar; Pletz, Mathias W; Makarewicz, Oliwia

    2016-01-01

    Biofilms are the preferred sessile and matrix-embedded life form of most microorganisms on surfaces. In the medical field, biofilms are a frequent cause of treatment failure because they protect the bacteria from antibiotics and immune cells. Antibiotics are selected according to the minimal inhibitory concentration (MIC) based on the planktonic form of bacteria. Determination of the minimal biofilm eradicating concentration (MBEC), which can be up to 1,000-fold greater than the MIC, is not currently conducted as routine diagnostic testing, primarily because of the methodical hurdles of available biofilm assessing protocols that are time- and cost-consuming. Comparative analysis of biofilms is also limited as most quantitative methods such as crystal violet staining are indirect and highly imprecise. In this paper, we present a novel algorithm for assessing biofilm resistance to antibiotics that overcomes several of the limitations of alternative methods. This algorithm aims for a computer-based analysis of confocal microscope 3D images of biofilms after live/dead stains providing various biofilm parameters such as numbers of viable and dead cells and their vertical distributions within the biofilm, or biofilm thickness. The performance of this algorithm was evaluated using computer-simulated 2D and 3D images of coccal and rodent cells varying different parameters such as cell density, shading or cell size. Finally, genuine biofilms that were untreated or treated with nitroxoline or colistin were analyzed and the results were compared with quantitative microbiological standard methods. This novel algorithm allows a direct, fast and reproducible analysis of biofilms after live/dead staining. It performed well in biofilms of moderate cell densities in a 2D set-up however the 3D analysis remains still imperfect and difficult to evaluate. Nevertheless, this is a first try to develop an easy but conclusive tool that eventually might be implemented into routine

  6. Biofilm Fixed Film Systems

    OpenAIRE

    Dipesh Das; Yung-Tse Hung; Charles Moretti; Hasibul Hasan; Harvey Gullicks

    2011-01-01

    The work reviewed here was published between 2008 and 2010 and describes research that involved aerobic and anoxic biofilm treatment of water pollutants. Biofilm denitrification systems are covered when appropriate. References catalogued here are divided on the basis of fundamental research area or reactor types. Fundamental research into biofilms is presented in two sections, Biofilm Measurement and Characterization and Growth and Modeling. The reactor types covered are: trickling filters, r...

  7. Biophysics of Biofilm Infection

    OpenAIRE

    Stewart, Philip S.

    2014-01-01

    This article examines a likely basis of the tenacity of biofilm infections that has received relatively little attention: the resistance of biofilms to mechanical clearance. One way that a biofilm infection persists is by withstanding the flow of fluid or other mechanical forces that work to wash or sweep microorganisms out of the body. The fundamental criterion for mechanical persistence is that the biofilm failure strength exceeds the external applied stress. Mechanical failure of the biofi...

  8. Evaluation of the Inhibition of Culturable Enterococcus faecium, Escherichia coli, or Aeromonas hydrophilia by an Existing Drinking Water Biofilm

    Science.gov (United States)

    Experiments were conducted to determine if an existing biofilm could act as a inhibitor to introduced microorganisms, preventing them from being incorporated into the existing biofilm or forming a biofilm. Biofilm sampling coupons were challenged by a solution of a single indica...

  9. Laser Microbial Killing and Biofilm Disruption

    Science.gov (United States)

    Krespi, Yosef P.; Kizhner, Victor

    2009-06-01

    Objectives: To analyze the ability of NIR lasers to reduce bacterial load and demonstrate the capability of fiber-based Q-switched Nd:YAG laser disrupting biofilm. Study Design: NIR diode laser was tested in vitro and in vivo using pathogenic microorganisms (S. aureus, S. pneumoniae, P. aeruginosa). In addition biofilms were grown from clinical Pseudomonas isolates and placed in culture plates, screws, tympanostomy tubes and PET sutures. Methods: In the animal experiments acute rhinosinusitis model was created by packing the rabbit nose with bacteria soaked solution. The nasal pack was removed in two days and nose was exposed to laser irradiation. A 940 nm diode laser with fiber diffuser was used. Nasal cultures were obtained before and after the laser treatments. Animals were sacrificed fifteen days following laser treatment and bacteriologic/histologic results analyzed. Q-switched Nd:YAG laser generated shockwave pulses were delivered on biofilm using special probes over culture plates, screws, tubes, and PET sutures for the biofilm experiments. Results: Average of two log bacteria reduction was achieved with NIR laser compared to controls. Histologic studies demonstrated preservation of tissue integrity without significant damage to mucosa. Biofilms were imaged before, during and after treatment using a confocal microscope. During laser-generated shockwave application, biofilm was initially seen to oscillate and eventually break off. Large and small pieces of biofilm were totally and instantly removed from the surface to which they were attached in seconds. Conclusions: Significant bacterial reduction was achieved with NIR laser therapy in this experimental in vitro and animal study. In addition we disrupted Pseudomonas aeruginosa biofilms using Q-switched Nd:YAG laser and special probes generating plasma and shockwave. This new and innovative method of bacteria killing and biofilm disruption without injuring host tissue may have clinical application in the

  10. The role of biofilms in onychomycosis.

    Science.gov (United States)

    Gupta, Aditya K; Daigle, Deanne; Carviel, Jessie L

    2016-06-01

    Onychomycosis is a fungal infection of nails primarily caused by dermatophyte fungi. Fungi are traditionally understood as existing in the environment as planktonic organisms; however, recent advancements in microbiology suggest that fungi form biofilms-complex sessile microbial communities irreversibly attached to epithelial surfaces by means of an extracellular matrix. The extracellular matrix also acts as a protective barrier to the organisms within the biofilm. The biofilm is surprisingly resistant to injury and may act as a persistent source of infection possibly accounting for antifungal resistance in onychomycosis. PMID:27012826

  11. Cellular chain formation in Escherichia coli biofilms

    DEFF Research Database (Denmark)

    Vejborg, Rebecca Munk; Klemm, Per

    2009-01-01

    In this study we report on a novel structural phenotype in Escherichia coli biofilms: cellular chain formation. Biofilm chaining in E. coli K-12 was found to occur primarily by clonal expansion, but was not due to filamentous growth. Rather, chain formation was the result of intercellular......; type I fimbriae expression significantly reduced cellular chain formation, presumably by steric hindrance. Cellular chain formation did not appear to be specific to E coli K-12. Although many urinary tract infection (UTI) isolates were found to form rather homogeneous, flat biofilms, three isolates...

  12. Inhibitory effect of zinc oxide nanoparticles on pseudomonas aeruginosa biofilm formation

    OpenAIRE

    Mohammad Hassani Sangani; Mahboobeh Nakhaei Moghaddam; Mohammad Mahdi Forghanifard

    2015-01-01

    Objective(s): Bacterial biofilm formation causes many persistent and chronic infections. The matrix protects biofilm bacteria from exposure to innate immune defenses and antibiotic treatments. The purpose of this study was to evaluate the biofilm formation of clinical isolates of Pseudomonas aeruginosa and the activity of zinc oxide nanoparticles (ZnO NPs) on biofilm. Materials and Methods: After collecting bacteria from clinical samples of hospitalized patients, the ability of organisms were...

  13. Virulence factors in Proteus bacteria from biofilm communities of catheter-associated urinary tract infections.

    Science.gov (United States)

    Hola, Veronika; Peroutkova, Tereza; Ruzicka, Filip

    2012-07-01

    More than 40% of nosocomial infections are those of the urinary tract, most of these occurring in catheterized patients. Bacterial colonization of the urinary tract and catheters results not only in infection, but also various complications, such as blockage of catheters with crystalline deposits of bacterial origin, generation of gravels and pyelonephritis. The diversity of the biofilm microbial community increases with duration of catheter emplacement. One of the most important pathogens in this regard is Proteus mirabilis. The aims of this study were to identify and assess particular virulence factors present in catheter-associated urinary tract infection (CAUTI) isolates, their correlation and linkages: three types of motility (swarming, swimming and twitching), the ability to swarm over urinary catheters, biofilm production in two types of media, urease production and adherence of bacterial cells to various types of urinary tract catheters. We examined 102 CAUTI isolates and 50 isolates taken from stool samples of healthy people. Among the microorganisms isolated from urinary catheters, significant differences were found in biofilm-forming ability and the swarming motility. In comparison with the control group, the microorganisms isolated from urinary catheters showed a wider spectrum of virulence factors. The virulence factors (twitching motility, swimming motility, swarming over various types of catheters and biofilm formation) were also more intensively expressed. PMID:22533980

  14. Anti-Staphylococcal Biofilm Effects of Human Cathelicidin Peptides.

    Science.gov (United States)

    Mishra, Biswajit; Golla, Radha M; Lau, Kyle; Lushnikova, Tamara; Wang, Guangshun

    2016-01-14

    Staphylococcus aureus can live together in the form of biofilms to avoid elimination by the host. Thus, a useful strategy to counteract bacterial biofilms is to re-engineer human antimicrobial peptide LL-37 so that it can be used as a remedy for preventing and removing biofilms. This study reports antibiofilm effects of four human cathelicidin LL-37 peptides against community-associated and hospital isolated methicillin-resistant Staphylococcus aureus (MRSA) strains. Although the intact molecule LL-37 inhibited biofilm formation at low concentrations, it did not inhibit bacterial attachment nor disrupt preformed biofilms. However, two 17-residue peptides, GF-17 and 17BIPHE2, inhibited bacterial attachment, biofilm growth, and disrupted established biofilms. An inactive peptide RI-10 was used as a negative control. Our results obtained using the S. aureus mutants in a static biofilm model are consistent with the literature obtained in a flow cell biofilm model. Because 17BIPHE2 is the most effective biofilm disruptor with desired stability to proteases, it is a promising lead for developing new anti-MRSA biofilm agents. PMID:26819677

  15. Biofilms: A microbial home

    OpenAIRE

    Chandki, Rita; Banthia, Priyank; Banthia, Ruchi

    2011-01-01

    Microbial biofilms are mainly implicated in etiopathogenesis of caries and periodontal disease. Owing to its properties, these pose great challenges. Continuous and regular disruption of these biofilms is imperative for prevention and management of oral diseases. This essay provides a detailed insight into properties, mechanisms of etiopathogenesis, detection and removal of these microbial biofilms.

  16. Pseudomonas aeruginosa biofilm infections

    DEFF Research Database (Denmark)

    Tolker-Nielsen, Tim

    2014-01-01

    use of conventional antimicrobial compounds in many cases cannot eradicate biofilms, there is an urgent need to develop alternative measures to combat biofilm infections. The present review is focussed on the important opportunistic pathogen and biofilm model organism Pseudomonas aeruginosa. Initially...

  17. Influence of PEGylation on the ability of carboxymethyl-dextran to form complexes with α-lactalbumin.

    Science.gov (United States)

    Du, Juan; Reuhs, Brad L; Jones, Owen G

    2016-04-01

    Electrostatic interactions between α-lactalbumin (α-lac) and carboxymethyldextran (CMD) in acidic solutions lead to phase-separated complexes. By adding a non-ionic poly(ethylene glycol) (PEG) chain onto the reducing end of CMD, forming carboxymethyl-dextran-block-poly(ethylene glycol) (CMD-b-PEG), the PEG block was hypothesized to reduce interactions with α-lac and promote formation of a micelle-like complex structure. Formation of complexes between α-lac and CMD-b-PEG or α-lac and CMD was determined following acidification by light scattering and electrophoretic mobility. Phase separation, size, and structure of α-lac/CMD-b-PEG complexes were characterized by turbidimetry, dynamic light scattering, and electron microscopy, respectively. Complexes of α-lac/CMD-b-PEG formed at pH values near pH 6, while α-lac/CMD complexes formed at pH 5.5. Both CMD and CMD-b-PEG decreased the charge of α-lac below pH 5.5 and led to phase separation below pH 5. Shift in charge and the critical pH of phase separation were both sensitive to the α-lac to CMD ratio, while the relative amount of CMD-b-PEG did not significantly influence either. Hydrodynamic radii of α-lac/CMD-b-PEG complexes was between 11 and 20 nm, which increased with increasing α-lac to CMD-b-PEG ratio and with decreasing pH. Spheroidal structures of ∼10 nm were also observed in micrographs that were attributed to α-lac/CMD-b-PEG complexes. PMID:26593565

  18. The fundamental structural factor in determining the glass-forming ability and mechanical behavior in the Cu-Zr metallic glasses

    International Nuclear Information System (INIS)

    Research highlights: → A weak but significant hump in trend of the coordinate number and density was observed, respectively. → Our findings indicate our simulation is more accurate to describe the atomic structure of Cu-Zr MGs. The composition-structure-properties correlation was established. → And the effective structural unit for this correlation is the Cu-centered full icosahedra. - Abstract: Using the large-scale atomic/molecular massively parallel simulator, the quantitative composition-structure-properties (including glass-forming ability (GFA) and mechanical behavior) correlations in the Cu-Zr metallic glasses were established. The atomic-level origin of these correlations was tracked down. It was found that the Cu-centered full icosahedron is the microscopic factor that fundamentally influences both GFA and mechanical behavior. Our findings have implications for understanding the nature, forming ability and properties of metallic glasses, and for searching novel metallic glasses with unique functional properties.

  19. Removal of Dental Biofilms with an Ultrasonically Activated Water Stream.

    Science.gov (United States)

    Howlin, R P; Fabbri, S; Offin, D G; Symonds, N; Kiang, K S; Knee, R J; Yoganantham, D C; Webb, J S; Birkin, P R; Leighton, T G; Stoodley, P

    2015-09-01

    Acidogenic bacteria within dental plaque biofilms are the causative agents of caries. Consequently, maintenance of a healthy oral environment with efficient biofilm removal strategies is important to limit caries, as well as halt progression to gingivitis and periodontitis. Recently, a novel cleaning device has been described using an ultrasonically activated stream (UAS) to generate a cavitation cloud of bubbles in a freely flowing water stream that has demonstrated the capacity to be effective at biofilm removal. In this study, UAS was evaluated for its ability to remove biofilms of the cariogenic pathogen Streptococcus mutans UA159, as well as Actinomyces naeslundii ATCC 12104 and Streptococcus oralis ATCC 9811, grown on machine-etched glass slides to generate a reproducible complex surface and artificial teeth from a typodont training model. Biofilm removal was assessed both visually and microscopically using high-speed videography, confocal scanning laser microscopy (CSLM), and scanning electron microscopy (SEM). Analysis by CSLM demonstrated a statistically significant 99.9% removal of S. mutans biofilms exposed to the UAS for 10 s, relative to both untreated control biofilms and biofilms exposed to the water stream alone without ultrasonic activation (P naeslundii, and S. oralis biofilm removal from machine-etched glass and S. mutans from typodont surfaces with complex topography. Consequently, UAS technology represents a potentially effective method for biofilm removal and improved oral hygiene. PMID:26056055

  20. Biofilm mediated decontamination of pollutants from the environment

    Directory of Open Access Journals (Sweden)

    Arindam Mitra

    2016-01-01

    Full Text Available In this review, we highlight beneficial use of microbial biofilms in remediation of environmental pollutants by bioremediation. Bioremediation is an environment friendly, cost effective, sustainable technology that utilizes microbes to decontaminate and degrade a wide variety of pollutants into less harmful products. Relative to free-floating planktonic cells, microbes existing in biofilm mode are advantageous for bioremediation because of greater tolerance to pollutants, environmental stress and ability to degrade varied harsh pollutants via diverse catabolic pathways. In biofilm mode, microbes are immobilized in a self-synthesized matrix which offers protection from stress, contaminants and predatory protozoa. Contaminants ranging from heavy metals, petroleum, explosives, pesticides have been remediated using microbial consortia of biofilms. In the industry, biofilm based bioremediation is used to decontaminate polluted soil and groundwater. Here we discuss conventional and newer strategies utilizing biofilms in environmental remediation.