New rifamycins produced by a recombinant strain of Nocardia mediterranei.

Science.gov (United States)

Schupp, T; Traxler, P; Auden, J A

1981-08-01

A recombinant strain of Nocardia mediterranei was found to produce a number of new rifamycins which are structurally related to rifamycin S, rifamycin W and rifamycin G. This strain was derived from two Nocardia mediterranei mutants by intraspecific recombination.

[Isolation, identification and characterization of acid-producing strains from psychrotolerant biogas fermentation].

Science.gov (United States)

Wan, Yongqing; Zhang, Wei; Mandlaa; Tian, Ruihua; Wang, Ruigang; Duan, Kaihong

2015-11-04

The aim of this study was to screen acid-producing strains from the broth of psychrotolerant biogas fermentation and evaluate the acid-producing character of them. Acid-producing strains were isolated by a medium with methyl red at 4 degrees C in Petri dishes and identified by morphology observation and 16S rRNA sequencing. Moreover, the ability of hydrolysis of starch, fermentation of carbohydrates, liquefaction of gelatin and production of catalase were studied. Two acid-producing strains (FJ-8 and FJ-15) were isolated. The result of the 16S rRNA phylogenetic tree shows that FJ-8 and FJ-15 belong to Pseudomonas sp. and Shewanella sp., respectively. Both FJ-8 and FJ-15 could hydrolyze starch, liquidize gelatin and produce catalase. The optimum temperature for acid-producing of FJ-8 and FJ-15 is 15 degrees C and 20 degrees C, respectively. After 10 days cultivation at 4 degrees C, the concentration of acetic acid was 792 mg/L and 966 mg/L of FJ-8 and FJ-15, respectively. The selected strains, FJ-8 and FJ-15, have the potential to produce acids at low temperature.

Technological and safety properties of newly isolated GABA-producing Lactobacillus futsaii strains.

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Sanchart, C; Rattanaporn, O; Haltrich, D; Phukpattaranont, P; Maneerat, S

2016-09-01

To evaluate the technological and safety properties of Lactobacillus futsaii CS3 and CS5 isolated from Thai fermented shrimp products (Kung-Som) in order to develop a valuable gamma-aminobutyric acid (GABA)-producing starter culture. Both strains showed a high GABA-producing ability (>8 mg ml(-1) ) in MRS broth containing 20 mg ml(-1) monosodium glutamate (MSG) for 120 h. They also exhibited inhibitory activity against foodborne pathogens and spoilage bacteria. Cell surface hydrophobicity and proteolytic activity were observed in both strains. Strain CS3 survived better under simulated gastrointestinal tract conditions with only 1·5 log-units cell decrease over 8 h. Both strains showed the ability to deconjugate taurocholate and taurodeoxycholate acid. Neither virulence genes nor biogenic amine production was detected. Strain CS3 exhibited susceptibility to all tested antibiotics with the exception of vancomycin, while strain CS5 showed resistance to vancomycin, ampicillin and chloramphenicol. Based on the results obtained, Lact. futsaii CS3 is very promising as a GABA-producing and potentially probiotic starter culture strain for applications in functional fermented foods. This study focuses on the technological and safety characteristics of Lact. futsaii CS3 and CS5 including their high GABA-producing capacity for the first time. This provides a way of replacing chemical GABA by natural GABA using a GABA-producing starter culture candidate, at the same time offering the consumer new attractive food products. © 2016 The Society for Applied Microbiology.

Screening and characterization of Lactobacillus strains producing large amounts of exopolysaccharides

NARCIS (Netherlands)

Geel-Schutten, G.H. van; Flesch, F.; Brink, B. ten; Smith, M.R.; Dijkhuizen, L.

1998-01-01

A total of 182 Lactobacillus strains were screened for production of extracellular polysaccharides (EPS) by a new method: growth in liquid media with high sugar concentrations. Sixty EPS-positive strains were identified; 17 strains produced more than 100 mg/l soluble EPS. Sucrose was an excellent

Investigation of N-acyl homoserine lactone (AHL) molecule production in Gram-negative bacteria isolated from cooling tower water and biofilm samples.

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Haslan, Ezgi; Kimiran-Erdem, Ayten

2013-09-01

In this study, 99 Gram-negative rod bacteria were isolated from cooling tower water, and biofilm samples were examined for cell-to-cell signaling systems, N-acyl homoserine lactone (AHL) signal molecule types, and biofilm formation capacity. Four of 39 (10 %) strains isolated from water samples and 14 of 60 (23 %) strains isolated from biofilm samples were found to be producing a variety of AHL signal molecules. It was determined that the AHL signal molecule production ability and the biofilm formation capacity of sessile bacteria is higher than planktonic bacteria, and there was a statistically significant difference between the AHL signal molecule production of these two groups (p cooling tower water and biofilm samples produced different types of AHL signal molecules and that there were different types of AHL signal molecules in an AHL extract of bacteria. In the present study, it was observed that different isolates of the same strains did not produce the same AHLs or did not produce AHL molecules, and bacteria known as AHL producers did not produce AHL. These findings suggest that detection of signal molecules in bacteria isolated from cooling towers may contribute to prevention of biofilm formation, elimination of communication among bacteria in water systems, and blockage of quorum-sensing controlled virulence of these bacteria.

NEW STRAINS PRODUCER OF BIOBUTANOL. ІІ. RENEWABLE LIGNOCELLULOSE FERMENTATION

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Tigunova O. O.

2014-08-01

Full Text Available The purpose of our work was to study generic and specific affinity of domestic strainsproducers, comparative productivity butanol strains-producers screening, fermentation of sugars being a part of renewable lignocelluloses raw materials and to determine the conditions for the butanol yield increasing. The objects of research were strains Clostridium acetobutylicum ІМВ В-7407 (IFBG C6H, IFBG C4B and IFBG C7P from «Collection microorganism’s stains and plants line for food and agriculture biotechnology» of Institute of Food Biotechnology and Genomics of the National Academy of Sciences of Ukraine. It was determined that domestic butanol-producing strains were relatively more productive and might be promising for improvement technology of butanol production.

[Morphological characteristics and physiological properties of aflatoxin B1 producing and non-producing Aspergillus flavus strains].

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Kogbo, W; Lemarinier, S; Boutibonnes, P

1985-09-01

Comparison between about 80 strains of Aspergillus flavus, belonging to the series flavus and oryzae, obtained from international collections but also isolated from French or African substrates revealed the following observations: 1. Cultural and morphological characteristics of toxicogenic and atoxicogenic strains of A. flavus are similar. However, the former produce a diffusible yellow pigment in 83% of isolates. 2. The two groups of conidiospores have the same resistance to UV irradiation (254 nm, 5 and 10 min). All the strains are equally sensitive to 4 antifungal antibiotics: nystatine, ketoconazole, clotrimazole and amphotericine. 3. A difference was seen in the capacity to produce enzymes as alpha-galactosidase, beta-galactosidase and beta-glucosidase, implicated in the glucid metabolism. The specific hydrolytic activity has been confirmed by the characterization of a large amount of beta-galactosidase and by a diauxic growth on glucose medium supplemented by lactose. Possible relationship between these characters and aflatoxin B1 production by A. flavus strains is discussed.

Detection, Characterization, and Biological Effect of Quorum-Sensing Signaling Molecules in Peanut-Nodulating Bradyrhizobia

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Walter Giordano

2012-03-01

Full Text Available Bacteria of the genus Bradyrhizobium are able to establish a symbiotic relationship with peanut (Arachis hypogaea root cells and to fix atmospheric nitrogen by converting it to nitrogenous compounds. Quorum sensing (QS is a cell-cell communication mechanism employed by a variety of bacterial species to coordinate behavior at a community level through regulation of gene expression. The QS process depends on bacterial production of various signaling molecules, among which the N-acylhomoserine lactones (AHLs are most commonly used by Gram-negative bacteria. Some previous reports have shown the production of QS signaling molecules by various rhizobia, but little is known regarding mechanisms of communication among peanut-nodulating strains. The aims of this study were to identify and characterize QS signals produced by peanut-nodulating bradyrhizobial strains and to evaluate their effects on processes related to cell interaction. Detection of AHLs in 53 rhizobial strains was performed using the biosensor strains Agrobacterium tumefaciens NTL4 (pZLR4 and Chromobacterium violaceum CV026 for AHLs with long and short acyl chains, respectively. None of the strains screened were found to produce AHLs with short acyl chains, but 14 strains produced AHLs with long acyl chains. These 14 AHL-producing strains were further studied by quantification of β-galactosidase activity levels (AHL-like inducer activity in NTL4 (pZLR4. Strains displaying moderate to high levels of AHL-like inducer activity were subjected to chemical identification of signaling molecules by high-performance liquid chromatography coupled to mass spectrometry (LC-MS/MS. For each AHL-producing strain, we found at least four different AHLs, corresponding to N-hexanoyl-DL-homoserine lactone (C6, N-(3-oxodecanoyl-L-homoserine lactone (3OC10, N-(3-oxododecanoyl-L-homoserine lactone (3OC12, and N-(3-oxotetradecanoyl-L-homoserine lactone (3OC14. Biological roles of 3OC10, 3OC12, and 3OC14 AHLs

A rapid colorimetric screening method for vanillic acid and vanillin-producing bacterial strains.

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Zamzuri, N A; Abd-Aziz, S; Rahim, R A; Phang, L Y; Alitheen, N B; Maeda, T

2014-04-01

To isolate a bacterial strain capable of biotransforming ferulic acid, a major component of lignin, into vanillin and vanillic acid by a rapid colorimetric screening method. For the production of vanillin, a natural aroma compound, we attempted to isolate a potential strain using a simple screening method based on pH change resulting from the degradation of ferulic acid. The strain Pseudomonas sp. AZ10 UPM exhibited a significant result because of colour changes observed on the assay plate on day 1 with a high intensity of yellow colour. The biotransformation of ferulic acid into vanillic acid by the AZ10 strain provided the yield (Yp/s ) and productivity (Pr ) of 1·08 mg mg(-1) and 53·1 mg L(-1) h(-1) , respectively. In fact, new investigations regarding lignin degradation revealed that the strain was not able to produce vanillin and vanillic acid directly from lignin; however, partially digested lignin by mixed enzymatic treatment allowed the strain to produce 30·7 mg l(-1) and 1·94 mg l(-1) of vanillic acid and biovanillin, respectively. (i) The rapid colorimetric screening method allowed the isolation of a biovanillin producer using ferulic acid as the sole carbon source. (ii) Enzymatic treatment partially digested lignin, which could then be utilized by the strain to produce biovanillin and vanillic acid. To the best of our knowledge, this is the first study reporting the use of a rapid colorimetric screening method for bacterial strains producing vanillin and vanillic acid from ferulic acid. © 2013 The Society for Applied Microbiology.

Selection of tannase-producing Aspergillus niger strains

OpenAIRE

Pinto,Gustavo A.S.; Leite,Selma G.F.; Terzi,Selma C.; Couri,Sonia

2001-01-01

The aim of this work was to select strains of Aspergillus niger for tannase production. Growth of colonies in plates with tannic acid-containing medium indicated their ability to synthesize tannase. Tannase activity was also measured in solid-state fermentation. A. niger 11T25A5 was the best tannase producer (67.5 U.g-1/72 hours of fermentation).

Cafestol Inhibits Cyclic-Strain-Induced Interleukin-8, Intercellular Adhesion Molecule-1, and Monocyte Chemoattractant Protein-1 Production in Vascular Endothelial Cells

Science.gov (United States)

Hao, Wen-Rui; Sung, Li-Chin; Chen, Chun-Chao; Chen, Jin-Jer

2018-01-01

Moderate coffee consumption is inversely associated with cardiovascular disease mortality; however, mechanisms underlying this causal effect remain unclear. Cafestol, a diterpene found in coffee, has various properties, including an anti-inflammatory property. This study investigated the effect of cafestol on cyclic-strain-induced inflammatory molecule secretion in vascular endothelial cells. Cells were cultured under static or cyclic strain conditions, and the secretion of inflammatory molecules was determined using enzyme-linked immunosorbent assay. The effects of cafestol on mitogen-activated protein kinases (MAPK), heme oxygenase-1 (HO-1), and sirtuin 1 (Sirt1) signaling pathways were examined using Western blotting and specific inhibitors. Cafestol attenuated cyclic-strain-stimulated intercellular adhesion molecule-1 (ICAM-1), monocyte chemoattractant protein- (MCP-) 1, and interleukin- (IL-) 8 secretion. Cafestol inhibited the cyclic-strain-induced phosphorylation of extracellular signal-regulated kinase and p38 MAPK. By contrast, cafestol upregulated cyclic-strain-induced HO-1 and Sirt1 expression. The addition of zinc protoporphyrin IX, sirtinol, or Sirt1 silencing (transfected with Sirt1 siRNA) significantly attenuated cafestol-mediated modulatory effects on cyclic-strain-stimulated ICAM-1, MCP-1, and IL-8 secretion. This is the first study to report that cafestol inhibited cyclic-strain-induced inflammatory molecule secretion, possibly through the activation of HO-1 and Sirt1 in endothelial cells. The results provide valuable insights into molecular pathways that may contribute to the effects of cafestol. PMID:29854096

Isolation and partial characterization of pigment-like antibiotics produced by a new strain of Streptosporangium isolated from an Algerian soil.

Science.gov (United States)

Boudjella, H; Bouti, K; Zitouni, A; Mathieu, F; Lebrihi, A; Sabaou, N

2007-07-01

Identification of a new actinomycete strain Sg3, belonging to the genus Streptosporangium and partial characterization of the produced antibacterial activities. The strain Sg3 was isolated from an Algerian Saharan soil and identified by morphological, chemotaxonomic and phylogenetic analyses to the genus Streptosporangium. The comparison of its physiological characteristics with those of known species of Streptosporangium showed significant differences with the nearest species Streptosporangium carneum. Analysis of the 16S rDNA sequence of strain Sg3 showed a similarity level ranging between 97% and 98.8% within Streptosporangium species, with S. carneum the most closely related. Strain Sg3 showed a red coloured antibacterial activity against gram-positive bacteria on several culture media. The purification of the red pigment by chromatographic methods led to the isolation of three active products. The (1)H nuclear magnetic resonance (NMR), mass, infrared (IR) and ultraviolet-visible (UV-VIS) data of these molecules strongly suggested that they belonged to the quinone-anthracycline group with three or more rings. Strain Sg3 represents a distinct phyletic line suggesting a new genomic species. It produces antibacterial activities identified as quinone-anthracycline aromatics. The quinone-anthracycline antibiotics are known for their antimicrobial and antineoplastic activities and are used in chemotherapy for the treatment of many cancer diseases. The present work constitutes the first stage of a whole series of studies to be realized on these antibiotics before arriving at a possible application.

Clostridium botulinum strains producing BoNT/F4 or BoNT/F5.

Science.gov (United States)

Raphael, Brian H; Bradshaw, Marite; Kalb, Suzanne R; Joseph, Lavin A; Lúquez, Carolina; Barr, John R; Johnson, Eric A; Maslanka, Susan E

2014-05-01

Botulinum neurotoxin type F (BoNT/F) may be produced by Clostridium botulinum alone or in combination with another toxin type such as BoNT/A or BoNT/B. Type F neurotoxin gene sequences have been further classified into seven toxin subtypes. Recently, the genome sequence of one strain of C. botulinum (Af84) was shown to contain three neurotoxin genes (bont/F4, bont/F5, and bont/A2). In this study, eight strains containing bont/F4 and seven strains containing bont/F5 were examined. Culture supernatants produced by these strains were incubated with BoNT/F-specific peptide substrates. Cleavage products of these peptides were subjected to mass spectral analysis, allowing detection of the BoNT/F subtypes present in the culture supernatants. PCR analysis demonstrated that a plasmid-specific marker (PL-6) was observed only among strains containing bont/F5. Among these strains, Southern hybridization revealed the presence of an approximately 242-kb plasmid harboring bont/F5. Genome sequencing of four of these strains revealed that the genomic backgrounds of strains harboring either bont/F4 or bont/F5 are diverse. None of the strains analyzed in this study were shown to produce BoNT/F4 and BoNT/F5 simultaneously, suggesting that strain Af84 is unusual. Finally, these data support a role for the mobility of a bont/F5-carrying plasmid among strains of diverse genomic backgrounds.

Characterisation of the exopolysaccharide (EPS)-producing Lactobacillus paraplantarum BGCG11 and its non-EPS producing derivative strains as potential probiotics.

Science.gov (United States)

Nikolic, Milica; López, Patricia; Strahinic, Ivana; Suárez, Ana; Kojic, Milan; Fernández-García, María; Topisirovic, Ljubisa; Golic, Natasa; Ruas-Madiedo, Patricia

2012-08-17

Traditional fermented foods are the best source for the isolation of strains with specific traits to act as functional starters and to keep the biodiversity of the culture collections. Besides, these strains could be used in the formulation of foods claimed to promote health benefits, i.e. those containing probiotic microorganisms. For the rational selection of strains acting as probiotics, several in vitro tests have been proposed. In the current study, we have characterized the probiotic potential of the strain Lactobacillus paraplantarum BGCG11, isolated from a Serbian soft, white, homemade cheese, which is able to produce a "ropy" exopolysaccharide (EPS). Three novobiocin derivative strains, which have lost the ropy phenotype, were characterized as well in order to determine the putative role of the EPS in the probiotic potential. Under chemically gastrointestinal conditions, all strains were able to survive around 1-2% (10(6)-10(7)cfu/ml cultivable bacteria) only when they were included in a food matrix (1% skimmed milk). The strains were more resistant to acid conditions than to bile salts and gastric or pancreatic enzymes, which could be due to a pre-adaptation of the parental strain to acidic conditions in the cheese habitat. The ropy EPS did not improve the survival of the producing strain. On the contrary, the presence of an EPS layer surrounding the strain BGCG11 hindered its adhesion to the three epithelial intestinal cell lines tested, since the adhesion of the three non-ropy derivatives was higher than the parental one and also than that of the reference strain Lactobacillus rhamnosus GG. Aiming to propose a potential target application of these strains as probiotics, the cytokine production of peripheral blood mononuclear cells (PBMC) was analyzed. The EPS-producing L. paraplantarum BGCG11 strain showed an anti-inflammatory or immunosuppressor profile whereas the non-ropy derivative strains induced higher pro-inflammatory response. In addition, when

Isolation and identification of biocellulose-producing bacterial strains from Malaysian acidic fruits.

Science.gov (United States)

Voon, W W Y; Rukayadi, Y; Meor Hussin, A S

2016-05-01

Biocellulose (BC) is pure extracellular cellulose produced by several species of micro-organisms that has numerous applications in the food, biomedical and paper industries. However, the existing biocellulose-producing bacterial strain with high yield was limited. The aim of this study was to isolate and identify the potential biocellulose-producing bacterial isolates from Malaysian acidic fruits. One hundred and ninety-three bacterial isolates were obtained from 19 local acidic fruits collected in Malaysia and screened for their ability to produce BC. A total of 15 potential bacterial isolates were then cultured in standard Hestrin-Schramm (HS) medium statically at 30°C for 2 weeks to determine the BC production. The most potent bacterial isolates were identified using 16S rRNA gene sequence analysis, morphological and biochemical characteristics. Three new and potent biocellulose-producing bacterial strains were isolated from soursop fruit and identified as Stenotrophomonas maltophilia WAUPM42, Pantoea vagans WAUPM45 and Beijerinckia fluminensis WAUPM53. Stenotrophomonas maltophilia WAUPM42 was the most potent biocellulose-producing bacterial strain that produced the highest amount of BC 0·58 g l(-1) in standard HS medium. Whereas, the isolates P. vagans WAUPM45 and B. fluminensis WAUPM53 showed 0·50 and 0·52 g l(-1) of BC production, respectively. Biocellulose (BC) is pure extracellular cellulose that is formed by many micro-organisms in the presence of carbon source and acidic condition. It can replace plant-based cellulose in multifarious applications due to its unique characteristics. In this study, three potential biocellulose-producing bacterial strains were obtained from Malaysian acidic fruits and identified as Stenotrophomonas maltophilia WAUPM42, Pantoea vagans WAUPM45 and Beijerinckia fluminensis WAUPM53. This study reports for the first time the new biocellulose-producing bacterial strains isolated from Malaysian acidic fruits. © 2016 The

Lichenysin is produced by most Bacillus licheniformis strains.

Science.gov (United States)

Madslien, E H; Rønning, H T; Lindbäck, T; Hassel, B; Andersson, M A; Granum, P E

2013-10-01

The aim of this study was to elucidate the prevalence of lichenysin production in Bacillus licheniformis and to see whether this feature was restricted to certain genotypes. Secondly, we wanted to see whether cytotoxicity reflected the measured levels of lichenysin. Fifty-three genotyped strains of B. licheniformis, representing a wide variety of sources, were included. lchAA gene fragments were detected in all strains by polymerase chain reaction (PCR). All 53 strains produced lichenysins with four molecular masses as confirmed by LC-MS/MS (liquid chromatography-tandem mass spectrometry) analysis. The amounts of lichenysin varied more than two orders of magnitude between strains and were irrespective of genotype. Finally, there was a strong association between lichenysin concentrations and toxicity towards boar spermatozoa, erythrocytes and Vero cells. Lichenysin synthesis was universal among the 53 B. licheniformis strains examined. The quantities varied considerably between strains, but were not specifically associated with genotype. Cytotoxicity was evident at lichenysin concentrations above 10 μg ml(-1) , which is in accordance with previous studies. This study might be of interest to those working on B. licheniformis for commercial use as well as for authorities who make risk assessments of B. licheniformis when used as a food and feed additive. © 2013 The Society for Applied Microbiology.

Comparison of Biochemical Activities between High and Low Lipid-Producing Strains of Mucor circinelloides: An Explanation for the High Oleaginicity of Strain WJ11.

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Xin Tang

Full Text Available The oleaginous fungus, Mucor circinelloides, is one of few fungi that produce high amounts of γ-linolenic acid (GLA; however, it usually only produces <25% lipid. Nevertheless, a new strain (WJ11 isolated in this laboratory can produce lipid up to 36% (w/w cell dry weight (CDW. We have investigated the potential mechanism of high lipid accumulation in M. circinelloides WJ11 by comparative biochemical analysis with a low lipid-producing strain, M. circinelloides CBS 277.49, which accumulates less than 15% (w/w lipid. M. circinelloides WJ11 produced more cell mass than that of strain CBS 277.49, although with slower glucose consumption. In the lipid accumulation phase, activities of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase in strain WJ11 were greater than in CBS 277.49 by 46% and 17%, respectively, and therefore may provide more NADPH for fatty acid biosynthesis. The activities of NAD+:isocitrate dehydrogenase and NADP+:isocitrate dehydrogenase, however, were 43% and 54%, respectively, lower in WJ11 than in CBS 277.49 and may retard the tricarboxylic acid cycle and thereby provide more substrate for ATP:citrate lyase (ACL to produce acetyl-CoA. Also, the activities of ACL and fatty acid synthase in the high lipid-producing strain, WJ11, were 25% and 56%, respectively, greater than in strain CBS 277.49. These enzymes may therefore cooperatively regulate the fatty acid biosynthesis in these two strains.

Comparison of Biochemical Activities between High and Low Lipid-Producing Strains of Mucor circinelloides: An Explanation for the High Oleaginicity of Strain WJ11.

Science.gov (United States)

Tang, Xin; Chen, Haiqin; Chen, Yong Q; Chen, Wei; Garre, Victoriano; Song, Yuanda; Ratledge, Colin

2015-01-01

The oleaginous fungus, Mucor circinelloides, is one of few fungi that produce high amounts of γ-linolenic acid (GLA); however, it usually only produces <25% lipid. Nevertheless, a new strain (WJ11) isolated in this laboratory can produce lipid up to 36% (w/w) cell dry weight (CDW). We have investigated the potential mechanism of high lipid accumulation in M. circinelloides WJ11 by comparative biochemical analysis with a low lipid-producing strain, M. circinelloides CBS 277.49, which accumulates less than 15% (w/w) lipid. M. circinelloides WJ11 produced more cell mass than that of strain CBS 277.49, although with slower glucose consumption. In the lipid accumulation phase, activities of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase in strain WJ11 were greater than in CBS 277.49 by 46% and 17%, respectively, and therefore may provide more NADPH for fatty acid biosynthesis. The activities of NAD+:isocitrate dehydrogenase and NADP+:isocitrate dehydrogenase, however, were 43% and 54%, respectively, lower in WJ11 than in CBS 277.49 and may retard the tricarboxylic acid cycle and thereby provide more substrate for ATP:citrate lyase (ACL) to produce acetyl-CoA. Also, the activities of ACL and fatty acid synthase in the high lipid-producing strain, WJ11, were 25% and 56%, respectively, greater than in strain CBS 277.49. These enzymes may therefore cooperatively regulate the fatty acid biosynthesis in these two strains.

A rapid enzymatic assay for high-throughput screening of adenosine-producing strains

Science.gov (United States)

Dong, Huina; Zu, Xin; Zheng, Ping; Zhang, Dawei

2015-01-01

Adenosine is a major local regulator of tissue function and industrially useful as precursor for the production of medicinal nucleoside substances. High-throughput screening of adenosine overproducers is important for industrial microorganism breeding. An enzymatic assay of adenosine was developed by combined adenosine deaminase (ADA) with indophenol method. The ADA catalyzes the cleavage of adenosine to inosine and NH3, the latter can be accurately determined by indophenol method. The assay system was optimized to deliver a good performance and could tolerate the addition of inorganic salts and many nutrition components to the assay mixtures. Adenosine could be accurately determined by this assay using 96-well microplates. Spike and recovery tests showed that this assay can accurately and reproducibly determine increases in adenosine in fermentation broth without any pretreatment to remove proteins and potentially interfering low-molecular-weight molecules. This assay was also applied to high-throughput screening for high adenosine-producing strains. The high selectivity and accuracy of the ADA assay provides rapid and high-throughput analysis of adenosine in large numbers of samples. PMID:25580842

[Genetic modification of Methylobacterium extorquens G10 producer strain of polyhydroxybutyrate].

Science.gov (United States)

Fedorov, D N; Zamakhaeva, S A; Ezhov, V A; Doronina, N V; Trotsenko, Iu A

2014-01-01

The effect of the increased copy number of polyhydroxybutyrate (PHB) biosynthesis genes in pink-pigmented methylobacterium Methylobacterium extorquens G10 on properties of the biopolymer was studied. The activity of poly-3-hydroxybutyril-synthase (PHB-synthase) was shown to increase and the molecular weight of synthesized PHB decreases twofold (150 --> 79 kDa) after insertion of extra copies of phaC and phaCAB genes into cells of the producer strain, whereas the physicochemical properties of the plastic changed insignificantly. White mutant M. extorquens G10-W with disrupted synthesis of the carotenoid pigment (defect by the crtI gene, which codes for phytoene desaturase) was established to have the same rate of growth and level of PHB accumulation as the initial strain G10. The G10-W strain is a promising producer of PHB, with decreased expenses for purification and PHB biosynthesis.

Intercellular communication in Helicobacter pylori: luxS is essential for the production of an extracellular signaling molecule.

Science.gov (United States)

Forsyth, M H; Cover, T L

2000-06-01

Individual bacteria of numerous species can communicate and coordinate their actions via the production, release, and detection of extracellular signaling molecules. In this study, we used the Vibrio harveyi luminescence bioassay to determine whether Helicobacter pylori produces such a factor. Cell-free conditioned media from H. pylori strains 60190 and 26695 each induced >100-fold-greater luminescence in V. harveyi than did sterile culture medium. The H. pylori signaling molecule had a molecular mass of 100-fold-greater luminescence in the V. harveyi bioassay than did conditioned medium from either mutant strain. Production of the signaling molecule was restored in an H. pylori luxS null mutant strain by complementation with a single intact copy of luxS placed in a heterologous site on the chromosome. In addition, Escherichia coli DH5alpha produced autoinducer activity following the introduction of an intact copy of luxS from H. pylori. Production of the signaling molecule by H. pylori was growth phase dependent, with maximal production occurring in the mid-exponential phase of growth. Transcription of H. pylori vacA also was growth phase dependent, but this phenomenon was not dependent on luxS activity. These data indicate that H. pylori produces an extracellular signaling molecule related to AI-2 from V. harveyi. We speculate that this signaling molecule may play a role in regulating H. pylori gene expression.

Molecules produced by probiotics prevent enteric colibacillosis in pigs.

Science.gov (United States)

Nordeste, Ricardo; Tessema, Akalate; Sharma, Sapana; Kovač, Zlatko; Wang, Chuan; Morales, Rocio; Griffiths, Mansel William

2017-11-15

With the advent of antimicrobial resistance in animal pathogens, novel methods to combat infectious diseases are being sought. Among these, probiotics have been proposed as a means of promoting animal health but problems with their use has been reported. Research has demonstrated that bioactive molecules produced during the growth of certain probiotics interfere with bacterial cell-to-cell communication, which consequently results in an attenuation of virulence in a number of pathogens, including E. coli. The objective of this study was to determine the efficacy of the bioactive molecules, termed proteobiotics, produced by Lactobacillus acidophilus in preventing enterotoxigenic E, coli (ETEC) infection in pigs, which is the etiological agent for enteric colibacillosis, a common disease of nursing and young pigs. To achieve this, piglets were fed a preparation of the bioactive at four levels: 0, 0.5×, 1.0× and 2.0× for 7 days prior to challenge with E. coli K88. There were 36 pigs (18 gilts and 18 barrows) per treatment, resulting in 144 piglets in total for the study. Each pen had 6 piglets (3 gilts and 3 barrows). Only piglets with no physical abnormality or conditions were used in the trial and intact male piglets and ridglings were excluded. The bioactive continued to be fed to the pigs post-challenge. Based of fecal and demeanour scores, pigs fed the low and high dose of the proteobiotic were significanlty less likely to show symptoms of illness than pigs fed no bioactive. While not being significant, the weight gain of pigs given the proteobiotics was improved. At day 4 following challenge, almost 50% of piglets that did not receive the proteobiotic were shedding ETEC in their feces, compared with about 15% of animals receiving the supplement. There was also an indication that the proteobiotics reduced colonization of the ileum by E. coli K88 and improved gut health. This study indicates that the bioactive molecules produced by L. acidophilus reduces

Developing techniques for the utilization of Planctomycetes as producers of bioactive molecules

Directory of Open Access Journals (Sweden)

Olga Jeske

2016-08-01

Full Text Available Planctomycetes are conspicuous, ubiquitous, environmentally important bacteria. They can attach to various surfaces in aquatic habitats and form biofilms. Their unique FtsZ-independent budding cell division mechanism is associated with slow growth and doubling times from six hours up to one month. Despite this putative disadvantage in the struggle to colonize surfaces, Planctomycetes are frequently associated with aquatic phototrophic organisms such as diatoms, cyanobacteria or kelp, whereby Planctomycetes can account for up to 50 % of the biofilm-forming bacterial population. Consequently, Planctomycetes were postulated to play an important role in carbon utilization, for example as scavengers after phototrophic blooms. However, given their observed slow growth, such findings are surprising since other faster- growing heterotrophs tend to colonize similar ecological niches. Accordingly, Planctomycetes were suspected to produce antibiotics for habitat protection in response to the attachment on phototrophs. Recently, we demonstrated their genomic potential to produce nonribosomal peptides, polyketides, bacteriocins, and terpenoids that might have antibiotic activities. In this study, we describe the development of a pipeline that consists of tools and procedures to cultivate Planctomycetes for the production of antimicrobial compounds in a chemically- defined medium and a procedure to chemically mimic their interaction with bacteria such as for example Cyanobacteria. We evaluated and adjusted screening assays to allow the hunt for planctomycetal antibiotics. As proof of principle, we demonstrate antimicrobial activities of planctomycetal extracts from Planctopirus limnophila DSM 3776, Rhodopirellula baltica DSM 10527, and the recently isolated strain Pan216. By combining UV/Vis and high resolution mass spectrometry data from High-Performance Liquid Chromatography fractionations with growth inhibition of indicator strains, we were able to assign

Aflatoxin B1 producing potential of Aspergillus flavus strains isolated ...

African Journals Online (AJOL)

STORAGESEVER

2009-07-20

Jul 20, 2009 ... consumption of aflatoxin contaminated food and feed. (Reddy and ..... intervals by artificial inoculation of A. parasiticus on rice grains. ... additive for culture media for rapid identification of aflatoxin producing. Aspergillus strains ...

Variable characteristics of bacteriocin-producing Streptococcus salivarius strains isolated from Malaysian subjects.

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Abdelahhad Barbour

Full Text Available BACKGROUND: Salivaricins are bacteriocins produced by Streptococcus salivarius, some strains of which can have significant probiotic effects. S. salivarius strains were isolated from Malaysian subjects showing variable antimicrobial activity, metabolic profile, antibiotic susceptibility and lantibiotic production. METHODOLOGY/PRINCIPAL FINDINGS: In this study we report new S. salivarius strains isolated from Malaysian subjects with potential as probiotics. Safety assessment of these strains included their antibiotic susceptibility and metabolic profiles. Genome sequencing using Illumina's MiSeq system was performed for both strains NU10 and YU10 and demonstrating the absence of any known streptococcal virulence determinants indicating that these strains are safe for subsequent use as probiotics. Strain NU10 was found to harbour genes encoding salivaricins A and 9 while strain YU10 was shown to harbour genes encoding salivaricins A3, G32, streptin and slnA1 lantibiotic-like protein. Strain GT2 was shown to harbour genes encoding a large non-lantibiotic bacteriocin (salivaricin-MPS. A new medium for maximum biomass production buffered with 2-(N-morpholinoethanesulfonic acid (MES was developed and showed better biomass accumulation compared with other commercial media. Furthermore, we extracted and purified salivaricin 9 (by strain NU10 and salivaricin G32 (by strain YU10 from S. salivarius cells grown aerobically in this medium. In addition to bacteriocin production, S. salivarius strains produced levan-sucrase which was detected by a specific ESI-LC-MS/MS method which indicates additional health benefits from the developed strains. CONCLUSION: The current study established the bacteriocin, levan-sucrase production and basic safety features of S. salivarius strains isolated from healthy Malaysian subjects demonstrating their potential for use as probiotics. A new bacteriocin-production medium was developed with potential scale up application for

Recovery of succinic acid produced by fermentation of a metabolically engineered Mannheimia succiniciproducens strain.

Science.gov (United States)

Song, Hyohak; Huh, Yun Suk; Lee, Sang Yup; Hong, Won Hi; Hong, Yeon Ki

2007-12-01

There have recently been much advances in the production of succinic acid, an important four-carbon dicarboxylic acid for many industrial applications, by fermentation of several natural and engineered bacterial strains. Mannheimia succiniciproducens MBEL55E isolated from bovine rumen is able to produce succinic acid with high efficiency, but also produces acetic, formic and lactic acids just like other anaerobic succinic acid producers. We recently reported the development of an engineered M. succiniciproducens LPK7 strain which produces succinic acid as a major fermentation product while producing much reduced by-products. Having an improved succinic acid producer developed, it is equally important to develop a cost-effective downstream process for the recovery of succinic acid. In this paper, we report the development of a simpler and more efficient method for the recovery of succinic acid. For the recovery of succinic acid from the fermentation broth of LPK7 strain, a simple process composed of a single reactive extraction, vacuum distillation, and crystallization yielded highly purified succinic acid (greater than 99.5% purity, wt%) with a high yield of 67.05wt%. When the same recovery process or even multiple reactive extraction steps were applied to the fermentation broth of MBEL55E, lower purity and yield of succinic acid were obtained. These results suggest that succinic acid can be purified in a cost-effective manner by using the fermentation broth of engineered LPK7 strain, showing the importance of integrating the strain development, fermentation and downstream process for optimizing the whole processes for succinic acid production.

Short communication: Conservation of Streptococcus uberis adhesion molecule and the sua gene in strains of Streptococcus uberis isolated from geographically diverse areas.

Science.gov (United States)

Yuan, Ying; Dego, Oudessa Kerro; Chen, Xueyan; Abadin, Eurife; Chan, Shangfeng; Jory, Lauren; Kovacevic, Steven; Almeida, Raul A; Oliver, Stephen P

2014-12-01

The objective was to identify and sequence the sua gene (GenBank no. DQ232760; http://www.ncbi.nlm.nih.gov/genbank/) and detect Streptococcus uberis adhesion molecule (SUAM) expression by Western blot using serum from naturally S. uberis-infected cows in strains of S. uberis isolated in milk from cows with mastitis from geographically diverse areas of the world. All strains evaluated yielded a 4.4-kb sua-containing PCR fragment that was subsequently sequenced. Deduced SUAM AA sequences from those S. uberis strains evaluated shared >97% identity. The pepSUAM sequence located at the N terminus of SUAM was >99% identical among strains of S. uberis. Streptococcus uberis adhesion molecule expression was detected in all strains of S. uberis tested. These results suggest that sua is ubiquitous among strains of S. uberis isolated from diverse geographic locations and that SUAM is immunogenic. Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

[GM1-dot-EIA for the detection of toxin-producing Vibrio cholerae strains].

Science.gov (United States)

Markina, O V; Alekseeva, L P; Telesmanich, N R; Chemisova, O S; Akulova, M V; Markin, N V

2011-05-01

A new variant of enzyme immunoassay (EIA) has been developed on the basis of GM1 gangliosides to detect the toxin-producing Vibrio cholerae strains--GM1-dot-EIA. Experiments were run using a nitrocellulose membrane to bind GM1 gangliosides and polyclonal antitoxic serum to detect cholerogen. GM1-dot-EIA testing identified cholera toxin in 11 of 13 supernatants of V. cholerae eltor ctx(+) strains isolated from man and in 3 of 7 supernatants of V. cholerae eltor ctx(+) strains isolated from water. These data agree with those obtained in CM1-EIA. There was no reaction with the supernatants of other microorganisms. The sensitivity of the technique was 10 ng/ml. Thus, the simple and specific GM1-dot-EIA may be recommended to detect toxin-producing V cholerae strains isolated from man and water.

CHARACTERIZATION OF EXTENDED-SPECTRUM Β-LACTAMASE-PRODUCING ESCHERICHIA COLI STRAINS ISOLATED FROM DAIRY PRODUCTS

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Rahem Khoshbakht

2014-02-01

Full Text Available Extended-spectrum β-lactamases (ESBLs are enzymes that hydrolyze the β-lactam ring, and ESBL-producing E. coli has rapidly spread worldwide with pose a serious hazard for humans. The aim of this study was to determine the prevalence of ESBL producing E. coli and molecular evaluation of four ESBL-associated genes among E. coli strains isolated from milk and cheese in southern Iran. Antibiotic susceptibility test was carried out for a total of 150 isolates of E. coli, previously collected from dairy products. ESBL production was screened using a double-disc synergy test (DDST and presence of four ESBL genes (PER, VEB, TEM and CTX-M was tested using PCR. Among 150 E. coli strains 57 (38% isolates were identified as ESBL-producing strains. All ESBL positive isolates could be typed for one or more genes and the most prevalent ESBL-associated gene was CTX-M (80.7%. The PER gene was not present among isolates. Isolates showed high susceptibility to imipe¬nem and cefoxitin. The results showed the high prevalence of ESBL producing E. coli strains among dairy products and high occurrence of CTX-M-associated ESBL activity among isolates indicating the hazards of increasing the strains with antibiotic resistance which can transfer to human trough the dairy food products.

Characterization of new exopolysaccharides produced by coculturing of L. kefiranofaciens with yoghurt strains.

Science.gov (United States)

Ahmed, Zaheer; Wang, Yanping; Anjum, Nomana; Ahmad, Hajra; Ahmad, Asif; Raza, Mohsin

2013-08-01

This project was designed to study the coculturing affect of exopolysaccharide (EPS) producing strains Lactobacillus kefiranofaciens (L.k) ZW3, with non EPS producing strains L. bulgaricus (L.b) and Streptococcus thermophilus (S.t) in three different combinations: L.k+L.b, L.k+S.t, and L.k+L.b+S.t. FTIR analysis revealed presence of strong stretch in regions of 3400, 2900 and 1647cm(-1) which is characteristic of a typical polysaccharide. Co-cultured EPSs were composed of glucose, galactose, arabinose and xylose; and their sugar compositions were different from ZW3 polysaccharide that was mainly composed of gluco-galactan. Peak temperature for L.k+L.b, L.k+S.t, L.k+S.t+L.b and ZW3 polymers were 90.59, 87.61, 95.18 and 97.38°C, respectively. Thermal analysis revealed degradation temperature of 326.44, 294.6, 296.7 and 299.62°C for L.k+L.b, L.k+S.t, L.k+S.t+L.b and ZW3 polymers, respectively. SEM and AFM analysis divulged that three cocultured EPSs had different surface morphology than ZW3 polymer. Since co-cultured polymers have different structure than the polymer produced exclusively by EPS producing strain, it can be safely concluded from the study that co-culturing can be one way to change the structure of polymers. Coculturing of L. kefiranofaciens with non-EPS producing strains resulted in yoghurt with increased viscosity and delayed syneresis. Copyright © 2013 Elsevier B.V. All rights reserved.

Safety Evaluation of Enterocin Producer Enterococcus sp. Strains Isolated from Traditional Turkish Cheeses.

Science.gov (United States)

Avcı, Mine; Özden Tuncer, Banu

2017-07-06

The purpose of this study was to determine the antimicrobial activity and occurrence of bacteriocin structural genes in Enterococcus spp. isolated from different cheeses and also investigate some of their virulence factors. Enterococcus strains were isolated from 33 different cheeses. Enterococcus faecium (6 strains) and Enterococcus faecalis (5 strains) enterocin-producing strains were identified by 16S rDNA analyses. Structural genes entA, entB, entP and entX were detected in some isolates. Multiple enterocin structural genes were found in 7 strains. None of the tested enterococci demonstrated anyβ-haemolytic activity and only one strain had gelatinase activity. Six strains showed multiple antibiotic resistance patterns and in addition, vanA and several virulence genes were detected in many strains. Only E. faecalis MBE1-9 showed tyrosine decarboxylase activity and tdc gene was detected only in this strain.

Draft Genome Sequence of Hoeflea sp. Strain BAL378, a Potential Producer of Bioactive Compounds

DEFF Research Database (Denmark)

Bentzon-Tilia, Mikkel; Riemann, Lasse; Gram, Lone

2014-01-01

Some phytoplankton-associated marine bacteria produce bioactive compounds. Members of the genus Hoeflea may be examples of such bacteria; however, data describing their metabolisms are scarce. Here, we report the draft genome sequence of Hoeflea sp. strain BAL378, a putative producer of bacterioc......Some phytoplankton-associated marine bacteria produce bioactive compounds. Members of the genus Hoeflea may be examples of such bacteria; however, data describing their metabolisms are scarce. Here, we report the draft genome sequence of Hoeflea sp. strain BAL378, a putative producer...

Strain diversity of CTX-M-producing Enterobacteriaceae in individual pigs

DEFF Research Database (Denmark)

Hansen, Katrine Hartung; Bortolaia, Valeria; Damborg, Peter Panduro

2014-01-01

of CTX-M-2/97-producing Proteus mirabilis or Providencia rettgeri was observed in two sows and two offspring. At least two genetically unrelated CTX-M-producing E. coli strains were isolated from approximately one fourth of the samples with remarkable differences between isolates obtained by enrichment...

Screening on the high yield validamycin producing strain by implantation with N+ and Ti+ ion source

International Nuclear Information System (INIS)

Yu Long; An Xiao

2007-01-01

In order to compared the mutagenic effects of the validamycin producing the strain (Streptomyces hygroscopicus var. Jingganggensis Yen.) was implanted with two kinds of ion sources. The results showed that when two kinds of ion sources implanted into the strain by turns, more positive mutants and higher yield would be acquired. Using this method, a high-yielding strain B1-3 was obtained, which produce the titer of validamycin A of 21514, and was 54.4% higher than that of the original strain. (authors)

In silico screening for candidate chassis strains of free fatty acid-producing cyanobacteria.

Science.gov (United States)

Motwalli, Olaa; Essack, Magbubah; Jankovic, Boris R; Ji, Boyang; Liu, Xinyao; Ansari, Hifzur Rahman; Hoehndorf, Robert; Gao, Xin; Arold, Stefan T; Mineta, Katsuhiko; Archer, John A C; Gojobori, Takashi; Mijakovic, Ivan; Bajic, Vladimir B

2017-01-05

Finding a source from which high-energy-density biofuels can be derived at an industrial scale has become an urgent challenge for renewable energy production. Some microorganisms can produce free fatty acids (FFA) as precursors towards such high-energy-density biofuels. In particular, photosynthetic cyanobacteria are capable of directly converting carbon dioxide into FFA. However, current engineered strains need several rounds of engineering to reach the level of production of FFA to be commercially viable; thus new chassis strains that require less engineering are needed. Although more than 120 cyanobacterial genomes are sequenced, the natural potential of these strains for FFA production and excretion has not been systematically estimated. Here we present the FFA SC (FFASC), an in silico screening method that evaluates the potential for FFA production and excretion of cyanobacterial strains based on their proteomes. A literature search allowed for the compilation of 64 proteins, most of which influence FFA production and a few of which affect FFA excretion. The proteins are classified into 49 orthologous groups (OGs) that helped create rules used in the scoring/ranking of algorithms developed to estimate the potential for FFA production and excretion of an organism. Among 125 cyanobacterial strains, FFASC identified 20 candidate chassis strains that rank in their FFA producing and excreting potential above the specifically engineered reference strain, Synechococcus sp. PCC 7002. We further show that the top ranked cyanobacterial strains are unicellular and primarily include Prochlorococcus (order Prochlorales) and marine Synechococcus (order Chroococcales) that cluster phylogenetically. Moreover, two principal categories of enzymes were shown to influence FFA production the most: those ensuring precursor availability for the biosynthesis of lipids, and those involved in handling the oxidative stress associated to FFA synthesis. To our knowledge FFASC is the first

In silico screening for candidate chassis strains of free fatty acid-producing cyanobacteria

KAUST Repository

Motwalli, Olaa Amin

2017-01-05

Background Finding a source from which high-energy-density biofuels can be derived at an industrial scale has become an urgent challenge for renewable energy production. Some microorganisms can produce free fatty acids (FFA) as precursors towards such high-energy-density biofuels. In particular, photosynthetic cyanobacteria are capable of directly converting carbon dioxide into FFA. However, current engineered strains need several rounds of engineering to reach the level of production of FFA to be commercially viable; thus new chassis strains that require less engineering are needed. Although more than 120 cyanobacterial genomes are sequenced, the natural potential of these strains for FFA production and excretion has not been systematically estimated. Results Here we present the FFA SC (FFASC), an in silico screening method that evaluates the potential for FFA production and excretion of cyanobacterial strains based on their proteomes. A literature search allowed for the compilation of 64 proteins, most of which influence FFA production and a few of which affect FFA excretion. The proteins are classified into 49 orthologous groups (OGs) that helped create rules used in the scoring/ranking of algorithms developed to estimate the potential for FFA production and excretion of an organism. Among 125 cyanobacterial strains, FFASC identified 20 candidate chassis strains that rank in their FFA producing and excreting potential above the specifically engineered reference strain, Synechococcus sp. PCC 7002. We further show that the top ranked cyanobacterial strains are unicellular and primarily include Prochlorococcus (order Prochlorales) and marine Synechococcus (order Chroococcales) that cluster phylogenetically. Moreover, two principal categories of enzymes were shown to influence FFA production the most: those ensuring precursor availability for the biosynthesis of lipids, and those involved in handling the oxidative stress associated to FFA synthesis. Conclusion To

Inhibition of food-related bacteria by antibacterial substances produced by Pseudomonas sp. strains isolated from pasteurized milk

Directory of Open Access Journals (Sweden)

Ana Beatriz Ferreira Rangel

2013-12-01

Full Text Available In this work, the production of antimicrobial substances by strains of Pseudomonas sp. isolated from pasteurized milk and their potential action against food-related bacteria were investigated. Samples of pasteurized milk were purchased from arbitrarily chosen commercial establishments in the city of Rio de Janeiro, Brazil. Of the four samples analyzed, three presented several typical colonies of Pseudomonas. About 100 colonies were chosen and subjected to biochemical tests for confirmation of their identity. Eighteen strains of the Pseudomonas genus were identified and submitted to tests for the production of antimicrobial substances. Twelve strains (66.7% were identified as Pseudomonas fluorescens, four (22.2% as P. aeruginosa, one (5.5% as P. mendocina and one (5.5% as P. pseudoalcaligenes. Only two P. fluorescens strains were unable to produce any antimicrobial substance against any of the indicator strains tested. Most of the strains presented a broad spectrum of action, inhibiting reference and food-related strains such as Proteus vulgaris, Proteus mirabilis, Hafnia alvei, Yersinia enterocolitica, Escherichia coli and Salmonella typhi. Five antimicrobial substance-producing strains, which presented the broadest spectrum of action, were also tested against Staphylococcus aureus reference strains and 26 Staphylococcus sp. strains isolated from foods, some of which were resistant to antibiotics. The producer strains 8.1 and 8.3, both P. aeruginosa, were able to inhibit all the staphylococcal strains tested. The antimicrobial substances produced by strains 8.1 and 8.3 did not seem to be typical bacteriocins, since they were resistant to the three proteolytic enzymes tested. Experiments involving the characterization of these substances are being carried out in order to evaluate their biotechnological application.

Use of pantothenate as a metabolic switch increases the genetic stability of farnesene producing Saccharomyces cerevisiae.

Science.gov (United States)

Sandoval, Celeste M; Ayson, Marites; Moss, Nathan; Lieu, Bonny; Jackson, Peter; Gaucher, Sara P; Horning, Tizita; Dahl, Robert H; Denery, Judith R; Abbott, Derek A; Meadows, Adam L

2014-09-01

We observed that removing pantothenate (vitamin B5), a precursor to co-enzyme A, from the growth medium of Saccharomyces cerevisiae engineered to produce β-farnesene reduced the strain׳s farnesene flux by 70%, but increased its viability, growth rate and biomass yield. Conversely, the growth rate and biomass yield of wild-type yeast were reduced. Cultivation in media lacking pantothenate eliminates the growth advantage of low-producing mutants, leading to improved production upon scale-up to lab-scale bioreactor testing. An omics investigation revealed that when exogenous pantothenate levels are limited, acyl-CoA metabolites decrease, β-oxidation decreases from unexpectedly high levels in the farnesene producer, and sterol and fatty acid synthesis likely limits the growth rate of the wild-type strain. Thus pantothenate supplementation can be utilized as a "metabolic switch" for tuning the synthesis rates of molecules relying on CoA intermediates and aid the economic scale-up of strains producing acyl-CoA derived molecules to manufacturing facilities. Copyright © 2014 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

Molecular Detection of Aflatoxin Producing Strains of Aspergillus Flavus from Peanut (Arachis Hypogaea

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Adeela Hussain

2015-02-01

Full Text Available Aflatoxins are the potential carcinogens produced as secondary metabolites by Aspergillus flavus. They have the ability to contaminate large number of food which ultimately affect the human population. Malt extract agar was selected for the growth of control stains of fungus. The aim of the study was to develop a reliable and quick method for the detection of aflatoxin producing strains in peanuts by using molecular approaches. Total 80 samples of infected peanuts were collected from four different cities of Punjab and checked for their aflatoxin contamination. For aflatoxin detection, three target genes nor1, ver1 and aflR were selected which was involved in the aflatoxin biosynthesis. In all examined cases, 24 out of 80 (30% samples successfully amplified all three genes indicating aflatoxigenic activity. Discrimination between aflatoxigenic and non-aflatoxigenic strains were also determined on the basis of amplification of these three target DNA fragments. In this study, it was also demonstrated that only specific strains were able to produce the aflatoxin contamination in peanuts.

Quorum sensing molecules production by nosocomial and soil isolates Acinetobacter baumannii.

Science.gov (United States)

Erdönmez, Demet; Rad, Abbas Yousefi; Aksöz, Nilüfer

2017-12-01

Acinetobacter species remain alive in hospitals on various surfaces, both dry and moist, forming an important source of hospital infections. These bacteria are naturally resistant to many antibiotic classes. Although the role of the quorum sensing system in regulating the virulence factors of Acinetobacter species has not been fully elucidated, it has been reported that they play a role in bacterial biofilm formation. The biofilm formation helps them to survive under unfavorable growth conditions and antimicrobial treatments. It is based on the accumulation of bacterial communication signal molecules in the area. In this study, we compared the bacterial signal molecules of 50 nosocomial Acinetobacter baumannii strain and 20 A. baumannii strain isolated from soil. The signal molecules were detected by the biosensor bacteria (Chromobacterium violaceum 026, Agrobacterium tumefaciens A136, and Agrobacterium tumefaciens NTL1) and their separation was determined by thin-layer chromatography. As a result, it has been found that soil-borne isolates can produce 3-oxo-C8-AHL and C8-AHL, whereas nosocomial-derived isolates can produce long-chain signals such as C10-AHL, C12-AHL, C14-AHL and C16-AHL. According to these results, it is possible to understand that these signal molecules are found in the infection caused by A. baumannii. The inhibition of this signaling molecules in a communication could use to prevent multiple antibiotic resistance of these bacteria.

In vitro evaluation of immunological properties of extracellular polysaccharides produced by Lactobacillus delbrueckii strains.

Science.gov (United States)

Kishimoto, Mana; Nomoto, Ryohei; Osawa, Ro

2015-01-01

We investigated the variation in immunological properties of the extracellular polysaccharides (EPSs) produced by different Lactobacillus delbrueckii strains as well as that of their monosaccharide composition. The monosaccharide composition of each EPS produced by L. delbrueckii strains, as determined by thin layer chromatography (TLC), showed an appreciable variation in a strain-dependent manner, which could be broadly assigned to 4 TLC groups. Meanwhile, the immunological properties of the EPSs produced by 10 L. delbrueckii strains were evaluated in a semi-intestinal model using a Transwell co-culture system, which employed human intestinal epithelial Caco-2 cells on the apical side and murine macrophage RAW264.7 cells on the basolateral side. Each EPS was added to the apical side to allow direct contact with Caco-2 cells and incubated for 6 hr. After incubation, the amounts of TNF-α and several cytokines that had been released by either RAW264.7 or Caco-2 cells were then quantified by cytotoxic activity on L929 cells or the RT-PCR method. It was found that the EPS-stimulated RAW264.7 cells express different profiles of cytokine production via Caco-2 cells but that the profile difference could not be related to the above TLC grouping. The evidence suggests that the EPSs of L. delbrueckii strains are diverse not only in their biochemical structure but also in their immunological properties.

Isolation of Biosurfactant Producing Bacteria from Oil Reservoirs

OpenAIRE

A Tabatabaee, M Mazaheri Assadi, AA Noohi,VA Sajadian

2005-01-01

Biosurfactants or surface-active compounds are produced by microoaganisms. These molecules reduce surface tension both aqueous solutions and hydrocarbon mixtures. In this study, isolation and identification of biosurfactant producing bacteria were assessed. The potential application of these bacteria in petroleum industry was investigated. Samples (crude oil) were collected from oil wells and 45 strains were isolated. To confirm the ability of isolates in biosurfactant production, haemolysis ...

CHARACTERIZATION OF A NEW BACILLUS-STEAROTHERMOPHILUS ISOLATE - A HIGHLY THERMOSTABLE ALPHA-AMYLASE-PRODUCING STRAIN

NARCIS (Netherlands)

WIND, RD; BUITELAAR, RM; EGGINK, G; HUIZING, HJ; DIJKHUIZEN, L

A novel strain of Bacillus stearothermophilus was isolated from samples of a potato-processing industry. Compared to known alpha-amylases from other B. stearothermophilus strains, the isolate was found to produce a highly thermostable alpha-amylase. The half-time of inactivation of this

Isolation of Biosurfactant Producing Bacteria from Oil Reservoirs

Directory of Open Access Journals (Sweden)

A Tabatabaee, M Mazaheri Assadi, AA Noohi,VA Sajadian

2005-01-01

Full Text Available Biosurfactants or surface-active compounds are produced by microoaganisms. These molecules reduce surface tension both aqueous solutions and hydrocarbon mixtures. In this study, isolation and identification of biosurfactant producing bacteria were assessed. The potential application of these bacteria in petroleum industry was investigated. Samples (crude oil were collected from oil wells and 45 strains were isolated. To confirm the ability of isolates in biosurfactant production, haemolysis test, emulsification test and measurement of surface tension were conducted. We also evaluated the effect of different pH, salinity concentrations, and temperatures on biosurfactant production. Among importance features of the isolated strains, one of the strains (NO.4: Bacillus.sp showed high salt tolerance and their successful production of biosurfactant in a vast pH and temperature domain and reduced surface tension to value below 40 mN/m. This strain is potential candidate for microbial enhanced oil recovery. The strain4 biosurfactant component was mainly glycolipid in nature.

Morphological characterization of recombinant strains of Aspergillus oryzae producing alpha-amylase during batch cultivations

DEFF Research Database (Denmark)

Spohr, Anders Bendsen; Carlsen, Morten; Nielsen, Jens Bredal

1997-01-01

Three alpha-amylase producing strains of Aspergillus oryzae used for recombinant protein production have been studied with respect to growth and protein production. By comparing the three strains with respect to morphology and protein production it is shown that a morphological mutant with a more...

Design of homo-organic acid producing strains using multi-objective optimization

DEFF Research Database (Denmark)

Kim, Tae Yong; Park, Jong Myoung; Kim, Hyun Uk

2015-01-01

Production of homo-organic acids without byproducts is an important challenge in bioprocess engineering to minimize operation cost for separation processes. In this study, we used multi-objective optimization to design Escherichia coli strains with the goals of maximally producing target organic ...

Isolation and Identification of L-asparaginase producing Erwinia strains which isolated from Potato Farms

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Arastoo Badoei-Dalfard

2016-09-01

Full Text Available Introduction: L-Asparaginase can be effectively used for the treatment of lymphoblastic leukemia. The rapid growth of cancer cells are needed for L-asparagine abundant storage. L-asparaginase catalyzes the hydrolysis of L-asparagine into L-aspartic acid and ammonia. The purpose of this study was to isolate and identify the L-asparaginase producing Erwinia strains from the potato farms of Jiroft. Materials and methods: Pectolytic Erwinia species isolated from crumbling potato in M9 medium. The desired L-asparaginase producing bacteria were isolated based on the color changes. Biochemical-microbial and the plant pathogenicity tests of these strains were also investigated with potato and geranium. The L-asparaginase production and molecular detection of these Erwinia strains were also investigated. Results: In this study, L-asparaginase producing Erwinia was isolated on the CVP and M9 mediums. The inoculation of Erwinia strains on the potato and geranium plants showed that Er8 and Er11 species have the ability to cause plant pathogenicity. Results showed that the maximum pathogenicity of Er8 and Er11 was observed after 48 and 15 h of inoculation in potato and geranium plants, respectively. 16S rDNA sequencing and phylogenetic analyses exhibited that Er8 and Er11 strains were similar to Erwinia chrysanthemi with 98% homology. Discussion and conclusion: Because of several applications of the Erwinia L-asparaginase in various fields, isolated Erwinia and their L-asparaginase can be suitable for applied utilization.

Metabolic engineering of a haploid strain derived from a triploid industrial yeast for producing cellulosic ethanol.

Science.gov (United States)

Kim, Soo Rin; Skerker, Jeffrey M; Kong, In Iok; Kim, Heejin; Maurer, Matthew J; Zhang, Guo-Chang; Peng, Dairong; Wei, Na; Arkin, Adam P; Jin, Yong-Su

2017-03-01

Many desired phenotypes for producing cellulosic biofuels are often observed in industrial Saccharomyces cerevisiae strains. However, many industrial yeast strains are polyploid and have low spore viability, making it difficult to use these strains for metabolic engineering applications. We selected the polyploid industrial strain S. cerevisiae ATCC 4124 exhibiting rapid glucose fermentation capability, high ethanol productivity, strong heat and inhibitor tolerance in order to construct an optimal yeast strain for producing cellulosic ethanol. Here, we focused on developing a general approach and high-throughput screening method to isolate stable haploid segregants derived from a polyploid parent, such as triploid ATCC 4124 with a poor spore viability. Specifically, we deleted the HO genes, performed random sporulation, and screened the resulting segregants based on growth rate, mating type, and ploidy. Only one stable haploid derivative (4124-S60) was isolated, while 14 other segregants with a stable mating type were aneuploid. The 4124-S60 strain inherited only a subset of desirable traits present in the parent strain, same as other aneuploids, suggesting that glucose fermentation and specific ethanol productivity are likely to be genetically complex traits and/or they might depend on ploidy. Nonetheless, the 4124-60 strain did inherit the ability to tolerate fermentation inhibitors. When additional genetic perturbations known to improve xylose fermentation were introduced into the 4124-60 strain, the resulting engineered strain (IIK1) was able to ferment a Miscanthus hydrolysate better than a previously engineered laboratory strain (SR8), built by making the same genetic changes. However, the IIK1 strain showed higher glycerol and xylitol yields than the SR8 strain. In order to decrease glycerol and xylitol production, an NADH-dependent acetate reduction pathway was introduced into the IIK1 strain. By consuming 2.4g/L of acetate, the resulting strain (IIK1A

Effects of some organic pollutants on the exopolysaccharides (EPSs) produced by some Pseudomonas spp. strains

International Nuclear Information System (INIS)

Onbasli, Dilsad; Aslim, Belma

2009-01-01

In this study, isolation and characterization of exopolysaccharides produced by Pseudomonas aeruginosa B1, P. fluorescens B5, P. stutzeri B11 and P. putida B15 which had been seen to produce exopolymers of potential interest in biotechnological applications were examined. To initiate the observation of the organic pollutants-polymer interactions, the yield and properties of their extracellular polysaccharide were researched. The exopolysaccharide production by these strains during growth in nutrient broth medium (control) was 41-75 mg L -1 . Also, P. aeruginosa B1, P. fluorescens B5, P. stutzeri B11 and P. putida B15 had exhibited high production of EPSs in presence of various organic pollutants (2,4-D, benzene, BTX and gasoline, respectively) in mineral salt medium (MSM) as a sole carbon source. EPS production by the 4 strains ranged from 40 mg L -1 to 8 mg L -1 . Monosaccharide composition of EPS produced by these cultures were analyzed by HPLC. Results indicated that EPSs of strains contained neutral sugars and acetylated amino sugars. The neutral sugars in the EPS were mainly composed of glucose, arabinose, glycerol, ribose. The presence of galactronic acid, N-acetyl-D-galactosamin and N-acetyl-D-glucosamine indicated the acidic nature of the polysaccharide. Glycerol was the basic structural unit of EPS produced by the strains except P. stutzeri B11 (MSM with 1% BTX). Strain B1 (in NB medium) was found to be composed of neutral sugars (100%) while strain B1 [in MSM medium with 0.2% (v/v) 2.4-D] contained neutral sugars (70.0%), acetylated amino sugars (30.0%). Also, EPS content of strain B5 (in the NB medium) was neutral sugars (99.8%), acetylated amino sugars (0.2%) while the strain B5 [in MSM medium containing the 1% (v/v) benzene] was found to contain neutral sugars (99.9%), acetylated amino sugars (0.1%). However, EPS monomer composition by strain B11 was detected as neutral sugars (99.77%), acetylated amino sugars (0.23%) in NB medium while the strain B11

Proteome response of Tribolium castaneum larvae to Bacillus thuringiensis toxin producing strains.

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Estefanía Contreras

Full Text Available Susceptibility of Tribolium castaneum (Tc larvae was determined against spore-crystal mixtures of five coleopteran specific and one lepidopteran specific Bacillus thuringiensis Cry toxin producing strains and those containing the structurally unrelated Cry3Ba and Cry23Aa/Cry37Aa proteins were found toxic (LC(50 values 13.53 and 6.30 µg spore-crystal mixture/µL flour disc, respectively. Using iTRAQ combined with LC-MS/MS allowed the discovery of seven novel differentially expressed proteins in early response of Tc larvae to the two active spore-crystal mixtures. Proteins showing a statistically significant change in treated larvae compared to non-intoxicated larvae fell into two major categories; up-regulated proteins were involved in host defense (odorant binding protein C12, apolipophorin-III and chemosensory protein 18 and down-regulated proteins were linked to metabolic pathways affecting larval metabolism and development (pyruvate dehydrogenase Eα subunit, cuticular protein, ribosomal protein L13a and apolipoprotein LI-II. Among increased proteins, Odorant binding protein C12 showed the highest change, 4-fold increase in both toxin treatments. The protein displayed amino acid sequence and structural homology to Tenebrio molitor 12 kDa hemolymph protein b precursor, a non-olfactory odorant binding protein. Analysis of mRNA expression and mortality assays in Odorant binding protein C12 silenced larvae were consistent with a general immune defense function of non-olfactory odorant binding proteins. Regarding down-regulated proteins, at the transcriptional level, pyruvate dehydrogenase and cuticular genes were decreased in Tc larvae exposed to the Cry3Ba producing strain compared to the Cry23Aa/Cry37Aa producing strain, which may contribute to the developmental arrest that we observed with larvae fed the Cry3Ba producing strain. Results demonstrated a distinct host transcriptional regulation depending upon the Cry toxin treatment. Knowledge

Draft Genome Sequence of the Efficient Bioflocculant-Producing Bacterium Paenibacillus sp. Strain A9

Science.gov (United States)

Liu, Jin-liang; Hu, Xiao-min

2013-01-01

Paenibacillus sp. strain A9 is an important bioflocculant-producing bacterium, isolated from a soil sample, and is pale pink-pigmented, aerobic, and Gram-positive. Here, we report the draft genome sequence and the initial findings from a preliminary analysis of strain A9, which is a novel species of Paenibacillus. PMID:23618713

Nonbioluminescent strains of Photobacterium phosphoreum produce the cell-to-cell communication signal N-(3-Hydroxyoctanoyl)homoserine lactone

DEFF Research Database (Denmark)

Flodgaard, Lars; Dalgaard, Paw; Andersen, Jens Bo

2005-01-01

Bioluminescence is a common phenotype in marine bacteria, such As Vibrio and Photobacterium species, and can be quorum regulated by N-acylated homoserine lactones (AHLs). We extracted a molecule that induced a bacterial AHL monitor (Agrobacterium tumefaciens NT1 [pZLR4]) from packed cod fillets......) and shape to N-(3-hydroxyoctanoyl)homoserine lactone, and the presence of this molecule in culture supernatants from a nonbioluminescent strain of P. phosphoreum was confirmed by high-performance liquid chromatography-positive electrospray high-resolution mass spectrometry. Bioluminescence (in a non...

Nesterenkonia sp. strain F, a halophilic bacterium producing acetone, butanol, and ethanol under aerobic conditions.

Science.gov (United States)

Amiri, Hamid; Azarbaijani, Reza; Parsa Yeganeh, Laleh; Shahzadeh Fazeli, Abolhassan; Tabatabaei, Meisam; Salekdeh, Ghasem Hosseini; Karimi, Keikhosro

2016-01-04

The moderately halophilic bacterium Nesterenkonia sp. strain F, which was isolated from Aran-Bidgol Lake (Iran), has the ability to produce acetone, butanol, and ethanol (ABE) as well as acetic and butyric acids under aerobic and anaerobic conditions. This result is the first report of ABE production with a wild microorganism from a family other than Clostridia and also the first halophilic species shown to produce butanol under aerobic cultivation. The cultivation of Nesterenkonia sp. strain F under anaerobic conditions with 50 g/l of glucose for 72 h resulted in the production of 105 mg/l of butanol, 122 mg/l of acetone, 0.2 g/l of acetic acid, and 2.5 g/l of butyric acid. Furthermore, the strain was cultivated on media with different glucose concentrations (20, 50, and 80 g/l) under aerobic and anaerobic conditions. Through fermentation with a 50 g/l initial glucose concentration under aerobic conditions, 66 mg/l of butanol, 125 mg/l of acetone, 291 mg/l of ethanol, 5.9 g/l of acetic acid, and 1.2 g/l of butyric acid were produced. The enzymes pertaining to the fermentation pathway in the strain were compared with the enzymes of Clostridium spp., and the metabolic pathway of fermentation used by Nesterenkonia sp. strain F was investigated.

Clonality and Resistome analysis of KPC-producing Klebsiella pneumoniae strain isolated in Korea using whole genome sequencing.

Science.gov (United States)

Lee, Yangsoon; Kim, Bong-Soo; Chun, Jongsik; Yong, Ji Hyun; Lee, Yeong Seon; Yoo, Jung Sik; Yong, Dongeun; Hong, Seong Geun; D'Souza, Roshan; Thomson, Kenneth S; Lee, Kyungwon; Chong, Yunsop

2014-01-01

We analyzed the whole genome sequence and resistome of the outbreak Klebsiella pneumoniae strain MP14 and compared it with those of K. pneumoniae carbapenemase- (KPC-) producing isolates that showed high similarity in the NCBI genome database. A KPC-2-producing multidrug-resistant (MDR) K. pneumoniae clinical isolate was obtained from a patient admitted to a Korean hospital in 2011. The strain MP14 was resistant to all tested β-lactams including monobactam, amikacin, levofloxacin, and cotrimoxazole, but susceptible to tigecycline and colistin. Resistome analysis showed the presence of β-lactamase genes including bla KPC-2, bla SHV-11, bla TEM-169, and bla OXA-9. MP14 also possessed aac(6'-)Ib, aadA2, and aph(3'-)Ia as aminoglycoside resistance-encoding genes, mph(A) for macrolides, oqxA and oqxB for quinolone, catA1 for phenicol, sul1 for sulfonamide, and dfrA12 for trimethoprim. Both SNP tree and cgMLST analysis showed the close relatedness with the KPC producers (KPNIH strains) isolated from an outbreak in the USA and colistin-resistant strains isolated in Italy. The plasmid-scaffold genes in plasmids pKpQil, pKpQil-IT, pKPN3, or pKPN-IT were identified in MP14, KPNIH, and Italian strains. The KPC-2-producing MDR K. pneumoniae ST258 stain isolated in Korea was highly clonally related with MDR K. pneumoniae strains from the USA and Italy. Global spread of KPC-producing K. pneumoniae is a worrying phenomenon.

Clonality and Resistome Analysis of KPC-Producing Klebsiella pneumoniae Strain Isolated in Korea Using Whole Genome Sequencing

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Yangsoon Lee

2014-01-01

Full Text Available We analyzed the whole genome sequence and resistome of the outbreak Klebsiella pneumoniae strain MP14 and compared it with those of K. pneumoniae carbapenemase- (KPC- producing isolates that showed high similarity in the NCBI genome database. A KPC-2-producing multidrug-resistant (MDR K. pneumoniae clinical isolate was obtained from a patient admitted to a Korean hospital in 2011. The strain MP14 was resistant to all tested β-lactams including monobactam, amikacin, levofloxacin, and cotrimoxazole, but susceptible to tigecycline and colistin. Resistome analysis showed the presence of β-lactamase genes including blaKPC-2, blaSHV-11, blaTEM-169, and blaOXA-9. MP14 also possessed aac(6′-Ib, aadA2, and aph(3′-Ia as aminoglycoside resistance-encoding genes, mph(A for macrolides, oqxA and oqxB for quinolone, catA1 for phenicol, sul1 for sulfonamide, and dfrA12 for trimethoprim. Both SNP tree and cgMLST analysis showed the close relatedness with the KPC producers (KPNIH strains isolated from an outbreak in the USA and colistin-resistant strains isolated in Italy. The plasmid-scaffold genes in plasmids pKpQil, pKpQil-IT, pKPN3, or pKPN-IT were identified in MP14, KPNIH, and Italian strains. The KPC-2-producing MDR K. pneumoniae ST258 stain isolated in Korea was highly clonally related with MDR K. pneumoniae strains from the USA and Italy. Global spread of KPC-producing K. pneumoniae is a worrying phenomenon.

Detection and transmission of extracellular fac-tor producing Streptococcus suis serotype 2 strains in pigs

NARCIS (Netherlands)

Swildens, B.

2009-01-01

DETECTION AND TRANSMISSION OF EXTRACELLULAR FACTOR PRODUCING STREPTOCOCCUS SUIS SEROTYPE 2 STRAINS IN PIGS INTRODUCTION Streptococcus suis (S.suis) has been implicated in the etiology of many diseases among which meningitis in pigs. The virulent extracellular factor-positive strains of S.suis

Lactobacillus plantarum CIDCA 8327: An α-glucan producing-strain isolated from kefir grains.

Science.gov (United States)

Gangoiti, M V; Puertas, A I; Hamet, M F; Peruzzo, P J; Llamas, M G; Medrano, M; Prieto, A; Dueñas, M T; Abraham, A G

2017-08-15

Lactobacillus plantarum CIDCA 8327 is an exopolysaccharide (EPS)-producer strain isolated from kefir with promising properties for the development of functional foods. The aim of the present study was to characterize the structure of the EPS synthesized by this strain grown in skim milk or semidefined medium (SDM). Additionally, genes involved in EPS synthesis were detected by PCR. L. plantarum produces an EPS with a molecular weight of 10 4 Da in both media. When grown in SDM produce an heteropolysaccharide composed mainly of glucose, glucosamine and rhamnose meanwhile the EPS produced in milk was composed exclusively of glucose indicating the influence of the sugar source. FTIR spectra of this EPS showed signals attributable to an α-glucan. Both by 1 H NMR and methylation analysis it was possible to determine that this polysaccharide is a branched α-(1→4)-d-glucan composed of 80% linear α-(1→4)-d-glucopyranosyl units and 19% (1→4)-d-glucopyranosyl units substituted at O-3 by single α-d-glucopyranosil residues. Copyright © 2017 Elsevier Ltd. All rights reserved.

The prevalence of ESBL-producing E-coli and Klebsiella strains in the Copenhagen area of Denmark

DEFF Research Database (Denmark)

Kjerulf, A.; Hansen, D.S.; Sandvang, D.

2008-01-01

The main purpose of the study was to investigate the frequency of ESBL-producing E. coli and Klebsiella strains in the Greater Copenhagen area. Four collections of strains were investigated: A) 380 consecutive E. coli and Klebsiella isolates primarily from urine, B) 200 gentamicin-resistant E. coli...... and Klebsiella isolates primarily from urine, C) 210 consecutive E. coli isolates from blood cultures, and D) 68 cefuroxime-resistant E. coli and Klebsiella isolates primarily from urine. Only one strain per patient was included. Strains with a zone diameter for cefpodoxime ...). In conclusion, the frequency of ESBL-producing E. coli and Klebsiella isolates was low in the Copenhagen area of Denmark (0.8 %). The most common ESBL genes found in our study were ctx-m and shv genes Udgivelsesdato: 2008/2...

Identification, purification and characterization of laterosporulin, a novel bacteriocin produced by Brevibacillus sp. strain GI-9.

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Pradip Kumar Singh

Full Text Available BACKGROUND: Bacteriocins are antimicrobial peptides that are produced by bacteria as a defense mechanism in complex environments. Identification and characterization of novel bacteriocins in novel strains of bacteria is one of the important fields in bacteriology. METHODOLOGY/FINDINGS: The strain GI-9 was identified as Brevibacillus sp. by 16 S rRNA gene sequence analysis. The bacteriocin produced by strain GI-9, namely, laterosporulin was purified from supernatant of the culture grown under optimal conditions using hydrophobic interaction chromatography and reverse-phase HPLC. The bacteriocin was active against a wide range of Gram-positive and Gram-negative bacteria. MALDI-TOF experiments determined the precise molecular mass of the peptide to be of 5.6 kDa and N-terminal sequencing of the thermo-stable peptide revealed low similarity with existing antimicrobial peptides. The putative open reading frame (ORF encoding laterosporulin and its surrounding genomic region was fished out from the draft genome sequence of GI-9. Sequence analysis of the putative bacteriocin gene did not show significant similarity to any reported bacteriocin producing genes in database. CONCLUSIONS: We have identified a bacteriocin producing strain GI-9, belonging to the genus Brevibacillus sp. Biochemical and genomic characterization of laterosporulin suggests it as a novel bacteriocin with broad spectrum antibacterial activity.

Identification, purification and characterization of laterosporulin, a novel bacteriocin produced by Brevibacillus sp. strain GI-9.

Science.gov (United States)

Singh, Pradip Kumar; Chittpurna; Ashish; Sharma, Vikas; Patil, Prabhu B; Korpole, Suresh

2012-01-01

Bacteriocins are antimicrobial peptides that are produced by bacteria as a defense mechanism in complex environments. Identification and characterization of novel bacteriocins in novel strains of bacteria is one of the important fields in bacteriology. The strain GI-9 was identified as Brevibacillus sp. by 16 S rRNA gene sequence analysis. The bacteriocin produced by strain GI-9, namely, laterosporulin was purified from supernatant of the culture grown under optimal conditions using hydrophobic interaction chromatography and reverse-phase HPLC. The bacteriocin was active against a wide range of Gram-positive and Gram-negative bacteria. MALDI-TOF experiments determined the precise molecular mass of the peptide to be of 5.6 kDa and N-terminal sequencing of the thermo-stable peptide revealed low similarity with existing antimicrobial peptides. The putative open reading frame (ORF) encoding laterosporulin and its surrounding genomic region was fished out from the draft genome sequence of GI-9. Sequence analysis of the putative bacteriocin gene did not show significant similarity to any reported bacteriocin producing genes in database. We have identified a bacteriocin producing strain GI-9, belonging to the genus Brevibacillus sp. Biochemical and genomic characterization of laterosporulin suggests it as a novel bacteriocin with broad spectrum antibacterial activity.

Selected wild strains of Agaricus bisporus produce high yields of mushrooms at 25°C.

Science.gov (United States)

Navarro, Pilar; Savoie, Jean-Michel

2015-01-01

To cultivate the button mushroom Agaricus bisporus in warm countries or during summer in temperate countries, while saving energy, is a challenge that could be addressed by using the biological diversity of the species. The objective was to evaluate the yield potential of eight wild strains previously selected in small scale experiments for their ability to produce mature fruiting bodies at 25°C and above. Culture units of 8 kg of compost were used. The yield expressed as weight or number per surface unit and earliness of fruiting were recorded during cultivation in climatic rooms at 17, 25 or 30°C. Only strains of A. bisporus var. burnettii were able to fruit at 30°C. At 25°C they produced the highest yields (27 kg m(-2)) and had best earliness. The yields at 25°C for the strains of A. bisporus var. bisporus ranged from 12 to 16 kg m(-2). The yield ratios 25°C/17°C ranged from 0.8 to 1.2. The variety burnettii originated in the Sonoran Desert in California showed adaptation for quickly producing fruiting bodies at high temperature when humidity conditions were favorable. Strains of the variety bisporus showed interesting potentials for their ability to produce mature fruiting bodies at higher temperature than present cultivars and might be used in breeding programs. Copyright © 2012 Revista Iberoamericana de Micología. Published by Elsevier Espana. All rights reserved.

Construction and evaluation of an exopolysaccharide-producing engineered bacterial strain by protoplast fusion for microbial enhanced oil recovery.

Science.gov (United States)

Sun, Shanshan; Luo, Yijing; Cao, Siyuan; Li, Wenhong; Zhang, Zhongzhi; Jiang, Lingxi; Dong, Hanping; Yu, Li; Wu, Wei-Min

2013-09-01

Enterobacter cloacae strain JD, which produces water-insoluble biopolymers at optimal temperature of 30°C, and a thermophilic Geobacillus strain were used to construct an engineered strain for exopolysaccharide production at high temperatures by protoplast fusion. The obtained fusant strain ZR3 produced exopolysaccharides at up to 45°C with optimal growth temperature at 35°C. The fusant produced exopolysaccharides of approximately 7.5 g/L or more at pH between 7.0 and 9.0. The feasibility of the enhancement of crude oil recovery with the fusant was tested in a sand-packed column at 40°C. The results demonstrated that bioaugmentation of the fusant was promising approach for MEOR. Mass growth of the fusant was confirmed in fermentor tests. Copyright © 2013 Elsevier Ltd. All rights reserved.

CrdR function in a curdlan-producing Agrobacterium sp. ATCC31749 strain.

Science.gov (United States)

Yu, Xiaoqin; Zhang, Chao; Yang, Liping; Zhao, Lamei; Lin, Chun; Liu, Zhengjie; Mao, Zichao

2015-02-10

Agrobacterium sp. ATCC31749 is an efficient curdlan producer at low pH and under nitrogen starvation. The helix-turn-helix transcriptional regulatory protein (crdR) essential for curdlan production has been analyzed, but whether crdR directly acts to cause expression of the curdlan biosynthesis operon (crdASC) is uncertain. To elucidate the molecular function of crdR in curdlan biosynthesis, we constructed a crdR knockout mutant along with pBQcrdR and pBQNcrdR vectors with crdR expression driven by a T5 promoter and crdR native promoter, respectively. Also, we constructed a pAG with the green fluorescent protein (GFP) gene driven by a curdlan biosynthetic operon promoter (crdP) to measure the effects of crdR expression on curdlan biosynthesis. Compared with wild-type (WT) strain biomass production, the biomass of the crdR knockout mutant was not significantly different in either exponential or stationary phases of growth. Mutant cells were non-capsulated and planktonic and produced significantly less curdlan. WT cells were curdlan-capsulated and aggregated in the stationery phase. pBQcrdR transformed to the WT strain had a 38% greater curdlan yield and pBQcrdR and pBQNcrdR transformed to the crdR mutant strain recovered 18% and 105% curdlan titers of the WT ATCC31749 strain, respectively. Consistent with its function of promoting curdlan biosynthesis, curdlan biosynthetic operon promoter (crdP) controlled GFP expression caused the transgenic strain to have higher GFP relative fluorescence in the WT strain, and no color change was observed with low GFP relative fluorescence in the crdR mutant strain as evidenced by fluorescent microscopy and spectrometric assay. q-RT-PCR revealed that crdR expression in the stationary phase was greater than in the exponential phase, and crdR overexpression in the WT strain increased crdA, crdS, and crdC expression. We also confirmed that purified crdR protein can specifically bind to the crd operon promoter region, and we inferred

Genetic Diversity Among Botulinum Neurotoxin Producing Clostridial Strains

Energy Technology Data Exchange (ETDEWEB)

Hill, K K; Smith, T J; Helma, C H; Ticknor, L O; Foley, B T; Svennson, R T; Brown, J L; Johnson, E A; Smith, L A; Okinaka, R T; Jackson, P J; Marks, J D

2006-07-06

Clostridium botulinum is a taxonomic designation for many diverse anaerobic spore forming rod-shaped bacteria which have the common property of producing botulinum neurotoxins (BoNTs). The BoNTs are exoneurotoxins that can cause severe paralysis and even death in humans and various other animal species. A collection of 174 C. botulinum strains were examined by amplified fragment length polymorphism (AFLP) analysis and by sequencing of the 16S rRNA gene and BoNT genes to examine genetic diversity within this species. This collection contained representatives of each of the seven different serotypes of botulinum neurotoxins (BoNT A-G). Analysis of the16S rRNA sequences confirmed earlier reports of at least four distinct genomic backgrounds (Groups I-IV) each of which has independently acquired one or more BoNT serotypes through horizontal gene transfer. AFLP analysis provided higher resolution, and can be used to further subdivide the four groups into sub-groups. Sequencing of the BoNT genes from serotypes A, B and E in multiple strains confirmed significant sequence variation within each serotype. Four distinct lineages within each of the BoNT A and B serotypes, and five distinct lineages of serotype E strains were identified. The nucleotide sequences of the seven serotypes of BoNT were compared and show varying degrees of interrelatedness and recombination as has been previously noted for the NTNH gene which is linked to BoNT. These analyses contribute to the understanding of the evolution and phylogeny within this species and assist in the development of improved diagnostics and therapeutics for treatment of botulism.

Selection of daunorubicin-producing strain S. Coeruleorubidus by plasma radiation technology

International Nuclear Information System (INIS)

Jiang Shichun; Wu Jianping; Bai Hua

2001-01-01

The authors reported the results of mutagenesis by nitrogen plasma radiation with energy from 65 to 80 keV and dose from 9.6 x 10 9 to 1.5 x 10 11 /cm 2 in antineoplastic antibiotics daunorubicin-producing S. Coeruleorubidus. The relationship between death rate and radiation dose was formulated by computer and the formula. It was fit to a biological single-hit curve. The obtained high-producing mutagenic strain 137 was tested for its production property. The result showed that it could increase the daunorubicin potency by 25.8% in productive tanks of fermentation

Characterization of a novel biosurfactant produced by Staphylococcus sp. strain 1E with potential application on hydrocarbon bioremediation.

Science.gov (United States)

Eddouaouda, Kamel; Mnif, Sami; Badis, Abdelmalek; Younes, Sonia Ben; Cherif, Slim; Ferhat, Samira; Mhiri, Najla; Chamkha, Mohamed; Sayadi, Sami

2012-08-01

A biosurfactant-producing bacterium (Staphylococcus sp. strain 1E) was isolated from an Algerian crude oil contaminated soil. Biosurfactant production was tested with different carbon sources using the surface tension measurement and the oil displacement test. Olive oil produced the highest reduction in surface tension (25.9 dynes cm(-1)). Crude oil presented the best substrate for 1E biosurfactant emulsification activity. The biosurfactant produced by strain 1E reduced the growth medium surface tension below 30 dynes cm(-1). This reduction was also obtained in cell-free filtrates. Biosurfactant produced by strain 1E showed stability in a wide range of pH (from 2 to 12), temperature (from 4 to 55 °C) and salinity (from 0 to 300 g l(-1)) variations. The biosurfactant produced by strain 1E belonged to lipopeptide group and also constituted an antibacterial activity againt the pathogenic bacteria such as Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Bacillus subtilis. Phenanthrene solubility in water was enhanced by biosurfactant addition. Our results suggest that the 1E biosurfactant has interesting properties for its application in bioremediation of hydrocarbons contaminated sites. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Screening of mutant strains producing phytase from A. niger by 60Co γ-ray irradiation

International Nuclear Information System (INIS)

Yang Pingping; Wang Yan; Tao Wenyi

2004-01-01

60 Co γ-ray was used to irradiate Aspergillus niger 447-92 for screening the mutant strain of producing phytase, and the effects of mutation induction were determined and analyzed. A mutant strain A. niger 496-1 with high level of phytase was selected, the phytase properties of A. niger 496-1 were analyzed

Detection and Characterization of Histamine-Producing Strains of Photobacterium damselae subsp. damselae Isolated from Mullets

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Marcello Trevisani

2017-06-01

Full Text Available Photobacterium damselae subsp. damselae (Pdd is considered to be an emerging pathogen of marine fish and has also been implicated in cases of histamine food poisoning. In this study, eight strains isolated from mullets of the genera Mugil and Liza captured in the Ligurian Sea were characterized, and a method to detect histamine-producing Pdd from fish samples was developed. The histamine-producing potential of the strains was evaluated in culture media (TSB+ using a histamine biosensor. Subsequently, two strains were used to contaminate mackerel fillets (4 or 40 CFU/g, simulating a cross-contamination on the selling fish stalls. Sample homogenates were enriched in TSB+. The cultures were then inoculated on thiosulfate-citrate-bile salts-sucrose agar (TCBS and the dark green colonies were cultured on Niven agar. The violet isolates were characterized using specific biochemical and PCR based tests. All Pdd strains were histamine producers, yielding concentration varying from 167 and 8977 µg/mL in TSB+ cultures incubated at 30 °C for 24 h. Pdd colonies were detected from the inoculated mackerel samples and their histidine decarboxylase gene was amplified using species-specific primer pairs designed for this study. The results indicate that mullets can be source of Pdd and the fish retailers needs to evaluate the risk posed by cross-contamination on the selling fish stalls.

Isolation, Fermentation Optimization and Performance Studies of a Novel Biosurfactant Producing Strain Bacillus amyloliquefaciens

OpenAIRE

Zhang, W.; Zhang, X.; Cui, H.

2015-01-01

In this research, biosurfactant-producing bacteria were isolated from the outlet sludge of a canteen and one promising strain was identified through 16S rDNA sequence as Bacillus amyloliquefaciens. This strain can utilize water-soluble carbon source and the FT-IR analysis indicated the biosurfactant was probably glycolipids. Further factors (fermentation time, temperature, carbon source, nitrogen source, ion concentration) affecting the biosurfactant production were determined. The optimum fe...

Bacillus amyloliquefaciens SUBSP. plantarum PROBIOTIC STRAINS AS PROTEASE PRODUCERS

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E. V. Маtseliukh

2015-04-01

Full Text Available Proteases from probiotic strains of the genus Bacillus, just like the antibiotics, bacteriocins and other hydrolytic enzymes, are one of the main factors that determine their biological activity. The aim of this work was to study the synthesis and biochemical properties of proteases from two strains Bacillus amyloliquefaciens subsp. plantarum UCM B-5139 and UCM B-5140 that included in the probiotic Endosporin. The cultivation of strains was carried out in flasks under rotating for two days. The influence of physico-chemical parameters of the reaction medium on proteolytic activity was studied on partially purified protease preparations. Lytic activity was determined by turbidimetric method. On the second day of cultivation B. amyloliquefaciens subsp. plantarum UCM В-5139 and UCM В-5140 synthesized the metal-dependent peptidase and serine protease, respectively. The optimum conditions of their action were the following: temperature 37–40 °C and pH 6.5–7.0. Isolated proteases are able to lyse the living cells of Staphylococcus aureus and Candida albicans. Thus we demonstrated that B. amyloliquefaciens subsp. plantarum UCM B-5140 and UCM B-5139, included in the probiotic veterinary preparation Endosporin, produced proteolytic enzymes that hydrolyze the native insoluble proteins (elastin, fibrin and collagen. These enzymes belong to the group of neutral metal-dependent and serine proteases. They are active under physiological conditions against gram-positive bacteria and yeasts. The application of these proteases in biotechnology is considered.

Whole-Genome Characterization and Strain Comparison of VT2f-Producing Escherichia coli Causing Hemolytic Uremic Syndrome

Science.gov (United States)

Michelacci, Valeria; Bondì, Roslen; Gigliucci, Federica; Franz, Eelco; Badouei, Mahdi Askari; Schlager, Sabine; Minelli, Fabio; Tozzoli, Rosangela; Caprioli, Alfredo; Morabito, Stefano

2016-01-01

Verotoxigenic Escherichia coli infections in humans cause disease ranging from uncomplicated intestinal illnesses to bloody diarrhea and systemic sequelae, such as hemolytic uremic syndrome (HUS). Previous research indicated that pigeons may be a reservoir for a population of verotoxigenic E. coli producing the VT2f variant. We used whole-genome sequencing to characterize a set of VT2f-producing E. coli strains from human patients with diarrhea or HUS and from healthy pigeons. We describe a phage conveying the vtx2f genes and provide evidence that the strains causing milder diarrheal disease may be transmitted to humans from pigeons. The strains causing HUS could derive from VT2f phage acquisition by E. coli strains with a virulence genes asset resembling that of typical HUS-associated verotoxigenic E. coli. PMID:27584691

Screening and identification of lactic acid bacteria strains with high acid-producing from traditional fermented yak yogurt

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Chen Xiaoyong

2017-01-01

Full Text Available A total of 57 strains of lactic acid bacteria (LAB were isolated and purified from traditional fermented Yak Yogurt in Hongyuan-Sichuan and Yangbajing-Tibet. The strains with high acid-produced were screened by soluble calcium circle and titratable acidity determination. The five strains, 7-1, 22-1, 28-1, 34-1 and 62-1, possessed the high acid-producing and the value of titratable acidity is 196.2, 191.1, 192.2, 194.8 and 200.2 T respectively. Based on 16S rDNA sequence analysis, 22-1 was identified as Lactococcus lactis subsp. lactis, 28-1 as Lactobacillus casei, 34-1 as Lactobacillus fermentium, 7-1 and 62-1 as Enterococcus durans. This study could provide the evidence for researching fermentation strains to improve yogurt quality.

Isolation and characterization of a biosurfactant producing strain, Brevibacilis brevis HOB1.

Science.gov (United States)

Haddad, Namir I A; Wang, Ji; Mu, Bozhong

2008-12-01

Biosurfactant-producing bacteria were isolated from the production water of an oil field. Isolates were screened for biosurfactant production using surface tension test. The highest reduction of surface tension was achieved with a bacterial strain which was identified by 16S rRNA gene sequencing as Brevibacilis brevis HOB1. It has been investigated using different carbon and nitrogen sources. It showed that the strain was able to grow and reduce the surface tension of the broth to 29 mN/m on commercial sugar and maltose, and to 32 mN/m on glucose after 72 h of growth. The maximum amount of biosurfactant was obtained when nitrate ions were supplied as nitrogen source. Biosurfactant produced by Brevibacilis brevis HOB1 was confirmed as a lipopeptide class of biosurfactant using TLC test and mass spectra. Lipopeptide isoforms were isolated from cell-free supernatants by acid-precipitation followed by one step of chromatographic separation on solid-phase ODS C18 column. The separation was confirmed by HPLC and ESI Q-TOF MS spectroscopy. Comparing the mass data obtained and the mass numbers reported for the lipopeptide complexes from other strains, it can be concluded that the major lipopeptide product of Brevibacilis brevis HOB1 is the surfactin isoform. This lipopeptide showed strong antibacterial and antifungal activity. It is a candidate for the biocontrol of pathogens in agriculture and other industries.

Draft Genome Sequence of the Microbispora sp. Strain ATCC-PTA-5024, Producing the Lantibiotic NAI-107

DEFF Research Database (Denmark)

Sosio, M.; Gallo, G.; Pozzi, R.

2014-01-01

We report the draft genome sequence of Microbispora sp. strain ATCC-PTA-5024, a soil isolate that produces NAI-107, a new lantibiotic with the potential to treat life-threatening infections caused by multidrug-resistant Gram-positive pathogens. The draft genome of strain Microbispora sp. ATCC...

Mechanical strain stimulates vasculogenesis and expression of angiogenesis guidance molecules of embryonic stem cells through elevation of intracellular calcium, reactive oxygen species and nitric oxide generation.

Science.gov (United States)

Sharifpanah, Fatemeh; Behr, Sascha; Wartenberg, Maria; Sauer, Heinrich

2016-12-01

Differentiation of embryonic stem (ES) cells may be regulated by mechanical strain. Herein, signaling molecules underlying mechanical stimulation of vasculogenesis and expression of angiogenesis guidance cues were investigated in ES cell-derived embryoid bodies. Treatment of embryoid bodies with 10% static mechanical strain using a Flexercell strain system significantly increased CD31-positive vascular structures and the angiogenesis guidance molecules plexinB1, ephrin B2, neuropilin1 (NRP1), semaphorin 4D (sem4D) and robo4 as well as vascular endothelial growth factor (VEGF), fibroblast growth factor-2 (FGF-2) and platelet-derived growth factor-BB (PDGF-BB) as evaluated by Western blot and real time RT-PCR. In contrast ephrin type 4 receptor B (EphB4) expression was down-regulated upon mechanical strain, indicating an arterial-type differentiation. Robo1 protein expression was modestly increased with no change in mRNA expression. Mechanical strain increased intracellular calcium as well as reactive oxygen species (ROS) and nitric oxide (NO). Mechanical strain-induced vasculogenesis was abolished by the NOS inhibitor L-NAME, the NADPH oxidase inhibitor VAS2870, upon chelation of intracellular calcium by BAPTA as well as upon siRNA inactivation of ephrin B2, NRP1 and robo4. BAPTA blunted the strain-induced expression of angiogenic growth factors, the increase in NO and ROS as well as the expression of NRP1, sem4D and plexinB1, whereas ephrin B2, EphB4 as well as robo1 and robo4 expression were not impaired. Mechanical strain stimulates vasculogenesis of ES cells by the intracellular messengers ROS, NO and calcium as well as by upregulation of angiogenesis guidance molecules and the angiogenic growth factors VEGF, FGF-2 and PDGF-BB. Copyright © 2016 Elsevier B.V. All rights reserved.

Characterization of Partially Purified Bacteriocin Like Substance (BLIS Produced by Probiotic Lactobacillus Strains

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Saeed Ismail Khanian

2014-05-01

Full Text Available Background: There is an increasing interest in search for antimicrobial peptides (bacteriocins and bacteriocin-like compounds produced by lactic acid bacteria (LAB because of their potential to be used as antimicrobial agents for improving the safety of food products. Objectives: The main objective of study was to evaluate the antibacterial potential of locally isolated Lactic Acid bacteria (LAB and determine their bacteriocin producing ability in in-vitro conditions. Materials and Methods: The antibacterial activity of 77 isolated LAB strains was tested against a number of pathogens by well-diffusion method. The isolates demonstrating antimicrobial potential were selected and tested for the production of bacteriocin or bacteriocin like substance. The bacteriocin produced by two of the isolates were partially purified and characterized. Results: The results indicated the neutralized supernatant fluid of two of the isolates identified as L. brevis LB32 and L. pentosus LP05, were active against the growth of Listeria monocytogenes, Salmonella enteritidis, Shigella dysenteriae, Staphylococcus aureus and Streptococcus pneumoniae. Additionally, L. brevis LB32 was able to inhibit the growth of Salmonella typhi and Klebsiella pneumoniae, while, S. pnuemoniae and L. monocytogenes appeared to be the most sensitive strain as apparent by highest zone of inhibition against these pathogens, respectively. The antimicrobial activity in the supernatant fluids of the mentioned strains remained unaffected after treating with enzymes catalase, lipase and lysozyme, while were strongly sensitive to the action of proteolytic enzymes, suggesting the presence of bacteriocin like inhibitory substance (BLIS in the two isolates. The inhibitory substance produced by the two isolates appeared heat resistant and tolerated 100˚C and 121˚C for 55 minutes and 20 minutes, respectively. Partial purification of the concentrated culture supernatant fluids of L. brevis LB32 and L

Characterization of high exopolysaccharide-producing Lactobacillus strains isolated from mustard pickles for potential probiotic applications.

Science.gov (United States)

Huang, Jing-Yao; Kao, Cheng-Yen; Liu, We-Sin; Fang, Tony J

2017-06-01

The aim of this study was to characterize high exopolysaccharide (EPS)-producing lactic acid bacteria (LAB) isolated from mustard pickles in Taiwan for potential probiotic applications. Among 39 collected LAB strains, four most productive EPS-producing strains were selected for further analysis. Comparative analyses of 16S rDNA genes rpoA and pheS sequences demonstrated that these strains were members of Lactobacillus plantarum-group (LPG). NCD 2, NLD 4, SLC 13, and NLD 16 showed survival rates of 95.83% ± 0.49%, 95.07% ± 0.64%, 105.84% ± 0.82%, and 99.65% ± 0.31% under simulated gastrointestinal conditions, respectively. No cytotoxic effects on macrophage RAW 264.7 cells were observed when they were treated with a low dose (1 μg/ml) of stimulants extracted from the tested LAB strains. The production of nitric oxide in RAW 264.7 cells incubated with various LAB stimulants showed a dose-dependent increase. Among the four strains, SLC 13 showed higher inhibitory activity on growth of Enterococcus faecalis (BCRC 12302) and Yersinia enterocolitica (BCRC 10807). NLD 4 showed strong inhibitory activity against Escherichia coli O157:H7 (ATCC 43894) as compared with the other three strains. In summary, our results suggest that Lactobacillus pentosus SLC 13 may be a good candidate for probiotic applications and for development of antibacterial compounds. [Int Microbiol 20(2):75-84 (2017)]. Copyright© by the Spanish Society for Microbiology and Institute for Catalan Studies.

Supplementary Material for: In silico screening for candidate chassis strains of free fatty acid-producing cyanobacteria

KAUST Repository

Motwalli, Olaa Amin

2017-01-01

Abstract Background Finding a source from which high-energy-density biofuels can be derived at an industrial scale has become an urgent challenge for renewable energy production. Some microorganisms can produce free fatty acids (FFA) as precursors towards such high-energy-density biofuels. In particular, photosynthetic cyanobacteria are capable of directly converting carbon dioxide into FFA. However, current engineered strains need several rounds of engineering to reach the level of production of FFA to be commercially viable; thus new chassis strains that require less engineering are needed. Although more than 120 cyanobacterial genomes are sequenced, the natural potential of these strains for FFA production and excretion has not been systematically estimated. Results Here we present the FFA SC (FFASC), an in silico screening method that evaluates the potential for FFA production and excretion of cyanobacterial strains based on their proteomes. A literature search allowed for the compilation of 64 proteins, most of which influence FFA production and a few of which affect FFA excretion. The proteins are classified into 49 orthologous groups (OGs) that helped create rules used in the scoring/ranking of algorithms developed to estimate the potential for FFA production and excretion of an organism. Among 125 cyanobacterial strains, FFASC identified 20 candidate chassis strains that rank in their FFA producing and excreting potential above the specifically engineered reference strain, Synechococcus sp. PCC 7002. We further show that the top ranked cyanobacterial strains are unicellular and primarily include Prochlorococcus (order Prochlorales) and marine Synechococcus (order Chroococcales) that cluster phylogenetically. Moreover, two principal categories of enzymes were shown to influence FFA production the most: those ensuring precursor availability for the biosynthesis of lipids, and those involved in handling the oxidative stress associated to FFA synthesis

Exopolysaccharides produced by marine bacteria and their applications as glycosaminoglycan-like molecules.

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Christine eDELBARRE-LADRAT

2014-10-01

Full Text Available Although polysaccharides are ubiquitous and the most abundant renewable bio-components, their studies, covered by the glycochemistry and glycobiology fields, remain a challenge due to their high molecular diversity and complexity.Polysaccharides are industrially used in food products; human therapeutics fall into a more recent research field and pharmaceutical industry is looking for more and more molecules with enhanced activities. Glycosaminoglycans (GAGs found in animal tissues play a critical role in cellular physiological and pathological processes as they bind many cellular components. Therefore, they present a great potential for the design and preparation of therapeutic drugs.On the other hand, microorganisms producing exopolysaccharides (EPS are renewable resources meeting well the actual industrial demand. In particular, the diversity of marine microorganisms is still largely unexplored offering great opportunities to discover high value products such as new molecules and biocatalysts.EPS-producing bacteria from the marine environment will be reviewed with a focus on marine-derived EPS from bacteria isolated from deep-sea hydrothermal vents. Information on chemical and structural features, putative pathways of biosynthesis, novel strategies for chemical and enzymatic modifications and potentialities in the biomedical field will be provided. An integrated approach should be used to increase the basic knowledge on these compounds and their applications; new clean environmentally friendly processes for the production of carbohydrate bio-active compounds should also be proposed for a sustainable industry.

Exopolysaccharides produced by marine bacteria and their applications as glycosaminoglycan-like molecules.

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Delbarre-Ladrat, Christine; Sinquin, Corinne; Lebellenger, Lou; Zykwinska, Agata; Colliec-Jouault, Sylvia

2014-10-01

Although polysaccharides are ubiquitous and the most abundant renewable bio-components, their studies, covered by the glycochemistry and glycobiology fields, remain a challenge due to their high molecular diversity and complexity. Polysaccharides are industrially used in food products; human therapeutics fall into a more recent research field and pharmaceutical industry is looking for more and more molecules with enhanced activities. Glycosaminoglycans (GAGs) found in animal tissues play a critical role in cellular physiological and pathological processes as they bind many cellular components. Therefore, they present a great potential for the design and preparation of therapeutic drugs. On the other hand, microorganisms producing exopolysaccharides (EPS) are renewable resources meeting well the actual industrial demand. In particular, the diversity of marine microorganisms is still largely unexplored offering great opportunities to discover high value products such as new molecules and biocatalysts. EPS-producing bacteria from the marine environment will be reviewed with a focus on marine-derived EPS from bacteria isolated from deep-sea hydrothermal vents. Information on chemical and structural features, putative pathways of biosynthesis, novel strategies for chemical and enzymatic modifications and potentialities in the biomedical field will be provided. An integrated approach should be used to increase the basic knowledge on these compounds and their applications; new clean environmentally friendly processes for the production of carbohydrate bio-active compounds should also be proposed for a sustainable industry.

Characterization of volatile compounds produced by Lactobacillus helveticus strains in a hard cheese model.

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Cuffia, Facundo; Bergamini, Carina V; Wolf, Irma V; Hynes, Erica R; Perotti, María C

2018-01-01

Starter cultures of Lactobacillus helveticus used in hard cooked cheeses play an important role in flavor development. In this work, we studied the capacity of three strains of L. helveticus, two autochthonous (Lh138 and Lh209) and one commercial (LhB02), to grow and to produce volatile compounds in a hard cheese extract. Bacterial counts, pH, profiles of organic acids, carbohydrates, and volatile compounds were analyzed during incubation of extracts for 14 days at 37 ℃. Lactobacilli populations were maintained at 10 6 CFU ml -1 for Lh138, while decreases of approx. 2 log orders were found for LhB02 and Lh209. Both Lh209 and LhB02 slightly increased the acetic acid content whereas mild increase in lactic acid was produced by Lh138. The patterns of volatiles were dependent on the strain which reflect their distinct enzymatic machineries: LhB02 and Lh209 produced a greater diversity of compounds, while Lh138 was the least producer strain. Extracts inoculated with LhB02 and Lh 209 were characterized by ketones, esters, alcohols, aldehydes, and acids, whereas in the extracts with Lh138 the main compounds belonged to aromatic, aldehydes, and ketones groups. Therefore, Lh209 and LhB02 could represent the best cheese starters to improve and intensify the flavor, and even a starter composed by combinations of LhB02 or Lh209 with Lh138 could also be a strategy to diversify cheese flavor.

Genomic mutational analysis of the impact of the classical strain improvement program on β-lactam producing Penicillium chrysogenum

NARCIS (Netherlands)

Salo, Oleksandr V; Ries, Marco; Medema, Marnix H; Lankhorst, Peter P; Vreeken, Rob J; Bovenberg, Roel A L; Driessen, Arnold J M

2015-01-01

BACKGROUND: Penicillium chrysogenum is a filamentous fungus that is employed as an industrial producer of β-lactams. The high β-lactam titers of current strains is the result of a classical strain improvement program (CSI) starting with a wild-type like strain more than six decades ago. This

Growth characteristics and enzyme production optimization of lipase Producing Strain

Science.gov (United States)

Zheng, Chaocheng

2018-01-01

55 samples from different regions were selected and screened by Rhodamine B flat transparent circle method to observe lipase producing effect, among which, LHY-1, identified as Serratia sp. has the characteristics of fast growth, high enzyme production and stable ability. The colony of this strain is white, the edge is smooth and tidy, the surface is moist, the cell is straight, rod-shaped, gram negative, 0.1-0.2 μm in diameter and, length 0.3-0.5 μm in length.

Influence of gastrointestinal system conditions on adhesion of exopolysaccharide-producing Lactobacillus delbrueckii subsp. bulgaricus strains to caco-2 cells

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Derya Onal Darilmaz

2011-10-01

Full Text Available This study aimed to assess the transit tolerance of potential probiotic dairy Lactobacillus strains in human uppergastrointestinal tract in vitro, and to evaluate the effect of EPS production on the viability and adhesion of these strains. Survival and adhesion of two exopolysaccharide (EPS-producing L. delbrueckii subsp. bulgaricus strains (B3 and B2 and E. coli ATCC11229 were assessed after the exposure of different pH (gastric juice and gastric plus pancreatic juice challenges. In the artificial gastric juice (pH 2, both the viability of the strain B3 and B2 was decreased. Artificial juice treatments significantly reduced the adhesion to caco-2 cells (P< 0.05. High EPS-producing B3 survived better in the adverse gastrointestinal conditions and showed better ability of adhesion to Caco-2 cells when assessed for competition with E. coli ATCC 11229 compared to low EPS-producing B2. This investigation showed that EPS production could be affected or be involved in the viability, adherence and competition of L. delbrueckii subsp. bulgaricus strains and support the potential of B3 strain for development of new probiotic products.

Characterization of ESBL-producing Escherichia coli and Klebsiella pneumoniae strains isolated from urine of nonhospitalized patients in the Zagreb region

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Branka Bedenić,

2010-02-01

Full Text Available Aim To determine the prevalence of ESBL-producing Escherichia coli and Klebsiella pneumoniae strains isolated from urine of nonhospitalized patients during a three-year period, to determine their antibiotic susceptibility, investigate the transfer of ESBL genes with cotransfer of resistance and to characterize isolated beta-lactamases. Methods Antimicrobial susceptibility was determined by disk diffusion and broth microdilution methods. The double-disk test was used for ESBL detection. Transfer of resistance was performed by broth mating method and characterization of isolated beta-lactamases by polymerase chain reaction. Results The prevalence of ESBL-producing E. coli was 1.5% and of K. pneumoniae 4.1% with its different distribution according to patients`age and gender. ESBL-producing K. pneumoniae showed high resistance rates to aminoglycosides, cotrimoxazole, nitrofurantoin and quinolones while ESBL-producing E. coli isolates, with exception of high aminoglycoside resistance, showed low resistance rates to other antibiotics. Successful conjugation of ESBL genes was obtained with 25% E. coli and 76.2% K. pneumoniae strains. Comparing to E. coli, K. pneumoniae strains showed higher rates of aminoglycosideand cotrimoxazole resistance cotransfer. Beta-lactamases of investigated strains belonged to TEM, SHV and CTX-M families.Conclusion The existence of multiple-resistant ESBL-producing E. coli and K. pneumoniae strains was confirmed in observed outpatient population. ESBL-producing K. pneumoniae isolates, in contrast toESBL-producing E. coli, showed higher resistance rates to non-beta-lactam antibiotics, probably caused by cotransfer of resistance genes located on the same plasmid as ESBL genes. It is important to monitor the prevalence of such strains and their possible spreading in the outpatient population of the Zagreb region

Genome Sequence of Lactococcus lactis subsp. lactis NCDO 2118, a GABA-Producing Strain

DEFF Research Database (Denmark)

Oliveira, Letícia C; Saraiva, Tessália D L; Soares, Siomar C

2014-01-01

Lactococcus lactis subsp. lactis NCDO 2118 is a nondairy lactic acid bacterium, a xylose fermenter, and a gamma-aminobutyric acid (GABA) producer isolated from frozen peas. Here, we report the complete genome sequence of L. lactis NCDO 2118, a strain with probiotic potential activity....

Isolation and characterization of exopolysaccharide produced by Vibrio harveyi strain VB23.

Science.gov (United States)

Bramhachari, P V; Dubey, S K

2006-11-01

The aim of the study was to isolate and characterize exopolysaccharide (EPS) produced by Vibrio harveyi strain VB23. Growth and EPS production by V. harveyi strain VB23, was studied in mineral salts medium supplemented with NaCl (1.5%) and glucose (0.2%). The rate of EPS production in batch cultures was highest during the late log phase of growth when compared with stationary growth phase. The exopolymer was recovered from the culture supernatant by using a cold ethanol precipitation-dialysis procedure. Chemical analyses of EPS revealed that it is primarily composed of neutral sugars, uronic acids, proteins and sulfates. The purified EPS revealed prominent functional reactive groups, such as hydroxyl, carboxylic and amides, which correspond to a typical heteropolymeric polysaccharide and the EPS, also possessed good emulsification activity. The gas chromatographic analysis of an alditol acetate-derivatized sample of EPS revealed that it is composed primarily of galactose and glucose. Minor components found were rhamnose, fucose, ribose, arabinose, xylose and mannose. The EPS produced by V. harveyi strain VB23 is a heteropolysaccharide possessing good emulsification activity. EPS was readily isolated from culture supernatants, which suggests that the EPS was a slime-like EPS. This is the first report of EPS characterization in luminous V. harveyi bacteria, which describes the isolation and characterization of an EPS expressed by V. harveyi. The results of the study contributes significantly towards an understanding of the chemical composition and applications of the EPS in environmental biotechnology and bioremediation.

Purification and characterization of the bacteriocin Thuricin Bn1 produced by Bacillus thuringiensis subsp. kurstaki Bn1 isolated from a hazelnut pest.

Science.gov (United States)

Ugras, Serpil; Sezen, Kazim; Kati, Hatice; Demirbag, Zihni

2013-02-01

A novel bioactive molecule produced by Bacillus thuringiensis subsp. kurstaki Bn1 (Bt-Bn1), isolated from a common pest of hazelnut, Balaninus nucum L. (Coleoptera: Curculionidae), was determined, purified, and characterized in this study. The Bt-Bn1 strain was investigated for antibacterial activity with an agar spot assay and well diffusion assay against B. cereus, B. weinhenstephenensis, L. monocytogenes, P. savastanoi, P. syringae, P. lemoignei, and many other B. thuringiensis strains. The production of bioactive molecule was determined at the early logarithmic phase in the growth cycle of strain Bt-Bn1 and its production continued until the beginning of the stationary phase. The mode of action of this molecule displayed bacteriocidal or bacteriolytic effect depending on the concentration. The bioactive molecule was purified 78-fold from the bacteria supernatant with ammonium sulfate precipitation, dialysis, ultrafiltration, gel filtration chromatography, and HPLC, respectively. The molecular mass of this molecule was estimated via SDS-PAGE and confirmed by the ESI-TOFMS as 3,139 Da. The bioactive molecule was also determined to be a heat-stable, pH-stable (range 6-8), and proteinase K sensitive antibacterial peptide, similar to bacteriocins. Based on all characteristics determined in this study, the purified bacteriocin was named as thuricin Bn1 because of the similarities to the previously identified thuricin-like bacteriocin produced by the various B. thuringiensis strains. Plasmid elution studies showed that gene responsible for the production of thuricin Bn1 is located on the chromosome of Bt-Bn1. Therefore, it is a novel bacteriocin and the first recorded one produced by an insect originated bacterium. It has potential usage for the control of many different pathogenic and spoilage bacteria in the food industry, agriculture, and various other areas.

Lignocellulose-Adapted Endo-Cellulase Producing Streptomyces Strains for Bioconversion of Cellulose-Based Materials.

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Ventorino, Valeria; Ionata, Elena; Birolo, Leila; Montella, Salvatore; Marcolongo, Loredana; de Chiaro, Addolorata; Espresso, Francesco; Faraco, Vincenza; Pepe, Olimpia

2016-01-01

Twenty-four Actinobacteria strains, isolated from Arundo donax, Eucalyptus camaldulensis and Populus nigra biomass during natural biodegradation and with potential enzymatic activities specific for the degradation of lignocellulosic materials, were identified by a polyphasic approach. All strains belonged to the genus Streptomyces ( S .) and in particular, the most highly represented species was Streptomyces argenteolus representing 50% of strains, while 8 strains were identified as Streptomyces flavogriseus (synonym S. flavovirens ) and Streptomyces fimicarius (synonyms Streptomyces acrimycini, Streptomyces baarnensis, Streptomyces caviscabies , and Streptomyces flavofuscus ), and the other four strains belonged to the species Streptomyces drozdowiczii, Streptomyces rubrogriseus, Streptomyces albolongus , and Streptomyces ambofaciens . Moreover, all Streptomyces strains, tested for endo and exo-cellulase, cellobiase, xylanase, pectinase, ligninase, peroxidase, and laccase activities using qualitative and semi-quantitative methods on solid growth medium, exhibited multiple enzymatic activities (from three to six). The 24 strains were further screened for endo-cellulase activity in liquid growth medium and the four best endo-cellulase producers ( S. argenteolus AE58P, S. argenteolus AE710A, S. argenteolus AE82P, and S. argenteolus AP51A) were subjected to partial characterization and their enzymatic crude extracts adopted to perform saccharification experiments on A. donax pretreated biomass. The degree of cellulose and xylan hydrolysis was evaluated by determining the kinetics of glucose and xylose release during 72 h incubation at 50°C from the pretreated biomass in the presence of cellulose degrading enzymes (cellulase and β-glucosidase) and xylan related activities (xylanase and β-xylosidase). The experiments were carried out utilizing the endo-cellulase activities from the selected S. argenteolus strains supplemented with commercial β-gucosidase and

[Co-occurence of indol-producing bacterial strains in the vagina of women infected with Chlamydia trachomatis].

Science.gov (United States)

Romanik, Małgorzata; Martirosian, Gayane; Wojciechowska-Wieja, Anna; Cieślik, Katarzyna; Kaźmierczak, Wojciech

2007-08-01

The aim of this study was to determine if cervicitis, caused by Chlamydia trachomatis (C. trachomatis), has an influence on the frequency of occurrence of selected aerobic and anaerobic bacterial strains, connected with etiology of aerobic vaginitis (AV) and bacterial vaginosis (BV). Indole-producing bacteria have received particular attention due to their possibly inductive role in chronic cervicitis caused by C. trachomatis. The swabs from vagina and cervical canal have been obtained from 122 women (aged 18-40). The presence of C. trachomatis antigen had been detected and diagnosed with the help of direct immunofluorescence, BV with Amesl and Nugent criteria, whereas the AV with Donders criteria. The identification of the bacterial strains isolated from vagina has been performed according to classical microbiological diagnostics. Disruption of vaginal microflora (4-10 in Nugent score) was determined in 11,5% of observed women. AV was diagnosed in 4.5% women with chlamydial cervicitis, BV was diagnosed in 10.9% and 5.45% of these women, on the basis of Amsel and Nugent criteria respectively. Indole-producing bacterial strains connected with BV and AV (Peptostreptococcus anaerobius, Propionibacterium acnes, Escherichia coli) have been isolated significantly more often from vagina of women infected with C trachomatis (p = 0.0405, chi2 = 4.20) and these findings confirm co-importance of indole-producing bacterial strains in cervicitis caused by C trachomatis .

Structural identification of lipopeptide biosurfactants produced by Bacillus subtilis strains grown on the media obtained from renewable natural resources.

Science.gov (United States)

Paraszkiewicz, Katarzyna; Bernat, Przemysław; Kuśmierska, Anna; Chojniak, Joanna; Płaza, Grażyna

2018-03-01

The aim of the study was to identify and characterize lipopeptide (LP) biosurfactants produced by two Bacillus subtilis strains (KP7 and I'-1a) grown on various media prepared from renewable natural resources: two different brewery wastewaters (BW#4 and BW#6), 2% beet molasses (M), apple peels extract (APE) supplemented with 0.25% of yeast extract (YE) or 0.25% peptone (P), and similarly supplemented carrot peels extract (CPE). In all used media both strains retained their individual LP production signature characterized by surfactin and iturin overproduction exhibited by KP7 and I'-1a strain, respectively. The production level and the structural diversity of synthesized LPs were dependent on the medium composition. In the CPE+YE medium it was higher than the yield obtained in Luria-Bertani (140.6 and 100.3 mg L -1 , respectively). Surfactins were produced by both strains as a mixture of four homologues (C13-C16) with the domination of variant C14. All other broths prepared from renewable resources strongly stimulated the iturin production by I'-1a strain with the exception of BW media. The highest iturin concentration (428.7 mg L -1 ) obtained in the CPE+P culture of I'-1a strain was about seven-fold higher than in LB. In all cultures only iturin A was identified. Among four iturin homologues (C13-16) produced by I'-1a strain, the highest relative contents of C16 variant (70-80%) were calculated for samples obtained from APE+P and CPE+P media. The obtained data indicate that the waste composition has an influence on both the types and amounts of biosurfactants produced by studied B. subtilis strains. Copyright © 2017 Elsevier Ltd. All rights reserved.

Comparative Genomic and Phylogenetic Analysis of a Shiga Toxin Producing Shigella sonnei (STSS Strain

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Domonkos Sváb

2017-05-01

Full Text Available Shigella strains are important agents of bacillary dysentery, and in recent years Shigella sonnei has emerged as the leading cause of shigellosis in industrialized and rapidly developing countries. More recently, several S. sonnei and Shigella flexneri strains producing Shiga toxin (Stx have been reported from sporadic cases and from an outbreak in America. In the present study we aimed to shed light on the evolution of a recently identified Shiga toxin producing S. sonnei (STSS isolated in Europe. Here we report the first completely assembled whole genome sequence of a multidrug resistant (MDR Stx-producing S. sonnei (STSS clinical strain and reveal its phylogenetic relations. STSS 75/02 proved to be resistant to ampicillin, streptomycin, tetracycline, chloramphenicol, thrimetoprim, and sulfomethoxazol. The genome of STSS 75/02 contains a 4,891,717 nt chromosome and seven plasmids including the 214 kb invasion plasmid (pInv harboring type III secretion system genes and associated effectors. The chromosome harbors 23 prophage regions including the Stx1 converting prophage. The genome carries all virulence determinants necessary for an enteroinvasive lifestyle, as well as the Stx1 encoding gene cluster within an earlier described inducible converting prophage. In silico SNP genotyping of the assembled genome as well as 438 complete or draft S. sonnei genomes downloaded from NCBI GenBank revealed that S. sonnei 75/02 belongs to the more recently diverged global MDR lineage (IIIc. Targeted screening of 1131 next-generation sequencing projects taken from NCBI Short Read Archive of confirms that only a few S. sonnei isolates are Stx positive. Our results suggest that the acquisition of Stx phages could have occurred in different environments as independent events and that multiple horizontal transfers are responsible for the appearance of Stx phages in S. sonnei strains.

Selection of bacteriocin producer strains of lactic acid bacteria from a dairy environment.

Science.gov (United States)

Lasagno, M; Beoleito, V; Sesma, F; Raya, R; Font de Valdez, G; Eraso, A

2002-01-01

Two strains showing bacteriocin production were selected from a total of 206 lactic acid bacteria isolated from samples of milk, milk serum, whey and homemade cheeses in Southern Cordoba, Argentina. This property was detected by means of well diffusion assays. The strains were identified as Enterococcus hirae and Enterococcus durans. The protein nature of those substances was proved by showing their sensitivity to type IV and XXV proteases, papaine, trypsin, pepsin and K proteinase. The bacteriocins inhibited the growth of Listeria monocytogenes, Bacillus cereus, Clostridium perfringes and two strains of Staphylococcus aureus, an A-enterotoxin and a B-enterotoxin producers. All of these bacteria are common pathogens usually associated with food borne diseases (ETA). These lactic acid bacteria or their bacteriocins could be suitable candidates for food preservation and specially useful in the our regional dairy industry.

Isolation and characterisation of an enterocin P-producing Enterococcus lactis strain from a fresh shrimp (Penaeus vannamei).

Science.gov (United States)

Ben Braïek, Olfa; Ghomrassi, Hamdi; Cremonesi, Paola; Morandi, Stefano; Fleury, Yannick; Le Chevalier, Patrick; Hani, Khaled; Bel Hadj, Omrane; Ghrairi, Taoufik

2017-06-01

Screening for lactic acid bacteria (LAB) from fresh shrimp samples (Penaeus vannamei) collected from retail seafood markets in the Tunisian's coast, resulted in the isolation of an Enterococcus strain termed Q1. This strain was selected for its antagonistic activity against pathogenic bacteria such as Listeria monocytogenes, Pseudomonas aeruginosa, Lactococcus garvieae and against fungi (Aspergillus niger and Fusarium equiseti). The Q1 strain was characterised using standard morphological and biochemical tests, growth assays at different temperatures, pH and salinity. 16S rRNA, rpoA and pheS gene sequencing, as well as the 16S-23S rRNA intergenic spacer analyses, were combined to identify strain Q1 as a strain of Enterococcus lactis. The bacteriocin produced by E. lactis Q1 is thermostable, active in the pH range from 4.0 to 9.0 and has a bactericidal mode of action. The enterocin P structural gene was detected by specific PCR in strain E. lactis Q1, which is in good agreement with SDS-PAGE data of the purified bacteriocin. A lack of significant antibiotic resistance genes and virulence determinants was confirmed by specific PCRs. This work provides the first description of an enterocin P producer E. lactis strain isolated from a fresh shrimp. Based on its safety properties (absence of haemolytic activity, virulence factors and antibiotic resistance genes), this strain has the potential to be used as a natural additive or adjunct protective culture in food biopreservation and/or probiotic culture.

Tribochemical synthesis of nano-lubricant films from adsorbed molecules at sliding solid interface: Tribo-polymers from α-pinene, pinane, and n-decane

Science.gov (United States)

He, Xin; Barthel, Anthony J.; Kim, Seong H.

2016-06-01

The mechanochemical reactions of adsorbed molecules at sliding interfaces were studied for α-pinene (C10H16), pinane (C10H18), and n-decane (C10H22) on a stainless steel substrate surface. During vapor phase lubrication, molecules adsorbed at the sliding interface could be activated by mechanical shear. Under the equilibrium adsorption condition of these molecules, the friction coefficient of sliding steel surfaces was about 0.2 and a polymeric film was tribochemically produced. The synthesis yield of α-pinene tribo-polymers was about twice as much as pinane tribo-polymers. In contrast to these strained bicyclic hydrocarbons, n-decane showed much weaker activity for tribo-polymerization at the same mechanical shear condition. These results suggested that the mechanical shear at tribological interfaces could induce the opening of the strained ring structure of α-pinene and pinane, which leads to polymerization of adsorbed molecules at the sliding track. On a stainless steel surface, such polymerization reactions of adsorbed molecules do not occur under typical surface reaction conditions. The mechanical properties and boundary lubrication efficiency of the produced tribo-polymer films are discussed.

Formation of Highly Twisted Ribbons in a Carboxymethylcellulase Gene-Disrupted Strain of a Cellulose-Producing Bacterium

Science.gov (United States)

Sugano, Yasushi; Shoda, Makoto; Sakakibara, Hitoshi; Oiwa, Kazuhiro; Tuzi, Satoru; Imai, Tomoya; Sugiyama, Junji; Takeuchi, Miyuki; Yamauchi, Daisuke

2013-01-01

Cellulases are enzymes that normally digest cellulose; however, some are known to play essential roles in cellulose biosynthesis. Although some endogenous cellulases of plants and cellulose-producing bacteria are reportedly involved in cellulose production, their functions in cellulose production are unknown. In this study, we demonstrated that disruption of the cellulase (carboxymethylcellulase) gene causes irregular packing of de novo-synthesized fibrils in Gluconacetobacter xylinus, a cellulose-producing bacterium. Cellulose production was remarkably reduced and small amounts of particulate material were accumulated in the culture of a cmcax-disrupted G. xylinus strain (F2-2). The particulate material was shown to contain cellulose by both solid-state 13C nuclear magnetic resonance analysis and Fourier transform infrared spectroscopy analysis. Electron microscopy revealed that the cellulose fibrils produced by the F2-2 cells were highly twisted compared with those produced by control cells. This hypertwisting of the fibrils may reduce cellulose synthesis in the F2-2 strains. PMID:23243308

Discovering potential Streptomyces hormone producers by using disruptants of essential biosynthetic genes as indicator strains.

Science.gov (United States)

Thao, Nguyen B; Kitani, Shigeru; Nitta, Hiroko; Tomioka, Toshiya; Nihira, Takuya

2017-10-01

Autoregulators are low-molecular-weight signaling compounds that control the production of many secondary metabolites in actinomycetes and have been referred to as 'Streptomyces hormones'. Here, potential producers of Streptomyces hormones were investigated in 40 Streptomyces and 11 endophytic actinomycetes. Production of γ-butyrolactone-type (IM-2, VB) and butenolide-type (avenolide) Streptomyces hormones was screened using Streptomyces lavendulae FRI-5 (ΔfarX), Streptomyces virginiae (ΔbarX) and Streptomyces avermitilis (Δaco), respectively. In these strains, essential biosynthetic genes for Streptomyces hormones were disrupted, enabling them to respond solely to the externally added hormones. The results showed that 20% of each of the investigated strains produced IM-2 and VB, confirming that γ-butyrolactone-type Streptomyces hormones are the most common in actinomycetes. Unlike the γ-butyrolactone type, butenolide-type Streptomyces hormones have been discovered in recent years, but their distribution has been unclear. Our finding that 24% of actinomycetes (12 of 51 strains) showed avenolide activity revealed for the first time that the butenolide-type Streptomyces hormone is also common in actinomycetes.

An application in cheddar cheese manufacture for a strain of Lactococcus lactis producing a novel broad-spectrum bacteriocin, lacticin 3147.

Science.gov (United States)

Ryan, M P; Rea, M C; Hill, C; Ross, R P

1996-01-01

Lactococcus lactis DPC3147, a strain isolated from an Irish kefir grain, produces a bacteriocin with a broad spectrum of inhibition. The bacteriocin produced is heat stable, particularly at a low pH, and inhibits nisin-producing (Nip+) lactococci. On the basis of the observation that the nisin structural gene (nisA) does not hybridize to DPC3147 genomic DNA, the bacteriocin produced was considered novel and designated lacticin 3147. The genetic determinants which encode lacticin 3147 are contained on a 63-kb plasmid, which was conjugally mobilized to a commercial cheese starter, L. lactis subsp. cremoris DPC4268. The resultant transconjugant, DPC4275, both produces and is immune to lacticin 3147. The ability of lacticin 3147-producing lactococci to perform as cheddar cheese starters was subsequently investigated in cheesemaking trials. Bacteriocin-producing starters (which included the transconjugant strain DPC4275) produced acid at rates similar to those of commercial strains. The level of lacticin 3147 produced in cheese remained constant over 6 months of ripening and correlated with a significant reduction in the levels of nonstarter lactic acid bacteria. Such results suggest that these starters provide a means of controlling developing microflora in ripened fermented products. PMID:8593062

Draft Genome Sequence of Komagataeibacter intermedius Strain AF2, a Producer of Cellulose, Isolated from Kombucha Tea.

Science.gov (United States)

Dos Santos, Renato Augusto Corrêa; Berretta, Andresa Aparecida; Barud, Hernane da Silva; Ribeiro, Sidney José Lima; González-García, Laura Natalia; Zucchi, Tiago Domingues; Goldman, Gustavo H; Riaño-Pachón, Diego M

2015-12-03

Here, we present the draft genome sequence of Komagataeibacter intermedius strain AF2, which was isolated from Kombucha tea and is capable of producing cellulose, although at lower levels compared to another bacterium from the same environment, K. rhaeticus strain AF1. Copyright © 2015 dos Santos et al.

Genomic mutational analysis of the impact of the classical strain improvement program on ß–lactam producing Penicillium chrysogenum

NARCIS (Netherlands)

Salo, O.V.; Ries, M.; Medema, M.H.; Lankhorst, P.P.; Vreeken, R.J.; Bovenberg, R.A.L.; Driessen, A.J.M.

2015-01-01

Background Penicillium chrysogenum is a filamentous fungus that is employed as an industrial producer of ß–lactams. The high ß–lactam titers of current strains is the result of a classical strain improvement program (CSI) starting with a wild-type like strain more than six decades ago. This involved

Strain-specific transmission in an outbreak of ESBL-producing Enterobacteriaceae in the hemato-oncology care unit: a cohort study.

Science.gov (United States)

Uemura, Makiko; Imataki, Osamu; Uchida, Shumpei; Nakayama-Imaohji, Haruyuki; Ohue, Yukiko; Matsuka, Harumi; Mori, Hatsune; Dobashi, Hiroaki; Kuwahara, Tomomi; Kadowaki, Norimitsu

2017-01-05

Extended-spectrum β-lactamase (ESBL)-producing bacteria are resistant to several types of antibiotics excluding carbapenems. A transmissibility of ESBL-producing Enterobacteriaceae would be depending on each bacterial property, however, that has not been elucidated in clinical setting. In this study, we attempted to identify the source of an outbreak of ESBL-producing bacteria in a medical oncology and immunology care unit. An ESBL-producing Enterobacteriaceae (ESBL-E) outbreak observed between July 2012 and August 2012 in Kagawa University Hospital was surveyed using various molecular microbiology techniques. We used Pulsed-field gel electrophoresis (PFGE), PCR-based ESBL gene typing, and direct sequence of ESBL gene as molecular microbiology typing method to distinguish each strain. The typical prevalence of ESBL-E isolation in the unit was 7.0 per month (1.7 per week). The prevalence of ESBL-E isolation during the target research period was 20.0 per month (5.0 per week). In total, 19 isolates (11 K. pneumoniae and 8 E. coli) were obtained from clinical samples, including four control strains (two each of both bacteria), that were physically different from those obtained from other inpatient units in our hospital. Pulsed-field gel electrophoresis (PFGE) for K. pneumoniae (digested by XbaI) produced similar patterns excluding one control strain. PCR classification of the ESBL gene for K. pneumoniae revealed that all strains other than the control strain carried SHV and CTX-M-9. This result was reconfirmed by direct DNA sequencing. Although the outbreak of K. pneumoniae was considered to be "clonal," PFGE and PCR classification of the ESBL genes for E. coli uncovered at least six different "non-clonal" strains possessing individual ESBL gene patterns. According to the result of an antibiogram, the pattern of antimicrobial susceptibility was more variable for K. pneumoniae than for E. coli. Typing by PFGE and ESBL gene PCR analysis is practical for discriminating

A New Bacillus licheniformis Mutant Strain Producing Serine Protease Efficient for Hvdrolvqis of Sov Meal Proteins.

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Kostyleva, E V; Sereda, A S; Velikoretskaya, I A; Nefedova, L I; Sharikov, A Yu; Tsurikova, N V; Lobanov, N S; Semenova, M V; Sinitsyn, A P

2016-07-01

Induced mutagenesis with y-irradiation of the industrial strain Bacillus licheniformis-60 VKM B-2366,D was used to obtain a new highly active producer of an extracellular serine protease, Bacillus licheni- formis7 145. Samples of dry.concentrated preparations of serine protease produced by the original and mutant strains were obtained, and identity of their protein composition was'established. Alkaline serine protease sub- tilisin DY was the main component of the preparations. The biochemical and physicochemical properties of the Protolkheterm-145 enzyme preparation obtained from the mutant strain were studied. It exhibited pro- teolytic activity (1.5 times higher than the preparation from the initial strain) within broad ranges of pH (5- 11) and temperature (30-70'C).-Efficient hydrolysis of extruded soy meal protein at high concentrations (2 to 50%) in-the reaction mixture was.the main advantage of the Protolikheterm 145 preparation. Compared to,. the preparation obtained using the initial strain, the new preparation with increased proteolytic-activity pro- vided for more complete hydrolysis of the main non-nutritious soy,proteins.(glycinin and 0-conglycinin) with the yield of soluble protein increased by 19-28%, which decreased the cost of bioconversion of the protein- aceous material and indicated promise of the new preparation in resource-saving technologies for processing soy meals and cakes.

Annealing Behavior of Nanostructured Aluminum Produced by Cold Rolling to Ultrahigh Strains

DEFF Research Database (Denmark)

Cao, W.Q.; Godfrey, A.; Hansen, Niels

2009-01-01

The isochronal annealing behavior of nanostructured commercial purity aluminum (AA1100 and AA1200) produced by either cold rolling (CR) or accumulative roll bonding (ARB) up to ultrahigh strains of about 99.5 pct reduction in thickness has been studied in the temperature range from 200 degrees C...... to 420 degrees C. Microstructural and texture measurements were made using data from electron backscatter diffraction (EBSD) investigations, and the change in mechanical strength was followed using hardness measurements. A large effect of the rolling strain is observed on recovery at temperatures below...... for analyzing the uniformity of the structural coarsening, based on analysis of the crystallite size distribution with respect to the mode, is described. The analysis demonstrates that annealing leads to locally nonuniform changes in the microstructure, and to a description of the annealing process...

Typing clinical and animal environment Aspergillus fumigatus gliotoxin producer strains isolated from Brazil by PCR-RFLP markers.

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Soleiro, C A; Pena, G A; Cavaglieri, L R; Coelho, I; Keller, L M; Dalcero, A M; Rosa, C A R

2013-12-01

Aspergillus fumigatus, a well-known human and animal pathogen causing aspergillosis, has been historically identified by morphological and microscopic features. However, recent studies have shown that species identification on the basis of morphology alone is problematic. The aim of this work was to confirm the taxonomic state at specie level of a set of clinical (human and animal) and animal environment A. fumigatus strains identified by morphological criteria applying a PCR-RFLP assay by an in silico and in situ analysis with three restriction enzymes. The A. fumigatus gliotoxin-producing ability was also determined. Previous to the in situ PCR-RFLP analysis, an in silico assay with BccI, MspI and Sau3AI restriction enzymes was carried out. After that, these enzymes were used for in situ assay. All A. fumigatus strains isolated from corn silage, human aspergillosis and bovine mastitis and high per cent of the strains isolated from cereals, animal feedstuff and sorghum silage were able to produce high gliotoxin levels. Also, all these strains identified by morphological criteria as A. fumigatus, regardless of its isolation source, had band patterns according to A. fumigatus sensu stricto by PCR-RFLP markers. Aspergillus fumigatus is a well-known human and animal pathogen causing aspergillosis. In this study, clinical (human and animal) and animal environment strains were able to produce high gliotoxin levels and had band profiles according to A. fumigatus sensu stricto by PCR-RFLP markers. The results obtained here suggest that strains involved in human and animal aspergillosis could come from the animal environment in which A. fumigatus is frequently found. Its presence in animal environments could affect animal health and productivity; in addition, there are risks of contamination for rural workers during handling and storage of animal feedstuffs. © 2013 The Society for Applied Microbiology.

Use of Lactobacillus plantarum Strains as a Bio-Control Strategy against Food-Borne Pathogenic Microorganisms

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Arena, Mattia Pia; Silvain, Amandine; Normanno, Giovanni; Grieco, Francesco; Drider, Djamel; Spano, Giuseppe; Fiocco, Daniela

2016-01-01

Lactobacillus plantarum is one of the most versatile species extensively used in the food industry both as microbial starters and probiotic microorganisms. Several L. plantarum strains have been shown to produce different antimicrobial compounds such as organic acids, hydrogen peroxide, diacetyl, and also bacteriocins and antimicrobial peptides, both denoted by a variable spectrum of action. In recent decades, the selection of microbial molecules and/or bacterial strains able to produce antagonistic molecules to be used as antimicrobials and preservatives has been attracting scientific interest, in order to eliminate or reduce chemical additives, because of the growing attention of consumers for healthy and natural food products. The aim of this work was to investigate the antimicrobial activity of several food-isolated L. plantarum strains, analyzed against the pathogenic bacteria Listeria monocytogenes, Salmonella Enteritidis, Escherichia coli O157:H7 and Staphylococcus aureus. Antagonistic activity was assayed by agar spot test and revealed that strain L. plantarum 105 had the strongest ability to contrast the growth of L. monocytogenes, while strains L. plantarum 106 and 107 were the most active microorganisms against E. coli O157:H7. The antimicrobial ability was also screened by well diffusion assay and broth micro-dilution method using cell-free supernatants (CFS) from each Lactobacillus strain. Moreover, the chemical nature of the molecules released in the CFS, and possibly underlying the antagonistic activity, was preliminary characterized by exposure to different constraints such as pH neutralization, heating, catalase, and proteinase treatments. Our data suggest that the ability of L. plantarum cultures to contrast pathogens growth in vitro depends, at least in part, on a pH-lowering effect of supernatants and/or on the presence of organic acids. Cluster analysis was performed in order to group L. plantarum strains according to their antimicrobial effect

Genome Sequence of Lactobacillus saerimneri 30a (Formerly Lactobacillus sp. Strain 30a), a Reference Lactic Acid Bacterium Strain Producing Biogenic Amines

NARCIS (Netherlands)

Romano, Andrea; Trip, Hein; Campbell-Sills, Hugo; Bouchez, Olivier; Sherman, David; Lolkema, Juke S.; Lucas, Patrick M.

2013-01-01

Lactobacillus sp. strain 30a (Lactobacillus saerimneri) produces the biogenic amines histamine, putrescine, and cadaverine by decarboxylating their amino acid precursors. We report its draft genome sequence (1,634,278 bases, 42.6% G+C content) and the principal findings from its annotation, which

KPC and VIM producing Enterobacter cloacae strain from a hospital in northeastern Venezuela.

Science.gov (United States)

Martínez, Dianny; Marcano, Daniel; Rodulfo, Hectorina; Salgado, Nurys; Cuaical, Nirvia; Rodriguez, Lucy; Caña, Luisa; Medina, Belkis; Guzman, Militza; De Donato, Marcos

2015-06-01

An 83-year-old male patient is admitted to the central hospital in Cumana, Venezuela with severe urinary infection, history of hospitalizaions and prolonged antimicrobial treatments. A strain of Enterobacter cloacae was isolated showing resistance to multiple types of antibiotics (only sensitive to gentamicin), with phenotype of serine- and metallo-carbapenemases. Both, bla(VIM-2) and bla(KPC) genes were detected in the isolate. This is the first report of an Enterobacteriaceae species producing both KPC carbapenemase and VIM metallo carbapenemase in Venezuela. This finding has a great clinical and epidemiological impact in the region, because of the feasibility of transferring these genes, through mobile elements to other strains of Enterobacter and to other infection-causing species of bacteria.

Draft genome sequence of a thermostable, alkaliphilic α-amylase and protease producing Bacillus amyloliquefaciens strain KCP2.

Science.gov (United States)

Prajapati, Vimalkumar S; Ray, Sanket; Narayan, Jitendra; Joshi, Chaitanya C; Patel, Kamlesh C; Trivedi, Ujjval B; Patel, R M

2017-12-01

Bacillus amyloliquefaciens strain KCP2 was isolated from municipal food waste samples collected in Vallabh Vidyanagar, Gujarat, India. Strain KCP2 is noteworthy due to its ability to produce a thermostable, alkaliphilic α-amylase and a protease. These enzymes have importance in several industrial processes including bread making, brewing, starch processing, pharmacy, and textile industries. Whole genome sequencing of strain KCP2 showed that the estimated genome size was 3.9 Mb, the G + C content was 46%, and it coded for 4113 genes.

Isolation and identification of biosurfactant-producing strains from the genus Pseudomonas aeruginosa and antibacterial effects of biosurfactant production in vitro

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Salman Ahmady-Asbchin

2013-01-01

Full Text Available Introduction: Biosurfactants are amphiphilic biological compounds produced extracellularly or as part of the cell membranes by a variety of microorganisms. Because of their use in various industries, they are of a particular importance. The aim of this study was to identify a strain of bacteria of the genus Pseudomonas aeruginosa biosurfactant producers. Materials and methods: In this study, different samples of oil, water and soil contaminated with oil were prepared. Hemolytic activity, emulsification activity and measurement of surface tension were used and selected strains were identified by biochemical tests. The nature and effect of antibacterial biosurfactant was evaluated for strain selection.Results: In this study, eighty eight bacterial strains were isolated. Twenty four strains were isolated from the isolated strains with hemolytic activity. Among which, 14 strains have emulsification activity more than 70% and at last four strains reached surface tension to be less than 40 mN/m. Selected strain based on biochemical tests was recognized as a Pseudomonas aeruginosa. The nature of biosurfactant was determined by TLC, and proved to be of glycolipid kind. Therefore, the produced biosurfactant of the selected strain had antibacterial activity against six bacterial infectious. Sensitive bacteria to the effects of biosurfactant extract of Pseudomonas aeruginosa83, was Staphylococcus aureus and the most resistant bacteria to these extract, was the Proteus mirabilis. The results of MIC, MBC showed that MIC of the extract in concentration of 63 and 125 mg/ml on Escherichia coli, Staphylococcus epidermidis and Staphylococcus aureus respectively. Also, the MBC were extract in concentration of 63 and 125mg/ml on Staphylococcus epidermidis and Staphylococcus aureus respectively.Discussion and conclusion: Pseudomonas aeruginosa had high potential in reducing the surface tension and biosurfactant extracted had high antibacterial effects. Therefore, it

Screening and characterization of lactic acid bacterial strains that produce fermented milk and reduce cholesterol levels

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Xuefang Guan

Full Text Available ABSTRACT Objective To screen for and characterize lactic acid bacteria strains with the ability to produce fermented milk and reduce cholesterol levels. Methods The strains were isolated from traditional fermented milk in China. In vitro and in vivo evaluation of cholesterol-reduction were used to identify and verify strains of interest. Characteristics were analyzed using spectrophotometry and plate counting assays. Results The isolate HLX37 consistently produced fermented milk with strong cholesterol-reducing properties was identified as Lactobacillus plantarum (accession number: KR105940 and was thus selected for further study. The cholesterol reduction by strain HLX37 was 45.84%. The isolates were acid-tolerant at pH 2.5 and bile-tolerant at 0.5% (w/v in simulated gastric juice (pH 2.5 for 2 h and in simulated intestinal fluid (pH 8.0 for 3 h. The auto-aggregation rate increased to 87.74% after 24 h, while the co-aggregation with Escherichia coli DH5 was 27.76%. Strain HLX37 was intrinsically resistant to antibiotics such as penicillin, tobramycin, kanamycin, streptomycin, vancomycin and amikacin. Compared with rats in the model hyperlipidemia group, the total cholesterol content in the serum and the liver as well as the atherogenic index of rats in the viable fermented milk group significantly decreased by 23.33%, 32.37% and 40.23%, respectively. Fewer fat vacuoles and other lesions in liver tissue were present in both the inactivated and viable fermented milk groups compared to the model group. Conclusion These studies indicate that strain HLX37 of L. plantarum demonstrates probiotic potential, potential for use as a candidate for commercial use for promoting health.

Insights from the genome of a high alkaline cellulase producing Aspergillus fumigatus strain obtained from Peruvian Amazon rainforest.

Science.gov (United States)

Paul, Sujay; Zhang, Angel; Ludeña, Yvette; Villena, Gretty K; Yu, Fengan; Sherman, David H; Gutiérrez-Correa, Marcel

2017-06-10

Here, we report the complete genome sequence of a high alkaline cellulase producing Aspergillus fumigatus strain LMB-35Aa isolated from soil of Peruvian Amazon rainforest. The genome is ∼27.5mb in size, comprises of 228 scaffolds with an average GC content of 50%, and is predicted to contain a total of 8660 protein-coding genes. Of which, 6156 are with known function; it codes for 607 putative CAZymes families potentially involved in carbohydrate metabolism. Several important cellulose degrading genes, such as endoglucanase A, endoglucanase B, endoglucanase D and beta-glucosidase, are also identified. The genome of A. fumigatus strain LMB-35Aa represents the first whole sequenced genome of non-clinical, high cellulase producing A. fumigatus strain isolated from forest soil. Copyright © 2017 Elsevier B.V. All rights reserved.

Screening of bacterial strains for pectinolytic activity: characterization of the polygalacturonase produced by Bacillus sp

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Soares Márcia M.C.N.

1999-01-01

Full Text Available One hundred sixty eight bacterial strains, isolated from soil and samples of vegetable in decomposition, were screened for the use of citrus pectin as the sole carbon source. 102 were positive for pectinase depolymerization in assay plates as evidenced by clear hydrolization halos. Among them, 30% presented considerable pectinolytic activity. The cultivation of these strains by submerged and semi-solid fermentation for polygalacturonase production indicated that five strains of Bacillus sp produced high quantities of the enzyme. The physico-chemical characteristics, such as optimum pH of 6.0 - 7.0, optimum temperatures between 45oC and 55oC, stability at temperatures above 40oC and in neutral and alkaline pH, were determined.

Isolation and characterization of large spectrum and multiple bacteriocin-producing Enterococcus faecium strain from raw bovine milk.

Science.gov (United States)

Gaaloul, N; ben Braiek, O; Hani, K; Volski, A; Chikindas, M L; Ghrairi, T

2015-02-01

To assess the antimicrobial properties of lactic acid bacteria from Tunisian raw bovine milk. A bacteriocin-producing Enterococcus faecium strain was isolated from raw cow milk with activity against Gram-positive and Gram-negative bacteria. Antimicrobial substances produced by this strain were sensitive to proteolytic enzymes and were thermostable and resistant to a broad range of pH (2-10). Mode of action of antimicrobial substances was determined as bactericidal. Maximum activity was reached at the end of the exponential growth phase when checked against Listeria ivanovii BUG 496 (2366.62 AU ml(-1)). However, maximum antimicrobial activity against Pseudomonas aeruginosa 28753 was recorded at the beginning of the exponential growth phase. Enterococcus faecium GGN7 was characterized as free from virulence factors and was susceptible to tested antibiotics. PCR analysis of the micro-organism's genome revealed the presence of genes coding for enterocins A and B. Mass spectrometry analysis of RP-HPLC active fractions showed molecular masses corresponding to enterocins A (4835.77 Da) and B (5471.56 Da), and a peptide with a molecular mass of 3215.5 Da active only against Gram-negative indicator strains. The latter was unique in the databases. Enterococcus faecium GGN7 produces three bacteriocins with different inhibitory spectra. Based on its antimicrobial properties and safety, Ent. faecium GGN7 is potentially useful for food biopreservation. The results suggest the bacteriocins from GGN7 strain could be useful for food biopreservation. © 2014 The Society for Applied Microbiology.

Quorum sensing signaling molecules produced by reference and emerging soft-rot bacteria (Dickeya and Pectobacterium spp..

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Alexandre Crépin

Full Text Available Several small diffusible molecules are involved in bacterial quorum sensing and virulence. The production of autoinducers-1 and -2, quinolone, indole and γ-amino butyrate signaling molecules was investigated in a set of soft-rot bacteria belonging to six Dickeya or Pectobacterium species including recent or emerging potato isolates.Using bacterial biosensors, immunoassay, and chromatographic analysis, we showed that soft-rot bacteria have the common ability to produce transiently during their exponential phase of growth the N-3-oxo-hexanoyl- or the N-3-oxo-octanoyl-l-homoserine lactones and a molecule of the autoinducer-2 family. Dickeya spp. produced in addition the indole-3-acetic acid in tryptophan-rich conditions. All these signaling molecules have been identified for the first time in the novel Dickeya solani species. In contrast, quinolone and γ-amino butyrate signals were not identified and the corresponding synthases are not present in the available genomes of soft-rot bacteria. To determine if the variations of signal production according to growth phase could result from expression modifications of the corresponding synthase gene, the respective mRNA levels were estimated by reverse transcriptase-PCR. While the N-acyl-homoserine lactone production is systematically correlated to the synthase expression, that of the autoinducer-2 follows the expression of an enzyme upstream in the activated methyl cycle and providing its precursor, rather than the expression of its own synthase.Despite sharing the S-adenosylmethionine precursor, no strong link was detected between the production kinetics or metabolic pathways of autoinducers-1 and -2. In contrast, the signaling pathway of autoinducer-2 seems to be switched off by the indole-3-acetic acid pathway under tryptophan control. It therefore appears that the two genera of soft-rot bacteria have similarities but also differences in the mechanisms of communication via the diffusible molecules

Quorum Sensing Signaling Molecules Produced by Reference and Emerging Soft-Rot Bacteria (Dickeya and Pectobacterium spp.)

Science.gov (United States)

Crépin, Alexandre; Barbey, Corinne; Beury-Cirou, Amélie; Hélias, Valérie; Taupin, Laure; Reverchon, Sylvie; Nasser, William; Faure, Denis; Dufour, Alain; Orange, Nicole; Feuilloley, Marc; Heurlier, Karin; Burini, Jean-François; Latour, Xavier

2012-01-01

Background Several small diffusible molecules are involved in bacterial quorum sensing and virulence. The production of autoinducers-1 and -2, quinolone, indole and γ-amino butyrate signaling molecules was investigated in a set of soft-rot bacteria belonging to six Dickeya or Pectobacterium species including recent or emerging potato isolates. Methodology/Principal Findings Using bacterial biosensors, immunoassay, and chromatographic analysis, we showed that soft-rot bacteria have the common ability to produce transiently during their exponential phase of growth the N-3-oxo-hexanoyl- or the N-3-oxo-octanoyl-l-homoserine lactones and a molecule of the autoinducer-2 family. Dickeya spp. produced in addition the indole-3-acetic acid in tryptophan-rich conditions. All these signaling molecules have been identified for the first time in the novel Dickeya solani species. In contrast, quinolone and γ-amino butyrate signals were not identified and the corresponding synthases are not present in the available genomes of soft-rot bacteria. To determine if the variations of signal production according to growth phase could result from expression modifications of the corresponding synthase gene, the respective mRNA levels were estimated by reverse transcriptase-PCR. While the N-acyl-homoserine lactone production is systematically correlated to the synthase expression, that of the autoinducer-2 follows the expression of an enzyme upstream in the activated methyl cycle and providing its precursor, rather than the expression of its own synthase. Conclusions/Significance Despite sharing the S-adenosylmethionine precursor, no strong link was detected between the production kinetics or metabolic pathways of autoinducers-1 and -2. In contrast, the signaling pathway of autoinducer-2 seems to be switched off by the indole-3-acetic acid pathway under tryptophan control. It therefore appears that the two genera of soft-rot bacteria have similarities but also differences in the

Induction of bacteriocin production by coculture is widespread among plantaricin-producing Lactobacillus plantarum strains with different regulatory operons.

Science.gov (United States)

Maldonado-Barragán, Antonio; Caballero-Guerrero, Belén; Lucena-Padrós, Helena; Ruiz-Barba, José Luis

2013-02-01

We describe the bacteriocin-production phenotype in a group of eight singular bacteriocinogenic Lactobacillus plantarum strains with three distinct genotypes regarding the plantaricin locus. Genotyping of these strains revealed the existence of two different plantaricin-production regulatory operons, plNC8-plNC8HK-plnD or plnABCD, involving three-component systems controlled each of them by a specific autoinducer peptide (AIP), i.e. PLNC8IF or PlnA. While all of the strains produced antimicrobial activity when growing on solid medium, most of them halted this production when cultured in broth, thus reflecting the functionality of regulatory mechanisms. Antimicrobial activity in broth cultures was re-established or enhanced when the specific AIP was added to the culture or by coculturing with specific bacterial strains. The latter trait appeared to be widespread in bacteriocinogenic L. plantarum strains independently of the regulatory system used to regulate bacteriocin production or the specific bacteriocins produced. The induction spectrum through coculture, i.e. the pattern of bacterial strains able to induce bacteriocin production, was characteristic of each individual L. plantarum strain. Also, the ability of some bacteria to induce bacteriocin production in L. plantarum by coculture appeared to be strain specific. The fact that induction of bacteriocin production by coculturing appeared to be a common feature in L. plantarum can be exploited accordingly to enhance the viability of this species in food and feed fermentations, as well as to contribute to probiotic functionality when colonising the gastrointestinal tract. Copyright © 2012 Elsevier Ltd. All rights reserved.

Characterisation of inhibitory substances produced by two Pseudoalteromonas species and the cyanobacterial strain Flo1

OpenAIRE

Rau, Jan Erik

2011-01-01

In the present study the inhibitory substances of P. aurantia NCIMB 2052T and P. citrea NCIMB 1889T were investigated with respect to their substantial and functional nature, their inhibitory potential, their stability against various treatments as well as the growth phases and incubation conditions when the substances are produced. In addition, an inhibitory substance produced by strain Flo1 was examined regarding its structure, function, and inhibitory potential. Furthermore, its taxonomic ...

Degradation of Bacterial Quorum Sensing Signaling Molecules by the Microscopic Yeast Trichosporon loubieri Isolated from Tropical Wetland Waters

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Cheng-Siang Wong

2013-09-01

Full Text Available Proteobacteria produce N-acylhomoserine lactones as signaling molecules, which will bind to their cognate receptor and activate quorum sensing-mediated phenotypes in a population-dependent manner. Although quorum sensing signaling molecules can be degraded by bacteria or fungi, there is no reported work on the degradation of such molecules by basidiomycetous yeast. By using a minimal growth medium containing N-3-oxohexanoylhomoserine lactone as the sole source of carbon, a wetland water sample from Malaysia was enriched for microbial strains that can degrade N-acylhomoserine lactones, and consequently, a basidiomycetous yeast strain WW1C was isolated. Morphological phenotype and molecular analyses confirmed that WW1C was a strain of Trichosporon loubieri. We showed that WW1C degraded AHLs with N-acyl side chains ranging from 4 to 10 carbons in length, with or without oxo group substitutions at the C3 position. Re-lactonisation bioassays revealed that WW1C degraded AHLs via a lactonase activity. To the best of our knowledge, this is the first report of degradation of N-acyl-homoserine lactones and utilization of N-3-oxohexanoylhomoserine as carbon and nitrogen source for growth by basidiomycetous yeast from tropical wetland water; and the degradation of bacterial quorum sensing molecules by an eukaryotic yeast.

The hydrolytic enzymes produced by fungi strains isolated from the sand and soil of recreational areas

Science.gov (United States)

Kurnatowski, Piotr; Wójcik, Anna; Błaszkowska, Joanna; Góralska, Katarzyna

2016-10-01

The pathogenicity of fungi depends on, inter alia, the secretion of hydrolytic enzymes. The aim of this study was to determine the enzymatic activity of yeasts and yeast-like fungi isolated from children’s recreation areas, and compare the results with literature data of strains obtained from patients with mycoses. The enzymatic activity of 96 strains was assessed using an API ZYM kit (bioMerieux, France) and their biotypes were established. The fungal species were found to produce from 16 to 19 hydrolases: the most active were: leucine arylamidase (e5), acid phosphatase (e10), alkaline phosphatase (e1), naphthol-AS-BI-phosphohydrolase (e11), esterase – C4 (e2), β-galac - tosidase (e13) and β-glucosidase (e16). In addition, 13 biotypes characteristic of particular species of fungi were defined. Most strains could be categorized as biotypes C2 – 39.5% and A – 26%. The examined fungal strains isolated from recreational areas have selected biochemical characteristics i.e. production of hydrolases, which demonstrate their pathogenicity. They produce a number of enzymes which are also present in strains isolated from patients with mycoses, including: leucine arylamidase (e5), acid phosphatase (e10), naphthol-AS-BI-phosphohydrolase (e11) and alkaline phosphatase (e1). The biotypes identified in the course of this study (A, B3, B4, C1, C6 and D3) have been also reported in cases of fungal infection. Therefore, the fungi present in the sand and soil of recreational have pathogenic properties and are possible factors of fungal infection among children.

Cadophora malorum Cs-8-1 as a new fungal strain producing gibberellins isolated from Calystegia soldanella.

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You, Young-Hyun; Yoon, Hyeokjun; Kang, Sang-Mo; Woo, Ju-Ri; Choo, Yeon-Sik; Lee, In-Jung; Shin, Jae-Ho; Kim, Jong-Guk

2013-07-01

Fourteen endophytic fungi with different colony morphologies were isolated from the roots of Calystegia soldanella. Endophytic fungi isolated from C. soldanella were identified by internal transcribed spacer (ITS) region. To verify plant growth promotion (PGP), culture filtrates of isolated endophytic fungi were treated in Waito-c rice (WR) and C. soldanella seedlings. Culture filtrates of Cs-8-1 fungal strain had advanced PGP activity. The presence of physiologically bioactive gibberellins (GA) GA(1) (1.213 ng ml(-1)), GA(3) (1.292 ng ml(-1)), GA(4) (3.6 ng ml(-1)), GA(7) (1.328 ng ml(-1)), other inactive GA(9) (0.796 ng ml(-1)) and GA(12) (0.417 ng ml(-1)), GA(20) (0.302 ng ml(-1)), GA(24) (1.351 ng ml(-1)), GA(34) (0.076 ng ml(-1)), and GA(53) (0.051 ng ml(-1)) in culture filtrates of Cs-8-1 fungal strain was detected. The Cs-8-1 fungal strain was confirmed as a producer of GAs. Molecular analysis of sequences showed high similarity of 99% to Cadophora malorum. Consequentially, the Cs-8-1 fungal strain was identified as a new C. malorum producing GAs. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Screening and characterization of lactic acid bacterial strains that produce fermented milk and reduce cholesterol levels.

Science.gov (United States)

Guan, Xuefang; Xu, Qingxian; Zheng, Yi; Qian, Lei; Lin, Bin

To screen for and characterize lactic acid bacteria strains with the ability to produce fermented milk and reduce cholesterol levels. The strains were isolated from traditional fermented milk in China. In vitro and in vivo evaluation of cholesterol-reduction were used to identify and verify strains of interest. Characteristics were analyzed using spectrophotometry and plate counting assays. The isolate HLX37 consistently produced fermented milk with strong cholesterol-reducing properties was identified as Lactobacillus plantarum (accession number: KR105940) and was thus selected for further study. The cholesterol reduction by strain HLX37 was 45.84%. The isolates were acid-tolerant at pH 2.5 and bile-tolerant at 0.5% (w/v) in simulated gastric juice (pH 2.5) for 2h and in simulated intestinal fluid (pH 8.0) for 3h. The auto-aggregation rate increased to 87.74% after 24h, while the co-aggregation with Escherichia coli DH5 was 27.76%. Strain HLX37 was intrinsically resistant to antibiotics such as penicillin, tobramycin, kanamycin, streptomycin, vancomycin and amikacin. Compared with rats in the model hyperlipidemia group, the total cholesterol content in the serum and the liver as well as the atherogenic index of rats in the viable fermented milk group significantly decreased by 23.33%, 32.37% and 40.23%, respectively. Fewer fat vacuoles and other lesions in liver tissue were present in both the inactivated and viable fermented milk groups compared to the model group. These studies indicate that strain HLX37 of L. plantarum demonstrates probiotic potential, potential for use as a candidate for commercial use for promoting health. Copyright © 2017 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

Multiply excited molecules produced by photon and electron interactions

International Nuclear Information System (INIS)

Odagiri, T.; Kouchi, N.

2006-01-01

The photon and electron interactions with molecules resulting in the formation of multiply excited molecules and the subsequent decay are subjects of great interest because the independent electron model and Born-Oppenheimer approximation are much less reliable for the multiply excited states of molecules than for the ground and lower excited electronic states. We have three methods to observe and investigate multiply excited molecules: 1) Measurements of the cross sections for the emission of fluorescence emitted by neutral fragments in the photoexcitation of molecules as a function of incident photon energy [1-3], 2) Measurements of the electron energy-loss spectra tagged with the fluorescence photons emitted by neutral fragments [4], 3) Measurements of the cross sections for generating a pair of photons in absorption of a single photon by a molecule as a function of incident photon energy [5-7]. Multiply excited states degenerate with ionization continua, which make a large contribution in the cross section curve involving ionization processes. The key point of our methods is hence that we measure cross sections free from ionization. The feature of multiply excited states is noticeable in such a cross section curve. Recently we have measured: i) the cross sections for the emission of the Lyman- fluorescence in the photoexcitation of CH 4 as a function of incident photon energy in the range 18-51 eV, ii) the electron energy-loss spectrum of CH 4 tagged with the Lyman-photons at 80 eV incident electron energy and 10 electron scattering angle in the range of the energy loss 20-45 eV, in order to understand the formation and decay of the doubly excited methane in photon and electron interactions. [8] The results are summarized in this paper and the simultaneous excitation of two electrons by electron interaction is compared with that by photon interaction in terms of the oscillator strength. (authors)

Staphylococcus haemolyticus as a potential producer of biosurfactants with antimicrobial, anti-adhesive and synergistic properties.

Science.gov (United States)

Rossi, C C; Santos-Gandelman, J F; Barros, E M; Alvarez, V M; Laport, M S; Giambiagi-deMarval, M

2016-09-01

Staphylococcus haemolyticus is an opportunistic human pathogen that usually gains entry into the host tissue in association with medical device contamination. Biofilm formation is a key factor for the establishment of this bacterium and its arrangement and dynamics can be influenced by the synthesis of biosurfactants. Biosurfactants are structurally diverse amphiphilic molecules with versatile biotechnological applications, but information on their production by staphylococci is still scarce. In this work, two Staph. haemolyticus strains, showing high potential for biosurfactant production - as observed by four complementary methods - were investigated. Biosurfactant extracts were produced and studied for their capacity to inhibit the growth and biofilm formation by other bacterial human pathogens. The biosurfactant produced by the one of the strains inhibited the growth of most bacteria tested and subinhibitory concentrations of the biosurfactant were able to decrease biofilm formation and showed synergistic effects with tetracycline. Because these results were also positive when the biosurfactants were tested against the producing strains, it is likely that biosurfactant production by Staph. haemolyticus may be an unexplored virulence factor, important for competition and biofilm formation by the bacterium, in addition to the biotechnological potential. This work is the first to show the production of biosurfactants by Staphylococcus haemolyticus strains. Extracts showed antimicrobial, anti-adhesive and synergistic properties against a variety of relevant human pathogens, including the producing strains. In addition to the biotechnological potential, biosurfactants produced by Staph. haemolyticus are potentially undescribed virulence determinants in their producing strains. © 2016 The Society for Applied Microbiology.

Antagonistic effect of Lactobacillus strains against gas-producing coliforms isolated from colicky infants

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Oggero Roberto

2011-06-01

Full Text Available Abstract Background Infantile colic is a common disturb within the first 3 months of life, nevertheless the pathogenesis is incompletely understood and treatment remains an open issue. Intestinal gas production is thought to be one of the causes of abdominal discomfort in infants suffering from colic. However, data about the role of the amount of gas produced by infants' colonic microbiota and the correlation with the onset of colic symptoms are scanty. The benefit of supplementation with lactobacilli been recently reported but the mechanisms by which they exert their effects have not yet been fully defined. This study was performed to evaluate the interaction between Lactobacillus spp. strains and gas-forming coliforms isolated from stools of colicky infants. Results Strains of coliforms were isolated from stools of 45 colicky and 42 control breastfed infants in McConkey Agar and identified using PCR with species-specific primers, and the BBL™ Enterotube™ II system for Enterobacteriaceae. Gas-forming capability of coliforms was assessed in liquid cultures containing lactose as sole carbon source. The average count of total coliforms in colicky infants was significantly higher than controls: 5.98 (2.00-8.76 log10 vs 3.90 (2.50-7.10 CFU/g of faeces (p = 0.015. The following strains were identified: Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, Enterobacter aerogenes, Enterobacter cloacae and Enterococcus faecalis. Then, 27 Lactobacillus strains were tested for their antagonistic effect against coliforms both by halo-forming method and in liquid co-cultures. Lactobacillus delbrueckii subsp.delbrueckii DSM 20074 and L. plantarum MB 456 were able to inhibit all coliforms strains (halo-forming method, also in liquid co-cultures, thus demonstrating an antagonistic activity. Conclusions This study shows that two out of 27 strains of Lactobacillus examined possess an antimicrobial effect against six species of gas-forming coliforms

Antagonistic effect of Lactobacillus strains against gas-producing coliforms isolated from colicky infants.

Science.gov (United States)

Savino, Francesco; Cordisco, Lisa; Tarasco, Valentina; Locatelli, Emanuela; Di Gioia, Diana; Oggero, Roberto; Matteuzzi, Diego

2011-06-30

Infantile colic is a common disturb within the first 3 months of life, nevertheless the pathogenesis is incompletely understood and treatment remains an open issue. Intestinal gas production is thought to be one of the causes of abdominal discomfort in infants suffering from colic. However, data about the role of the amount of gas produced by infants' colonic microbiota and the correlation with the onset of colic symptoms are scanty. The benefit of supplementation with lactobacilli been recently reported but the mechanisms by which they exert their effects have not yet been fully defined. This study was performed to evaluate the interaction between Lactobacillus spp. strains and gas-forming coliforms isolated from stools of colicky infants. Strains of coliforms were isolated from stools of 45 colicky and 42 control breastfed infants in McConkey Agar and identified using PCR with species-specific primers, and the BBL™ Enterotube™ II system for Enterobacteriaceae. Gas-forming capability of coliforms was assessed in liquid cultures containing lactose as sole carbon source. The average count of total coliforms in colicky infants was significantly higher than controls: 5.98 (2.00-8.76) log10 vs 3.90 (2.50-7.10) CFU/g of faeces (p = 0.015). The following strains were identified: Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, Enterobacter aerogenes, Enterobacter cloacae and Enterococcus faecalis. Then, 27 Lactobacillus strains were tested for their antagonistic effect against coliforms both by halo-forming method and in liquid co-cultures. Lactobacillus delbrueckii subsp. delbrueckii DSM 20074 and L. plantarum MB 456 were able to inhibit all coliforms strains (halo-forming method), also in liquid co-cultures, thus demonstrating an antagonistic activity. This study shows that two out of 27 strains of Lactobacillus examined possess an antimicrobial effect against six species of gas-forming coliforms isolated from colicky infants. Our findings may stimulate

Description of two Enterococcus strains isolated from traditional Peruvian artisanal-produced cheeses with a bacteriocin-like inhibitory activity

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Aguilar Galvez A.

2009-01-01

Full Text Available The aim of this work was to isolate and to characterize strains of lactic acid bacteria (LAB with bacteriocin-like inhibitory activity from 27 traditional cheeses artisanal-produced obtained from different Peruvian regions. Twenty Gram+ and catalasenegative strains among 2,277 isolates exhibited bacteriocin-like inhibitory activity against Listeria monocytogenes CWBIB2232 as target strain. No change in inhibitory activity was observed after organic acid neutralization and treatment with catalase of the cell-free supernatant (CFS. The proteinic nature of the antimicrobial activity was confirmed for the twenty LAB strains by proteolytic digestion of the CFS. Two strains, CWBI-B1431 and CWBI-B1430, with the best antimicrobial activity were selected for further researches. These strains were taxonomically identified by phenotypic and genotypic analyses as Enterococcus mundtii (CWBI-B1431 and Enterococcus faecium (CWBI-B1430. The two strains were sensitive to vancomycin (MIC 2 μg.ml-1 and showed absence of haemolysis.

The screening of bacillus subtilis strain with high-produced antimicrobial substance using N+ ion implantation

International Nuclear Information System (INIS)

Shen Juan; Bie Xiaomei; Lu Zhaoxin; Lu Fengxia; Zhu Xiaoyu

2006-01-01

N + ion implantation was used to obtain higher-yield antimicrobial substance. Bacillus subtilis fmbJ was mutated by 25 keV N + ion implantation with the dose of 50 x 2.6 x 10 13 , 80 x 2.6 x 10 13 , 100 x 2.6 x 10 13 , 120 x 2.6 x 10 13 and 150 x 2.6 x 10 13 N + /m 2 . Results showed that the optimal N + ion dose was 50 x 2.6 x 10 13 N + /m 2 , and a strain of high-yield antimicrobials was obtained and named as Bacillus subtilis fmbJ224. Its antimicrobial substance yield was increased by 96% than the initial. The fermentation characteristic of the strain was studied, and the mode of producing antimicrobial substance for the selected strain was arrearage synthesis type. (authors)

Detection of Quorum Sensing Activity in the Multidrug-Resistant Clinical Isolate Pseudomonas aeruginosa Strain GB11

OpenAIRE

Huey Jia Cheng; Robson Ee; Yuet Meng Cheong; Wen-Si Tan; Wai-Fong Yin; Kok-Gan Chan

2014-01-01

A multidrug-resistant clinical bacteria strain GB11 was isolated from a wound swab on the leg of a patient. Identity of stain GB11 as Pseudomonas aeruginosa was validated by using matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS). Detection of the production of signaling molecules, N-acylhomoserine lactones (AHLs), was conducted using three different bacterial biosensors. A total of four different AHLs were found to be produced by strain GB11, namely...

Screening of biosurfactant-producing Bacillus strains using glycerol from the biodiesel synthesis as main carbon source.

Science.gov (United States)

Sousa, M; Melo, V M M; Rodrigues, S; Sant'ana, H B; Gonçalves, L R B

2012-08-01

Glycerol, a co-product of biodiesel production, was evaluated as carbon source for biosurfactant production. For this reason, seven non-pathogenic biosurfactant-producing Bacillus strains, isolated from the tank of chlorination at the Wastewater Treatment Plant at Federal University of Ceara, were screened. The production of biosurfactant was verified by determining the surface tension value, as well as the emulsifying capacity of the free-cell broth against soy oil, kerosene and N-hexadecane. Best results were achieved when using LAMI005 and LAMI009 strains, whose biosurfactant reduced the surface tension of the broth to 28.8 ± 0.0 and 27.1 ± 0.1 mN m(-1), respectively. Additionally, at 72 h of cultivation, 441.06 and 267.56 mg L(-1) of surfactin were produced by LAMI005 and LAMI009, respectively. The biosurfactants were capable of forming stable emulsions with various hydrocarbons, such as soy oil and kerosene. Analyses carried out with high performance liquid chromatography (HPLC) showed that the biosurfactant produced by Bacillus subtilis LAMI009 and LAMI005 was compatible with the commercially available surfactin standard. The values of minimum surface tension and the CMC of the produced biosurfactant indicated that it is feasible to produce biosurfactants from a residual and renewable and low-cost carbon source, such as glycerol.

Effect of cerulenin on fatty acid composition and gene expression pattern of DHA-producing strain Colwellia psychrerythraea strain 34H.

Science.gov (United States)

Wan, Xia; Peng, Yun-Feng; Zhou, Xue-Rong; Gong, Yang-Min; Huang, Feng-Hong; Moncalián, Gabriel

2016-02-06

Colwellia psychrerythraea 34H is a psychrophilic bacterium able to produce docosahexaenoic acid (DHA). Polyketide synthase pathway is assumed to be responsible for DHA production in marine bacteria. Five pfa genes from strain 34H were confirmed to be responsible for DHA formation by heterogeneous expression in Escherichia coli. The complexity of fatty acid profile of this strain was revealed by GC and GC-MS. Treatment of cells with cerulenin resulted in significantly reduced level of C16 monounsaturated fatty acid (C16:1(Δ9t), C16:1(Δ7)). In contrast, the amount of saturated fatty acids (C10:0, C12:0, C14:0), hydroxyl fatty acids (3-OH C10:0 and 3-OH C12:0), as well as C20:4ω3, C20:5ω3 and C22:6ω3 were increased. RNA sequencing (RNA-Seq) revealed the altered gene expression pattern when C. psychrerythraea cells were treated with cerulenin. Genes involved in polyketide synthase pathway and fatty acid biosynthesis pathway were not obviously affected by cerulenin treatment. In contrast, several genes involved in fatty acid degradation or β-oxidation pathway were dramatically reduced at the transcriptional level. Genes responsible for DHA formation in C. psychrerythraea was first cloned and characterized. We revealed the complexity of fatty acid profile in this DHA-producing strain. Cerulenin could substantially change the fatty acid composition by affecting the fatty acid degradation at transcriptional level. Acyl-CoA dehydrogenase gene family involved in the first step of β-oxidation pathway may be important to the selectivity of degraded fatty acids. In addition, inhibition of FabB protein by cerulenin may lead to the accumulation of malonyl-CoA, which is the substrate for DHA formation.

Strain-Level Discrimination of Shiga Toxin-Producing Escherichia coli in Spinach Using Metagenomic Sequencing.

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Susan R Leonard

Full Text Available Consumption of fresh bagged spinach contaminated with Shiga toxin-producing Escherichia coli (STEC has led to severe illness and death; however current culture-based methods to detect foodborne STEC are time consuming. Since not all STEC strains are considered pathogenic to humans, it is crucial to incorporate virulence characterization of STEC in the detection method. In this study, we assess the comprehensiveness of utilizing a shotgun metagenomics approach for detection and strain-level identification by spiking spinach with a variety of genomically disparate STEC strains at a low contamination level of 0.1 CFU/g. Molecular serotyping, virulence gene characterization, microbial community analysis, and E. coli core gene single nucleotide polymorphism (SNP analysis were performed on metagenomic sequence data from enriched samples. It was determined from bacterial community analysis that E. coli, which was classified at the phylogroup level, was a major component of the population in most samples. However, in over half the samples, molecular serotyping revealed the presence of indigenous E. coli which also contributed to the percent abundance of E. coli. Despite the presence of additional E. coli strains, the serotype and virulence genes of the spiked STEC, including correct Shiga toxin subtype, were detected in 94% of the samples with a total number of reads per sample averaging 2.4 million. Variation in STEC abundance and/or detection was observed in replicate spiked samples, indicating an effect from the indigenous microbiota during enrichment. SNP analysis of the metagenomic data correctly placed the spiked STEC in a phylogeny of related strains in cases where the indigenous E. coli did not predominate in the enriched sample. Also, for these samples, our analysis demonstrates that strain-level phylogenetic resolution is possible using shotgun metagenomic data for determining the genomic relatedness of a contaminating STEC strain to other

Isolation and characterization of biosurfactant producing bacteria from Persian Gulf (Bushehr provenance).

Science.gov (United States)

Hassanshahian, Mehdi

2014-09-15

Biosurfactants are surface active materials that are produced by some microorganisms. These molecules increase biodegradation of insoluble pollutants. In this study sediments and seawater samples were collected from the coastline of Bushehr provenance in the Persian Gulf and their biosurfactant producing bacteria were isolated. Biosurfactant producing bacteria were isolated by using an enrichment method in Bushnell-Hass medium with diesel oil as the sole carbon source. Five screening tests were used for selection of Biosurfactant producing bacteria: hemolysis in blood agar, oil spreading, drop collapse, emulsification activity and Bacterial Adhesion to Hydrocarbon test (BATH). These bacteria were identified using biochemical and molecular methods. Eighty different colonies were isolated from the collected samples. The most biosurfactant producing isolates related to petrochemical plants of Khark Island. Fourteen biosurfactant producing bacteria were selected between these isolates and 7 isolates were screened as these were predominant producers that belong to Shewanella alga, Shewanella upenei, Vibrio furnissii, Gallaecimonas pentaromativorans, Brevibacterium epidermidis, Psychrobacter namhaensis and Pseudomonas fluorescens. The largest clear zone diameters in oil spreading were observed for G. pentaromativorans strain O15. Also, this strain has the best emulsification activity and reduction of surface tension, suggesting it is the best of thee isolated strains. The results of this study confirmed that there is high diversity of biosurfactant producing bacteria in marine ecosystem of Iran and by application of these bacteria in petrochemical waste water environmental problems can be assisted. Copyright © 2014 Elsevier Ltd. All rights reserved.

Identification and characterization of an N-acylhomoserine lactone-dependent quorum-sensing system in Pseudomonas putida strain IsoF

DEFF Research Database (Denmark)

Steidle, A.; Allesen-Holm, M.; Riedel, K.

2002-01-01

Recent reports have shown that several strains of Pseudomonas putida produce N-acylhomoserine lactones (AHLs). These signal molecules enable bacteria to coordinately express certain phenotypic traits in a density-dependent manner in a process referred to as quorum sensing. In this study we have...

Prevalence and clonal relationship of ESBL-producing Salmonella strains from humans and poultry in northeastern Algeria.

Science.gov (United States)

Djeffal, Samia; Bakour, Sofiane; Mamache, Bakir; Elgroud, Rachid; Agabou, Amir; Chabou, Selma; Hireche, Sana; Bouaziz, Omar; Rahal, Kheira; Rolain, Jean-Marc

2017-05-15

The aims of this study were to investigate Salmonella contamination in broiler chicken farms and slaughterhouses, to assess the antibiotic resistance profile in avian and human Salmonella isolates, and to evaluate the relationship between avian and human Extended Spectrum β-Lactamase (ESBL)-producing isolates. Salmonella was screened in different sample matrices collected at thirty-two chicken farms and five slaughterhouses. The human isolates were recovered from clinical specimens at the University Teaching Hospital of Constantine (UTH). All suspected colonies were confirmed by MALDI-TOF (Matrix Assisted Laser Desorption Ionization Time OF light) and serotyped. Susceptibility testing against 13 antibiotics including, amoxicillin/clavulanic acid, ticarcillin, cefoxitin, cefotaxime, aztreonam, imipenem, ertapenem, gentamicin, amikacin, ciprofloxacin, colistin, trimethoprim/sulfamethoxazole and fosfomycin, was performed using the disk diffusion method on Mueller-Hinton agar. ESBL-production was screened by the double-disk synergy test and confirmed by molecular characterization using PCR (polymerase chain reaction) amplification and sequencing of ESBL encoding genes. Clonality of the avian and human strains was performed using the Multi Locus Sequencing Typing method (MLST). Forty-five isolated avian Salmonella strains and 37 human collected ones were studied. Five S. enterica serotypes were found in avian isolates (mainly Kentucky) and 9 from human ones (essentially Infantis). 51.11% and 26.6% of the avian isolates were resistant to ciprofloxacin and cefotaxime, respectively, whereas human isolates were less resistant to these antibiotics (13.5% to ciprofloxacin and 16.2% to cefotaxime). Eighteen (12 avian and 6 human) strains were found to produce ESBLs, which were identified as bla CTX-M-1 (n = 12), bla CTX-M-15 (n = 5) and bla TEM group (n = 8). Interestingly, seven of the ESBL-producing strains (5 avian and 2 human) were of the same ST (ST15) and

Irradiation studies of local Streptomyces strains for higher antibiotic producing capacity. Part of a coordinated programme on radiation microbiology

International Nuclear Information System (INIS)

Kintanar, Q.L.

1978-06-01

The 14 mutants produced by sequential exposure to gamma and ultraviolet irradiation were found to belong to different fundamental types of variants differing in morphology, stability, and metabolite spectra from the parent strain. The first hour mutants, M-1 to M-4 could be considered as belonging to the first category of mutants. Metabolites produced were the same as the parent but differ only in quantity. One was a morphological mutant, M-4 which differed from the parent strain in the production of a brown pigment and conidia, and lack of aerial mycelium. It was found to be most stable and capable of producing high antibiotic yield. The rest of the mutants, M-5 to M-14 could be grouped in the second category. The synthesis of one or more metabolites of the parent strain has been lost by mutation. Unexpectedly, a mutant, M-9 instead of synthesizing either oxytetracycline or tetracycline produced chlortetracycline. Coconut water was found inhibitory to the production of antibiotics by the parent strain and the high and low producing mutants. Modifying the medium by incorporating phosphate and adjusting the initial pH to 4.75 raised the antibiotic yield of the 10% coconut water supplemented medium of M-4 more than the control. Higher pH than the optimum shortened the lag phase but reduced the antibiotic yield while a lower initial pH prevented the growth of the organism giving negligible yield. A reduction of pH to pH 4.5 for the initial 48 hours lengthened the lag phase with almost no adverse effect on the yield. The incorporation of large amounts of coconut water aggravated the amino acid imbalance of the medium

Techno-functional differentiation of two vitamin B12 producing Lactobacillus plantarum strains: an elucidation for diverse future use.

Science.gov (United States)

Bhushan, Bharat; Tomar, S K; Chauhan, Arun

2017-01-01

An appropriate selection of Lactobacillus strain (probiotic/starter/functional) on the basis of its techno-functional characteristics is required before developing a novel fermented functional food. We compared vitamin B 12 (B 12 , cobalamin) producing Lactobacillus plantarum isolates, BHM10 and BCF20, for functional (vitamin over-production, genomic insight to B 12 structural genes, and probiotic attributes) and technological [milks (skim and soy) fermentation and B 12 bio-fortification] characteristics. Addition of B 12 precursors (5-amonolevulinate and dimethylbenzimidazole) to cobalamin-free fermentation medium increased vitamin production in BHM10, BCF20, and DSM20016 (a positive standard) by 3.4-, 4.4-, and 3.86-folds, respectively. Three important B 12 structural genes were detected in L. plantarum species (strains BHM10 and BCF20) by PCR for the first time. The gene sequences were submitted to NCBI GenBank and found phylogenetically closer to respective sequences in B 12 producing Lactobacillus reuteri strains. During comparative probiotic testing, BCF20 showed significantly higher (p < 0.05 to p < 0.001) gastrointestinal tolerance and cell surface hydrophobicity (p < 0.05) than BHM10. Moreover, only BCF20 was found positive for BSH activity and also exhibited comparatively better antagonistic potential against potent pathogens. Conversely, high acid and bile susceptible strain BHM10 displayed significantly higher soy milk fermentation and resultant B 12 bio-fortification abilities during technological testing. Two B 12 quantification techniques, UFLC and competitive immunoassay, confirmed the in vitro and in situ bio-production of bio-available form of B 12 after BHM10 fermentation. Conclusively, techno-functional differentiation of two B 12 producing strains elucidates their diverse future use; BCF20 either for B 12 over-production (in vitro) or as a probiotic candidate, while BHM10 for cobalamin bio-fortification (in situ) in soy milk.

Biological characterization of lead-enhanced exopolysaccharide produced by a lead resistant Enterobacter cloacae strain P2B.

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Naik, Milind Mohan; Pandey, Anju; Dubey, Santosh Kumar

2012-09-01

A lead resistant bacterial strain isolated from effluent of lead battery manufacturing company of Goa, India has been identified as Enterobacter cloacae strain P2B based on morphological, biochemical characters, FAME profile and 16S rDNA sequence data. This bacterial strain could resist lead nitrate up to 1.6 mM. Significant increase in exopolysaccharide (EPS) production was observed as the production increased from 28 to 108 mg/L dry weight when exposed to 1.6 mM lead nitrate in Tris buffered minimal medium. Fourier-transformed infrared spectroscopy of this EPS revealed presence of several functional groups involved in metal binding viz. carboxyl, hydroxyl and amide groups along with glucuronic acid. Gas chromatography coupled with mass spectrometry analysis of alditol-acetate derivatives of acid hydrolysed EPS produced in presence of 1.6 mM lead nitrate demonstrated presence of several neutral sugars such as rhamnose, arabinose, xylose, mannose, galactose and glucose, which contribute to lead binding hydroxyl groups. Scanning electron microscope coupled with energy dispersive X-ray spectrometric analysis of this lead resistant strain exposed to 1.6 mM lead nitrate interestingly revealed mucous EPS surrounding bacterial cells which sequestered 17 % lead (as weight %) extracellularly and protected the bacterial cells from toxic effects of lead. This lead resistant strain also showed multidrug resistance. Thus these results significantly contribute to better understanding of structure, function and environmental application of lead-enhanced EPSs produced by bacteria. This lead-enhanced biopolymer can play a very important role in bioremediation of several heavy metals including lead.

Preparation and antimicrobial action of three tryptic digested functional molecules of bovine lactoferrin.

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Nilisha Rastogi

Full Text Available Lactoferrin is an 80 kDa bilobal, iron binding glycoprotein which is primarily antimicrobial in nature. The hydrolysis of lactoferrin by various proteases in the gut produces several functional fragments of lactoferrin which have varying molecular sizes and properties. Here, bovine lactoferrin has been hydrolyzed by trypsin, the major enzyme present in the gut, to produce three functional molecules of sizes approximately 21 kDa, 38 kDa and 45 kDa. The molecules have been purified using ion exchange and gel filtration chromatography and identified using N-terminal sequencing, which reveals that while the 21 kDa molecule corresponds to the N2 domain (21LF, the 38 kDa represents the whole C-lobe (38LF and the 45 kDa is a portion of N1 domain of N-lobe attached to the C-lobe (45LF. The iron binding and release properties of 21LF, 38LF and 45LF have been studied and compared. The sequence and structure analysis of the portions of the excision sites of LF from various species have been done. The antibacterial properties of these three molecules against bacterial strains, Streptococcus pyogenes, Escherichia coli, Yersinia enterocolitica and Listeria monocytogenes were investigated. The antifungal action of the molecules was also evaluated against Candida albicans. This is the first report on the antimicrobial actions of the trypsin cleaved functional molecules of lactoferrin from any species.

[Antagonism against Beauveria bassiana by lipopeptide metabolites produced by entophyte Bacillus amyloliquefaciens strain SWB16].

Science.gov (United States)

Wang, Jingjie; Zhao, Dongyang; Liu, Yonggui; Ao, Xiang; Fan, Rui; Duan, Zhengqiao; Liu, Yanping; Chen, Qianqian; Jin, Zhixiong; Wan, Yongji

2014-07-04

We screened bacterial strains that have strong antagonism against Beauveria bassiana, an important pathogen of silkworm industry, and detected the antagonistic activity of lipopeptide metabolites. We identified bacterium SWB16 by morphological observation, physiological and biochemical experiments, 16SrRNA, and gyrA gene sequence analysis, tested antagonistic activity of strain SWB16 against Beauveria bassiana by measuring the inhibition zone diameter using filter paper diffusion method (Kirby-Bauer method), obtained lipopeptide metabolites of the strain using methanol extraction and observed the antagonism of strain SWB16 lipopeptide extracts against the conidia and hyphae of Beauveria bassiana, detected main ingredients and genes of lipopeptide metabolites by high-performance liquid chromatography-mass spectrometry and PCR amplification. SWB16 isolated from tissue of plant Dioscorea zingiberensis C. H. Wright belongs to Bacillus amyloliquefaciens and showed high antagonistic activity to Beauveria bassiana, and the lipopeptide extracts of isolate SWB16 exhibited significant inhibition to conidial germination and mycelial growth of Beauveria bassiana. The result of mass spectrometric detection indicated main component of the lipopeptide metabolites were fengcin and iturin, and genes fenB, ituA involved in the synthesis of them were amplified in the genome. Bacillus amyloliquefaciens strain SWB16 could produce lipopeptide antibiotics with strong antagonism to the entomopathogenic fungus Beauveria bassiana, and the results suggested that strain SWB16 has potential application value for controlling white muscardine of economic insects including silkworm.

Isolation of a yeast strain able to produce a polygalacturonase with maceration activity of cassava roots

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María Alicia Martos

2013-06-01

Full Text Available The objective of the present study was the isolation of a yeast strain, from citrus fruit peels, able to produce a polygalacturonase by submerged fermentation with maceration activity of raw cassava roots. Among 160 yeast strains isolated from citrus peels, one strain exhibited the strongest pectinolytic activity. This yeast was identified as Wickerhamomyces anomalus by 5.8S-ITS RFLP analysis and confirmed by amplification of the nucleotide sequence. The yeast produced a polygalacturonase (PG in Erlenmeyer shake flasks containing YNB, glucose, and citrus pectin. PG synthesis occurred during exponential growth phase, reaching 51 UE.mL-1 after 8 hours of fermentation. A growth yield (Yx/s of 0.43 gram of cell dry weight per gram of glucose consumed was obtained, and a maximal specific growth rate (µm of 0.346 h-1 was calculated. The microorganism was unable to assimilate sucrose, galacturonic acid, polygalacturonic acid, or citrus pectin, but it required glucose as carbon and energy source and polygalacturonic acid or citrus pectin as inducers of enzyme synthesis. The crude enzymatic extract of Wickerhamomyces anomalus showed macerating activity of raw cassava. This property is very important in the production of dehydrated mashed cassava, a product of regional interest in the province of Misiones, Argentina.

Draft Genome Sequence of Lactobacillus delbrueckii subsp. bulgaricus CRL871, a Folate-Producing Strain Isolated from a Northwestern Argentinian Yogurt.

Science.gov (United States)

Laiño, Jonathan Emiliano; Hebert, Elvira María; Savoy de Giori, Graciela; LeBlanc, Jean Guy

2015-06-25

Lactobacillus delbrueckii subsp. bulgaricus CRL871 is the first strain of L. delbrueckii subsp. bulgaricus reported as a folate-producing strain. We report the draft genome sequence of L. delbrueckii subsp. bulgaricus CRL871 (2,063,981 bp, G+C content of 49.1%). This strain is of great biotechnological importance to the dairy industry because it constitutes an alternative to folic acid fortification. Copyright © 2015 Laiño et al.

Biosurfactant production from marine hydrocarbon-degrading consortia and pure bacterial strains using crude oil as carbon source

OpenAIRE

Antoniou, Eleftheria; Fodelianakis, Stilianos; Korkakaki, Emmanouela; Kalogerakis, Nicolas

2015-01-01

Biosurfactants (BS) are green amphiphilic molecules produced by microorganisms during biodegradation, increasing the bioavailability of organic pollutants. In this work, the BS production yield of marine hydrocarbon degraders isolated from Elefsina bay in Eastern Mediterranean Sea has been investigated. The drop collapse test was used as a preliminary screening test to confirm biosurfactant producing strains or mixed consortia. The community structure of the best consortia based on the drop c...

Effectiveness of halo-tolerant, auxin producing Pseudomonas and Rhizobium strains to improve osmotic stress tolerance in mung bean (Vigna radiata L.

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Maqshoof Ahmad

2013-12-01

Full Text Available Halo-tolerant, auxin producing bacteria could be used to induce salt tolerance in plants. A number of Rhizobium and auxin producing rhizobacterial strains were assessed for their ability to tolerate salt stress by conducting osmoadaptation assay. The selected strains were further screened for their ability to induce osmotic stress tolerance in mung bean seedlings under salt-stressed axenic conditions in growth pouch/jar trials. Three most effective strains of Rhizobium and Pseudomonas containing ACC-deaminase were evaluated in combination, for their ability to induce osmotic stress tolerance in mung bean at original, 4, and 6 dS m-1 under axenic conditions. Results showed that sole inoculation of Rhizobium and Pseudomonas strains improved the total dry matter up to 1.4, and 1.9 fold, respectively, while the increase in salt tolerance index was improved up to 1.3 and 2.0 fold by the Rhizobium and Pseudomonas strains, respectively. However, up to 2.2 fold increase in total dry matter and salt tolerance index was observed due to combined inoculation of Rhizobium and Pseudomonas strains. So, combined application of Rhizobium and Pseudomonas strains could be explored as an effective strategy to induce osmotic stress tolerance in mung bean.

Physicochemical properties and membrane biofouling of extra-cellular polysaccharide produced by a Micrococcus luteus strain.

Science.gov (United States)

Feng, Lei; Li, Xiufen; Song, Ping; Du, Guocheng; Chen, Jian

2014-07-01

The physicochemical properties of the extra-cellular polysaccharide (EPS) produced by a Micrococcus luteus strain, a dominating strain isolated from membrane biofouling layer, were determined in this study. The EPS isolated from this strain was measured to have an average molecular weight of 63,540 Da and some typical polysaccharide absorption peaks in Fourier transform infrared spectrum. Monosaccharide components of the EPS contained rhamnose, fucose, arabinose, xylose, mannose, galactose and glucose in a molar ratio of 0.2074:0.0454:0.0262:0.0446:1.7942:1.2086:0.4578. Pseudo plastic properties were also observed for the EPS through the rheological measurement. The EPS was further characterized for its behavior to cause membrane flux decline. The results showed that both flux declines for polyvinylidenefluoride (PVDF) and polypropylene membranes became more severe as EPS feed concentration increased. A higher irreversible fouling for the PVDF membrane suggested that the EPS had the larger fouling potential to this microfiltration membrane.

Atypical patterns of neural infection produced in mice by drug-resistant strains of herpes simplex virus.

Science.gov (United States)

Field, H J; Anderson, J R; Wildy, P

1982-03-01

Mice inoculated intracerebrally (i.c.) with a mutant strain of HSV were found to develop cataracts 1 to 2 months after inoculation. Cataract formation was subsequently shown to follow an acute retinitis which commenced within 1 week of inoculation. The mutant had been selected for high resistance to the nucleoside analogue acyclovir and has been shown previously to be defective in the induction of thymidine kinase and also to express an altered DNA polymerase. The LD50 for mice inoculated i.c. was greater than 10(5) p.f.u. compared with approx 7 p.f.u. for the parental strain. Studies of virus replication following i.c. inoculation with a sublethal dose of the mutant revealed that only small amounts of infectious virus were produced in the brain, but during a period from 6 to 12 days after inoculation vigorous replication occurred in retinal tissue, producing very high titres of virus.

Structure of an extracellular polysaccharide produced by Lactobacillus rhamnosus strain C83

Energy Technology Data Exchange (ETDEWEB)

Vanhaverbeke, C.; Bosso, C.; Colin-Morel, P.; Gey, C.; Heyraud, A. [Centre de Recherches sur les Macromolecules Vegetales, CNRS and Universite Joseph Fourier, B.P.53, F-38041 Grenoble (France); Gamar-Nourani, L.; Blondeau, K.; Simonet, J.-M. [Institut de Genetique et Microbiologie, Laboratoire de Genetique Moleculaire des Bacteries d' Interet Industriel, CNRS URA 2225, Batiment 360, Universite de Paris Sud, F-91405 Orsay (France)

1998-12-31

The extracellular polysaccharide produced by Lactobacillus rhamnosus strain C83 was found to be composed of d-glucose and d-galactose in a molar ratio of 2:3. The primary structure of the polysaccharide was shown by sugar analysis, methylation analysis, FABMS, partial acid hydrolysis and nuclear magnetic resonance (NMR) spectroscopy to consist of a pentasaccharide repeating unit having the following structure:-3)-{alpha}-d-Glcp-(1-2)-{beta}-d-Galf-(1-6)-{alpha}-d-Galp-(1-6) -{alpha}-d-Glcp-(1-3)-{beta}-d-Galf-(1-. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

Structure of an extracellular polysaccharide produced by Lactobacillus rhamnosus strain C83

International Nuclear Information System (INIS)

Vanhaverbeke, C.; Bosso, C.; Colin-Morel, P.; Gey, C.; Heyraud, A.; Gamar-Nourani, L.; Blondeau, K.; Simonet, J.-M.

1998-01-01

The extracellular polysaccharide produced by Lactobacillus rhamnosus strain C83 was found to be composed of d-glucose and d-galactose in a molar ratio of 2:3. The primary structure of the polysaccharide was shown by sugar analysis, methylation analysis, FABMS, partial acid hydrolysis and nuclear magnetic resonance (NMR) spectroscopy to consist of a pentasaccharide repeating unit having the following structure:-3)-α-d-Glcp-(1-2)-β-d-Galf-(1-6)-α-d-Galp-(1-6) -α-d-Glcp-(1-3)-β-d-Galf-(1-. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

Chemical and serologic definition of two unique D region-encoded molecules in the wild-derived mouse strain B10.GAA37.

Science.gov (United States)

Lillehoj, E P; Walsh, W D; Potter, T; Lee, D R; Coligan, J E; Hansen, T H

1984-12-01

Detailed serologic and biochemical characterization of D region products of the wild-derived mouse strain B10.GAA37 (Dw16) were performed and compared with previous studies of the D region products of the H-2d,b, and q haplotypes. Serologic analysis revealed that the antigens encoded by the Dw16 region express a unique combination of specificities defined by monoclonal antibodies (mAb) with established activity for the Ld and Dd molecules. Two out of five anti-Ld-reactive mAb reacted with B10.GAA37 cells, whereas one of three anti-Dd mAb showed B10.GAA37 reactivity. Sequential immunoprecipitation of B10.GAA37 antigens demonstrated the existence of at least two antigenically distinct molecules (designated Dw16 and Lw16) encoded by genes associated with the Dw16 region. Peptide map comparisons of the Dw16 and Lw16 molecules defined multiple differences in their primary protein structure, suggesting they are products of separate genes. Structural comparisons of the Lw16 and Dw16 molecules with the Ld and Dd molecules implied a) that the Dw16 and Dd regions did not result from a recent evolutionary divergence of a common primordial haplotype, and b) that the Lw16 and Dw16 molecules are more structurally homologous to each other than the Ld and Dd molecules are. Comparison of these findings with our previous studies of antigens encoded by the D regions suggest that each of these haplotypes has unique properties in terms of the number of gene products expressed and/or the structural relatedness of products of the same region.

Strain-Level Diversity of Secondary Metabolism in Streptomyces albus

Science.gov (United States)

Seipke, Ryan F.

2015-01-01

Streptomyces spp. are robust producers of medicinally-, industrially- and agriculturally-important small molecules. Increased resistance to antibacterial agents and the lack of new antibiotics in the pipeline have led to a renaissance in natural product discovery. This endeavor has benefited from inexpensive high quality DNA sequencing technology, which has generated more than 140 genome sequences for taxonomic type strains and environmental Streptomyces spp. isolates. Many of the sequenced streptomycetes belong to the same species. For instance, Streptomyces albus has been isolated from diverse environmental niches and seven strains have been sequenced, consequently this species has been sequenced more than any other streptomycete, allowing valuable analyses of strain-level diversity in secondary metabolism. Bioinformatics analyses identified a total of 48 unique biosynthetic gene clusters harboured by Streptomyces albus strains. Eighteen of these gene clusters specify the core secondary metabolome of the species. Fourteen of the gene clusters are contained by one or more strain and are considered auxiliary, while 16 of the gene clusters encode the production of putative strain-specific secondary metabolites. Analysis of Streptomyces albus strains suggests that each strain of a Streptomyces species likely harbours at least one strain-specific biosynthetic gene cluster. Importantly, this implies that deep sequencing of a species will not exhaust gene cluster diversity and will continue to yield novelty. PMID:25635820

Isolation and characterization of biosurfactant-producing Alcanivorax strains: hydrocarbon accession strategies and alkane hydroxylase gene analysis.

Science.gov (United States)

Olivera, Nelda L; Nievas, Marina L; Lozada, Mariana; Del Prado, Guillermo; Dionisi, Hebe M; Siñeriz, Faustino

2009-01-01

Biosurfactant-producing bacteria belonging to the genera Alcanivorax, Cobetia and Halomonas were isolated from marine sediments with a history of hydrocarbon exposure (Aristizábal and Gravina Peninsulas, Argentina). Two Alcanivorax isolates were found to form naturally occurring consortia with strains closely related to Pseudomonas putida and Microbacterium esteraromaticum. Alkane hydroxylase gene analysis in these two Alcanivorax strains resulted in the identification of two novel alkB genes, showing 86% and 60% deduced amino acid sequence identity with those of Alcanivorax sp. A-11-3 and Alcanivorax dieselolei P40, respectively. In addition, a gene homologous to alkB2 from Alcanivorax borkumensis was present in one of the strains. The consortium formed by this strain, Alcanivorax sp. PA2 (98.9% 16S rRNA gene sequence identity with A. borkumensis SK2(T)) and P. putida PA1 was characterized in detail. These strains form cell aggregates when growing as mixed culture, though only PA2 was responsible for biosurfactant activity. During exponential growth phase of PA2, cells showed high hydrophobicity and adherence to hydrocarbon droplets. Biosurfactant production was only detectable at late growth and stationary phases, suggesting that it is not involved in initiating oil degradation and that direct interfacial adhesion is the main hydrocarbon accession mode of PA2. This strain could be useful for biotechnological applications due to its biosurfactant production, catabolic and aggregation properties.

Comparative genomic analysis of single-molecule sequencing and hybrid approaches for finishing the Clostridium autoethanogenum JA1-1 strain DSM 10061 genome

Energy Technology Data Exchange (ETDEWEB)

Brown, Steven D [ORNL; Nagaraju, Shilpa [LanzaTech; Utturkar, Sagar M [ORNL; De Tissera, Sashini [LanzaTech; Segovia, Simón [LanzaTech; Mitchell, Wayne [LanzaTech; Land, Miriam L [ORNL; Dassanayake, Asela [LanzaTech; Köpke, Michael [LanzaTech

2014-01-01

Background Clostridium autoethanogenum strain JA1-1 (DSM 10061) is an acetogen capable of fermenting CO, CO2 and H2 (e.g. from syngas or waste gases) into biofuel ethanol and commodity chemicals such as 2,3-butanediol. A draft genome sequence consisting of 100 contigs has been published. Results A closed, high-quality genome sequence for C. autoethanogenum DSM10061 was generated using only the latest single-molecule DNA sequencing technology and without the need for manual finishing. It is assigned to the most complex genome classification based upon genome features such as repeats, prophage, nine copies of the rRNA gene operons. It has a low G + C content of 31.1%. Illumina, 454, Illumina/454 hybrid assemblies were generated and then compared to the draft and PacBio assemblies using summary statistics, CGAL, QUAST and REAPR bioinformatics tools and comparative genomic approaches. Assemblies based upon shorter read DNA technologies were confounded by the large number repeats and their size, which in the case of the rRNA gene operons were ~5 kb. CRISPR (Clustered Regularly Interspaced Short Paloindromic Repeats) systems among biotechnologically relevant Clostridia were classified and related to plasmid content and prophages. Potential associations between plasmid content and CRISPR systems may have implications for historical industrial scale Acetone-Butanol-Ethanol (ABE) fermentation failures and future large scale bacterial fermentations. While C. autoethanogenum contains an active CRISPR system, no such system is present in the closely related Clostridium ljungdahlii DSM 13528. A common prophage inserted into the Arg-tRNA shared between the strains suggests a common ancestor. However, C. ljungdahlii contains several additional putative prophages and it has more than double the amount of prophage DNA compared to C. autoethanogenum. Other differences include important metabolic genes for central metabolism (as an additional hydrogenase and the absence of a

Intra-operative ultrasound hand-held strain imaging for the visualization of ablations produced in the liver with a toroidal HIFU transducer: first in vivo results

Energy Technology Data Exchange (ETDEWEB)

Chenot, J; Melodelima, D; N' Djin, W A; Souchon, Remi; Rivoire, M; Chapelon, J Y, E-mail: jeremy.chenot@inserm.f [Inserm, U556, Lyon, F-69003 (France)

2010-06-07

The use of hand-held ultrasound strain imaging for the intra-operative real-time visualization of HIFU (high-intensity focused ultrasound) ablations produced in the liver by a toroidal transducer was investigated. A linear 12 MHz ultrasound imaging probe was used to obtain radiofrequency signals. Using a fast cross-correlation algorithm, strain images were calculated and displayed at 60 frames s{sup -1}, allowing the use of hand-held strain imaging intra-operatively. Fourteen HIFU lesions were produced in four pigs. Intra-operative strain imaging of HIFU ablations in the liver was feasible owing to the high frame rate. The correlation between dimensions measured on gross pathology and dimensions measured on B-mode images and on strain images were R = 0.72 and R = 0.94 respectively. The contrast between ablated and non-ablated tissue was significantly higher (p < 0.05) in the strain images (22 dB) than in the B-mode images (9 dB). Strain images allowed equivalent or improved definition of ablated regions when compared with B-mode images. Real-time intra-operative hand-held strain imaging seems to be a promising complement to conventional B-mode imaging for the guidance of HIFU ablations produced in the liver during an open procedure. These results support that hand-held strain imaging outperforms conventional B-mode ultrasound and could potentially be used for the assessment of thermal therapies.

Pathway Construction in Corynebacterium glutamicum and Strain Engineering To Produce Rare Sugars from Glycerol.

Science.gov (United States)

Yang, Jiangang; Zhu, Yueming; Men, Yan; Sun, Shangshang; Zeng, Yan; Zhang, Ying; Sun, Yuanxia; Ma, Yanhe

2016-12-21

Rare sugars are valuable natural products widely used in pharmaceutical and food industries. In this study, we expected to synthesize rare ketoses from abundant glycerol using dihydroxyacetone phosphate (DHAP)-dependent aldolases. First, a new glycerol assimilation pathway was constructed to synthesize DHAP. The enzymes which convert glycerol to 3-hydroxypropionaldehyde and l-glyceraldehyde were selected, and their corresponding aldehyde synthesis pathways were constructed in vivo. Four aldol pathways based on different aldolases and phosphorylase were gathered. Next, three pathways were assembled and the resulting strains synthesized 5-deoxypsicose, 5-deoxysorbose, and 5-deoxyfructose from glucose and glycerol and produce l-fructose, l-tagatose, l-sorbose, and l-psicose with glycerol as the only carbon source. To achieve higher product titer and yield, the recombinant strains were further engineered and fermentation conditions were optimized. Fed-batch culture of engineered strains obtained 38.1 g/L 5-deoxypsicose with a yield of 0.91 ± 0.04 mol product per mol of glycerol and synthesized 20.8 g/L l-fructose, 10.3 g/L l-tagatose, 1.2 g/L l-sorbose, and 0.95 g/L l-psicose.

Enzymes produced by halotolerant spore-forming gram-positive bacterial strains isolated from a resting habitat (Restinga de Jurubatiba) in Rio de Janeiro, Brazil: focus on proteases.

Science.gov (United States)

D Santos, Anderson Fragoso; Pacheco, Clarissa Almeida; Valle, Roberta D Santos; Seldin, Lucy; D Santos, André Luis Souza

2014-12-01

The screening for hydrolases-producing, halotolerant, and spore-forming gram-positive bacteria from the root, rhizosphere, and non-rhizosphere soil of Blutaparon portulacoides, a plant found in the Restinga de Jurubatiba located at the northern region of Rio de Janeiro State, Brazil, resulted in the isolation of 22 strains. These strains were identified as Halobacillus blutaparonensis (n = 2), Oceanobacillus picturae (n = 5), and Oceanobacillus iheyensis (n = 15), and all showed the ability to produce different extracellular enzymes. A total of 20 isolates (90.9 %) showed activity for protease, 5 (22.7 %) for phytase, 3 (13.6 %) for cellulase, and 2 (9.1 %) for amylase. Some bacterial strains were capable of producing three (13.6 %) or two (9.1 %) distinct hydrolytic enzymes. However, no bacterial strain with ability to produce esterase and DNase was observed. The isolate designated M9, belonging to the species H. blutaparonensis, was the best producer of protease and also yielded amylase and phytase. This strain was chosen for further studies regarding its protease activity. The M9 strain produced similar amounts of protease when grown either without or with different NaCl concentrations (from 0.5 to 10 %). A simple inspection of the cell-free culture supernatant by gelatin-sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed the presence of three major alkaline proteases of 40, 50, and 70 kDa, which were fully inhibited by phenylmethylsulfonyl fluoride (PMSF) and tosyl-L-phenylalanine chloromethyl ketone (TPCK) (two classical serine protease inhibitors). The secreted proteases were detected in a wide range of temperature (from 4 to 45 °C) and their hydrolytic activities were stimulated by NaCl (up to 10 %). The serine proteases produced by the M9 strain cleaved gelatin, casein, albumin, and hemoglobin, however, in different extensions. Collectively, these results suggest the potential use of the M9 strain in biotechnological

Isolation and screening of strains producing high amounts of rutin degrading enzymes from Fagopyrum tataricum seeds.

Science.gov (United States)

Zheng, Ya-Di; Luo, Qing-Lin; Zhou, Mei-Liang; Wang, De-Zhou; Zhang, Ye-Dong; Shao, Ji-Rong; Zhu, Xue-Mei; Tang, Yu

2013-02-01

The rutin degrading enzyme (RDE) was isolated and purified from tartary buckwheat seeds. The RDE was purified about 11.34-fold and its final yield was 3.5%, which was very low, due to our purification strategy of giving priority to purity over yield. The RDE molecular weight was estimated to be about 60 kDa. When rutin was used as substrate, an optimal enzyme activity was seen at around pH 5.0 and 40 °C. Strains isolation strategy characterized by the use of rutin as sole carbon source in enrichment cultures was used to isolate RDE-producing strains. Then the active strains were identified by morphology characterization and 18s rDNA-ITS (Internal Transcribed Spacer) gene sequencing. Three isolates coded as B3, W2, Y2 were successfully isolated from fusty Fagopyrum tataricum flour cultures. Strain B3 possessed the highest unit activity among these three strains, and its total activity reached up to 171.0 Unit. The active isolate (B3) could be assigned to Penicillium farinosum. When the Penicillium farinosum strains were added to tartary buckwheat flour cultures at pH 5.0, 30 °C after 5 days fermentation, the quercetin production raised up to 1.78 mg/l, almost 5.1 times higher than the fermentation without the above active strains. Hence, a new approach was available to utilize microorganism-aided fermentation for effective quercetin extraction from Fagopyrum tataricum seeds. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Isolation and characterization of biosurfactant producing bacteria from Persian Gulf (Bushehr provenance)

International Nuclear Information System (INIS)

Hassanshahian, Mehdi

2014-01-01

Highlights: • Biosurfactant producing bacteria were isolated from Persian Gulf. • There is high diversity of biosurfactant producing bacteria in the Persian Gulf. • These bacteria are very useful for management of oil pollution in the sea. - Abstract: Biosurfactants are surface active materials that are produced by some microorganisms. These molecules increase biodegradation of insoluble pollutants. In this study sediments and seawater samples were collected from the coastline of Bushehr provenance in the Persian Gulf and their biosurfactant producing bacteria were isolated. Biosurfactant producing bacteria were isolated by using an enrichment method in Bushnell-Hass medium with diesel oil as the sole carbon source. Five screening tests were used for selection of Biosurfactant producing bacteria: hemolysis in blood agar, oil spreading, drop collapse, emulsification activity and Bacterial Adhesion to Hydrocarbon test (BATH). These bacteria were identified using biochemical and molecular methods. Eighty different colonies were isolated from the collected samples. The most biosurfactant producing isolates related to petrochemical plants of Khark Island. Fourteen biosurfactant producing bacteria were selected between these isolates and 7 isolates were screened as these were predominant producers that belong to Shewanella alga, Shewanella upenei, Vibrio furnissii, Gallaecimonas pentaromativorans, Brevibacterium epidermidis, Psychrobacter namhaensis and Pseudomonas fluorescens. The largest clear zone diameters in oil spreading were observed for G. pentaromativorans strain O15. Also, this strain has the best emulsification activity and reduction of surface tension, suggesting it is the best of thee isolated strains. The results of this study confirmed that there is high diversity of biosurfactant producing bacteria in marine ecosystem of Iran and by application of these bacteria in petrochemical waste water environmental problems can be assisted

NATO Advanced Research Workshop on Methods and Mechanisms for Producing Ions from Large Molecules

CERN Document Server

Ens, Werner

1991-01-01

A NATO Advanced Research Workshop on Methods and Mechanisms for Producing Ions from Large Molecules was held at Minaki Lodge, Minaki, Ontario, Canada, from 24 to 28 June 1990. The workshop was hosted by the time-of-flight group of the Department of Physics at the University of Manitoba, and was attended by 64 invited participants from around the world. Twenty-nine invited talks were given and 19 papers were presented as posters. Of the 48 contributions, 38 are included in these proceedings. The conference was organized to study the rapidly changing field of mass spectrometry of biomolecules. Particle-induced desorption (especially with MeV particles) has been the most effective method of producing molecular ions from biomolecules. An important part of the workshop was devoted to recent developments in this field, particularly to progress in understanding the fundamentals of the desorption process. In this respect, the meeting was similar to previous conferences in Marburg, FRG (1978); Paris, F (1980); Uppsala...

Draft Genome Sequence of Komagataeibacter rhaeticus Strain AF1, a High Producer of Cellulose, Isolated from Kombucha Tea.

Science.gov (United States)

Dos Santos, Renato Augusto Corrêa; Berretta, Andresa A; Barud, Hernane da Silva; Ribeiro, Sidney José Lima; González-García, Laura Natalia; Zucchi, Tiago Domingues; Goldman, Gustavo H; Riaño-Pachón, Diego M

2014-07-24

Here, we present the draft genome sequence of Komagatabaeicter rhaeticus strain AF1, which was isolated from Kombucha tea and is capable of producing high levels of cellulose. Copyright © 2014 dos Santos et al.

Helicusin E, Isochromophilone X and Isochromophilone XI: New Chloroazaphilones Produced by the Fungus Bartalinia robillardoides Strain LF550

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Johannes F. Imhoff

2013-03-01

Full Text Available Microbial studies of the Mediterranean sponge Tethya aurantium led to the isolation of the fungus Bartalinia robillardoides strain LF550. The strain produced a number of secondary metabolites belonging to the chloroazaphilones. This is the first report on the isolation of chloroazaphilones of a fungal strain belonging to the genus Bartalinia. Besides some known compounds (helicusin A (1 and deacetylsclerotiorin (2, three new chloroazaphilones (helicusin E (3; isochromophilone X (4 and isochromophilone XI (5 and one new pentaketide (bartanolide (6 were isolated. The structure elucidations were based on spectroscopic analyses. All isolated compounds revealed different biological activity spectra against a test panel of four bacteria: three fungi; two tumor cell lines and two enzymes.

Helicusin E, isochromophilone X and isochromophilone XI: new chloroazaphilones produced by the fungus Bartalinia robillardoides strain LF550.

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Jansen, Nils; Ohlendorf, Birgit; Erhard, Arlette; Bruhn, Torsten; Bringmann, Gerhard; Imhoff, Johannes F

2013-03-12

Microbial studies of the Mediterranean sponge Tethya aurantium led to the isolation of the fungus Bartalinia robillardoides strain LF550. The strain produced a number of secondary metabolites belonging to the chloroazaphilones. This is the first report on the isolation of chloroazaphilones of a fungal strain belonging to the genus Bartalinia. Besides some known compounds (helicusin A (1) and deacetylsclerotiorin (2)), three new chloroazaphilones (helicusin E (3); isochromophilone X (4) and isochromophilone XI (5)) and one new pentaketide (bartanolide (6)) were isolated. The structure elucidations were based on spectroscopic analyses. All isolated compounds revealed different biological activity spectra against a test panel of four bacteria: three fungi; two tumor cell lines and two enzymes.

Growth of Chlamydomonas reinhardtii in acetate-free medium when co-cultured with alginate-encapsulated, acetate-producing strains of Synechococcus sp. PCC 7002.

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Therien, Jesse B; Zadvornyy, Oleg A; Posewitz, Matthew C; Bryant, Donald A; Peters, John W

2014-01-01

The model alga Chlamydomonas reinhardtii requires acetate as a co-substrate for optimal production of lipids, and the addition of acetate to culture media has practical and economic implications for algal biofuel production. Here we demonstrate the growth of C. reinhardtii on acetate provided by mutant strains of the cyanobacterium Synechococcus sp. PCC 7002. Optimal growth conditions for co-cultivation of C. reinhardtii with wild-type and mutant strains of Synechococcus sp. 7002 were established. In co-culture, acetate produced by a glycogen synthase knockout mutant of Synechococcus sp. PCC 7002 was able to support the growth of a lipid-accumulating mutant strain of C. reinhardtii defective in starch production. Encapsulation of Synechococcus sp. PCC 7002 using an alginate matrix was successfully employed in co-cultures to limit growth and maintain the stability. The ability of immobilized strains of the cyanobacterium Synechococcus sp. PCC 7002 to produce acetate at a level adequate to support the growth of lipid-accumulating strains of C. reinhartdii offers a potentially practical, photosynthetic alternative to providing exogenous acetate into growth media.

Characterization of extracellular vitamin B12 producing Lactobacillus plantarum strains and assessment of the probiotic potentials.

Science.gov (United States)

Li, Ping; Gu, Qing; Yang, Lanlan; Yu, Yue; Wang, Yuejiao

2017-11-01

We investigated extracellular vitamin B 12 -producing Lactobacillus strains and their characteristics in tolerance to environmental stresses, gastric acid and bile salts. Two isolates, Lactobacillus plantarum LZ95 and CY2, showed high extracellular B 12 production, 98±15μg/L and 60±9μg/L respectively. Extracellular B 12 from LZ95 were identified as adenosylcobalamin and methylcobalamin using a combination of solid phase extraction and reverse-phase HPLC, while that from CY2 was adenosylcobalamin. Both strains grew under environmental stresses, and LZ95 exhibited better tolerance to low temperature and high ethanol concentration. LZ95 also showed good viability when exposed to gastric acid (pH 2.0 and 3.0) and bile salts (0.3%) as well as good adhesion to Caco-2 cells. The viability of CY2 was significantly reduced under low pH and exposure to bile salt. Together, extracellular B 12 producer LZ95 with good probiotic properties might be a candidate for in situ B 12 fortification in the food industry. Copyright © 2017 Elsevier Ltd. All rights reserved.

Silver nanoparticle production by Rhizopus stolonifer and its antibacterial activity against extended spectrum β-lactamase producing (ESBL) strains of Enterobacteriaceae

International Nuclear Information System (INIS)

Banu, Afreen; Rathod, Vandana; Ranganath, E.

2011-01-01

Highlights: → Silver nanoparticle production by using Rhizopus stolonifer. → Antibacterial activity of silver nanoparticles against extended spectrum β-lactamase producing (ESBL) strains of Enterobacteriaceae. → Synergistic effect of antibiotics with silver nanoparticles towards ESBL-strains. → Characterization of silver nanoparticles made by UV-vis spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transformed infrared (FTIR) spectroscopy, atomic force microscopy (AFM). -- Abstract: This report focuses on the synthesis of silver nanoparticles using the fungus, Rhizopus stolonifer and its antimicrobial activity. Research in nanotechnology highlights the possibility of green chemistry pathways to produce technologically important nanomaterials. Characterization of newly synthesized silver nanoparticles was made by UV-visible absorption spectroscopy, scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier transform infrared (FTIR) spectroscopy and atomic force microscope (AFM). TEM micrograph revealed the formation of spherical nanoparticles with size ranging between 3 and 20 nm. The biosynthesized silver nanoparticles (AgNPs) showed excellent antibacterial activity against ESBL-strains which includes E. coli, Proteus. sp. and Klebsiella sp.

Silver nanoparticle production by Rhizopus stolonifer and its antibacterial activity against extended spectrum {beta}-lactamase producing (ESBL) strains of Enterobacteriaceae

Energy Technology Data Exchange (ETDEWEB)

Banu, Afreen [Department of Microbiology, Gulbarga University, Gulbarga 585106, Karnataka (India); Rathod, Vandana, E-mail: drvandanarathod@rediffmail.com [Department of Microbiology, Gulbarga University, Gulbarga 585106, Karnataka (India); Ranganath, E. [Department of Microbiology, Gulbarga University, Gulbarga 585106, Karnataka (India)

2011-09-15

Highlights: {yields} Silver nanoparticle production by using Rhizopus stolonifer. {yields} Antibacterial activity of silver nanoparticles against extended spectrum {beta}-lactamase producing (ESBL) strains of Enterobacteriaceae. {yields} Synergistic effect of antibiotics with silver nanoparticles towards ESBL-strains. {yields} Characterization of silver nanoparticles made by UV-vis spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transformed infrared (FTIR) spectroscopy, atomic force microscopy (AFM). -- Abstract: This report focuses on the synthesis of silver nanoparticles using the fungus, Rhizopus stolonifer and its antimicrobial activity. Research in nanotechnology highlights the possibility of green chemistry pathways to produce technologically important nanomaterials. Characterization of newly synthesized silver nanoparticles was made by UV-visible absorption spectroscopy, scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier transform infrared (FTIR) spectroscopy and atomic force microscope (AFM). TEM micrograph revealed the formation of spherical nanoparticles with size ranging between 3 and 20 nm. The biosynthesized silver nanoparticles (AgNPs) showed excellent antibacterial activity against ESBL-strains which includes E. coli, Proteus. sp. and Klebsiella sp.

Identification and statistical optimization of fermentation conditions for a newly isolated extracellular cholesterol oxidase-producing Streptomyces cavourensis strain NEAE-42

OpenAIRE

El-Naggar, Noura El-Ahmady; El-Shweihy, Nancy M.; El-Ewasy, Sara M.

2016-01-01

Background Due to broad range of clinical and industrial applications of cholesterol oxidase, isolation and screening of bacterial strains producing extracellular form of cholesterol oxidase is of great importance. Results One hundred and thirty actinomycete isolates were screened for their cholesterol oxidase activity. Among them, a potential culture, strain NEAE-42 is displayed the highest extracellular cholesterol oxidase activity. It was selected and identified as Streptomyces cavourensis...

Candidacidal Activity of a Novel Killer Toxin from Wickerhamomyces anomalus against Fluconazole-Susceptible and -Resistant Strains

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Laura Giovati

2018-02-01

Full Text Available The isolation and characterization from the sand fly Phlebotomus perniciosus of a Wickerhamomyces anomalus yeast strain (Wa1F1 displaying the killer phenotype was recently reported. In the present work, the killer toxin (KT produced by Wa1F1 was purified and characterized, and its antimicrobial activity in vitro was investigated against fluconazole- susceptible and -resistant clinical isolates and laboratory strains of Candida albicans and C. glabrata displaying known mutations. Wa1F1-KT showed a differential killing ability against different mutant strains of the same species. The results may be useful for the design of therapeutic molecules based on Wa1F1-KT and the study of yeast resistance mechanisms.

Detecting high-density ultracold molecules using atom–molecule collision

International Nuclear Information System (INIS)

Chen, Jun-Ren; Kao, Cheng-Yang; Chen, Hung-Bin; Liu, Yi-Wei

2013-01-01

Utilizing single-photon photoassociation, we have achieved ultracold rubidium molecules with a high number density that provides a new efficient approach toward molecular quantum degeneracy. A new detection mechanism for ultracold molecules utilizing inelastic atom–molecule collision is demonstrated. The resonant coupling effect on the formation of the X 1 Σ + g ground state 85 Rb 2 allows for a sufficient number of more deeply bound ultracold molecules, which induced an additional trap loss and heating of the co-existing atoms owing to the inelastic atom–molecule collision. Therefore, after the photoassociation process, the ultracold molecules can be investigated using the absorption image of the ultracold rubidium atoms mixed with the molecules in a crossed optical dipole trap. The existence of the ultracold molecules was then verified, and the amount of accumulated molecules was measured. This method detects the final produced ultracold molecules, and hence is distinct from the conventional trap loss experiment, which is used to study the association resonance. It is composed of measurements of the time evolution of an atomic cloud and a decay model, by which the number density of the ultracold 85 Rb 2 molecules in the optical trap was estimated to be >5.2 × 10 11 cm −3 . (paper)

Benefits of combinative application of probiotic, enterocin M-producing strain Enterococcus faecium AL41 and Eleutherococcus senticosus in rabbits.

Science.gov (United States)

Lauková, Andrea; Simonová, Monika Pogány; Chrastinová, Ľubica; Plachá, Iveta; Čobanová, Klaudia; Formelová, Zuzana; Chrenková, Mária; Ondruška, Ľubomír; Strompfová, Viola

2016-03-01

This study presents the effects of the probiotic and enterocin M-producing strain Enterococcus faecium AL41 on microbiota, phagocytic activity (PA), oxidative stress, performance and biochemical parameters when applied individually or in combination with Eleutherococcus senticosus in rabbits. The novelty of the study lies in the use of our non-rabbit-derived strain (AL41 = CCM8558) which produces new enterocin M. Ninety-six post-weaned rabbits (Hyplus breed) aged 5 weeks were divided into three experimental groups, 24 in each: E. senticosus (ES, 30 g/100 kg) in feed, E. faecium AL41 (10(9) CFU/mL marked by rifampicin to differentiate it from other enterococci) in water, and ES + AL. AL41 colonized sufficiently in rabbits to reduce coliforms, staphylococci, pseudomonads and clostridia. Slight decrease in bacteria was also found in the caecum and appendix. Phagocytic activity was significantly increased in the experimental groups compared to the control group (CG) (p < 0.001; p < 0.05). Applications did not evoke oxidative stress. Biochemical parameters in blood and caecal organic acids were slightly influenced. Average daily weight gain was slightly higher in ES and AL + ES. Combinative application of E. faecium with E. senticosus can be beneficial in rabbits. AL41 strain alone and in combination with ES produced reduction in spoilage bacteria; the highest stimulation of PA was in the AL41 + ES group.

Characterization of a bacteriocin-like substance produced from a novel isolated strain of Bacillus subtilis SLYY-3

Science.gov (United States)

Li, Junfeng; Li, Hongfang; Zhang, Yuanyuan; Duan, Xiaohui; Liu, Jie

2014-12-01

In the present research, the strain SLYY-3 was isolated from sediments of Jiaozhou Bay, Qingdao, China. The strain SLYY-3, which produced a bacteriocin-like substance (BLS), was characterized to be a strain of Bacillus subtillis by biochemical profiling and 16S rDNA sequence analysis. It is the first time to report that Bacillus subtilis from Jiaozhou Bay sediments could produce a BLS. The BLS of B. subtillis SLYY-3 exhibited strong inhibitory activity against gram-positive bacteria (including Staphylococcus aureus and B. subtillis) and some fungi (including Penicillium glaucum, Aspergillus niger and Aspergillus flavus). The antimicrobial activity was detected from culture in the exponential growth phase and reached its maximum when culture entered into stationary growth phase. It was thermo-tolerant even when being kept at 100°C for 60 min without losing any activity and stable over a wide pH range from 1.0 to 12.0 while being inactivated by proteolytic enzyme and trypsin, indicating the proteinaceous nature of the BLS. The BLS was purified by precipitation with hydrochloric acid (HCl) and gel filteration (Sephadex G-100). SDS-PAGE analysis of the extracellular peptides of SLYY-3 revealed a bacteriocin-like protein with a molecular mass of 66 kDa. Altogether, these characteristics indicate the potential of the BLS for food industry as a protection against pathogenic and spoilage microorganisms.

Hydrogen production from microbial strains

Science.gov (United States)

Harwood, Caroline S; Rey, Federico E

2012-09-18

The present invention is directed to a method of screening microbe strains capable of generating hydrogen. This method involves inoculating one or more microbes in a sample containing cell culture medium to form an inoculated culture medium. The inoculated culture medium is then incubated under hydrogen producing conditions. Once incubating causes the inoculated culture medium to produce hydrogen, microbes in the culture medium are identified as candidate microbe strains capable of generating hydrogen. Methods of producing hydrogen using one or more of the microbial strains identified as well as the hydrogen producing strains themselves are also disclosed.

Pathogenicity of fumonisin-producing and nonproducing strains of Aspergillus species in section Nigri to maize ears and seedlings

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Species of Aspergillus section Nigri are commonly associated with maize kernels, and some strains can produce fumonisin mycotoxins. However, there is little information about the extent to which these fungi contribute to fumonisin contamination in grain, the damage they cause to maize ears, or their...

The origin of small and large molecule behavior in the vibrational relaxation of highly excited molecules

International Nuclear Information System (INIS)

Gordon, R.J.

1990-01-01

An explanation is proposed for the qualitatively different types of behavior that have been reported for the vibrational relaxation of highly excited diatomic and polyatomic molecules. It is argued that all of the diatomic molecules that have been studied in bulk relax adiabatically at room temperature. In contrast, large polyatomic molecules have low frequency modes which act at ''doorway'' modes for the rest of the molecules, producing an impulsive relaxation mechanism. The theoretical work of Nesbitt and Hynes showed that impulsive collisions result in an exponential decay of the average vibrational energy of a Morse oscillator, whereas adiabatic collisions produce nonexponential power law behavior. We propose that this result explains a large body of data for the vibrational relaxation of small and large molecules

The hydrocarbon-degrading marine bacterium Cobetia sp. strain MM1IDA2H-1 produces a biosurfactant that interferes with quorum sensing of fish pathogens by signal hijacking

Science.gov (United States)

Ibacache-Quiroga, C; Ojeda, J; Espinoza-Vergara, G; Olivero, P; Cuellar, M; Dinamarca, M A

2013-01-01

Summary Biosurfactants are produced by hydrocarbon-degrading marine bacteria in response to the presence of water-insoluble hydrocarbons. This is believed to facilitate the uptake of hydrocarbons by bacteria. However, these diffusible amphiphilic surface-active molecules are involved in several other biological functions such as microbial competition and intra-or inter-species communication. We report the isolation and characterization of a marine bacterial strain identified as Cobetia sp. MM1IDA2H-1, which can grow using the sulfur-containing heterocyclic aromatic hydrocarbon dibenzothiophene (DBT). As with DBT, when the isolated strain is grown in the presence of a microbial competitor, it produces a biosurfactant. Because the obtained biosurfactant was formed by hydroxy fatty acids and extracellular lipidic structures were observed during bacterial growth, we investigated whether the biosurfactant at its critical micelle concentration can interfere with bacterial communication systems such as quorum sensing. We focused on Aeromonas salmonicida subsp. salmonicida, a fish pathogen whose virulence relies on quorum sensing signals. Using biosensors for quorum sensing based on Chromobacterium violaceum and Vibrio anguillarum, we showed that when the purified biosurfactant was mixed with N-acyl homoserine lactones produced by A. salmonicida, quorum sensing was inhibited, although bacterial growth was not affected. In addition, the transcriptional activities of A. salmonicida virulence genes that are controlled by quorum sensing were repressed by both the purified biosurfactant and the growth in the presence of Cobetia sp. MM1IDA2H-1. We propose that the biosurfactant, or the lipid structures interact with the N-acyl homoserine lactones, inhibiting their function. This could be used as a strategy to interfere with the quorum sensing systems of bacterial fish pathogens, which represents an attractive alternative to classical antimicrobial therapies in fish

Biodegradation of diesel oil by a novel microbial consortium: comparison between co-inoculation with biosurfactant-producing strain and exogenously added biosurfactants.

Science.gov (United States)

Mnif, Inès; Mnif, Sami; Sahnoun, Rihab; Maktouf, Sameh; Ayedi, Younes; Ellouze-Chaabouni, Semia; Ghribi, Dhouha

2015-10-01

Bioremediation, involving the use of microorganisms to detoxify or remove pollutants, is the most interesting strategy for hydrocarbon remediation. In this aim, four hydrocarbon-degrading bacteria were isolated from oil-contaminated soil in Tunisia. They were identified by the 16S rDNA sequence analysis, as Lysinibacillus bronitolerans RI18 (KF964487), Bacillus thuringiensis RI16 (KM111604), Bacillus weihenstephanensis RI12 (KM094930), and Acinetobacter radioresistens RI7 (KJ829530). Moreover, a lipopeptide biosurfactant produced by Bacillus subtilis SPB1, confirmed to increase diesel solubility, was tested to increase diesel biodegradation along with co-inoculation with two biosurfactant-producing strains. Culture studies revealed the enhancement of diesel biodegradation by the selected consortium with the addition of SPB1 lipopeptide and in the cases of co-inoculation by biosurfactant-producing strain. In fact, an improvement of about 38.42 and 49.65 % of diesel degradation was registered in the presence of 0.1 % lipopeptide biosurfactant and when culturing B. subtilis SPB1 strain with the isolated consortium, respectively. Furthermore, the best improvement, evaluated to about 55.4 %, was recorded when using the consortium cultured with B. subtilis SPB1 and A. radioresistens RI7 strains. Gas chromatography analyses were correlated with the gravimetric evaluation of the residual hydrocarbons. Results suggested the potential applicability of the selected consortium along with the ex situ- and in situ-added biosurfactant for the effective bioremediation of diesel-contaminated water and soil.

Staphylococcus aureus produces membrane-derived vesicles that induce host cell death.

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Mamata Gurung

Full Text Available Gram-negative bacteria produce outer membrane vesicles that play a role in the delivery of virulence factors to host cells. However, little is known about the membrane-derived vesicles (MVs produced by gram-positive bacteria. The present study examined the production of MVs from Staphylococcus aureus and investigated the delivery of MVs to host cells and subsequent cytotoxicity. Four S. aureus strains tested, two type strains and two clinical isolates, produced spherical nanovesicles during in vitro culture. MVs were also produced during in vivo infection of a clinical S. aureus isolate in a mouse pneumonia model. Proteomic analysis showed that 143 different proteins were identified in the S. aureus-derived MVs. S. aureus MVs were interacted with the plasma membrane of host cells via a cholesterol-rich membrane microdomain and then delivered their component protein A to host cells within 30 min. Intact S. aureus MVs induced apoptosis of HEp-2 cells in a dose-dependent manner, whereas lysed MVs neither delivered their component into the cytosol of host cells nor induced cytotoxicity. In conclusion, this study is the first report that S. aureus MVs are an important vehicle for delivery of bacterial effector molecules to host cells.

Draft genome sequence of Paenibacillus algorifonticola sp. nov., an antimicrobial-producing strain

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Liying Zhu

2015-09-01

Full Text Available Paenibacillus algorifonticola sp. nov. is isolated from a cold spring sample from Xinjiang Uyghur Autonomous Region (China, a novel strain that can produce antimicrobial substance against human pathogenic bacteria and fungi, including Staphylococcus aureus and Candida albicans. Here we report a 7.60-Mb assembly of its genome sequence and other useful information, including the coding sequences (CDSs responsible for the biosynthesis of antibacterial factors, anaerobic respiration and several immune-associated reactions. Also, prospective studies on P. algorifonticola sp. nov. in the cold spring might offer a potential source for the discovery of bioactive compounds with medical value. The data repository is deposited on the website http://www.ncbi.nlm.nih.gov/nuccore/LAQO00000000 and the accession number is LAQO00000000.

Characterization of hydrocarbon-degrading and biosurfactant-producing Pseudomonas sp. P-1 strain as a potential tool for bioremediation of petroleum-contaminated soil.

Science.gov (United States)

Pacwa-Płociniczak, Magdalena; Płaza, Grażyna Anna; Poliwoda, Anna; Piotrowska-Seget, Zofia

2014-01-01

The Pseudomonas sp. P-1 strain, isolated from heavily petroleum hydrocarbon-contaminated soil, was investigated for its capability to degrade hydrocarbons and produce a biosurfactant. The strain degraded crude oil, fractions A5 and P3 of crude oil, and hexadecane (27, 39, 27 and 13% of hydrocarbons added to culture medium were degraded, respectively) but had no ability to degrade phenanthrene. Additionally, the presence of gene-encoding enzymes responsible for the degradation of alkanes and naphthalene in the genome of the P-1 strain was reported. Positive results of blood agar and methylene blue agar tests, as well as the presence of gene rhl, involved in the biosynthesis of rhamnolipid, confirmed the ability of P-1 for synthesis of glycolipid biosurfactant. 1H and 13C nuclear magnetic resonance, Fourier transform infrared spectrum and mass spectrum analyses indicated that the extracted biosurfactant was affiliated with rhamnolipid. The results of this study indicate that the P-1 and/or biosurfactant produced by this strain have the potential to be used in bioremediation of hydrocarbon-contaminated soils.

A Small Molecule-Screening Pipeline to Evaluate the Therapeutic Potential of 2-Aminoimidazole Molecules Against Clostridium difficile

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Rajani Thanissery

2018-06-01

Full Text Available Antibiotics are considered to be the first line of treatment for mild to moderately severe Clostridium difficile infection (CDI in humans. However, antibiotics are also risk factors for CDI as they decrease colonization resistance against C. difficile by altering the gut microbiota and metabolome. Finding compounds that selectively inhibit different stages of the C. difficile life cycle, while sparing the indigenous gut microbiota is important for the development of alternatives to standard antibiotic treatment. 2-aminoimidazole (2-AI molecules are known to disrupt bacterial protection mechanisms in antibiotic resistant bacteria such as Pseudomonas aeruginosa, Acinetobacter baumannii, and Staphylococcus aureus, but are yet to be evaluated against C. difficile. A comprehensive small molecule-screening pipeline was developed to investigate how novel small molecules affect different stages of the C. difficile life cycle (growth, toxin, and sporulation in vitro, and a library of commensal bacteria that are associated with colonization resistance against C. difficile. The initial screening tested the efficacy of eleven 2-AI molecules (compound 1 through 11 against C. difficile R20291 compared to a vancomycin (2 μg/ml control. Molecules were selected for their ability to inhibit C. difficile growth, toxin activity, and sporulation. Further testing included growth inhibition of other C. difficile strains (CD196, M68, CF5, 630, BI9, M120 belonging to distinct PCR ribotypes, and a commensal panel (Bacteroides fragilis, B. thetaiotaomicron, C. scindens, C. hylemonae, Lactobacillus acidophilus, L. gasseri, Escherichia coli, B. longum subsp. infantis. Three molecules compound 1 and 2, and 3 were microbicidal, whereas compounds 4, 7, 9, and 11 inhibited toxin activity without affecting the growth of C. difficile strains and the commensal microbiota. The antimicrobial and anti-toxin effects of 2-AI molecules need to be further characterized for mode of

Evolution of a recombinant (gucoamylase-producing) strain of Fusarium venenatum A3/5 in chemostat culture.

Science.gov (United States)

Wiebe, M G; Robson, G D; Shuster, J; Trinci, A P

2001-04-20

Fusarium venenatum JeRS 325 is a transformant of strain A3/5 which produces Aspergillus niger glucoamylase (GAM) under the control of a Fusarium oxysporum trypsin-like protease promoter. The evolution of JeRS 325 was studied in glucose-limited chemostat cultures grown on NaNO3 or (NH4)2SO4 as the nitrogen source. Thirteen mutants which were more highly branched and four mutants which were more sparsely branched than the parental strain were isolated from the NaNO3 chemostat. The highly branched mutants detected in this chemostat did not displace the sparsely branched population. The mutants isolated from the NaNO3 chemostat complemented representative strains previously isolated from glucose-limited chemostat cultures of F. venenatum A3/5 grown on (NH4)2SO4, but showed little complementation between themselves. By contrast, a highly branched mutant isolated from the (NH4)2SO4 chemostat culture displaced the sparsely branched mycelial population. None of the mutants isolated from the NaNO3 or (NH4)2SO4 chemostats produced as much GAM as JeRS 325. Southern blot analysis showed that all except one mutant had lost copies of both the glucoamylase and the acetamidase (the selectable marker) genes. However, specific GAM production was not necessarily correlated with the extent of glaA gene loss observed. Further, 10 of the mutants had lost the ability to grow on acetamide as the sole nitrogen source, although they retained copies of the amdS gene. In competition studies, mutants which could not utilize acetamide displaced mutants which could. The presence of foreign DNA in JeRS 325 resulted in a reduced specific growth rate (compared to A3/5), but the presence of the foreign DNA did not prevent the evolution of the strain or the isolation of mutants which had improved growth rates. Copyright 2001 John Wiley & Sons, Inc.

Extracellular polymeric substances (EPS) producing bacterial strains of municipal wastewater sludge: isolation, molecular identification, EPS characterization and performance for sludge settling and dewatering.

Science.gov (United States)

Bala Subramanian, S; Yan, S; Tyagi, R D; Surampalli, R Y

2010-04-01

Wastewater treatment plants often face the problems of sludge settling mainly due to sludge bulking. Generally, synthetic organic polymer and/or inorganic coagulants (ferric chloride, alum and quick lime) are used for sludge settling. These chemicals are very expensive and further pollute the environment. Whereas, the bioflocculants are environment friendly and may be used to flocculate the sludge. Extracellular polymeric substances (EPS) produced by sludge microorganisms play a definite role in sludge flocculation. In this study, 25 EPS producing strains were isolated from municipal wastewater treatment plant. Microorganisms were selected based on EPS production properties on solid agar medium. Three types of EPS (slime, capsular and bacterial broth mixture of both slime and capsular) were harvested and their characteristics were studied. EPS concentration (dry weight), viscosity and their charge (using a Zetaphoremeter) were also measured. Bioflocculability of obtained EPS was evaluated by measuring the kaolin clay flocculation activity. Six bacterial strains (BS2, BS8, BS9, BS11, BS15 and BS25) were selected based on the kaolin clay flocculation. The slime EPS was better for bioflocculation than capsular EPS and bacterial broth. Therefore, extracted slime EPS (partially purified) from six bacterial strains was studied in terms of sludge settling [sludge volume index (SVI)] and dewatering [capillary suction time (CST)]. Biopolymers produced by individual strains substantially improved dewaterability. The extracted slime EPS from six different strains were partially characterized. Copyright (c) 2009 Elsevier Ltd. All rights reserved.

The effect of rhamnolipid biosurfactant produced by Pseudomonas fluorescens on model bacterial strains and isolates from industrial wastewater.

Science.gov (United States)

Vasileva-Tonkova, Evgenia; Sotirova, Anna; Galabova, Danka

2011-02-01

In this study, the effect of rhamnolipid biosurfactant produced by Pseudomonas fluorescens on bacterial strains, laboratory strains, and isolates from industrial wastewater was investigated. It was shown that biosurfactant, depending on the concentration, has a neutral or detrimental effect on the growth and protein release of model Gram (+) strain Bacillus subtilis 168. The growth and protein release of model Gram (-) strain Pseudomonas aeruginosa 1390 was not influenced by the presence of biosurfactant in the medium. Rhamnolipid biosurfactant at the used concentrations supported the growth of some slow growing on hexadecane bacterial isolates, members of the microbial community. Changes in cell surface hydrophobicity and permeability of some Gram (+) and Gram (-) isolates in the presence of rhamnolipid biosurfactant were followed in experiments in vitro. It was found that bacterial cells treated with biosurfactant became more or less hydrophobic than untreated cells depending on individual characteristics and abilities of the strains. For all treated strains, an increase in the amount of released protein was observed with increasing the amount of biosurfactant, probably due to increased cell permeability as a result of changes in the organization of cell surface structures. The results obtained could contribute to clarify the relationships between members of the microbial community as well as suggest the efficiency of surface properties of rhamnolipid biosurfactant from Pseudomonas fluorescens making it potentially applicable in bioremediation of hydrocarbon-polluted environments.

Analysis of potential fumonisin-producing Fusarium species in corn products from three main maize-producing areas in eastern China.

Science.gov (United States)

Zhang, Liping; Wang, Jiansheng; Zhang, Chulong; Wang, Qiaomei

2013-02-01

Fusarium species are common fungal contaminants of maize and a number of them can produce mycotoxin fumonisins. China is one of the largest maize producers in the world. This study investigated the contamination of maize samples from three areas in eastern China by Fusarium and fumonisin-producing fungi as well as their fumonisin-producing potential. A total of 22 Fusarium strains were isolated, 19 of which were able to produce fumonisin. Among the 19 strains, 16 belonged to F. verticillioides, two to F. subglutinans and one to F. proliferatum. The majority (17/19) of the fumonisin-forming strains were high FB(1) producers, which is a potential health risk for the population in these areas. Fusarium contamination in samples from the mideastern area was the most serious (11 Fusarium strains, with nine producing fumonisin, isolated from 24 samples), followed by the northeastern area (nine Fusarium strains, with all nine producing fumonisin, isolated from 21 samples) and the southeastern area (two Fusarium strains, with one producing fumonisin, isolated from 19 samples). Although the overall levels of FBs and contamination by fumonisin-producing fungi in corn samples were not serious, the contaminating Fusarium strains possessed fairly strong toxicogenic ability and potential risk for food safety. Copyright © 2012 Society of Chemical Industry.

Structural characterization of bioengineered α-D-glucans produced by mutant glucansucrase GTF180 enzymes of lactobacillus reuteri strain 180

NARCIS (Netherlands)

Leeuwen, S.S. van; Kralj, S.; Eeuwema, W.; Gerwig, G.J.; Dijkhuizen, L.; Kamerling, J.P.

2009-01-01

Mutagenesis of specific amino acid residues of the glucansucrase (GTF180) enzyme from Lactobacillus reuteri strain 180 yielded 12 mutant enzymes that produced modified exopolysaccharides (mEPSs) from sucrose. Ethanol-precipitated and purified mEPSs were subjected to linkage analysis, Smith

Structural Characterization of Bioengineered alpha-D-Glucans Produced by Mutant Glucansucrase GTF180 Enzymes of Lactobacillus reuteri Strain 180

NARCIS (Netherlands)

van Leeuwen, Sander S.; Kralj, Slavko; Eeuwema, Wieger; Gerwig, Gerrit J.; Dijkhuizen, Lubbert; Kamerling, Johannis P.

Mutagenesis of specific amino acid residues of the glucansucrase (GTF180) enzyme from Lactobacillus reuteri strain 180 yielded 12 mutant enzymes that produced modified exopolysaccharides (mEPSs) from sucrose. Ethanol-precipitated and purified mEPSs were subjected to linkage analysis, Smith

Genetic segregation in a high-yielding streptomycin-producing strain of Streptomyces griseus.

Science.gov (United States)

Roth, M; Schwalenberg, B; Reiche, R; Noack, D; Geuther, R; Eritt, I

1982-01-01

The streptomycin-producing Streptomyces griseus HP spontaneously segregated non-reverting derivatives with altered phenotypes. Clones characterized by increased spore formation and decreased streptomycin production were found. Two other types of derivatives were defective in aerial mycelium and streptomycin formation as well, but differed in the capacity to synthesize a yellow pigment. These derivatives were examined with respect to further properties. The stability of S. griseus HP was investigated in relation to conditions of continuous culture. Both at 26 and 30 degrees C, under glycerol and NH4Cl limitation a rapid segregation and enrichment of streptomycin-non-producing derivatives occurred. At 34 degrees C and glycerol limitation segregation began only after about 35 generations of continuous culture. In NH4Cl-limited chemostats the original strain was stable during 80 generations. In the course of the continuous culture experiments it was shown that the onset of genetic segregation within mycelia can be detected before it becomes obvious in colonies grown from the mycelia. This was achieved by fractionation of the mycelia by protoplast formation and subsequent plating on regeneration medium allowing colony growth and differentiation.

OMG: Open Molecule Generator.

Science.gov (United States)

Peironcely, Julio E; Rojas-Chertó, Miguel; Fichera, Davide; Reijmers, Theo; Coulier, Leon; Faulon, Jean-Loup; Hankemeier, Thomas

2012-09-17

Computer Assisted Structure Elucidation has been used for decades to discover the chemical structure of unknown compounds. In this work we introduce the first open source structure generator, Open Molecule Generator (OMG), which for a given elemental composition produces all non-isomorphic chemical structures that match that elemental composition. Furthermore, this structure generator can accept as additional input one or multiple non-overlapping prescribed substructures to drastically reduce the number of possible chemical structures. Being open source allows for customization and future extension of its functionality. OMG relies on a modified version of the Canonical Augmentation Path, which grows intermediate chemical structures by adding bonds and checks that at each step only unique molecules are produced. In order to benchmark the tool, we generated chemical structures for the elemental formulas and substructures of different metabolites and compared the results with a commercially available structure generator. The results obtained, i.e. the number of molecules generated, were identical for elemental compositions having only C, O and H. For elemental compositions containing C, O, H, N, P and S, OMG produces all the chemically valid molecules while the other generator produces more, yet chemically impossible, molecules. The chemical completeness of the OMG results comes at the expense of being slower than the commercial generator. In addition to being open source, OMG clearly showed the added value of constraining the solution space by using multiple prescribed substructures as input. We expect this structure generator to be useful in many fields, but to be especially of great importance for metabolomics, where identifying unknown metabolites is still a major bottleneck.

OMG: Open Molecule Generator

Directory of Open Access Journals (Sweden)

Peironcely Julio E

2012-09-01

Full Text Available Abstract Computer Assisted Structure Elucidation has been used for decades to discover the chemical structure of unknown compounds. In this work we introduce the first open source structure generator, Open Molecule Generator (OMG, which for a given elemental composition produces all non-isomorphic chemical structures that match that elemental composition. Furthermore, this structure generator can accept as additional input one or multiple non-overlapping prescribed substructures to drastically reduce the number of possible chemical structures. Being open source allows for customization and future extension of its functionality. OMG relies on a modified version of the Canonical Augmentation Path, which grows intermediate chemical structures by adding bonds and checks that at each step only unique molecules are produced. In order to benchmark the tool, we generated chemical structures for the elemental formulas and substructures of different metabolites and compared the results with a commercially available structure generator. The results obtained, i.e. the number of molecules generated, were identical for elemental compositions having only C, O and H. For elemental compositions containing C, O, H, N, P and S, OMG produces all the chemically valid molecules while the other generator produces more, yet chemically impossible, molecules. The chemical completeness of the OMG results comes at the expense of being slower than the commercial generator. In addition to being open source, OMG clearly showed the added value of constraining the solution space by using multiple prescribed substructures as input. We expect this structure generator to be useful in many fields, but to be especially of great importance for metabolomics, where identifying unknown metabolites is still a major bottleneck.

Effect of γ-Aminobutyric Acid-producing Strain on Laying Performance, Egg Quality and Serum Enzyme Activity in Hy-Line Brown Hens under Heat Stress

Directory of Open Access Journals (Sweden)

Y. Z. Zhu

2015-07-01

Full Text Available Heat-stress remains a costly issue for animal production, especially for poultry as they lack sweat glands, and alleviating heat-stress is necessary for ensuring animal production in hot environment. A high γ-aminobutyric acid (GABA-producer Lactobacillus strain was used to investigate the effect of dietary GABA-producer on laying performance and egg quality in heat-stressed Hy-line brown hens. Hy-Line brown hens (n = 1,164 at 280 days of age were randomly divided into 4 groups based on the amount of freeze-dried GABA-producer added to the basal diet as follows: i 0 mg/kg, ii 25 mg/kg, iii 50 mg/kg, and iv 100 mg/kg. All hens were subjected to heat-stress treatment through maintaining the temperature and the relative humidity at 28.83±3.85°C and 37% to 53.9%, respectively. During the experiment, laying rate, egg weight and feed intake of hens were recorded daily. At the 30th and 60th day after the start of the experiment, biochemical parameters, enzyme activity and immune activity in serum were measured. Egg production, average egg weight, average daily feed intake, feed conversion ratio and percentage of speckled egg, soft shell egg and misshaped egg were significantly improved (p<0.05 by the increasing supplementation of the dietary GABA-producer. Shape index, eggshell thickness, strength and weight were increased linearly with increasing GABA-producer supplementation. The level of calcium, phosphorus, glucose, total protein and albumin in serum of the hens fed GABA-producing strain supplemented diet was significantly higher (p<0.05 than that of the hens fed the basal diet, whereas cholesterol level was decreased. Compared with the basal diet, GABA-producer strain supplementation increased serum level of glutathione peroxidase (p = 0.009 and superoxide dismutase. In conclusion, GABA-producer played an important role in alleviating heat-stress, the isolated GABA-producer strain might be a potential natural and safe probiotic to use to

Microstructure and Textural Properties of Yoghurts Produced by Exopolysaccharides- Producing Starter Cultures

DEFF Research Database (Denmark)

Zhang, Lanjun

conferred a ropy texture and resulted in yoghurts with decreased water holding capacity and an open microstructure. In addition, one of the LB strains with high amounts of EPS producing capacity improved water retention, when it was combined with an ST strain that produced negligible amounts of EPS...

Ultra-cold molecule production

International Nuclear Information System (INIS)

Ramirez-Serrano, Jamie; Chandler, David W.; Strecker, Kevin; Rahn, Larry A.

2005-01-01

The production of Ultra-cold molecules is a goal of many laboratories through out the world. Here we are pursuing a unique technique that utilizes the kinematics of atomic and molecular collisions to achieve the goal of producing substantial numbers of sub Kelvin molecules confined in a trap. Here a trap is defined as an apparatus that spatially localizes, in a known location in the laboratory, a sample of molecules whose temperature is below one degree absolute Kelvin. Further, the storage time for the molecules must be sufficient to measure and possibly further cool the molecules. We utilize a technique unique to Sandia to form cold molecules from near mass degenerate collisions between atoms and molecules. This report describes the progress we have made using this novel technique and the further progress towards trapping molecules we have cooled

Organic molecules with abnormal geometric parameters

International Nuclear Information System (INIS)

Komarov, Igor V

2001-01-01

Organic molecules, the structural parameters of which (carbon-carbon bond lengths, bond and torsion angles) differ appreciably from the typical most frequently encountered values, are discussed. Using many examples of 'record-breaking' molecules, the limits of structural distortions in carbon compounds and their unusual chemical properties are demonstrated. Particular attention is devoted to strained compounds not yet synthesised whose properties have been predicted using quantum-chemical calculations. Factors that ensure the stability of such compounds are outlined. The bibliography includes 358 references.

Complete genome sequence of Pseudomonas antarctica PAMC 27494, a bacteriocin-producing psychrophile isolated from Antarctica.

Science.gov (United States)

Lee, Jaejin; Cho, Yong-Joon; Yang, Jae Young; Jung, You-Jung; Hong, Soon Gyu; Kim, Ok-Sun

2017-10-10

Antimicrobial-producing, cold-adapted microorganisms have great potential for biotechnological applications in food, pharmaceutical, and cosmetic industries. Pseudomonas antarctica PAMC 27494, a psychrophile exhibiting antimicrobial activity, was isolated from an Antarctic freshwater sample. Here we report the complete genome of P. antarctica PAMC 27494. The strain contains a gene cluster encoding microcin B which inhibits DNA regulations by targeting the DNA gyrase. PAMC 27494 may produce R-type pyocins and also contains a complete set of proteins for the biosynthesis of adenosylcobalamin and possibly induces plant growth by supplying pyrroloquinoline quionone molecules. Copyright © 2017 Elsevier B.V. All rights reserved.

Study on breeding of daptomycin-producing strains by nitrogen ion implantation

International Nuclear Information System (INIS)

Zhou Jian; Liu Ying; Fang Dongsheng; Jiang Hong; Zhang Yin; Gao Wuyan

2008-01-01

Streptomyces roseosporus C20, the bacteria used in production of daptomycin, were implanted with (15-200)x10 13 /cm 2 of 20keV N + ions. Survival rate of the bacteria at different absorbed doses was investigated, and mutagenic effects of the microbe were studied. After breeding under the selection pressure of resistance to streptomycin (the lethal concentration is 1.2μg/mL), several mutant strains with higher yields of daptomycin have been obtained. One of mutant strains, N3-36, can increase up to 126% compared to the original strain. It also shows that the mutant strains have high genetic stability. (authors)

Activities of beta-lactam antibiotics against Escherichia coli strains producing extended-spectrum beta-lactamases.

Science.gov (United States)

Jacoby, G A; Carreras, I

1990-01-01

Seven extended-spectrum beta-lactamases related to TEM and four enzymes derived from SHV-1 were transferred to a common Escherichia coli host so that the activity of a variety of beta-lactams could be tested in a uniform genetic environment. For most derivatives, penicillinase activity was 10% or less than that of strains making TEM-1, TEM-2, or SHV-1 beta-lactamase, suggesting that reduced catalytic efficiency accompanied the broader substrate spectrum. Despite this deficit, resistance to aztreonam, carumonam, cefdinir, cefepime, cefixime, cefmenoxime, cefotaxime, cefotiam, cefpirome, cefpodoxime, ceftazidime, ceftibuten, ceftizoxime, ceftriaxone, cefuroxime, and E1040 was enhanced. For strains producing TEM-type enzymes, however, MICs of carumonam, cefepime, cefmenoxime, cefotiam, cefpirome, and ceftibuten were 8 micrograms/ml or less. Susceptibilities of cefmetazole, cefotetan, cefoxitin, flomoxef, imipenem, meropenem, moxalactam, temocillin, FCE 22101, and Sch 34343 were unaffected. FCE 22101, imipenem, meropenem, and Sch 34343 were inhibitory for all strains at 1 microgram/ml or less. In E. coli an OmpF- porin mutation in combination with an extended-spectrum beta-lactamase enhanced resistance to many of these agents, but generally by only fourfold. Hyperproduction of chromosomal AmpC beta-lactamase increased resistance to 7-alpha-methoxy beta-lactams but not that to temocillin. When tested at 8 micrograms/ml, clavulanate was more potent than sulbactam or tazobactam in overcoming resistance to ampicillin, while cefoperazone-sulbactam was more active than ticarcillin-clavulanate or piperacillin-tazobactam, especially against TEM-type extended-spectrum beta-lactamases. PMID:2193623

[Distiller Yeasts Producing Antibacterial Peptides].

Science.gov (United States)

Klyachko, E V; Morozkina, E V; Zaitchik, B Ts; Benevolensky, S V

2015-01-01

A new method of controlling lactic acid bacteria contamination was developed with the use of recombinant Saccharomyces cerevisiae strains producing antibacterial peptides. Genes encoding the antibacterial peptides pediocin and plantaricin with codons preferable for S. cerevisiae were synthesized, and a system was constructed for their secretory expression. Recombinant S. cerevisiae strains producing antibacterial peptides effectively inhibit the growth of Lactobacillus sakei, Pediacoccus pentasaceus, Pediacoccus acidilactici, etc. The application of distiller yeasts producing antibacterial peptides enhances the ethanol yield in cases of bacterial contamination. Recombinant yeasts producing the antibacterial peptides pediocin and plantaricin can successfully substitute the available industrial yeast strains upon ethanol production.

Selection and protein sds-page identification of a new high-producing polysaccharide strain of Spirulina platensis

International Nuclear Information System (INIS)

Wang Zhiping; Liu Yanhui

2004-01-01

The relationship between anti-radiation capacity and polysaccharide contents of ten Spirulina platensis strains were studied. The results showed that the correlation coefficient between 60 Co γ-ray half-lethal dose (LD 50 ) and polysaccharide contents of the 10 strains was 0.9873. After the single cells or spheroplasts of Sp-08 were treated by 0.6%EMS and 2.4 kGy 60 Co γ-ray irradiation, four morphological mutant named Sp-08A, Sp-08B, Sp-08C and Sp-08D, which could endure about 7.0 kGy γ-ray irradiation, were obtained. The polysaccharide contents of Sp-08A, Sp-08B, Sp-08C and Sp-08D, were 32.8%, 17.3%, 3.4% and 42.3% higher than that of their parent Sp-08, respectively. The results of protein SDS-PAGE analysis showed that the heredity of Sp-08A, Sp-08C and Sp-08D were mutated. Therefore, Sp-08A was a perfect high-producing polysaccharide strain with excellent characteristics of morphology and growth. Now, Sp-08A is applied in mass cultivation and industrialization. (authors)

Enzymic hydrolysis of xylans. I. A high xylanase and beta-xylosidase producing strain of Aspergillus niger

Energy Technology Data Exchange (ETDEWEB)

Conrad, D.

1981-01-01

Aspergillus niger, strain 110.42 (CBS) was selected as a producer of high xylanolytic activities. The time course of xylanase and beta-xylosidase production as well as the effect of pH and temperature on the activity of these enzymes were studied. High-performance liquid chromatography analysis of the enzymic degradation of arabinoxylan showed a nearly complete conversion to pentose sugars. Aspects of using crude xylanase preparations for enzymic saccharification of xylans are discussed.

Isolation and identification of a thermophilic strain producing trehalose synthase from geothermal water in China.

Science.gov (United States)

Zhu, Yueming; Zhang, Jun; Wei, Dongsheng; Wang, Yufan; Chen, Xiaoyun; Xing, Laijun; Li, Mingchun

2008-08-01

A slightly thermophilic strain, CBS-01, producing trehalose synthase (TreS), was isolated from geothermal water in this study. According to the phenotypic characteristics and phylogenetic analysis of the 16s rRNA gene sequence, it was identified as Meiothermus ruber. The trehalose synthase gene of Meiothermus ruber CBS-01 was cloned by polymerase chain reaction and sequenced. The TreS gene consisted of 2,895 nucleotides, which specified a 964-amino-acid protein. This novel TreS catalyzed reversible interconversion of maltose and trehalose.

Genealogy profiling through strain improvement by using metabolic network analysis: metabolic flux genealogy of several generations of lysine-producing corynebacteria.

Science.gov (United States)

Wittmann, Christoph; Heinzle, Elmar

2002-12-01

A comprehensive approach of metabolite balancing, (13)C tracer studies, gas chromatography-mass spectrometry, matrix-assisted laser desorption ionization-time of flight mass spectrometry, and isotopomer modeling was applied for comparative metabolic network analysis of a genealogy of five successive generations of lysine-producing Corynebacterium glutamicum. The five strains examined (C. glutamicum ATCC 13032, 13287, 21253, 21526, and 21543) were previously obtained by random mutagenesis and selection. Throughout the genealogy, the lysine yield in batch cultures increased markedly from 1.2 to 24.9% relative to the glucose uptake flux. Strain optimization was accompanied by significant changes in intracellular flux distributions. The relative pentose phosphate pathway (PPP) flux successively increased, clearly corresponding to the product yield. Moreover, the anaplerotic net flux increased almost twofold as a consequence of concerted regulation of C(3) carboxylation and C(4) decarboxylation fluxes to cover the increased demand for lysine formation; thus, the overall increase was a consequence of concerted regulation of C(3) carboxylation and C(4) decarboxylation fluxes. The relative flux through isocitrate dehydrogenase dropped from 82.7% in the wild type to 59.9% in the lysine-producing mutants. In contrast to the NADPH demand, which increased from 109 to 172% due to the increasing lysine yield, the overall NADPH supply remained constant between 185 and 196%, resulting in a decrease in the apparent NADPH excess through strain optimization. Extrapolated to industrial lysine producers, the NADPH supply might become a limiting factor. The relative contributions of PPP and the tricarboxylic acid cycle to NADPH generation changed markedly, indicating that C. glutamicum is able to maintain a constant supply of NADPH under completely different flux conditions. Statistical analysis by a Monte Carlo approach revealed high precision for the estimated fluxes, underlining the

Genotypic and Phylogenic Analysis of Lactobacilli Producing Bacteriocin Isolated from Traditional Dairy Products and Food

Directory of Open Access Journals (Sweden)

Frazaneh Tafvizi

2012-09-01

Full Text Available Background & Objective: Lactic acid bacteria (LAB are a group of Gram-positive, non-spore forming, cocci or rod shaped, catalase negative organisms, considered as Generally Recognized as Safe (GRAS organisms. These bacteria are used for thousands of years for production of fermented foods because of their ability to produce desirable changes in taste, flavor and texture. Different antimicrobial molecules such as bacteriocins produced by these bacteria that can inhibit food pathogens, so enhancing the shelf life and improving the safety of food products. Because of important role of LAB to improving the human health, molecular identification and phylogenic analysis of these bacteria based on 16S rRNA sequencing play the critical role in investigation of local sources of LAB in Iran. Materials & Methods: 5 isolates were selected from 20 isolates for molecular identification. These strains produced the high level of bacteriocin. Total genomic DNA was extracted by lysosyme extraction protocol. PCR-mediated amplification was carried out by degenerate primers. Sequencing was performed after purification of PCR product. Results: Isolates were deposited as novel strains of Lactobacillus casei and Entrococcus facium in GenBank. Conclusion: Because of high potential of local probiotic bacteria in Iran, these strains may be useful and could be used in the food industry.

Mechanical response of collagen molecule under hydrostatic compression

International Nuclear Information System (INIS)

Saini, Karanvir; Kumar, Navin

2015-01-01

Proteins like collagen are the basic building blocks of various body tissues (soft and hard). Collagen molecules find their presence in the skeletal system of the body where they bear mechanical loads from different directions, either individually or along with hydroxy-apatite crystals. Therefore, it is very important to understand the mechanical behavior of the collagen molecule which is subjected to multi-axial state of loading. The estimation of strains of collagen molecule along different directions resulting from the changes in hydrostatic pressure magnitude, can provide us new insights into its mechanical behavior. In the present work, full atomistic simulations have been used to study global (volumetric) as well as local (along different directions) mechanical properties of the hydrated collagen molecule which is subjected to different hydrostatic pressure magnitudes. To estimate the local mechanical properties, the strains of collagen molecule along its longitudinal and transverse directions have been acquired at different hydrostatic pressure magnitudes. In spite of non-homogeneous distribution of atoms within the collagen molecule, the calculated values of local mechanical properties have been found to carry the same order of magnitude along the longitudinal and transverse directions. It has been demonstrated that the values of global mechanical properties like compressibility, bulk modulus, etc. as well as local mechanical properties like linear compressibility, linear elastic modulus, etc. are functions of magnitudes of applied hydrostatic pressures. The mechanical characteristics of collagen molecule based on the atomistic model have also been compared with that of the continuum model in the present work. The comparison showed up orthotropic material behavior for the collagen molecule. The information on collagen molecule provided in the present study can be very helpful in designing the future bio-materials.

Mechanical response of collagen molecule under hydrostatic compression.

Science.gov (United States)

Saini, Karanvir; Kumar, Navin

2015-04-01

Proteins like collagen are the basic building blocks of various body tissues (soft and hard). Collagen molecules find their presence in the skeletal system of the body where they bear mechanical loads from different directions, either individually or along with hydroxy-apatite crystals. Therefore, it is very important to understand the mechanical behavior of the collagen molecule which is subjected to multi-axial state of loading. The estimation of strains of collagen molecule along different directions resulting from the changes in hydrostatic pressure magnitude, can provide us new insights into its mechanical behavior. In the present work, full atomistic simulations have been used to study global (volumetric) as well as local (along different directions) mechanical properties of the hydrated collagen molecule which is subjected to different hydrostatic pressure magnitudes. To estimate the local mechanical properties, the strains of collagen molecule along its longitudinal and transverse directions have been acquired at different hydrostatic pressure magnitudes. In spite of non-homogeneous distribution of atoms within the collagen molecule, the calculated values of local mechanical properties have been found to carry the same order of magnitude along the longitudinal and transverse directions. It has been demonstrated that the values of global mechanical properties like compressibility, bulk modulus, etc. as well as local mechanical properties like linear compressibility, linear elastic modulus, etc. are functions of magnitudes of applied hydrostatic pressures. The mechanical characteristics of collagen molecule based on the atomistic model have also been compared with that of the continuum model in the present work. The comparison showed up orthotropic material behavior for the collagen molecule. The information on collagen molecule provided in the present study can be very helpful in designing the future bio-materials. Copyright © 2015 Elsevier B.V. All rights

Mechanical response of collagen molecule under hydrostatic compression

Energy Technology Data Exchange (ETDEWEB)

Saini, Karanvir, E-mail: karans@iitrpr.ac.in; Kumar, Navin

2015-04-01

Proteins like collagen are the basic building blocks of various body tissues (soft and hard). Collagen molecules find their presence in the skeletal system of the body where they bear mechanical loads from different directions, either individually or along with hydroxy-apatite crystals. Therefore, it is very important to understand the mechanical behavior of the collagen molecule which is subjected to multi-axial state of loading. The estimation of strains of collagen molecule along different directions resulting from the changes in hydrostatic pressure magnitude, can provide us new insights into its mechanical behavior. In the present work, full atomistic simulations have been used to study global (volumetric) as well as local (along different directions) mechanical properties of the hydrated collagen molecule which is subjected to different hydrostatic pressure magnitudes. To estimate the local mechanical properties, the strains of collagen molecule along its longitudinal and transverse directions have been acquired at different hydrostatic pressure magnitudes. In spite of non-homogeneous distribution of atoms within the collagen molecule, the calculated values of local mechanical properties have been found to carry the same order of magnitude along the longitudinal and transverse directions. It has been demonstrated that the values of global mechanical properties like compressibility, bulk modulus, etc. as well as local mechanical properties like linear compressibility, linear elastic modulus, etc. are functions of magnitudes of applied hydrostatic pressures. The mechanical characteristics of collagen molecule based on the atomistic model have also been compared with that of the continuum model in the present work. The comparison showed up orthotropic material behavior for the collagen molecule. The information on collagen molecule provided in the present study can be very helpful in designing the future bio-materials.

[Genetic diversity of extraintestinal Escherichia coli strains producers of beta-lactamases TEM, SHV and CTX-M associated with healthcare].

Science.gov (United States)

Varela, Yasmin; Millán, Beatriz; Araque, María

2017-06-01

There are few reports from Venezuela describing the genetic basis that sustains the pathogenic potential and phylogenetics of Escherichia coli extraintestinal strains isolated in health care units. To establish the genetic diversity of extraintestinal E. coli strains producers of betalactamases TEM, SHV and CTX-M associated with healthcare. We studied a collection of 12 strains of extraintestinal E. coli with diminished sensitivity to broad-spectrum cephalosporins. Antimicrobial susceptibility was determined by minimum inhibitory concentration. We determined the phylogenetic groups, virulence factors and genes encoding antimicrobial resistance using PCR, and clonal characterization by repetitive element palindromic-PCR rep-PCR. All strains showed resistance to cephalosporins and joint resistance to quinolones and aminoglycosides. The phylogenetic distribution showed that the A and B1 groups were the most frequent, followed by D and B2. We found all the virulence factors analyzed in the B2 group, and fimH gene was the most frequent among them. We found blaCTX-M in all strains,with a higher prevalence of blaCTX-M-8; two of these strains showed coproduction of blaCTX-M-9 and were genetically identified as blaCTXM-65 and blaCTX-M-147 by sequencing. The strains under study showed genetic diversity, hosting a variety of virulence genes, as well as antimicrobial resistance with no particular phylogroup prevalence. This is the first report of blaCTX-M alleles in Venezuela and in the world associated to non-genetically related strains isolated in health care units, a situation that deserves attention, as well as the rationalization of antimicrobials use.

Bacillus amyloliquefaciens TSBSO 3.8, a biosurfactant-producing strain with biotechnological potential for microbial enhanced oil recovery.

Science.gov (United States)

Alvarez, Vanessa Marques; Jurelevicius, Diogo; Marques, Joana Montezano; de Souza, Pamella Macedo; de Araújo, Livia Vieira; Barros, Thalita Gonçalves; de Souza, Rodrigo Octavio Mendonça Alves; Freire, Denise Maria Guimarães; Seldin, Lucy

2015-12-01

A screening for biosurfactant-producing bacteria was conducted with 217 strains that were isolated from environmental samples contaminated with crude oil and/or petroleum derivatives. Although 19 promising biosurfactant producers were detected, strain TSBSO 3.8, which was identified by molecular methods as Bacillus amyloliquefaciens, drew attention for its production of a high-activity compound that presented an emulsification activity of 63% and considerably decreased surface (28.5 mN/m) and interfacial (11.4 mN/m) tensions in Trypticase Soy Broth culture medium. TSBSO 3.8 growth and biosurfactant production were tested under different physical and chemical conditions to evaluate its biotechnological potential. Biosurfactant production occurred between 0.5% and 7% NaCl, at pH values varying from 6 to 9 and temperatures ranging from 28 to 50 °C. Moreover, biosurfactant properties remained the same after autoclaving at 121 °C for 15 min. The biosurfactant was also successful in a test to simulate microbial enhanced oil recovery (MEOR). Mass spectrometry analysis showed that the surface active compound was a surfactin, known as a powerful biosurfactant that is commonly produced by Bacillus species. The production of a high-efficiency biosurfactant, under some physical and chemical conditions that resemble those experienced in an oil production reservoir, such as high salinities and temperatures, makes TSBSO 3.8 an excellent candidate and creates good expectations for its application in MEOR. Copyright © 2015 Elsevier B.V. All rights reserved.

Effect of γ-Aminobutyric Acid-producing Lactobacillus Strain on Laying Performance, Egg Quality and Serum Enzyme Activity in Hy-Line Brown Hens under Heat Stress.

Science.gov (United States)

Zhu, Y Z; Cheng, J L; Ren, M; Yin, L; Piao, X S

2015-07-01

Heat-stress remains a costly issue for animal production, especially for poultry as they lack sweat glands, and alleviating heat-stress is necessary for ensuring animal production in hot environment. A high γ-aminobutyric acid (GABA)-producer Lactobacillus strain was used to investigate the effect of dietary GABA-producer on laying performance and egg quality in heat-stressed Hy-line brown hens. Hy-Line brown hens (n = 1,164) at 280 days of age were randomly divided into 4 groups based on the amount of freeze-dried GABA-producer added to the basal diet as follows: i) 0 mg/kg, ii) 25 mg/kg, iii) 50 mg/kg, and iv) 100 mg/kg. All hens were subjected to heat-stress treatment through maintaining the temperature and the relative humidity at 28.83±3.85°C and 37% to 53.9%, respectively. During the experiment, laying rate, egg weight and feed intake of hens were recorded daily. At the 30th and 60th day after the start of the experiment, biochemical parameters, enzyme activity and immune activity in serum were measured. Egg production, average egg weight, average daily feed intake, feed conversion ratio and percentage of speckled egg, soft shell egg and misshaped egg were significantly improved (pGABA-producer. Shape index, eggshell thickness, strength and weight were increased linearly with increasing GABA-producer supplementation. The level of calcium, phosphorus, glucose, total protein and albumin in serum of the hens fed GABA-producing strain supplemented diet was significantly higher (plevel was decreased. Compared with the basal diet, GABA-producer strain supplementation increased serum level of glutathione peroxidase (p = 0.009) and superoxide dismutase. In conclusion, GABA-producer played an important role in alleviating heat-stress, the isolated GABA-producer strain might be a potential natural and safe probiotic to use to improve laying performance and egg quality in heat-stressed hens.

A new class of IMP dehydrogenase with a role in self-resistance of mycophenolic acid producing fungi

Directory of Open Access Journals (Sweden)

Mortensen Uffe H

2011-09-01

Full Text Available Abstract Background Many secondary metabolites produced by filamentous fungi have potent biological activities, to which the producer organism must be resistant. An example of pharmaceutical interest is mycophenolic acid (MPA, an immunosuppressant molecule produced by several Penicillium species. The target of MPA is inosine-5'-monophosphate dehydrogenase (IMPDH, which catalyses the rate limiting step in the synthesis of guanine nucleotides. The recent discovery of the MPA biosynthetic gene cluster from Penicillium brevicompactum revealed an extra copy of the IMPDH-encoding gene (mpaF embedded within the cluster. This finding suggests that the key component of MPA self resistance is likely based on the IMPDH encoded by mpaF. Results In accordance with our hypothesis, heterologous expression of mpaF dramatically increased MPA resistance in a model fungus, Aspergillus nidulans, which does not produce MPA. The growth of an A. nidulans strain expressing mpaF was only marginally affected by MPA at concentrations as high as 200 μg/ml. To further substantiate the role of mpaF in MPA resistance, we searched for mpaF orthologs in six MPA producer/non-producer strains from Penicillium subgenus Penicillium. All six strains were found to hold two copies of IMPDH. A cladistic analysis based on the corresponding cDNA sequences revealed a novel group constituting mpaF homologs. Interestingly, a conserved tyrosine residue in the original class of IMPDHs is replaced by a phenylalanine residue in the new IMPDH class. Conclusions We identified a novel variant of the IMPDH-encoding gene in six different strains from Penicillium subgenus Penicillium. The novel IMPDH variant from MPA producer P. brevicompactum was shown to confer a high degree of MPA resistance when expressed in a non-producer fungus. Our study provides a basis for understanding the molecular mechanism of MPA resistance and has relevance for biotechnological and pharmaceutical applications.

A hydrogen-producing, hydrogenase-free mutant strain of Nostoc punctiforme ATCC 29133

Energy Technology Data Exchange (ETDEWEB)

Lindberg, P.; Lindblad, P. [Uppsala Univ. (Sweden). Dept. of Physiological Botany; Schuetz, K.; Happe, T. [Universitaet Bonn (Germany). Botanisches Inst.

2002-12-01

The hupL gene, encoding the uptake hydrogenase large subunit, in Nostoc sp. strain ATCC 29133, a strain lacking a bidirectional hydrogenase, was inactivated by insertional mutagenesis. Recombinant strains were isolated and analysed, and one hupL{sup -} strain, NHM5, was selected for further study. Cultures of NHM5 were grown under nitrogen-fixing conditions and H{sub 2} evolution under air was observed using an H{sub 2} electrode. (Author)

Comparative evaluation of the Ridascreen Verotoxin enzyme immunoassay for detection of Shiga-toxin producing strains of Escherichia coli (STEC) from food and other sources.

Science.gov (United States)

Beutin, L; Steinrück, H; Krause, G; Steege, K; Haby, S; Hultsch, G; Appel, B

2007-03-01

To evaluate the suitability of the commercially distributed Ridascreen Verotoxin enzyme immunoassay (EIA) for detection of known genetic types of the Vero (Shiga) toxins 1 (Stx1) and 2 (Stx2) families and to determine its relative sensitivity and specificity. The Ridascreen-EIA was compared with the Vero cell assay, a P(1)-glycoprotein receptor EIA and with stx gene-specific PCs for detection of Stx with 43 Shiga toxin-producing strains of Escherichia coli (STEC) reference strains and with 241 test strains. The Ridascreen-EIA detects strains producing Stx1 and variants Stx1c and Stx1d, as well as Stx2 and variants Stx2d1, Stx2d2, Stx2e, Stx2d, Stx2-O118 (Stx2d-ount), Stx2-NV206, Stx2f and Stx2g. The assay showed a relative sensitivity of 95.7% and a relative specificity of 98.7%. Some of the Stx2-O118-, Stx2e- and Stx2g-producing STEC were not detected with the Ridascreen-EIA probably because of low amount of toxin produced by these strains. The Ridascreen-EIA is able to detect all known types of Stx and is applicable for routine screening of bacterial isolates owing to its high specificity. It is less applicable for testing samples where low amounts of Stx are expected, such as mixed cultures and certain Stx2 variants. This study presents a first comprehensive evaluation of the Ridascreen-EIA, a rapid standardized STEC screening test for routine diagnostic laboratories. Data are presented on the type of the spectrum of Stx that are detected with this immunoassay and its advantages and limits for practical use.

A Pressure Test to Make 10 Molecules in 90 Days: External Evaluation of Methods to Engineer Biology.

Science.gov (United States)

Casini, Arturo; Chang, Fang-Yuan; Eluere, Raissa; King, Andrew M; Young, Eric M; Dudley, Quentin M; Karim, Ashty; Pratt, Katelin; Bristol, Cassandra; Forget, Anthony; Ghodasara, Amar; Warden-Rothman, Robert; Gan, Rui; Cristofaro, Alexander; Borujeni, Amin Espah; Ryu, Min-Hyung; Li, Jian; Kwon, Yong-Chan; Wang, He; Tatsis, Evangelos; Rodriguez-Lopez, Carlos; O'Connor, Sarah; Medema, Marnix H; Fischbach, Michael A; Jewett, Michael C; Voigt, Christopher; Gordon, D Benjamin

2018-03-28

Centralized facilities for genetic engineering, or "biofoundries", offer the potential to design organisms to address emerging needs in medicine, agriculture, industry, and defense. The field has seen rapid advances in technology, but it is difficult to gauge current capabilities or identify gaps across projects. To this end, our foundry was assessed via a timed "pressure test", in which 3 months were given to build organisms to produce 10 molecules unknown to us in advance. By applying a diversity of new approaches, we produced the desired molecule or a closely related one for six out of 10 targets during the performance period and made advances toward production of the others as well. Specifically, we increased the titers of 1-hexadecanol, pyrrolnitrin, and pacidamycin D, found novel routes to the enediyne warhead underlying powerful antimicrobials, established a cell-free system for monoterpene production, produced an intermediate toward vincristine biosynthesis, and encoded 7802 individually retrievable pathways to 540 bisindoles in a DNA pool. Pathways to tetrahydrofuran and barbamide were designed and constructed, but toxicity or analytical tools inhibited further progress. In sum, we constructed 1.2 Mb DNA, built 215 strains spanning five species ( Saccharomyces cerevisiae, Escherichia coli, Streptomyces albidoflavus, Streptomyces coelicolor, and Streptomyces albovinaceus), established two cell-free systems, and performed 690 assays developed in-house for the molecules.

Effects of sub-lethal high-pressure homogenization treatment on the outermost cellular structures and the volatile-molecule profiles of two strains of probiotic lactobacilli.

Science.gov (United States)

Tabanelli, Giulia; Vernocchi, Pamela; Patrignani, Francesca; Del Chierico, Federica; Putignani, Lorenza; Vinderola, Gabriel; Reinheimer, Jorge A; Gardini, Fausto; Lanciotti, Rosalba

2015-01-01

Applying sub-lethal levels of high-pressure homogenization (HPH) to lactic acid bacteria has been proposed as a method of enhancing some of their functional properties. Because the principal targets of HPH are the cell-surface structures, the aim of this study was to examine the effect of sub-lethal HPH treatment on the outermost cellular structures and the proteomic profiles of two known probiotic bacterial strains. Moreover, the effect of HPH treatment on the metabolism of probiotic cells within a dairy product during its refrigerated storage was investigated using SPME-GC-MS. Transmission electron microscopy was used to examine the microstructural changes in the outermost cellular structures due to HPH treatment. These alterations may be involved in the changes in some of the technological and functional properties of the strains that were observed after pressure treatment. Moreover, the proteomic profiles of the probiotic strains treated with HPH and incubated at 37°C for various periods showed different peptide patterns compared with those of the untreated cells. In addition, there were differences in the peaks that were observed in the low-mass spectral region (2000-3000 Da) of the spectral profiles of the control and treated samples. Due to pressure treatment, the volatile-molecule profiles of buttermilk inoculated with treated or control cells and stored at 4°C for 30 days exhibited overall changes in the aroma profile and in the production of molecules that improved its sensory profile, although the two different species imparted specific fingerprints to the product. The results of this study will contribute to understanding the changes that occur in the outermost cellular structures and the metabolism of LAB in response to HPH treatment. The findings of this investigation may contribute to elucidating the relationships between these changes and the alterations of the technological and functional properties of LAB induced by pressure treatment.

Screening and Evaluation of Polyhydroxybutyrate-Producing Strains from Indigenous Isolate Cupriavidus taiwanensis Strains

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Om-Murugan Janarthanan

2011-01-01

Full Text Available Polyhydroxyalkanoate (PHA is a biodegradable material with many potential biomedical applications, including medical implants and drug delivery. This study developed a system for screening production strains in order to optimize PHA production in Cupriavidus taiwanensis 184, 185, 186, 187, 204, 208, 209 and Pseudomona oleovorans ATCC 29347. In this study, Sudan black B staining, Infrared (IR and Gas Chromatography (GC analysis indicated that the best strain for PHA synthesis is C. taiwanensis 184, which obtains polyhydroxybutyrate (PHB. Cultivation of C. taiwanensis 184 under a pH of 7.0, at 30 °C, and at an agitation rate of 200 rpm, obtained a PHB content of 10% and PHB production of 0.14 g/L. The carbon and nitrogen types selected for analysis of PHB production by C. taiwanensis 184 were gluconic acid and NH4Cl, respectively. Optimal carbon/nitrogen ratio for PHB production was also determined. This study demonstrated a PHB content of 58.81% and a PHB production of 2.44 g/L when the carbon/nitrogen ratio of 8/1 was selected for C. taiwanensis 184. A two‑stage fermentation strategy significantly enhanced PHB content and PHB production. Under a two-stage fermentation strategy with nutrient‑limited conditions, C. taiwanensis 184 obtained a PHB content of 72% and a PHB concentration of 7 g/L. Finally, experimental results confirmed that optimizing the growth medium and fermentation conditions for cultivating the indigenous C. taiwanensis 184 strain substantially elevated PHB content from 10% to 72% and PHB production from 0.14 g/L to 7 g/L, respectively.

Strain-dependent Damage in Mouse Lung After Carbon Ion Irradiation

Energy Technology Data Exchange (ETDEWEB)

Moritake, Takashi [Advanced Radiation Biology Research Program, Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba (Japan); Proton Medical Research Center, University of Tsukuba, Tsukuba (Japan); Fujita, Hidetoshi; Yanagisawa, Mitsuru; Nakawatari, Miyako; Imadome, Kaori; Nakamura, Etsuko; Iwakawa, Mayumi [Advanced Radiation Biology Research Program, Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba (Japan); Imai, Takashi, E-mail: imait@nirs.go.jp [Advanced Radiation Biology Research Program, Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba (Japan)

2012-09-01

Purpose: To examine whether inherent factors produce differences in lung morbidity in response to carbon ion (C-ion) irradiation, and to identify the molecules that have a key role in strain-dependent adverse effects in the lung. Methods and Materials: Three strains of female mice (C3H/He Slc, C57BL/6J Jms Slc, and A/J Jms Slc) were locally irradiated in the thorax with either C-ion beams (290 MeV/n, in 6 cm spread-out Bragg peak) or with {sup 137}Cs {gamma}-rays as a reference beam. We performed survival assays and histologic examination of the lung with hematoxylin-eosin and Masson's trichrome staining. In addition, we performed immunohistochemical staining for hyaluronic acid (HA), CD44, and Mac3 and assayed for gene expression. Results: The survival data in mice showed a between-strain variance after C-ion irradiation with 10 Gy. The median survival time of C3H/He was significantly shortened after C-ion irradiation at the higher dose of 12.5 Gy. Histologic examination revealed early-phase hemorrhagic pneumonitis in C3H/He and late-phase focal fibrotic lesions in C57BL/6J after C-ion irradiation with 10 Gy. Pleural effusion was apparent in C57BL/6J and A/J mice, 168 days after C-ion irradiation with 10 Gy. Microarray analysis of irradiated lung tissue in the three mouse strains identified differential expression changes in growth differentiation factor 15 (Gdf15), which regulates macrophage function, and hyaluronan synthase 1 (Has1), which plays a role in HA metabolism. Immunohistochemistry showed that the number of CD44-positive cells, a surrogate marker for HA accumulation, and Mac3-positive cells, a marker for macrophage infiltration in irradiated lung, varied significantly among the three mouse strains during the early phase. Conclusions: This study demonstrated a strain-dependent differential response in mice to C-ion thoracic irradiation. Our findings identified candidate molecules that could be implicated in the between-strain variance to early

Different response to acetic acid stress in Saccharomyces cerevisiae wild-type and l-ascorbic acid-producing strains.

Science.gov (United States)

Martani, Francesca; Fossati, Tiziana; Posteri, Riccardo; Signori, Lorenzo; Porro, Danilo; Branduardi, Paola

2013-09-01

Biotechnological processes are of increasing significance for industrial production of fine and bulk chemicals, including biofuels. Unfortunately, under operative conditions microorganisms meet multiple stresses, such as non-optimal pH, temperature, oxygenation and osmotic stress. Moreover, they have to face inhibitory compounds released during the pretreatment of lignocellulosic biomasses, which constitute the preferential substrate for second-generation processes. Inhibitors include furan derivatives, phenolic compounds and weak organic acids, among which acetic acid is one of the most abundant and detrimental for cells. They impair cellular metabolism and growth, reducing the productivity of the process: therefore, the development of robust cell factories with improved production rates and resistance is of crucial importance. Here we show that a yeast strain engineered to endogenously produce vitamin C exhibits an increased tolerance compared to the parental strain when exposed to acetic acid at moderately toxic concentrations, measured as viability on plates. Starting from this evidence, we investigated more deeply: (a) the nature and levels of reactive oxygen species (ROS); (b) the activation of enzymes that act directly as detoxifiers of reactive oxygen species, such as superoxide dismutase (SOD) and catalase, in parental and engineered strains during acetic acid stress. The data indicate that the engineered strain can better recover from stress by limiting ROS accumulation, independently from SOD activation. The engineered yeast can be proposed as a model for further investigating direct and indirect mechanism(s) by which an antioxidant can rescue cells from organic acid damage; moreover, these studies will possibly provide additional targets for further strain improvements. Copyright © 2013 John Wiley & Sons, Ltd.

Genetic characterization of Shiga toxin-producing Escherichia coli O26:H11 strains isolated from animal, food, and clinical samples

Science.gov (United States)

Krüger, Alejandra; Lucchesi, Paula M. A.; Sanso, A. Mariel; Etcheverría, Analía I.; Bustamante, Ana V.; Burgán, Julia; Fernández, Luciana; Fernández, Daniel; Leotta, Gerardo; Friedrich, Alexander W.; Padola, Nora L.; Rossen, John W. A.

2015-01-01

The Shiga-toxin producing Escherichia coli (STEC) may cause serious illness in human. Here we analyze O26:H11 strains known to be among the most reported STEC strains causing human infections. Genetic characterization of strains isolated from animal, food, and clinical specimens in Argentina showed that most carried either stx1a or stx2a subtypes. Interestingly, stx2a-positive O26:H11 rarely isolated from cattle in other countries showed to be an important proportion of O26:H11 strains circulating in cattle and food in our region. Seventeen percent of the isolates harbored more than one gene associated with antimicrobial resistance. In addition to stx, all strains contained the virulence genes eae-β, tir, efa, iha, espB, cif, espA, espF, espJ, nleA, nleB, nleC, and iss; and all except one contained ehxA, espP, and cba genes. On the other hand, toxB and espI genes were exclusively observed in stx2-positive isolates, whereas katP was only found in stx1a-positive isolates. Our results show that O26:H11 STEC strains circulating in Argentina, including those isolated from humans, cattle, and meat products, present a high pathogenic potential, and evidence that cattle can be a reservoir of O26:H11 strains harboring stx2a. PMID:26539413

Engineering control of bacterial cellulose production using a genetic toolkit and a new cellulose-producing strain

Science.gov (United States)

Florea, Michael; Hagemann, Henrik; Santosa, Gabriella; Micklem, Chris N.; Spencer-Milnes, Xenia; de Arroyo Garcia, Laura; Paschou, Despoina; Lazenbatt, Christopher; Kong, Deze; Chughtai, Haroon; Jensen, Kirsten; Freemont, Paul S.; Kitney, Richard; Reeve, Benjamin; Ellis, Tom

2016-01-01

Bacterial cellulose is a strong and ultrapure form of cellulose produced naturally by several species of the Acetobacteraceae. Its high strength, purity, and biocompatibility make it of great interest to materials science; however, precise control of its biosynthesis has remained a challenge for biotechnology. Here we isolate a strain of Komagataeibacter rhaeticus (K. rhaeticus iGEM) that can produce cellulose at high yields, grow in low-nitrogen conditions, and is highly resistant to toxic chemicals. We achieved external control over its bacterial cellulose production through development of a modular genetic toolkit that enables rational reprogramming of the cell. To further its use as an organism for biotechnology, we sequenced its genome and demonstrate genetic circuits that enable functionalization and patterning of heterologous gene expression within the cellulose matrix. This work lays the foundations for using genetic engineering to produce cellulose-based materials, with numerous applications in basic science, materials engineering, and biotechnology. PMID:27247386

Comparison of the virulence of exopolysaccharide-producing Prevotella intermedia to exopolysaccharide non-producing periodontopathic organisms.

Science.gov (United States)

Yamanaka, Takeshi; Yamane, Kazuyoshi; Furukawa, Tomoyo; Matsumoto-Mashimo, Chiho; Sugimori, Chieko; Nambu, Takayuki; Obata, Noboru; Walker, Clay B; Leung, Kai-Poon; Fukushima, Hisanori

2011-08-25

Evidence in the literature suggests that exopolysaccharides (EPS) produced by bacterial cells are essential for the expression of virulence in these organisms. Secreted EPSs form the framework in which microbial biofilms are built. This study evaluates the role of EPS in Prevotella intermedia for the expression of virulence. This evaluation was accomplished by comparing EPS-producing P. intermedia strains 17 and OD1-16 with non-producing P. intermedia ATCC 25611 and Porphyromonas gingivalis strains ATCC 33277, 381 and W83 for their ability to induce abscess formation in mice and evade phagocytosis. EPS-producing P. intermedia strains 17 and OD1-16 induced highly noticeable abscess lesions in mice at 107 colony-forming units (CFU). In comparison, P. intermedia ATCC 25611 and P. gingivalis ATCC 33277, 381 and W83, which all lacked the ability to produce viscous materials, required 100-fold more bacteria (109 CFU) in order to induce detectable abscess lesions in mice. Regarding antiphagocytic activity, P. intermedia strains 17 and OD1-16 were rarely internalized by human polymorphonuclear leukocytes, but other strains were readily engulfed and detected in the phagosomes of these phagocytes. These results demonstrate that the production of EPS by P. intermedia strains 17 and OD1-16 could contribute to the pathogenicity of this organism by conferring their ability to evade the host's innate defence response.

Detection of Quorum Sensing Activity in the Multidrug-Resistant Clinical Isolate Pseudomonas aeruginosa Strain GB11

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Huey Jia Cheng

2014-07-01

Full Text Available A multidrug-resistant clinical bacteria strain GB11 was isolated from a wound swab on the leg of a patient. Identity of stain GB11 as Pseudomonas aeruginosa was validated by using matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS. Detection of the production of signaling molecules, N-acylhomoserine lactones (AHLs, was conducted using three different bacterial biosensors. A total of four different AHLs were found to be produced by strain GB11, namely N-butyryl homoserine lactone (C4-HSL, N-hexanoylhomoserine lactone (C6-HSL, N-octanoyl homoserine lactone (C8-HSL and N-3-oxo-dodecanoylhomoserine lactone (3-oxo-C12-HSL using high resolution liquid chromatography tandem mass spectrometry (LC-MS/MS. Of these detected AHLs, 3-oxo-C12-HSL was found to be the most abundant AHL produced by P. aeruginosa GB11.

Case of Meningitis in a Neonate Caused by an Extended-Spectrum-Beta-Lactamase-Producing Strain of Hypervirulent Klebsiella pneumoniae

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Khalit S. Khaertynov

2017-08-01

Full Text Available Klebsiella pneumoniae is one of the most important infectious agents among neonates. This pathogen has a potential to develop an increased antimicrobial resistance and virulence. The classic non-virulent strain of K. pneumoniae, producing an extended-spectrum beta-lactamases (ESBL, is associated with nosocomial infection mainly in preterm neonates. Hypervirulent K. pneumoniae strains are associated with invasive infection among previously healthy ambulatory patients, and most of them exhibit antimicrobial susceptibility. During the last few years, several cases of diseases caused by hypervirulent K. pneumoniae producing ESBL have been registered in different geographical regions of the world. However, reports of such cases in neonates are rare. Here, we reported that this pathogen can cause pyogenic meningitis in full-term neonate with poor prognosis. A previously healthy, full-term, 12-day-old neonate was admitted to the infectious diseases hospital with suspected meningitis. The clinical symptoms included loss of appetite, irritability, fever, seizures, and a bulging anterior fontanelle. The analysis of the cerebrospinal fluid confirmed the diagnosis of meningitis. Blood and cerebrospinal fluid cultures were positive for K. pneumoniae, producing ESBL. K. pneumoniae isolates were resistant to aminopenicillins, 3rd generation cephalosporins but were sensitive to imipenem and meropenem. The “string test” was positive. The study of the virulence factors of K. pneumoniae by PCR revealed the presence of the rmpA gene. A combination of K. pneumoniae virulence and drug resistance complicated by cerebral oedema led to the death of the neonate. We concluded that both the risk of developing severe forms of infection and the outcome of the disease due to K. pneumonia are associated with the phenotypic features of the pathogen such as its antibiotic susceptibility and virulence factors. Emergence of the ESBL-producing strain of hypervirulent K

Isolation and Molecular Characterization of Biofouling Bacteria and Profiling of Quorum Sensing Signal Molecules from Membrane Bioreactor Activated Sludge

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Harshad Lade

2014-02-01

Full Text Available The formation of biofilm in a membrane bioreactor depends on the production of various signaling molecules like N-acyl homoserine lactones (AHLs. In the present study, a total of 200 bacterial strains were isolated from membrane bioreactor activated sludge and screened for AHLs production using two biosensor systems, Chromobacterium violaceum CV026 and Agrobacterium tumefaciens A136. A correlation between AHLs production and biofilm formation has been made among screened AHLs producing strains. The 16S rRNA gene sequence analysis revealed the dominance of Aeromonas and Enterobacter sp. in AHLs production; however few a species of Serratia, Leclercia, Pseudomonas, Klebsiella, Raoultella and Citrobacter were also identified. The chromatographic characterization of sludge extract showed the presence of a broad range of quorum sensing signal molecules. Further identification of sludge AHLs by thin layer chromatography bioassay and high performance liquid chromatography confirms the presence of C4-HSL, C6-HSL, C8-HSL, 3-oxo-C8-HSL, C10-HSL, C12-HSL, 3-oxo-C12-HSL and C14-HSL. The occurrence of AHLs in sludge extract and dominance of Aeromonas and Enterobacter sp. in activated sludge suggests the key role of these bacterial strains in AHLs production and thereby membrane fouling.

Isolation and molecular characterization of biofouling bacteria and profiling of quorum sensing signal molecules from membrane bioreactor activated sludge.

Science.gov (United States)

Lade, Harshad; Paul, Diby; Kweon, Ji Hyang

2014-02-04

The formation of biofilm in a membrane bioreactor depends on the production of various signaling molecules like N-acyl homoserine lactones (AHLs). In the present study, a total of 200 bacterial strains were isolated from membrane bioreactor activated sludge and screened for AHLs production using two biosensor systems, Chromobacterium violaceum CV026 and Agrobacterium tumefaciens A136. A correlation between AHLs production and biofilm formation has been made among screened AHLs producing strains. The 16S rRNA gene sequence analysis revealed the dominance of Aeromonas and Enterobacter sp. in AHLs production; however few a species of Serratia, Leclercia, Pseudomonas, Klebsiella, Raoultella and Citrobacter were also identified. The chromatographic characterization of sludge extract showed the presence of a broad range of quorum sensing signal molecules. Further identification of sludge AHLs by thin layer chromatography bioassay and high performance liquid chromatography confirms the presence of C4-HSL, C6-HSL, C8-HSL, 3-oxo-C8-HSL, C10-HSL, C12-HSL, 3-oxo-C12-HSL and C14-HSL. The occurrence of AHLs in sludge extract and dominance of Aeromonas and Enterobacter sp. in activated sludge suggests the key role of these bacterial strains in AHLs production and thereby membrane fouling.

Genome Sequence Analysis of the Biogenic Amine-Producing Strain Lactococcus lactis subsp. cremoris CECT 8666 (Formerly GE2-14)

Science.gov (United States)

del Rio, Beatriz; Linares, Daniel M.; Fernandez, Maria; Mayo, Baltasar; Martin, M. Cruz; Alvarez, Miguel A.

2014-01-01

We here report a 2,801,031-bp annotated draft assembly for the Lactococcus lactis subsp. cremoris GE2-14 genome. This dairy strain produces the biogenic amine putrescine. This sequence may help identify the mechanisms regulating putrescine biosynthesis and throw light on ways to reduce its presence in fermented foods. PMID:25342694

Millimeterwave spectroscopy of transient molecules produced in a ...

Indian Academy of Sciences (India)

produced inside the cell in a low pressure DC discharge of precursor gases. ... SO radical was also produced outside the cell by reactions of discharged oxygen .... have been reported by Dodd and Little [15] who have also calculated force.

Bacteriocin producers from traditional food products

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Thonart P.

2007-01-01

Full Text Available A total of 220 strains of LAB isolated from 32 samples of traditional fermented food from Senegal were screened for bacteriocin production. Two bacteriocin producers, Lactococcus lactis subsp. lactis and Enterococcus faecium, were identified from 12 bacteriocin-producing isolates on the basis of phenotypic analyses and 16S rDNA sequence. Both bacteriocins produced by new isolates show antimicrobial activity against Listeria monocytogenes and Bacillus coagulans whereas only that produced by Lactococcus lactis has an activity against Bacillus cereus. Bacteriocin-producing Lactococcus lactis strains were found in a variety of traditional foods indicating a high potential of growth of this strain in variable ecological complex environment. Partial 16S rDNA of the two bacteriocin producers obtained in this study has been registered to Genbank databases under the accession number AY971748 for Lactococcus lactis subsp. lactis (named CWBI-B1410 and AY971749 for Enterococcus faecium (named CWBI-B1411. The new bacteriocin-producing Lactococcus lactis subsp. lactis strain has been selected for identification and application of the bacteriocin to food preservation.

Quantitative analysis of the lactic acid and acetaldehyde produced by Streptococcus thermophilus and Lactobacillus bulgaricus strains isolated from traditional Turkish yogurts using HPLC.

Science.gov (United States)

Gezginc, Y; Topcal, F; Comertpay, S; Akyol, I

2015-03-01

The present study was conducted to evaluate the lactic acid- and acetaldehyde-producing abilities of lactic acid bacterial species isolated from traditionally manufactured Turkish yogurts using HPLC. The lactic acid bacterial species purified from the yogurts were the 2 most widely used species in industrial yogurt production: Streptococcus thermophilus and Lactobacillus bulgaricus. These bacteria have the ability to ferment hexose sugars homofermentatively to generate lactic acid and some carbonyl compounds, such as acetaldehyde through pyruvate metabolism. The levels of the compounds produced during fermentation influence the texture and the flavor of the yogurt and are themselves influenced by the chemical composition of the milk, processing conditions, and the metabolic activity of the starter culture. In the study, morphological, biochemical, and molecular characteristics were employed to identify the bacteria obtained from homemade yogurts produced in different regions of Turkey. A collection of 91 Strep. thermophilus and 35 L. bulgaricus strains were investigated for their lactic acid- and acetaldehyde-formation capabilities in various media such as cow milk, LM17 agar, and aerobic-anaerobic SM17 agar or de Man, Rogosa, and Sharpe agar. The amounts of the metabolites generated by each strain in all conditions were quantified by HPLC. The levels were found to vary depending on the species, the strain, and the growth conditions used. Whereas lactic acid production ranged between 0 and 77.9 mg/kg for Strep. thermophilus strains, it ranged from 0 to 103.5 mg/kg for L. bulgaricus. Correspondingly, the ability to generate acetaldehyde ranged from 0 to 105.9 mg/kg in Strep. thermophilus and from 0 to 126.9 mg/kg in L. bulgaricus. Our study constitutes the first attempt to determine characteristics of the wild strains isolated from traditional Turkish yogurts, and the approach presented here, which reveals the differences in metabolite production abilities of the

Arabidopsis thaliana defense response to the ochratoxin A-producing strain (Aspergillus ochraceus 3.4412).

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Hao, Junran; Wu, Weihong; Wang, Yan; Yang, Zhuojun; Liu, Yang; Lv, Yangjun; Zhai, Yanan; Yang, Jing; Liang, Zhihong; Huang, Kunlun; Xu, Wentao

2015-05-01

OTA-producing strain Aspergillus ochraceus induced necrotic lesions, ROS accumulation and defense responses in Arabidopsis . Primary metabolic and defense-related proteins changed in proteomics. Ascorbate-glutathione cycle and voltage-dependent anion-selective channel proteins fluctuated. Mycotoxigenic fungi, as widespread contaminants by synthesizing mycotoxins in pre-/post-harvest infected plants and even stored commercial cereals, could usually induce plant-fungi defense responses. Notably, ochratoxin A (OTA) is a nephrotoxic, hepatotoxic, teratogenic, immunotoxic and phytotoxic mycotoxin. Herein, defense responses of model system Arabidopsis thaliana detached leaves to infection of Aspergillus ochraceus 3.4412, an OTA high-producing strain, were studied from physiological, proteomic and transcriptional perspectives. During the first 72 h after inoculation (hai), the newly formed hypersensitive responses-like lesions, decreased chlorophyll content, accumulated reactive oxygen species and upregulated defense genes expressions indicated the defense response was induced in the leaves with the possible earlier motivated jasmonic acid/ethylene signaling pathways and the later salicylic acid-related pathway. Moreover, proteomics using two-dimensional gel electrophoresis 72 hai showed 16 spots with significantly changed abundance and 13 spots corresponding to 12 unique proteins were successfully identified by MALDI-TOF/TOF MS/MS. Of these, six proteins were involved in basic metabolism and four in defense-related processes, which included glutathione-S-transferase F7, voltage-dependent anion-selective channel protein 3 (VDAC-3), osmotin-like protein OSM34 and blue copper-binding protein. Verified from proteomic and/or transcriptional perspectives, it is concluded that the primary metabolic pathways were suppressed with the ascorbate-glutathione cycle fluctuated in response to A. ochraceus and the modulation of VDACs suggested the possibility of structural damage and

Comparative genomics of citric-acid-producing Aspergillus niger ATCC 1015 versus enzyme-producing CBS 513.88

DEFF Research Database (Denmark)

Andersen, Mikael Rørdam; Salazar, Margarita Pena; Schaap, Peter J.

2011-01-01

The filamentous fungus Aspergillus niger exhibits great diversity in its phenotype. It is found globally, both as marine and terrestrial strains, produces both organic acids and hydrolytic enzymes in high amounts, and some isolates exhibit pathogenicity. Although the genome of an industrial enzyme......-producing A. niger strain (CBS 513.88) has already been sequenced, the versatility and diversity of this species compel additional exploration. We therefore undertook whole-genome sequencing of the acidogenic A. niger wild-type strain (ATCC 1015) and produced a genome sequence of very high quality. Only 15...

Draft genome sequences of Escherichia coli O113:H21 strains recovered from a major produce-production region in California

Science.gov (United States)

Shiga toxin-producing Escherichia coli is a foodborne and waterborne pathogen and is responsible for outbreaks of human gastroenteritis. This report documents the draft genome sequences of seven O113:H21 strains recovered from livestock, wildlife, and soil samples collected in a major agricultural r...

Fumonisin and Ochratoxin Production in Industrial Aspergillus niger Strains

DEFF Research Database (Denmark)

Frisvad, Jens Christian; Larsen, Thomas Ostenfeld; Thrane, Ulf

2011-01-01

as safe). However, A. niger has the potential to produce two groups of potentially carcinogenic mycotoxins: fumonisins and ochratoxins. In this study all available industrial and many non-industrial strains of A. niger (180 strains) as well as 228 strains from 17 related black Aspergillus species were...... examined for mycotoxin production. None of the related 17 species of black Aspergilli produced fumonisins. Fumonisins (B(2), B(4), and B(6)) were detected in 81% of A. niger, and ochratoxin A in 17%, while 10% of the strains produced both mycotoxins. Among the industrial strains the same ratios were 83......%, 33% and 26% respectively. Some of the most frequently used strains in industry NRRL 337, 3112 and 3122 produced both toxins and several strains used for citric acid production were among the best producers of fumonisins in pure agar culture. Most strains used for other biotechnological processes also...

Detection and characterization of bacteriocin-producing Lactococcus lactis strains Detecção e caracterização de Lactococcus lactis produtores de bacteriocinas

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Izildinha Moreno

1999-04-01

Full Text Available One hundred sixty seven strains of Lactococcus lactis were screened for bacteriocin production by well diffusion assay of GM17 agar. Fourteen (8.4% produced antimicrobial activity other than organic acids, bacteriophages or hydrogen peroxide. The frequency of bacteriocin production ranged from 2% in L. lactis subsp. cremoris up to 12% in L. lactis subsp. lactis. Antimicrobial activities were not observed in any strain of L. lactis subsp. lactis var. diacetylactis. Among thirteen bacteriocin-producing strains and two nisin-producing strains (L. lactis subsp. lactis ATCC 11454 and L. lactis subsp. lactis CNRZ 150, eight (53% were characterized as lactose-positive (Lac+ and proteinase-negative (Prt-. The bacteriocin-producing cultures were also characterized on the basis of plasmid content. All strains had 2 to 7 plasmids with molecular weights varying from 0.5 to 28.1 Mdal. Four strains (ITAL 435, ITAL 436, ITAL 437 and ITAL 438 showed identical profiles and the other were quite distinct.Um total de 167 linhagens de L. lactis foi selecionado para os testes de produção de bacteriocinas pelo método de difusão em poços em agar GM17. Desse total, 14 (8.4% produziram substâncias inibidoras que não foram associadas com ácidos orgânicos, peróxido de hidrogênio e bacteriófagos. A frequência de produção de bacteriocinas variou de 2% em L. lactis subsp. cremoris a 12% em L. lactis subsp. lactis. Nenhuma das linhagens de L. lactis subsp. lactis var. diacetylactis produziu substâncias inibidoras. De 13 linhagens produtoras de bacteriocinas e duas de nisina (L. lactis subsp. lactis ATCC 11454 e L. lactis subsp. lactis CNRZ 150, 8 (53% foram caracterizadas como lactose-positivas (Lac+ e proteinase-negativas (Prt-. As linhagens produtoras de bacteriocinas também foram caracterizadas no seu conteúdo de plasmídios. Elas apresentaram de 2 a 7 plasmídios, com pesos moleculares aproximados de 0.5 a 28.1 Mdal. Quatro linhagens (ITAL 435, ITAL 436

Probiotic Properties of Lactobacillus fermentum Strains Isolated from Human Oral Samples and Description of their Antibacterial Activity.

Science.gov (United States)

Fuochi, Virginia; Volti, Giovanni Li; Furneri, Pio M

2017-01-01

Gram positive bacteria produce peptides, defined bacteriocins which exhibit good antibacterial activity. We evaluated the ability of L. fermentum to produce bacteriocins having therefore, good probiotic features and finally, be safe towards microglial cells. Eight wild strains, identified using molecular techniques, were investigated for the evaluation of resistance to bile salts, low pH, H2O2 production, biofilm formation, antibacterial activity and safety on microglia cells (BV2). The determination of the susceptibility/resistance profile showed that the strains are sensitive to the antibiotics tested. All strains showed a good tolerability to extremely low pH as well as resisting in presence of bile salts. In addition, the strains showed excellent activity against pathogens and one of them (LAC 42) showed activity also against Pseudomonas aeruginosa and Klebsiella pneumoniae. Finally, LAC 42 and its active compound did not change microglia cell viability following 24h exposure. Our data on this antibacterial molecule suggest that it is a compound with low molecular weight and with highly hydrophilic component. These results describe the characteristics of Lactobacillus strains and provide evidences for their possible use as new potential probiotic. In addition, other studies are now warranted to exploit the antibacterial activity of the supernatant LAC 42 and for its complete chemical characterization. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

AI-2 does not function as a quorum sensing molecule in Campylobacter jejuni during exponential growth in vitro

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Winzer Klaus

2009-10-01

Full Text Available Abstract Background Campylobacter jejuni contains a homologue of the luxS gene shown to be responsible for the production of the signalling molecule autoinducer-2 (AI-2 in Vibrio harveyi and Vibrio cholerae. The aim of this study was to determine whether AI-2 acted as a diffusible quorum sensing signal controlling C. jejuni gene expression when it is produced at high levels during mid exponential growth phase. Results AI-2 activity was produced by the parental strain NCTC 11168 when grown in rich Mueller-Hinton broth (MHB as expected, but interestingly was not present in defined Modified Eagles Medium (MEM-α. Consistent with previous studies, the luxS mutant showed comparable growth rates to the parental strain and exhibited decreased motility halos in both MEM-α and MHB. Microarray analysis of genes differentially expressed in wild type and luxS mutant strains showed that many effects on mRNA transcript abundance were dependent on the growth medium and linked to metabolic functions including methionine metabolism. Addition of exogenously produced AI-2 to the wild type and the luxS mutant, growing exponentially in either MHB or MEM-α did not induce any transcriptional changes as analysed by microarray. Conclusion Taken together these results led us to conclude that there is no evidence for the role of AI-2 in cell-to-cell communication in C. jejuni strain NCTC 11168 under the growth conditions used, and that the effects of the luxS mutation on the transcriptome are related to the consequential loss of function in the activated methyl cycle.

AI-2 does not function as a quorum sensing molecule in Campylobacter jejuni during exponential growth in vitro.

Science.gov (United States)

Holmes, Kathryn; Tavender, Tim J; Winzer, Klaus; Wells, Jerry M; Hardie, Kim R

2009-10-08

Campylobacter jejuni contains a homologue of the luxS gene shown to be responsible for the production of the signalling molecule autoinducer-2 (AI-2) in Vibrio harveyi and Vibrio cholerae. The aim of this study was to determine whether AI-2 acted as a diffusible quorum sensing signal controlling C. jejuni gene expression when it is produced at high levels during mid exponential growth phase. AI-2 activity was produced by the parental strain NCTC 11168 when grown in rich Mueller-Hinton broth (MHB) as expected, but interestingly was not present in defined Modified Eagles Medium (MEM-alpha). Consistent with previous studies, the luxS mutant showed comparable growth rates to the parental strain and exhibited decreased motility halos in both MEM-alpha and MHB. Microarray analysis of genes differentially expressed in wild type and luxS mutant strains showed that many effects on mRNA transcript abundance were dependent on the growth medium and linked to metabolic functions including methionine metabolism. Addition of exogenously produced AI-2 to the wild type and the luxS mutant, growing exponentially in either MHB or MEM-alpha did not induce any transcriptional changes as analysed by microarray. Taken together these results led us to conclude that there is no evidence for the role of AI-2 in cell-to-cell communication in C. jejuni strain NCTC 11168 under the growth conditions used, and that the effects of the luxS mutation on the transcriptome are related to the consequential loss of function in the activated methyl cycle.

Genome sequences of three tunicamycin-producing Streptomyces strains; S. chartreusis NRRL 12338, S. chartreusis NRRL 3882, and S. lysosuperificus ATCC 31396

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S. chartreusis strains NRRL 12338 and NRRL 3882, S. clavuligerus NRRL 3585, and S. lysosuperificus ATCC 31396, are known producers of tunicamycins, and also of charteusins, clavulinate, cephalosporins, holomycins, and calcimycin. Here we announce the sequencing of the S. lysosuperificus and the two...

Unusual Δ7,12,19 C35:3 Alkenone Produced by the Mutant Emiliania huxleyi strain CCMP2758 in Culture

Science.gov (United States)

Zheng, Y.; Huang, Y.; Zhang, Y.; Dillon, J. T.

2015-12-01

Alkenones with chain length ranging from C37 to C40 are highly specific biomarkers for certain haptophyte algae in ocean and lake sediments and have been widely used for paleoclimate studies. Short chain alkenones (e.g., C35 and C36) have been found in environmental and culture samples but the origin and structures of these compounds are not fully understood. The benchmark marine alkenone producer, Emiliania huxleyi CCMP2758 strain (the mutant of strain CCMP1742, NEPCC55a) was reported to make 35:2 alkenone when cultured at 15 °C (Prahl et al., 2006). Here we show, when this strain is cultured at lower temperatures (e.g., 4°C), CCMP2758 produces large amount of 35:3 alkenone with unusual double bond positions of Δ7,12,19. We determined the double bond positions of the C35:3 methyl ketonee based on GC-MS analysis of cyclobutylimine derivatives and dimethyl disulfide derivatives respectively, and provide the first temperature calibrations based on the unsaturation ratios of C35 alkenones. Previous studies have found 35:2 alkenone with three methylene interruption in the Black Sea sediment, but it is the first time that an alkenone with a mixed three and five methylene interruption is found. The discovery of short chain alkenones with unusual double bond positions may shed new light to alkenone biosynthesis.

Electron Accumulative Molecules.

Science.gov (United States)

Buades, Ana B; Sanchez Arderiu, Víctor; Olid-Britos, David; Viñas, Clara; Sillanpää, Reijo; Haukka, Matti; Fontrodona, Xavier; Paradinas, Markos; Ocal, Carmen; Teixidor, Francesc

2018-02-28

With the goal to produce molecules with high electron accepting capacity and low reorganization energy upon gaining one or more electrons, a synthesis procedure leading to the formation of a B-N(aromatic) bond in a cluster has been developed. The research was focused on the development of a molecular structure able to accept and release a specific number of electrons without decomposing or change in its structural arrangement. The synthetic procedure consists of a parallel decomposition reaction to generate a reactive electrophile and a synthesis reaction to generate the B-N(aromatic) bond. This procedure has paved the way to produce the metallacarboranylviologen [M(C 2 B 9 H 11 )(C 2 B 9 H 10 )-NC 5 H 4 -C 5 H 4 N-M'(C 2 B 9 H 11 )(C 2 B 9 H 10 )] (M = M' = Co, Fe and M = Co and M' = Fe) and semi(metallacarboranyl)viologen [3,3'-M(8-(NC 5 H 4 -C 5 H 4 N-1,2-C 2 B 9 H 10 )(1',2'-C 2 B 9 H 11 )] (M = Co, Fe) electron cumulative molecules. These molecules are able to accept up to five electrons and to donate one in single electron steps at accessible potentials and in a reversible way. By targeted synthesis and corresponding electrochemical tests each electron transfer (ET) step has been assigned to specific fragments of the molecules. The molecules have been carefully characterized, and the electronic communication between both metal centers (when this situation applies) has been definitely observed through the coplanarity of both pyridine fragments. The structural characteristics of these molecules imply a low reorganization energy that is a necessary requirement for low energy ET processes. This makes them electronically comparable to fullerenes, but on their side, they have a wide range of possible solvents. The ET from one molecule to another has been clearly demonstrated as well as their self-organizing capacity. We consider that these molecules, thanks to their easy synthesis, ET, self-organizing capacity, wide range of solubility, and easy processability, can

Changes in diffusion properties of biological tissues associated with mechanical strain

International Nuclear Information System (INIS)

Tanaka, Kenichiro; Imae, T.; Mima, Kazuo; Sekino, Masaki; Ohsaki, Hiroyuki; Ueno, Shogo

2007-01-01

Mechanical strain in biological tissues causes a change in the diffusion properties of water molecules. This paper proposes a method of estimating mechanical strain in biological tissues using diffusion magnetic resonance imaging (MRI). Measurements were carried out on uncompressed and compressed chicken skeletal muscles. A theoretical model of the diffusion of water molecules in muscle fibers was derived based on Tanner's equation. Diameter of the muscle fibers was estimated by fitting the model equation to the measured signals. Changes in the mean diffusivity (MD), the fractional anisotropy (FA), and diameter of the muscle fiber did not have any statistical significance. The intracellular diffusion coefficient (D int ) was changed by mechanical strain (p<.05). This method has potential applications in the quantitative evaluation of strain in biological tissues, a though it poses several technical challenges. (author)

Screening of physiologically active strain of the filamentous fungi - a producer of a complex of lytic enzymes

International Nuclear Information System (INIS)

Kurbatova, E.I.; Sokolova, E.N.; Borshcheva, Yu.A.; Alsivar, S.K.A.; Rimareva, L.V.

2014-01-01

Filamentous Aspergillus fungi were studied to obtain a producer of a complex of the enzymes specific to biodegradation of polymers of cellular walls of vegetable and microbic biomass. Strains were selected by the increased biosynthetic ability in relation to the beta-glucanase (BG), chitinase (CT), mannanase (MN), proteases and pectinases. It was estimated during deep cultivation in the environment containing wheat bran. The fullest complex of hydrolytic enzymes (glucanase, MN, CT, protease and a polygalacturonase (PG)), and also the level of enzymatic activities was in the culture liquid obtained as a result of biosynthesis of Aspergillus foetidus 37-4 (S 37-4) strain. For its cultivation the medium containing salts like potassium dihydrogen phosphate, magnesium sulfate and ammonium sulfate in optimum concentration, and also dioses (maltose, sucrose) and polysaccharides (starch, chitin, pectin) was chosen. The greatest zones of hydrolysis are traced during planting S 37-4 in agar medium containing maltose and low methoxyl citrus pectin. As the synthesis inductor of hemicellulase, MN and CT malt sprouts were used, and of PG - not clarified beet bin fibers. Cultivation was carried out on a thermostatically controlled shaker at 30 deg. C for 120 h. Increase of activity of synthesizable enzymes when using low methoxyl citrus pectin as a media part equaled for BG 5-19%, for PG - 25%, when using a maltose for CT - 100%, MN - 29%. To increase biosynthetic ability of S 37-4 as a mutagen 3-staged ultra-violet radiation (wavelength is 265 nanometers) was applied. The obtained 379-K-5 strain surpassed in activity level a parental strain BG - by 84.8%, CT - by 45.0%, MN - by 62.9%, PG - by 89.0%. The following (4th) stage of radiation led to death of the strain. In comparison with a parental S 37-4 the colony of a mutant strain possessed the bigger size and plentiful formation of an air mycelium, ability to sporogenesis was less expressed

A New Strain Collection for Improved Expression of Outer Membrane Proteins

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Ina Meuskens

2017-11-01

Full Text Available Almost all integral membrane proteins found in the outer membranes of Gram-negative bacteria belong to the transmembrane β-barrel family. These proteins are not only important for nutrient uptake and homeostasis, but are also involved in such processes as adhesion, protein secretion, biofilm formation, and virulence. As surface exposed molecules, outer membrane β-barrel proteins are also potential drug and vaccine targets. High production levels of heterologously expressed proteins are desirable for biochemical and especially structural studies, but over-expression and subsequent purification of membrane proteins, including outer membrane proteins, can be challenging. Here, we present a set of deletion mutants derived from E. coli BL21(DE3 designed for the over-expression of recombinant outer membrane proteins. These strains harbor deletions of four genes encoding abundant β-barrel proteins in the outer membrane (OmpA, OmpC, OmpF, and LamB, both single and in all combinations of double, triple, and quadruple knock-outs. The sequences encoding these outer membrane proteins were deleted completely, leaving only a minimal scar sequence, thus preventing the possibility of genetic reversion. Expression tests in the quadruple mutant strain with four test proteins, including a small outer membrane β-barrel protein and variants thereof as well as two virulence-related autotransporters, showed significantly improved expression and better quality of the produced proteins over the parent strain. Differences in growth behavior and aggregation in the presence of high salt were observed, but these phenomena did not negatively influence the expression in the quadruple mutant strain when handled as we recommend. The strains produced in this study can be used for outer membrane protein production and purification, but are also uniquely useful for labeling experiments for biophysical measurements in the native membrane environment.

Regulation of IgE antibody production by serum molecules. II. Strain-specificity of the suppressive activity of serum from complete Freund's adjuvant-immune low responder mouse donors

International Nuclear Information System (INIS)

Katz, D.H.; Tung, A.S.

1978-01-01

IgE antibody production in mice of high and low IgE responder phenotypes, respectively, can be appreciably enhanced in magnitude after low-dose whole-body x irradiation. Such enhanced responses, as well as adoptive secondary IgE responses, can be markedly suppressed by passive transfer of CFA-immune serum in low responder strains, but not in high responder strains. The studies presented here demonstrate that the suppressive activity of CFA-immune serum on IgE antibody production is strain specific. This is true even in reciprocal combinations of low IgE responder SJL and C57BL/6 mice, in which it was shown that serum capable of suppressing mice of the isologous strain was ineffective in diminishing IgE antibody production in the other low responder strain. Absence of suppressive activity in CFA-immune sera obtained from H-2 haplotypes while sharing many similarities in the background genome and, conversely, effective suppressive activity of H-2 congenic donor sera when H-2-identities between donor and recipient mice existed, strongly suggested a role, at least in part, of H-2 genes in dictating the strain specificity of such suppressive activity. Additional experiments provided evidence for a possible role of macrophages in catabolism of the active molecules in CFA-immune sera. These observations, together with those presented in the preceding paper, may provide valuable insight toward successful development of appropriate manipulations that could ultimately convert high IgE responder individuals into low responders

Genomic and Proteomic Characterization of Bacteriocin-Producing Leuconostoc mesenteroides Strains Isolated from Raw Camel Milk in Two Southwest Algerian Arid Zones

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Zineb Benmechernene

2014-01-01

Full Text Available Information on the microbiology of camel milk is very limited. In this work, the genetic characterization and proteomic identification of 13 putative producing bacteriocin Leuconostoc strains exhibiting antilisterial activity and isolated from camel milk were performed. DNA sequencing of the 13 selected strains revealed high homology among the 16S rRNA genes for all strains. In addition, 99% homology with Leuconostoc mesenteroides was observed when these sequences were analysed by the BLAST tool against other sequences from reference strains deposited in the Genbank. Furthermore, the isolates were characterized by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDITOF MS which allowed for the identification of 2 mass peaks 6242 m/z and 5118 m/z that resulted to be specific to the species L. mesenteroides. Remarkably, the phyloproteomic tree provided more intraspecific information of L. mesenteroides than phylogenetic analysis. Accordingly, phyloproteomic analysis grouped L. mesenteroides strains into different subbranches, while all L. mesenteroides isolates were grouped in the same branch according to phylogenetic analysis. This study represents, to our knowledge, the first report on the use of MALDI-TOF MS on the identification of LAB isolated from camel milk.

Genomic and proteomic characterization of bacteriocin-producing Leuconostoc mesenteroides strains isolated from raw camel milk in two southwest Algerian arid zones.

Science.gov (United States)

Benmechernene, Zineb; Fernández-No, Inmaculada; Quintela-Baluja, Marcos; Böhme, Karola; Kihal, Mebrouk; Calo-Mata, Pilar; Barros-Velázquez, Jorge

2014-01-01

Information on the microbiology of camel milk is very limited. In this work, the genetic characterization and proteomic identification of 13 putative producing bacteriocin Leuconostoc strains exhibiting antilisterial activity and isolated from camel milk were performed. DNA sequencing of the 13 selected strains revealed high homology among the 16S rRNA genes for all strains. In addition, 99% homology with Leuconostoc mesenteroides was observed when these sequences were analysed by the BLAST tool against other sequences from reference strains deposited in the Genbank. Furthermore, the isolates were characterized by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDITOF MS) which allowed for the identification of 2 mass peaks 6242 m/z and 5118 m/z that resulted to be specific to the species L. mesenteroides. Remarkably, the phyloproteomic tree provided more intraspecific information of L. mesenteroides than phylogenetic analysis. Accordingly, phyloproteomic analysis grouped L. mesenteroides strains into different subbranches, while all L. mesenteroides isolates were grouped in the same branch according to phylogenetic analysis. This study represents, to our knowledge, the first report on the use of MALDI-TOF MS on the identification of LAB isolated from camel milk.

Anti-bacterial Efficacy of Bacteriocin Produced by Marine Bacillus subtilis Against Clinically Important Extended Spectrum Beta-Lactamase Strains and Methicillin-Resistant Staphylococcus aureus

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Suresh Mickymaray

2018-02-01

Full Text Available Objective: To investigate the anti-bacterial efficacy of bacteriocin produced by Bacillus subtilis SM01 (GenBank accession no: KY612347, a Gram-positive marine bacterium, against Extended Spectrum Beta-Lactamase (ESBL producing Gram-negative pathogens Acinetobacter baumannii, Pseudomonas aeruginosa, and Escherichia coli, and Gram-positive pathogen Methicillin-Resistant Staphylococcus aureus (MRSA. Methods: A marine bacterium was isolated from mangrove sediment from the Red Sea coast of Jeddah, Kingdom of Saudi Arabia, and identified based on its morphological, biochemical, and molecular characteristics. The bacteriocin production using this isolate was carried out in brain heart infusion broth (BHIB medium. The Anti-bacterial activity of bacteriocin was evaluated against selected ESBL strains and MRSA by the well agar method. The effects of incubation time, pH, and temperature on the Anti-bacterial activity were studied. Results: The bacteriocin Bac-SM01 produced by B. subtilis SM01 demonstrated broad-spectrum Anti-bacterial activity against both Gram-negative and -positive bacteria. The present study is the first report that the bacteriocin Bac-SM01 inhibits the growth of ESBL producing Gram-negative strains A. baumannii, P. aeruginosa, and E. coli, and a Gram-positive MRSA strain. The optimum incubation time, pH, and temperature for the Anti-bacterial activity of Bac-SM01 was 24 h, 7, and 37°C respectively. Conclusion: The overall investigation can conclude that the bacteriocin Bac-SM01 from the marine isolate Bacillus subtilis SM01 could be used as an alternative Anti-bacterial agent in pharmaceutical products.

Fumonisin and Ochratoxin Production in Industrial Aspergillus niger Strains

Science.gov (United States)

Frisvad, Jens C.; Larsen, Thomas O.; Thrane, Ulf; Meijer, Martin; Varga, Janos; Samson, Robert A.; Nielsen, Kristian F.

2011-01-01

Aspergillus niger is perhaps the most important fungus used in biotechnology, and is also one of the most commonly encountered fungi contaminating foods and feedstuffs, and occurring in soil and indoor environments. Many of its industrial applications have been given GRAS status (generally regarded as safe). However, A. niger has the potential to produce two groups of potentially carcinogenic mycotoxins: fumonisins and ochratoxins. In this study all available industrial and many non-industrial strains of A. niger (180 strains) as well as 228 strains from 17 related black Aspergillus species were examined for mycotoxin production. None of the related 17 species of black Aspergilli produced fumonisins. Fumonisins (B2, B4, and B6) were detected in 81% of A. niger, and ochratoxin A in 17%, while 10% of the strains produced both mycotoxins. Among the industrial strains the same ratios were 83%, 33% and 26% respectively. Some of the most frequently used strains in industry NRRL 337, 3112 and 3122 produced both toxins and several strains used for citric acid production were among the best producers of fumonisins in pure agar culture. Most strains used for other biotechnological processes also produced fumonisins. Strains optimized through random mutagenesis usually maintained their mycotoxin production capability. Toxigenic strains were also able to produce the toxins on media suggested for citric acid production with most of the toxins found in the biomass, thereby questioning the use of the remaining biomass as animal feed. In conclusion it is recommended to use strains of A. niger with inactive or inactivated gene clusters for fumonisins and ochratoxins, or to choose isolates for biotechnological uses in related non-toxigenic species such as A. tubingensis, A. brasiliensis, A vadensis or A. acidus, which neither produce fumonisins nor ochratoxins. PMID:21853139

Growth and Survival of Acid-Resistant and Non-Acid-Resistant Shiga-Toxin-Producing Escherichia coli Strains during the Manufacture and Ripening of Camembert Cheese.

Science.gov (United States)

Montet, M P; Jamet, E; Ganet, S; Dizin, M; Miszczycha, S; Dunière, L; Thevenot, D; Vernozy-Rozand, C

2009-01-01

Growth and survival of acid-resistant (AR) and non-acid-resistant (NAR) Shiga-toxin-producing Escherichia coli (STEC) strains were investigated during the manufacture and ripening of microfiltered milk Camembert cheeses. The induction of acid resistance of the STEC strains in cheeses was also studied. Six different mixtures of AR and/or NAR STEC strains were inoculated separately into microfiltered milk at a level of 10(3) CFU mL(-1). The STEC counts (AR and NAR) initially increased by 1 to 2 log(10) CFU g(-1) during cheese-making. Thereafter, the populations stabilized during salting/drying and then decreased during the early stages of ripening. Exposing the STEC strains in artificially inoculated cheeses to simulated gastric fluid (SGF - pH: 2.0) reduced the number of NAR strains to undetectable levels within 40 minutes, versus 120 minutes for the AR STEC strains. AR and NAR STEC were able to survive during the manufacture and ripening of Camembert cheese prepared from microfiltered milk with no evidence of induced acid tolerance in NAR STEC strains.

Growth and Survival of Acid-Resistant and Non-Acid-Resistant Shiga-Toxin-Producing Escherichia coli Strains during the Manufacture and Ripening of Camembert Cheese

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M. P. Montet

2009-01-01

Full Text Available Growth and survival of acid-resistant (AR and non-acid-resistant (NAR Shiga-toxin-producing Escherichia coli (STEC strains were investigated during the manufacture and ripening of microfiltered milk Camembert cheeses. The induction of acid resistance of the STEC strains in cheeses was also studied. Six different mixtures of AR and/or NAR STEC strains were inoculated separately into microfiltered milk at a level of 103 CFU mL−1. The STEC counts (AR and NAR initially increased by 1 to 2 log⁡10 CFU g−1 during cheese-making. Thereafter, the populations stabilized during salting/drying and then decreased during the early stages of ripening. Exposing the STEC strains in artificially inoculated cheeses to simulated gastric fluid (SGF - pH: 2.0 reduced the number of NAR strains to undetectable levels within 40 minutes, versus 120 minutes for the AR STEC strains. AR and NAR STEC were able to survive during the manufacture and ripening of Camembert cheese prepared from microfiltered milk with no evidence of induced acid tolerance in NAR STEC strains.

Targeted Gene Disruption of the Cyclo (L-Phe, L-Pro Biosynthetic Pathway in Streptomyces sp. US24 Strain

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Samiha Sioud

2007-01-01

Full Text Available We have previously isolated a new actinomycete strain from Tunisian soil called Streptomyces sp. US24, and have shown that it produces two bioactive molecules including a Cyclo (L-Phe, L-Pro diketopiperazine (DKP. To identify the structural genes responsible for the synthesis of this DKP derivative, a PCR amplification (696 bp was carried out using the Streptomyces sp. US24 genomic DNA as template and two degenerate oligonucleotides designed by analogy with genes encoding peptide synthetases (NRPS. The detection of DKP derivative biosynthetic pathway of the Streptomyces sp. US24 strain was then achieved by gene disruption via homologous recombination using a suicide vector derived from the conjugative plasmid pSET152 and containing the PCR product. Chromatography analysis, biological tests and spectroscopic studies of supernatant cultures of the wild-type Streptomyces sp. US24 strain and three mutants obtained by this gene targeting disruption approach showed that the amplified DNA fragment is required for Cyclo (L-Phe, L-Pro biosynthesis in Streptomyces sp. US24 strain. This DKP derivative seems to be produced either directly via a nonribosomal pathway or as a side product in the course of nonribosomal synthesis of a longer peptide.

Cloning and Characterization of a Unique Cytotoxic Protein Parasporin-5 Produced by Bacillus thuringiensis A1100 Strain

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Keisuke Ekino

2014-06-01

Full Text Available Parasporin is the cytocidal protein present in the parasporal inclusion of the non-insecticidal Bacillus thuringiensis strains, which has no hemolytic activity but has cytocidal activities, preferentially killing cancer cells. In this study, we characterized a cytocidal protein that belongs to this category, which was designated parasporin-5 (PS5. PS5 was purified from B. thuringiensis serovar tohokuensis strain A1100 based on its cytocidal activity against human leukemic T cells (MOLT-4. The 50% effective concentration (EC50 of PS5 to MOLT-4 cells was approximately 0.075 μg/mL. PS5 was expressed as a 33.8-kDa inactive precursor protein and exhibited cytocidal activity only when degraded by protease at the C-terminal into smaller molecules of 29.8 kDa. Although PS5 showed no significant homology with other known parasporins, a Position Specific Iterative-Basic Local Alignment Search Tool (PSI-BLAST search revealed that the protein showed slight homology to, not only some B. thuringiensis Cry toxins, but also to aerolysin-type β-pore-forming toxins (β-PFTs. The recombinant PS5 protein could be obtained as an active protein only when it was expressed in a precursor followed by processing with proteinase K. The cytotoxic activities of the protein against various mammalian cell lines were evaluated. PS5 showed strong cytocidal activity to seven of 18 mammalian cell lines tested, and low to no cytotoxicity to the others.

Protection of a PWR nuclear power stations against corrosion using hydrogen molecules to capture oxygen molecules

International Nuclear Information System (INIS)

Nahili, M.

2004-01-01

A protection method for the primary loops metals of nuclear power plants from corrosion was investigated. Hydrogen molecules were added to the primary circuit to eliminate oxygen molecules produced by radiolysis of coolant at the reactor core. The hydrogen molecules were produced by electrolyses of water and then added when the coolant water was passing through the primary coolant circuit. Thermodynamical process and the protection methods from corrosion were discussed, the discussion emphasized on the removal of oxygen molecules as one of the protection methods, and compared with other methods. The amount of hydrogen molecules needed for complete removal of oxygen was estimated in two cases: in the case without passing the water through the oxygen removal system, and in the case of passing water through the system. A pressurized water reactor VVER was chosen to be investigated in this study. The amount of hydrogen molecules was estimated so as to eliminate completely the oxygen molecules from coolant water. The estimated value was found to be less than the permissible range for coolant water for such type of reactors. A simulation study for interaction mechanism between hydrogen and oxygen molecules as water flowing in a tube similar to that of coolant water was performed with different water flow velocities. The interaction between the molecules of hydrogen and oxygen was described. The gas diffusion at the surface of the tube was found to play a major role in the interaction. A mathematical model was found to give full description of the change of oxygen concentration through the tube, as well as, to calculate the length of the tube where the concentration of oxygen reduced to few order of magnitude. (Author)

Removal Capacities of Polycyclic Aromatic Hydrocarbons (PAHs by a Newly Isolated Strain from Oilfield Produced Water

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Yi-Bin Qi

2017-02-01

Full Text Available The polycyclic aromatic hydrocarbon (PAH-degrading strain Q8 was isolated from oilfield produced water. According to the analysis of a biochemical test, 16S rRNA gene, house-keeping genes and DNA–DNA hybridization, strain Q8 was assigned to a novel species of the genus Gordonia. The strain could not only grow in mineral salt medium (MM and utilize naphthalene and pyrene as its sole carbon source, but also degraded mixed naphthalene, phenanthrene, anthracene and pyrene. The degradation ratio of these four PAHs reached 100%, 95.4%, 73.8% and 53.4% respectively after being degraded by Q8 for seven days. A comparative experiment found that the PAHs degradation efficiency of Q8 is higher than that of Gordonia alkaliphila and Gordonia paraffinivorans, which have the capacities to remove PAHs. Fourier transform infrared spectra, saturate, aromatic, resin and asphaltene (SARA and gas chromatography–mass spectrometry (GC–MS analysis of crude oil degraded by Q8 were also studied. The results showed that Q8 could utilize n-alkanes and PAHs in crude oil. The relative proportions of the naphthalene series, phenanthrene series, thiophene series, fluorene series, chrysene series, C21-triaromatic steroid, pyrene, and benz(apyrene were reduced after being degraded by Q8. Gordonia sp. nov. Q8 had the capacity to remediate water and soil environments contaminated by PAHs or crude oil, and provided a feasible way for the bioremediation of PAHs and oil pollution.

[Isolation of an excellent bio-flocculant-producing strain and its application in the treatment of cold-rolling waste oily water].

Science.gov (United States)

Lei, Guo-Yuan; Ding, Cui-Ping; Yang, Jia-Xuan

2011-09-01

An excellent strain (designated as T-3) which produces bio-flocculants was isolated from soil samples, and identified as Klebsiella sp. species based on the analysis of morphology, physiology and biochemistry and 16S rDNA sequences measurement. The effects of culture conditions such as pH values, temperature, carbon sources and nitrogen sources on bio-flocculants production by T-3 strain were studied. The experiment results show that T-3 strain has better adaptability to carbon sources and nitrogen sources, and higher capacity of bio-flocculants was obtained when the initial pH value of culture and temperature were 9 and 25 degrees C respectively. Based on the colorimetric reactions of proteins and polysaccharide substance, ultraviolet scanning analysis and Fourier Transform Infrared Spectroscopy analysis, it is found that the bio-flocculants produced by T-3 strain contains -OH and -COO(-) groups and belongs to anionic type flocculant. Moreover, the main component is polysaccharides. The treatment of oily cold-rolling wastewater by the bio-flocculant was investigated and the better result was obtained. When the dosages of CaCl2, bio-flocculants and poly aluminium chloride were 4 g x L(-1), 10% (volume fraction) and 1 g x L(-1) respectively, and the pH value was 7.0, the oil concentration, COD and turbidity were decreased to 10 mg x L(-1), 218.4 mg x L(-1) and 1.36 from 4 819 mg x L(-1), 28 456.8 mg x L(-1) and 3 950 with the removal efficiencies of 99.79%, 92.32% and 99.97% respectively. The interaction between flocculant and oily droplets is achieved by the interaction of Van der Waals force, hydrogen bond and the bridged coordination of Ca2+, in which the bridged coordination of Ca2+ is the dominant.

Capturing of the monoterpene olefin limonene produced in Saccharomyces cerevisiae.

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Jongedijk, Esmer; Cankar, Katarina; Ranzijn, Jorn; van der Krol, Sander; Bouwmeester, Harro; Beekwilder, Jules

2015-01-01

Monoterpene olefins such as limonene are plant compounds with applications as flavouring and fragrance agents, as solvents and potentially also in polymer and fuel chemistry. We engineered baker's yeast Saccharomyces cerevisiae to express a (-)-limonene synthase from Perilla frutescens and a (+)-limonene synthase from Citrus limon. Both proteins were expressed either with their native plastid targeting signal or in a truncated form in which the plastidial sorting signal was removed. The yeast host strain for expression was AE9 K197G, which expresses a mutant Erg20 enzyme. This enzyme catalyses the formation of geranyl diphosphate, which is the precursor for monoterpenes. Several methods were tested to capture limonene produced by the yeast. Extraction from the culture medium by pentane, or by the addition of CaCl2 followed by solid-phase micro-extraction, did not lead to detectable limonene, indicating that limonene is rapidly lost from the culture medium. Volatile terpenes such as limonene may also be trapped in a dodecane phase added to the medium during fermentation. This method resulted in recovery of 0.028 mg/l (+)-limonene and 0.060 mg/l (-)-limonene in strains using the truncated Citrus and Perilla synthases, respectively. Trapping the headspace during culture of the limonene synthase-expressing strains resulted in higher titres, at 0.12 mg/l (+)-limonene and 0.49 mg/l (-)-limonene. These results show that the volatile properties of the olefins produced require specific methods for efficient recovery of these molecules from biotechnological production systems. Copyright © 2014 John Wiley & Sons, Ltd.

Cold guided beams of polar molecules

International Nuclear Information System (INIS)

Motsch, Michael

2010-01-01

This thesis reports on experiments characterizing cold guided beams of polar molecules which are produced by electrostatic velocity filtering. This filtering method exploits the interaction between the polar molecules and the electric field provided by an electrostatic quadrupole guide to extract efficiently the slow molecules from a thermal reservoir. For molecules with large and linear Stark shifts such as deuterated ammonia (ND 3 ) or formaldehyde (H 2 CO), fluxes of guided molecules of 10 10 -10 11 molecules/s are produced. The velocities of the molecules in these beams are in the range of 10-200 m/s and correspond to typical translational temperatures of a few Kelvin. The maximum velocity of the guided molecules depends on the Stark shift, the molecular mass, the geometry of the guide, and the applied electrode voltage. Although the source is operated in the near-effusive regime, the number density of the slowest molecules is sensitive to collisions. A theoretical model, taking into account this velocity-dependent collisional loss of molecules in the vicinity of the nozzle, reproduces the density of the guided molecules over a wide pressure range. A careful adjustment of pressure allows an increase in the total number of molecules, whilst yet minimizing losses due to collisions of the sought-for slow molecules. This is an important issue for future applications. Electrostatic velocity filtering is suited for different molecular species. This is demonstrated by producing cold guided beams of the water isotopologs H 2 O, D 2 O, and HDO. Although these are chemically similar, they show linear and quadratic Stark shifts, respectively, when exposed to external electric fields. As a result, the flux of HDO is larger by one order of magnitude, and the flux of the individual isotopologs shows a characteristic dependence on the guiding electric field. The internal-state distribution of guided molecules is studied with a newly developed diagnostic method: depletion

Indole, a Signaling Molecule Produced by the Gut Microbiota, Negatively Impacts Emotional Behaviors in Rats

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Mathilde Jaglin

2018-04-01

Full Text Available Gut microbiota produces a wide and diverse array of metabolites that are an integral part of the host metabolome. The emergence of the gut microbiome-brain axis concept has prompted investigations on the role of gut microbiota dysbioses in the pathophysiology of brain diseases. Specifically, the search for microbe-related metabolomic signatures in human patients and animal models of psychiatric disorders has pointed out the importance of the microbial metabolism of aromatic amino acids. Here, we investigated the effect of indole on brain and behavior in rats. Indole is produced by gut microbiota from tryptophan, through the tryptophanase enzyme encoded by the tnaA gene. First, we mimicked an acute and high overproduction of indole by injecting this compound in the cecum of conventional rats. This treatment led to a dramatic decrease of motor activity. The neurodepressant oxidized derivatives of indole, oxindole and isatin, accumulated in the brain. In addition, increase in eye blinking frequency and in c-Fos protein expression in the dorsal vagal complex denoted a vagus nerve activation. Second, we mimicked a chronic and moderate overproduction of indole by colonizing germ-free rats with the indole-producing bacterial species Escherichia coli. We compared emotional behaviors of these rats with those of germ-free rats colonized with a genetically-engineered counterpart strain unable to produce indole. Rats overproducing indole displayed higher helplessness in the tail suspension test, and enhanced anxiety-like behavior in the novelty, elevated plus maze and open-field tests. Vagus nerve activation was suggested by an increase in eye blinking frequency. However, unlike the conventional rats dosed with a high amount of indole, the motor activity was not altered and neither oxindole nor isatin could be detected in the brain. Further studies are required for a comprehensive understanding of the mechanisms supporting indole effects on emotional

Indole, a Signaling Molecule Produced by the Gut Microbiota, Negatively Impacts Emotional Behaviors in Rats

Science.gov (United States)

Jaglin, Mathilde; Rhimi, Moez; Philippe, Catherine; Pons, Nicolas; Bruneau, Aurélia; Goustard, Bénédicte; Daugé, Valérie; Maguin, Emmanuelle; Naudon, Laurent; Rabot, Sylvie

2018-01-01

Gut microbiota produces a wide and diverse array of metabolites that are an integral part of the host metabolome. The emergence of the gut microbiome-brain axis concept has prompted investigations on the role of gut microbiota dysbioses in the pathophysiology of brain diseases. Specifically, the search for microbe-related metabolomic signatures in human patients and animal models of psychiatric disorders has pointed out the importance of the microbial metabolism of aromatic amino acids. Here, we investigated the effect of indole on brain and behavior in rats. Indole is produced by gut microbiota from tryptophan, through the tryptophanase enzyme encoded by the tnaA gene. First, we mimicked an acute and high overproduction of indole by injecting this compound in the cecum of conventional rats. This treatment led to a dramatic decrease of motor activity. The neurodepressant oxidized derivatives of indole, oxindole and isatin, accumulated in the brain. In addition, increase in eye blinking frequency and in c-Fos protein expression in the dorsal vagal complex denoted a vagus nerve activation. Second, we mimicked a chronic and moderate overproduction of indole by colonizing germ-free rats with the indole-producing bacterial species Escherichia coli. We compared emotional behaviors of these rats with those of germ-free rats colonized with a genetically-engineered counterpart strain unable to produce indole. Rats overproducing indole displayed higher helplessness in the tail suspension test, and enhanced anxiety-like behavior in the novelty, elevated plus maze and open-field tests. Vagus nerve activation was suggested by an increase in eye blinking frequency. However, unlike the conventional rats dosed with a high amount of indole, the motor activity was not altered and neither oxindole nor isatin could be detected in the brain. Further studies are required for a comprehensive understanding of the mechanisms supporting indole effects on emotional behaviors. As our findings

Effect of ropy and capsular exopolysaccharides producing strain of ...

African Journals Online (AJOL)

The contribution of selected ropy and capsular Lactobacillus plantarum 162RM on texture of fermented milk as well as on the functionality of kareish cheese was established in this study. The cell suspension of this strain was used in combination with commercial starter cultures MY900 (Lactobacillus delbrueckii ssp.

Bacteriocin-like inhibitory activities of seven Lactobacillus delbrueckii subsp. bulgaricus strains against antibiotic susceptible and resistant Helicobacter pylori strains.

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Boyanova, L; Gergova, G; Markovska, R; Yordanov, D; Mitov, I

2017-12-01

The aim of the study was to detect anti-Helicobacter pylori activity of seven Lactobacillus delbrueckii subsp. bulgaricus (GLB) strains by four cell-free supernatant (CFS) types. Activity of non-neutralized and non-heat-treated (CFSs1), non-neutralized and heat-treated (CFSs2), pH neutralized, catalase-treated and non-heat-treated (CFSs3), or neutralized, catalase- and heat-treated (CFSs4) CFSs against 18 H. pylori strains (11 of which with antibiotic resistance) was evaluated. All GLB strains produced bacteriocin-like inhibitory substances (BLISs), the neutralized CFSs of two GLB strains inhibited >81% of test strains and those of four GLB strains were active against >71% of antibiotic resistant strains. Two H. pylori strains were BLIS resistant. The heating did not reduce the CFS activity. Briefly, all GLB strains evaluated produced heat-stable BLISs, although GLB and H. pylori strain susceptibility patterns exhibited differences. Bacteriocin-like inhibitory substance activity can be an advantage for the probiotic choice for H. pylori infection control. In this study, anti-Helicobacter pylori activity of seven Lactobacillus delbrueckii subsp. bulgaricus (GLB) strains was evaluated by four cell-free supernatant (CFS) types. The GLB strains produced heat-stable bacteriocin-like inhibitory substances (BLISs) with a strong anti-H. pylori activity and some neutralized, catalase- and heat-treated CFSs inhibited >83% of the test strains. Bacteriocin-like inhibitory substance production of GLB strains can render them valuable probiotics in the control of H. pylori infection. © 2017 The Society for Applied Microbiology.

Self-organized lattice of ordered quantum dot molecules

International Nuclear Information System (INIS)

Lippen, T. von; Noetzel, R.; Hamhuis, G.J.; Wolter, J.H.

2004-01-01

Ordered groups of InAs quantum dots (QDs), lateral QD molecules, are created by self-organized anisotropic strain engineering of a (In,Ga)As/GaAs superlattice (SL) template on GaAs (311)B in molecular-beam epitaxy. During stacking, the SL template self-organizes into a two-dimensionally ordered strain modulated network on a mesoscopic length scale. InAs QDs preferentially grow on top of the nodes of the network due to local strain recognition. The QDs form a lattice of separated groups of closely spaced ordered QDs whose number can be controlled by the GaAs separation layer thickness on top of the SL template. The QD groups exhibit excellent optical properties up to room temperature

A cost-effective approach to produce 15N-labelled amino acids employing Chlamydomonas reinhardtii CC503.

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Nicolás Carcelén, Jesús; Marchante-Gayón, Juan Manuel; González, Pablo Rodríguez; Valledor, Luis; Cañal, María Jesús; Alonso, José Ignacio García

2017-08-18

The use of enriched stable isotopes is of outstanding importance in chemical metrology as it allows the application of isotope dilution mass spectrometry (IDMS). Primary methods based on IDMS ensure the quality of the analytical measurements and traceability of the results to the international system of units. However, the synthesis of isotopically labelled molecules from enriched stable isotopes is an expensive and a difficult task. Either chemical and biochemical methods to produce labelled molecules have been proposed, but so far, few cost-effective methods have been described. The aim of this study was to use the microalgae Chlamydomonas reinhardtii to produce, at laboratory scale, 15 N-labelled amino acids with a high isotopic enrichment. To do that, a culture media containing 15 NH 4 Cl was used. No kinetic isotope effect (KIE) was observed. The labelled proteins biosynthesized by the microorganism were extracted from the biomass and the 15 N-labelled amino acids were obtained after a protein hydrolysis with HCl. The use of the wall deficient strain CC503 cw92 mt+ is fit for purpose, as it only assimilates ammonia as nitrogen source, avoiding isotope contamination with nitrogen from the atmosphere or the reagents used in the culture medium, and enhancing the protein extraction efficiency compared to cell-walled wild type Chlamydomonas. The isotopic enrichment of the labelled amino acids was calculated from their isotopic composition measured by gas chromatography mass spectrometry (GC-MS). The average isotopic enrichment for the 16 amino acids characterized was 99.56 ± 0.05% and the concentration of the amino acids in the hydrolysate ranged from 18 to 90 µg/mL. Previously reported biochemical methods to produce isotopically labelled proteins have been applied in the fields of proteomics and fluxomics. For these approaches, low amounts of products are required and the isotopic enrichment of the molecules has never been properly determined. So far, only 13

Strain improvement in Streptomyces galilaeus, a producer of anthracycline antibiotics galirubins

International Nuclear Information System (INIS)

Kralovcova, E.; Blumauerova, M.; Vanek, Z.

1977-01-01

The production of epsilon-pyrromycinone glycosides in Streptomyces galilaeus increased 12-fold, with respect to the wild strain, as a result of a sequential procedure including both natural selection and treatment with mutagens (nitrous acid, UV light and γ irradiation). Nitrous acid exhibited the highest mutagenic effect, both in increasing the productivity and in inducing blocked mutants. A mutant strain blocked in the biosynthesis of glycosides and accumulating free epsilon-pyrromycinone as the principal metabolite was obtained. (author)

Effects of UV-B radiation on microcystin production of a toxic strain of Microcystis aeruginosa and its competitiveness against a non-toxic strain

International Nuclear Information System (INIS)

Yang, Zhen; Kong, Fanxiang; Shi, Xiaoli; Yu, Yang; Zhang, Min

2015-01-01

Highlights: • UV-B radiation showed higher inhibition to non-toxin producing than toxin-producing strains on growth and photosynthetic activity. • Both intracellular and extracellular MC contents decreased markedly under UV-B radiation. • Higher resistance to UV-B radiation helped toxin-producing M. aeruginosa to predominate in the competition. - Abstract: Microcystins (MCs) produced by toxic cyanobacteria pose a health hazard to humans and animals. Some environmental factors can alter the MC concentrations by affecting the abundance of toxin-producing strains in a cyanobacteria population and/or their toxin production. In this study, we designed a monoculture and competition experiment to investigate the impacts of UV-B radiation on MC production and the competition between toxin and non-toxin producing strains of Microcystis aeruginosa. UV-B radiation resulted in higher inhibition of the growth and photosynthetic activity of the non-toxin producing strain relative to that observed for the toxin-producing strain. Both intracellular and extracellular MC contents decreased markedly when the toxin-producing strain was exposed to UV-B radiation. In addition, a quantitative real-time PCR assay revealed that the ratio of toxin-producing M. aeruginosa under UV-B exposure was higher than that under PAR alone at an early stage of the experiment. However, its abundance under UV-B exposure was lower compared with the PAR alone treatment after day 12. Our study demonstrated that UV-B radiation has a great impact on the abundance of the toxin-producing strain in the Microcystis population and their toxin production, which suggests that the fluctuation of UV-B radiation affects the MC level of cyanobacteria blooms

Effects of UV-B radiation on microcystin production of a toxic strain of Microcystis aeruginosa and its competitiveness against a non-toxic strain

Energy Technology Data Exchange (ETDEWEB)

Yang, Zhen, E-mail: zhyang@niglas.ac.cn; Kong, Fanxiang, E-mail: fxkong@niglas.ac.cn; Shi, Xiaoli; Yu, Yang; Zhang, Min

2015-02-11

Highlights: • UV-B radiation showed higher inhibition to non-toxin producing than toxin-producing strains on growth and photosynthetic activity. • Both intracellular and extracellular MC contents decreased markedly under UV-B radiation. • Higher resistance to UV-B radiation helped toxin-producing M. aeruginosa to predominate in the competition. - Abstract: Microcystins (MCs) produced by toxic cyanobacteria pose a health hazard to humans and animals. Some environmental factors can alter the MC concentrations by affecting the abundance of toxin-producing strains in a cyanobacteria population and/or their toxin production. In this study, we designed a monoculture and competition experiment to investigate the impacts of UV-B radiation on MC production and the competition between toxin and non-toxin producing strains of Microcystis aeruginosa. UV-B radiation resulted in higher inhibition of the growth and photosynthetic activity of the non-toxin producing strain relative to that observed for the toxin-producing strain. Both intracellular and extracellular MC contents decreased markedly when the toxin-producing strain was exposed to UV-B radiation. In addition, a quantitative real-time PCR assay revealed that the ratio of toxin-producing M. aeruginosa under UV-B exposure was higher than that under PAR alone at an early stage of the experiment. However, its abundance under UV-B exposure was lower compared with the PAR alone treatment after day 12. Our study demonstrated that UV-B radiation has a great impact on the abundance of the toxin-producing strain in the Microcystis population and their toxin production, which suggests that the fluctuation of UV-B radiation affects the MC level of cyanobacteria blooms.

Molecular characterisation of human Shiga toxin-producing Escherichia coli O26 strains: results of an outbreak investigation, Romania, February to August 2016.

Science.gov (United States)

Usein, Codruţa-Romaniţa; Ciontea, Adriana Simona; Militaru, Cornelia Mãdãlina; Condei, Maria; Dinu, Sorin; Oprea, Mihaela; Cristea, Daniela; Michelacci, Valeria; Scavia, Gaia; Zota, Lavinia Cipriana; Zaharia, Alina; Morabito, Stefano

2017-11-01

IntroductionAt the beginning of 2016, an increase in paediatric haemolytic uremic syndrome (HUS) cases was observed in Romania. The microbiological investigations allowed isolation of Shiga toxin-producing Escherichia coli (STEC) O26 as the causative agent from most cases. Methods: An enhanced national surveillance of HUS and severe diarrhoea was established across the country following the identification of the first cases and was carried out until August 2016. A total of 15 strains were isolated from 10 HUS and five diarrhoea cases. Strains were characterised by virulence markers (i.e. stx type/subtype, eae , ehxA genes), phylogroup, genetic relatedness and clonality using PCR-based assays, PFGE and multilocus sequence typing (MLST). The first six strains were further characterised by whole genome sequencing (WGS). Results: Five PCR-defined genotypes were distinguished. All strains from HUS cases harboured stx2a and eae , with or without stx1a , while strains from diarrhoea cases carried exclusively stx1a and eae genes. PFGE resolved strains into multiple pulsotypes, compatible with a certain geographic segregation of the cases, and strains were assigned to phylogroup B1 and sequence type (ST) 21. WGS confirmed the results of conventional molecular methods, brought evidence of O26:H11 serotype, and complemented the virulence profiles. Discussion/conclusion: This first description of STEC O26 strains from cases in Romania showed that the isolates belonged to a diverse population. The virulence content of most strains highlighted a high risk for severe outcome in infected patients. Improving the national surveillance strategy for STEC infections in Romania needs to be further considered.

No evidence of the Shiga toxin-producing E. coli O104:H4 outbreak strain or enteroaggregative E. coli (EAEC found in cattle faeces in northern Germany, the hotspot of the 2011 HUS outbreak area

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Wieler Lothar H

2011-11-01

Full Text Available Abstract Background Ruminants, in particular bovines, are the primary reservoir of Shiga toxin-producing E. coli (STEC, but whole genome analyses of the current German ESBL-producing O104:H4 outbreak strain of sequence type (ST 678 showed this strain to be highly similar to enteroaggregative E. coli (EAEC. Strains of the EAEC pathotype are basically adapted to the human host. To clarify whether in contrast to this paradigm, the O104:H4 outbreak strain and/or EAEC may also be able to colonize ruminants, we screened a total of 2.000 colonies from faecal samples of 100 cattle from 34 different farms - all located in the HUS outbreak region of Northern Germany - for genes associated with the O104:H4 HUS outbreak strain (stx2, terD, rfbO104, fliCH4, STEC (stx1, stx2, escV, EAEC (pAA, aggR, astA, and ESBL-production (blaCTX-M, blaTEM, blaSHV. Results The faecal samples contained neither the HUS outbreak strain nor any EAEC. As the current outbreak strain belongs to ST678 and displays an en-teroaggregative and ESBL-producing phenotype, we additionally screened selected strains for ST678 as well as the aggregative adhesion pattern in HEp-2 cells. However, we were unable to find any strains belonging to ST678 or showing an aggregative adhesion pattern. A high percentage of animals (28% shed STEC, corroborating previous knowl-edge and thereby proving the validity of our study. One of the STEC also harboured the LEE pathogenicity island. In addition, eleven animals shed ESBL-producing E. coli. Conclusions While we are aware of the limitations of our survey, our data support the theory, that, in contrast to other Shiga-toxin producing E. coli, cattle are not the reservoir for the O104:H4 outbreak strain or other EAEC, but that the outbreak strain seems to be adapted to humans or might have yet another reservoir, raising new questions about the epidemiology of STEC O104:H4.

Antiviral activity of the exopolysaccharide produced by Serratia sp. strain Gsm01 against Cucumber mosaic virus.

Science.gov (United States)

Ipper, Nagesh S; Cho, Saeyoull; Lee, Seon Hwa; Cho, Jun Mo; Hur, Jang Hyun; Lim, Chun Keun

2008-01-01

The potential of the exopolysaccharide (EPS) from a Serratia sp. strain Gsm01 as an antiviral agent against a yellow strain of Cucumber mosaic virus (CMV-Y) was evaluated in tobacco plants (Nicotiana tabacum cv. Xanthi-nc). The spray treatment of plants using an EPS preparation, 72 before CMV-Y inoculation, protected them against symptom appearance. Fifteen days after challenge inoculation with CMVY, 33.33% of plants showed mosaic symptoms in EPS-treated plants compared with 100% in the control plants. The EPS-treated plants, which showed mosaic symptoms, appeared three days later than the controls. The enzyme-linked immunosorbent assay (ELISA) and reverse transcriptase polymerase chain reaction (RT-PCR) analyses of the leaves of the protected plants revealed that the EPS treatment affected virus accumulation in those plants. Analysis of phenylalanine ammonia lyase, peroxidase, and phenols in protected plants revealed enhanced accumulation of these substances. The pathogenesis-related (PR) genes expression represented by PR-1b was increased in EPS-treated plants. This is the first report of a systemic induction of protection triggered by EPS produced by Serratia sp. against CMV-Y.

Isolation and characterization of new facultative alkaliphilic Bacillus flexus strains from maize processing waste water (nejayote).

Science.gov (United States)

Sanchez-Gonzalez, M; Blanco-Gamez, A; Escalante, A; Valladares, A G; Olvera, C; Parra, R

2011-04-01

This work describes the isolation and characterization of two new alkaliphilic micro-organisms present in nejayote. Samples of fresh industrial nejayote were plated on nejayote medium and incubated for 4 days at 37 °C. Isolates were identified based on morphological and physiological characteristics, as well as 16S rDNA sequence analysis. Two gram-positive strains, NJY2 and NJY4, able to hydrolyse starch, xylan, and gelatin were isolated from nejayote. Comparative sequence analysis of 16S rDNA and phylogenetic studies indicate that the micro-organisms studied were closely related to members of the Bacillus flexus species. The strains were identified as facultative alkaliphilic salt tolerant bacteria. Isolate NJY2 produced cell associated phenolic acid esterases, able to release ferulic acid from nixtamalised corn bran and ethyl and methyl esters. The isolated strains of B. flexus NJY2 and NJY4 showed important physiological properties to produce high-value molecules from agroindustrial by-products. This is the first report about the isolation of alkaliphilic micro-organisms from nejayote and the first report of phenolic acid esterases synthesised by alkaliphiles. The new alkaliphilic micro-organisms have potential application in the treatment and transformation of tortilla industry residues. © 2011 The Authors. Letters in Applied Microbiology © 2011 The Society for Applied Microbiology.

Light-optimized growth of cyanobacterial cultures: Growth phases and productivity of biomass and secreted molecules in light-limited batch growth.

Science.gov (United States)

Clark, Ryan L; McGinley, Laura L; Purdy, Hugh M; Korosh, Travis C; Reed, Jennifer L; Root, Thatcher W; Pfleger, Brian F

2018-03-27

Cyanobacteria are photosynthetic microorganisms whose metabolism can be modified through genetic engineering for production of a wide variety of molecules directly from CO 2 , light, and nutrients. Diverse molecules have been produced in small quantities by engineered cyanobacteria to demonstrate the feasibility of photosynthetic biorefineries. Consequently, there is interest in engineering these microorganisms to increase titer and productivity to meet industrial metrics. Unfortunately, differing experimental conditions and cultivation techniques confound comparisons of strains and metabolic engineering strategies. In this work, we discuss the factors governing photoautotrophic growth and demonstrate nutritionally replete conditions in which a model cyanobacterium can be grown to stationary phase with light as the sole limiting substrate. We introduce a mathematical framework for understanding the dynamics of growth and product secretion in light-limited cyanobacterial cultures. Using this framework, we demonstrate how cyanobacterial growth in differing experimental systems can be easily scaled by the volumetric photon delivery rate using the model organisms Synechococcus sp. strain PCC7002 and Synechococcus elongatus strain UTEX2973. We use this framework to predict scaled up growth and product secretion in 1L photobioreactors of two strains of Synechococcus PCC7002 engineered for production of l-lactate or L-lysine. The analytical framework developed in this work serves as a guide for future metabolic engineering studies of cyanobacteria to allow better comparison of experiments performed in different experimental systems and to further investigate the dynamics of growth and product secretion. Copyright © 2018 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

Bacillus velezensis sp. nov., a surfactant-producing bacterium isolated from the river Vélez in Málaga, southern Spain.

Science.gov (United States)

Ruiz-García, Cristina; Béjar, Victoria; Martínez-Checa, Fernando; Llamas, Inmaculada; Quesada, Emilia

2005-01-01

Two Gram-positive, endospore-forming bacterial strains, CR-502T and CR-14b, which produce surfactant molecules are described. Phenotypic tests and phylogenetic analyses showed these strains to be members of the genus Bacillus and related to the species Bacillus atrophaeus, Bacillus mojavensis, Bacillus subtilis, Bacillus vallismortis and Bacillus amyloliquefaciens, although they differ from these species in a number of phenotypic characteristics. DNA-DNA hybridization confirmed that they show less than 20 % hybridization with the above-mentioned species and therefore represent a novel species of Bacillus. The DNA G+C content is 46.4 mol% in strain CR-502T and 46.1 mol% in strain CR-14b. The main fatty acids in strain CR-502T are 15 : 0 anteiso (32.70 %), 15 : 0 iso (29.86 %) and 16 : 0 (13.41 %). The main quinone in strain CR-502T is MK-7 (96.6 %). In the light of the polyphasic evidence gathered in this study, it is proposed that these strains be classified as a novel species of the genus Bacillus, with the name Bacillus velezensis sp. nov. The type strain (CR-502T=CECT 5686T=LMG 22478T) was isolated from a brackish water sample taken from the river Vélez at Torredelmar in Málaga, southern Spain.

Biosurfactant-producing yeasts widely inhabit various vegetables and fruits.

Science.gov (United States)

Konishi, Masaaki; Maruoka, Naruyuki; Furuta, Yoshifumi; Morita, Tomotake; Fukuoka, Tokuma; Imura, Tomohiro; Kitamoto, Dai

2014-01-01

The isolation of biosurfactant-producing yeasts from food materials was accomplished. By a combination of a new drop collapse method and thin-layer chromatography, 48 strains were selected as glycolipid biosurfactant producers from 347 strains, which were randomly isolated from various vegetables and fruits. Of the producers, 69% were obtained from vegetables of the Brassica family. Of the 48 producers, 15 strains gave relatively high yields of mannosylerythritol lipids (MELs), and were identified as Pseudozyma yeasts. These strains produced MELs from olive oil at yields ranging from 8.5 to 24.3 g/L. The best yield coefficient reached 0.49 g/g as to the carbon sources added. Accordingly, MEL producers were isolated at high efficiency from various vegetables and fruits, indicating that biosurfactant producers are widely present in foods. The present results should facilitate their application in the food and related industries.

From lab to market: An integrated bioprocess design approach for new-to-nature biosurfactants produced by Starmerella bombicola.

Science.gov (United States)

Van Renterghem, Lisa; Roelants, Sophie L K W; Baccile, Niki; Uyttersprot, Katrijn; Taelman, Marie Claire; Everaert, Bernd; Mincke, Stein; Ledegen, Sam; Debrouwer, Sam; Scholtens, Kristel; Stevens, Christian; Soetaert, Wim

2018-05-01

Glycolipid microbial biosurfactants, such as sophorolipids (SLs), generate high industrial interest as 100% biobased alternatives for traditional surfactants. A well-known success story is the efficient SL producer Starmerella bombicola, which reaches titers well above 200 g/L. Recent engineering attempts have enabled the production of completely new types of molecules by S. bombicola, e.g. the bolaform SLs. Scale-up of bolaform SL production was performed at 150 L scale. The purified product was evaluated in detergent applications, as classic SLs are mostly applied in eco-friendly detergents. In this paper, we show that they can be used as green and non-irritant surfactants in for example (automatic) dishwashing applications. However, due to the presence of an ester function in the biosurfactant molecule a limited chemical stability at higher pH values (>6.5) was noticed, (therefore called 'non-symmetrical' (nsBola)) which, is a major drawback that will most likely inhibit market introduction. An integrated bioprocess design (IBPD) strategy was thus applied to resolve this issue. The strategy was to replace the fed fatty acids with fatty alcohols, to generate so-called "symmetrical bolaform (sBola) sophorosides (SSs)," containing two instead of one glycosidic bond. Next to a change in feeding strategy, the blocking of the fatty alcohols from metabolizing/oxidizing through the suggested ω-oxidation pathway was necessary. For the latter, two putative fatty alcohol oxidase genes (fao1 and fao2) were identified in the S. bombicola genome and deleted in the bolaform SL producing strain (ΔatΔsble). Shake flask experiments for these new strains (ΔatΔsbleΔfao1 and ΔatΔsbleΔfao2) were performed to evaluate if the fed fatty alcohols were directly implemented into the SL biosynthesis pathway. Indeed, sBola sophorosides (SSs) production up to 20 g/L was observed for the ΔatΔsbleΔfao1 strain. Unexpectedly, the ΔatΔsbleΔfao2 strain only produced minor

Strain of Fusarium oxysporum Isolated From Almond Hulls Produces Styrene and 7-Methyl-1,3,5-Cyclooctatriene as the Principal Volatile Components

Science.gov (United States)

An isolated strain of Fusarium oxysporum from the hulls of Prunus dulcis (sweet almond) was found to produce relatively large quantities of the hydrocarbons styrene and three isomers of 7-methyl-1,3,5-cyclooctatriene (MCOT). Production of styrene and MCOT was reproduced on small scale using potato d...

Characterization of α-amylase produced by the endophytic strain of ...

African Journals Online (AJOL)

Tuoyo Aghomotsegin

2016-07-13

Jul 13, 2016 ... enzyme was incubated for 10 min at room temperature with the ions. CaCl2, BaCl2 .... 37°C, with the enzyme being completely inactivated at the temperature of ... chemicals of the culture medium, ionize polar molecules,.

[EFFICIENCY OF INTRODUCING CAROTENE PRODUCING STRAINS BACILLUS SP. 1.1 AND B. AMYLOLIQUEFACIENS UCM B-5113 INTO THE CHIKENS DIET].

Science.gov (United States)

Nechypurenko, O O; Kharhota M A; Avdeeva, L V

2015-01-01

It was shown the efficiency of carotene producing strains Bacillus sp. 1.1 and B. amyloliquefaciens UCM B-5113 in the diet of chickens. Also it was detected the lowering of the quantitative content of bacterial genera Enterococcus, Staphylococcus, family Enterobacteriaceae in the gut after eating by chickens cross "H&N Brown Nick" fodder with strains Bacillus sp. 1.1 and B. amyloliquefaciens UCM B-5113 alone and in composition in quantities 1 x 10(10) CFU per 1 g of feed. On the 18th day after introduction of cultures Bacillus sp. 1.1, B. amyloliquefaciens UCM B-5113 and their composition in the diet of poultry we revealed the increasing of body weight by 21.6, 7.6 and 22.0%, respectively, comparesing to controls. Also due to Bacillus sp. 1.1 it was detected the restore of intestinal villous structures, tissues of spleen, liver and heart. We found the additive effect of the composition of the investigated strains of bacteria genus Bacillus to the chickens.

Isotope separation using vibrationally excited molecules

International Nuclear Information System (INIS)

Woodroffe, J.A.; Keck, J.C.

1979-01-01

Vibrational excitation of molecules having components of a selected isotope type is used to produce a conversion from vibrational to translational excitation of the molecules by collision with the molecules of a heavy carrier gas. The resulting difference in translaton between the molecules of the selected isotope type and all other molecules of the same compound permits their separate collection. When applied to uranium enrichment, a subsonic cryogenic flow of molecules of uranium hexafluoride in combination with an argon carrier gas is directed through a cooled chamber that is illuminated by laser radiaton tuned to vibrationally excite the uranium hexafluoride molecules of a specific uranium isotope. The excited molecules collide with carrier gas molecules, causing a conversion of the excitation energy into a translation of the excited molecule, which results in a higher thermal energy or diffusivity than that of the other uranium hexafluoride molecules. The flowing molecules including the excited molecules directly enter a set of cryogenically cooled channels. The higher thermal velocity of the excited molecules increases the probability of their striking a collector surface. The molecules which strike this surface immediately condense. After a predetermined thickness of molecules is collected on the surface, the flow of uranium hexafluoride is interrupted and the chamber heated to the point of vaporization of the collected hexafluoride, permitting its removal. (LL)

Branching structure and strain hardening of branched metallocene polyethylenes

International Nuclear Information System (INIS)

Torres, Enrique; Li, Si-Wan; Costeux, Stéphane; Dealy, John M.

2015-01-01

There have been a number of studies of a series of branched metallocene polyethylenes (BMPs) made in a solution, continuous stirred tank reactor (CSTR) polymerization. The materials studied vary in branching level in a systematic way, and the most highly branched members of the series exhibit mild strain hardening. An outstanding question is which types of branched molecules are responsible for strain hardening in extension. This question is explored here by use of polymerization and rheological models along with new data on the extensional flow behavior of the most highly branched members of the set. After reviewing all that is known about the effects of various branching structures in homogeneous polymers and comparing this with the structures predicted to be present in BMPs, it is concluded that in spite of their very low concentration, treelike molecules with branch-on-branch structure provide a large number of deeply buried inner segments that are essential for strain hardening in these polymers

Branching structure and strain hardening of branched metallocene polyethylenes

Energy Technology Data Exchange (ETDEWEB)

Torres, Enrique; Li, Si-Wan; Costeux, Stéphane; Dealy, John M., E-mail: john.dealy@mcgill.ca [Department of Chemical Engineering, McGill University, Montreal, Quebec H3A 0C4 (Canada)

2015-09-15

There have been a number of studies of a series of branched metallocene polyethylenes (BMPs) made in a solution, continuous stirred tank reactor (CSTR) polymerization. The materials studied vary in branching level in a systematic way, and the most highly branched members of the series exhibit mild strain hardening. An outstanding question is which types of branched molecules are responsible for strain hardening in extension. This question is explored here by use of polymerization and rheological models along with new data on the extensional flow behavior of the most highly branched members of the set. After reviewing all that is known about the effects of various branching structures in homogeneous polymers and comparing this with the structures predicted to be present in BMPs, it is concluded that in spite of their very low concentration, treelike molecules with branch-on-branch structure provide a large number of deeply buried inner segments that are essential for strain hardening in these polymers.

Exotic helium molecules; Molecules exotiques d'helium

Energy Technology Data Exchange (ETDEWEB)

Portier, M

2007-12-15

We study the photo-association of an ultracold cloud of magnetically trapped helium atoms: pairs of colliding atoms interact with one or two laser fields to produce a purely long range {sup 4}He{sub 2}(2{sup 3}S{sub 1}-2{sup 3}P{sub 0}) molecule, or a {sup 4}He{sub 2}(2{sup 3}S{sub 1}-2{sup 3}S{sub 1}) long range molecule. Light shifts in one photon photo-association spectra are measured and studied as a function of the laser polarization and intensity, and the vibrational state of the excited molecule. They result from the light-induced coupling between the excited molecule, and bound and scattering states of the interaction between two metastable atoms. Their analysis leads to the determination of the scattering length a = (7.2 {+-} 0.6) ruling collisions between spin polarized atoms. The two photon photo-association spectra show evidence of the production of polarized, long-range {sup 4}He{sub 2}(2{sup 3}S{sub 1}-2{sup 3}S{sub 1}) molecules. They are said to be exotic as they are made of two metastable atoms, each one carrying a enough energy to ionize the other. The corresponding lineshapes are calculated and decomposed in sums and products of Breit-Wigner and Fano profiles associated to one and two photon processes. The experimental spectra are fit, and an intrinsic lifetime {tau} = (1.4 {+-} 0.3) {mu}s is deduced. It is checked whether this lifetime could be limited by spin-dipole induced Penning autoionization. This interpretation requires that there is a quasi-bound state close to the dissociation threshold in the singlet interaction potential between metastable helium atoms for the theory to match the experiment. (author)

Role of cloned carotenoid genes expressed in Escherichia coli in protecting against inactivation by near-UV light and specific phototoxic molecules

International Nuclear Information System (INIS)

Tuveson, R.W.; Larson, R.A.; Kagan, J.

1988-01-01

Genes controlling carotenoid synthesis were cloned from Erwinia herbicola and expressed in an Escherichia coli strain. Carotenoids protect against high fluences of near-UV (NUV; 320 to 400 nm) but not against far-UV (200-300 nm). Protection of E. coli cells was not observed following treatment with either psoralen or 8-methoxypsoralen plus NUV. However, significant protection of cells producing carotenoids was observed with three photosensitizing molecules activated by NUV (alpha-terthienyl, harmine, and phenylheptatriyne) which are thought to have the membrane as an important lethal target. Protection of carotenoid-producing cells against inactivation was not observed with acridine orange plus visible light but was seen with toluidine blue O plus visible light

Bacteriocin-producing Enterococci from Rabbit Meat

Directory of Open Access Journals (Sweden)

Szabóová, R.

2012-01-01

Full Text Available Aims: Enterococci are lactic acid bacteria belonging to the division Firmicutes. They occur in different ecosystems, rabbits including. Enterococci can possess probiotic properties and produce antimicrobial substances-bacteriocins. Rabbit meat as nutritionally healthy food offers novel source to study bacteriocin-producing and/or probiotic enterococci. Methodology and results: Enterococci were detected from rabbit meat samples (42. Most of the isolates were allotted to the species Enterococcus faecium by PCR method. The isolates have possessed the structural genes for enterocins A, P, B production. The inhibitory substances produced by the isolated enterococci inhibited the growth of 12 indicators. Of 34 isolates, 15 strains have shown the antimicrobial activity against L. monocytogenes CCM 4699, 12 strains against S. aureus 3A3, 10 strains against S. aureus 5A2 as well as Salmonella enterica serovar Enteritidis PT4. Moreover, enterococci have tolerated 5 % bile, low pH; they have produced lactid acid in the amount from 0.740 ± 0.091 to 1.720 ± 0.095 mmol/l. The isolates were mostly sensitive to antibiotics. Conclusion, significance and impact of study: Bacteriocin-producing strain E. faecium M3a has been selected for more detail characterization of its bacteriocin and probiotic properties with the aim for its further application as an additive.

The importance of Bordetella pertussis strains which do not produce virulence factors in the epidemiology of pertussis

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Maciej Polak

2017-05-01

Full Text Available Bordetella pertussis strains, which have lost the ability to produce antigens, such as pertactin - Prn, pertussis toxin - Ptx, filamentous haemagglutinin - FHA, fimbriae type 2 and 3 - Fim 2 and 3, tracheal colonization factor - TcfA, have recently been isolated in countries with a high vaccination coverage. The emergence of such isolates might have resulted from B. pertussis natural evolution course or adaptive mechanisms, allowing increased circulation of the pathogen in vaccinated populations. So far, the majority of described mutants were deficient in the Prn production. Prn deficient isolates were found in countries which use acellular pertussis vaccines (aP in routine immunization programmes. The increase of frequency of Prn¯ strains isolation was correlated with the period of routine vaccination with aP vaccines. In most countries, the spread of these isolates has resulted from independent mutations rather than from the expansion of a single clone. Prn¯ isolates were collected from patients showing typical clinical symptoms of pertussis found for Prn+ strains. Results of in vitro and in vivo studies have shown that Prn¯, Ptx¯ and FHA¯ isolates retain cytotoxic properties, and besides Ptx¯ isolates, were lethal in intranasally infected mice. Further explanation of the impact of antigen deficiencies on virulence and transmission of B. pertussis in the context of the continuous increase of pertussis incidence is necessary to develop a new, optimized strategy of pertussis prevention.

A closer look at prion strains

Science.gov (United States)

Solforosi, Laura; Milani, Michela; Mancini, Nicasio; Clementi, Massimo; Burioni, Roberto

2013-01-01

Prions are infectious proteins that are responsible for transmissible spongiform encephalopathies (TSEs) and consist primarily of scrapie prion protein (PrPSc), a pathogenic isoform of the host-encoded cellular prion protein (PrPC). The absence of nucleic acids as essential components of the infectious prions is the most striking feature associated to these diseases. Additionally, different prion strains have been isolated from animal diseases despite the lack of DNA or RNA molecules. Mounting evidence suggests that prion-strain-specific features segregate with different PrPSc conformational and aggregation states. Strains are of practical relevance in prion diseases as they can drastically differ in many aspects, such as incubation period, PrPSc biochemical profile (e.g., electrophoretic mobility and glycoform ratio) and distribution of brain lesions. Importantly, such different features are maintained after inoculation of a prion strain into genetically identical hosts and are relatively stable across serial passages. This review focuses on the characterization of prion strains and on the wide range of important implications that the study of prion strains involves. PMID:23357828

Strain comparisons in aquaculture species: a manual

OpenAIRE

Ponzoni, R.W.; James, J.W.; Nguyen, N.H.; Mekkawy, W.; Khaw, H.L.

2013-01-01

When different strains or breeds of a particular species are available, the best choice is seldom immediately obvious for producers. Scientists are also interested in the relative performance of different strains because it provides a basis for recommendations to producers and it often stimulates the conduct of work aimed at unraveling the underlying biological mechanisms involved in the expression of such differences. Hence, strain or breed comparisons of some sort are frequently conducted. ...

Exopolysaccharide-producing Bifidobacterium animalis subsp. lactis strains and their polymers elicit different responses on immune cells from blood and gut associated lymphoid tissue.

Science.gov (United States)

Hidalgo-Cantabrana, Claudio; Nikolic, Milica; López, Patricia; Suárez, Ana; Miljkovic, Marija; Kojic, Milan; Margolles, Abelardo; Golic, Natasa; Ruas-Madiedo, Patricia

2014-04-01

The effect of exopolysaccharide (EPS) producing bifidobacteria, and the EPS derived thereof, on the modulation of immune response was evaluated. Cells isolated from gut associated lymphoid tissue (GALT) and from peripheral blood mononuclear cells (PBMC) of naïve rats were used. The proliferation and cytokine production of these immune cells in the presence of the three isogenic Bifidobacterium animalis subsp. lactis strains (A1, A1dOx and A1dOxR), as well as their purified polymers, were in vitro analysed. The cytokine pattern produced by immune cells isolated from GALT showed that most levels remained stable in the presence of the three strains or their corresponding polymers. However, in PBMC the UV-inactivated bacteria induced higher levels of the ratios IFNγ/IL-17, TNFα/IL-10 and TNFα/TGFβ, and no variation in the ratio IFNγ/IL-4. Thus, B. animalis subsp. lactis strains were able to activate blood monocytes as well as T lymphocytes towards a mild inflammatory Th1 response. Furthermore, only the EPS-A1dOxR was able to stimulate a response in a similar way than its EPS-producing bacterium. Our work supports the notion that some bifidobacterial EPS could play a role in mediating the dialog of these microorganisms with the immune system. In addition, this study emphasizes the effect that the origin of the immune cells has in results obtained; this could explain the great amount of contradiction found in literature about the immunomodulation capability of EPS from probiotic bacteria. Copyright © 2014 Elsevier Ltd. All rights reserved.

Biopesticide activity of sugarcane associated rhizobacteria: Ochrobactrum intermedium strain NH-5 and Stenotrophomonas maltophilia strain NH-300 against red rot under field conditions

Directory of Open Access Journals (Sweden)

Muhammad Nadeem HASSAN

2014-09-01

Full Text Available Colletotrichum falcatum is the major fungal pathogen causing sugarcane red rot. Four antagonistic bacterial strains exhibiting biocontrol activity against this pathogen in greenhouse conditions were characterized for production of different antifungal metabolites and biocontrol determinants to elucidate the mechanism of action involved in their antagonistic activity. The strains were also evaluated under field conditions to assess their biocontrol potential. All the strains produced hydrogen cyanide (HCN, and volatile and diffusible antibiotics. In addition, the Ochrobactrum intermedium strain NH-5 produced siderophores and the broad spectrum antibiotic 2, 4-diacetylphloroglucinol (2,4-DAPG; Pseudomonas sp. NH-203 produced siderophores, and Pseudomonas sp. NH-276 produced protease. Two strains, Ochrobactrum intermedium NH-5 and Stenotrophomonas maltophilia NH-300, exhibited good biocontrol activity, suppressing red rot by 44–52% on two sugarcane varieties, SPF-234 and Co-1148, in field experiments. The strains gave consistent results in three consecutive years and showed potential to be used as biopesticides.

Strain and water effects on the electronic structure and chemical activity of in-plane graphene/silicene heterostructure

Science.gov (United States)

Kistanov, Andrey A.; Cai, Yongqing; Zhang, Yong-Wei; Dmitriev, Sergey V.; Zhou, Kun

2017-03-01

By using first-principles calculations, the electronic structure of planar and strained in-plane graphene/silicene heterostructure is studied. The heterostructure is found to be metallic in a strain range from  -7% (compression) to  +7% (tension). The effect of compressive/tensile strain on the chemical activity of the in-plane graphene/silicene heterostructure is examined by studying its interaction with the H2O molecule. It shows that compressive/tensile strain is able to increase the binding energy of H2O compared with the adsorption on a planar surface, and the charge transfer between the water molecule and the graphene/silicene sheet can be modulated by strain. Moreover, the presence of the boron-nitride (BN)-substrate significantly influences the chemical activity of the graphene/silicene heterostructure upon its interaction with the H2O molecule and may cause an increase/decrease of the charge transfer between the H2O molecule and the heterostructure. These findings provide insights into the modulation of electronic properties of the in-plane free-standing/substrate-supported graphene/silicene heterostructure, and render possible ways to control its electronic structure, carrier density and redox characteristics, which may be useful for its potential applications in nanoelectronics and gas sensors.

Strain and water effects on the electronic structure and chemical activity of in-plane graphene/silicene heterostructure

International Nuclear Information System (INIS)

Kistanov, Andrey A; Zhou, Kun; Cai, Yongqing; Zhang, Yong-Wei; Dmitriev, Sergey V

2017-01-01

By using first-principles calculations, the electronic structure of planar and strained in-plane graphene/silicene heterostructure is studied. The heterostructure is found to be metallic in a strain range from  −7% (compression) to  +7% (tension). The effect of compressive/tensile strain on the chemical activity of the in-plane graphene/silicene heterostructure is examined by studying its interaction with the H 2 O molecule. It shows that compressive/tensile strain is able to increase the binding energy of H 2 O compared with the adsorption on a planar surface, and the charge transfer between the water molecule and the graphene/silicene sheet can be modulated by strain. Moreover, the presence of the boron-nitride (BN)-substrate significantly influences the chemical activity of the graphene/silicene heterostructure upon its interaction with the H 2 O molecule and may cause an increase/decrease of the charge transfer between the H 2 O molecule and the heterostructure. These findings provide insights into the modulation of electronic properties of the in-plane free-standing/substrate-supported graphene/silicene heterostructure, and render possible ways to control its electronic structure, carrier density and redox characteristics, which may be useful for its potential applications in nanoelectronics and gas sensors. (paper)

Enantiomeric separation of complex organic molecules produced from irradiation of interstellar/circumstellar ice analogs

Science.gov (United States)

Nuevo, M.; Meierhenrich, U. J.; D'Hendecourt, L.; Muñoz Caro, G. M.; Dartois, E.; Deboffle, D.; Thiemann, W. H.-P.; Bredehöft, J.-H.; Nahon, L.

Irradiation of interstellar/circumstellar ice analogs by ultraviolet (UV) light followed by warm up in the laboratory leads to the formation of complex organic molecules, stable at room temperature. Hydrolysis of the room temperature residue releases amino acids, the building blocks of proteins. These amino acids exist in two different forms (L and D), but proteins encountered in living beings consist exclusively of L enantiomers. The origin of this property, called homochirality, is still unknown. Amino acids can be detected and quantified by chemical techniques such as chiral gas chromatography coupled with mass spectrometry (GC-MS). Enantiomers of chiral organics are also known to interact selectively with circularly polarized light (CPL), leading to a selective production or destruction of the final compounds. This paper describes how we settled an experiment where amino acids are formed by irradiation of interstellar/circumstellar ice analogs with ultraviolet (UV) CPL, produced by a synchrotron radiation beamline, which allowed us to quantify the effect of such polarized light on the production of amino acids. These results can be compared to the enantiomeric excesses measured in primitive meteorites such as Murchison.

NEW STRAIN PRODUCERS OF BIOBUTANOL. III. METHODS OF INCREASED BUTANOL ACCUMULATION FROM BIOMASS OF SWITCHGRASS Panicum virgatum L.

Directory of Open Access Journals (Sweden)

Tigunova O. O.

2015-08-01

Full Text Available The aim of this work was to enlarge accumulation of butanol from switchgrass Panicum virgatum L. biomass using strains-producers obtained from grounds and silts of Kyiv lakes. The objects of the study were strains of C. acetobutylicum ІМВ B-7407 (IFBG C6H, Clostridium acetobutylicum IFBG C6H 5М and Clostridium tyrobutyricum IFBG C4B from the "Collections of microbial strains and lines of plants for food and agricultural biotechnology" of the Public Institution "Institute of Food Biotechnology and Genomics" of the National Academy of Sciences of Ukraine. Gas chromatography was used to determine the alcohol concentration at the stage of solvent synthesis. To determine the effect of butanol precursors during cultivation, butyric, lactic and acetic acids were used. Optimization of processing parameters, which was based on the needs of cultures, allowed us to increase the yield by 20 and 50% for the initial and mutant strain respectively. Using synthetic precursors (such as lactic, butyric and acetic acid during cultivation increased total concentration of butanol by 1.7 times. To optimize the process, a study was carried out using acetone- butyl grains. Using of acetone-butyl grains in concentrations up to 60% does not affect the synthesis of butanol by C. acetobutylicum IFBG C6H 5M. Increasing the concentration of grains led to decrease in accumulation of butanol. Almost double increase in accumulation of the target product (butanol was achieved using two-stage fermentation and/or precursors of synthesis. It was shown the possibility of using acetone-butyl grains in fermentation. As a result the mass fraction of the waste was reduced.

Characterization of N-Acylhomoserine Lactones Produced by Bacteria Isolated from Industrial Cooling Water Systems

Directory of Open Access Journals (Sweden)

Noriya Okutsu

2015-12-01

Full Text Available The cooling water systems are used to remove heat generated in the various industries. Biofouling of the cooling water systems causes blocking of condenser pipes and the heat exchanger tubes. In many Gram-negative bacteria, N-acylhomoserine lactone (AHL are used as quorum-sensing signal molecule and associated with biofilm formation. To investigate the relationship between quorum sensing and biofouling in the cooling water system, we isolated a total of 192 bacterial strains from the five cooling water systems, and screened for AHL production. Seven isolates stimulated AHL-mediated purple pigment production in AHL reporter strain Chromobacterium violaceum CV026 or VIR07. Based on their 16S rRNA gene sequences, AHL-producing isolates were assigned to Aeromonas hydrophila, Lysobacter sp., Methylobacterium oryzae, and Bosea massiliensis. To the best of our knowledge, B. massiliensis and Lysobacter sp. have not been reported as AHL-producing species in the previous researches. AHLs extracted from the culture supernatants of B. massiliensis and Lysobacter sp. were identified by liquid chromatography-mass spectrometry. AHLs produced by B. massiliensis were assigned as N-hexanoyl-l-homoserine lactone (C6-HSL, N-(3-oxohexanoyl-l-homoserine lactone (3-oxo-C6-HSL, and N-(3-oxooctanoyl-l-homoserine lactone (3-oxo-C8-HSL. AHLs produced by Lysobacter sp. were assigned as N-decanoyl-l-homoserine lactone (C10-HSL and N-(3-oxodecanoyl-l-homoserine lactone (3-oxo-C10-HSL. This is the first report of identification of AHLs produced by B. massiliensis and Lysobacter sp. isolated from the cooling water system.

Characterization and properties of biosurfactants produced by a newly isolated strain Bacillus methylotrophicus DCS1 and their applications in enhancing solubility of hydrocarbon.

Science.gov (United States)

Jemil, Nawel; Ben Ayed, Hanen; Hmidet, Noomen; Nasri, Moncef

2016-11-01

Six biosurfactant-producing bacteria were isolated from hydrocarbon contaminated soils in Sfax, Tunisia. Isolates were screened for biosurfactant production by different conventional methods including hemolytic activity, surface tension reduction, drop-collapsing and oil displacement tests. All these screening tests show that all the isolates behave differently. Among the isolated bacteria, DCS1 strain was selected for further studies based on its highest activities and it was identified as Bacillus methylotrophicus DCS1. This strain was found to be a potent producer of biosurfactant when cultivated in mineral-salts medium supplemented with diesel oil (2 %, v/v) as a sole carbon source. Physicochemical properties and stability of biosurfactants synthesized by B. methylotrophicus DCS1 were investigated. The produced biosurfactants DCS1, from Landy medium, possess high surface activity that could lower the surface tension of water to a value of 31 from 72 mN m(-1) and have a critical micelle concentration (CMC) of 100 mg L(-1). Compared with SDS and Tween 80, biosurfactants showed excellent emulsification activities against different hydrocarbon substrates and high solubilization efficiency towards diesel oil. Biosurfactants DCS1 showed good stability in a wide range of temperature, pH and salinity. These results suggested that biosurfactants produced by B. methylotrophicus DCS1 could be an alternative to chemically synthesized surfactants for use in bioremediation processes to enhance the solubility of hydrophobic compounds.

Comparative genomics of citric-acid-producing Aspergillus niger ATCC 1015 versus enzyme-producing CBS 513.88

Science.gov (United States)

Andersen, Mikael R.; Salazar, Margarita P.; Schaap, Peter J.; van de Vondervoort, Peter J.I.; Culley, David; Thykaer, Jette; Frisvad, Jens C.; Nielsen, Kristian F.; Albang, Richard; Albermann, Kaj; Berka, Randy M.; Braus, Gerhard H.; Braus-Stromeyer, Susanna A.; Corrochano, Luis M.; Dai, Ziyu; van Dijck, Piet W.M.; Hofmann, Gerald; Lasure, Linda L.; Magnuson, Jon K.; Menke, Hildegard; Meijer, Martin; Meijer, Susan L.; Nielsen, Jakob B.; Nielsen, Michael L.; van Ooyen, Albert J.J.; Pel, Herman J.; Poulsen, Lars; Samson, Rob A.; Stam, Hein; Tsang, Adrian; van den Brink, Johannes M.; Atkins, Alex; Aerts, Andrea; Shapiro, Harris; Pangilinan, Jasmyn; Salamov, Asaf; Lou, Yigong; Lindquist, Erika; Lucas, Susan; Grimwood, Jane; Grigoriev, Igor V.; Kubicek, Christian P.; Martinez, Diego; van Peij, Noël N.M.E.; Roubos, Johannes A.; Nielsen, Jens; Baker, Scott E.

2011-01-01

The filamentous fungus Aspergillus niger exhibits great diversity in its phenotype. It is found globally, both as marine and terrestrial strains, produces both organic acids and hydrolytic enzymes in high amounts, and some isolates exhibit pathogenicity. Although the genome of an industrial enzyme-producing A. niger strain (CBS 513.88) has already been sequenced, the versatility and diversity of this species compel additional exploration. We therefore undertook whole-genome sequencing of the acidogenic A. niger wild-type strain (ATCC 1015) and produced a genome sequence of very high quality. Only 15 gaps are present in the sequence, and half the telomeric regions have been elucidated. Moreover, sequence information from ATCC 1015 was used to improve the genome sequence of CBS 513.88. Chromosome-level comparisons uncovered several genome rearrangements, deletions, a clear case of strain-specific horizontal gene transfer, and identification of 0.8 Mb of novel sequence. Single nucleotide polymorphisms per kilobase (SNPs/kb) between the two strains were found to be exceptionally high (average: 7.8, maximum: 160 SNPs/kb). High variation within the species was confirmed with exo-metabolite profiling and phylogenetics. Detailed lists of alleles were generated, and genotypic differences were observed to accumulate in metabolic pathways essential to acid production and protein synthesis. A transcriptome analysis supported up-regulation of genes associated with biosynthesis of amino acids that are abundant in glucoamylase A, tRNA-synthases, and protein transporters in the protein producing CBS 513.88 strain. Our results and data sets from this integrative systems biology analysis resulted in a snapshot of fungal evolution and will support further optimization of cell factories based on filamentous fungi. PMID:21543515

OMG: Open molecule generator

NARCIS (Netherlands)

Peironcely, J.E.; Rojas-Chertó, M.; Fichera, D.; Reijmers, T.; Coulier, L.; Faulon, J.-L.; Hankemeier, T.

2012-01-01

Computer Assisted Structure Elucidation has been used for decades to discover the chemical structure of unknown compounds. In this work we introduce the first open source structure generator, Open Molecule Generator (OMG), which for a given elemental composition produces all non-isomorphic chemical

Intracellular synthesis of glutamic acid in Bacillus methylotrophicus SK19.001, a glutamate-independent poly(γ-glutamic acid)-producing strain.

Science.gov (United States)

Peng, Yingyun; Zhang, Tao; Mu, Wanmeng; Miao, Ming; Jiang, Bo

2016-01-15

Bacillus methylotrophicus SK19.001 is a glutamate-independent strain that produces poly(γ-glutamic acid) (γ-PGA), a polymer of D- and L-glutamic acids that possesses applications in food, the environment, agriculture, etc. This study was undertaken to explore the synthetic pathway of intracellular L- and D-glutamic acid in SK19.001 by investigating the effects of tricarboxylic acid cycle intermediates and different amino acids as metabolic precursors on the production of γ-PGA and analyzing the activities of the enzymes involved in the synthesis of L- and D-glutamate. Tricarboxylic acid cycle intermediates and amino acids could participate in the synthesis of γ-PGA via independent pathways in SK19.001. L-Aspartate aminotransferase, L-glutaminase and L-glutamate synthase were the enzymatic sources of L-glutamate. Glutamate racemase was responsible for the formation of D-glutamate for the synthesis of γ-PGA, and the synthetase had stereoselectivity for glutamate substrate. The enzymatic sources of L-glutamate were investigated for the first time in the glutamate-independent γ-PGA-producing strain, and multiple enzymatic sources of L-glutamate were verified in SK19.001, which will benefit efforts to improve production of γ-PGA with metabolic engineering strategies. © 2015 Society of Chemical Industry.

Isolation and molecular characterization of phytase producing ...

African Journals Online (AJOL)

Isolation and molecular characterization of phytase producing bacteria from Malaysia hot springs. ... The strains were further analyzed in broth culture using sodium phytate as substrate. Among them, strain L3 was selected as the best producer (0.16 U/ml after 72 h of culture). This phytase showed optimal activity at 37 °C ...

Complete genome sequence of N2-fixing model strain Klebsiella sp. nov. M5al, which produces plant cell wall-degrading enzymes and siderophores

Directory of Open Access Journals (Sweden)

Zhili Yu

2018-03-01

Full Text Available The bacterial strain M5al is a model strain for studying the molecular genetics of N2-fixation and molecular engineering of microbial production of platform chemicals 1,3-propanediol and 2,3-butanediol. Here, we present the complete genome sequence of the strain M5al, which belongs to a novel species closely related to Klebsiella michiganensis. M5al secretes plant cell wall-degrading enzymes and colonizes rice roots but does not cause soft rot disease. M5al also produces siderophores and contains the gene clusters for synthesis and transport of yersiniabactin which is a critical virulence factor for Klebsiella pathogens in causing human disease. We propose that the model strain M5al can be genetically modified to study bacterial N2-fixation in association with non-legume plants and production of 1,3-propanediol and 2,3-butanediol through degradation of plant cell wall biomass.

Technological characterization and survival of the exopolysaccharide-producing strain Lactobacillus delbrueckii subsp. lactis 193 and its bile-resistant derivative 193+ in simulated gastric and intestinal juices.

Science.gov (United States)

Burns, Patricia; Vinderola, Gabriel; Reinheimer, Jorge; Cuesta, Isabel; de Los Reyes-Gavilán, Clara G; Ruas-Madiedo, Patricia

2011-08-01

The capacity of lactic acid bacteria to produce exopolysaccharides (EPS) conferring microorganisms a ropy phenotype could be an interesting feature from a technological point of view. Progressive adaptation to bile salts might render some lactobacilli able to overcome physiological gut barriers but could also modify functional properties of the strain, including the production of EPS. In this work some technological properties and the survival ability in simulated gastrointestinal conditions of Lactobacillus delbrueckii subsp. lactis 193, and Lb. delbrueckii subsp. lactis 193+, a strain with stable bile-resistant phenotype derived thereof, were characterized in milk in order to know whether the acquisition of resistance to bile could modify some characteristics of the microorganism. Both strains were able to grow and acidify milk similarly; however the production of ethanol increased at the expense of the aroma compound acetaldehyde in milk fermented by the strain 193+, with respect to milk fermented by the strain 193. Both microorganisms produced a heteropolysaccharide composed of glucose and galactose, and were able to increase the viscosity of fermented milks. In spite of the higher production yield of EPS by the bile-resistant strain 193+, it displayed a lower ability to increase viscosity than Lb. delbrueckii subsp. lactis 193. Milk increased survival in simulated gastric juice; the presence of bile improved adhesion to the intestinal cell line HT29-MTX in both strains. However, the acquisition of a stable resistance phenotype did not improve survival in simulated gastric and intestinal conditions or the adhesion to the intestinal cell line HT29-MTX. Thus, Lb. delbrueckii subsp. lactis 193 presents suitable technological properties for the manufacture of fermented dairy products; the acquisition of a stable bile-resistant phenotype modified some properties of the microorganism. This suggests that the possible use of bile-resistant derivative strains should be

Genomic analysis of thermophilic Bacillus coagulans strains: efficient producers for platform bio-chemicals.

Science.gov (United States)

Su, Fei; Xu, Ping

2014-01-29

Microbial strains with high substrate efficiency and excellent environmental tolerance are urgently needed for the production of platform bio-chemicals. Bacillus coagulans has these merits; however, little genetic information is available about this species. Here, we determined the genome sequences of five B. coagulans strains, and used a comparative genomic approach to reconstruct the central carbon metabolism of this species to explain their fermentation features. A novel xylose isomerase in the xylose utilization pathway was identified in these strains. Based on a genome-wide positive selection scan, the selection pressure on amino acid metabolism may have played a significant role in the thermal adaptation. We also researched the immune systems of B. coagulans strains, which provide them with acquired resistance to phages and mobile genetic elements. Our genomic analysis provides comprehensive insights into the genetic characteristics of B. coagulans and paves the way for improving and extending the uses of this species.

Strain-induced friction anisotropy between graphene and molecular liquids

Science.gov (United States)

Liao, Meng; To, Quy-Dong; Léonard, Céline; Monchiet, Vincent; Vo, Van-Hoang

2017-01-01

In this paper, we study the friction behavior of molecular liquids with anisotropically strained graphene. Due to the changes of lattice and the potential energy surface, the friction is orientation dependent and can be computed by tensorial Green-Kubo formula. Simple quantitative estimations are also proposed for the zero-time response and agree reasonably well with the molecular dynamics results. From simulations, we can obtain the information of structures, dynamics of the system, and study the influence of strain and molecular shapes on the anisotropy degree. It is found that unilateral strain can increase friction in all directions but the strain direction is privileged. Numerical evidences also show that nonspherical molecules are more sensitive to strain and give rise to more pronounced anisotropy effects.

The use of lactic acid-producing, malic acid-producing, or malic acid-degrading yeast strains for acidity adjustment in the wine industry.

Science.gov (United States)

Su, Jing; Wang, Tao; Wang, Yun; Li, Ying-Ying; Li, Hua

2014-03-01

In an era of economic globalization, the competition among wine businesses is likely to get tougher. Biotechnological innovation permeates the entire world and intensifies the severity of the competition of the wine industry. Moreover, modern consumers preferred individualized, tailored, and healthy and top quality wine products. Consequently, these two facts induce large gaps between wine production and wine consumption. Market-orientated yeast strains are presently being selected or developed for enhancing the core competitiveness of wine enterprises. Reasonable biological acidity is critical to warrant a high-quality wine. Many wild-type acidity adjustment yeast strains have been selected all over the world. Moreover, mutation breeding, metabolic engineering, genetic engineering, and protoplast fusion methods are used to construct new acidity adjustment yeast strains to meet the demands of the market. In this paper, strategies and concepts for strain selection or improvement methods were discussed, and many examples based upon selected studies involving acidity adjustment yeast strains were reviewed. Furthermore, the development of acidity adjustment yeast strains with minimized resource inputs, improved fermentation, and enological capabilities for an environmentally friendly production of healthy, top quality wine is presented.

Genetic recombination in auxotrophic strains of Phanerochaete chrysosporium

International Nuclear Information System (INIS)

Krejci, R.

1987-01-01

Four auxotrophic strains of ligninolytic basidiomycete Phanerochaete chrysosporium were obtained by UV mutagenesis. The heterokaryotic mycelium formed by complementation of different auxotrophic isolates was able to fruit and produce basidiospores. Prototrophic strains and strains with a recombined set of parental nutritional requirements were isolated from the basidiospore progeny of the heterokaryons. Genetic recombination hence takes place in fruit bodies produced by the heterokaryotic mycelium. (author). 3 tabs., 13 refs

Exotic helium molecules; Molecules exotiques d'helium

Energy Technology Data Exchange (ETDEWEB)

Portier, M

2007-12-15

We study the photo-association of an ultracold cloud of magnetically trapped helium atoms: pairs of colliding atoms interact with one or two laser fields to produce a purely long range {sup 4}He{sub 2}(2{sup 3}S{sub 1}-2{sup 3}P{sub 0}) molecule, or a {sup 4}He{sub 2}(2{sup 3}S{sub 1}-2{sup 3}S{sub 1}) long range molecule. Light shifts in one photon photo-association spectra are measured and studied as a function of the laser polarization and intensity, and the vibrational state of the excited molecule. They result from the light-induced coupling between the excited molecule, and bound and scattering states of the interaction between two metastable atoms. Their analysis leads to the determination of the scattering length a = (7.2 {+-} 0.6) ruling collisions between spin polarized atoms. The two photon photo-association spectra show evidence of the production of polarized, long-range {sup 4}He{sub 2}(2{sup 3}S{sub 1}-2{sup 3}S{sub 1}) molecules. They are said to be exotic as they are made of two metastable atoms, each one carrying a enough energy to ionize the other. The corresponding lineshapes are calculated and decomposed in sums and products of Breit-Wigner and Fano profiles associated to one and two photon processes. The experimental spectra are fit, and an intrinsic lifetime {tau} = (1.4 {+-} 0.3) {mu}s is deduced. It is checked whether this lifetime could be limited by spin-dipole induced Penning autoionization. This interpretation requires that there is a quasi-bound state close to the dissociation threshold in the singlet interaction potential between metastable helium atoms for the theory to match the experiment. (author)

Formation of ultracold NaRb Feshbach molecules

International Nuclear Information System (INIS)

Wang, Fudong; He, Xiaodong; Li, Xiaoke; Zhu, Bing; Chen, Jun; Wang, Dajun

2015-01-01

We report the creation of ultracold bosonic 23 Na 87 Rb Feshbach molecules via magneto-association. By ramping the magnetic field across an interspecies Feshbach resonance (FR), at least 4000 molecules can be produced out of the near degenerate ultracold mixture. Fast loss due to inelastic atom–molecule collisions is observed, which limits the pure molecule number, after residual atoms removal, to 1700. The pure molecule sample can live for 21.8(8) ms in the optical trap, long enough for future molecular spectroscopy studies toward coherently transferring to the singlet ro-vibrational ground state, where these molecules are stable against chemical reaction and have a permanent electric dipole moment of 3.3 Debye. We have also measured the Feshbach molecule’s binding energy near the FR by the oscillating magnetic field method and found these molecules have a large closed-channel fraction. (paper)

Penicillin production by mutant strains of penicillium chrysogenum

International Nuclear Information System (INIS)

Tawfik, Z.S.; Ashour, M.S.; Shihab, A.

1986-01-01

The mutagenic agent 8-rays was used to initiate the penicillium chrysogenum isolated from local spices. After irradiation, colonies invariably differing from the parent strain in their morphological and cultural characteristics were tested for antibiotic production on fermentation agar medium. Twenty two isolates were found to be penicillin producing mutant strains. Mutant strain M 24 forming small colonies with white conidia was found to be a high yielding penicillin producer (9550 i.u/ml). All of the 22 isolates obtained lost their ability to produce the antibiotic after 11 months storage at 4 0 with subsequent subculturing

Microbial diversity of mangrove sediment in Shenzhen Bay and gene cloning, characterization of an isolated phytase-producing strain of SPC09 B. cereus.

Science.gov (United States)

Zhang, Shengpeng; Liao, Shao-An; Yu, Xiaoyuan; Lu, Hongwu; Xian, Jian-An; Guo, Hui; Wang, Anli; Xie, Jian

2015-06-01

Phytases hydrolyze phytate to release inorganic phosphate, which decreases the requirement for phosphorus in fertilizers for crops and thus reduces environmental pollutants. This study analyzed microbial communities in rhizosphere sediment, collected in September 2012 from Shenzhen Bay, Guangdong, China, using high-throughput pyrosequencing; the results showed that the dominant taxonomic phyla were Chloroflexi, Firmicutes, and Proteobacteria, and the proportion of the beneficial bacteria, Bacillus, was 4.95 %. Twenty-nine culturable, phytase-producing bacteria were isolated, their phosphorus solubilization capacity was analyzed, and they were taxonomically characterized. Their phylogenetic placement was determined using 16S ribosomal RNA (rRNA) gene sequence analysis. The result shows that most of the isolates are members of the order Bacillales, although seven strains of Enterobacteriales, two strains of Pseudomonadales, and one strain of Oceanospirillales were also identified. The phytase gene was cloned from SPC09, Bacillus cereus, which showed the highest phosphorus solubilizing ability among the isolated strains. The gene encoded a primary translation product of 335 amino acids. A construct including the 1005-nt ORF fragment, Bc-phy, was transformed into Escherichia coli. The recombinant phytase was produced and purified, which revealed the temperature optima at 60 °C and pH optima at 6.5. The assessment by quantitative PCR (qPCR) showed an abundance of bacteria containing the Bc-phy gene; the level was generally higher in the mangrove forest than in the tidal flats and in surface soil compared to bottom soil, and the highest value was obtained in June. Herein, we report on the cloning, characterization, and activity of a novel phytase isolated from a mangrove system.

Immune Modulating Capability of Two Exopolysaccharide-Producing Bifidobacterium Strains in a Wistar Rat Model

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Nuria Salazar

2014-01-01

Full Text Available Fermented dairy products are the usual carriers for the delivery of probiotics to humans, Bifidobacterium and Lactobacillus being the most frequently used bacteria. In this work, the strains Bifidobacterium animalis subsp. lactis IPLA R1 and Bifidobacterium longum IPLA E44 were tested for their capability to modulate immune response and the insulin-dependent glucose homeostasis using male Wistar rats fed with a standard diet. Three intervention groups were fed daily for 24 days with 10% skimmed milk, or with 109 cfu of the corresponding strain suspended in the same vehicle. A significant increase of the suppressor-regulatory TGF-β cytokine occurred with both strains in comparison with a control (no intervention group of rats; the highest levels were reached in rats fed IPLA R1. This strain presented an immune protective profile, as it was able to reduce the production of the proinflammatory IL-6. Moreover, phosphorylated Akt kinase decreased in gastroctemius muscle of rats fed the strain IPLA R1, without affecting the glucose, insulin, and HOMA index in blood, or levels of Glut-4 located in the membrane of muscle and adipose tissue cells. Therefore, the strain B. animalis subsp. lactis IPLA R1 is a probiotic candidate to be tested in mild grade inflammation animal models.

Lipid composition in a strain of Bacillus subtilis, a producer of iturin A lipopeptides that are active against uropathogenic bacteria.

Science.gov (United States)

Bernat, Przemysław; Paraszkiewicz, Katarzyna; Siewiera, Paulina; Moryl, Magdalena; Płaza, Grażyna; Chojniak, Joanna

2016-10-01

Urinary tract infections are a common disease in humans. Therefore, new methods are needed to destroy biofilms that are formed by uropathogens. Iturin A lipopeptides (LPs) C14 and C15 are potent biosurfactants synthetized by the Bacillus subtilis I'1a strain. The biological activity of extracted LPs was confirmed by examining extracts from I'1a cultures against uropathogenic bacteria that had been isolated from biofilms on urinary catheters. Compared with cultures of DSM 3257, which produce surfactin at a relatively low level, the extract obtained from strain I'1a exhibited a greater inhibitory effect against both planktonic and sessile forms of Escherichia coli, Serratia marcescens, Enterobacter cloacae, Proteus mirabilis, Citrobacter freundii and Enterococcus faecalis. Moreover, cyclic LP biosurfactants may disturb the integrity of cytoplasmic membranes; therefore, we investigated the effects of synthetized LPs on fatty acids and phospholipids of B. subtilis. LPs and lipids were analyzed using GC-MS, LC-MS/MS and MALDI-TOF/TOF techniques. Compared with B. subtilis DSM 3257, membranes of the I'1a strain were characterized by an increased amount of anteiso fatty acids and a ten-fold higher ratio of phosphatidylglycerol (PG)-to-phosphatidylethanolamine (PE). Interestingly, in cultures of B. subtilis DSM 3257 supplemented with LP extracts of the I'1a strain, the PG-to-PE ratio was fourfold higher, and the amount of anteiso fatty acids was also increased.

The effect of bacteriocin-producing Lactobacillus plantarum strains on the intracellular pH of sessile and planktonic Listeria monocytongenes single cells

DEFF Research Database (Denmark)

Nielsen, Dennis Sandris; Cho, Gyu-Sung; Hanak, Alexander

2010-01-01

and/or bacteriocin-producing LAB as “natural” food preservatives in foods such as cheese, meat and ready-to-eat products. Some strains of Lactobacillus plantarum produce bacteriocins termed plantaricins. Using a single-cell based approach, the effect on the intracellular pH as a measure......A wide range of lactic acid bacteria (LAB) produce bacteriocins mainly active against other closely related LAB, but some bacteriocins are also active against the food-borne pathogen Listeria monocytogenes. With the aim of increasing food safety it has thus been considered to utilise bacteriocins...

Complete genome sequence of bacteriocin-producing Lactobacillus plantarum KLDS1.0391, a probiotic strain with gastrointestinal tract resistance and adhesion to the intestinal epithelial cells.

Science.gov (United States)

Jia, Fang-Fang; Zhang, Lu-Ji; Pang, Xue-Hui; Gu, Xin-Xi; Abdelazez, Amro; Liang, Yu; Sun, Si-Rui; Meng, Xiang-Chen

2017-10-01

Lactobacillus plantarum KLDS1.0391 is a probiotic strain isolated from the traditional fermented dairy products and identified to produce bacteriocin against Gram-positive and Gram-negative bacteria. Previous studies showed that the strain has a high resistance to gastrointestinal stress and has a high adhesion ability to the intestinal epithelial cells (Caco-2). We reported the entire genome sequence of this strain, which contains a circular 2,886,607-bp chromosome and three circular plasmids. Genes, which are related to the biosynthesis of bacteriocins, the stress resistance to gastrointestinal tract environment and adhesive performance, were identified. Whole genome sequence of Lactobacillus plantarum KLDS1.0391 will be helpful for its applications in food industry. Copyright © 2017 Elsevier Inc. All rights reserved.

Biosurfactant production from marine hydrocarbon-degrading consortia and pure bacterial strains using crude oil as carbon source.

Science.gov (United States)

Antoniou, Eleftheria; Fodelianakis, Stilianos; Korkakaki, Emmanouela; Kalogerakis, Nicolas

2015-01-01

Biosurfactants (BSs) are "green" amphiphilic molecules produced by microorganisms during biodegradation, increasing the bioavailability of organic pollutants. In this work, the BS production yield of marine hydrocarbon degraders isolated from Elefsina bay in Eastern Mediterranean Sea has been investigated. The drop collapse test was used as a preliminary screening test to confirm BS producing strains or mixed consortia. The community structure of the best consortia based on the drop collapse test was determined by 16S-rDNA pyrotag screening. Subsequently, the effect of incubation time, temperature, substrate and supplementation with inorganic nutrients, on BS production, was examined. Two types of BS - lipid mixtures were extracted from the culture broth; the low molecular weight BS Rhamnolipids and Sophorolipids. Crude extracts were purified by silica gel column chromatography and then identified by thin layer chromatography and Fourier transform infrared spectroscopy. Results indicate that BS production yield remains constant and low while it is independent of the total culture biomass, carbon source, and temperature. A constant BS concentration in a culture broth with continuous degradation of crude oil (CO) implies that the BS producing microbes generate no more than the required amount of BSs that enables biodegradation of the CO. Isolated pure strains were found to have higher specific production yields than the complex microbial marine community-consortia. The heavy oil fraction of CO has emerged as a promising substrate for BS production (by marine BS producers) with fewer impurities in the final product. Furthermore, a particular strain isolated from sediments, Paracoccus marcusii, may be an optimal choice for bioremediation purposes as its biomass remains trapped in the hydrocarbon phase, not suffering from potential dilution effects by sea currents.

Variation in the strain anisotropy of Zircaloy with temperature and strain

International Nuclear Information System (INIS)

Hindle, E.D.; Worswick, D.

1984-04-01

Strain anisotropy was investigated at temperatures in the range 293 to 1117K in circular tensile specimens prepared from rolled Zircaloy-2 plate so that their tensile axes were parallel to and transverse to the rolling direction. The strain anisotropy factor for both types of specimen increased markedly in the high alpha phase region above 923K reaching a maximum at circa 1070K. Above this temperature in the alpha-plus-beta phase region the strain anisotropy decreased rapidly as the proportion of beta phase increased and was almost non-existent at 1173K. The strain anisotropy was markedly strain dependent, particularly in the high alpha phase region. The study was extended to Zircaloy-4 pressurized water reactor (PWR) 17 x 17 type fuel rod tubing specimens which were strained under biaxial conditions using cooling conditions which promoted uniform diametral strain over most of their lengths (circa 250 mm). In these circumstances the strain anisotropy is manifest by a reduction in length. Measurement of this change along with that in diameter and wall thickness produced data from which the strain anisotropy factor was calculated. The results, although influenced by additional factors discussed in the paper, were similar to those observed in the uniaxial Zircaloy-2 tensile tests. (author)

Molecular analysis of yellow fever virus 17DD vaccine strain

Directory of Open Access Journals (Sweden)

Paulo R. Post

1991-06-01

Full Text Available The Oswaldo Cruz Foundation produces most of the yellow fever (YF vaccine prepared world wide. As part of a broader approach to determine the genetic variability in YF l7D seeds and vaccines and its relevance to viral attenuation the 17DD virus was purifed directly from chick embryo homogenates which is the source of virus used for vaccination of millions of people in Brazil and other countries for half a century. Neutralization and hemagglutination tests showed that the purified virus is similar to the original stock. Furthermore, radioimmune precipitation of 35S-methionine-labeled viral proteins using mouse hyperimmune ascitic fluid revealed identical patterns for the purified 17DD virus and the YF l7D-204 strain except for the 17DD E protein which migrated slower on SDS-PAGE. This difference is likely to be due to N-linked glycosylation. Finally, comparison by northern blot nybridization of virion RNAs of purified 17DD with two other strains of YF virus only fenome-sized molecules for all three viruses. These observations suggest that vaccine phenotype is primarily associated with the accumulation of mutations.

How different is the proteome of the extended spectrum β-lactamase producing Escherichia coli strains from seagulls of the Berlengas natural reserve of Portugal?

Science.gov (United States)

Monteiro, R; Hébraud, M; Chafsey, I; Poeta, P; Igrejas, G

2016-08-11

β-Lactam antibiotics like cefotaxime are the most commonly used antibacterial agents. Escherichia coli strains 5A, 10A, 12A and 23B isolated from Seagulls feces, are cefotaxime-resistant strains that produces extended-spectrum beta-lactamases. Bacterial resistance to these antibiotics occurs predominantly through structural modification on the penicillin-binding proteins and enzymatic inactivation by extended-spectrum β-lactamases. Using classical proteomic techniques (2D-GE) coupled to mass spectrometry and bioinformatics extended analysis, in this study, we report several significant differences in cytoplasmic proteins expression when the strains were submitted to antibiotic stress and when the resistant strains were compared with a non-resistant strain. A total of 79 differentially expressed spots were collected for protein identification. Significant level of expression was found in antibiotic resistant proteins like β-lactamase CTX-M-1 and TEM and also in proteins related with oxidative stress. This approach might help us understand which pathways form barriers for antibiotics, another possible new pathways involved in antibiotic resistance to devise appropriate strategies for their control already recognized by the World Health Organization and the European Commission. This study highlights the protein differences when a resistant strain is under antibiotic pressure and how different can be a sensible and resistant strain at the protein level. This survey might help us to understand the specifics barriers for antibiotics and which pathways are involved in its resistance crosswise the wildlife. Copyright © 2016 Elsevier B.V. All rights reserved.

Diversity of Micromonospora strains from the deep Mediterranean Sea and their potential to produce bioactive compounds

Directory of Open Access Journals (Sweden)

Andrea Gärtner

2016-06-01

Full Text Available During studies on bacteria from the Eastern Mediterranean deep-sea, incubation under in situ conditions (salinity, temperature and pressure and heat treatment were used to selectively enrich representatives of Micromonospora. From sediments of the Ierapetra Basin (4400 m depth and the Herodotos Plain (2800 m depth, 21 isolates were identified as members of the genus Micromonospora. According to phylogenetic analysis of 16S rRNA gene sequences, the Micromonospora isolates could be assigned to 14 different phylotypes with an exclusion limit of ≥ 99.5% sequence similarity. They formed 7 phylogenetic clusters. Two of these clusters, which contain isolates obtained after enrichment under pressure incubation and phylogenetically are distinct from representative reference organism, could represent bacteria specifically adapted to the conditions in situ and to life in these deep-sea sediments. The majority of the Micromonospora isolates (90% contained at least one gene cluster for biosynthesis of secondary metabolites for non-ribosomal polypeptides and polyketides (polyketide synthases type I and type II. The determination of biological activities of culture extracts revealed that almost half of the strains produced substances inhibitory to the growth of Gram-positive bacteria. Chemical analyses of culture extracts demonstrated the presence of different metabolite profiles also in closely related strains. Therefore, deep-sea Micromonospora isolates are considered to have a large potential for the production of new antibiotic compounds.

Isolation and characterization of new strains of cholesterol-reducing bacteria from baboons.

Science.gov (United States)

Brinkley, A W; Gottesman, A R; Mott, G E

1982-01-01

We isolated and characterized nine new strains of cholesterol-reducing bacteria from feces and intestinal contents of baboons. Cholesterol-brain agar was used for the primary isolation, and subsequent biochemical tests were done in a lecithin-cholesterol broth containing plasmenylethanolamine and various substrates. All strains had similar colony and cell morphology, hydrolyzed the beta-glucosides esculin and amygdalin, metabolized pyruvate, and produced acetate and acetoin. Unlike previously reported strains, the nine new strains did not require cholesterol and an alkenyl ether lipid (e.g., plasmalogen) for growth; however, only two strains reduced cholesterol in the absence of the plasmalogen. These two strains also produced succinate as an end product. Carbohydrate fermentation was variable; some strains produced weak acid (pH 5.5 to 6.0) from only a few carbohydrates, whereas other strains produced strong acid reactions (pH less than or equal to 5.5) from a wide variety of carbohydrates.

Improved production, purification, and characterization of biosurfactants produced by Serratia marcescens SM3 and its isogenic SMRG-5 strain.

Science.gov (United States)

Rosas-Galván, Nashbly Sarela; Martínez-Morales, Fernando; Marquina-Bahena, Silvia; Tinoco-Valencia, Raunel; Serrano-Carreón, Leobardo; Bertrand, Brandt; León-Rodríguez, Renato; Guzmán-Aparicio, Josefina; Alvaréz-Berber, Laura; Trejo-Hernández, María R

2018-02-19

In this study, the biosurfactants (Bs) production of two Serratia marcescens strains (SM3 and its isogenic SMRG-5 strain) was improved and the tenso-active agents were purified and characterized. A 2 3 factorial design was used to evaluate the effect of nitrogen and carbon sources on the surface tension (ST) reduction and emulsion index (EI 24 ) of the produced Bs. Optimum Bs production by SM3 was achieved at high concentrations of carbon and nitrogen, reducing ST to 26.5 ± 0.28 dynes/cm, with an EI 24 of 79.9 ± 0.2%. Meanwhile, the best results for SMRG-5 were obtained at low concentrations, reducing the ST to 25.2 ± 0.2 dynes/cm, with an EI 24 of 89.7 ± 0.28%. The optimal conditions for Bs production were scaled up in a 2-L reactor, yielding 4.8 and 5.2 g/L for SM3 and SMRG-5, respectively. Gas Chromatography-Mass Spectrometry (GC-MS) analysis revealed the presence of two different lipopeptides (hidrofobic fractions: octadecanoic and hexadecanoic acid for SM3 and SMRG5, respectively). Both strains were capable of benzo [a] pyrene removal (59% after 72 H of culture). © 2018 International Union of Biochemistry and Molecular Biology, Inc.

Mutation spectrum produced on PBR322 by 8-Methoxypsoralen plus UV-A light

International Nuclear Information System (INIS)

Bauluz, C.; Vidania, R.

1990-01-01

The mutagenic effect of 8-MOP+UVA (PUVA treatment) on pBR322 has been analysed by determining the frequency of mutation in the tet gene and identifying the type and position of the mutations produced inside a 276 pb-fragment (Bam-H1-SalI) of the same gene. pBR322 DNA was irradiated with UVA light in the presence of increasing concentrations of 8-Methoxypsoralen (8-MOP). The number of psoralen adducts formed in pBR322 upon that treatment ranged from 0 to 10.7 adducts per plasmid molecule. Modified DNA samples were used to transform several strains of E. Coli (differing in their repair capacities), both in constitutive conditions and after sos pre-induction by 254 nm-irradiation of cells. Mutation frequencies in the tet gene showed to increase in the wild type and uvrA strains along with the number of psoralen adducts per plasmid molecule; higher mutation frequencies were found in cells that had been previously irradiated to induce the SOS expression. Mutant plasmids were isolated from ApRTcS colonies and sequenced by the method of Maxam and Gilbert. Mutations appeared to be unique in most of the cases and were always punctual, i.e. affecting only to one base pair. The relative positions of the mutations showed a high frequency of coincidence among the sequenced fragments, indicating the existence of several DNA regions with high probability to mutated ('hot spots'). (author)

Comparative evaluation of extracellular β-D-fructofuranosidase in submerged and solid-state fermentation produced by newly identified Bacillus subtilis strain.

Science.gov (United States)

Lincoln, Lynette; More, Sunil S

2018-04-17

To screen and identify a potential extracellular β-D-fructofuranosidase or invertase producing bacterium from soil, and comparatively evaluate the enzyme biosynthesis under submerged and solid-state fermentation. Extracellular invertase producing bacteria were screened from soil. Identification of the potent bacterium was performed based on microscopic examinations and 16S rDNA molecular sequencing. Bacillus subtilis LYN12 invertase secretion was surplus with wheat bran humidified with molasses medium (70%), with elevated activity at 48 h and 37 °C under solid-state fermentation, whereas under submerged conditions increased activity was observed at 24 h and 45 °C in the molasses medium. The study revealed a simple fermentative medium for elevated production of extracellular invertase from a fast growing Bacillus strain. Bacterial invertases are scarce and limited reports are available. By far, this is the first report on the comparative analysis of optimization of extracellular invertase synthesis from Bacillus subtilis strain by submerged and solid-state fermentation. The use of agricultural residues increased yields resulting in development of a cost-effective and stable approach. Bacillus subtilis LYN12 invertase possesses excellent fermenting capability to utilize agro-industrial residues under submerged and solid-state conditions. This could be a beneficial candidate in food and beverage processing industries. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Profile of Shiga toxin-producing Escherichia coli strains isolated from dogs and cats and genetic relationships with isolates from cattle, meat and humans.

Science.gov (United States)

Bentancor, A; Rumi, M V; Carbonari, C; Gerhardt, E; Larzábal, M; Vilte, D A; Pistone-Creydt, V; Chinen, I; Ibarra, C; Cataldi, A; Mercado, E C

2012-05-04

Pets can be reservoirs of Shiga toxin-producing Escherichia coli (STEC) strains. The aim of this study was to examine nine strains belonging to several serotypes (O91:H21, O91:H16, O178:H19, O8:H19, O22:H8, O22:HNT, ONT:H8), previously recovered from cats or dogs. To this end, we assessed a set of additional virulence genes (stx(2) subtype, subAB, ehxA, eae and saa), cytotoxic activity, and genetic relationships with strains isolated from cattle, meat and humans using pulsed-field gel electrophoresis (PFGE). Most of the isolates carried the stx(2) and/or stx(2vh-b) sequences, while only the O91:H21 isolate presented the mucus-activatable stx(2d) variant, as confirmed by sequencing the genes of subunits A and B. All the strains showed cytotoxic activity in cultured cells. One of the two O178:H19, selected for its high level of cytotoxicity in Vero cells, showed the ability to cause functional alterations in the human colon mucosa in vitro. None of the strains possessed the subAB, eae or saa genes and only the strains belonging to serotype O8:H19 carried the ehxA gene. The isolates shared 90-100% similarity by PFGE to epidemiologically unrelated strains of the corresponding serotypes recovered from cattle, meat or humans. Our results demonstrate that dogs and cats may have a role in the infection of humans by STEC, probably serving as a vehicle for bovine strains in the cycle of human infection, and thus emphasize the health risks for owners and their families. Copyright © 2011 Elsevier B.V. All rights reserved.

Purification and characterization of ribosomal proteins L27 and L30 having antimicrobial activity produced by the Lactobacillus salivarius SGL 03.

Science.gov (United States)

Pidutti, P; Federici, F; Brandi, J; Manna, L; Rizzi, E; Marini, U; Cecconi, D

2018-02-01

The aim of this study was to investigate the antimicrobial potential of proteins secreted by a new strain of Lactobacillus salivarius. The secretome of L. salivarius SGL 03 strain was analysed by gel-assisted fractionation and MS/MS to identify low-molecular-mass proteins. This strategy allowed us to identify 10 secreted proteins. Then, a combination of heterologous expression and agar well diffusion was used to characterize them as to their antimicrobial activity, mechanisms of action and stability. Our findings indicate that L27 and L30 proteins of the 50S ribosomal subunit have antimicrobial activity against Streptococcus pyogenes, Streptococcus uberis and Enterococcus faecium. In addition, both proteins are bactericidal against S. pyogenes and maintain their antimicrobial activity after different protease treatments, at acidic pH, after heat treatment, and if stored in a refrigerated ambient at least at 4°C. The overall results demonstrated that the L27 and L30 ribosomal proteins are of interest as new antimicrobial molecules to prevent the growth of S. pyogenes, S. uberis and E. faecium. Our results provide the first insight into the extra-ribosomal activity of L27 and L30 secreted proteins of L. salivarius. This study demonstrated the capacity of L. salivarius SGL 03 to produce antimicrobial molecules and suggested this strain as a promising probiotic candidate. © 2017 The Society for Applied Microbiology.

Effect of gamma radiation on the reduction of Salmonella strains, Listeria monocytogenes, and Shiga toxin-producing Escherichia coli and sensory evaluation of minimally processed spinach (Tetragonia expansa).

Science.gov (United States)

Rezende, Ana Carolina B; Igarashi, Maria Crystina; Destro, Maria Teresa; Franco, Bernadette D G M; Landgraf, Mariza

2014-10-01

This study evaluated the effects of irradiation on the reduction of Shiga toxin-producing Escherichia coli (STEC), Salmonella strains, and Listeria monocytogenes, as well as on the sensory characteristics of minimally processed spinach. Spinach samples were inoculated with a cocktail of three strains each of STEC, Salmonella strains, and L. monocytogenes, separately, and were exposed to gamma radiation doses of 0, 0.2, 0.4, 0.6, 0.8, and 1.0 kGy. Samples that were exposed to 0.0, 1.0, and 1.5 kGy and kept under refrigeration (4°C) for 12 days were submitted to sensory analysis. D10 -values ranged from 0.19 to 0.20 kGy for Salmonella and from 0.20 to 0.21 for L. monocytogenes; for STEC, the value was 0.17 kGy. Spinach showed good acceptability, even after exposure to 1.5 kGy. Because gamma radiation reduced the selected pathogens without causing significant changes in the quality of spinach leaves, it may be a useful method to improve safety in the fresh produce industry.

Aligning molecules with intense nonresonant laser fields

DEFF Research Database (Denmark)

Larsen, J.J.; Safvan, C.P.; Sakai, H.

1999-01-01

Molecules in a seeded supersonic beam are aligned by the interaction between an intense nonresonant linearly polarized laser field and the molecular polarizability. We demonstrate the general applicability of the scheme by aligning I2, ICl, CS2, CH3I, and C6H5I molecules. The alignment is probed...... by mass selective two dimensional imaging of the photofragment ions produced by femtosecond laser pulses. Calculations on the degree of alignment of I2 are in good agreement with the experiments. We discuss some future applications of laser aligned molecules....

Continuous centrifuge decelerator for polar molecules.

Science.gov (United States)

Chervenkov, S; Wu, X; Bayerl, J; Rohlfes, A; Gantner, T; Zeppenfeld, M; Rempe, G

2014-01-10

Producing large samples of slow molecules from thermal-velocity ensembles is a formidable challenge. Here we employ a centrifugal force to produce a continuous molecular beam with a high flux at near-zero velocities. We demonstrate deceleration of three electrically guided molecular species, CH3F, CF3H, and CF3CCH, with input velocities of up to 200  m s(-1) to obtain beams with velocities below 15  m s(-1) and intensities of several 10(9)  mm(-2) s(-1). The centrifuge decelerator is easy to operate and can, in principle, slow down any guidable particle. It has the potential to become a standard technique for continuous deceleration of molecules.

Fleming's penicillin producing streain is not Penicillium chrysogenum but P. rubens

DEFF Research Database (Denmark)

Houbraken, Jos; Frisvad, Jens Christian; Samson, Robert A.

2011-01-01

Penicillium chrysogenum is a commonly occurring mould in indoor environments and foods, and has gained much attention for its use in the production of the antibiotic penicillin. Phylogenetic analysis of the most important penicillin producing P. chrysogenum isolates revealed the presence of two...... not produce these metabolites. Fleming’s original penicillin producing strain and the full genome sequenced strain of P. chrysogenum are re-identified as P. rubens. Furthermore, the well-known claim that Alexander Fleming misidentified the original penicillin producing strain as P. rubrum is discussed....

[An Efficient Method for Genetic Certification of Bacillus subtilis strains, Prospective Producers of Biopreparations].

Science.gov (United States)

Terletskiy, V P; Tyshenko, V I; Novikova, I I; Boikova, I V; Tyulebaev, S D; Shakhtamirov, I Ya

2016-01-01

Genetic certification of commercial strains of bacteria antagonistic to phytopathogenic microorganisms guarantees their unequivocal identification and confirmation of safety. In Russia, unlike EU countries, genetic certification of Bacillus subtilis strains is not used. Based on the previously proposed double digestion selective label (DDSL) fingerprinting, a method for genetic identification and certification of B. subtilis strains was proposed. The method was tested on several strains differing in their physiological and biochemical properties and in the composition of secondary metabolites responsible for the spectrum of antibiotic activity. High resolving power of this approach was shown. Optimal restriction endonucleases (SgsI and Eco32I) were determined and validated. A detailed protocol for genetic certification of this bacterial species was developed. DDSL is a universal method, which may be adapted for genetic identification and certification of other bacterial species.

A new regulatory mechanism controlling carotenogenesis in the fungus Mucor circinelloides as a target to generate β-carotene over-producing strains by genetic engineering.

Science.gov (United States)

Zhang, Yingtong; Navarro, Eusebio; Cánovas-Márquez, José T; Almagro, Lorena; Chen, Haiqin; Chen, Yong Q; Zhang, Hao; Torres-Martínez, Santiago; Chen, Wei; Garre, Victoriano

2016-06-07

Carotenoids are natural pigments with antioxidant properties that have important functions in human physiology and must be supplied through the diet. They also have important industrial applications as food colourants, animal feed additives and nutraceuticals. Some of them, such as β-carotene, are produced on an industrial scale with the use of microorganisms, including fungi. The mucoral Blakeslea trispora is used by the industry to produce β-carotene, although optimisation of production by molecular genetic engineering is unfeasible. However, the phylogenetically closely related Mucor circinelloides, which is also able to accumulate β-carotene, possesses a vast collection of genetic tools with which to manipulate its genome. This work combines classical forward and modern reverse genetic techniques to deepen the regulation of carotenoid synthesis and generate candidate strains for biotechnological production of β-carotene. Mutagenesis followed by screening for mutants with altered colour in the dark and/or in light led to the isolation of 26 mutants that, together with eight previously isolated mutants, have been analysed in this work. Although most of the mutants harboured mutations in known structural and regulatory carotenogenic genes, eight of them lacked mutations in those genes. Whole-genome sequencing of six of these strains revealed the presence of many mutations throughout their genomes, which makes identification of the mutation that produced the phenotype difficult. However, deletion of the crgA gene, a well-known repressor of carotenoid biosynthesis in M. circinelloides, in two mutants (MU206 and MU218) with high levels of β-carotene resulted in a further increase in β-carotene content to differing extents with respect to the crgA single-null strain; in particular, one strain derived from MU218 was able to accumulate up to 4 mg/g of β-carotene. The additive effect of crgA deletion and the mutations present in MU218 suggests the existence of a

Effect of biosurfactant from two strains of Pseudomonas on ...

African Journals Online (AJOL)

Two Pseudomonas strains isolated from oil-contaminated soil which produce biosurfactant were studied. The biosurfactant containing broth formed stable emulsions with liquid light paraffin, cooking medium vegetable oil and toluene. The strains under study produce extra cellular biosurfactant in the culture media.

Analysis of the genomic sequences and metabolites of Serratia surfactantfaciens sp. nov. YD25T that simultaneously produces prodigiosin and serrawettin W2.

Science.gov (United States)

Su, Chun; Xiang, Zhaoju; Liu, Yibo; Zhao, Xinqing; Sun, Yan; Li, Zhi; Li, Lijun; Chang, Fan; Chen, Tianjun; Wen, Xinrong; Zhou, Yidan; Zhao, Furong

2016-11-03

Gram-negative bacteria of the genus Serratia are potential producers of many useful secondary metabolites, such as prodigiosin and serrawettins, which have potential applications in environmental bioremediation or in the pharmaceutical industry. Several Serratia strains produce prodigiosin and serrawettin W1 as the main bioactive compounds, and the biosynthetic pathways are co-regulated by quorum sensing (QS). In contrast, the Serratia strain, which can simultaneously produce prodigiosin and serrawettin W2, has not been reported. This study focused on analyzing the genomic sequence of Serratia sp. strain YD25 T isolated from rhizosphere soil under continuously planted burley tobacco collected from Yongding, Fujian province, China, which is unique in producing both prodigiosin and serrawettin W2. A hybrid polyketide synthases (PKS)-non-ribosomal peptide synthetases (NRPS) gene cluster putatively involved in biosynthesis of antimicrobial serrawettin W2 was identified in the genome of YD25 T , and its biosynthesis pathway was proposed. We found potent antimicrobial activity of serrawettin W2 purified from YD25 T against various pathogenic bacteria and fungi as well as antitumor activity against Hela cells. Subsequently, comparative genomic analyses were performed among a total of 133 Serratia species. The prodigiosin biosynthesis gene cluster in YD25 T belongs to the type I pig cluster, which is the main form of pig-encoding genes existing in most of the pigmented Serratia species. In addition, a complete autoinducer-2 (AI-2) system (including luxS, lsrBACDEF, lsrGK, and lsrR) as a conserved bacterial operator is found in the genome of Serratia sp. strain YD25 T . Phylogenetic analysis based on concatenated Lsr and LuxS proteins revealed that YD25 T formed an independent branch and was clearly distant from the strains that solely produce either prodigiosin or serrawettin W2. The Fe (III) ion reduction assay confirmed that strain YD25 T could produce an AI-2 signal

Enhancing the humidity sensitivity of Ga2O3 /SnO2 core/shell microribbon by applying mechanical strain and its application as a flexible strain sensor.

Science.gov (United States)

Liu, Kewei; Sakurai, Makoto; Aono, Masakazu

2012-12-07

The humidity sensitivity of a single β-Ga(2) O(3) /amorphous SnO(2) core/shell microribbon on a flexible substrate is enhanced by the application of tensile strain and increases linearly with the strain. The strain-induced enhancement originates from the increase in the effective surface area where water molecules are adsorbed. This strain dependence of humidity sensitivity can be used to monitor the external strain. The strain sensing of the microribbon device under various amounts of mechanical loading shows excellent reliability and reproducibility with a gauge factor of -41. The flexible device has high potential to detect both humidity and strain at room temperature. These findings and the mechanism involved are expected to pave the way for new flexible strain and multifunctional sensors. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Discovery of novel small molecule modulators of Clavibacter michiganensis subsp. michiganensis

Directory of Open Access Journals (Sweden)

Xiulan eXu

2015-10-01

Full Text Available Clavibacter michiganensis subsp. michiganensis (Cmm is a Gram-positive seed-transmitted bacterial phytopathogen responsible for substantial economic losses by adversely affecting tomato production worldwide. A high-throughput, cell-based screen was adapted to identify novel small molecule growth inhibitors to serve as leads for future bactericide development. A library of 4,182 compounds known to be bioactive against Saccharomyces cerevisiae was selected for primary screening against Cmm wild-type strain C290 for whole-cell growth inhibition. Four hundred sixty-eight molecules (11.2% hit rate were identified as bacteriocidal or bacteriostatic against Cmm at 200 M. Seventy-seven candidates were selected based on Golden Triangle analyses for secondary screening. Secondary screens showed that several of these candidates were strain-selective. Several compounds were inhibitory to multiple Cmm strains as well as Bacillus subtilis, but not Pseudomonas fluorescens, Mitsuaria sp., Lysobacter enzymogenes, Lactobacillus rhamnosus, Bifidobacter animalis, or Escherichia coli. Most of the compounds were not phytotoxic and did not show overt host toxicity. Using a novel 96-well bioluminescent Cmm seedling infection assay, we assessed effects of selected compounds on pathogen infection. The 12 most potent novel molecules were identified by compiling the scores from all secondary screens combined with the reduction of pathogen infection in planta. When tested for ability to develop resistance to the top-12 compounds, no resistant Cmm were recovered, suggesting that the discovered compounds are unlikely to induce resistance. In conclusion, here we report top-12 compounds that provide chemical scaffolds for future Cmm-specific bactericide development.

Abrupt relaxation in high-spin molecules

International Nuclear Information System (INIS)

Chang, C.-R.; Cheng, T.C.

2000-01-01

Mean-field model suggests that the rate of resonant quantum tunneling in high-spin molecules is not only field-dependent but also time-dependent. The relaxation-assisted resonant tunneling in high-spin molecules produces an abrupt magnetization change during relaxation. When the applied field is very close to the resonant field, a time-dependent interaction field gradually shifts the energies of different collective spin states, and magnetization tunneling is observed as two energies of the spin states coincide

Comparative Genomics of Acetobacterpasteurianus Ab3, an Acetic Acid Producing Strain Isolated from Chinese Traditional Rice Vinegar Meiguichu.

Science.gov (United States)

Xia, Kai; Li, Yudong; Sun, Jing; Liang, Xinle

2016-01-01

Acetobacter pasteurianus, an acetic acid resistant bacterium belonging to alpha-proteobacteria, has been widely used to produce vinegar in the food industry. To understand the mechanism of its high tolerance to acetic acid and robust ability of oxidizing ethanol to acetic acid (> 12%, w/v), we described the 3.1 Mb complete genome sequence (including 0.28 M plasmid sequence) with a G+C content of 52.4% of A. pasteurianus Ab3, which was isolated from the traditional Chinese rice vinegar (Meiguichu) fermentation process. Automatic annotation of the complete genome revealed 2,786 protein-coding genes and 73 RNA genes. The comparative genome analysis among A. pasteurianus strains revealed that A. pasteurianus Ab3 possesses many unique genes potentially involved in acetic acid resistance mechanisms. In particular, two-component systems or toxin-antitoxin systems may be the signal pathway and modulatory network in A. pasteurianus to cope with acid stress. In addition, the large numbers of unique transport systems may also be related to its acid resistance capacity and cell fitness. Our results provide new clues to understanding the underlying mechanisms of acetic acid resistance in Acetobacter species and guiding industrial strain breeding for vinegar fermentation processes.

Mesophilic Lactic Acid Bacteria Diversity Encountered in Brazilian Farms Producing Milk with Particular Interest in Lactococcus lactis Strains.

Science.gov (United States)

Luiz, L M P; Chuat, V; Madec, M N; Araújo, E A; de Carvalho, A F; Valence, F

2016-10-01

The milk produced in regions with different traditions in Brazil is used for artisanal product production, which is characterized by different sensorial characteristics. This study aimed to identify the bacterial ecosystem of farms located in a traditional dairy region in the state of Minas Gerais and to characterize Lactococcus lactis strains, the species of interest in this study, using a multilocus sequence typing (MLST) protocol and pulsed-field gel electrophoresis (PFGE) technique. Samples were collected from raw milk and dairy environment from six farms. A total of 50 isolates were analyzed using 16S rRNA sequencing and species-specific PCR. Five genera were identified: Lactobacillus, Leuconostoc, Lactococcus, Enterococcus, and Staphylococcus, from ten different species. MLST (with six housekeeping genes) and PFGE (with SmaI endonuclease) were used for the characterization of 20 isolates of Lactococcus lactis from a dairy collection in this study. Both methods revealed a high clonal diversity of strains with a higher discriminatory level for PFGE (15 pulsotypes), compared to MLST (12 ST). This study contributes to the preservation of the Brazilian dairy heritage and provides insights into a part of the LAB population found in raw milk and dairy environment.

Cyanobacteria as efficient producers of mycosporine-like amino acids.

Science.gov (United States)

Jain, Shikha; Prajapat, Ganshyam; Abrar, Mustari; Ledwani, Lalita; Singh, Anoop; Agrawal, Akhil

2017-09-01

Mycosporine-like amino acids are the most common group of transparent ultraviolet radiation absorbing intracellular secondary metabolites. These molecules absorb light in the range of ultraviolet-A and -B with a maximum absorbance between 310 and 362 nm. Cyanobacteria might have faced the most deleterious ultraviolet radiation, which leads to an evolution of ultraviolet protecting mycosporine-like amino acids for efficient selection in the environment. In the last 30 years, scientists have investigated various cyanobacteria for novel mycosporine-like amino acids, applying different induction techniques. This review organizes all the cyanobacterial groups that produce various mycosporine-like amino acids. We found out that cyanobacteria belonging to orders Synechococcales, Chroococcales, Oscillatoriales, and Nostocales are frequently studied for the presence of mycosporine-like amino acids, while orders Gloeobacterales, Spirulinales, Pleurocapsales, and Chroococcidiopsidales are still need to be investigated. Nostoc and Anabaena strains are major studied genus for the mycosporine-like amino acids production. Hence, this review will give further insight to the readers about potential mycosporine-like amino acid producing cyanobacterial groups in future investigations. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Substitution Structures of Large Molecules and Medium Range Correlations in Quantum Chemistry Calculations

Science.gov (United States)

Evangelisti, Luca; Pate, Brooks

2017-06-01

A study of the minimally exciting topic of agreement between experimental and measured rotational constants of molecules was performed on a set of large molecules with 16-18 heavy atoms (carbon and oxygen). The molecules are: nootkatone (C_{15}H_{22}O), cedrol (C_{15}H_{26}O), ambroxide (C_{16}H_{28}O), sclareolide (C_{16}H_{22}O_{2}), and dihydroartemisinic acid (C_{15}H_{24}O_{2}). For this set of molecules we obtained 13C-subsitution structures for six molecules (this includes two conformers of nootkatone). A comparison of theoretical structures and experimental substitution structures was performed in the spirit of the recent work of Grimme and Steinmetz.[1] Our analysis focused the center-of-mass distance of the carbon atoms in the molecules. Four different computational methods were studied: standard DFT (B3LYP), dispersion corrected DFT (B3LYP-D3BJ), hybrid DFT with dispersion correction (B2PLYP-D3), and MP2. A significant difference in these theories is how they handle medium range correlation of electrons that produce dispersion forces. For larger molecules, these dispersion forces produce an overall contraction of the molecule around the center-of-mass. DFT poorly treats this effect and produces structures that are too expanded. MP2 calculations overestimate the correction and produce structures that are too compact. Both dispersion corrected DFT methods produce structures in excellent agreement with experiment. The analysis shows that the difference in computational methods can be described by a linear error in the center-of-mass distance. This makes it possible to correct poorer performing calculations with a single scale factor. We also reexamine the issue of the "Costain error" in substitution structures and show that it is significantly larger in these systems than in the smaller molecules used by Costain to establish the error limits. [1] Stefan Grimme and Marc Steinmetz, "Effects of London dispersion correction in density functional theory on

A new methodology to obtain wine yeast strains overproducing mannoproteins.

Science.gov (United States)

Quirós, Manuel; Gonzalez-Ramos, Daniel; Tabera, Laura; Gonzalez, Ramon

2010-04-30

Yeast mannoproteins are highly glycosylated proteins that are covalently bound to the beta-1,3-glucan present in the yeast cell wall. Among their outstanding enological properties, yeast mannoproteins contribute to several aspects of wine quality by protecting against protein haze, reducing astringency, retaining aroma compounds and stimulating growth of lactic-acid bacteria. The development of a non-recombinant method to obtain enological yeast strains overproducing mannoproteins would therefore be very useful. Our previous experience on the genetic determinants of the release of these molecules by Saccharomyces cerevisiae has allowed us to propose a new methodology to isolate and characterize wine yeast that overproduce mannoproteins. The described methodology is based on the resistance of the killer 9 toxin produced by Williopsis saturnus, a feature linked to an altered biogenesis of the yeast cell wall. Copyright 2010 Elsevier B.V. All rights reserved.

A new strain of Claviceps purpurea accumulating tetracyclic clavine alkaloids.

Science.gov (United States)

Schumann, B; Erge, D; Maier, W; Gröger, D

1982-05-01

A new strain of Claviceps was isolated from a blokked mutant of Claviceps purpurea. This strain accumulates substantial amounts of clavine alkaloids (2 g/l). The alkaloid fraction is composed of chanoclavine-I ( approximately 10%) and a mixture of agroclavine/elymoclavine (90%). Most suitable for alkaloid production in submerged culture is an ammoncitrate/sucrose medium. The genealogy of the new strain, designated Pepty 695/ch-I is the following one: Pepty 695/S (ergotoxine producer) --> Pepty 695/ch (secoergoline producer) --> Pepty 695/ch-I (tetracyclic clavine producer).

Influence of the water molecules near surface of viral protein on virus activation process

Energy Technology Data Exchange (ETDEWEB)

O, Shepelenko S; S, Salnikov A; V, Rak S; P, Goncharova E; B, Ryzhikov A, E-mail: shep@vector.nsc.r, E-mail: shep@ngs.r [Federal State Research Institution State Research Center of Virology and Biotechnology VECTOR of the Federal Service for Surveillance in Consumer Rights Protection and Human Well-being (FSRI SRC VB VECTOR) Koltsovo, Novosibirsk Region (Russian Federation)

2009-06-01

The infection of a cell with influenza virus comprises the stages of receptor binding to the cell membrane, endocytosis of virus particle, and fusion of the virus envelope and cell endosome membrane, which is determined by the conformational changes in hemagglutinin, a virus envelope protein, caused by pH decrease within the endosome. The pH value that induces conformation rearrangements of hemagglutinin molecule considerably varies for different influenza virus strains, first and foremost, due to the differences in amino acid structure of the corresponding proteins. The main goal of this study was to construct a model making it possible to assess the critical pH value characterizing the fusogenic activity of influenza virus hemagglutinin from the data on hemagglutinin structure and experimental verification of this model. Under this model, we assume that when the electrostatic force between interacting hemagglutinin molecules in the virus envelop exceeds a certain value, the hemagglutinin HA1 subunits are arranged so that they form a cavity sufficient for penetration of water molecules. This event leads to an irreversible hydration of the inner fragments of hemagglutinin molecule in a trimer and to the completion of conformational changes. The geometry of electrostatic field in hemagglutinin trimer was calculated taking into account the polarization effects near the interface of two dielectrics, aqueous medium and protein macromolecule. The critical pH values for the conformational changes in hemagglutinin were measured by the erythrocyte hemolysis induced by influenza virus particles when decreasing pH. The critical pH value conditionally separating the pH range into the regions with and without the conformational changes was calculated for several influenza virus H1N1 and H3N2 strains based on the data on the amino acid structure of the corresponding hemagglutinin molecules. Comparison of the theoretical and experimental values of critical pH values for

How strained are carbomeric-cycloalkanes?

Science.gov (United States)

Wodrich, Matthew D; Gonthier, Jérôme F; Steinmann, Stephan N; Corminboeuf, Clémence

2010-06-24

The ring strain energies of carbomeric-cycloalkanes (molecules with one or more acetylene spacer units placed into carbon single bonds) are assessed using a series of isodesmic, homodesmotic, and hyperhomodesmotic chemical equations. Isodesmic bond separation reactions and other equations derived from the explicitly defined hierarchy of homodesmotic equations are insufficient for accurately determining these values, since not all perturbing effects (i.e., conjugation and hyperconjugation) are fully balanced. A set of homodesmotic reactions is proposed, which succeeds in balancing all stereoelectronic effects present within the carbomeric rings, allowing for a direct assessment of the strain energies. Values calculated from chemical equations are validated using an increment/additivity approach. The ring strain energy decreases as acetylene units are added, manifesting from the net stabilization gained by opening the C-CH(2)-C angle around the methylene groups and the destabilization arising from bending the C-C identical withC angles of the spacer groups. This destabilization vanishes with increasing parent ring size (i.e., the angle distortion is less in the carbomeric-cyclobutanes than in the carbomeric-cyclopropanes), leading to strain energies near zero for carbo(n)-cyclopentanes and carbo(n)-cyclohexanes.

FIRST REPORT OF METALLO-β-LACTAMASES PRODUCING Enterobacter spp. STRAINS FROM VENEZUELA

Science.gov (United States)

Martínez, Dianny; Rodulfo, Hectorina E.; Rodríguez, Lucy; Caña, Luisa E.; Medina, Belkis; Guzman, Militza; Carreño, Numirin; Marcano, Daniel; Donato, Marcos De

2014-01-01

Clinical strains of Enterobacter were isolated from Cumana's Central Hospital in Venezuela, and classified as E. cloacae (21), E. aerogenes (7), E. intermedium (1), E. sakazakii (1) and three unclassified. The strains showed high levels of resistance, especially to SXT (58.1%), CRO (48.8%), CAZ (46.6%), PIP (46.4%), CIP (45.2%) and ATM (43.3%). This is the first report for South America of bla VIM-2 in two E. cloacae and one Enterobacter sp., which also showed multiple mechanisms of resistance. Both E. cloacae showed bla TEM-1, but only one showed bla CTX-M-15 gene, while no bla SHV was detected. PMID:24553611

Mechanochemical Association Reaction of Interfacial Molecules Driven by Shear.

Science.gov (United States)

Khajeh, Arash; He, Xin; Yeon, Jejoon; Kim, Seong H; Martini, Ashlie

2018-05-29

Shear-driven chemical reaction mechanisms are poorly understood because the relevant reactions are often hidden between two solid surfaces moving in relative motion. Here, this phenomenon is explored by characterizing shear-induced polymerization reactions that occur during vapor phase lubrication of α-pinene between sliding hydroxylated and dehydroxylated silica surfaces, complemented by reactive molecular dynamics simulations. The results suggest that oxidative chemisorption of the α-pinene molecules at reactive surface sites, which transfers oxygen atoms from the surface to the adsorbate molecule, is the critical activation step. Such activation takes place more readily on the dehydroxylated surface. During this activation, the most strained part of the α-pinene molecules undergoes a partial distortion from its equilibrium geometry, which appears to be related to the critical activation volume for mechanical activation. Once α-pinene molecules are activated, association reactions occur between the newly attached oxygen and one of the carbon atoms in another molecule, forming ether bonds. These findings have general implications for mechanochemistry because they reveal that shear-driven reactions may occur through reaction pathways very different from their thermally induced counterparts and specifically the critical role of molecular distortion in such reactions.

Collision data involving hydro-carbon molecules

International Nuclear Information System (INIS)

Tawara, H.; Itikawa, Y.; Nishimura, H.; Tanaka, H.; Nakamura, Y.

1990-07-01

Hydro-carbon molecules are abundantly produced when graphites are used as internal wall materials of hydrogen plasmas and strongly influence properties of low temperature plasmas near the edges as well as those of high temperature plasmas at the center. In this report, following simple description of the production mechanisms of hydro-carbon molecules under the interactions between graphite and hydrogen plasma, the present status of collision data for hydro-carbon molecules by electron impact is discussed and the relevant data are summarized in a series of figures and tables. It should also be noted that, in addition to fusion plasmas, these hydrocarbon data compiled here are quite useful in other applications such as plasma chemistry and material processing. (author)

Characterization of Emetic Bacillus weihenstephanensis, a New Cereulide-Producing Bacterium

DEFF Research Database (Denmark)

Thorsen, Line; Munk Hansen, Bjarne; Nielsen, Kristian Fog

2006-01-01

Cereulide production has until now been restricted to the species Bacillus cereus. Here we report on two psychrotolerant Bacillus weihenstephanensis strains, MC67 and MC118, that produce cereulide. The strains are atypical with regard to pheno- and genotypic characteristics normally used for iden......Cereulide production has until now been restricted to the species Bacillus cereus. Here we report on two psychrotolerant Bacillus weihenstephanensis strains, MC67 and MC118, that produce cereulide. The strains are atypical with regard to pheno- and genotypic characteristics normally used...

Biosynthesis, purification and characterization of endoglucanase from a xylanase producing strain Aspergillus niger B03

Directory of Open Access Journals (Sweden)

Georgi Todorov Dobrev

2012-03-01

Full Text Available An extracellular endoglucanase was isolated from the culture liquid of xylanase producing strain Aspergillus niger B03. The enzyme was purified to a homogenous form, using consecutive ultrafiltration, anion exchange chromatography, and gel filtration. Endoglucanase was a monomer protein with a molecular weight of 26,900 Da determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and 28,800 Da determined by gel filtration. The optimal pH and temperature values for the enzyme action were 3.5 and 65ºC respectively. Endoglucanase was stable at 40ºC, pH 3.0 for 210 min. The substrate specificity of the enzyme was determined with carboxymethyl cellulose, filter paper, and different glycosides. Endoglucanase displayed maximum activity in the case of carboxymethyl cellulose, with a Km value of 21.01 mg/mL. The substrate specificity and the pattern of substrate degradation suggested that the enzyme is an endoglucanase. Endoglucanase showed a synergism with endoxylanase in corn cobs hydrolysis.

Complete genome sequence of Lactobacillus plantarum LZ95, a potential probiotic strain producing bacteriocins and B-group vitamin riboflavin.

Science.gov (United States)

Li, Ping; Gu, Qing

2016-07-10

Lactobacillus plantarum LZ95 is a potential probiotic isolated from newborn infant fecal and it is identified to produce riboflavin with great antimicrobial activity. The complete genome sequence of this strain was reported in the present study. The genome contains a 3,261,418-bp chromosome and two plasmids. Genes, related to the biosynthesis of bacteriocins and riboflavin, were identified. This work will facilitate to reveal the biosynthetic mechanism of bacteriocins and B-group vitamins in lactic acid bacteria and provide evidence for its potential application in food industry. Copyright © 2016 Elsevier B.V. All rights reserved.

Molecules decreasing the amount of wastes

International Nuclear Information System (INIS)

Grumberg, P.

1993-01-01

This popularization paper reviews the separation of actinides from radioactive wastes by molecules such as crown ethers to reduce storage and the use of amides instead of TBP to reduce secondary wastes produced by combustion

Mycotoxin producing potential of some isolates of Aspergillus flavus and Eurotium groups from meat products.

Science.gov (United States)

el-Kady, I; el-Maraghy, S; Zohri, A N

1994-09-01

All strains (92) of A. flavus group proved to be positive for production of aflatoxin (45 to 1200 micrograms/50 ml medium) on potato dextrose liquid medium, while 59 strains only proved to be positive (35-310 micrograms/50 ml) on 15% NaCl potato-dextrose liquid medium. Most of the strains tested of A. flavus, A. flavus var. columnaris and A. oryzae produced aflatoxins B1, B2, G1 & G2. All positive strains of A. tamarii produced aflatoxins G1 & G2 while the tested isolate of A. zonatus produced aflatoxins B1 & G1. Of 95 strains tested of Eurotium, aflatoxins B1 & G1 were produced by one strain of each of E. chevalieri var. intermedium, E. repens and E. rubrum. Gliotoxin was detected in the extract of two strains of E. chevalieri and one strain of each of E. chevalieri var. intermedium and E. pseudoglaucum on the salt-free medium, and two strains of each of E. chevalieri, E. chevalieri var. intermedium and one of E. pseudoglaucum on 15% NaCl medium. Sterigmatocystin was produced by some strains of E. chevalieri, E. chevalieri var. intermedium, E. amstelodami, E. pseudoglaucum and E. rubrum on the two experimental media. One strain only of E. repens produced ochratoxin A while citrinin was detected in the extract of one strain of E. pseudoglaucum.

Biosurfactant production from marine hydrocarbon-degrading consortia and pure bacterial strains using crude oil as carbon source

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Eleftheria eAntoniou

2015-04-01

Full Text Available Biosurfactants (BS are green amphiphilic molecules produced by microorganisms during biodegradation, increasing the bioavailability of organic pollutants. In this work, the BS production yield of marine hydrocarbon degraders isolated from Elefsina bay in Eastern Mediterranean Sea has been investigated. The drop collapse test was used as a preliminary screening test to confirm biosurfactant producing strains or mixed consortia. The community structure of the best consortia based on the drop collapse test was determined by 16S-rDNA pyrotag screening. Subsequently, the effect of incubation time, temperature, substrate and supplementation with inorganic nutrients, on biosurfactant production, was examined. Two types of BS - lipid mixtures were extracted from the culture broth; the low molecular weight BS Rhamnolipids and Sophorolipids. Crude extracts were purified by silica gel column chromatography and then identified by thin layer chromatography (TLC and Fourier transform infrared spectroscopy (FT-IR. Results indicate that biosurfactant production yield remains constant and low while it is independent of the total culture biomass, carbon source, and temperature. A constant BS concentration in a culture broth with continuous degradation of crude oil implies that the BS producing microbes generate no more than the required amount of biosurfactants that enables biodegradation of the crude oil. Isolated pure strains were found to have higher specific production yields than the complex microbial marine community-consortia. The heavy oil fraction of crude oil has emerged as a promising substrate for BS production (by marine BS producers with fewer impurities in the final product. Furthermore, a particular strain isolated from sediments, Paracoccus marcusii, may be an optimal choice for bioremediation purposes as its biomass remains trapped in the hydrocarbon phase, not suffering from potential dilution effects by sea currents.

Biosurfactant production from marine hydrocarbon-degrading consortia and pure bacterial strains using crude oil as carbon source

Science.gov (United States)

Antoniou, Eleftheria; Fodelianakis, Stilianos; Korkakaki, Emmanouela; Kalogerakis, Nicolas

2015-01-01

Biosurfactants (BSs) are “green” amphiphilic molecules produced by microorganisms during biodegradation, increasing the bioavailability of organic pollutants. In this work, the BS production yield of marine hydrocarbon degraders isolated from Elefsina bay in Eastern Mediterranean Sea has been investigated. The drop collapse test was used as a preliminary screening test to confirm BS producing strains or mixed consortia. The community structure of the best consortia based on the drop collapse test was determined by 16S-rDNA pyrotag screening. Subsequently, the effect of incubation time, temperature, substrate and supplementation with inorganic nutrients, on BS production, was examined. Two types of BS – lipid mixtures were extracted from the culture broth; the low molecular weight BS Rhamnolipids and Sophorolipids. Crude extracts were purified by silica gel column chromatography and then identified by thin layer chromatography and Fourier transform infrared spectroscopy. Results indicate that BS production yield remains constant and low while it is independent of the total culture biomass, carbon source, and temperature. A constant BS concentration in a culture broth with continuous degradation of crude oil (CO) implies that the BS producing microbes generate no more than the required amount of BSs that enables biodegradation of the CO. Isolated pure strains were found to have higher specific production yields than the complex microbial marine community-consortia. The heavy oil fraction of CO has emerged as a promising substrate for BS production (by marine BS producers) with fewer impurities in the final product. Furthermore, a particular strain isolated from sediments, Paracoccus marcusii, may be an optimal choice for bioremediation purposes as its biomass remains trapped in the hydrocarbon phase, not suffering from potential dilution effects by sea currents. PMID:25904907

Purification, biochemical characterization, and genetic cloning of the phytase produced by Burkholderia sp. strain a13.

Science.gov (United States)

Graminho, Eduardo Rezende; Takaya, Naoki; Nakamura, Akira; Hoshino, Takayuki

2015-01-01

A phytase-producing bacterium, Burkholderia sp. a13 (JCM 30421), was isolated from Lake Kasumigaura by enrichment cultivation using minimum medium containing phytic acid as the sole phosphorus source. The phytase production by strain a13 was induced by the presence of phytic acid and repressed by the addition of glucose. The purified enzyme had a molecular weight of 44 kDa and a phytase activity of 174 μmol min(-1) mg(-1). The enzyme showed broad substrate specificity, but the highest activity was observed with phytic acid. The enzyme activity was strongly inhibited by Cu(2+), Zn(2+), Hg(2+), and iodoacetic acid, indicating the requirement of a thiol group for the activity. Genetic cloning reveals that the mature portion of this enzyme consists of 428 amino acids with a calculated molecular weight of 46 kDa. The amino acid sequence showed the highest similarity to the phytase produced by Hafnia alvei with 48% identity; it also contained histidine acid phosphatase (HAP) motifs (RHGXRXP and HD), indicating the classification of this enzyme in the HAP phytase family. We have successfully expressed the cloned gene in Escherichia coli from its putative initiation codon, showing that the gene actually encodes the phytase.

Triacetic acid lactone production in industrial Saccharomyces yeast strains

Science.gov (United States)

Triacetic acid lactone (TAL) is a potential platform chemical that can be produced in yeast. To evaluate the potential for industrial yeast strains to produce TAL, the g2ps1 gene encoding 2-pyrone synthase was transformed into thirteen industrial yeast strains of varied genetic background. TAL produ...

Foliar Application of Extract from an Azalomycin-Producing Streptomyces malaysiensis Strain MJM1968 Suppresses Yam Anthracnose Caused by Colletotrichum gloeosporioides.

Science.gov (United States)

Arunachalam Palaniyandi, Sasikumar; Yang, Seung Hwan; Suh, Joo-Woh

2016-06-28

Yam anthracnose caused by Colletotrichum gloeosporioides (C.g) is the most devastating disease of yam (Dioscorea sp.). In the present study, we evaluated the culture filtrate extract (CFE) of azalomycin-producing Streptomyces malaysiensis strain MJM1968 for the control of yam anthracnose. MJM1968 showed strong antagonistic activity against C.g in vitro. Furthermore, the MJM1968 CFE was tested for inhibition of spore germination in C.g, where it completely inhibited spore germination at a concentration of 50 μg/ml. To assess the in planta efficacy of the CFE and spores of MJM1968 against C.g, a detached leaf bioassay was conducted, which showed both the treatments suppressed anthracnose development on detached yam leaves. Furthermore, a greenhouse study was conducted to evaluate the CFE from MJM1968 as a fungicide for the control of yam anthracnose. The CFE non-treated plants showed a disease severity of >92% after 90 days of artificial inoculation with C.g, whereas the disease severity of CFE-treated and benomyl-treated yam plants was reduced to 26% and 15%, respectively, after 90 days. Analysis of the yam tubers from the CFE-treated and non-treated groups showed that tubers from the CFE-treated plants were larger than that of non-treated plants, which produced abnormal smaller tubers typical of anthracnose. This study demonstrated the utility of the CFE from S. malaysiensis strain MJM1968 as a biofungicide for the control of yam anthracnose.

Noble strain of Sparassis latifolia produces high content of β-glucan

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Dong Ju Lee

2015-08-01

Conclusions: These results indicate that the nucleotide sequences and the amino acid sequences of RPB2 can be used to identify individual Sparassis sp. The Sparassis strain CLM1 may be best for developing a remedy to prevent or treat cancer and other chronic diseases.

Screening of the White Button Mushroom (Agaricusbisporus Homokaryons and Producing New Hybrid Strain by SSR Markers

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marzieh nourashrafeddin

2018-02-01

Full Text Available Introduction: Edible white button mushroom (Agaricusbisporus is the most common edible mushroom in Iran and the world. The yield of this mushroom is less than the average of yield in the world because of strain degeneration and using strains with low yield. Most of the current hybrids are either identical or very similar to the first hybrids. Ongoing breeding programs are exploiting the variability in Agaricus germplasm to produce new varieties with better traits including higher yield and resistance to biotic and abiotic stresses. One of the breeding programs is F1 production from parental homokaryons crossing. These homokaryonsis were isolated among germinated basidiospores on the culture media. During the last decades, various molecular markers based on nucleic acid polymorphisms (such as Restriction Fragment Length Polymorphism, Random Amplification of Polymorphic DNA, Amplified fragment of Length Polymorphism, Inter Simple Sequence Repeat, Simple Sequence Repeat markers have been used to differentiate homokaryons and heterokaryons. Microsatellites consist of short tandem repeat motifs distributed throughout the genome. Microsatellites are usually highly polymorphic due to a high degree of variation in the number of repeats among individuals. Microsatellite markers are multiallelic and co-dominant and thus tend to be more informative than other marker systems. Microsatellite markers have been widely developed in animals and plants and more recently in fungal species. The presence of microsatellites in the genome of A. bisporus was previously reported. Materials and Methods: In this research, 160 germinated basidiospores were collected from commercially cultivated strain A15 and they were grown on compost extract agar (CEA. The mycelial growth rate of these160 isolates was evaluated at 25°C on CEA medium. 18 isolates with slow growing rate were selected from 160 isolates. In the next step, co-dominant SSR markers were used to homokaryons

Characterization of Extracellular Penicilin G Acylase Produced by A New Local Strain of Bacillus subtilis BAC4

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SUPARTONO

2008-06-01

Full Text Available Penicillin G acylase (PGA which catalyses penicillin G hydrolysis reaction is a key enzyme for the industrial production of penicilin G derivatives used in therapeutics. A new local strain of Bacillus subtilis BAC4 was found capable of producing extracellular PGA. However, characteristics of this extracellular PGA are not known. The goal of this research was to characterize the extracellular PGA produced by B. subtilis BAC4. Enzyme production was carried out by batch fermentation, followed by enzyme purification and characterization of the PGA. The PGA activity was determined by the Kornfeld method, with optimal activity for hydrolysing penicillin G observed at 43 °C and pH 8.5. The activation energy of penicillin G hydrolysis by the PGA of B. subtilis BAC4 was determined as 4.9 kcal.mol−1 and Vmax and Km values were found to be 0.7 μmole.min−1.mg−1 and 3.5 mM respectively. PGA catalytic activity was competitively inhibited by phenylacetic acid with an inhibition constant, Ki(PAA, of 347.2 mM. It was concluded that the extracellular PGA of B. subtilis BAC4 can hydrolyse penicillin G efficiently.

Characterization of Extracellular Penicilin G Acylase Produced by A New Local Strain of Bacillus subtilis BAC4

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SUPARTONO

2008-06-01

Full Text Available Penicillin G acylase (PGA which catalyses penicillin G hydrolysis reaction is a key enzyme for the industrial production of penicilin G derivatives used in therapeutics. A new local strain of Bacillus subtilis BAC4 was found capable of producing extracellular PGA. However, characteristics of this extracellular PGA are not known. The goal of this research was to characterize the extracellular PGA produced by B. subtilis BAC4. Enzyme production was carried out by batch fermentation, followed by enzyme purification and characterization of the PGA. The PGA activity was determined by the Kornfeld method, with optimal activity for hydrolysing penicillin G observed at 43 oC and pH 8.5. The activation energy of penicillin G hydrolysis by the PGA of B. subtilis BAC4 was determined as 4.9 kcal.mol-1 and Vmax and Km values were found to be 0.7 µmole.min-1.mg-1 and 3.5 mM respectively. PGA catalytic activity was competitively inhibited by phenylacetic acid with an inhibition constant, Ki(PAA, of 347.2 mM. It was concluded that the extracellular PGA of B. subtilis BAC4 can hydrolyse penicillin G efficiently.

Comparative genomics of citric-acid producing Aspergillus niger ATCC 1015 versus enzyme-producing CBS 513.88

Energy Technology Data Exchange (ETDEWEB)

Andersen, Mikael R.; Salazar, Margarita; Schaap, Peter; van de Vondervoort, Peter; Culley, David E.; Thykaer, Jette; Frisvad, Jens C.; Nielsen, Kristian F.; Albang, Richard; Albermann, Kaj; Berka, Randy; Braus, Gerhard; Braus-Stromeyer, Susanna A.; Corrochano, Luis; Dai, Ziyu; van Dijck, Piet; Hofmann, Gerald; Lasure, Linda L.; Magnuson, Jon K.; Menke, Hildegard; Meijer, Martin; Meijer, Susan; Nielsen, Jakob B.; Nielsen, Michael L.; van Ooyen, Albert; Pel, Herman J.; Poulsen, Lars; Samson, Rob; Stam, Hein; Tsang, Adrian; van den Brink, Johannes M.; ATkins, Alex; Aerts, Andrea; Shapiro, Harris; Pangilinan, Jasmyn; Salamov, Asaf; Lou, Yigong; Lindquist, Erika; Lucas, Susan; Grimwood, Jane; Grigoriev, Igor V.; Kubicek, Christian P.; Martinez, Diego; van Peij, Noel; Roubos, Johannes A.; Nielsen, Jens B.; Baker, Scott E.

2011-06-01

The filamentous fungus Aspergillus niger exhibits great diversity in its phenotype. It is found globally, both as marine and terrestrial strains, produces both organic acids and hydrolytic enzymes in high amounts, and some isolates exhibit pathogenicity. Although the genome of an industrial enzyme-producing A. niger strain (CBS 513.88) has already been sequenced, the versatility and diversity of this species compels additional exploration. We therefore undertook whole genome sequencing of the acidogenic A. niger wild type strain (ATCC 1015), and produced a genome sequence of very high quality. Only 15 gaps are present in the sequence and half the telomeric regions have been elucidated. Moreover, sequence information from ATCC 1015 was utilized to improve the genome sequence of CBS 513.88. Chromosome-level comparisons uncovered several genome rearrangements, deletions, a clear case of strain-specific horizontal gene transfer, and identification of 0.8 megabase of novel sequence. Single nucleotide polymorphisms per kilobase (SNPs/kb) between the two strains were found to be exceptionally high (average: 7.8, maximum: 160 SNPs/kb). High variation within the species was confirmed with exo-metabolite profiling and phylogenetics. Detailed lists of alleles were generated, and genotypic differences were observed to accumulate in metabolic pathways essential to acid production and protein synthesis. A transcriptome analysis revealed up-regulation of the electron transport chain, specifically the alternative oxidative pathway in ATCC 1015, while CBS 513.88 showed significant up regulation of genes associated with biosynthesis of amino acids that are abundant in glucoamylase A, tRNA-synthases and protein transporters.

Mexican unpasteurised fresh cheeses are contaminated with Salmonella spp., non-O157 Shiga toxin producing Escherichia coli and potential uropathogenic E. coli strains: A public health risk.

Science.gov (United States)

Guzman-Hernandez, Rosa; Contreras-Rodriguez, Araceli; Hernandez-Velez, Rosa; Perez-Martinez, Iza; Lopez-Merino, Ahide; Zaidi, Mussaret B; Estrada-Garcia, Teresa

2016-11-21

Fresh cheeses are a main garnish of Mexican food. Consumption of artisanal fresh cheeses is very common and most of them are made from unpasteurised cow milk. A total of 52 fresh unpasteurised cheeses of five different types were purchased from a variety of suppliers from Tabasco, Mexico. Using the most probable number method, 67% and 63% of samples were positive for faecal coliforms and E. coli, respectively; revealing their low microbiological quality. General hygienic conditions and practices of traditional cheese manufacturers were poor; most establishments had unclean cement floors, all lacked windows and doors screens, and none of the food-handlers wore aprons, surgical masks or bouffant caps. After analysing all E. coli isolates (121 strains) for the presence of 26 virulence genes, results showed that 9 (17%) samples were contaminated with diarrheagenic E. coli strains, 8 harboured non-O157 Shiga toxin producing E. coli (STEC), and one sample contained both STEC and diffusely adherent E. coli strains. All STEC strains carried the stx1 gene. Potential uropathogenic E. coli (UPEC) strains were isolated from 15 (29%) samples; the most frequent gene combination was fimA-agn43. Two samples were contaminated with Salmonella. The results demonstrated that unpasteurised fresh cheeses produced in Tabasco are of poor microbiological quality and may frequently harbour foodborne pathogens. Food safety authorities in Mexico need to conduct more rigorous surveillance of fresh cheeses. Furthermore, simple and inexpensive measures as establishing programs emphasizing good hand milking practices and hygienic manufacturing procedures may have a major effect on improving the microbiological quality of these food items. Copyright © 2016 Elsevier B.V. All rights reserved.

Determination of patulin producing activity and radiation sensitivity of fungisolated from Korean apples

Energy Technology Data Exchange (ETDEWEB)

Kim, Dong Ho; Jo, Min Ho [Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup (Korea, Republic of)

2017-06-15

Patulin is a mycotoxin produced by a variety of molds, especially within genera Penicillium, Aspergillus and Byssochlamys growing on various fruits. In this study, patulin producing activities and the effects of a gamma irradiation on the control and/or sterilization of fungal strains isolated from Korean apples, Malus pumila var. dulcissima, were evaluated. Nine fungal strains; five strains of genus Penicillium and one strains of genus Glomerella, Giberella, Alternaria and Galactomyces were isolated and identified by the similarity analysis based on the nucleotide sequence of the ITS5-5.8S-ITS4 region. Among the isolated strains, four Penicillium strains and a Glomerella showed patulin producing activities. The maximal patulin-producing activity of P. griseofulvum ATCC 46037, a standard strain of patulin-producing fungi, was 1,211.5 ppm in a 5-GYEP broth medium, while those of the isolated fungi reached to 27.4⁓134.2 ppm. Patulin-producing levels were dependent on the carbon sources and maximal production of the patulin by P. griseofulvum, P. crustosum, I-3, I-6, I-7 and I-8 was observed in a broth media containing glycerol, fructose, glycerol, glucose, lactose and fructose, respectively. The D10-values of the conidia of tested strains in an aqueous suspension were calculated in the range of 0.25⁓0.64 kGy. In conclusion, although the patulin producing activities of the isolated fungi were significantly lower than those of standard strains, it cannot deny the possibility of an patulin contamination of the Korean apples. Therefore, gamma ray irradiation (1.0 kGy) after harvest of apples could be applied to prevent the growth of a patulin producing molds for a safe distribution.

Determination of patulin producing activity and radiation sensitivity of fungisolated from Korean apples

International Nuclear Information System (INIS)

Kim, Dong Ho; Jo, Min Ho

2017-01-01

Patulin is a mycotoxin produced by a variety of molds, especially within genera Penicillium, Aspergillus and Byssochlamys growing on various fruits. In this study, patulin producing activities and the effects of a gamma irradiation on the control and/or sterilization of fungal strains isolated from Korean apples, Malus pumila var. dulcissima, were evaluated. Nine fungal strains; five strains of genus Penicillium and one strains of genus Glomerella, Giberella, Alternaria and Galactomyces were isolated and identified by the similarity analysis based on the nucleotide sequence of the ITS5-5.8S-ITS4 region. Among the isolated strains, four Penicillium strains and a Glomerella showed patulin producing activities. The maximal patulin-producing activity of P. griseofulvum ATCC 46037, a standard strain of patulin-producing fungi, was 1,211.5 ppm in a 5-GYEP broth medium, while those of the isolated fungi reached to 27.4⁓134.2 ppm. Patulin-producing levels were dependent on the carbon sources and maximal production of the patulin by P. griseofulvum, P. crustosum, I-3, I-6, I-7 and I-8 was observed in a broth media containing glycerol, fructose, glycerol, glucose, lactose and fructose, respectively. The D10-values of the conidia of tested strains in an aqueous suspension were calculated in the range of 0.25⁓0.64 kGy. In conclusion, although the patulin producing activities of the isolated fungi were significantly lower than those of standard strains, it cannot deny the possibility of an patulin contamination of the Korean apples. Therefore, gamma ray irradiation (1.0 kGy) after harvest of apples could be applied to prevent the growth of a patulin producing molds for a safe distribution

Purification, cloning and characterisation of two forms of thermostable and highly active cellobiohydrolase I (Cel7A) produced by the industrial strain of Chrysosporium lucknowense

NARCIS (Netherlands)

Gusakov, A.V.; Sinitsyn, A.P.; Salanovich, T.N.; Bukhtojarov, F.E.; Markov, A.V.; Ustinov, B.B.; Zeijl, C.V.; Punt, P.; Burlingame, R.

2005-01-01

Two forms of cellobiohydrolase I (CBH I, Cel7A) were purified from the culture ultrafiltrate of a mutant strain of the fungus Chrysosporium lucknowense, an industrial producer of cellulases and hemicellulases. The enzymes had different molecular masses (52 and 65 kDa, SDS-PAGE data) but the same pI

Developmentally regulated expression by Trypanosoma cruzi of molecules that accelerate the decay of complement C3 convertases

International Nuclear Information System (INIS)

Rimoldi, M.T.; Sher, A.; Heiny, A.; Lituchy, A.; Hammer, C.H.; Joiner, K.

1988-01-01

The authors recently showed that culture-derived metacyclic trypomastigotes (CMT), but not epimastigotes (Epi), of the Miranda 99 strain of Trypanosoma cruzi evade lysis by the human alternative complement pathway because of inefficient binding of factor B to complement component C3b on the parasite surface. These results suggested that CMT and tissue-culture-derived trypomastigotes (TCT), which also activate the alternative pathway poorly, might produce a molecule capable of interfering with factor B binding to C3b. They now demonstrate that CMT and TCT lysates, as well as molecules spontaneously shed from CMT and TCT but not Epi, accelerate decay of 125 I-labeled factor Bb from the alternative-pathway C3 convertase (C3bBb) assembled on zymosan or Epi and also accelerate decay of the classical-pathway C3 convertase (C4b2a) on sheep erythrocytes. Parasites metabolically labeled with [ 35 S]methionine spontaneously shed a limited number of radioactive components, ranging in molecular mass from 86 to 155 kDa for trypomastigotes and 25 to 80 kDa for Epi. Decay-accelerating activity within supernatants is inactivated by papain and is coeluted with 35 S-containing polypeptides on FPLC anion-exchange chromatography, suggesting that the active constituents are protein molecules. Molecules with decay-accelerating activity may explain the developmentally regulated resistance to complement-mediated lysis in infective and vertebrate stages for T. cruzi life cycle

Exotic helium molecules

International Nuclear Information System (INIS)

Portier, M.

2007-12-01

We study the photo-association of an ultracold cloud of magnetically trapped helium atoms: pairs of colliding atoms interact with one or two laser fields to produce a purely long range 4 He 2 (2 3 S 1 -2 3 P 0 ) molecule, or a 4 He 2 (2 3 S 1 -2 3 S 1 ) long range molecule. Light shifts in one photon photo-association spectra are measured and studied as a function of the laser polarization and intensity, and the vibrational state of the excited molecule. They result from the light-induced coupling between the excited molecule, and bound and scattering states of the interaction between two metastable atoms. Their analysis leads to the determination of the scattering length a = (7.2 ± 0.6) ruling collisions between spin polarized atoms. The two photon photo-association spectra show evidence of the production of polarized, long-range 4 He 2 (2 3 S 1 -2 3 S 1 ) molecules. They are said to be exotic as they are made of two metastable atoms, each one carrying a enough energy to ionize the other. The corresponding lineshapes are calculated and decomposed in sums and products of Breit-Wigner and Fano profiles associated to one and two photon processes. The experimental spectra are fit, and an intrinsic lifetime τ = (1.4 ± 0.3) μs is deduced. It is checked whether this lifetime could be limited by spin-dipole induced Penning autoionization. This interpretation requires that there is a quasi-bound state close to the dissociation threshold in the singlet interaction potential between metastable helium atoms for the theory to match the experiment. (author)

Characteristics of Shigatoxin-Producing Escherichia coli Strains Isolated during 2010–2014 from Human Infections in Switzerland

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Lisa Fierz

2017-08-01

Full Text Available Objectives: The aim of this study was to characterize a collection of 95 Shigatoxin-producing E.coli (STEC isolated from human patients in Switzerland during 2010–2014.Methods: We performed O and H serotyping and molecular subtyping.Results: The five most common serogroups were O157, O145, O26, O103, and O146. Of the 95 strains, 35 (36.8% carried stx1 genes only, 43 strains (45.2% carried stx2 and 17 (17.9% harbored combinations of stx1 and stx2 genes. Stx1a (42 strains and stx2a (32 strains were the most frequently detected stx subtypes. Genes for intimin (eae, hemolysin (hly, iron-regulated adhesion (iha, and the subtilase cytotoxin subtypes subAB1, subAB2-1, subAB2-2, or subAB2-3 were detected in 70.5, 83.2, 74.7, and 20% of the strains, respectively. Multilocus sequence typing assigned the majority (58.9% of the isolates to five different clonal complexes (CC, 11, 32, 29, 20, and 165, respectively. CC11 included all O157:[H7] and O55:[H7] isolates. CC32 comprised O145:[H28] isolates, and O145:[H25] belonged to sequence type (ST 342. CC29 contained isolates of the O26:[H11], O111:[H8] and O118:[Hnt] serogroups, and CC20 encompassed isolates of O51:H49/[Hnt] and O103:[H2]. CC165 included isolates typed O80:[H2]-ST301, all harboring stx2d, eae-ξ, hly, and 66.7% additionally harboring iha. All O80:[H2]-ST301 strains harbored at least 7 genes carried by pS88, a plasmid associated with extraintestinal virulence. Compared to data from Switzerland from the years 2000–2009, an increase of the proportion of non-O157 STEC infections was observed as well as an increase of infections due to STEC O146. By contrast, the prevalence of the highly virulent German clone STEC O26:[H11]-ST29 decreased from 11.3% during 2000–2009 to 1.1% for the time span 2010–2014. The detection of O80:[H2]-ST301 harboring stx2d, eae-ξ, hly, iha, and pS88 related genes suggests an ongoing emergence in Switzerland of an unusual, highly pathogenic STEC serotype

Fatal necrotizing fasciitis due to necrotic toxin-producing Escherichia coli strain

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C. Gallois

2015-11-01

Full Text Available We report a fatal case of necrotizing soft tissues infection caused by an Escherichia coli strain belonging to phylogenetic group C and harbouring numerous virulence factors reported to be part of a pathogenicity island (PAI such as PAI IIJ96 and conserved virulence plasmidic region.

Draft Genome Sequence of a Cellulase-Producing Psychrotrophic Paenibacillus Strain, IHB B 3415, Isolated from the Cold Environment of the Western Himalayas, India.

Science.gov (United States)

Dhar, Hena; Swarnkar, Mohit Kumar; Gulati, Arvind; Singh, Anil Kumar; Kasana, Ramesh Chand

2015-02-19

Paenibacillus sp. strain IHB B 3415 is a cellulase-producing psychrotrophic bacterium isolated from a soil sample from the cold deserts of Himachal Pradesh, India. Here, we report an 8.44-Mb assembly of its genome sequence with a G+C content of 50.77%. The data presented here will provide insights into the mechanisms of cellulose degradation at low temperature. Copyright © 2015 Dhar et al.

Apparatus Producing an Even Distribution of Strain into Carries

Science.gov (United States)

Hrabovský, Leopold

2017-10-01

In many high-rise residential buildings or multi-storey warehouses, machinery, so called lifts, is used for the vertical transportation of people or weights between two or more altitudinally distant places. Carriers used for lifts are steel ropes or sprocket chains, on which a cage or a counterbalance is hinged. Apparatus of all carriers, attached to the hinge of the cage or counterbalance, should be even. This can be made only by hammer hinge. Fixed or springe hinge cannot be a perfect equalizing apparatus. This article describes an apparatus, which allows an even distribution of the strain into lift carriers, which use springe hinge of carrier ropes.

Development of intra-strain self-cloning procedure for breeding baker's yeast strains.

Science.gov (United States)

Nakagawa, Youji; Ogihara, Hiroyuki; Mochizuki, Chisato; Yamamura, Hideki; Iimura, Yuzuru; Hayakawa, Masayuki

2017-03-01

Previously reported self-cloning procedures for breeding of industrial yeast strains require DNA from other strains, plasmid DNA, or mutagenesis. Therefore, we aimed to construct a self-cloning baker's yeast strain that exhibits freeze tolerance via an improved self-cloning procedure. We first disrupted the URA3 gene of a prototrophic baker's yeast strain without the use of any marker gene, resulting in a Δura3 homozygous disruptant. Then, the URA3 gene of the parental baker's yeast strain was used as a selection marker to introduce the constitutive TDH3 promoter upstream of the PDE2 gene encoding high-affinity cyclic AMP phosphodiesterase. This self-cloning procedure was performed without using DNA from other Saccharomyces cerevisiae strains, plasmid DNA, or mutagenesis and was therefore designated an intra-strain self-cloning procedure. Using this self-cloning procedure, we succeeded in producing self-cloning baker's yeast strains that harbor the TDH3p-PDE2 gene heterozygously and homozygously, designated TDH3p-PDE2 hetero and TDH3p-PDE2 homo strains, respectively. These self-cloning strains expressed much higher levels of PDE2 mRNA than the parental strain and exhibited higher viability after freeze stress, as well as higher fermentation ability in frozen dough, when compared with the parental strain. The TDH3p-PDE2 homo strain was genetically more stable than the TDH3p-PDE2 hetero strain. These results indicate that both heterozygous and homozygous strains of self-cloning PDE2-overexpressing freeze-tolerant strains of industrial baker's yeast can be prepared using the intra-strain self-cloning procedure, and, from a practical viewpoint, the TDH3p-PDE2 homo strain constructed in this study is preferable to the TDH3p-PDE2 hetero strain for frozen dough baking. Copyright © 2016 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Analysis of Large-Strain Extrusion Machining with Different Chip Compression Ratios

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Wen Jun Deng

2012-01-01

Full Text Available Large-Strain Extrusion Machining (LSEM is a novel-introduced process for deforming materials to very high plastic strains to produce ultra-fine nanostructured materials. Before the technique can be exploited, it is important to understand the deformation behavior of the workpiece and its relationship to the machining parameters and friction conditions. This paper reports finite-element method (FEM analysis of the LSEM process to understand the evolution of temperature field, effective strain, and strain rate under different chip compression ratios. The cutting and thrust forces are also analyzed with respect to time. The results show that LSEM can produce very high strains by changing in the value of chip compression ratio, thereby enabling the production of nanostructured materials. The shape of the chip produced by LSEM can also be geometrically well constrained.

The new allelic variant of the subtilase cytotoxin (subAB2) is common among Shiga toxin-producing Escherichia coli strains from large game animals and their meat and meat products.

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Sánchez, Sergio; Díaz-Sánchez, Sandra; Martínez, Remigio; Llorente, María Teresa; Herrera-León, Silvia; Vidal, Dolors

2013-10-25

Subtilase cytotoxin (SubAB) is an AB5 toxin produced by Shiga toxin (Stx)-producing Escherichia coli (STEC) strains usually lacking the eae gene product intimin. Two allelic variants of SubAB encoding genes have been described: subAB1, located on a plasmid, and subAB2, located on a pathogenicity island (PAI) together with tia gene. While subAB1 has been reported to be more frequent among bovine strains, subAB2 has been mainly associated with strains from small ruminants. We investigated the presence of the two variants of subAB among 59 eae-negative STEC from large game animals (deer and wild boar) and their meat and meat products in order to assess the role of other species in the epidemiology of subAB-positive, eae-negative STEC. For this approach, the strains were PCR-screened for the presence of subAB, including the specific detection of both allelic variants, for the presence of saa, tia and sab, and for stx subtyping. Overall, subAB genes were detected in 71.2% of the strains: 84.1% of the strains from deer and 33.3% of the strains from wild boar. Most of them (97.6%) possessed subAB2 and most of these subAB2-positive strains (92.7%) were also positive for tia and negative for saa, suggesting the presence of the subAB2-harbouring PAI. Subtype stx2b was present in most of the strains (67.8%) and a statistically significant association could be established between subAB2 and stx2b. Our results suggest that large game animals, mainly deer, may represent an important animal reservoir of subAB2-positive, eae-negative STEC, and also highlight the risk of human infection posed by the consumption of large game meat and meat products. Copyright © 2013 Elsevier B.V. All rights reserved.

Collagen-like proteins in pathogenic E. coli strains.

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Neelanjana Ghosh

Full Text Available The genome sequences of enterohaemorrhagic E. coli O157:H7 strains show multiple open-reading frames with collagen-like sequences that are absent from the common laboratory strain K-12. These putative collagens are included in prophages embedded in O157:H7 genomes. These prophages carry numerous genes related to strain virulence and have been shown to be inducible and capable of disseminating virulence factors by horizontal gene transfer. We have cloned two collagen-like proteins from E. coli O157:H7 into a laboratory strain and analysed the structure and conformation of the recombinant proteins and several of their constituting domains by a variety of spectroscopic, biophysical, and electron microscopy techniques. We show that these molecules exhibit many of the characteristics of vertebrate collagens, including trimer formation and the presence of a collagen triple helical domain. They also contain a C-terminal trimerization domain, and a trimeric α-helical coiled-coil domain with an unusual amino acid sequence almost completely lacking leucine, valine or isoleucine residues. Intriguingly, these molecules show high thermal stability, with the collagen domain being more stable than those of vertebrate fibrillar collagens, which are much longer and post-translationally modified. Under the electron microscope, collagen-like proteins from E. coli O157:H7 show a dumbbell shape, with two globular domains joined by a hinged stalk. This morphology is consistent with their likely role as trimeric phage side-tail proteins that participate in the attachment of phage particles to E. coli target cells, either directly or through assembly with other phage tail proteins. Thus, collagen-like proteins in enterohaemorrhagic E. coli genomes may have a direct role in the dissemination of virulence-related genes through infection of harmless strains by induced bacteriophages.

Carbon-flux distribution within Streptomyces coelicolor metabolism: a comparison between the actinorhodin-producing strain M145 and its non-producing derivative M1146.

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Fabien Coze

Full Text Available Metabolic Flux Analysis is now viewed as essential to elucidate the metabolic pattern of cells and to design appropriate genetic engineering strategies to improve strain performance and production processes. Here, we investigated carbon flux distribution in two Streptomyces coelicolor A3 (2 strains: the wild type M145 and its derivative mutant M1146, in which gene clusters encoding the four main antibiotic biosynthetic pathways were deleted. Metabolic Flux Analysis and (13C-labeling allowed us to reconstruct a flux map under steady-state conditions for both strains. The mutant strain M1146 showed a higher growth rate, a higher flux through the pentose phosphate pathway and a higher flux through the anaplerotic phosphoenolpyruvate carboxylase. In that strain, glucose uptake and the flux through the Krebs cycle were lower than in M145. The enhanced flux through the pentose phosphate pathway in M1146 is thought to generate NADPH enough to face higher needs for biomass biosynthesis and other processes. In both strains, the production of NADPH was higher than NADPH needs, suggesting a key role for nicotinamide nucleotide transhydrogenase for redox homeostasis. ATP production is also likely to exceed metabolic ATP needs, indicating that ATP consumption for maintenance is substantial.Our results further suggest a possible competition between actinorhodin and triacylglycerol biosynthetic pathways for their common precursor, acetyl-CoA. These findings may be instrumental in developing new strategies exploiting S. coelicolor as a platform for the production of bio-based products of industrial interest.

Isolation and functional characterization of a biosurfactant produced by a new and promising strain of Oleomonas sagaranensis AT18.

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Saimmai, Atipan; Rukadee, Onkamon; Onlamool, Theerawat; Sobhon, Vorasan; Maneerat, Suppasil

2012-10-01

Biosurfactant-producing bacteria were isolated from mangrove sediment in southern Thailand. Isolates were screened for biosurfactant production by using the surface tension test. The highest reduction of surface tension was achieved with a bacterial strain which was identified by 16S rRNA gene sequencing as Oleomonas sagaranensis AT18. It has also been investigated using different carbon and nitrogen sources. It showed that the strain was able to grow and reduce the surface tension of the culture supernatant to 25 mN/m. In all 5.30 g of biosurfactant yield was obtained after 54 h of cultivation by using molasses and NaNO₃ as carbon and nitrogen sources, respectively. The biosurfactant recovery by chloroform:methanol extraction showed a small critical micelle concentration value (8 mg/l), thermal and pH stability with respect to surface tension reduction. It also showed emulsification activity and a high level of salt concentration. The biosurfactant obtained was confirmed as a glycolipid by using a biochemical test, FT-IR and mass spectra. The crude biosurfactant showed a broad spectrum of antimicrobial activity and also had the ability to emulsify oil and enhance PAHs solubility.

Purification and characterization of a fibrinolytic enzyme produced from Bacillus sp. strain CK 11-4 screened from Chungkook-Jang.

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Kim, W; Choi, K; Kim, Y; Park, H; Choi, J; Lee, Y; Oh, H; Kwon, I; Lee, S

1996-01-01

Bacillus sp. strain CK 11-4, which produces a strongly fibrinolytic enzyme, was screened from Chungkook-Jang, a traditional Korean fermented-soybean sauce. The fibrinolytic enzyme (CK) was purified from supernatant of Bacillus sp. strain CK 11-4 culture broth and showed thermophilic, hydrophilic, and strong fibrinolytic activity. The optimum temperature and pH were 70 degrees C and 10.5, respectively, and the molecular weight was 28,200 as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The first 14 amino acids of the N-terminal sequence of CK are Ala-Gin-Thr-Val-Pro-Tyr-Gly-Ile-Pro-Leu-Ile-Lys-Ala-Asp. This sequence is identical to that of subtilisin Carlsberg and different from that of nattokinase, but CK showed a level of fibrinolytic activity that was about eight times higher than that of subtilisin Carlsberg. The amidolytic activity of CK increased about twofold at the initial state of the reaction when CK enzyme was added to a mixture of plasminogen and substrate (H-D-Val-Leu-Lys-pNA). A similar result was also obtained from fibrin plate analysis. PMID:8779587

Synthesis of siderophores by strains of Staphylococcus cohnii isolated from various environments.

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Szarapińska-Kwaszewska, Jadwiga; Farkas, Lukasz I

2003-01-01

Siderophore activity as the feature of microorganisms enabling colonization of human body and the survival in inanimate environment was investigated in 108 strains of Staphylococcus cohnii; S. cohnii ssp. cohnii (50 strains) and S. cohnii ssp. urealyticus (58 strains). Strains were isolated from people, hospital and non-hospital environment. Highest siderophore activity was noted in strains S. cohnii ssp. urealyticus particularly from the inanimate environments origin. In 86% analyzed strains siderophores of hydroxamate class were detected. Larger amounts of these compounds were synthesized in strains S. cohnii ssp. urealyticus. Strains belonging to both subspecies from human origin showed lower activity of siderophores (total pool) and did not produce hydroxamate class chelators or produced very small amounts of these compounds.

Identification of human-pathogenic strains of Shiga toxin-producing Escherichia coli from food by a combination of serotyping and molecular typing of Shiga toxin genes.

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Beutin, Lothar; Miko, Angelika; Krause, Gladys; Pries, Karin; Haby, Sabine; Steege, Katja; Albrecht, Nadine

2007-08-01

We examined 219 Shiga toxin-producing Escherichia coli (STEC) strains from meat, milk, and cheese samples collected in Germany between 2005 and 2006. All strains were investigated for their serotypes and for genetic variants of Shiga toxins 1 and 2 (Stx1 and Stx2). stx(1) or variant genes were detected in 88 (40.2%) strains and stx(2) and variants in 177 (80.8%) strains. Typing of stx genes was performed by stx-specific PCRs and by analysis of restriction fragment length polymorphisms (RFLP) of PCR products. Major genotypes of the Stx1 (stx(1), stx(1c), and stx(1d)) and the Stx2 (stx(2), stx(2d), stx(2-O118), stx(2e), and stx(2g)) families were detected, and multiple types of stx genes coexisted frequently in STEC strains. Only 1.8% of the STEC strains from food belonged to the classical enterohemorrhagic E. coli (EHEC) types O26:H11, O103:H2, and O157:H7, and only 5.0% of the STEC strains from food were positive for the eae gene, which is a virulence trait of classical EHEC. In contrast, 95 (43.4%) of the food-borne STEC strains carried stx(2) and/or mucus-activatable stx(2d) genes, an indicator for potential high virulence of STEC for humans. Most of these strains belonged to serotypes associated with severe illness in humans, such as O22:H8, O91:H21, O113:H21, O174:H2, and O174:H21. stx(2) and stx(2d) STEC strains were found frequently in milk and beef products. Other stx types were associated more frequently with pork (stx(2e)), lamb, and wildlife meat (stx(1c)). The combination of serotyping and stx genotyping was found useful for identification and for assignment of food-borne STEC to groups with potential lower and higher levels of virulence for humans.

In silico Prediction, in vitro Antibacterial Spectrum, and Physicochemical Properties of a Putative Bacteriocin Produced by Lactobacillus rhamnosus Strain L156.4

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Letícia de C. Oliveira

2017-05-01

Full Text Available A bacteriocinogenic Lactobacillus rhamnosus L156.4 strain isolated from the feces of NIH mice was identified by 16S rRNA gene sequencing and MALDI-TOF mass spectrometry. The entire genome was sequenced using Illumina, annotated in the PGAAP, and RAST servers, and deposited. Conserved genes associated with bacteriocin synthesis were predicted using BAGEL3, leading to the identification of an open reading frame (ORF that shows homology with the L. rhamnosus GG (ATCC 53103 prebacteriocin gene. The encoded protein contains a conserved protein motif associated a structural gene of the Enterocin A superfamily. We found ORFs related to the prebacteriocin, immunity protein, ABC transporter proteins, and regulatory genes with 100% identity to those of L. rhamnosus HN001. In this study, we provide evidence of a putative bacteriocin produced by L. rhamnosus L156.4 that was further confirmed by in vitro assays. The antibacterial activity of the substances produced by this strain was evaluated using the deferred agar-spot and spot-on-the lawn assays, and a wide antimicrobial activity spectrum against human and foodborne pathogens was observed. The physicochemical characterization of the putative bacteriocin indicated that it was sensitive to proteolytic enzymes, heat stable and maintained its antibacterial activity in a pH ranging from 3 to 9. The activity against Lactobacillus fermentum, which was used as an indicator strain, was detected during bacterial logarithmic growth phase, and a positive correlation was confirmed between bacterial growth and production of the putative bacteriocin. After a partial purification from cell-free supernatant by salt precipitation, the putative bacteriocin migrated as a diffuse band of approximately 1.0–3.0 kDa by SDS-PAGE. Additional studies are being conducted to explore its use in the food industry for controlling bacterial growth and for probiotic applications.

In silico Prediction, in vitro Antibacterial Spectrum, and Physicochemical Properties of a Putative Bacteriocin Produced by Lactobacillus rhamnosus Strain L156.4

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Oliveira, Letícia de C.; Silveira, Aline M. M.; Monteiro, Andréa de S.; dos Santos, Vera L.; Nicoli, Jacques R.; Azevedo, Vasco A. de C.; Soares, Siomar de C.; Dias-Souza, Marcus V.; Nardi, Regina M. D.

2017-01-01

A bacteriocinogenic Lactobacillus rhamnosus L156.4 strain isolated from the feces of NIH mice was identified by 16S rRNA gene sequencing and MALDI-TOF mass spectrometry. The entire genome was sequenced using Illumina, annotated in the PGAAP, and RAST servers, and deposited. Conserved genes associated with bacteriocin synthesis were predicted using BAGEL3, leading to the identification of an open reading frame (ORF) that shows homology with the L. rhamnosus GG (ATCC 53103) prebacteriocin gene. The encoded protein contains a conserved protein motif associated a structural gene of the Enterocin A superfamily. We found ORFs related to the prebacteriocin, immunity protein, ABC transporter proteins, and regulatory genes with 100% identity to those of L. rhamnosus HN001. In this study, we provide evidence of a putative bacteriocin produced by L. rhamnosus L156.4 that was further confirmed by in vitro assays. The antibacterial activity of the substances produced by this strain was evaluated using the deferred agar-spot and spot-on-the lawn assays, and a wide antimicrobial activity spectrum against human and foodborne pathogens was observed. The physicochemical characterization of the putative bacteriocin indicated that it was sensitive to proteolytic enzymes, heat stable and maintained its antibacterial activity in a pH ranging from 3 to 9. The activity against Lactobacillus fermentum, which was used as an indicator strain, was detected during bacterial logarithmic growth phase, and a positive correlation was confirmed between bacterial growth and production of the putative bacteriocin. After a partial purification from cell-free supernatant by salt precipitation, the putative bacteriocin migrated as a diffuse band of approximately 1.0–3.0 kDa by SDS-PAGE. Additional studies are being conducted to explore its use in the food industry for controlling bacterial growth and for probiotic applications. PMID:28579977

Characteristics of bacteremia caused by extended-spectrum beta-lactamase-producing Proteus mirabilis.

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Kurihara, Yoko; Hitomi, Shigemi; Oishi, Tsuyoshi; Kondo, Tsukasa; Ebihara, Tsugio; Funayama, Yasunori; Kawakami, Yasushi

2013-10-01

Although Proteus mirabilis is a common human pathogen, bacteremia caused by the organism, especially strains producing extended-spectrum beta-lactamase (ESBL), has rarely been investigated. We examined 64 cases of P. mirabilis bacteremia identified in the Minami Ibaraki Area, Japan, between 2001 and 2010 and compared the characteristics of cases with ESBL-producing and ESBL-non-producing strains (13 and 51 cases, respectively). All ESBL-producing strains with the gene encoding the CTX-M-2-group were genetically nonidentical. Isolation of ESBL-producing strains was significantly associated with onset in a hospital (p = 0.030), receiving hemodialysis (p = 0.0050), and previous antibiotic use within 1 month (p = 0.036; especially penicillin and/or cephalosporin (p = 0.010) and fluoroquinolone (p = 0.0069)). Isolation was also associated with inappropriate antibiotic therapy on the 1st and 4th days (p = 0.011 and 0.032, respectively) but not with mortality on the 30th day. These findings indicate that, for P. mirabilis bacteremia, isolation of ESBL-producing strains causes delay of initiating appropriate antimicrobial therapy but may not be associated with mortality.

Chemical reactivities of some interstellar molecules

Energy Technology Data Exchange (ETDEWEB)

Chadha, M S

1980-01-01

Work in the area of chemical evolution during the last 25 years has revealed the formation of a large number of biologically important molecules produced from simple starting materials under relatively simple experimental conditions. Much of this work has resulted from studies under atmospheres simulating that of the primitive earth or other planets. During the last decade, progress has also been made in the identification of chemical constituents of interstellar medium. A number of these molecules are the same as those identified in laboratory experiments. Even though the conditions of the laboratory experiments are vastly different from those of the cool, low-density interstellar medium, some of the similarities in composition are too obvious to go unnoticed. The present paper highlights some of the similarities in the composition of prebiotic molecules and those discovered in the interstellar medium. Also the chemical reactions which some of the common molecules e.g., NH3, HCN, H2CO, HC(triple bond)-C-CN etc. can undergo are surveyed.

Growth kinetic and fuel quality parameters as selective criterion for screening biodiesel producing cyanobacterial strains.

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Gayathri, Manickam; Shunmugam, Sumathy; Mugasundari, Arumugam Vanmathi; Rahman, Pattanathu K S M; Muralitharan, Gangatharan

2018-01-01

The efficiency of cyanobacterial strains as biodiesel feedstock varies with the dwelling habitat. Fourteen indigenous heterocystous cyanobacterial strains from rice field ecosystem were screened based on growth kinetic and fuel parameters. The highest biomass productivity was obtained in Nostoc punctiforme MBDU 621 (19.22mg/L/day) followed by Calothrix sp. MBDU 701 (13.43mg/L/day). While lipid productivity and lipid content was highest in Nostoc spongiaeforme MBDU 704 (4.45mg/L/day and 22.5%dwt) followed by Calothrix sp. MBDU 701 (1.54mg/L/day and 10.75%dwt). Among the tested strains, Nostoc spongiaeforme MBDU 704 and Nostoc punctiforme MBDU 621 were selected as promising strains for good quality biodiesel production by Preference Ranking Organization Method for Enrichment Evaluation (PROMETHEE) and Graphical Analysis for Interactive Assistance (GAIA) analysis. Copyright © 2017 Elsevier Ltd. All rights reserved.

Trapping molecules in two and three dimensions

International Nuclear Information System (INIS)

Pinkse, PW.H.; Junglen, T.; Rieger, T.; Rangwala, S.A.; Windpassinger, P.; Rempe, G.

2005-01-01

Full text: Cold molecules offer a new testing ground for quantum-physical effects in nature. For example, producing slow beams of large molecules could push experiments studying the boundary between quantum interference and classical particles up towards ever heavier particles. Moreover, cold molecules, in particular YbF, seem an attractive way to narrow down the constraints on the value of the electron dipole moment and finally, quantum information processing using chains of cold polar molecules or vibrational states in molecules have been proposed. All these proposals rely on advanced production and trapping techniques, most of which are still under development. Therefore, novel production and trapping techniques for cold molecules could offer new possibilities not found in previous methods. Electric traps hold promise for deep trap potentials for neutral molecules. Recently we have demonstrated two-dimensional trapping of polar molecules in a four-wire guide using electrostatic and electrodynamic trapping techniques. Filled from a thermal effusive source, such a guide will deliver a beam of slow molecules, which is an ideal source for interferometry experiments with large molecules, for instance. Here we report about the extension of this work to three-dimensional trapping. Polar molecules with a positive Stark shift can be trapped in the minimum of an electrostatic field. We have successfully tested a large volume electrostatic trap for ND3 molecules. A special feature of this trap is that it can be loaded continuously from an electrostatic guide, at a temperature of a few hundred mK. (author)

The Draft Genome Sequence of Clostridium sp. Strain NJ4, a Bacterium Capable of Producing Butanol from Inulin Through Consolidated Bioprocessing.

Science.gov (United States)

Jiang, Yujia; Lu, Jiasheng; Chen, Tianpeng; Yan, Wei; Dong, Weiliang; Zhou, Jie; Zhang, Wenming; Ma, Jiangfeng; Jiang, Min; Xin, Fengxue

2018-05-23

A novel butanogenic Clostridium sp. NJ4 was successfully isolated and characterized, which could directly produce relatively high titer of butanol from inulin through consolidated bioprocessing (CBP). The assembled draft genome of strain NJ4 is 4.09 Mp, containing 3891 encoded protein sequences with G+C content of 30.73%. Among these annotated genes, a levanase, a hypothetical inulinase, and two bifunctional alcohol/aldehyde dehydrogenases (AdhE) were found to play key roles in the achievement of ABE production from inulin through CBP.

Production and Purification of a Novel Xanthan Lyase from a Xanthan-Degrading Microbacterium sp. Strain XT11

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Fan Yang

2014-01-01

Full Text Available A xanthan lyase was produced and purified from the culture supernatant of an excellent xanthan-modifying strain Microbacterium sp. XT11. Xanthan lyase was induced by xanthan but was inhibited by its structural monomer glucose. Its production by strain XT11 is much higher than that by all other reported strains. The purified xanthan lyase has a molecular mass of 110 kDa and a specific activity of 28.2 U/mg that was much higher than that of both Paenibacillus and Bacillus lyases. It was specific on the pyruvated mannosyl residue in the intact xanthan molecule, but about 50% lyase activity remained when xanthan was partially depyruvated. Xanthan lyase was optimally active at pH 6.0–6.5 and 40°C and alkali-tolerant at a high pH value of 11.0. The metal ions including K+, Ca2+, Na+, Mg2+, Mn2+, and Li+ strongly stimulated xanthan lyase activity but ions Zn2+ and Cu2+ were its inhibitor. Xanthan lyase should be a novel enzyme different from the other xanthan lyases ever reported.

Mechanism of Excretion of a Bacterial Proteinase: Demonstration of Two Proteolytic Enzymes Produced by a Sarcina Strain (Coccus P)

Energy Technology Data Exchange (ETDEWEB)

SARNER, NITZA Z; BISSELL, MINA J; GIROLAMO, MARIO Di; GORINI, LUIGI

1970-06-29

A Sarcina strain (Coccus P) produces two proteolytic enzymes. One is found only extracellularly, is far more prevalent, and is actively excreted during exponential growth. It is the enzyme responsible for the known strong proteolytic activity of the cultures of this strain. A second protease is, however, produced which remains associated with the intact cells but is released by the protoplasts. The two enzymes appear unrelated in their derivation. Calcium ions play an essential role in preventing autodigestion of the excreted enzyme. Bacterial proteins are found outside the cell boundary as a consequence either of passive processes such as leakage or lysis or of active excretion. Under conditions in which leakage and lysis do not occur, as during exponential growth, the cell boundary is a barrier causing a complete separation of the bulk of the intracellular proteins from the one or very few extracellular proteins, with no trace of either type being detectable on the wrong side of the boundary. Since in bacteria there is no evidence of protein being produced other than internally, the separation into intraand extracellular proteins should occur after peptide chain formation. The question arises as to whether the structure of the cell boundary or that of the excreted proteins themselves determines this separation. Coccus P, a Sarcina closely related to Micrococcus lysodeikticus (3), produces an extracellular proteinase during the exponential phase of growth so that the process appears to be active excretion. The organism grows exponentially in a defined synthetic medium (12) to relatively high cell density (10{sup 9} cells/ml); therefore the mechanism of excretion can be studied over an extended period of time without the difficulties of changing growth rates. Coagulation of reconstituted skim milk provides a simple and sensitive assay for enzyme activity (I 1). The extracellular proteinase has also been purified and partially characterized (6-8). It has been shown

Purification and genetic characterisation of the novel bacteriocin LS2 produced by the human oral strain Lactobacillus salivarius BGHO1.

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Busarcevic, Milos; Dalgalarrondo, Michèle

2012-08-01

The aim of this study was to investigate the antimicrobial potential of Lactobacillus salivarius BGHO1, a human oral strain with probiotic characteristics and a broad inhibitory spectrum both against Gram-positive and Gram-negative pathogens. Here we present the bacteriocin LS2, an extremely pH- and heat-stable peptide with antilisterial activity. LS2 is a novel member of the class IId bacteriocins, unique among all currently characterised bacteriocins. It is somewhat similar to putative bacteriocins from several oral streptococci, including the cariogenic Streptococcus mutans. LS2 is a 41-amino-acid, highly hydrophobic cationic peptide of 4115.1Da that is sensitive to proteolytic enzymes. LS2 was purified from cells of strain BGHO1 by solvent extraction and reverse-phase chromatography. Mass spectrometry was used to determine the molecular mass of the purified peptide. N-terminal amino acid sequencing enabled identification of the LS2 structural gene bacls2 by a reverse genetics approach. Downstream of the bacls2 gene, two bacteriocin-like genes were found, named blp1a and blp1b, and one putative bacteriocin immunity gene named bimlp. We also present the identification of the 242-kb megaplasmid pMPHO1 by pulsed-field gel electrophoresis, which harbours the genes bacls2, blp1a, blp1b and bimlp. Two peptides with antimicrobial activity, whose approximate sizes corresponded to those of blp1a and blp1b, were identified only after culturing strain BGHO1 in a chemically defined medium. This study demonstrated the capacity of Lactobacillus salivarius BGHO1 to produce multiple bacteriocins and further established this strain as a promising probiotic candidate. Copyright © 2012 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

Variation in the strain anisotropy of Zircaloy with temperature and strain

International Nuclear Information System (INIS)

Hindle, E.D.; Worswick, D.

1984-01-01

The strong crystallographic texture which is developed during the fabrication of zirconium-based alloys causes pronounced anisotropy in their mechanical properties, particularly deformation. The tendency for circular-section tension specimens with a high concentration of basal poles in one direction to become elliptical when deformed in tension has been used in this study to provide quantitative data on the effects of both strain and temperature on strain anisotropy. Tension tests were carried out over a temperature range of 293 to 1193 K on specimens machined from Zircaloy-2 plate. The strain anisotropy was found to increase markedly at temperatures over 923 K, reaching a maximum in the region of 1070 K. The strain anisotropy increased with increasing strain in this temperature region. The study was extended to Zircaloy-4 pressurized-water reactor fuel cladding by carrying out tube swelling tests and evaluating the axial deformation produced. Although scatter in the test results was higher than that exhibited in the tension tests, the general trend in the data was similar. The effects of the strain anisotropy observed are discussed in relation to the effects of temperature on the ductility of Zircaloy fuel cladding tubes during postulated largebreak loss-of-coolant accidents

Strain-based HLA association analysis identified HLA-DRB1*09:01 associated with modern strain tuberculosis.

Science.gov (United States)

Toyo-Oka, L; Mahasirimongkol, S; Yanai, H; Mushiroda, T; Wattanapokayakit, S; Wichukchinda, N; Yamada, N; Smittipat, N; Juthayothin, T; Palittapongarnpim, P; Nedsuwan, S; Kantipong, P; Takahashi, A; Kubo, M; Sawanpanyalert, P; Tokunaga, K

2017-09-01

Tuberculosis (TB) occurs as a result of complex interactions between the host immune system and pathogen virulence factors. Human leukocyte antigen (HLA) class II molecules play an important role in the host immune system. However, no study has assessed the association between HLA class II genes and susceptibility to TB caused by specific strains. This study investigated the possible association of HLA class II genes with TB caused by modern and ancient Mycobacterium tuberculosis (MTB). The study included 682 patients with TB and 836 control subjects who were typed for HLA-DRB1 and HLA-DQB1 alleles. MTB strains were classified using a large sequence polymorphism typing method. Association analysis was performed using common HLA alleles and haplotypes in different MTB strains. HLA association analysis of patients infected with modern MTB strains showed significant association for HLA-DRB1*09:01 (odds ratio [OR] = 1.82; P-value = 9.88 × 10 -4 ) and HLA-DQB1*03:03 alleles (OR = 1.76; P-value = 1.31 × 10 -3 ) with susceptibility to TB. Haplotype analysis confirmed that these alleles were in strong linkage disequilibrium and did not exert an interactive effect. Thus, the results of this study showed an association between HLA class II genes and susceptibility to TB caused by modern MTB strains, suggesting the importance of strain-specific analysis to determine susceptibility genes associated with TB. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.