Putative bronchopulmonary flagellated protozoa in immunosuppressed patients.

Science.gov (United States)

Kilimcioglu, Ali Ahmet; Havlucu, Yavuz; Girginkardesler, Nogay; Celik, Pınar; Yereli, Kor; Özbilgin, Ahmet

2014-01-01

Flagellated protozoa that cause bronchopulmonary symptoms in humans are commonly neglected. These protozoal forms which were presumed to be "flagellated protozoa" have been previously identified in immunosuppressed patients in a number of studies, but have not been certainly classified so far. Since no human cases of bronchopulmonary flagellated protozoa were reported from Turkey, we aimed to investigate these putative protozoa in immunosuppressed patients who are particularly at risk of infectious diseases. Bronchoalveolar lavage fluid samples of 110 immunosuppressed adult patients who were admitted to the Department of Chest Diseases, Hafsa Sultan Hospital of Celal Bayar University, Manisa, Turkey, were examined in terms of parasites by light microscopy. Flagellated protozoal forms were detected in nine (8.2%) of 110 cases. Metronidazole (500 mg b.i.d. for 30 days) was given to all positive cases and a second bronchoscopy was performed at the end of the treatment, which revealed no parasites. In conclusion, immunosuppressed patients with bronchopulmonary symptoms should attentively be examined with regard to flagellated protozoa which can easily be misidentified as epithelial cells.

The toxicity of the fungicide Propiconazole to soil flagellates

DEFF Research Database (Denmark)

Ekelund, Flemming; Westergaard, Kamma; Søe, Dorthe

2000-01-01

We investigated the effects of the ergosterol-inhibiting fungicide, propiconazole {1-[[2-(2,4-dichlorphenyl) - 4 - propyl - 1,3 - dioxolan - 2 - yl]methyl] - 1H - 1,2,4 triazole; Tilt}, on mixed natural populations of bacterivorous and fungivorous flagellates in soil and on single species...... of bacterivorous flagellates in liquid culture. The fungicide affected a mixed natural population of fungivorous flagellates less than the population of bacterivorous flagellates. Our results indicated that the effects of propiconazole on flagellates are direct toxic effects and not effects mediated via their food....... All tested types of flagellates were significantly harmed when exposed to the concentration of propiconazole normally applied to agricultural fields (625¿mg l-1). However, when exposed to the concentration of propiconazole which we expect in the soil water phase after application (ca. 0.6¿mg l-1...

An analytical model of flagellate hydrodynamics

International Nuclear Information System (INIS)

Dölger, Julia; Bohr, Tomas; Andersen, Anders

2017-01-01

Flagellates are unicellular microswimmers that propel themselves using one or several beating flagella. We consider a hydrodynamic model of flagellates and explore the effect of flagellar arrangement and beat pattern on swimming kinematics and near-cell flow. The model is based on the analytical solution by Oseen for the low Reynolds number flow due to a point force outside a no-slip sphere. The no-slip sphere represents the cell and the point force a single flagellum. By superposition we are able to model a freely swimming flagellate with several flagella. For biflagellates with left–right symmetric flagellar arrangements we determine the swimming velocity, and we show that transversal forces due to the periodic movements of the flagella can promote swimming. For a model flagellate with both a longitudinal and a transversal flagellum we determine radius and pitch of the helical swimming trajectory. We find that the longitudinal flagellum is responsible for the average translational motion whereas the transversal flagellum governs the rotational motion. Finally, we show that the transversal flagellum can lead to strong feeding currents to localized capture sites on the cell surface. (paper)

Growth and flagellation of Vibrio fischeri during initiation of the sepiolid squid light organ symbiosis.

Science.gov (United States)

Ruby, E G; Asato, L M

1993-01-01

A pure culture of the luminous bacterium Vibrio fischeri is maintained in the light-emitting organ of the sepiolid squid Euprymna scolopes. When the juvenile squid emerges from its egg it is symbiont-free and, because bioluminescence is part of an anti-predatory behavior, therefore must obtain a bacterial inoculum from the surrounding environment. We document here the kinetics of the process by which newly hatched juvenile squids become infected by symbiosis-competent V. fischeri. When placed in seawater containing as few as 240 colony-forming-units (CFU) per ml, the juvenile became detectably bioluminescent within a few hours. Colonization of the nascent light organ was initiated with as few as 1 to 10 bacteria, which rapidly began to grow at an exponential rate until they reached a population size of approximately 10(5) cells by 12 h after the initial infection. Subsequently, the number of bacteria in the established symbiosis was maintained essentially constant by a combination of both a > 20-fold reduction in bacterial growth rate, and an expulsion of excess bacteria into the surrounding seawater. While V. fischeri cells are normally flagellated and motile, these bacteria did not elaborate these appendages once the symbiosis was established; however, they quickly began to synthesize flagella when they were removed from the light organ environment. Thus, two important biological characteristics, growth rate and flagellation, were modulated during establishment of the association, perhaps as part of a coordinated series of symbiotic responses.

A description of Apocarchesium rosettum n. gen., n. sp. and a redescription of Ophrydium eichornii Ehrenberg, 1838, two freshwater peritrichous ciliates from Japan.

Science.gov (United States)

Ji, Daode; Kusuoka, Yasushi

2009-01-01

This paper includes the proposal of a new genus for a new species of peritrichous ciliate, Apocarchesium rosettum n. gen., n. sp., as well as the first description by modern techniques of another peritrich, Ophrydium eichornii Ehrenberg, 1838. The genus Apocarchesium is separated from the related genus Carchesium by the appearance of the stalk and the arrangement of zooids, and diagnosed as follows: colonial vorticellid, with all zooids attached in rosette fashion to the tip of their common stalk, which is unbranched and contracts spirally; pellicle with parallel silverlines. The morphology, infraciliature, and silverline system of both species were investigated by observation in vivo and silver-staining methods.

Prey capture by freely swimming flagellates

Science.gov (United States)

Andersen, Anders; Dolger, Julia; Nielsen, Lasse Tor; Kiorboe, Thomas

2017-11-01

Flagellates are unicellular microswimmers that propel themselves using one or several beating flagella. Here, we explore the dependence of swimming kinematics and prey clearance rate on flagellar arrangement and determine optimal flagellar arrangements and essential trade-offs. To describe near-cell flows around freely swimming flagellates we consider a model in which the cell is represented by a no-slip sphere and each flagellum by a point force. For uniflagellates pulled by a single flagellum the model suggests that a long flagellum favors fast swimming, whereas high clearance rate is favored by a very short flagellum. For biflagellates with both a longitudinal and a transversal flagellum we explore the helical swimming kinematics and the prey capture sites. We compare our predictions with observations of swimming kinematics, prey capture, and flows around common marine flagellates. The Centre for Ocean Life is a VKR Centre of Excellence supported by the Villum Foundation.

Flagellate dermatitis following consumption of shiitake mushroom

Directory of Open Access Journals (Sweden)

Hui Voon Loo

2011-10-01

Full Text Available Japanese dermatologists were the first to describe the very characteristic flagellate dermatitis following consumption of under-cooked or raw shiitake mushroom (Lentinus edodes. These similar eruptions were also reported in patients treated with bleomycin, in dermatomyositis and adult onset Still’s disease. We report a case where a 40 year old chinese female developed flagellate dermatitis following ingestion of a bun containing shiitake mushroom.

Survival of marine heterotrophic flagellates isolated from the surface and the deep sea at high hydrostatic pressure: Literature review and own experiments

Science.gov (United States)

Živaljić, Suzana; Schoenle, Alexandra; Nitsche, Frank; Hohlfeld, Manon; Piechocki, Julia; Reif, Farina; Shumo, Marwa; Weiss, Alexandra; Werner, Jennifer; Witt, Madeleine; Voss, Janine; Arndt, Hartmut

2018-02-01

Although the abyssal seafloor represents the most common benthic environment on Earth, eukaryotic microbial life at abyssal depths is still an uncharted territory. This is in striking contrast to their potential importance regarding the material flux and bacteria consumption in the deep sea. Flagellate genotypes determined from sedimentary DNA deep-sea samples might originate from vital deep-sea populations or from cysts of organisms sedimented down from surface waters. The latter one may have never been active under deep-sea conditions. We wanted to analyze the principal ability of cultivable heterotrophic flagellates of different phylogenetic groups (choanoflagellates, ancyromonads, euglenids, kinetoplastids, bicosoecids, chrysomonads, and cercozoans) to survive exposure to high hydrostatic pressure (up to 670 bar). We summarized our own studies and the few available data from literature on pressure tolerances of flagellates isolated from different marine habitats. Our results demonstrated that many different flagellate species isolated from the surface waters and deep-sea sediments survived drastic changes in hydrostatic pressure. Barophilic behavior was also recorded for several species isolated from the deep sea indicating their possible genetic adaptation to high pressures. This is in accordance with records of heterotrophic flagellates present in environmental DNA surveys based on clone libraries established for deep-sea environments.

Bacteroidales ectosymbionts of gut flagellates shape the nitrogen-fixing community in dry-wood termites

Science.gov (United States)

Desai, Mahesh S; Brune, Andreas

2012-01-01

Although it is well documented that the lack of nitrogen in the diet of wood-feeding termites is compensated by the nitrogen-fixing capacity of their gut microbiota, the bacteria responsible for this activity are largely unknown. Here, we analyzed the diversity and expression of nitrogenase genes (homologs of nifH) in four species of dry-wood termites (Kalotermitidae), which thrive on a particularly nitrogen-poor resource. Although each species harbored a highly diverse suite of termite-specific homologs in their microliter-sized hindgut, only a core set related to nifH genes of Treponema and Azoarcus spp., ‘Azobacteroides pseudotrichonymphae', the first member of the Bacteroidales identified as a diazotroph, and termite-gut-specific anfH genes of hitherto unknown origin were preferentially expressed. Transcription patterns corroborated that the populations of active diazotrophs differ fundamentally between termite genera. Capillary-picked suspensions of the flagellates Devescovina arta and Snyderella tabogae revealed that their bacterial ectosymbionts each possess two paralogs of nifH, which apparently have been acquired consecutively during evolution of Bacteroidales, but only one of them (anfH) is actively expressed. Transcription patterns correlated neither with the molybdenum content of the diet nor with intestinal hydrogen concentrations, measured with microsensors. We propose that the nitrogen-fixing community in different dry-wood termites is shaped by the symbionts of their specific flagellate populations. Our findings suggest that the diazotrophic nature of ‘Armantifilum devescovinae' has an important role in the nitrogen metabolism of dry-wood termites and is the driving force of co-evolution with its flagellate host. PMID:22189498

Peritrich epibionts on the hadal isopod species Macrostylis marionae n. sp. from the Puerto Rico Trench used as indicator for sex-specific behaviour

Science.gov (United States)

Kniesz, Katharina; Brandt, Angelika; Riehl, Torben

2018-02-01

Macrostylis marionae n. sp. is described by means of integrative taxonomy. It is the second isopod species (Crustacea) described from the hadal Puerto Rico Trench. It differs from other Macrostylidae (Janiroidea) predominantly by the lack of the tergal borders between the fossosome segments. Adult males of M. marionae n. sp. differed from females and juveniles of both sexes in a higher number of peritrich ciliate epibionts. In total, 64.3% of adult males and only 10.5% of adult females were infested. Because macrostylids are generally considered infaunal, with a digging lifestyle, while peritrichs require aquatic medium for filter feeding, this observed pattern led to the hypothesis of a behavioural sexual dimorphism in this species of Macrostylidae. Accordingly, the epibionts may prefer adult male macrostylids as basibionts because of a rather epifaunal and roaming lifestyle. In contrast they may avoid females due to a stationary and infaunal behaviour. Additionally, the stage progression of the M. marionae male ontogeny was reconstructed.

Tolerance of soil flagellates to increased NaCl levels

DEFF Research Database (Denmark)

Ekelund, Flemming

2002-01-01

The ability of heterotrophic flagellates to survive and adapt to increasing salinities was investigated in this study. Whole soil samples were subjected to salinities corresponding to marine conditions and clonal cultures were used to perform growth and adaptation experiments at a wide range...... of different salinities (0-50 ppm). More morphotypes tolerant to elevated NaCl levels were found in road verge soil that was heavily exposed to de-icing salt than in less exposed soils, though there were fewer tolerant than intolerant morphotypes in all soils examined. Heterotrophic flagellates isolated...... on a freshwater medium from a non-exposed soil were unable to thrive at salinities above 15 ppt, and showed reduced growth rates even at low salt salinities (1-5 ppt). The findings suggest that heterotrophic soil flagellates are less tolerant to NaCl than their aquatic relatives, possibly due to their long...

Use of genetically marked minicells as a probe in measurement of predation on bacteria in aquatic environments

International Nuclear Information System (INIS)

Wikner, J.; Andersson, A.; Normark, S.; Hagstroem, A.

1986-01-01

Minicells produced by Escherichia coli M2141 were used as probes to measure predation on pelagic bacteria in situ. The minicells, labeled with [ 35 S]methionine in one specific protein, were shown to disappear in the presence of a microflagellate (Ochromonas sp.), as seen by a decrease in the amount of labeled marker protein with time. Incubation in filtered (pore size, 0.2 μm) and autoclaved seawater did not affect the amount of labeled marker protein in the minicell. The generation time of flagellates feeding on minicells was determined to be similar to that found for flagellates grown on seawater bacteria or living E. coli NC3. Data indicate that minicells are seen as true food particles by the flagellates. The minicell probe was used in recapture experiments, in which predation in situ on pelagic bacteria was demonstrated. The rate of bacterial production showed a clear covariation with the rate of predation, both in different sea areas and in depth profiles. The obtained results (11 field experiments) showed that the rate of predation, on average, accounts for the consumption of 62% of the bacteria produced

Shiitake Flagellate Dermatitis: the First Case Reported in Ireland

LENUS (Irish Health Repository)

Byrne, N

2017-01-01

Shiitake (Lentinula edodes) is the second most commonly consumed mushroom worldwide1. It is used in Asian medicine for its anticarcinogenic, antihypertensive and lipid lowering properties2. Furthermore, extracts of these mushrooms are used in over-the-counter dietary supplements designed to improve the immune system1. The first case of shiitake mushroom induced flagellate dermatitis was described in Japan in 1977 and it is now being reported in the western world3. After literary review and consultation with the Irish National Poisons Information Centre, we believe this is the first reported case of shiitake flagellate dermatitis in Ireland

Swimming, swarming, twitching, and chemotactic responses of Cupriavidus metallidurans CH34 and Pseudomonas putida mt2 in the presence of cadmium.

Science.gov (United States)

Shamim, Saba; Rehman, Abdul; Qazi, Mahmood Hussain

2014-04-01

To use of microorganisms for bioremediation purposes, the study of their motility behavior toward metals is essential. In the present study, Cupriavidus metallidurans CH34 and Pseudomonas putida mt2 were used as cadmium (Cd)-resistant and -sensitive bacteria, respectively, to evaluate the effects of Cd on their motility behaviors. Potassium morpholinopropane sulfonate (MOPS) buffer was used to observe the motility behavior of both isolates. Movement of mt2 was less in MOPS buffer compared with CH34, likely reflecting the mono-flagellated nature of mt2 and the peritrichous nature of CH34. The swimming, swarming, twitching, and chemotaxis behaviors of mt2 were greater in the presence of glucose than that of Cd. mt2 exhibited negative motility behaviors when exposed to Cd, but the opposite effect was seen in CH34. Cd was found to be a chemorepellent for mt2 but a chemoattractant for CH34, suggesting that CH34 is a potential candidate for metal (Cd) bioremediation.

Removal of bacteria from boar ejaculates by Single Layer Centrifugation can reduce the use of antibiotics in semen extenders.

Science.gov (United States)

Morrell, J M; Wallgren, M

2011-01-01

There is considerable interest world-wide in reducing the use of antibiotics to stem the development of antibiotic-resistant strains of bacteria. An alternative to the routine addition of antibiotics to semen extenders in livestock breeding would be to separate the spermatozoa from bacterial contaminants in the semen immediately after collection. The present study was designed to determine whether such separation was possible by Single Layer Centrifugation (SLC) using the colloid Androcoll™-P. The results showed that complete removal (6 out of 10 samples), or considerable reduction of bacterial contaminants (4 out of 10 samples) was possible with this method. The type of bacteria and/or the length of time between collection and SLC-processing affected the removal of bacteria, with motile flagellated bacteria being more likely to be present after SLC than non-flagellated bacteria. Although further studies are necessary, these preliminary results suggest that the use of SLC when processing boar semen for AI doses might enable antibiotic usage in semen extenders to be reduced. Copyright © 2010 Elsevier B.V. All rights reserved.

Katabia gromovi nov. gen., nov sp. - a new soil flagellate with affinities to Heteromita (Cercomonadida)

DEFF Research Database (Denmark)

Karpov, S.A.; Ekelund, Flemming; Moestrup, Øjvind

2003-01-01

Katabia gromovi, cercomonads, ultrastructure, cytoskeleton, soil flagellates, partial SSU gene sequence......Katabia gromovi, cercomonads, ultrastructure, cytoskeleton, soil flagellates, partial SSU gene sequence...

CHANGES IN THE MORPHOLOGY AND POLYSACCHARIDE CONTENT OF MICROCYSTIS AERUGINOSA (CYANOBACTERIA) DURING FLAGELLATE GRAZING(1).

Science.gov (United States)

Yang, Zhou; Kong, Fanxiang; Shi, Xiaoli; Zhang, Min; Xing, Peng; Cao, Huansheng

2008-06-01

To investigate the changes in the morphology and polysaccharide content of Microcystis aeruginosa (Kütz.) Kütz. during flagellate grazing, cultures of M. aeruginosa were exposed to grazing Ochromonas sp. for a period of 9 d under controlled laboratory conditions. M. aeruginosa responded actively to flagellate grazing and formed colonies, most of which were made up of several or dozens of cells, suggesting that flagellate grazing may be one of the biotic factors responsible for colony formation in M. aeruginosa. When colonies were formed, the cell surface ultrastructure changed, and the polysaccharide layer on the surface of the cell wall became thicker. This change indicated that synthesis and secretion of extracellular polysaccharide (EPS) of M. aeruginosa cells increased under flagellate grazing pressure. The contents of soluble extracellular polysaccharide (sEPS), bound extracellular polysaccharide (bEPS), and total polysaccharide (TPS) in colonial cells of M. aeruginosa increased significantly compared with those in single cells. This finding suggested that the increased amount of EPS on the cell surface may play a role in keeping M. aeruginosa cells together to form colonies. © 2008 Phycological Society of America.

Microcystins do not provide anti-herbivore defence against mixotrophic flagellates

NARCIS (Netherlands)

Wilken, S.; Wiezer, S.M.H.; Huisman, J.; Van Donk, E.

2010-01-01

While most experiments investigating zooplankton grazing on harmful cyanobacteria have been carried out with metazoan plankton, several protozoa can also feed efficiently on cyanobacteria. We investigated grazing by the mixotrophic flagellate Ochromonas sp. on the toxic cyanobacterium Microcystis

Biomanufacturing and self-propulsion dynamics of nanoscale bacteria-enabled autonomous delivery systems

Energy Technology Data Exchange (ETDEWEB)

Traore, Mahama A.; Behkam, Bahareh, E-mail: behkam@vt.edu [Mechanical Engineering Department, Virginia Tech, Blacksburg, Virginia 24061 (United States); School of Biomedical Engineering and Sciences, Virginia Tech, Blacksburg, Virginia 24061 (United States); Damico, Carmen M. [Mechanical Engineering Department, Virginia Tech, Blacksburg, Virginia 24061 (United States)

2014-10-27

Flagellated bacteria have superb self-propulsion capabilities and are able to effectively move through highly viscous fluid and semi-solid (porous) environments. This innate aptitude has been harvested for whole-cell actuation of bio-hybrid microrobotic systems with applications in directed transport and microassembly. In this work, we present the biomanufacturing of Nanoscale Bacteria-Enabled Autonomous Delivery Systems (NanoBEADS) by controlled self-assembly and investigate the role of nanoparticle load on the dynamics of their self-propulsion in aqueous environments. Each NanoBEADS agent is comprised of spherical polystyrene nanoparticles assembled onto the body of a flagellated Escherichia coli bacterium. We demonstrate that the NanoBEADS assembly configuration is strongly dependent upon the nanoparticles to bacteria ratio. Furthermore, we characterized the stochastic motion of the NanoBEADS as a function of the quantity and size of the nanoparticle load and computationally analyzed the effect of the nanoparticle load on the experienced drag force. We report that the average NanoBEADS swimming speed is reduced to 65% of the free-swimming bacteria speed (31 μm/s) at the highest possible load. NanoBEADS can be utilized as single agents or in a collaborative swarm in order to carry out specific tasks in a wide range of applications ranging from drug delivery to whole cell biosensing.

Laminar flow assisted anisotropic bacteria absorption for chemotaxis delivery of bacteria-attached microparticle

Science.gov (United States)

Huh, Keon; Oh, Darong; Son, Seok Young; Yoo, Hyung Jung; Song, Byeonghwa; Cho, Dong-il Dan; Seo, Jong-Mo; Kim, Sung Jae

2016-12-01

The concepts of microrobots has been drawn significant attentions recently since its unprecedented applicability in nanotechnology and biomedical field. Bacteria attached microparticles presented in this work are one of pioneering microrobot technology for self-propulsion or producing kinetic energy from ambient for their motions. Microfluidic device, especially utilizing laminar flow characteristics, were employed for anisotropic attachment of Salmonella typhimurium flagellated chemotactic bacteria to 30 um × 30 um and 50 um × 50 um microparticles that made of biodegradable polymer. Any toxic chemicals or harmful treatments were excluded during the attachment process and it finished within 100 s for the anisotropic attachment. The attachments were directly confirmed by fluorescent intensity changes and SEM visualization. Chemotaxis motions were tracked using aspartate and the maximum velocity of the bacteria-attached microrobot was measured to be 5 um/s which is comparable to prior state of art technologies. This reusable and scalable method could play a key role in chemotaxis delivery of functional microparticles such as drug delivery system.

Some heterotrophic flagellates from a cultivated garden soil in Australia

DEFF Research Database (Denmark)

Ekelund, Flemming; Patterson, DJ

1997-01-01

The flagellates of an Australian garden soil were studied by placing coverslips on wet soil and subsequently examining the coverslips by light microscopy. A number of genera and species were found which have not previously been reported from soil samples. Besides the three new species, Apusomonas...

Flagellated Magnetotactic Bacteria as Controlled MRI-trackable Propulsion and Steering Systems for Medical Nanorobots Operating in the Human Microvasculature.

Science.gov (United States)

Martel, Sylvain; Mohammadi, Mahmood; Felfoul, Ouajdi; Lu, Zhao; Pouponneau, Pierre

2009-04-01

Although nanorobots may play critical roles for many applications in the human body such as targeting tumoral lesions for therapeutic purposes, miniaturization of the power source with an effective onboard controllable propulsion and steering system have prevented the implementation of such mobile robots. Here, we show that the flagellated nanomotors combined with the nanometer-sized magnetosomes of a single Magnetotactic Bacterium (MTB) can be used as an effective integrated propulsion and steering system for devices such as nanorobots designed for targeting locations only accessible through the smallest capillaries in humans while being visible for tracking and monitoring purposes using modern medical imaging modalities such as Magnetic Resonance Imaging (MRI). Through directional and magnetic field intensities, the displacement speeds, directions, and behaviors of swarms of these bacterial actuators can be controlled from an external computer.

The Hidden Diversity of Flagellated Protists in Soil.

Science.gov (United States)

Venter, Paul Christiaan; Nitsche, Frank; Arndt, Hartmut

2018-07-01

Protists are among the most diverse and abundant eukaryotes in soil. However, gaps between described and sequenced protist morphospecies still present a pending problem when surveying environmental samples for known species using molecular methods. The number of sequences in the molecular PR 2 database (∼130,000) is limited compared to the species richness expected (>1 million protist species) - limiting the recovery rate. This is important, since high throughput sequencing (HTS) methods are used to find associative patterns between functional traits, taxa and environmental parameters. We performed HTS to survey soil flagellates in 150 grasslands of central Europe, and tested the recovery rate of ten previously isolated and cultivated cercomonad species, among locally found diversity. We recovered sequences for reference soil flagellate species, but also a great number of their phylogenetically evaluated genetic variants, among rare and dominant taxa with presumably own biogeography. This was recorded among dominant (cercozoans, Sandona), rare (apusozoans) and a large hidden diversity of predominantly aquatic protists in soil (choanoflagellates, bicosoecids) often forming novel clades associated with uncultured environmental sequences. Evaluating the reads, instead of the OTUs that individual reads are usually clustered into, we discovered that much of this hidden diversity may be lost due to clustering. Copyright © 2018 Elsevier GmbH. All rights reserved.

Numerical Simulations Of Flagellated Micro-Swimmers

Science.gov (United States)

Rorai, Cecilia; Markesteijn, Anton; Zaitstev, Mihail; Karabasov, Sergey

2017-11-01

We study flagellated microswimmers locomotion by representing the entire swimmer body. We discuss and contrast the accuracy and computational cost of different numerical approaches including the Resistive Force Theory, the Regularized Stokeslet Method and the Finite Element Method. We focus on how the accuracy of the methods in reproducing the swimming trajectories, velocities and flow field, compares to the sensitivity of these quantities to certain physical parameters, such as the body shape and the location of the center of mass. We discuss the opportunity and physical relevance of retaining inertia in our models. Finally, we present some preliminary results toward collective motion simulations. Marie Skodowska-Curie Individual Fellowship.

Morphological and molecular identification of Tetratrichomonas flagellates from the giant anteater (Myrmecophaga tridactyla).

Science.gov (United States)

Ibañez-Escribano, A; Nogal-Ruiz, J J; Delclaux, M; Martinez-Nevado, E; Ponce-Gordo, F

2013-08-01

A tetratrichomonad flagellate found in the diarrhoeic faeces of a 5 years-old male giant anteater (Myrmecophaga tridactyla) was characterised by morphological and genetic analysis. This protozoan presents four anterior flagella of unequal length and a recurrent flagellum attached to the undulating membrane without a free end portion, and a broad axostyle projection. Numerous vacuoles of different sizes containing bacteria and digestion products were found. The complete sequence of the DNA coding for the 16S rRNA-ITS1-5.8S rRNA-ITS2 region was also obtained in order to compare this isolate with other tetratrichomonad species. The sequence obtained was identical to others previously obtained by other researchers from bovines and turtles (Geochelone sp.). It is not easily explainable how the same organism could be found in such different hosts and locations; however these results indicate that some tetratrichomonad species could have a wide host range and could survive in a wide range of environmental conditions. Copyright © 2013 Elsevier Ltd. All rights reserved.

A study of the soil flagellate Phalansterium solitarium Sandon 1924 with preliminary data on its ultrastructure

DEFF Research Database (Denmark)

Ekelund, Flemming

2002-01-01

Phalansterium solitarium Sandon 1924, a common soil flagellate, was isolated and a Sandon 1924, a common soil flagellate, was isolated and a clonal culture was examined using light and electron microscopy. The first preliminary observations of its ultrastructure show that the cells of Ph....... solitarium have the same main characters as an earlier investigated species of the genus, Ph. digitatum Stein 1878, including a collarlike structure surrounding the basis of the single emerging flagellum, tubular cristae, a single basal body, surrounded by x, y and z zones with radiating microtubules...

Rumen bacteria

International Nuclear Information System (INIS)

McSweeney, C.S.; Denman, S.E.; Mackie, R.I.

2005-01-01

The rumen is the most extensively studied gut community and is characterized by its high population density, wide diversity and complexity of interactions. This complex, mixed microbial culture is comprised of prokaryote organisms including methane-producing archaebacteria, eukaryote organisms, such as ciliate and flagellate protozoa, anaerobic phycomycete fungi and bacteriophage. Bacteria are predominant (up to 10 11 viable cells per g comprising 200 species) but a variety of ciliate protozoa occur widely (10 4 -10 6 /g distributed over 25 genera). The anaerobic fungi are also widely distributed (zoospore population densities of 10 2 -10 4 /g distributed over 5 genera). The occurrence of bacteriophage is well documented (10 7 -10 9 particles/g). This section focuses primarily on the widely used methods for the cultivation and the enumeration of rumen microbes, especially bacteria, which grow under anaerobic conditions. Methods that can be used to measure hydrolytic enzymes (cellulases, xylanases, amylases and proteinases) are also described, along with cell harvesting and fractionation procedures. Brief reference is also made to fungi and protozoa, but detailed explanations for culturing and enumerating these microbes is presented in Chapters 2.4 and 2.5

Swimming Motility Mediates the Formation of Neutrophil Extracellular Traps Induced by Flagellated Pseudomonas aeruginosa.

Directory of Open Access Journals (Sweden)

Madison Floyd

2016-11-01

Full Text Available Pseudomonas aeruginosa is an opportunistic pathogen causing severe infections often characterized by robust neutrophilic infiltration. Neutrophils provide the first line of defense against P. aeruginosa. Aside from their defense conferred by phagocytic activity, neutrophils also release neutrophil extracellular traps (NETs to immobilize bacteria. Although NET formation is an important antimicrobial process, the details of its mechanism are largely unknown. The identity of the main components of P. aeruginosa responsible for triggering NET formation is unclear. In this study, our focus was to identify the main bacterial factors mediating NET formation and to gain insight into the underlying mechanism. We found that P. aeruginosa in its exponential growth phase promoted strong NET formation in human neutrophils while its NET-inducing ability dramatically decreased at later stages of bacterial growth. We identified the flagellum as the primary component of P. aeruginosa responsible for inducing NET extrusion as flagellum-deficient bacteria remained seriously impaired in triggering NET formation. Purified P. aeruginosa flagellin, the monomeric component of the flagellum, does not stimulate NET formation in human neutrophils. P. aeruginosa-induced NET formation is independent of the flagellum-sensing receptors TLR5 and NLRC4 in both human and mouse neutrophils. Interestingly, we found that flagellar motility, not flagellum binding to neutrophils per se, mediates NET release induced by flagellated bacteria. Immotile, flagellar motor-deficient bacterial strains producing paralyzed flagella did not induce NET formation. Forced contact between immotile P. aeruginosa and neutrophils restored their NET-inducing ability. Both the motAB and motCD genetic loci encoding flagellar motor genes contribute to maximal NET release; however the motCD genes play a more important role. Phagocytosis of P. aeruginosa and superoxide production by neutrophils were also

Diplomonad flagellates of some ornamental fish cultured in Thailand

Directory of Open Access Journals (Sweden)

Boonkob Viriyapongsutee

2012-11-01

Full Text Available The study on diplomonad flagellates infection in some ornamental fishes in the family cichlidae i.e., angelfish(Pterophyllum scalare, oscar (Astronotus ocellatus, blue mbuna (Labeotropheus fuelleborni and the family osphronemidaei.e., Siamese fighting fish (Betta splendens revealed that this parasite infected three out of four ornamental fish species,angelfish, oscar and blue mbuna. The highest infection was recorded in angelfish (90% followed by oscar (75.4% and bluembuna (61%, respectively. Identification of diplomonad flagellates from angelfish by means of morphological studies underlight and electron microscopes indicated that the parasite was Spironucleus vortens. The 14–days LD50 of S. vortens inangelfish was 2.99x103 cells. Histopathological changes of infected angelfish revealed granulomatous liver, numerousnumbers of melanomacrophage in the spleen and inflammation of the intestine. Susceptibility study of S. vortens to goldfish(Carassius auratus, guppy (Poecilia reticulata and platy (Xiphophorus maculatus indicated that they were resistant toartificial infection. In vitro examination of the growth inhibition assay of S. vortens indicated that dimetridazole and metronidazolewere effective in inhibiting parasite growth after 48 hrs exposure at concentrations of >4.0 μg/ml and >6.0 μg/ml,respectively. Magnesium sulfate at a concentration of >60 mg/ml inhibited the parasite growth after 72 hrs exposure. In vivoexamination of the dimetridazole efficiency on S. vortens infection indicated that dimetridazole at 4.0 μg/ml provided thehighest efficiency which could be used for treatment of spironucleosis in angelfish.

Interactions between the intestinal flagellates Giardia muris and Spironucleus muris and the blood parasites Babesia microti, Plasmodium yoelii and Plasmodium berghei in mice.

Science.gov (United States)

Brett, S J; Cox, F E

1982-08-01

In mice infected with the intestinal flagellates Giardia muris or Spironucleus muris, together with the blood parasites Babesia microti or Plasmodium yoelii, there is a temporary decrease of flagellate cyst output coincident with the peak of the blood parasite infections, followed by a rapid return to normal levels. This decrease in cyst output is correlated with decreased numbers of trophozoites in the small intestine. The effect on S. muris is more marked than that on G. muris. Neither blood parasites has any effect on the total duration of the flagellate infection and the flagellates do not affect the blood parasites. In mice infected with G. muris or S. muris and P. berghei there is also a decrease in cyst output but this is less apparent than in infections with B. microti or P. yoelii because of the fatal nature of the P. berghei infection. It is suggested that the decrease in cyst output is probably due to changes in the contents of the small intestine or to non-specific immunological factors rather than to specific immunological changes.

Heavy metal toxicity and bioavailability of dissolved nutrients to a bacterivorous flagellate are linked to suspended particle physical properties

International Nuclear Information System (INIS)

Boenigk, Jens; Wiedlroither, Anneliese; Pfandl, Karin

2005-01-01

Many dissolved substances attach easily to sediment particles. In the presence of suspended sediments bioavailability of dissolved substances is therefore, usually reduced and clays are even applied to 'wash' natural waters upon pollution. In organisms which feed on food organisms in the size range of these suspended sediment particles, however, bioavailability of such substances may even increase. For microorganisms the interaction with dissolved substances and suspended sediment particles so far has hardly been investigated. We specifically tested: (1) the importance of suspended particles as an uptake route for dissolved substances; and (2) the significance of particle surface properties, i.e. surface load and mineralogy. As a model system we used an axenically cultured strain of a widespread and often abundant flagellate ('Spumella-like' flagellate strain JBM10). We tested the toxicity of cadmium (II) and mercury (II) as well as availability of dissolved organic matter (DOM) in the absence as well as in the presence of different natural clays, i.e. a kaolinite, a montmorillonite, and a mixed clay, and of artificial silicate particles of different surface charge. When applied separately the presence of the heavy metals cadmium and mercury as well as of suspended particles negatively affected the investigated flagellate but nutritive organics supported growth of the investigated flagellate. Toxic stress response comprises behavioral changes including enhanced swimming activity and stress egestion of ingested particles and was generally similar for a variety of different flagellate species. In combination with suspended particles, the respective effect of trace metals and nutritive substances decreased. Regarding the particle quality, cadmium toxicity increased with increasingly negative surface charge, i.e. increasing surface density of silanol groups (Pearson's product moment, P = 0.005). For mercury particle mineralogy still had a significant effect (P < 0

Bacteria exploit a polymorphic instability of the flagellar filament to escape from traps.

Science.gov (United States)

Kühn, Marco J; Schmidt, Felix K; Eckhardt, Bruno; Thormann, Kai M

2017-06-13

Many bacterial species swim by rotating single polar helical flagella. Depending on the direction of rotation, they can swim forward or backward and change directions to move along chemical gradients but also to navigate their obstructed natural environment in soils, sediments, or mucus. When they get stuck, they naturally try to back out, but they can also resort to a radically different flagellar mode, which we discovered here. Using high-speed microscopy, we monitored the swimming behavior of the monopolarly flagellated species Shewanella putrefaciens with fluorescently labeled flagellar filaments at an agarose-glass interface. We show that, when a cell gets stuck, the polar flagellar filament executes a polymorphic change into a spiral-like form that wraps around the cell body in a spiral-like fashion and enables the cell to escape by a screw-like backward motion. Microscopy and modeling suggest that this propagation mode is triggered by an instability of the flagellum under reversal of the rotation and the applied torque. The switch is reversible and bacteria that have escaped the trap can return to their normal swimming mode by another reversal of motor direction. The screw-type flagellar arrangement enables a unique mode of propagation and, given the large number of polarly flagellated bacteria, we expect it to be a common and widespread escape or motility mode in complex and structured environments.

New bacteria suitable for production of ethanol from maltose. Marutosu kara no etanoru seizo ni tekishita shinki saikin

Energy Technology Data Exchange (ETDEWEB)

Okamoto, T.; Taguchi, H.; Nakamura, K. (Kirin Brewery Co. Ltd., Tokyo (Japan))

1992-10-07

Bacteria such as Zymomonas atracts attention in production of ethanol from carbohydrates in addition to yeast used for a long time, however, Zymomonas ferments only glucose, fructose and sucrose. After searching microbes in the nature with excellent properties in fermentation ability and salt resistance, a new Gram-negative bacterium has been isolated from a certain tree sap which is suitable for production of ethanol from maltose and starch hydrolyzate. The features of cell morphology of the new bacterium are: bacillus, peritrichous, no sport forming, Q-9 in quinone system, and an anaerobic Gram-negative bacterium. It utilizes maltose, sorbitol and maltose and produces [alpha]-glucosidas but no [beta]-galactosidase nor arginine dihydrase. The strain T109 is deposited as FERM BP-3292 to the Industrial Research Institute of Microbiology. 2 figs., 2 tabs.

Combined effects of the herbicide terbuthylazine and temperature on different flagellates from the Northern Adriatic Sea.

Science.gov (United States)

Fiori, Emanuela; Mazzotti, Matilde; Guerrini, Franca; Pistocchi, Rossella

2013-03-15

The triazinic herbicide terbuthylazine (TBA) is becoming an emergent contaminant in Italian rivers and in coastal and groundwater. A preliminary analysis of the sensitivity of marine flagellates to TBA was performed by monitoring the photosynthetic efficiency of nine species (belonging to the Dinophyceae or Raphidophyceae class) isolated from the Adriatic Sea. Different sensitivity levels for each flagellate were observed and the most sensitive microalgae, based on PSII inhibition, were: Gonyaulax spinifera>Fibrocapsa japonica>Lingulodinium polyedrum while the most resistant were two species belonging to the Prorocentrum genus. Then the response of two microalgae to drivers, such as temperature and terbuthylazine, applied in combination was also investigated. Two potentially toxic flagellates, Prorocentrum minimum and G. spinifera, were exposed, under different temperature conditions (15, 20 and 25°C), to TBA concentrations that did not completely affect PSII. For both flagellates, effects of TBA on algal growth, measured through cell density and carbon analysis, as well as on the photosynthetic activity are reported. All parameters analyzed showed a negative effect of TBA from the exponential phase. TBA effect on algal growth was significantly enhanced at the optimal temperature conditions (20 and 25°C), while no difference between control and herbicide treatments were detected for G. spinifera grown at 15°C, which represented a stress condition for this species. The maximum inhibition of photosynthetic efficiency was found at 20°C for both organisms. Both flagellates increased cell carbon and nitrogen content in herbicide treatments compared to the control, except G. spinifera grown at 15°C. Chlorophyll-a production was increased only in G. spinifera exposed to 5 μg L(-1) of TBA and the effect was enhanced with the increase of temperature. Herbicide-induced variations in cellular components determined changes in cellular carbon:nitrogen (C:N) and

Single bacteria movement tracking by online microscopy--a proof of concept study.

Directory of Open Access Journals (Sweden)

Andreas Ziegler

Full Text Available In this technical report we demonstrate a low-cost online unit allowing movement tracking of flagellated bacteria on a single-cell level during fermentation processes. The system's ability to distinguish different metabolic states (viability of bacteria by movement velocity was investigated. A flow-through cuvette with automatically adjustable layer thickness was developed. The cuvette can be used with most commercially available laboratory microscopes equipped with 40× amplification and a digital camera. In addition, an automated sample preparation unit and a software module was developed measuring size, moved distance, and speed of bacteria. In a proof of principle study the movement velocities of Bacillus amyloliquefaciens FZB42 during three batch fermentation processes were investigated. In this process the bacteria went through different metabolic states, vegetative growth, diauxic shift, vegetative growth after diauxic shift, and sporulation. It was shown that the movement velocities during the different metabolic states significantly differ from each other. Therefore, the described setup has the potential to be used as a bacteria viability monitoring tool. In contrast to some other techniques, such as electro-optical techniques, this method can even be used in turbid production media.

Symbiotic flagellate protists as cryptic drivers of adaptation and invasiveness of the subterranean termite Reticulitermes grassei Clément.

Science.gov (United States)

Duarte, Sónia; Nobre, Tânia; Borges, Paulo A V; Nunes, Lina

2018-06-01

Changes in flagellate protist communities of subterranean termite Reticulitermes grassei across different locations were evaluated following four predictions: (i) Rural endemic (Portugal mainland) termite populations will exhibit high diversity of symbionts; (ii) invasive urban populations (Horta city, Faial island, Azores), on the contrary, will exhibit lower diversity of symbionts, showing high similarity of symbiont assemblages through environmental filtering; (iii) recent historical colonization of isolated regions-as the case of islands-will imply a loss of symbiont diversity; and (iv) island isolation will trigger a change in colony breeding structure toward a less aggressive behavior. Symbiont flagellate protist communities were morphologically identified, and species richness and relative abundances, as well as biodiversity indices, were used to compare symbiotic communities in colonies from urban and rural environments and between island invasive and mainland endemic populations. To evaluate prediction on the impact of isolation (iv), aggression tests were performed among termites comprising island invasive and mainland endemic populations. A core group of flagellates and secondary facultative symbionts was identified. Termites from rural environments showed, in the majority of observed colonies, more diverse and abundant protist communities, probably confirming prediction (i). Corroborating prediction (ii), the two least diverse communities belong to termites captured inside urban areas. The Azorean invasive termite colonies had more diverse protist communities than expected and prediction (iii) which was not verified within this study. Termites from mainland populations showed a high level of aggressiveness between neighboring colonies, in contrast to the invasive colonies from Horta city, which were not aggressive to neighbors according to prediction (iv). The symbiotic flagellate community of R. grassei showed the ability to change in a way that might

Bacteria are not too small for spatial sensing of chemical gradients: An experimental evidence

DEFF Research Database (Denmark)

Thar, Roland; Kühl, Michael

2003-01-01

By analyzing the chemotactic behavior of a recently described marine bacterial species, we provide experimental evidence that bacteria are not too small for sensing chemical gradients spatially. The bipolar flagellated vibrioid bacteria (typical size 2 × 6 µm) exhibit a unique motility pattern...... as they translate along as well as rotate around their short axis, i.e., the pathways of the cell poles describe a double helix. The natural habitat of the bacteria is characterized by steep oxygen gradients where they accumulate in a band at their preferred oxygen concentration of ˜2 µM. Single cells leaving...... the band toward the oxic region typically return to the band within 16 s following a U-shaped track. A detailed analysis of the tracks reveals that the cells must be able to sense the oxygen gradient perpendicular to their swimming direction. Thus, they can detect oxygen gradients along a distance of ˜5 µm...

Transfer of seston lipids during a flagellate bloom from the surface to the benthic community in the Weddell Sea

Directory of Open Access Journals (Sweden)

Sergio Rossi

2013-09-01

Full Text Available Total lipid and fatty acid concentrations were studied in a late spring-early summer flagellate-dominated bloom in the Weddell Sea. These indicators were considered a good tool for assessing the quality of organic matter settling from surface to deep-water layers (epibenthic water layers. The results showed different patterns between the early (11-15 December 2003 and the late sampling period (18-27 December 2003 at all studied depths (5 m, 50 m and near-bottom water layers. Low phytoplankton biomass (mainly flagellates in the first half of the study corresponded to low total lipid and fatty acid concentrations. In the second sampling period a spring bloom (mainly flagellates and diatoms was detected, increasing the total lipid and fatty acid concentrations in the water column. The amount of settling organic matter from surface waters to the near-bottom water layers was high, especially in the late sampling period. Trophic markers showed evidence of a sink of available organic matter rich in quality and quantity, especially in terms of polyunsaturated fatty acids, for benthic organisms from surface layers to bottom layers in only a few days. The importance of studying short-time cycles in order to detect organic matter availability for benthic biota in view of the pulse-like dynamics of primary production in Antarctic waters is discussed.

[Eye witnesses and the flagellants in the year 1349].

Science.gov (United States)

Jansen-Sieben, R

1999-01-01

Deeply affected and often desperately afraid, many contemporaries recorded their observations and emotions. These reports--no matter how obviously subjective they sometimes were--provide valuable information about what happened during the plague pandemic of 1348-1350. Thus many of our fellow countrymen left behind a direct testimony: Bartholomew of Bruges, a canon in Andenne; Gilles li Muisis, the abbot of Saint Martin in Tournai; Ludovicus Sanctus of Beringen; Simon de Couvin, a canon in Liège; Jan van Boendale, an alderman's clerk in Antwerp; John of Burgundy (also known as John of Mandeville), professor of medicine in Liège; but also texts in Middle Dutch that were not known up to now, and therefore not published, such as the important thesis by Arent Schryver, licentiate in medicine (see next article); an account in verse in the Brabant Chronicle, as well as contemporary testimonies in a different language that have been translated into our language, such as that by John of Eschinden, Johannes de Rupescissa or Guy de Chauliac (who had had the plague himself). They describe the precautions, the causes (God, a comet, an eclipse of the sun, the polluted water, the planets, the air), the symptoms, the social groups most likely to be affected (the youth, the lower classes, the clergy), the high mortality, the problems of hygiene,the social and administrative chaos, the general panic, the flight of countless people. One of the most virulent reactions led to the emergence of the flagellant sect. They originated from Hungary and advanced in an unstoppable advance with a growing number of followers as far as our country, singing, praying, dancing and flaying themselves until they drew blood. We only recently discovered what they sang in Dutch: very recently, a unique roll of parchment was discovered that they carried in their processions, and that contains the text of their songs and a flagellant sermon. The existence of this valuable document and its contents are

Evaluation of Zosteric Acid for Mitigating Biofilm Formation of Pseudomonas putida Isolated from a Membrane Bioreactor System

Directory of Open Access Journals (Sweden)

Andrea Polo

2014-05-01

Full Text Available This study provides data to define an efficient biocide-free strategy based on zosteric acid to counteract biofilm formation on the membranes of submerged bioreactor system plants. 16S rRNA gene phylogenetic analysis showed that gammaproteobacteria was the prevalent taxa on fouled membranes of an Italian wastewater plant. Pseudomonas was the prevalent genus among the cultivable membrane-fouler bacteria and Pseudomonas putida was selected as the target microorganism to test the efficacy of the antifoulant. Zosteric acid was not a source of carbon and energy for P. putida cells and, at 200 mg/L, it caused a reduction of bacterial coverage by 80%. Biofilm experiments confirmed the compound caused a significant decrease in biomass (−97% and thickness (−50%, and it induced a migration activity of the peritrichous flagellated P. putida over the polycarbonate surface not amenable to a biofilm phenotype. The low octanol-water partitioning coefficient and the high water solubility suggested a low bioaccumulation potential and the water compartment as its main environmental recipient and capacitor. Preliminary ecotoxicological tests did not highlight direct toxicity effects toward Daphnia magna. For green algae Pseudokirchneriella subcapitata an effect was observed at concentrations above 100 mg/L with a significant growth of protozoa that may be connected to a concurrent algal growth inhibition.

A population of giant tailed virus-like particles associated with heterotrophic flagellates in a lake-type reservoir

Czech Academy of Sciences Publication Activity Database

Weinbauer, M.G.; Dolan, J. R.; Šimek, Karel

2015-01-01

Roč. 76, č. 2 (2015), s. 111-116 ISSN 0948-3055 R&D Projects: GA ČR(CZ) GA13-00243S Institutional support: RVO:60077344 Keywords : viral infection * virus induced mortality * burst size * heterotrophic flagellates Subject RIV: EE - Microbiology, Virology Impact factor: 2.109, year: 2015

Numerical Analysis of Small Deformation of Flexible Helical Flagellum of Swimming Bacteria

Science.gov (United States)

Takano, Yasunari; Goto, Tomonobu

Formulations are conducted to numerically analyze the effect of flexible flagellum of swimming bacteria. In the present model, a single-flagellate bacterium is assumed to consist of a rigid cell body of the prolate spheroidal shape and a flexible flagellum of the helical form. The resistive force theory is applied to estimate the force exerted on the flagellum. The torsional as well as the bending moments determine the curvature and the torsion of the deformed flagellum according to the Kirchhoff model for an elastic rod. The unit tangential vector along the deformed flagellum is calculated by applying evolution equations for space curves, and also a deformed shape of the flagellum is obtained.

EST analysis of the scaly green flagellate Mesostigma viride (Streptophyta: Implications for the evolution of green plants (Viridiplantae

Directory of Open Access Journals (Sweden)

Melkonian Michael

2006-02-01

Full Text Available Abstract Background The Viridiplantae (land plants and green algae consist of two monophyletic lineages, the Chlorophyta and the Streptophyta. The Streptophyta include all embryophytes and a small but diverse group of freshwater algae traditionally known as the Charophyceae (e.g. Charales, Coleochaete and the Zygnematales. The only flagellate currently included in the Streptophyta is Mesostigma viride Lauterborn. To gain insight into the genome evolution in streptophytes, we have sequenced 10,395 ESTs from Mesostigma representing 3,300 independent contigs and compared the ESTs of Mesostigma with available plant genomes (Arabidopsis, Oryza, Chlamydomonas, with ESTs from the bryophyte Physcomitrella, the genome of the rhodophyte Cyanidioschyzon, the ESTs from the rhodophyte Porphyra, and the genome of the diatom Thalassiosira. Results The number of expressed genes shared by Mesostigma with the embryophytes (90.3 % of the expressed genes showing similarity to known proteins is higher than with Chlamydomonas (76.1 %. In general, cytosolic metabolic pathways, and proteins involved in vesicular transport, transcription, regulation, DNA-structure and replication, cell cycle control, and RNA-metabolism are more conserved between Mesostigma and the embryophytes than between Mesostigma and Chlamydomonas. However, plastidic and mitochondrial metabolic pathways, cytoskeletal proteins and proteins involved in protein folding are more conserved between Mesostigma and Chlamydomonas than between Mesostigma and the embryophytes. Conclusion Our EST-analysis of Mesostigma supports the notion that this organism should be a suitable unicellular model for the last flagellate common ancestor of the streptophytes. Mesostigma shares more genes with the embryophytes than with the chlorophyte Chlamydomonas reinhardtii, although both organisms are flagellate unicells. Thus, it seems likely that several major physiological changes (e.g. in the regulation of photosynthesis

Marine snow microbial communities: scaling of abundances with aggregate size

DEFF Research Database (Denmark)

Kiørboe, Thomas

2003-01-01

Marine aggregates are inhabited by diverse microbial communities, and the concentration of attached microbes typically exceeds concentrations in the ambient water by orders of magnitude. An extension of the classical Lotka-Volterra model, which includes 3 trophic levels (bacteria, flagellates...... are controlled by flagellate grazing, while flagellate and ciliate populations are governed by colonization and detachment. The model also suggests that microbial populations are turned over rapidly (1 to 20 times d-1) due to continued colonization and detachment. The model overpredicts somewhat the scaling...... of microbial abundances with aggregate size observed in field-collected aggregates. This may be because it disregards the aggregation/disaggregation dynamics of aggregates, as well as interspecific interactions between bacteria....

Formation of large colonies: a defense mechanism of Microcystis aeruginosa under continuous grazing pressure by flagellate Ochromonas sp.

Directory of Open Access Journals (Sweden)

Fanxiang Kong

2012-01-01

Full Text Available Induced colony formation under grazing pressure has been reported in our previous results. However, the colonies induced in these studies comprised only tens of cells which are far smaller than the naturally occurring colonies. In this work, unicellular Microcystis aeruginosa Kützing were co-cultivated with flagellate Ochromonas sp. for 50 d to investigate colony formation in M. aeruginosa under continuous grazing pressure. Results revealed that colonial M. aeruginosa formed on the 10th d under the grazing pressure of flagellate. These algal colonies resulted from the daughter cells of freshly dividing cells that failed to separate during the reproductive process. The diameters and cell numbers of the colonies increased slowly with time. Under continuous grazing pressure by Ochromonas sp. for 50 d, the diameter of some colonies reached over 180 μm. Analysis showed that the extracellular polysaccharide (EPS content and relative gas vesicle (RGV of each cell increased significantly after colony formation. However, there was no significant difference on the monosaccharide composition between unicellular and colonial M. aeruginosa. The loose aggregation of cells in the floating colonies suggests that a correlation probably exists between cell compactness and colony buoyancy.

Accumulation of Dissolved DMSP by Marine Bacteria and its Degradation Via Bacterivory

Science.gov (United States)

Wolfe, Gordon V.

1996-01-01

Several bacterial isolates enriched from seawater using complex media were able to accumulate dimethylsulfoniopropionate (DMSP) from media into cells over several hours without degrading it. Uptake only occurred in metabolically active cells, and was repressed in some strains by the presence of additional carbon sources. Accumulation was also more rapid in osmotically-stressed cells, suggesting DMSP is used as an osmotic solute. Uptake could be blocked by inhibitors of active transport systems (2,4-dinitrophenol, azide, arsenate) and of protein synthesis (chloramphenicol). Some structural analogs such as glycine betaine and S-methyl methionine also blocked DMSP uptake, suggesting that the availability of alternate organic osmolytes may influence DMSP uptake. Stresses such as freezing, heating, or osmotic down shock resulted in partial release of DMSP back to the medium. One strain which contained a DMSP-lyase was also able to accumulate DMSP, and DMS was only produced in the absence of alternate carbon sources. Bacteria containing DMSP were prepared as prey for bacterivorous ciliates and flagellates, to examine the fate of the DMSP during grazing. In all cases, predators metabolized the DMSP in bacteria. In some cases, DMS was produced, but it is not clear if this was due to the predators or to associated bacteria in the non-axenic grazer cultures. Bacterivores may influence DMSP cycling by either modulating populations of DMSP-metabolizing bacteria, or by metabolizing DMSP accumulated by bacterial prey.

Food web in biological wastewater treatment processes. Who eats whom?; La cadena trofica en los sistemas de depuracion biologicos Quien se come a quien?

Energy Technology Data Exchange (ETDEWEB)

Mas Aceves, M.

2007-07-01

The organic matter coming to the biological system is assimilated by bacteria and protozoa (flagellated and gymnamoebae mainly). The majority of ciliates, flagellates or gymnamoebae protozoa are bacteria predators (whether disperse, floc-forming or filamentous bacteria) and some of those protozoa are able to feed on other protozoa. Therefore, and due to the great variability of food target in protozoa communities, a wide variety of food strategies can be described. so, gain knowledge on protozoa feeding strategies allows a better understanding of food transference efficiency from one trophic stage to another, and therefore, increasing the knowledge of biological wastewater treatment systems. (Author) 32 refs.

Description of Pyramimonas diskoicola sp. nov. and the importance of the flagellate Pyramimonas (Prasinophyceae) in Greenland sea ice during the winter–spring transition

DEFF Research Database (Denmark)

Harðardóttir, Sara; Lundholm, Nina; Moestrup, Øjvind

2014-01-01

Pyramimonas Schmarda is a genus of unicellular green flagellates, recorded in marine water and sea ice samples. Pyramimonas is within the prey size range of the most important protozoan grazers in Disko Bay, West Greenland, where this study took place. Despite the potential ecological importance...

Are grazer-induced adaptations of bacterial abundance and morphology timedependent?

Directory of Open Access Journals (Sweden)

Gianluca CORNO

2006-02-01

Full Text Available Predation by protists is a well known force that shapes bacterial communities and can lead to filamentous forms and aggregations of large cell clusters. These classic resistance strategies were observed as a direct consequence of predation by heteroand mixotrophic flagellates (the main group of bacteria predators in water on natural assemblages of bacteria and on single plastic strains. Recently it was shown that a long time exposure (about 30 days of a bacterial strain, characterized by high degree of phenotypic plasticity, to flagellates, without direct predation, enhanced the formation of resistant forms (filaments in a continuous culture system. Target prey populations and predators were separated by a dialysis membrane. Moreover, the positive impact on bacterial growth, due to the chemical excretes released by flagellates was demonstrated for exudates of photosynthetic activity. The same positive impact may also be seen in response to exudates related to grazing. In this study, two short-term experiments (<100 hours were conducted to test for modifications in the morphology and productivity of three different bacterial strains that were induced by the presence of active predators, but without direct predation. The growth and morphological distribution of each of the selected strains was tested separately using batch cultures. Cultures were either enriched with carbon in the presence or absence of flagellate predators, or included pre-filtered exudates from flagellate activity. In a second experiment, bottles were provided with a central dialysis bag that contained active flagellates, and were inoculated with the selected bacterial strains. In this way, bacteria were exposed to the presence of predators without direct predation. The bacterial strains used in this experience were characterised by a high degree of phenotypic plasticity and exhibited different successful strategies of resistance against grazing. The flagellates selected as

Development and application of a most probable number-PCR assay to quantify flagellate populations in soil samples

DEFF Research Database (Denmark)

Fredslund, Line; Ekelund, Flemming; Jacobsen, Carsten Suhr

2001-01-01

This paper reports on the first successful molecular detection and quantification of soil protozoa. Quantification of heterotrophic flagellates and naked amoebae in soil has traditionally relied on dilution culturing techniques, followed by most-probable-number (MPN) calculations. Such methods...... are biased by differences in the culturability of soil protozoa and are unable to quantify specific taxonomic groups, and the results are highly dependent on the choice of media and the skills of the microscopists. Successful detection of protozoa in soil by DNA techniques requires (i) the development...

[Mutants of bacterium Azospirillum brasilense Sp245 with Omegon insertion in mmsB or fabG genes of lipid metabolism are defective in motility and flagellation].

Science.gov (United States)

Kovtunov, E A; Shelud'ko, A V; Chernyshova, M P; Petrova, L P; Katsy, E I

2013-11-01

Bacteria Azospirillum brasilense have mixed flagellation: in addition to the polar flagellum, numerous lateral flagella are formed in their cells on medium with increased density. Flagella determine the active swimming and swarming capacities of azospirilla. Using A. brasilense Sp245 as an example, we showed that the Omegon-Km artificial transposon insertion into the chromosomal gene for 3-hydroxyisobutyrate dehydrogenase (mmsB) was concurrent with the appearance of significant defects in the formation of polar flagella and with the paralysis of lateral flagella. The Sp245 mutant with the Omegon insertion into the plasmid AZOBR_p1-borne gene for 3-oxoacyl-[acyl-carrier protein]-reductase (fabG) showed the complete loss of flagella and the swarming capacity, as well as significant defects in polar flagellar assembly (though some cells are still motile in liquid medium). The viability of the A. brasilense Sp245 mutants with the Omegon insertion into the mmsB or fabG gene was not reduced. No considerable differences in the fatty acid composition of whole cell lipid extracts were found for the A. brasilense Sp245 strain and its mmsB and fabG mutants.

Clinical and pathological observations on natural infections of cryptosporidiosis and flagellate protozoa in leopard geckos (Eublepharis macularius).

Science.gov (United States)

Taylor, M A; Geach, M R; Cooley, W A

1999-12-11

A group of adult leopard geckos (Eublepharis macularius) which had been losing weight for several months were found to be infected with Cryptosporidium species. Histological and electron microscopical investigations on the intestines of five of the lizards revealed the presence of large numbers of the developmental stages of Cryptosporidium species attached to the mucosal surface of the lower intestine, and large numbers of flagellate protozoa, suspected to be predominantly Trichomonas species, in the gut lumen. The clinical signs were attributed to the presence of one or both types of parasites.

Killing the killer: predation between protists and predatory bacteria.

Science.gov (United States)

Johnke, Julia; Boenigk, Jens; Harms, Hauke; Chatzinotas, Antonis

2017-05-01

Predation by microbes is one of the main drivers of bacterial mortality in the environment. In most ecosystems multiple micropredators compete at least partially for the same bacterial resource. Predatory interactions between these micropredators might lead to shifts within microbial communities. Integrating these interactions is therefore crucial for the understanding of ecosystem functioning. In this study, we investigated the predation between two groups of micropredators, i.e. phagotrophic protists and Bdellovibrio and like organisms (BALOs). BALOs are obligate predators of Gram-negative bacteria. We hypothesised that protists can prey upon BALOs despite the small size and high swimming speed of the latter, which makes them potentially hard to capture. Predation experiments including three protists, i.e. one filter feeder and two interception feeder, showed that BALOs are a relevant prey for these protists. The growth rate on BALOs differed for the respective protists. The filter feeding ciliate was growing equally well on the BALOs and on Escherichia coli, whereas the two flagellate species grew less well on the BALOs compared to E. coli. However, BALOs might not be a favourable food source in resource-rich environments as they are not enabling all protists to grow as much as on bacteria of bigger volume. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

A simple and low-toxic method of preparing small specimens of bacteria, flagellates and their likes for Scanning Electron Microscopy

DEFF Research Database (Denmark)

Møller, O. S.; Buchman, K.; Dalsgaard, Inger

2013-01-01

The preparation of samples of bacteria and other very small organisms (Electron Microscopy is often complex and intricate, which typically involve the use of specialized filter systems, complex handling and toxic chemicals. Based on the methods described in the literature...

Enrichment of omnivorous cercozoan nanoflagellates from coastal Baltic Sea waters.

Directory of Open Access Journals (Sweden)

Kasia Piwosz

Full Text Available Free-living nano-sized flagellates are important bacterivores in aquatic habitats. However, some slightly larger forms can also be omnivorous, i.e., forage upon both bacterial and eukaryotic resources. This hitherto largely ignored feeding mode may have pronounced implications for the interpretation of experiments about protistan bacterivory. We followed the response of an uncultured group of omnivorous cercozoan nanoflagellates from the Novel Clade 2 (Cerc_BAL02 to experimental food web manipulation in samples from the Gulf of Gdańsk (Southern Baltic Sea. Seawater was either prefiltered through 5 µm filters to exclude larger predators of nanoflagellates (F-treatment, or prefiltered and subsequently 1∶10 diluted with sterile seawater (F+D-treatment to stimulate the growth of both, flagellates and bacteria. Initially, Cerc_BAL02 were rapidly enriched under both conditions. They foraged on both, eukaryotic prey and bacteria, and were highly competitive at low concentrations of food. However, these omnivores were later only successful in the F+D treatment, where they eventually represented almost one fifth of all aplastidic nanoflagellates. By contrast, their numbers stagnated in the F-treatment, possibly due to top-down control by a concomitant bloom of other, unidentified flagellates. In analogy with observations about the enrichment of opportunistically growing bacteria in comparable experimental setups we suggest that the low numbers of omnivorous Cerc_Bal02 flagellates in waters of the Gulf of Gdańsk might also be related to their vulnerability to grazing pressure.

Live-cell super-resolution imaging of intrinsically fast moving flagellates

International Nuclear Information System (INIS)

Glogger, M; Subota, I; Spindler, M-C; Engstler, M; Fenz, S F; Stichler, S; Bertlein, S; Teßmar, J; Groll, J

2017-01-01

Recent developments in super-resolution microscopy make it possible to resolve structures in biological cells at a spatial resolution of a few nm and observe dynamical processes with a temporal resolution of ms to μ s. However, the optimal structural resolution requires repeated illumination cycles and is thus limited to chemically fixed cells. For live cell applications substantial improvement over classical Abbe-limited imaging can already be obtained in adherent or slow moving cells. Nonetheless, a large group of cells are fast moving and thus could not yet be addressed with live cell super-resolution microscopy. These include flagellate pathogens like African trypanosomes, the causative agents of sleeping sickness in humans and nagana in livestock. Here, we present an embedding method based on a in situ forming cytocompatible UV-crosslinked hydrogel. The fast cross-linking hydrogel immobilizes trypanosomes efficiently to allow microscopy on the nanoscale. We characterized both the trypanosomes and the hydrogel with respect to their autofluorescence properties and found them suitable for single-molecule fluorescence microscopy (SMFM). As a proof of principle, SMFM was applied to super-resolve a structure inside the living trypanosome. We present an image of a flagellar axoneme component recorded by using the intrinsic blinking behavior of eYFP. (paper)

Exploring Anopheles gut bacteria for Plasmodium blocking activity

Science.gov (United States)

Bahia, Ana C; Dong, Yuemei; Blumberg, Benjamin J; Mlambo, Godfree; Tripathi, Abhai; BenMarzouk-Hidalgo, Omar J; Chandra, Ramesh; Dimopoulos, George

2014-01-01

SUMMARY Malaria parasite transmission requires the successful development of Plasmodium gametocytes into flagellated microgametes upon mosquito blood ingestion, and the subsequent fertilization of microgametes and macrogametes for the development of motile zygotes, called ookinetes, which invade and transverse the Anopheles vector mosquito midgut at around 18-36 h after blood ingestion. Within the mosquito midgut, the malaria parasite has to withstand the mosquito's innate immune response and the detrimental effect of its commensal bacterial flora. We have assessed the midgut colonization capacity of 5 gut bacterial isolates from field-derived, and 2 from laboratory colony, mosquitoes and their effect on Plasmodium development in vivo and in vitro, along with their impact on mosquito survival. Some bacterial isolates activated the mosquito's immune system, affected the mosquito's life span, and were capable of blocking Plasmodium development. We have also shown that the ability of these bacteria to inhibit the parasites is likely to involve different mechanisms and factors. A Serratia marcescens isolate was particularly efficient in colonizing the mosquitoes’ gut, compromising mosquito survival, and inhibiting both sexual- and asexual-stage Plasmodium through secreted factors, thereby rendering it a potential candidate for the development of a malaria transmission intervention strategy. PMID:24428613

Carbon partitioning in the food web of a high mountain lake: from bacteria to zooplankton

Directory of Open Access Journals (Sweden)

Alessandra PUGNETTI

1999-08-01

Full Text Available The organisms of the microbial loop in Lake Paione Superiore (LPS, a high mountain lake in the Italian Alpine region, were studied together with phytoplankton and zooplankton for three successive years. The biomass of bacteria, HNF (heterotrophic nanoflagellates, ciliates and phytoplankton, as mean carbon concentration in the three years, was 30 and 37 μg C l-1 near the surface (SUR and the bottom (BOT respectively. Under the ice-cover the mean biomass carbon decreased especially at the BOT, whereas at SUR the decrease was less evident due to the maintenance of higher phytoplankton biomass (mixotrophic flagellates. In LPS ~50% of the carbon was confined in bacteria, 20% in protozoa and 30% in phytoplankton. The ratio Autotrophs/Heterotrophs was lower than 1 (mean: 0,97 at SUR and 0,58 at BOT thus indicating a system with a predominance of the heterotrophs. This might be the result of light inhibition of algal growth coupled to a production of dissolved carbon, utilized by bacteria. During late summer the peak of Daphnia longispina, the main component of the zooplankton of LPS, increased the carbon content in the lake to a total of 158 and 300 μg C l-1 in 1997 and 1998 respectively. At the late summer peaks, zooplankton represented from 78 to 89% of the total carbon of the pelagic communities. Furthermore, the presence of Daphnia could be responsible for a decrease in the biomass carbon of a variety of organisms (algae, protozoa and bacteria. It may be possible that this is an instance of zooplankton grazing on algae, protozoa and also bacteria, as Daphnia has very broad niches and may eat pico-, nanoplankton and small ciliates. In the oligotrophic LPS, a diet which also includes protozoa could give Daphnia a further chance of survival, as ciliates are an important source of fatty acids and sterols.

Seasonal variability in irradiance affects herbicide toxicity to the marine flagellate Dunaliella tertiolecta

Directory of Open Access Journals (Sweden)

Sascha eSjollema

2014-06-01

Full Text Available Photosynthetically Active Radiation (PAR and Ultraviolet Radiation (UVR of the solar spectrum affect microalgae directly and modify the toxicity of phytotoxic compounds present in water. As a consequence seasonal variable PAR and UVR levels are likely to modulate the toxic pressure of contaminants in the field. Therefore the present study aimed to determine the toxicity of two model contaminants, the herbicides diuron and Irgarol®1051, under simulated irradiance conditions mimicking different seasons. Irradiance conditions of spring and autumn were simulated with a set of Light Emitting Diodes (LEDs. Toxicity of both herbicides was measured individually and in a mixture by determining the inhibition of photosystem II efficiency (ΦPSII of the marine flagellate Dunaliella teriolecta using Pulse Amplitude Modulation (PAM fluorometry. Toxicity of the single herbicides was higher under simulated spring irradiance than under autumn irradiance and this effect was also observed for mixtures of the herbicides. This irradiance dependent toxicity indicates that herbicide toxicity in the field is seasonally variable. Consequently toxicity tests under standard light conditions may overestimate or underestimate the toxic effect of phytotoxic compounds.

Dynamic states of swimming bacteria in a nematic liquid crystal cell with homeotropic alignment

International Nuclear Information System (INIS)

Zhou, Shuang; Harvard University, Cambridge, MA; Tovkach, Oleh; University of Massachusetts, Amherst, MA; Golovaty, Dmitry

2017-01-01

Flagellated bacteria such as Escherichia coli and Bacillus subtilis exhibit effective mechanisms for swimming in fluids and exploring the surrounding environment. In isotropic fluids such as water, the bacteria change swimming direction through the run-and-tumble process. Lyotropic chromonic liquid crystals (LCLCs) have been introduced recently as an anisotropic environment in which the direction of preferred orientation, the director, guides the bacterial trajectories. In this work, we describe the behavior of bacteria B. subtilis in a homeotropic LCLC geometry, in which the director is perpendicular to the bounding plates of a shallow cell. We demonstrate that the bacteria are capable of overcoming the stabilizing elastic forces of the LCLC and swim perpendicularly to the imposed director (and parallel to the bounding plates). The effect is explained by a finite surface anchoring of the director at the bacterial body; the role of surface anchoring is analyzed by numerical simulations of a rod realigning in an otherwise uniform director field. Shear flows produced by a swimming bacterium cause director distortions around its body, as evidenced both by experiments and numerical simulations. These distortions contribute to a repulsive force that keeps the swimming bacterium at a distance of a few micrometers away from the bounding plates. The homeotropic alignment of the director imposes two different scenarios of bacterial tumbling: one with an 180° reversal of the horizontal velocity and the other with the realignment of the bacterium by two consecutive 90° turns. Finally, in the second case, the angle between the bacterial body and the imposed director changes from 90° to 0° and then back to 90°; the new direction of swimming does not correlate with the previous swimming direction.

Propulsion of liposomes using bacterial motors

International Nuclear Information System (INIS)

Zhang Zhenhai; Li Kejie; Li Zhifei; Yu Wei; Xie Zhihong; Shi Zhiguo

2013-01-01

Here we describe the utilization of flagellated bacteria as actuators to propel spherical liposomes by attaching bacteria to the liposome surface. Bacteria were stably attached to liposomes using a cross-linking antibody. The effect of the number of attached bacteria on propulsion speed was experimentally determined. The effects of bacterial propulsion on the bacteria–antibody–liposome complex were stochastic. We demonstrated that liposomal mobility increased when bacteria were attached, and the propulsion speed correlated with the number of bacteria. (paper)

Live-cell super-resolution imaging of intrinsically fast moving flagellates

Science.gov (United States)

Glogger, M.; Stichler, S.; Subota, I.; Bertlein, S.; Spindler, M.-C.; Teßmar, J.; Groll, J.; Engstler, M.; Fenz, S. F.

2017-02-01

Recent developments in super-resolution microscopy make it possible to resolve structures in biological cells at a spatial resolution of a few nm and observe dynamical processes with a temporal resolution of ms to μs. However, the optimal structural resolution requires repeated illumination cycles and is thus limited to chemically fixed cells. For live cell applications substantial improvement over classical Abbe-limited imaging can already be obtained in adherent or slow moving cells. Nonetheless, a large group of cells are fast moving and thus could not yet be addressed with live cell super-resolution microscopy. These include flagellate pathogens like African trypanosomes, the causative agents of sleeping sickness in humans and nagana in livestock. Here, we present an embedding method based on a in situ forming cytocompatible UV-crosslinked hydrogel. The fast cross-linking hydrogel immobilizes trypanosomes efficiently to allow microscopy on the nanoscale. We characterized both the trypanosomes and the hydrogel with respect to their autofluorescence properties and found them suitable for single-molecule fluorescence microscopy (SMFM). As a proof of principle, SMFM was applied to super-resolve a structure inside the living trypanosome. We present an image of a flagellar axoneme component recorded by using the intrinsic blinking behavior of eYFP. , which features invited work from the best early-career researchers working within the scope of J Phys D. This project is part of the Journal of Physics series’ 50th anniversary celebrations in 2017. Susanne Fenz was selected by the Editorial Board of J Phys D as an Emerging Talent/Leader.

Trophic level stability-inducing effects of predaceous early juvenile fish in an estuarine mesocosm study.

Directory of Open Access Journals (Sweden)

Ryan J Wasserman

Full Text Available Classically, estuarine planktonic research has focussed largely on the physico-chemical drivers of community assemblages leaving a paucity of information on important biological interactions.Within the context of trophic cascades, various treatments using in situ mesocosms were established in a closed estuary to highlight the importance of predation in stabilizing estuarine plankton abundances. Through either the removal (filtration or addition of certain planktonic groups, five different trophic systems were established. These treatments contained varied numbers of trophic levels and thus different "predators" at the top of the food chain. The abundances of zooplankton (copepod and polychaete, ciliate, micro-flagellate, nano-flagellate and bacteria were investigated in each treatment, over time. The reference treatment containing apex zooplanktivores (early juvenile mullet and plankton at natural densities mimicked a natural, stable state of an estuary. Proportional variability (PV and coefficient of variation (CV of temporal abundances were calculated for each taxon and showed that apex predators in this experimental ecosystem, when compared to the other systems, induced stability. The presence of these predators therefore had consequences for multiple trophic levels, consistent with trophic cascade theory.PV and CV proved useful indices for comparing stability. Apex predators exerted a stabilizing pressure through feeding on copepods and polychaetes which cascaded through the ciliates, micro-flagellates, nano-flagellates and bacteria. When compared with treatments without apex predators, the role of predation in structuring planktonic communities in closed estuaries was highlighted.

pH-Taxis of Biohybrid Microsystems

Science.gov (United States)

Zhuang, Jiang; Wright Carlsen, Rika; Sitti, Metin

2015-06-01

The last decade has seen an increasing number of studies developing bacteria and other cell-integrated biohybrid microsystems. However, the highly stochastic motion of these microsystems severely limits their potential use. Here, we present a method that exploits the pH sensing of flagellated bacteria to realize robust drift control of multi-bacteria propelled microrobots. Under three specifically configured pH gradients, we demonstrate that the microrobots exhibit both unidirectional and bidirectional pH-tactic behaviors, which are also observed in free-swimming bacteria. From trajectory analysis, we find that the swimming direction and speed biases are two major factors that contribute to their tactic drift motion. The motion analysis of microrobots also sheds light on the propulsion dynamics of the flagellated bacteria as bioactuators. It is expected that similar driving mechanisms are shared among pH-taxis, chemotaxis, and thermotaxis. By identifying the mechanism that drives the tactic behavior of bacteria-propelled microsystems, this study opens up an avenue towards improving the control of biohybrid microsystems. Furthermore, assuming that it is possible to tune the preferred pH of bioactuators by genetic engineering, these biohybrid microsystems could potentially be applied to sense the pH gradient induced by cancerous cells in stagnant fluids inside human body and realize targeted drug delivery.

Modulation of pathogen-induced CCL20 secretion from HT-29 human intestinal epithelial cells by commensal bacteria.

LENUS (Irish Health Repository)

Sibartie, Shomik

2009-01-01

BACKGROUND: Human intestinal epithelial cells (IECs) secrete the chemokine CCL20 in response to infection by various enteropathogenic bacteria or exposure to bacterial flagellin. CCL20 recruits immature dendritic cells and lymphocytes to target sites. Here we investigated IEC responses to various pathogenic and commensal bacteria as well as the modulatory effects of commensal bacteria on pathogen-induced CCL20 secretion. HT-29 human IECs were incubated with commensal bacteria (Bifidobacterium infantis or Lactobacillus salivarius), or with Salmonella typhimurium, its flagellin, Clostridium difficile, Mycobacterium paratuberculosis, or Mycobacterium smegmatis for varying times. In some studies, HT-29 cells were pre-treated with a commensal strain for 2 hr prior to infection or flagellin stimulation. CCL20 and interleukin (IL)-8 secretion and nuclear factor (NF)-kappaB activation were measured using enzyme-linked immunosorbent assays. RESULTS: Compared to untreated cells, S. typhimurium, C. difficile, M. paratuberculosis, and flagellin activated NF-kappaB and stimulated significant secretion of CCL20 and IL-8 by HT-29 cells. Conversely, B. infantis, L. salivarius or M. smegmatis did not activate NF-kappaB or augment CCL20 or IL-8 production. Treatment with B. infantis, but not L. salivarius, dose-dependently inhibited the baseline secretion of CCL20. In cells pre-treated with B. infantis, C. difficile-, S. typhimurium-, and flagellin-induced CCL20 were significantly attenuated. B. infantis did not limit M. Paratuberculosis-induced CCL20 secretion. CONCLUSION: This study is the first to demonstrate that a commensal strain can attenuate CCL20 secretion in HT-29 IECs. Collectively, the data indicate that M. paratuberculosis may mediate mucosal damage and that B. infantis can exert immunomodulatory effects on IECs that mediate host responses to flagellin and flagellated enteric pathogens.

Effects of solar and artificial UV irradiation on motility and phototaxis in the flagellate, Euglena gracilis

International Nuclear Information System (INIS)

Haeder, D.-P.

1986-01-01

The effect of solar irradiation on the percentage of motile cells, their average speed and their phototactic orientation to white actinic light was studied in the flagellate, Euglena gracilis. Unfiltered solar radiation in midsummer during mid-day at a location near Lisboa, Portugal, was found to impair motility within 2 h. This effect is exclusively due to the UV-B component of the radiation and not due to UV-A, visible light or a temperature increase. Likewise, phototactic orientation was drastically impaired. Reduction of the solar UV-B irradiation by insertion of an ozone-flooded plexiglass cuvette partially reduced the inhibition and covering the cuvettes with glass prevented any decrease in motility and photoorientation. Similar results were found with artificial irradiation (Xe lamps). After inoculation, the motility of the population follows an optimum curve (optimum at 8 days). Also, the UV-B effect on motility was smallest after about one week and increased for younger and older cultures. (author)

The microbial community of Ophrydium versatile colonies: endosymbionts, residents, and tenants

Science.gov (United States)

Duval, B.; Margulis, L.

1995-01-01

Ophrydium versatile is a sessile peritrichous ciliate (Kingdom Protoctista, class Oligohymenophora, order Peritrichida, suborder Sessilina) that forms green, gelatinous colonies. Chlorophyll a and b impart a green color to Ophrydium masses due to 400-500 Chlorella-like endosymbionts in each peritrich. Ophrydium colonies, collected from two bog wetlands (Hawley and Leverett, Massachusetts) were analyzed for their gel inhabitants. Other protists include ciliates, mastigotes, euglenids, chlorophytes, and heliozoa. Routine constituents include from 50-100,000 Nitzschia per ml of gel and at least four other diatom genera (Navicula, Pinnularia, Gyrosigma, Cymbella) that may participate in synthesis of the gel matrix. Among the prokaryotes are filamentous and coccoid cyanobacteria, large rod-shaped bacteria, at least three types of spirochetes and one unidentified Saprospira-like organism. Endosymbiotic methanogenic bacteria, observed using fluorescence microscopy, were present in unidentified hypotrichous ciliates. Animals found inside the gel include rotifers, nematodes, and occasional copepods. The latter were observed in the water reservoir of larger Ophrydium masses. From 30-46% of incident visible radiation could be attenuated by Ophrydium green jelly masses in laboratory observations. Protargol staining was used to visualize the elongate macronuclei and small micronucleus of O. versatile zooids and symbiotic algal nuclei. Electron microscopic analysis of the wall of the Chlorella-like symbiont suggests that although the Ophrydium zooids from British Columbia harbor Chlorella vulgaris, those from Hawley Bog contain Graesiella sp. The growth habit in the photic zone and loose level of individuation of macroscopic Ophrydium masses are interpretable as extant analogs of certain Ediacaran biota: colonial protists in the Vendian fossil record.

Changes in the flagellar bundling time account for variations in swimming behavior of flagellated bacteria in viscous media

Science.gov (United States)

Qu, Zijie; Temel, Fatma; Henderikx, Rene; Breuer, Kenneth

2017-11-01

The motility of bacteria E.coli in viscous fluids has been widely studied, although conflicting results on the effect of viscosity on swimming speed abound. The swimming mode of wild-type E.coli is idealized as a run-and-tumble sequence in which periods of straight swimming at a constant speed are randomly interrupted by a tumble, defined as a sudden change of direction with a very low speed. Using a tracking microscope, we follow cells for extended time and find that the swimming behavior of a single cell can exhibit a variety of behaviors including run-and-tumble and ``slow-random-walk'' in which the cells move at relatively low speed without the characteristic run. Although the characteristic swimming speed varies between individuals and in different polymer solutions, we find that the skewness of the speed distribution is solely a function of viscosity, and uniquely determines the ratio of the average speed to the characteristic run speed. Using Resistive Force Theory and the cell-specific measured characteristic run speed, we show that differences in the swimming behavior observed in solutions of different viscosity are due to changes in the flagellar bundling time, which increases as the viscosity rises, due to lower rotation rate of the flagellar motor. National Science Foundation.

Complex coevolutionary history of symbiotic Bacteroidales bacteria of various protists in the gut of termites

Science.gov (United States)

Noda, Satoko; Hongoh, Yuichi; Sato, Tomoyuki; Ohkuma, Moriya

2009-01-01

Background The microbial community in the gut of termites is responsible for the efficient decomposition of recalcitrant lignocellulose. Prominent features of this community are its complexity and the associations of prokaryotes with the cells of cellulolytic flagellated protists. Bacteria in the order Bacteroidales are involved in associations with a wide variety of gut protist species as either intracellular endosymbionts or surface-attached ectosymbionts. In particular, ectosymbionts exhibit distinct morphological patterns of the associations. Therefore, these Bacteroidales symbionts provide an opportunity to investigate not only the coevolutionary relationships with the host protists and their morphological evolution but also how symbiotic associations between prokaryotes and eukaryotes occur and evolve within a complex symbiotic community. Results Molecular phylogeny of 31 taxa of Bacteroidales symbionts from 17 protist genera in 10 families was examined based on 16S rRNA gene sequences. Their localization, morphology, and specificity were also examined by fluorescent in situ hybridizations. Although a monophyletic grouping of the ectosymbionts occurred in three related protist families, the symbionts of different protist genera were usually dispersed among several phylogenetic clusters unique to termite-gut bacteria. Similar morphologies of the associations occurred in multiple lineages of the symbionts. Nevertheless, the symbionts of congeneric protist species were closely related to one another, and in most cases, each host species harbored a unique Bacteroidales species. The endosymbionts were distantly related to the ectosymbionts examined so far. Conclusion The coevolutionary history of gut protists and their associated Bacteroidales symbionts is complex. We suggest multiple independent acquisitions of the Bacteroidales symbionts by different protist genera from a pool of diverse bacteria in the gut community. In this sense, the gut could serve as a

Extra-chromosomal DNA maintenance in Bacillus subtilis, dependence on flagellation factor FliF and moonlighting mediator EdmS.

Science.gov (United States)

Hakumai, Yuichi; Shimomoto, Kouko; Ashiuchi, Makoto

2015-05-15

Extra-chromosomal DNA maintenance (EDM) as an important process in the propagation and genetic engineering of microbes. Bacillus subtilis EdmS (formerly PgsE), a protein comprising 55 amino acids, is a mediator of the EDM process. In this study, the effect of mutation of global regulators on B. subtilis EDM was examined. Mutation of the swrA gene abolished EdmS-mediated EDM. It is known that swrA predominantly regulates expression of the fla/che operon in B. subtilis. We therefore performed EDM analysis using fla/che-deletion mutants and identified an EDM-mediated EDM cooperator in the flgB-fliL region. Further genetic investigation identified the flagellation factor FliF is a crucial EDM cooperator. To our knowledge, this is the first observation of the moonlighting function of FliF in DNA maintenance. Copyright © 2015 Elsevier Inc. All rights reserved.

Upper Arctic Ocean water masses harbor distinct communities of heterotrophic flagellates

Directory of Open Access Journals (Sweden)

A. Monier

2013-06-01

Full Text Available The ubiquity of heterotrophic flagellates (HFL in marine waters has been recognized for several decades, but the phylogenetic diversity of these small (ca. 0.8–20 μm cell diameter, mostly phagotrophic protists in the upper pelagic zone of the ocean is underappreciated. Community composition of microbes, including HFL, is the result of past and current environmental selection, and different taxa may be indicative of food webs that cycle carbon and energy very differently. While all oceanic water columns can be density stratified due to the temperature and salinity characteristics of different water masses, the Arctic Ocean is particularly well stratified, with nutrients often limiting in surface waters and most photosynthetic biomass confined to a subsurface chlorophyll maximum layer, where light and nutrients are both available. This physically well-characterized system provided an opportunity to explore the community diversity of HFL from different water masses within the water column. We used high-throughput DNA sequencing techniques as a rapid means of surveying the diversity of HFL communities in the southern Beaufort Sea (Canada, targeting the surface, the subsurface chlorophyll maximum layer (SCM and just below the SCM. In addition to identifying major clades and their distribution, we explored the micro-diversity within the globally significant but uncultivated clade of marine stramenopiles (MAST-1 to examine the possibility of niche differentiation within the stratified water column. Our results strongly suggested that HFL community composition was determined by water mass rather than geographical location across the Beaufort Sea. Future work should focus on the biogeochemical and ecological repercussions of different HFL communities in the face of climate-driven changes to the physical structure of the Arctic Ocean.

Longitudinal variation of attributes from flagellate protozoan community in tropical streams = Variação longitudinal dos atributos da comunidade de protozoários flagelados de riachos tropicais

Directory of Open Access Journals (Sweden)

Janielly Carvalho Camargo

2011-04-01

Full Text Available This study verified the existence of longitudinal patterns in speciescomposition, richness, density and biomass of flagellate protozoan in tropical streams and investigated whether the possible zonation patterns are different between two periods of the year. For this, samplings were carried out in three regions from 10 streams, during the summer and winter. The flagellate community may be considered species-rich, because it was represented by 106 taxa, belonging to 8 orders and 1 residual group. The values of density and biomass are greater than those commonly found in other lotic environments, with mean values close to 2.3x104 cels. mL-1 and 150.8 ƒÊgC L-1. We did not observe any conspicuous and significant longitudinal pattern of the attributes from flagellates community. Only temporal variations of these attributes were verified. The Pearson Correlation evidenced that this temporal patterns was mainly driven by the nutrients availability, temperature and dissolved oxygen, since, the higher values of species richness, density and biomass were recorded during the winter, when the higher concentrations of nutrients and dissolved oxygen and lower temperatures were registered. In summary, the absence of patterns may be ascribed to the unidirectional and continuous flow from lotic environments.O presente estudo objetivou verificar a existencia de padroes longitudinais de composicao, riqueza de especies, densidade e biomassa da comunidade de protozoarios flagelados de riachos tropicais e, ainda, investigar se os possiveis padroes de zonacao sao diferentes entre dois periodos do ano. Foram realizadas coletas em tres regioes ao longo de dez riachos, durante os periodos de verao e inverno. A comunidade de protozoarios flagelados pode ser considerada bastante rica, sendo representada por 106 taxons pertencentes a oito ordens e um grupo residual. Os valores de densidade e biomassa registrados encontram-se acima dos valores comumente encontradosem

Abundance and size structure of planktonic protist communities in a Neotropical floodplain: effects of top-down and bottom-up controls

Directory of Open Access Journals (Sweden)

Bianca Ramos de Meira

2017-12-01

Full Text Available Abstract: Aim: We aimed to assess the influence of bottom-up and top-down control mechanisms on the abundance and size structure of protist communities (heterotrophic flagellates and ciliates. We formulated the following hypothesis: bottom-up control mechanisms, related to the availability of resources in the environment, are responsible for structuring the abundance of these communities, whereas top-down control mechanisms, related to predation effects, determine the size pattern of these organisms. Methods Samples for planktonic organisms were taken in 20 shallow lakes belonging to the upper Paraná River floodplain. We evaluated linear regression models to select the best model which predicts the patterns observed according to Akaike Information Criterion. Results The best models selected to explain the abundance of heterotrophic flagellates included negative relations with picophytoplankton abundance and positive with rotifers abundance, while for their size structure, negative relationships were found with heterotrophic bacteria, ciliates and rotifers biovolumes. In relation to the ciliates, their abundances were positively related to the rotifers and picophytoplankton abundances and negatively with the heterotrophic bacteria abundance. On the other hand, for the size structure, the best models selected strong negative relations with the microcrustaceans biovolumes, in addition to relations with the different fractions of the phytoplankton. Conclusion For both flagellates and ciliates, their abundance is being mainly regulated by a bottom up control mechanism, whereas for the size structure the results showed that both food resources and predators were important, indicating that bottom-up and top-down mechanisms act simultaneously in determining the size of these microorganisms.

Biomass reallocation within freshwater bacterioplankton induced by manipulating phosphorus availability and grazing

Czech Academy of Sciences Publication Activity Database

Posch, T.; Mindl, B.; Horňák, Karel; Jezbera, Jan; Salcher, M.M.; Sattler, B.; Sonntag, B.; Vrba, Jaroslav; Šimek, Karel

2007-01-01

Roč. 49, č. 3 (2007), s. 223-232 ISSN 0948-3055 R&D Projects: GA ČR(CZ) GA206/05/0007 Grant - others:ASF(AT) FWF P17554-B06 Institutional research plan: CEZ:AV0Z60170517 Keywords : bacterial biomass * bacteria-flagellate interactions * fluorescence in situ hybridization Subject RIV: EH - Ecology, Behaviour Impact factor: 2.385, year: 2007

Anaerobic bacteria

Science.gov (United States)

Anaerobic bacteria are bacteria that do not live or grow when oxygen is present. In humans, these bacteria ... Brook I. Diseases caused by non-spore-forming anaerobic bacteria. In: Goldman L, Schafer AI, eds. Goldman-Cecil ...

Bacterial growth on macrophyte leachate and fate of bacterial production

International Nuclear Information System (INIS)

Findlay, S.; Carlough, L.; Crocker, M.T.; Gill, H.K.; Meyer, J.L.; Smith, P.J.

1986-01-01

The role bacteria play in transferring organic carbon to other trophic levels in aquatic ecosystems depends on the efficiency with which they convert dissolved organic [ 14 C]-labelled carbon into bacterial biomass and on the ability of consumers to graze bacteria. The authors have measured the conversion efficiency for bacteria growing on macrophyte-derived dissolved organic carbon and estimated the amount of bacterial production removed by grazing. Bacteria converted this DOC into new tissue with an efficiency of 53%, substantially higher than the apparent conversion efficiency of macrophyte-derived particulate organic carbon or other types of DOC. Two estimates of grazing indicate that the decline in bacterial numbers after the bloom was probably due to grazing by flagellates. These results show the significance of the bacterial link between DOC and other trophic levels

Swarming and complex pattern formation in Paenibacillus vortex studied by imaging and tracking cells

Directory of Open Access Journals (Sweden)

Jacob Eshel

2008-02-01

Full Text Available Abstract Background Swarming motility allows microorganisms to move rapidly over surfaces. The Gram-positive bacterium Paenibacillus vortex exhibits advanced cooperative motility on agar plates resulting in intricate colonial patterns with geometries that are highly sensitive to the environment. The cellular mechanisms that underpin the complex multicellular organization of such a simple organism are not well understood. Results Swarming by P. vortex was studied by real-time light microscopy, by in situ scanning electron microscopy and by tracking the spread of antibiotic-resistant cells within antibiotic-sensitive colonies. When swarming, P. vortex was found to be peritrichously flagellated. Swarming by the curved cells of P. vortex occurred on an extremely wide range of media and agar concentrations (0.3 to 2.2% w/v. At high agar concentrations (> 1% w/v rotating colonies formed that could be detached from the main mass of cells by withdrawal of cells into the latter. On lower percentage agars, cells moved in an extended network composed of interconnected "snakes" with short-term collision avoidance and sensitivity to extracts from swarming cells. P. vortex formed single Petri dish-wide "supercolonies" with a colony-wide exchange of motile cells. Swarming cells were coupled by rapidly forming, reversible and non-rigid connections to form a loose raft, apparently connected via flagella. Inhibitors of swarming (p-Nitrophenylglycerol and Congo Red were identified. Mitomycin C was used to trigger filamentation without inhibiting growth or swarming; this facilitated dissection of the detail of swarming. Mitomycin C treatment resulted in malcoordinated swarming and abortive side branch formation and a strong tendency by a subpopulation of the cells to form minimal rotating aggregates of only a few cells. Conclusion P. vortex creates complex macroscopic colonies within which there is considerable reflux and movement and interaction of cells. Cell

The effect of toxic loads on effluent purification systems

Energy Technology Data Exchange (ETDEWEB)

Cillie, G.C.; Hart, O.O.; Davies, T.R.; Hassett, A.J.

1977-04-01

Deterioration of the performance of biological wastewater treatment plants at Daspoort Sewage Works, Pretoria, South Africa, during 1975 was attributed to toxic material in the sewage. Unusually high concentrations of mercury, phenol, chromium, and an organophosphorus compound were detected. These substances singly or in combination could have been responsible for the deterioration. Data from the biological plants and research units at Daspoort are collected and reviewed to evaluate the water quality effects of the period of low performance. Encystation by peritrichous ciliates caused high bacteria counts in biofilter effluents. Nitrification declined rapidly and recovery was delayed, while carbon oxidation was affected to a limited extent. The water product was of the same quality throughout, even when the influent was little better than settled sewage. (12 graphs, 4 references, 3 tables)

The structure of the mitotic spindle and nucleolus during mitosis in the amebo-flagellate Naegleria.

Science.gov (United States)

Walsh, Charles J

2012-01-01

Mitosis in the amebo-flagellate Naegleria pringsheimi is acentrosomal and closed (the nuclear membrane does not break down). The large central nucleolus, which occupies about 20% of the nuclear volume, persists throughout the cell cycle. At mitosis, the nucleolus divides and moves to the poles in association with the chromosomes. The structure of the mitotic spindle and its relationship to the nucleolus are unknown. To identify the origin and structure of the mitotic spindle, its relationship to the nucleolus and to further understand the influence of persistent nucleoli on cellular division in acentriolar organisms like Naegleria, three-dimensional reconstructions of the mitotic spindle and nucleolus were carried out using confocal microscopy. Monoclonal antibodies against three different nucleolar regions and α-tubulin were used to image the nucleolus and mitotic spindle. Microtubules were restricted to the nucleolus beginning with the earliest prophase spindle microtubules. Early spindle microtubules were seen as short rods on the surface of the nucleolus. Elongation of the spindle microtubules resulted in a rough cage of microtubules surrounding the nucleolus. At metaphase, the mitotic spindle formed a broad band completely embedded within the nucleolus. The nucleolus separated into two discreet masses connected by a dense band of microtubules as the spindle elongated. At telophase, the distal ends of the mitotic spindle were still completely embedded within the daughter nucleoli. Pixel by pixel comparison of tubulin and nucleolar protein fluorescence showed 70% or more of tubulin co-localized with nucleolar proteins by early prophase. These observations suggest a model in which specific nucleolar binding sites for microtubules allow mitotic spindle formation and attachment. The fact that a significant mass of nucleolar material precedes the chromosomes as the mitotic spindle elongates suggests that spindle elongation drives nucleolar division.

Gravitaxis in the flagellate Euglena gracilis--results from NiZeMi, clinostat and sounding rocket flights.

Science.gov (United States)

Häder, D P

1994-05-01

Many motile microorganisms including flagellates such as the green Euglena gracilis move up and down within the water column and use a number of external clues for their orientation, the most important of which may be light and gravity. The cells use positive phototaxis and negative gravitaxis to move closer to the surface of the water column which for energetic reasons is vital for their survival. However, most phytoplankton organisms cannot tolerate the bright irradiance of unfiltered solar radiation at the surface which also bleaches the photosynthetic pigments, disables the photosynthetic apparatus and impairs phototaxis, gravitaxis and motility in Euglena. Thus, it is not surprising that at higher irradiances negative phototaxis operates antagonistically to the responses described above to guide the cells into deeper water where they are protected from excessive radiation. Phototaxis and gravitaxis are not independent from one another: in a vertically positioned cuvette negative gravitaxis can be "titrated" by light impinging from above and is compensated at about 30 W m-2. While the photoreceptor for phototaxis has been identified in Euglena gracilis biochemically and spectroscopically, the gravireceptor is not yet known. Young cultures of Euglena gracilis show a positive gravitaxis, the ecological signficance of which is not yet understood while older cultures show negative gravitaxis. One hypothesis concerning the nature of graviperception is based on a passive physical process such as an asymmetric distribution of the mass within the cell. However, the observation that short term UV irradiation decreases the precision of negative gravitaxis rather indicates the involvement of an active physiological gravireceptor. Furthermore, some heavy metal ions have been found to change the direction of movement from positive to negative gravitaxis in young cells.

Identification criteria of the rare multi-flagellate Lophomonas blattarum: comparison of different staining techniques.

Science.gov (United States)

Alam-Eldin, Yosra Hussein; Abdulaziz, Amany Mamdouh

2015-09-01

Bronchopulmonary lophomoniasis (BPL) is an emerging disease of potential importance. BPL is presented by non-specific clinical picture and is usually accompanied by immunosuppression. Culture of Lophomonas blattarum is difficult and its molecular diagnosis has not yet been developed. Therefore, microscopic examination of respiratory samples, e.g., bronchoalveolar lavage (BAL) or sputum, is the mainstay of BPL diagnosis. Creola bodies and ciliocytophthoria are two forms of bronchial cells which occur in chest diseases with non-specific clinical picture like that of BPL. Both forms could be misrecognized as multi-flagellates because of their motile cilia in the wet mounts and due to shape variability of L. blattarum in stained smears. The aim of the study is to compare different staining techniques for visualizing L. blattarum to improve the recognition and diagnosis of BPL, to distinguish respiratory epithelial cells from L. blattarum and to decide which stain is recommended in suspected cases of BPL. BAL samples from patients which contain L. blattarum, creola bodies, and ciliocytophthoria were collected then wet mounts were examined. The BAL samples were also stained by Papanicolaou (PAP), Giemsa, hematoxylin and eosin (H & E), trichrome, Gram, and Diff-Quik (DQ) stains. The different staining techniques were compared regarding the stain quality. In wet mounts, the ciliary movement was coordinate and synchronous while the flagellar movement was wavy and leaded to active swimming of L. blattarum. In stained slides, bronchial cells were characterized by the presence of basal nucleus and the terminal bar from which the cilia arise. Trichrome was the best stain in demonstration of cellular details of L. blattarum. H & E, PAP, and Giemsa stains showed good quality of stains. Gram and DQ stains showed only pale hues of L. blattarum. We recommended adding Wheatley's trichrome staining to the differential diagnosis workup of cases of non-specific chest infections

Maximum growth rates and possible life strategies of different bacterioplankton groups in relation to phosphorus availability in a freshwater reservoir

Czech Academy of Sciences Publication Activity Database

Šimek, Karel; Horňák, Karel; Jezbera, Jan; Nedoma, Jiří; Vrba, Jaroslav; Straškrábová, Viera; Macek, Miroslav; Dolan, J. R.; Hahn, M.W.

2006-01-01

Roč. 8, č. 9 (2006), s. 1613-1624 ISSN 1462-2912 R&D Projects: GA ČR(CZ) GA206/05/0007; GA AV ČR(CZ) 1QS600170504 Grant - others:MŠM(CZ) 60076658/01 Institutional research plan: CEZ:AV0Z60170517 Keywords : bacterioplankton community composition * growth of bacteria and flagellates * phosphorus availability * reservoir * top-down and bottom-up control Subject RIV: EE - Microbiology, Virology Impact factor: 4.630, year: 2006

Sulfide assimilation by ectosymbionts of the sessile ciliate, Zoothamnium niveum

DEFF Research Database (Denmark)

Røy, Hans; Vopel, Kay; Huettel, Marcus

2009-01-01

with flow adjusted to in situ velocity. The water motion around the colonies was then characterized by particle tracking velocimetry. This shows that the feather-shaped colony of Z. niveum generates a unidirectional flow of seawater through the colony with no recirculation. The source of the feeding current......We investigated the constraints on sulfide uptake by bacterial ectosymbionts on the marine peritrich ciliate Zoothamnium niveum by a combination of experimental and numerical methods. Protists with symbionts were collected on large blocks of mangrove-peat. The blocks were placed in a flow cell...... bacteria due to Z. niveum's habitat preference and due to the feeding current. Z. niveum is capable of exploiting low concentrations of sulfide in near norm-oxic seawater. This links its otherwise dissimilar habitats and makes it functionally similar to invertebrates with thiotrophic symbionts in filtering...

The friendly bacteria within us Commensal bacteria of the intestine ...

Indian Academy of Sciences (India)

Balance of bacterial species in the gut · Immunosensory detection of intestinal bacteria · Pathogenic bacteria release interleukin-8 from HT-29 cells · Lactobacillus GG prevents the IL-8 release in response to pathogens · Effect of probiotic bacteria on chemokine response of epithelia to pathogens · PCR array studies in colon ...

Big bacteria

DEFF Research Database (Denmark)

Schulz, HN; Jørgensen, BB

2001-01-01

A small number of prokaryotic species have a unique physiology or ecology related to their development of unusually large size. The biomass of bacteria varies over more than 10 orders of magnitude, from the 0.2 mum wide nanobacteria to the largest cells of the colorless sulfur bacteria......, Thiomargarita namibiensis, with a diameter of 750 mum. All bacteria, including those that swim around in the environment, obtain their food molecules by molecular diffusion. Only the fastest and largest swimmers known, Thiovulum majus, are able to significantly increase their food supply by motility...... and by actively creating an advective flow through the entire population. Diffusion limitation generally restricts the maximal size of prokaryotic cells and provides a selective advantage for mum-sized cells at the normally low substrate concentrations in the environment. The largest heterotrophic bacteria...

A rapid phenol toxicity test based on photosynthesis and movement of the freshwater flagellate, Euglena agilis Carter

International Nuclear Information System (INIS)

Kottuparambil, Sreejith; Kim, Youn-Jung; Choi, Hoon; Kim, Mi-Sung; Park, Areum; Park, Jihae; Shin, Woongghi; Han, Taejun

2014-01-01

Highlights: • Rapid phenol toxicity tests (1 h) were developed based on Chl a fluorescence and the movement parameters of Euglena agilis. • Phenol significantly reduced F v /F m of PS II and rETRmax with EC50 values of 8.94 and 4.67 mM, respectively. • Among the movement parameters tested, velocity was the most sensitive biomarker with an EC50 of 3.17 mM. • The EC50 values for F v /F m , motility, and velocity appear to overlap the environmental permissible levels of phenol. - Abstract: Phenol, a monosubstituted aromatic hydrocarbon with various commercial uses, is a major organic constituent in industrial wastewaters. The ecotoxic action of phenol for aquatic environment is well known. In this study, rapid phenol toxicity tests (1 h) were developed based on chlorophyll a (Chl a) fluorescence and the movement parameters of the freshwater flagellate, Euglena agilis Carter. Phenol significantly reduced the maximum quantum yield (F v /F m ) of photosystem II (PS II) and the maximum photosynthetic electron transport rate (rETR max ) with median effective concentration (EC 50 ) values of 8.94 and 4.67 mM, respectively. Phenol reduced the motility and triggered change in the swimming velocity of the test organism. Among the parameters tested, velocity was the most sensitive biomarker with an EC 50 of 3.17 mM. The EC 50 values for F v /F m , motility, and velocity appear to overlap the permitted levels of phenol. In conclusion, the photosynthesis and movement of E. agilis can be fast and sensitive risk assessment parameters for the evaluation of phenol toxicity in municipal and industrial effluents

Big bacteria

DEFF Research Database (Denmark)

Schulz, HN; Jørgensen, BB

2001-01-01

A small number of prokaryotic species have a unique physiology or ecology related to their development of unusually large size. The biomass of bacteria varies over more than 10 orders of magnitude, from the 0.2 mum wide nanobacteria to the largest cells of the colorless sulfur bacteria...... and by actively creating an advective flow through the entire population. Diffusion limitation generally restricts the maximal size of prokaryotic cells and provides a selective advantage for mum-sized cells at the normally low substrate concentrations in the environment. The largest heterotrophic bacteria......, the 80 x 600 mum large Epulopiscium sp. from the gut of tropical fish, are presumably living in a very nutrient-rich medium. Many large bacteria contain numerous inclusions in the cells that reduce the volume of active cytoplasm. The most striking examples of competitive advantage from large cell size...

Halolactibacillus halophilus gen. nov., sp. nov. and Halolactibacillus miurensis sp. nov., halophilic and alkaliphilic marine lactic acid bacteria constituting a phylogenetic lineage in Bacillus rRNA group 1.

Science.gov (United States)

Ishikawa, Morio; Nakajima, Kazuyuki; Itamiya, Yuko; Furukawa, Sayumi; Yamamoto, Yasushi; Yamasato, Kazuhide

2005-11-01

Eleven novel strains of marine-inhabiting lactic acid bacteria that were isolated from living and decaying marine organisms collected from a temperate area of Japan are described. The isolates were motile with peritrichous flagella and non-sporulating. They lacked catalase, quinones and cytochromes. Fermentation products from glucose were lactate, formate, acetate and ethanol. Lactate yield as percentage conversion from glucose was affected by the pH of the fermentation medium: approximately 55 % at the optimal growth pH of 8.0, greater than approximately 70 % at pH 7.0 and less than approximately 30 % at pH 9.0. The molar ratio of the other three products was the same at each cultivation pH, approximately 2 : 1 : 1. Carbohydrates and related compounds were aerobically metabolized to acetate and pyruvate as well as lactate. The isolates were slightly halophilic, highly halotolerant and alkaliphilic. The optimum NaCl concentration for growth was 2.0-3.0 % (w/v), with a range of 0-25.5 %. The optimum pH for growth was 8.0-9.5, with a range of 6.0-10.0. The G+C content of the DNA was 38.5-40.7 mol%. The isolates constituted two genomic species (DNA-DNA relatedness of less than 41 %) each characterized by sugar fermentation profiles. The cell-wall peptidoglycan of both phenotypes contained meso-diaminopimelic acid. The major cellular fatty acids were C(16 : 0) and a-C(13 : 0). Comparative sequence analysis of the 16S rRNA genes revealed that these isolates represent novel species constituting a phylogenetic unit outside the radiation of typical lactic acid bacteria and an independent line of descent within the group composed of the halophilic/halotolerant/alkaliphilic and/or alkalitolerant species in Bacillus rRNA group 1, with 94.8-95.1 % similarity to the genus Paraliobacillus, 93.7-94.1 % to the genus Gracilibacillus and 93.8-94.2 % to Virgibacillus marismortui. On the basis of possession of physiological and biochemical characteristics common to typical lactic acid

Description of Epistylis riograndensis n.sp. (Ciliophora: Peritrichia) found in an artificial lake in Southern Brazil.

Science.gov (United States)

Utz, Laura R P; Farias, Ana Carolina Silva Rodrigues; Freitas, Eduarda Correa; de Araújo, Gabriella Oliveira

2014-10-03

Epistylis riograndensis n. sp., a freshwater peritrich hosting symbiotic algae in its cytoplasm, was collected from an artificial lake, in a Botanical garden in Southern Brazil. Its detailed morphology was investigated using live and silver-stained specimens. The colonial sessile E. riograndensis has elongate zooids measuring, on average, 162 μm in length and 45 μm in width. A single contractile vacuole located near the infundibulum and a C-shaped macronucleus located transversely in the adoral half of the cell were also observed. The oral infraciliature revealed in silver-stained specimens was typical of peritrich ciliates. Three infundibular polykineties consisting of 3 rows of kinetosomes were observed. Molecular analyses of 18s rDNA placed E. riograndensis among other Epistylis species in the Order Vorticellida.

Colonization of overlaying water by bacteria from dry river sediments.

Science.gov (United States)

Fazi, Stefano; Amalfitano, Stefano; Piccini, Claudia; Zoppini, Annamaria; Puddu, Alberto; Pernthaler, Jakob

2008-10-01

We studied the diversity, community composition and activity of the primary microbial colonizers of the water above freshly re-wetted sediments from a temporary river. Dried sediments, collected from Mulargia River (Sardinia, Italy), were covered with sterile freshwater in triplicate microcosms, and changes of the planktonic microbial assemblage were monitored over a 48 h period. During the first 9 h bacterial abundance was low (1.5 x 10(4) cells ml(-1)); it increased to 3.4 x 10(6) cells ml(-1) after 28 h and did not change thereafter. Approximately 20% of bacteria exhibited DNA de novo synthesis already after 9 h of incubation. Changes of the ratios of (3)H-leucine to (3)H-thymidine incorporation rates indicated a shift of growth patterns during the experiment. Extracellular enzyme activity showed a maximum at 48 h with aminopeptidase activity (430.8 +/- 22.6 nmol MCA l(-1) h(-1)) significantly higher than alkaline phosphatase (98.6 +/- 4.3 nmol MUF l(-1) h(-1)). The primary microbial colonizers of the overlaying water - as determined by 16S rRNA gene sequence analysis - were related to at least six different phylogenetic lineages of Bacilli and to Alphaproteobacteria (Brevundimonas spp. and Caulobacter spp.). Large bacterial cells affiliated to one clade of Bacillus sp. were rare in the dried sediments, but constituted the majority of the planktonic microbial assemblage and of cells with detectable DNA-synthesis until 28 h after re-wetting. Their community contribution decreased in parallel with a rise of flagellated and ciliated protists. Estimates based on cell production rates suggested that the rapidly enriched Bacillus sp. suffered disproportionally high loss rates from selective predation, thus favouring the establishment of a more heterogenic assemblage of microbes (consisting of Proteobacteria, Actinobacteria and Cytophaga-Flavobacteria). Our results suggest that the primary microbial colonizers of the water above dried sediments are passively released

A rapid phenol toxicity test based on photosynthesis and movement of the freshwater flagellate, Euglena agilis Carter

Energy Technology Data Exchange (ETDEWEB)

Kottuparambil, Sreejith [Institute of Green Environmental Research Center, Incheon National University, Incheon 406 840 (Korea, Republic of); Kim, Youn-Jung [Institute of Green Environmental Research Center, Incheon National University, Incheon 406 840 (Korea, Republic of); Department of Marine Science, Incheon National University, Incheon 406 840 (Korea, Republic of); Green-Pioneer (Ltd.), Incheon National University, Incheon 406 840 (Korea, Republic of); Choi, Hoon; Kim, Mi-Sung; Park, Areum; Park, Jihae [Institute of Green Environmental Research Center, Incheon National University, Incheon 406 840 (Korea, Republic of); Shin, Woongghi [Department of Biology, Chungnam University, Daejeon 306 764 (Korea, Republic of); Han, Taejun, E-mail: hanalgae@hanmail.net [Institute of Green Environmental Research Center, Incheon National University, Incheon 406 840 (Korea, Republic of); Department of Marine Science, Incheon National University, Incheon 406 840 (Korea, Republic of); Green-Pioneer (Ltd.), Incheon National University, Incheon 406 840 (Korea, Republic of)

2014-10-15

Highlights: • Rapid phenol toxicity tests (1 h) were developed based on Chl a fluorescence and the movement parameters of Euglena agilis. • Phenol significantly reduced F{sub v}/F{sub m} of PS II and rETRmax with EC50 values of 8.94 and 4.67 mM, respectively. • Among the movement parameters tested, velocity was the most sensitive biomarker with an EC50 of 3.17 mM. • The EC50 values for F{sub v}/F{sub m}, motility, and velocity appear to overlap the environmental permissible levels of phenol. - Abstract: Phenol, a monosubstituted aromatic hydrocarbon with various commercial uses, is a major organic constituent in industrial wastewaters. The ecotoxic action of phenol for aquatic environment is well known. In this study, rapid phenol toxicity tests (1 h) were developed based on chlorophyll a (Chl a) fluorescence and the movement parameters of the freshwater flagellate, Euglena agilis Carter. Phenol significantly reduced the maximum quantum yield (F{sub v}/F{sub m}) of photosystem II (PS II) and the maximum photosynthetic electron transport rate (rETR{sub max}) with median effective concentration (EC{sub 50}) values of 8.94 and 4.67 mM, respectively. Phenol reduced the motility and triggered change in the swimming velocity of the test organism. Among the parameters tested, velocity was the most sensitive biomarker with an EC{sub 50} of 3.17 mM. The EC{sub 50} values for F{sub v}/F{sub m}, motility, and velocity appear to overlap the permitted levels of phenol. In conclusion, the photosynthesis and movement of E. agilis can be fast and sensitive risk assessment parameters for the evaluation of phenol toxicity in municipal and industrial effluents.

Bacteria and lignin degradation

Institute of Scientific and Technical Information of China (English)

Jing LI; Hongli YUAN; Jinshui YANG

2009-01-01

Lignin is both the most abundant aromatic (phenolic) polymer and the second most abundant raw material.It is degraded and modified by bacteria in the natural world,and bacteria seem to play a leading role in decomposing lignin in aquatic ecosystems.Lignin-degrading bacteria approach the polymer by mechanisms such as tunneling,erosion,and cavitation.With the advantages of immense environmental adaptability and biochemical versatility,bacteria deserve to be studied for their ligninolytic potential.

Ultrastructure and molecular phylogeny of Calkinsia aureus: cellular identity of a novel clade of deep-sea euglenozoans with epibiotic bacteria

Directory of Open Access Journals (Sweden)

Leander Brian S

2009-01-01

Full Text Available Abstract Background The Euglenozoa is a large group of eukaryotic flagellates with diverse modes of nutrition. The group consists of three main subclades – euglenids, kinetoplastids and diplonemids – that have been confirmed with both molecular phylogenetic analyses and a combination of shared ultrastructural characteristics. Several poorly understood lineages of putative euglenozoans live in anoxic environments, such as Calkinsia aureus, and have yet to be characterized at the molecular and ultrastructural levels. Improved understanding of these lineages is expected to shed considerable light onto the ultrastructure of prokaryote-eukaryote symbioses and the associated cellular innovations found within the Euglenozoa and beyond. Results We collected Calkinsia aureus from core samples taken from the low-oxygen seafloor of the Santa Barbara Basin (580 – 592 m depth, California. These biflagellates were distinctively orange in color and covered with a dense array of elongated epibiotic bacteria. Serial TEM sections through individually prepared cells demonstrated that C. aureus shares derived ultrastructural features with other members of the Euglenozoa (e.g. the same paraxonemal rods, microtubular root system and extrusomes. However, C. aureus also possessed several novel ultrastructural systems, such as modified mitochondria (i.e. hydrogenosome-like, an "extrusomal pocket", a highly organized extracellular matrix beneath epibiotic bacteria and a complex flagellar transition zone. Molecular phylogenies inferred from SSU rDNA sequences demonstrated that C. aureus grouped strongly within the Euglenozoa and with several environmental sequences taken from low-oxygen sediments in various locations around the world. Conclusion Calkinsia aureus possesses all of the synapomorphies for the Euglenozoa, but lacks traits that are specific to any of the three previously recognized euglenozoan subgroups. Molecular phylogenetic analyses of C. aureus

The fecal bacteria

Science.gov (United States)

Sadowsky, Michael J.; Whitman, Richard L.

2011-01-01

The Fecal Bacteria offers a balanced, integrated discussion of fecal bacteria and their presence and ecology in the intestinal tract of mammals, in the environment, and in the food supply. This volume covers their use in examining and assessing water quality in order to offer protection from illnesses related to swimming in or ingesting contaminated water, in addition to discussing their use in engineering considerations of water quality, modeling, monitoring, and regulations. Fecal bacteria are additionally used as indicators of contamination of ready-to-eat foods and fresh produce. The intestinal environment, the microbial community structure of the gut microbiota, and the physiology and genomics of this broad group of microorganisms are explored in the book. With contributions from an internationally recognized group of experts, the book integrates medicine, public health, environmental, and microbiological topics in order to provide a unique, holistic understanding of fecal bacteria. Moreover, it shows how the latest basic science and applied research findings are helping to solve problems and develop effective management strategies. For example, readers will discover how the latest tools and molecular approaches have led to our current understanding of fecal bacteria and enabled us to improve human health and water quality. The Fecal Bacteria is recommended for microbiologists, clinicians, animal scientists, engineers, environmental scientists, food safety experts, water quality managers, and students. It will help them better understand fecal bacteria and use their knowledge to protect human and environmental health. They can also apply many of the techniques and molecular tools discussed in this book to the study of a broad range of microorganisms in a variety of habitats.

Bleach vs. Bacteria

Science.gov (United States)

... Articles | Inside Life Science Home Page Bleach vs. Bacteria By Sharon Reynolds Posted April 2, 2014 Your ... hypochlorous acid to help kill invading microbes, including bacteria. Researchers funded by the National Institutes of Health ...

Potential role of bacteria packaging by protozoa in the persistence and transmission of pathogenic bacteria

OpenAIRE

Denoncourt, Alix M.; Paquet, Valérie E.; Charette, Steve J.

2014-01-01

Many pathogenic bacteria live in close association with protozoa. These unicellular eukaryotic microorganisms are ubiquitous in various environments. A number of protozoa such as amoebae and ciliates ingest pathogenic bacteria, package them usually in membrane structures, and then release them into the environment. Packaged bacteria are more resistant to various stresses and are more apt to survive than free bacteria. New evidence indicates that protozoa and not bacteria control the packaging...

Bacteria-Mineral Interactions on the Surfaces of Metal-Resistant Bacteria

International Nuclear Information System (INIS)

Malkin, A.J.

2010-01-01

The extraordinary ability of indigenous microorganisms, like metal-resistant bacteria, for biotransformation of toxic compounds is of considerable interest for the emerging area of environmental bioremediation. However, the underlying mechanisms by which metal-resistant bacteria transform toxic compounds are currently unknown and await elucidation. The project's objective was to study stress-induced responses of metal-resistant bacteria to environmental changes and chemical stimulants. This project involved a multi-institutional collaboration of our LLNL group with the group of Dr. H.-Y. Holman (Lawrence Berkeley National Laboratory). In this project, we have utilized metal-resistant bacteria Arthrobacter oxydans as a model bacterial system. We have utilized atomic force microscopy (AFM) to visualize for the first time at the nanometer scale formation of stress-induced structures on bacterial surfaces in response to Cr (VI) exposure. We have demonstrated that structure, assembly, and composition of these stress-induced structures are dependent on Cr (VI) concentrations. Our AFM observations of the appearance and development of stress-induced layers on the surfaces of Arthrobacter oxydans bacteria exposed to Cr (VI) were confirmed by Dr. Holman's biochemical, electron microscopy, and synchrotron infrared spectromicroscopy studies. In general, in vitro imaging of live microbial and cellular systems represents one of the most challenging issues in application of AFM. Various approaches for immobilization of bacteria on the substrate for in vitro imaging were tested in this project. Imaging of live bacteria was achieved, however further optimization of experimental methods are needed for high-resolution visualization of the cellular environmental structural dynamics by AFM. This project enhanced the current insight into molecular architecture, structural and environmental variability of bacterial systems. The project partially funded research for two book chapters (1

[Darwin and bacteria].

Science.gov (United States)

Ledermann D, Walter

2009-02-01

As in 2009 the scientific world celebrates two hundreds years from the birthday of Charles Darwin and one hundred and fifty from the publication of The Origin of Species, an analysis of his complete work is performed, looking for any mention of bacteria. But it seems that the great naturahst never took knowledge about its existence, something rather improbable in a time when the discovery of bacteria shook the medical world, or he deliberately ignored them, not finding a place for such microscopic beings into his theory of evolution. But the bacteria badly affected his familiar life, killing scarlet fever one of his children and worsening to death the evolution of tuberculosis of his favourite Annie. Darwin himself could suffer the sickness of Chagas, whose etiological agent has a similar level to bacteria in the scale of evolution.

High genetic diversity and fine-scale spatial structure in the marine flagellate Oxyrrhis marina (Dinophyceae uncovered by microsatellite loci.

Directory of Open Access Journals (Sweden)

Chris D Lowe

2010-12-01

Full Text Available Free-living marine protists are often assumed to be broadly distributed and genetically homogeneous on large spatial scales. However, an increasing application of highly polymorphic genetic markers (e.g., microsatellites has provided evidence for high genetic diversity and population structuring on small spatial scales in many free-living protists. Here we characterise a panel of new microsatellite markers for the common marine flagellate Oxyrrhis marina. Nine microsatellite loci were used to assess genotypic diversity at two spatial scales by genotyping 200 isolates of O. marina from 6 broad geographic regions around Great Britain and Ireland; in one region, a single 2 km shore line was sampled intensively to assess fine-scale genetic diversity. Microsatellite loci resolved between 1-6 and 7-23 distinct alleles per region in the least and most variable loci respectively, with corresponding variation in expected heterozygosities (H(e of 0.00-0.30 and 0.81-0.93. Across the dataset, genotypic diversity was high with 183 genotypes detected from 200 isolates. Bayesian analysis of population structure supported two model populations. One population was distributed across all sampled regions; the other was confined to the intensively sampled shore, and thus two distinct populations co-occurred at this site. Whilst model-based analysis inferred a single UK-wide population, pairwise regional F(ST values indicated weak to moderate population sub-division (0.01-0.12, but no clear correlation between spatial and genetic distance was evident. Data presented in this study highlight extensive genetic diversity for O. marina; however, it remains a substantial challenge to uncover the mechanisms that drive genetic diversity in free-living microorganisms.

Potential role of bacteria packaging by protozoa in the persistence and transmission of pathogenic bacteria

Directory of Open Access Journals (Sweden)

Alix M Denoncourt

2014-05-01

Full Text Available Many pathogenic bacteria live in close association with protozoa. These unicellular eukaryotic microorganisms are ubiquitous in various environments. A number of protozoa such as amoebae and ciliates ingest pathogenic bacteria, package them usually in membrane structures, and then release them into the environment. Packaged bacteria are more resistant to various stresses and are more apt to survive than free bacteria. New evidence indicates that protozoa and not bacteria control the packaging process. It is possible that packaging is more common than suspected and may play a major role in the persistence and transmission of pathogenic bacteria. To confirm the role of packaging in the propagation of infections, it is vital that the molecular mechanisms governing the packaging of bacteria by protozoa be identified as well as elements related to the ecology of this process in order to determine whether packaging acts as a Trojan Horse.

Lipopolysaccharides in diazotrophic bacteria.

Science.gov (United States)

Serrato, Rodrigo V

2014-01-01

Biological nitrogen fixation (BNF) is a process in which the atmospheric nitrogen (N2) is transformed into ammonia (NH3) by a select group of nitrogen-fixing organisms, or diazotrophic bacteria. In order to furnish the biologically useful nitrogen to plants, these bacteria must be in constant molecular communication with their host plants. Some of these molecular plant-microbe interactions are very specific, resulting in a symbiotic relationship between the diazotroph and the host. Others are found between associative diazotrophs and plants, resulting in plant infection and colonization of internal tissues. Independent of the type of ecological interaction, glycans, and glycoconjugates produced by these bacteria play an important role in the molecular communication prior and during colonization. Even though exopolysaccharides (EPS) and lipochitooligosaccharides (LCO) produced by diazotrophic bacteria and released onto the environment have their importance in the microbe-plant interaction, it is the lipopolysaccharides (LPS), anchored on the external membrane of these bacteria, that mediates the direct contact of the diazotroph with the host cells. These molecules are extremely variable among the several species of nitrogen fixing-bacteria, and there are evidences of the mechanisms of infection being closely related to their structure.

Cable Bacteria in Freshwater Sediments

DEFF Research Database (Denmark)

Risgaard-Petersen, Nils; Kristiansen, Michael; Frederiksen, Rasmus

2015-01-01

In marine sediments cathodic oxygen reduction at the sediment surface can be coupled to anodic sulfide oxidation in deeper anoxic layers through electrical currents mediated by filamentous, multicellular bacteria of the Desulfobulbaceae family, the so-called cable bacteria. Until now, cable...... bacteria have only been reported from marine environments. In this study, we demonstrate that cable bacteria also occur in freshwater sediments. In a first step, homogenized sediment collected from the freshwater stream Giber Å, Denmark, was incubated in the laboratory. After 2 weeks, pH signatures...... marine cable bacteria, with the genus Desulfobulbus as the closest cultured lineage. The results of the present study indicate that electric currents mediated by cable bacteria could be important for the biogeochemistry in many more environments than anticipated thus far and suggest a common evolutionary...

Population dynamics of active and total ciliate populations in arable soil amended with wheat

DEFF Research Database (Denmark)

Ekelund, F.; Frederiksen, Helle B.; Ronn, R.

2002-01-01

of the population may be encysted. The factors governing the dynamics of active and encysted cells in the soil are not well understood. Our objective was to determine the dynamics of active and encysted populations of ciliates during the decomposition of freshly added organic material. We monitored, in soil...... microcosms, the active and total populations of ciliates, their potential prey (bacteria and small protozoa), their potential competitors (amoebae, flagellates, and nematodes), and their potential predators (nematodes). We sampled with short time intervals (2 to 6 days) and generated a data set, suitable...

Radiation-resistant asporogenic bacteria

Energy Technology Data Exchange (ETDEWEB)

Yano, K [Tokyo Univ. (Japan). Faculty of Agriculture

1975-09-01

This paper reports the biological and ecological examinations on the radiation-resistant asporogenic bacteria (mainly concerning Micrococcus radiodurans). Radiation-resistant asporogenic bacteria were isolated from the irradiated areas of the natural world as well as from the general areas and from the Rn waters in the Misasa hot spring. The acquiring of the tolerance to radiation in bacteria was also examined. In addition, the future problems of microbiological treatment with irradiation were mentioned.

Radiation-resistant asporogenic bacteria

International Nuclear Information System (INIS)

Yano, Keiji

1975-01-01

This paper reports the biological and ecological examinations on the radiation-resistant asporogenic bacteria (mainly concerning Micrococcus radiodurans). Radiation-resistant asporogenic bacteria were isolated from the irradiated areas of the natural world as well as from the general areas and from the Rn waters in the Misasa hot spring. The acquiring of the tolerance to radiation in bacteria was also examined. In addition, the future problems of microbiological treatment with irradiation were mentioned. (Tsukamoto, Y.)

Immunomodulatory properties of probiotic bacteria

DEFF Research Database (Denmark)

Fink, Lisbeth Nielsen

2007-01-01

Certain lactic acid bacteria (LAB) are part of the commensal intestinal flora and considered beneficial for health, as they compete with pathogens for adhesion sites in the intestine and ferment otherwise indigestible compounds. Another important property of these so-called probiotic bacteria...... with bacteria, and the cytokine pattern induced by specific bacteria resembled the pattern induced in MoDC, except for TNF-alpha and IL-6, which were induced in response to different bacteria in blood DC/monocytes and monocyte-derived DC. Autologous NK cells produced IFN-gamma when cultured with blood DC......, monocytes and monocyte-derived DC and IL-12-inducing bacteria, whereas only DC induced IFN-gamma production in allogeneic T cells. In vitro-generated DC is a commonly used model of tissue DC, but they differ in certain aspects from intestinal DC, which are in direct contact with the intestinal microbiota...

Bacteria-surface interactions.

Science.gov (United States)

Tuson, Hannah H; Weibel, Douglas B

2013-05-14

The interaction of bacteria with surfaces has important implications in a range of areas, including bioenergy, biofouling, biofilm formation, and the infection of plants and animals. Many of the interactions of bacteria with surfaces produce changes in the expression of genes that influence cell morphology and behavior, including genes essential for motility and surface attachment. Despite the attention that these phenotypes have garnered, the bacterial systems used for sensing and responding to surfaces are still not well understood. An understanding of these mechanisms will guide the development of new classes of materials that inhibit and promote cell growth, and complement studies of the physiology of bacteria in contact with surfaces. Recent studies from a range of fields in science and engineering are poised to guide future investigations in this area. This review summarizes recent studies on bacteria-surface interactions, discusses mechanisms of surface sensing and consequences of cell attachment, provides an overview of surfaces that have been used in bacterial studies, and highlights unanswered questions in this field.

Genomics of Probiotic Bacteria

Science.gov (United States)

O'Flaherty, Sarah; Goh, Yong Jun; Klaenhammer, Todd R.

Probiotic bacteria from the Lactobacillus and Bifidobacterium species belong to the Firmicutes and the Actinobacteria phylum, respectively. Lactobacilli are members of the lactic acid bacteria (LAB) group, a broadly defined family of microorganisms that ferment various hexoses into primarily lactic acid. Lactobacilli are typically low G + C gram-positive species which are phylogenetically diverse, with over 100 species documented to date. Bifidobacteria are heterofermentative, high G + C content bacteria with about 30 species of bifidobacteria described to date.

Trypanosoma cruzi alkaline 2-DE: Optimization and application to comparative proteome analysis of flagellate life stages

Directory of Open Access Journals (Sweden)

Santana Jaime M

2008-09-01

Full Text Available Abstract Background Trypanosoma cruzi, a flagellate protozoan, is the etiological agent of Chagas disease, a chronic illness that causes irreversible damage to heart and digestive tract in humans. Previous 2-DE analyses of T. cruzi proteome have not focused on basic proteins, possibly because of inherent difficulties for optimizing 2-DE in the alkaline pH range. However, T. cruzi wide pH range 2-DE gels have shown few visible spots in the alkaline region, indicating that the parasite either did not have an appreciable amount of alkaline proteins or that these proteins were underrepresented in the 2-DE gels. Results Different IEF conditions using 6–11 pH gradient strips were tested for separation of T. cruzi alkaline proteins. The optimized methodology described here was performed using anodic "paper bridge" sample loading supplemented by increased concentration of DTT and Triton X-100 on Multiphor II (GE Healthcare equipment and an electrode pad embedded in DTT- containing solution near the cathode in order to avoid depletion of reducing agent during IEF. Landmark proteins were identified by peptide mass fingerprinting allowing the production of an epimastigote 2-DE map. Most identified proteins corresponded to metabolic enzymes, especially those related to amino acid metabolism. The optimized 2-DE protocol was applied in combination with the "two-in-one gel" method to verify the relative expression of the identified proteins between samples from epimastigote and trypomastigote life stages. Conclusion High resolution 2-DE gels of T. cruzi life forms were achieved using the optimized methodology and a partial epimastigote alkaline 2-DE map was built. Among 700 protein spots detected, 422 were alkaline with a pI above 7.0. The "two-in-one gel" method simplified the comparative analysis between T. cruzi life stages since it minimized variations in spot migration and silver-stained spot volumes. The comparative data were in agreement with

Nitrogen-fixing methane-utilizing bacteria

NARCIS (Netherlands)

Bont, de J.A.M.

1976-01-01

Methane occurs abundantly in nature. In the presence of oxygen this gas may be metabolized by bacteria that are able to use it as carbon and energy source. Several types of bacteria involved in the oxidation of methane have been described in literature. Methane-utilizing bacteria have in

Pathogenic Assay of Probiotic Bacteria Producing Proteolytic Enzymes as Bioremediation Bacteria Against Vannamei Shrimp Larvae (Litopenaeus vannamei)

OpenAIRE

Wilis Ari Setyati; Muhammad Zainuddin; Person Pesona Renta

2017-01-01

Application of bacteria in bioremediation of shrimp culture ponds is one of the methods used to clean internal pollutants. This study aimed to evaluate the pathogenicity of extracellular proteolytic enzyme produced by the probiotic bacteria as bioremediation bacteria on vannamei shrimp larvae culture. There were five probiotic bacteria, which were successfully isolated from the sediments served as substrate in mangrove area. The isolated bacteria were coded in number as 13, 19, 30, 33, and 36...

Cadmium resistance of endophytic bacteria and rizosféricas bacteria isolated from Oriza sativa in Colombia

Directory of Open Access Journals (Sweden)

Nataly Ayubb T

2017-12-01

Full Text Available The present study had as objective to evaluate in vitro the resistance of endophytic bacteria and rizospheric bacteria to different concentrations of Cadmium.This bacteria were isolated fron different tissues of commercial rice varieties and from bacteria isolated from the rhizosphere in rice plantations of the Nechí (Antioquía and Achí (Bolivar.  Plant growth promotion was evaluated in vitro by nitrogen fixation, phosphate solubilization and siderophores production of endophytic bacteria. Of each tissue isolated from rice plants was carried out isolation in culture medium for endophytic bacteria, and the soil samples were serially diluted in peptone water. Each sample was determined the population density by counting in CFU / g of tissue and morphotypes were separated by shape, color, size and appearance in culture media. Significant differences were observed for density population of bacteria with respect to tissue, with higher values in root (4x1011 g/root, followed of the stem (3x1010g/etem, leaf (5x109 g/ leaf, flag leaf (3x109 g/ flag leaf and with less density in panicle (4x108 g/panicle. The results of the identification with kit API were confirmed the presence of endophytic bacteria Burkholderia cepaceae and rizospheric bacteria Pseudomona fluorescens With the ability to tolerate different concentrations of Cd, fix nitrogen, solubilize phosphates and produce siderophores.

Method of Detecting Coliform Bacteria and Escherichia Coli Bacteria from Reflected Light

Science.gov (United States)

Vincent, Robert (Inventor)

2013-01-01

The present invention relates to a method of detecting coliform bacteria in water from reflected light and a method of detecting Eschericha Coli bacteria in water from reflected light, and also includes devices for the measurement, calculation and transmission of data relating to that method.

Amoebae and other protozoa in material samples from moisture-damaged buildings

International Nuclear Information System (INIS)

Yli-Pirilae, T.; Kusnetsov, Jaana; Haatainen, Susanna; Haenninen, Marja; Jalava, Pasi; Reiman, Marjut; Seuri, Markku; Hirvonen, Maija-Riitta; Nevalainen, Aino

2004-01-01

Mold growth in buildings has been shown to be associated with adverse health effects. The fungal and bacterial growth on moistened building materials has been studied, but little attention has been paid to the other organisms spawning in the damaged materials. We examined moist building materials for protozoa, concentrating on amoebae. Material samples (n=124) from moisture-damaged buildings were analyzed for amoebae, fungi, and bacteria. Amoebae were detected in 22% of the samples, and they were found to favor cooccurrence with bacteria and the fungi Acremonium spp., Aspergillus versicolor, Chaetomium spp., and Trichoderma spp. In addition, 11 seriously damaged samples were screened for other protozoa. Ciliates and flagellates were found in almost every sample analyzed. Amoebae are known to host pathogenic bacteria, such as chlamydiae, legionellae, and mycobacteria and they may have a role in the complex of exposure that contributes to the health effects associated with moisture damage in buildings

Motility of electric cable bacteria

DEFF Research Database (Denmark)

Bjerg, Jesper Tataru; Damgaard, Lars Riis; Holm, Simon Agner

2016-01-01

Cable bacteria are filamentous bacteria that electrically couple sulfide oxidation and oxygen reduction at centimeter distances, and observations in sediment environments have suggested that they are motile. By time-lapse microscopy, we found that cable bacteria used gliding motility on surfaces...... with a highly variable speed of 0.50.3 ms1 (meanstandard deviation) and time between reversals of 155108 s. They frequently moved forward in loops, and formation of twisted loops revealed helical rotation of the filaments. Cable bacteria responded to chemical gradients in their environment, and around the oxic......-anoxic interface, they curled and piled up, with straight parts connecting back to the source of sulfide. Thus, it appears that motility serves the cable bacteria in establishing and keeping optimal connections between their distant electron donor and acceptors in a dynamic sediment environment....

Fermentation of D-Tagatose by Human Intestinal Bacteria and Dairy Lactic Acid Bacteria

OpenAIRE

Bertelsen, Hans; Andersen, Hans; Tvede, Michael

2011-01-01

A number of 174 normal or pathogenic human enteric bacteria and dairy lactic acid bacteria were screened for D-tagatose fermentation by incubation for 48 hours. Selection criteria for fermentation employed included a drop in pH below 5.5 and a distance to controls of more than 0.5. Only a few of the normal occurring enteric human bacteria were able to ferment D-tagatose, among those Enterococcus faecalis, Enterococcus faecium and Lactobacillus strains. D-Tagatose fermentation seems to be comm...

METHODS FOR DETECTING BACTERIA USING POLYMER MATERIALS

NARCIS (Netherlands)

Van Grinsven Bart Robert, Nicolaas; Cleij, Thomas

2017-01-01

A method for characterizing bacteria includes passing a liquid containing an analyte comprising a first bacteria and a second bacteria over and in contact with a polymer material on a substrate. The polymer material is formulated to bind to the first bacteria, and the first bacteria binds to the

Sulfur metabolism in phototrophic sulfur bacteria

DEFF Research Database (Denmark)

Frigaard, Niels-Ulrik; Dahl, Christiane

2008-01-01

Phototrophic sulfur bacteria are characterized by oxidizing various inorganic sulfur compounds for use as electron donors in carbon dioxide fixation during anoxygenic photosynthetic growth. These bacteria are divided into the purple sulfur bacteria (PSB) and the green sulfur bacteria (GSB......). They utilize various combinations of sulfide, elemental sulfur, and thiosulfate and sometimes also ferrous iron and hydrogen as electron donors. This review focuses on the dissimilatory and assimilatory metabolism of inorganic sulfur compounds in these bacteria and also briefly discusses these metabolisms...... in other types of anoxygenic phototrophic bacteria. The biochemistry and genetics of sulfur compound oxidation in PSB and GSB are described in detail. A variety of enzymes catalyzing sulfur oxidation reactions have been isolated from GSB and PSB (especially Allochromatium vinosum, a representative...

A new protocol for the detection of Enterobacter sakazakii applied to environmental samples

NARCIS (Netherlands)

Kandhai, M.C.; Reij, M.W.; Puyvelde, van K.; Guillaume-Gentil, O.; Beumer, R.R.; Schothorst, van M.

2004-01-01

Enterobacter sakazakii is a motile, peritrichous, gram-negative rod that was previously known as a yellow pigmented Enterobacter cloacae. It is documented as a rare cause of outbreaks and sporadic cases of life-threatening neonatal meningitis, necrotizing enterocolitis, and sepsis. E. sakazakii has

Isolation and Presumptive Identification of Adherent Epithelial Bacteria (“Epimural” Bacteria) from the Ovine Rumen Wall

OpenAIRE

Mead, Lorna J.; Jones, G. A.

1981-01-01

One hundred sixty-one strains of adherent bacteria were isolated under anaerobic conditions from four sites on the rumen epithelial surface of sheep fed hay or a hay-grain ration. Before isolation of bacteria, rumen tissue was washed six times in an anaerobic dilution solution, and viable bacteria suspended in the washings were counted. Calculation indicated that unattached bacteria would have been removed from the tissue by this procedure, but a slow and progressive release of attached bacte...

Re-engineering bacteria for ethanol production

Science.gov (United States)

Yomano, Lorraine P; York, Sean W; Zhou, Shengde; Shanmugam, Keelnatham; Ingram, Lonnie O

2014-05-06

The invention provides recombinant bacteria, which comprise a full complement of heterologous ethanol production genes. Expression of the full complement of heterologous ethanol production genes causes the recombinant bacteria to produce ethanol as the primary fermentation product when grown in mineral salts medium, without the addition of complex nutrients. Methods for producing the recombinant bacteria and methods for producing ethanol using the recombinant bacteria are also disclosed.

Oligotrophic bacteria isolated from clinical materials.

OpenAIRE

Tada, Y; Ihmori, M; Yamaguchi, J

1995-01-01

Oligotrophic bacteria (oligotrophs) are microorganisms that grow in extremely nutritionally deficient conditions in which the concentrations of organic substances are low. Many oligotrophic bacteria were isolated from clinical materials including urine, sputum, swabbings of the throat, vaginal discharges, and others. Seventy-seven strains of oligotrophic bacteria from 871 samples of clinical material were isolated. A relatively higher frequency of isolation of oligotrophic bacteria was shown ...

Seeing green bacteria in a new light: genomics-enabled studies of the photosynthetic apparatus in green sulfur bacteria and filamentous anoxygenic phototrophic bacteria

DEFF Research Database (Denmark)

Frigaard, Niels-Ulrik; Bryant, Donald A

2004-01-01

Based upon their photosynthetic nature and the presence of a unique light-harvesting antenna structure, the chlorosome, the photosynthetic green bacteria are defined as a distinctive group in the Bacteria. However, members of the two taxa that comprise this group, the green sulfur bacteria...... (Chlorobi) and the filamentous anoxygenic phototrophic bacteria ("Chloroflexales"), are otherwise quite different, both physiologically and phylogenetically. This review summarizes how genome sequence information facilitated studies of the biosynthesis and function of the photosynthetic apparatus...... a and carotenoid biosynthesis enzymes, gene cluster analysis in Cfx. aurantiacus, and gene inactivation studies in Chl. tepidum. Based on these results, BChl a and BChl c biosynthesis is similar in the two organisms, whereas carotenoid biosynthesis differs significantly. In agreement with its facultative anaerobic...

Differential response of marine flagellate communities to prokaryotic food quality

Science.gov (United States)

De Corte, D.; Paredes, G.; Sintes, E.; Herndl, G. J.

2016-02-01

Marine prokaryotes play a major role in the biogeochemical cycles. The main predators of prokaryotes are heterotrophic nanoflagellates (HNF). HNF are thus a major link connecting dissolved organic material through prokaryotic grazing to the higher trophic levels. However, little is known about the grazing specificity of HNF on specific prokaryotic taxa. Bacterial and archaeal microbes may have different nutritive values for the HNF communities, thus affecting growth rates and community composition of HNFs. In this study we investigated the influence of prey food quality on Cafeteria roenbergensis and on a natural HNF community isolated in the northern Adriatic Sea. Two Nitrosopumilus maritimus-related strains isolated from the northern Adriatic Sea (Nitrosopumilus adriaticus, Nitrosopumilus piranensis), two Nitrosococcus strains and two fast growing marine Bacteria (Pseudomonas marina and Marinobacter algicola) were fed to the HNFs. The two fast growing bacterial strains resulted in high growth rates of Cafeteria roenbergensis and the mixed HNF community, while the two Nitrosococcus strains did not. Cafeteria roenbergensis fed on N. adriaticus but it did not graze N. piranensis, suggesting that the subtle metabolic and physiological differences between these two closely related thaumarchaeal strains affect the grazing pressure to which they are exposed. Our study also indicates that prokaryotic community composition influences the composition of the HNF community.

How honey kills bacteria

NARCIS (Netherlands)

Kwakman, Paulus H. S.; te Velde, Anje A.; de Boer, Leonie; Speijer, Dave; Vandenbroucke-Grauls, Christina M. J. E.; Zaat, Sebastian A. J.

2010-01-01

With the rise in prevalence of antibiotic-resistant bacteria, honey is increasingly valued for its antibacterial activity. To characterize all bactericidal factors in a medical-grade honey, we used a novel approach of successive neutralization of individual honey bactericidal factors. All bacteria

Pathogenic Assay of Probiotic Bacteria Producing Proteolytic Enzymes as Bioremediation Bacteria Against Vannamei Shrimp Larvae (Litopenaeus vannamei

Directory of Open Access Journals (Sweden)

Wilis Ari Setyati

2017-06-01

Full Text Available Application of bacteria in bioremediation of shrimp culture ponds is one of the methods used to clean internal pollutants. This study aimed to evaluate the pathogenicity of extracellular proteolytic enzyme produced by the probiotic bacteria as bioremediation bacteria on vannamei shrimp larvae culture. There were five probiotic bacteria, which were successfully isolated from the sediments served as substrate in mangrove area. The isolated bacteria were coded in number as 13, 19, 30, 33, and 36. Pathogenic bacteria Vibrio harveyi was used as positive control. Pathogenic assay was carried out in two different bacterial concentrations, i.e. 10⁸ and 10⁶ cells.mL-1. The results showed that the lowest survival rate (SR of shrimp larvae in positive control V. harveyi was 53 and 65%. Whereas isolates with the highest SR value (100% were obtained from bacteria coded as 13 and 30. Isolates no. 19, 33 and 36 had SR of more than 90%. Total plate count (TPC data showed that the bacteria increased significantly at the end of the study with an average increase value of 24%. The smallest TPC value was shown by bacterial isolate no. 19, while the largest was obtained from the isolate no. 13. These results suggest that all probiotic bacteria were not pathogenic to the vannamei shrimp larvae.   Keywords: aquaculture, shrimp, bioremediation, pathogenesis, vibrio.

Effect of air pollution on the total bacteria and pathogenic bacteria in different sizes of particulate matter.

Science.gov (United States)

Liu, Huan; Zhang, Xu; Zhang, Hao; Yao, Xiangwu; Zhou, Meng; Wang, Jiaqi; He, Zhanfei; Zhang, Huihui; Lou, Liping; Mao, Weihua; Zheng, Ping; Hu, Baolan

2018-02-01

In recent years, air pollution events have occurred frequently in China during the winter. Most studies have focused on the physical and chemical composition of polluted air. Some studies have examined the bacterial bioaerosols both indoors and outdoors. But few studies have focused on the relationship between air pollution and bacteria, especially pathogenic bacteria. Airborne PM samples with different diameters and different air quality index values were collected in Hangzhou, China from December 2014 to January 2015. High-throughput sequencing of 16S rRNA was used to categorize the airborne bacteria. Based on the NCBI database, the "Human Pathogen Database" was established, which is related to human health. Among all the PM samples, the diversity and concentration of total bacteria were lowest in the moderately or heavily polluted air. However, in the PM2.5 and PM10 samples, the relative abundances of pathogenic bacteria were highest in the heavily and moderately polluted air respectively. Considering the PM samples with different particle sizes, the diversities of total bacteria and the proportion of pathogenic bacteria in the PM10 samples were different from those in the PM2.5 and TSP samples. The composition of PM samples with different sizes range may be responsible for the variances. The relative humidity, carbon monoxide and ozone concentrations were the main factors, which affected the diversity of total bacteria and the proportion of pathogenic bacteria. Among the different environmental samples, the compositions of the total bacteria were very similar in all the airborne PM samples, but different from those in the water, surface soil, and ground dust samples. Which may be attributed to that the long-distance transport of the airflow may influence the composition of the airborne bacteria. This study of the pathogenic bacteria in airborne PM samples can provide a reference for environmental and public health researchers. Copyright © 2017 Elsevier Ltd

Antibiotics from predatory bacteria

Directory of Open Access Journals (Sweden)

Juliane Korp

2016-03-01

Full Text Available Bacteria, which prey on other microorganisms, are commonly found in the environment. While some of these organisms act as solitary hunters, others band together in large consortia before they attack their prey. Anecdotal reports suggest that bacteria practicing such a wolfpack strategy utilize antibiotics as predatory weapons. Consistent with this hypothesis, genome sequencing revealed that these micropredators possess impressive capacities for natural product biosynthesis. Here, we will present the results from recent chemical investigations of this bacterial group, compare the biosynthetic potential with that of non-predatory bacteria and discuss the link between predation and secondary metabolism.

Beer spoilage bacteria and hop resistance

NARCIS (Netherlands)

Sakamoto, K; Konings, WN

2003-01-01

For brewing industry, beer spoilage bacteria have been problematic for centuries. They include some lactic acid bacteria such as Lactobacillus brevis, Lactobacillus lindneri and Pediococcus damnosus, and some Gram-negative bacteria such as Pectinatus cerevisiiphilus, Pectinatus frisingensis and

Contrasting response to nutrient manipulation in Arctic mesocosms are reproduced by a minimum microbial food web model.

Science.gov (United States)

Larsen, Aud; Egge, Jorun K; Nejstgaard, Jens C; Di Capua, Iole; Thyrhaug, Runar; Bratbak, Gunnar; Thingstad, T Frede

2015-03-01

A minimum mathematical model of the marine pelagic microbial food web has previously shown to be able to reproduce central aspects of observed system response to different bottom-up manipulations in a mesocosm experiment Microbial Ecosystem Dynamics (MEDEA) in Danish waters. In this study, we apply this model to two mesocosm experiments (Polar Aquatic Microbial Ecology (PAME)-I and PAME-II) conducted at the Arctic location Kongsfjorden, Svalbard. The different responses of the microbial community to similar nutrient manipulation in the three mesocosm experiments may be described as diatom-dominated (MEDEA), bacteria-dominated (PAME-I), and flagellated-dominated (PAME-II). When allowing ciliates to be able to feed on small diatoms, the model describing the diatom-dominated MEDEA experiment give a bacteria-dominated response as observed in PAME I in which the diatom community comprised almost exclusively small-sized cells. Introducing a high initial mesozooplankton stock as observed in PAME-II, the model gives a flagellate-dominated response in accordance with the observed response also of this experiment. The ability of the model originally developed for temperate waters to reproduce population dynamics in a 10°C colder Arctic fjord, does not support the existence of important shifts in population balances over this temperature range. Rather, it suggests a quite resilient microbial food web when adapted to in situ temperature. The sensitivity of the model response to its mesozooplankton component suggests, however, that the seasonal vertical migration of Arctic copepods may be a strong forcing factor on Arctic microbial food webs.

Temporal variability of the microbial food web (viruses to ciliates under the influence of the Black Sea Water inflow (N. Aegean, E. Mediterranean

Directory of Open Access Journals (Sweden)

A. GIANNAKOUROU

2014-12-01

Full Text Available Τhe entire pelagic microbial food web was studied during the winter-spring period in the frontal area of the North Aegean Sea. Abundance of viruses, heterotrophic bacteria, cyanobacteria, auto- and hetero-trophic flagellates, and ciliates, as well as bacterial production, were measured at three stations (MD1, MD2, MD3 situated along a N-S transect between the area directly influenced by the inflowing Black Sea water and the area covered by the Levantine water. Samples were collected in December 2009, and January, March, April, and May 2011. Station MD1 exhibited the highest values of abundance and integrated biomass of all microbial groups and bacterial production during all months, and MD3 the lowest. Bacteria dominated the total integrated biomass at all stations and months, followed by cyanobacteria, auto-, hetero-trophic flagellates and ciliates. On a temporal scale, the microbial food web was less important in March as all microbial parameters at all stations showed the lowest values. After the phytoplankton bloom in March, the heterotrophic part of the microbial food web (mainly strongly increased, though the intensity of the phenomenon was diminished from North to South. Pico-sized plankton was found to be heterotrophic whereas nanoplankton was autotrophic. It seems that the influence of the Black Sea water on station MD1, permanent throughout the study period of early winter to late spring, was reflected in all microbial populations studied, and produced a more productive pelagic food web system, with potential consequences for the upper trophic levels.

Human body may produce bacteria.

Science.gov (United States)

Salerian, Alen J

2017-06-01

"Human body may produce bacteria" proposes that human body may produce bacteria and represent an independent source of infections contrary to the current paradigm of infectious disorders proposed by Louis Pasteur in 1880. The following observations are consistent with this hypothesis: A. Bidirectional transformations of both living and nonliving things have been commonly observed in nature. B. Complex multicellular organisms harbor the necessary properties to produce bacteria (water, nitrogen and oxygen). C. Physical laws suggest any previously observed phenomenon or action will occur again (life began on earth; a non living thing). D. Animal muscle cells may generate energy (fermentation). E. Sterilized food products (i.e. boiled eggs), may produce bacteria and fungus under special conditions and without any exposure to foreign living cells. "Human body may produce bacteria" may challenge the current medical paradigm that views human infectious disorders as the exclusive causative byproducts of invading foreign cells. It may also introduce new avenues to treat infectious disorders. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effects of Ethanolic Ferolagu angulata Extract on Pathogenic Gastrointestinal Bacteria and Probiotic Bacteria in Skimmed Milk Medium

Directory of Open Access Journals (Sweden)

Reza Naghiha

2016-12-01

Full Text Available Background:    Due to excessive consumption of synthetic drugs, drug resistance rate of pathogenic bacteria is increasing and there is an ever-increasing need to find new safe compounds to tackle this problem. This study was conducted to investigate the consequences of chavill extract on the growth and viability of gastrointestinal pathogenic bacterium and probiotics bacteria. Methods:    The experiment contained three levels of the chavill extract concentrations (0, 1 and 3% which were added to the milk free fat in accompany with three probiotic bacteria (Lactobacillus acidophilus, Lactobacillus casei and lactobacillus plantaram and a pathogenic gastrointestinal bacterium (Salmonella typhimurium. Bacterial inoculums (1×107 CFU/ml with different concentrations of chavill extract were added to skimmed milk medium and bacteria growth were enumerated. Results:  The concentration of 1% chavill extract significantly increased the total count of probiotic bacteria compared to the control group, while the number of pathogenic bacteria was decreased. At 3% chavill extract the growth of Lactobacillus acidophilus and Lactobacillus plantaram were increased. On the other hand, it prevented the growth of Salmonella typhimurium Conclusion:   Chavill extracts would play as an alternative to antibiotics in pharmacological studies to decreases harmful bacteria and increase probiotic bacteria.

Current strategies for improving food bacteria

NARCIS (Netherlands)

Kuipers, O P; Buist, Girbe; Kok, Jan

2000-01-01

Novel concepts and methodologies are emerging that hold great promise for the directed improvement of food-related bacteria, specifically lactic acid bacteria. Also, the battle against food spoilage and pathogenic bacteria can now be fought more effectively. Here we describe recent advances in

[Unique properties of highly radioresistant bacteria].

Science.gov (United States)

Romanovskaia, V A; Rokitko, P V; Malashenko, Iu R

2000-01-01

In connection with the Chernobyl Nuclear Power Plant (ChNPP) accident and the negative ecological after-effects for biota in this zone the interest has arisen to radioresistant bacteria, as to the most dynamic model of the given ecosystem, and to mechanisms which provide resistance of bacteria to ionizing radiation. The analysis of published data has shown that the radioresistant bacteria are not interrelated taxonomically and phylogenetically. The extreme radioresistant bacteria are represented by the Deinococcus species, which form a group phylogenetically close to the line Thermus-Meiothermus. Other radioresistant bacteria are the representatives of the genera Rubrobacter, Methylobacterium, Kocuria, Bacillus and some archebacteria. Data on natural habitats, of radioresistant bacteria are not numerous. In a number of cases it is difficult to distinguish their natural habitats, as they were isolated from the samples which were previously exposed to X-ray or gamma-irradiation, or from the ecosystems with the naturally raised radioactivity. To understand the strategy of survival of radioresistant bacteria, we briefly reviewed the mechanism of action of various species of radiation on cells and macromolecules; physiological signs of the cell damage caused by radiation; mechanisms eliminating (repairing) these damages. More details on mechanisms of the DNA repair in D. radiodurans are described. The extreme resistance of D. radiodurans to the DNA damaging factors is defined by 1) repair mechanisms which fundamentally differ from those in other procaryotes; 2) ability to increase the efficiency of a standard set of the DNA repairing proteins. Literary and own data on the effect of radiation on survival of various groups of bacteria in natural ecosystems are summarized. The ecological consequences of the ChNPP accident for soil bacteria in this region were estimated. The reduction of the number of soil bacteria and recession of microbial diversity under the effect of

The vitamin B requirement of Phaeocystis globosa (Prymnesiophyceae)

NARCIS (Netherlands)

Peperzak, L; Gieskes, WWC; Duin, R; Colijn, F

In batch cultures of flagellates and non-flagellate cells of Phaeocystis globosa, the biomass yield was significantly enhanced by the addition of a mixture of the vitamins thiamine (B1), cyanocobalamin (B12) and biotin (H). A bioassay with B1 and B12 using the non-flagellate cells of P.globosa

Bactericide for sulfate-reducing bacteria

Energy Technology Data Exchange (ETDEWEB)

Shklyar, T F; Anoshina, G M; Blokhin, V Ye; Kisarrev, Ye L; Novikovsa, G M

1981-01-01

The aim of the invention is to find a bactericide for sulfate-reducing bacteria of oil fields in Western Siberia in order to suppress the biocorrosive activity on oil industry equipment. This goal is achieved by using M-nitroacetanylide as the bactericide of sulfate-reducing bacteria. This agent suppresses the activity of a stored culture of sulfate-reducing bacteria that comes from industrial waste waters injection wells of the Smotlor oil field.

Mycorrhiza helper bacteria

Energy Technology Data Exchange (ETDEWEB)

Deveau, Aurelie [French National Insitute for Agricultural Research (INRA); Labbe, Jessy [ORNL

2016-10-01

This chapter focuses on the Mycorrhiza Helper Bacteria (MHB), a generic name given to bacteria which stimulate the formation of mycorrhizal symbiosis. By extension, some bacterial strains that positively impact the functioning of mycorrhizal symbiosis are also called MHB. These bacteria have applicative interests, as they indirectly improve the health and growth of tree seedlings. MHB are not restricted to a specific type of ecosystem, but are rather generalist in the way that they associate with both herbaceous and woody mycorrhizal plants from boreal, temperate, arid and tropical ecosystems. However, understanding the molecular mechanisms and their specificities will help us to know more about the ecology of the MHB. The process of acquisition varies between fungal species; while ectomycorrhizal fungi most probably recurrently acquire them from the environment, the association between bacterial endosymbionts and Glomeromycota probably dates back to very ancient times, and has since been vertically transmitted.

Horizontal gene transfer between bacteria.

Science.gov (United States)

Heuer, Holger; Smalla, Kornelia

2007-01-01

Horizontal gene transfer (HGT) refers to the acquisition of foreign genes by organisms. The occurrence of HGT among bacteria in the environment is assumed to have implications in the risk assessment of genetically modified bacteria which are released into the environment. First, introduced genetic sequences from a genetically modified bacterium could be transferred to indigenous micro-organisms and alter their genome and subsequently their ecological niche. Second, the genetically modified bacterium released into the environment might capture mobile genetic elements (MGE) from indigenous micro-organisms which could extend its ecological potential. Thus, for a risk assessment it is important to understand the extent of HGT and genome plasticity of bacteria in the environment. This review summarizes the present state of knowledge on HGT between bacteria as a crucial mechanism contributing to bacterial adaptability and diversity. In view of the use of GM crops and microbes in agricultural settings, in this mini-review we focus particularly on the presence and role of MGE in soil and plant-associated bacteria and the factors affecting gene transfer.

Screening and characterization of phosphate solubilizing bacteria from isolate of thermophilic bacteria

Science.gov (United States)

Yulianti, Evy; Rakhmawati, Anna

2017-08-01

The aims of this study were to select bacteria that has the ability to dissolve phosphate from thermophilic bacteria isolates after the Merapi eruption. Five isolates of selected bacteria was characterized and continued with identification. Selection was done by using a pikovskaya selective medium. Bacterial isolates were grown in selective medium and incubated for 48 hours at temperature of 55 ° C. Characterization was done by looking at the cell and colony morphology, physiological and biochemical properties. Identification was done with the Profile Matching method based on the reference genus Oscillospira traced through Bergey's Manual of Determinative Bacteriology. Dendogram was created based on similarity index SSM. The results showed there were 14 isolates of bacteria that were able to dissolve phosphate indicated by a clear zone surrounding the bacterial colony on selective media. Five isolates were selected with the largest clear zone. Isolates D79, D92, D110a, D135 and D75 have different characters. The result of phenotypic characters identification with Genus Oscillospira profile has a percentage of 100% similarity to isolate D92 and D110a; 92.31% for isolates D79, and 84.6% for isolates D75 and D135. Dendogram generated from average linkage algorithm / UPGMA using the Simple Matching Coefficient (SSM) algorithms showed, isolate thermophilic bacteria D75 and D135 are combined together to form cluster 1. D110a and D92 form a sub cluster A. Sub cluster A and D79 form cluster 2

Deployable micro-traps to sequester motile bacteria

Science.gov (United States)

di Giacomo, Raffaele; Krödel, Sebastian; Maresca, Bruno; Benzoni, Patrizia; Rusconi, Roberto; Stocker, Roman; Daraio, Chiara

2017-04-01

The development of strategies to reduce the load of unwanted bacteria is a fundamental challenge in industrial processing, environmental sciences and medical applications. Here, we report a new method to sequester motile bacteria from a liquid, based on passive, deployable micro-traps that confine bacteria using micro-funnels that open into trapping chambers. Even in low concentrations, micro-traps afford a 70% reduction in the amount of bacteria in a liquid sample, with a potential to reach >90% as shown by modelling improved geometries. This work introduces a new approach to contain the growth of bacteria without chemical means, an advantage of particular importance given the alarming growth of pan-drug-resistant bacteria.

COMPETITION BETWEEN ANOXYGENIC PHOTOTROPHIC BACTERIA AND COLORLESS SULFUR BACTERIA IN A MICROBIAL MAT

NARCIS (Netherlands)

VISSCHER, PT; VANDENENDE, FP; SCHAUB, BEM; VANGEMERDEN, H

The populations of chemolithoautotrophic (colorless) sulfur bacteria and anoxygenic phototrophic bacteria were enumerated in a marine microbial mat. The highest population densities were found in the 0-5 mm layer of the mat: 2.0 X 10(9) cells CM-3 sediment, and 4.0 X 10(7) cells cm-3 sediment for

Quorum sensing in gram-negative bacteria

DEFF Research Database (Denmark)

Wu, H.; Song, Z.J.; Høiby, N.

2004-01-01

Bacteria can communicate with each other by means of signal molecules to coordinate the behavior of the entire community, and the mechanism is referred to as quorum sensing (QS). Signal systems enable bacteria to sense the size of their densities by monitoring the concentration of the signal...... molecules. Among Gram-negative bacteria N-acyl-L-homoserine lactone (acyl-HSL)-dependent quorum sensing systems are particularly widespread. These systems are used to coordinate expression of phenotypes that are fundamental to the interaction of bacteria with each other and with their environment...

Laser-Based Identification of Pathogenic Bacteria

Science.gov (United States)

Rehse, Steven J.

2009-01-01

Bacteria are ubiquitous in our world. From our homes, to our work environment, to our own bodies, bacteria are the omnipresent although often unobserved companions to human life. Physicists are typically untroubled professionally by the presence of these bacteria, as their study usually falls safely outside the realm of our typical domain. In the…

Mimicking Seawater For Culturing Marine Bacteria

DEFF Research Database (Denmark)

Rygaard, Anita Mac; Sonnenschein, Eva; Gram, Lone

2015-01-01

Only about 1% of marine bacteria have been brought into culture using traditional techniques. The purpose of this study was to investigate if mimicking the natural bacterial environment can increase culturability.We used marine substrates containing defined algal polymers or gellan gum as solidif......Only about 1% of marine bacteria have been brought into culture using traditional techniques. The purpose of this study was to investigate if mimicking the natural bacterial environment can increase culturability.We used marine substrates containing defined algal polymers or gellan gum...... as solidifying agents, and enumerated bacteria from seawater and algal exudates. We tested if culturability could be influenced by addition of quorum sensing signals (AHLs). All plates were incubated at 15°C. Bacterial counts (CFU/g) from algal exudates from brown algae were highest on media containing algal...... polymers. In general, bacteria isolated from algal exudates preferred more rich media than bacteria isolated from seawater. Overall, culturability ranged from 0.01 to 0.8% as compared to total cell count. Substitution of agar with gellan gum increased the culturability of seawater bacteria approximately...

Antibiotic-resistant bacteria in drinking water.

Science.gov (United States)

Armstrong, J L; Shigeno, D S; Calomiris, J J; Seidler, R J

1981-08-01

We analyzed drinking water from seven communities for multiply antibiotic-resistant (MAR) bacteria (bacteria resistant to two or more antibiotics) and screened the MAR bacterial isolates obtained against five antibiotics by replica plating. Overall, 33.9% of 2,653 standard plate count bacteria from treated drinking waters were MAR. Two different raw water supplies for two communities carried MAR standard plate count bacteria at frequencies of 20.4 and 18.6%, whereas 36.7 and 67.8% of the standard plate count populations from sites within the respective distribution systems were MAR. Isolate identification revealed that MAR gram-positive cocci (Staphylococcus) and MAR gram-negative, nonfermentative rods (Pseudomonas, Alcaligenes, Moraxella-like group M, and Acinetobacter) were more common in drinking waters than in untreated source waters. Site-to-site variations in generic types and differences in the incidences of MAR organisms indicated that shedding of MAR bacteria living in pipelines may have contributed to the MAR populations in tap water. We conclude that the treatment of raw water and its subsequent distribution select for standard plate count bacteria exhibiting the MAR phenotype.

Extracellular deoxyribonuclease production by periodontal bacteria.

Science.gov (United States)

Palmer, L J; Chapple, I L C; Wright, H J; Roberts, A; Cooper, P R

2012-08-01

Whilst certain bacteria have long been known to secrete extracellular deoxyribonuclease (DNase), the purpose in microbial physiology was unclear. Recently, however, this enzyme has been demonstrated to confer enhanced virulence, enabling bacteria to evade the host's immune defence of extruded DNA/chromatin filaments, termed neutrophil extracellular traps (NETs). As NETs have recently been identified in infected periodontal tissue, the aim of this study was to screen periodontal bacteria for extracellular DNase activity. To determine whether DNase activity was membrane bound or secreted, 34 periodontal bacteria were cultured in broth and on agar plates. Pelleted bacteria and supernatants from broth cultures were analysed for their ability to degrade DNA, with relative activity levels determined using an agarose gel electrophoresis assay. Following culture on DNA-supplemented agar, expression was determined by the presence of a zone of hydrolysis and DNase activity related to colony size. Twenty-seven bacteria, including red and orange complex members Porphyromonas gingivalis, Tannerella forsythia, Fusobacterium nucleatum, Parvimonas micra, Prevotella intermedia, Streptococcus constellatus, Campylobacter rectus and Prevotella nigrescens, were observed to express extracellular DNase activity. Differences in DNase activity were noted, however, when bacteria were assayed in different culture states. Analysis of the activity of secreted DNase from bacterial broth cultures confirmed their ability to degrade NETs. The present study demonstrates, for the first time, that DNase activity is a relatively common property of bacteria associated with advanced periodontal disease. Further work is required to determine the importance of this bacterial DNase activity in the pathogenesis of periodontitis. © 2011 John Wiley & Sons A/S.

BioNLP Shared Task--The Bacteria Track.

Science.gov (United States)

Bossy, Robert; Jourde, Julien; Manine, Alain-Pierre; Veber, Philippe; Alphonse, Erick; van de Guchte, Maarten; Bessières, Philippe; Nédellec, Claire

2012-06-26

We present the BioNLP 2011 Shared Task Bacteria Track, the first Information Extraction challenge entirely dedicated to bacteria. It includes three tasks that cover different levels of biological knowledge. The Bacteria Gene Renaming supporting task is aimed at extracting gene renaming and gene name synonymy in PubMed abstracts. The Bacteria Gene Interaction is a gene/protein interaction extraction task from individual sentences. The interactions have been categorized into ten different sub-types, thus giving a detailed account of genetic regulations at the molecular level. Finally, the Bacteria Biotopes task focuses on the localization and environment of bacteria mentioned in textbook articles. We describe the process of creation for the three corpora, including document acquisition and manual annotation, as well as the metrics used to evaluate the participants' submissions. Three teams submitted to the Bacteria Gene Renaming task; the best team achieved an F-score of 87%. For the Bacteria Gene Interaction task, the only participant's score had reached a global F-score of 77%, although the system efficiency varies significantly from one sub-type to another. Three teams submitted to the Bacteria Biotopes task with very different approaches; the best team achieved an F-score of 45%. However, the detailed study of the participating systems efficiency reveals the strengths and weaknesses of each participating system. The three tasks of the Bacteria Track offer participants a chance to address a wide range of issues in Information Extraction, including entity recognition, semantic typing and coreference resolution. We found common trends in the most efficient systems: the systematic use of syntactic dependencies and machine learning. Nevertheless, the originality of the Bacteria Biotopes task encouraged the use of interesting novel methods and techniques, such as term compositionality, scopes wider than the sentence.

The Microworld of Marine-Bacteria

DEFF Research Database (Denmark)

JØRGENSEN, BB

1995-01-01

Microsensor studies show that the marine environment in the size scale of bacteria is physically and chemically very different from the macroenvironment. The microbial world of the sediment-water interface is thus dominated by water viscosity and steep diffusion gradients. Because of the diverse...... metabolism types, bacteria in the mostly anoxic sea floor play an important role in the major element cycles of the ocean. The communities of giant, filamentous sulfur bacteria that live in the deep-sea hydrothermal vents or along the Pacific coast of South America are presented here as examples....

An endoparasitic trichodinid (Ciliophora: Peritrichia) from the urinary ...

African Journals Online (AJOL)

1988-09-07

Sep 7, 1988 ... During parasitological surveys in Gazankulu, an infection of a trichodinid peritrich was found in the urinary bladder and ureters of the three-spot barb, Barbus trimaculatus Peters, 1852, collected from Hudson-. Ntsanwisi Dam in the Olifants River system. A taxonomic description of this new species, ...

Magnetotactic bacteria at the geomagnetic equator

International Nuclear Information System (INIS)

Frankel, R.B.; Blakemore, R.P.; Araujo, F.F.T. de; Esquivel, D.M.S.; Danon, J.

1981-01-01

Magnetotatic bacteria are observed in freshwater and marine sediments of Fortaleza, Brazil, situated close to the geomagnetic equator. Both South-seeking and North-seeking bacteria are present in roughly equal numbers in the same samples. This observation is consistent with the hypothesis that the vertical component of the geomagnetic field selects the predominant polarity type among magnetotactic bacteria in natural environments. (Author) [pt

Minimum Requirements of Flagellation and Motility for Infection of Agrobacterium sp. Strain H13-3 by Flagellotropic Bacteriophage 7-7-1

Science.gov (United States)

Yen, Jiun Y.; Broadway, Katherine M.

2012-01-01

The flagellotropic phage 7-7-1 specifically adsorbs to Agrobacterium sp. strain H13-3 (formerly Rhizobium lupini H13-3) flagella for efficient host infection. The Agrobacterium sp. H13-3 flagellum is complex and consists of three flagellin proteins: the primary flagellin FlaA, which is essential for motility, and the secondary flagellins FlaB and FlaD, which have minor functions in motility. Using quantitative infectivity assays, we showed that absence of FlaD had no effect on phage infection, while absence of FlaB resulted in a 2.5-fold increase in infectivity. A flaA deletion strain, which produces straight and severely truncated flagella, experienced a significantly reduced infectivity, similar to that of a flaB flaD strain, which produces a low number of straight flagella. A strain lacking all three flagellin genes is phage resistant. In addition to flagellation, flagellar rotation is required for infection. A strain that is nonmotile due to an in-frame deletion in the gene encoding the motor component MotA is resistant to phage infection. We also generated two strains with point mutations in the motA gene resulting in replacement of the conserved charged residue Glu98, which is important for modulation of rotary speed. A change to the neutral Gln caused the flagellar motor to rotate at a constant high speed, allowing a 2.2-fold-enhanced infectivity. A change to the positively charged Lys caused a jiggly motility phenotype with very slow flagellar rotation, which significantly reduced the efficiency of infection. In conclusion, flagellar number and length, as well as speed of flagellar rotation, are important determinants for infection by phage 7-7-1. PMID:22865074

The Effect of Bacteria Penetration on Chalk Permeability

DEFF Research Database (Denmark)

Halim, Amalia Yunita; Shapiro, Alexander; Nielsen, Sidsel Marie

number of B. licheniformis was detected on the effluent compared with P. putida. However, in the experiment with B. licheniformis mainly spores were detected in the effluent. The core permeability decreased rapidly during injection of bacteria and a starvation period of 12 days did not allow......Bacteria selective plugging is one of the mechanisms through which microorganisms can be applied for enhanced oil recovery. Bacteria can plug the water-bearing zones of a reservoir, thus altering the flow paths and improving sweep efficiency. It is known that the bacteria can penetrate deeply...... into reservoirs, however, a complete understanding of the penetration behavior of bacteria is lacking, especially in chalk formations where the pore throat sizes are almost comparable with the sizes of bacteria vegetative cells. This study investigates the penetration of bacteria into chalk. Two bacteria types...

Bioenergetics of photoheterotrophic bacteria in the oceans.

Science.gov (United States)

Kirchman, David L; Hanson, Thomas E

2013-04-01

Photoheterotrophic microbes, such as proteorhodopsin (PR)-based phototrophic (PRP) and aerobic anoxygenic phototrophic (AAP) bacteria, are well known to be abundant in the oceans, potentially playing unique roles in biogeochemical cycles. However, the contribution of phototrophy to the energy requirements of these bacteria has not been quantitatively examined to date. To better understand the implications of photoheterophy in the oceans, we calculated energy benefits and costs of phototrophy and compared net benefits with maintenance costs. Benefits depend on the number of photosynthetic units (PSUs), absorption cross-section area of each PSU as function of wavelength, the in situ light quality, and the energy yield per absorbed photon. For costs we considered the energy required for the synthesis of pigments, amino acids and proteins in each PSU. Our calculations indicate that AAP bacteria harvest more light energy than do PRP bacteria, but the costs of phototrophy are much higher for AAP bacteria. Still, the net energy gained by AAP bacteria is often sufficient to meet maintenance costs, while that is not the case for PRP bacteria except with high light intensities and large numbers of proteorhodopsin molecules per cell. The low costs and simplicity of PR-based phototrophy explain the high abundance of proteorhodopsin genes in the oceans. However, even for AAP bacteria, the net energy yield of phototrophy is apparently too low to influence the distribution of photoheterotrophic bacteria among various marine systems. © 2012 Society for Applied Microbiology and Blackwell Publishing Ltd.

Ecophysiology of the Anammox Bacteria

NARCIS (Netherlands)

Kartal, M.B.

2008-01-01

Anaerobic ammonium oxidizing (anammox) bacteria oxidize ammonium to dinitrogen gas with nitrite as the electron acceptor. These bacteria are the key players in the global nitrogen cycle, responsible for the most of nitrogen production in natural ecosystems. The anammox process is also a

Electron transport chains of lactic acid bacteria

NARCIS (Netherlands)

Brooijmans, R.J.W.

2008-01-01

Lactic acid bacteria are generally considered facultative anaerobic obligate fermentative bacteria. They are unable to synthesize heme. Some lactic acid bacteria are unable to form menaquinone as well. Both these components are cofactors of respiratory (electron transport) chains of prokaryotic

Antibacterial Activities of Endophytic Bacteria Isolated from Taxus brevifolia Against Foodborne Pathogenic Bacteria.

Science.gov (United States)

Islam, Nurul; Choi, Jaehyuk; Baek, Kwang-Hyun

2018-05-01

Endophytes are a potential source of novel bioactive compounds with medicinal properties. In this study, 41 endophytic bacteria (EB) were isolated from tissues of a medicinally important plant Taxus brevifolia (Pacific yew). The objective was to screen all the EB isolates for their antibacterial effects against five foodborne pathogenic bacteria: Bacillus cereus ATCC10876, Staphylococcus aureus ATCC12600, Listeria monocytogenes ATCC19115, Escherichia coli ATCC43890, and Salmonella Typhimurium ATCC19585. Among the EB isolates, T. brevifolia seed (TbS)-8, T. brevifolia fleshy part of fruit (TbFl)-10, T. brevifolia leaf (TbL)-22, TbS-29, and TbL-34 exerted significant antibacterial activity against the tested foodborne pathogens. Especially TbFl-10 showed the highest antibacterial activity against all the tested bacteria and was identified as Paenibacillus kribbensis (Pk). Furthermore, an ethyl acetate extract of Pk-TbFl-10 possessed antibacterial activities against the tested five foodborne pathogenic bacteria, with zones of inhibition from 15.71 ± 2.85 to 13.01 ± 2.12 mm. Scanning electron microscopy analysis revealed ruptured, lysed, shrunk, and swollen cells of all the tested foodborne pathogens treated with the ethyl acetate extract of Pk-TbFl-10, suggesting that a metabolite(s) of Pk-TbFl-10 penetrates the cell membrane and causes cell lysis leading to cell death. Our results indicate that Pk-TbFl-10 isolated from T. brevifolia can serve as a novel source of natural antibacterial agents against foodborne pathogenic bacteria, with potential applications in the pharmaceutical industry.

Money and transmission of bacteria.

NARCIS (Netherlands)

Gedik, H.; Voss, T.A.; Voss, A.

2013-01-01

Money is one of the most frequently passed items in the world. The aim of this study was to ascertain the survival status of bacteria including Staphylococcus aureus, Escherichia coli, and Vancomycin- Resistant Enterococci (VRE) on banknotes from different countries and the transmission of bacteria

Review on SERS of Bacteria

Directory of Open Access Journals (Sweden)

Pamela A. Mosier-Boss

2017-11-01

Full Text Available Surface enhanced Raman spectroscopy (SERS has been widely used for chemical detection. Moreover, the inherent richness of the spectral data has made SERS attractive for use in detecting biological materials, including bacteria. This review discusses methods that have been used to obtain SERS spectra of bacteria. The kinds of SERS substrates employed to obtain SERS spectra are discussed as well as how bacteria interact with silver and gold nanoparticles. The roll of capping agents on Ag/Au NPs in obtaining SERS spectra is examined as well as the interpretation of the spectral data.

Using Fluorescent Viruses for Detecting Bacteria in Water

Science.gov (United States)

Tabacco, Mary Beth; Qian, Xiaohua; Russo, Jaimie A.

2009-01-01

A method of detecting water-borne pathogenic bacteria is based partly on established molecular-recognition and fluorescent-labeling concepts, according to which bacteria of a species of interest are labeled with fluorescent reporter molecules and the bacteria can then be detected by fluorescence spectroscopy. The novelty of the present method lies in the use of bacteriophages (viruses that infect bacteria) to deliver the fluorescent reporter molecules to the bacteria of the species of interest.

Screening and biological characteristics of fufenozide degrading bacteria

Science.gov (United States)

Xu, Chenhao; Gong, Mingfu; Guan, Qinlan; Deng, Xia; Deng, Hongyan; Huang, Jiao

2018-04-01

Fufenozide was a novel pesticide for the control of Lepidoptera pests, which was highly toxic to silkworm. Fufenozide-contaminated soil samples were collected and the bacteria that degrade fufenozide were isolated and screened by selective medium. The colony characteristics, cell characteristics and degradation characteristics in different concentrations fufenozide of the fufenozide degrading bacteria were studied. The results indicated that seven strains of fufenozide degradeing bacteria, named as DDH01, DDH03, DDH04, DDH04, DDH05, DDH07 and DDH07 respectively, were isolated from soil contaminated with fufenozide. DDH01, DDH02, DDH04 and DDH05 of seven fufenozide degrading bacteria, was gram-positive bacteria, and DDH03, DDH06 and DDH07 was gram-negative bacteria. All of seven strains of fufenozide degrading bacteria were not spores, weeks flagella, rod-shaped bacteria. DDH06 and DDH07 had capsules, and the remaining five strains had not capsule. The colonies formed by seven strains of fufenozide degradation bacteria on beef extract peptone medium plate were milky white colonies with irregular edges, thinner lawn, smaller colony with smooth surface. The growth of 7 strains of fufenozide degradation bacteria was significantly affected by the concentration of fufenozide, All of 7 strains grown in the range from 0.00025 g/mL to 1 g/mL of 10% fufenozide suspension. DDH2 was the best among the 7 strains of fufenozide degrading bacteria grown in 10% fufenozide suspension medium.

HYDROCARBON-DEGRADING BACTERIA AND SURFACTANT ACTIVITY

Energy Technology Data Exchange (ETDEWEB)

Brigmon, R; Topher Berry, T; Grazyna A. Plaza, G; jacek Wypych, j

2006-08-15

Fate of benzene ethylbenzene toluene xylenes (BTEX) compounds through biodegradation was investigated using two different bacteria, Ralstonia picketti (BP-20) and Alcaligenes piechaudii (CZOR L-1B). These bacteria were isolated from extremely polluted petroleum hydrocarbon contaminated soils. PCR and Fatty Acid Methyl Ester (FAME) were used to identify the isolates. Biodegradation was measured using each organism individually and in combination. Both bacteria were shown to degrade each of the BTEX compounds. Alcaligenes piechaudii biodegraded BTEXs more efficiently while mixed with BP-20 and individually. Biosurfactant production was observed by culture techniques. In addition 3-hydroxy fatty acids, important in biosurfactant production, was observed by FAME analysis. In the all experiments toluene and m+p- xylenes were better growth substrates for both bacteria than the other BTEX compounds. In addition, the test results indicate that the bacteria could contribute to bioremediation of aromatic hydrocarbons (BTEX) pollution increase biodegradation through the action by biosurfactants.

Acetic acid bacteria: A group of bacteria with versatile biotechnological applications.

Science.gov (United States)

Saichana, Natsaran; Matsushita, Kazunobu; Adachi, Osao; Frébort, Ivo; Frebortova, Jitka

2015-11-01

Acetic acid bacteria are gram-negative obligate aerobic bacteria assigned to the family Acetobacteraceae of Alphaproteobacteria. They are members of the genera Acetobacter, Gluconobacter, Gluconacetobacter, Acidomonas, Asaia, Kozakia, Swaminathania, Saccharibacter, Neoasaia, Granulibacter, Tanticharoenia, Ameyamaea, Neokomagataea, and Komagataeibacter. Many strains of Acetobacter and Komagataeibacter have been known to possess high acetic acid fermentation ability as well as the acetic acid and ethanol resistance, which are considered to be useful features for industrial production of acetic acid and vinegar, the commercial product. On the other hand, Gluconobacter strains have the ability to perform oxidative fermentation of various sugars, sugar alcohols, and sugar acids leading to the formation of several valuable products. Thermotolerant strains of acetic acid bacteria were isolated in order to serve as the new strains of choice for industrial fermentations, in which the cooling costs for maintaining optimum growth and production temperature in the fermentation vessels could be significantly reduced. Genetic modifications by adaptation and genetic engineering were also applied to improve their properties, such as productivity and heat resistance. Copyright © 2014 Elsevier Inc. All rights reserved.

Bacteria-mediated bisphenol A degradation.

Science.gov (United States)

Zhang, Weiwei; Yin, Kun; Chen, Lingxin

2013-07-01

Bisphenol A (BPA) is an important monomer in the manufacture of polycarbonate plastics, food cans, and other daily used chemicals. Daily and worldwide usage of BPA and BPA-contained products led to its ubiquitous distribution in water, sediment/soil, and atmosphere. Moreover, BPA has been identified as an environmental endocrine disruptor for its estrogenic and genotoxic activity. Thus, BPA contamination in the environment is an increasingly worldwide concern, and methods to efficiently remove BPA from the environment are urgently recommended. Although many factors affect the fate of BPA in the environment, BPA degradation is mainly depended on the metabolism of bacteria. Many BPA-degrading bacteria have been identified from water, sediment/soil, and wastewater treatment plants. Metabolic pathways of BPA degradation in specific bacterial strains were proposed, based on the metabolic intermediates detected during the degradation process. In this review, the BPA-degrading bacteria were summarized, and the (proposed) BPA degradation pathway mediated by bacteria were referred.

Bacteria in atmospheric waters: Detection, characteristics and implications

Science.gov (United States)

Hu, Wei; Niu, Hongya; Murata, Kotaro; Wu, Zhijun; Hu, Min; Kojima, Tomoko; Zhang, Daizhou

2018-04-01

In this review paper, we synthesize the current knowledges about bacteria in atmospheric waters, e.g., cloud, fog, rain, and snow, most of which were obtained very recently. First, we briefly describe the importance of bacteria in atmospheric waters, i.e., the essentiality of studying bacteria in atmospheric waters in understanding aerosol-cloud-precipitation-climate interactions in the Earth system. Next, approaches to collect atmospheric water samples for the detection of bacteria and methods to identify the bacteria are summarized and compared. Then the available data on the abundance, viability and community composition of bacteria in atmospheric waters are summarized. The average bacterial concentration in cloud water was usually on the order 104-105 cells mL-1, while that in precipitation on the order 103-104 cells mL-1. Most of the bacteria were viable or metabolically active. Their community composition was highly diverse and differed at various sites. Factors potentially influencing the bacteria, e.g., air pollution levels and sources, meteorological conditions, seasonal effect, and physicochemical properties of atmospheric waters, are described. After that, the implications of bacteria present in atmospheric waters, including their effect on nucleation in clouds, atmospheric chemistry, ecosystems and public health, are briefly discussed. Finally, based on the current knowledges on bacteria in atmospheric waters, which in fact remains largely unknown, we give perspectives that should be paid attention to in future studies.

Enrichment of specific protozoan populations during in situ bioremediation of uranium-contaminated groundwater

Energy Technology Data Exchange (ETDEWEB)

Holmes, Dawn; Giloteaux, L.; Williams, Kenneth H.; Wrighton, Kelly C.; Wilkins, Michael J.; Thompson, Courtney A.; Roper, Thomas J.; Long, Philip E.; Lovley, Derek

2013-07-28

The importance of bacteria in the anaerobic bioremediation of groundwater polluted with organic and/or metal contaminants is well-recognized and in some instances so well understood that modeling of the in situ metabolic activity of the relevant subsurface microorganisms in response to changes in subsurface geochemistry is feasible. However, a potentially significant factor influencing bacterial growth and activity in the subsurface that has not been adequately addressed is protozoan predation of the microorganisms responsible for bioremediation. In field experiments at a uranium-contaminated aquifer located in Rifle, CO, acetate amendments initially promoted the growth of metal-reducing Geobacter species followed by the growth of sulfate-reducers, as previously observed. Analysis of 18S rRNA gene sequences revealed a broad diversity of sequences closely related to known bacteriovorous protozoa in the groundwater prior to the addition of acetate. The bloom of Geobacter species was accompanied by a specific enrichment of sequences most closely related to the amoeboid flagellate, Breviata anathema, which at their peak accounted for over 80% of the sequences recovered. The abundance of Geobacter species declined following the rapid emergence of B. anathema. The subsequent growth of sulfate-reducing Peptococcaceae was accompanied by another specific enrichment of protozoa, but with sequences most similar to diplomonadid flagellates from the family Hexamitidae, which accounted for up to 100% of the sequences recovered during this phase of the bioremediation. These results suggest a prey-predator response with specific protozoa responding to increased availability of preferred prey bacteria. Thus, quantifying the influence of protozoan predation on the growth, activity, and composition of the subsurface bacterial community is essential for predictive modeling of in situ uranium bioremediation strategies.

Magnetic Bacteria.

Science.gov (United States)

Nelson, Jane Bray; Nelson, Jim

1992-01-01

Describes the history of Richard Blakemore's discovery of magnetotaxic organisms. Discusses possible reasons why the magnetic response in bacteria developed. Proposes research experiments integrating biology and physics in which students investigate problems using cultures of magnetotaxic organisms. (MDH)

Ecology of mycophagous collimonas bacteria in soil

NARCIS (Netherlands)

Höppener-Ogawa, Sachie

2008-01-01

Bacteria belonging to the genus Collimonas consist of soil bacteria that can grow at expense of living fungal hyphae i.e. they are mycophagous. This PhD studies deals with the ecology of mycophagous bacteria in soil using collimonads as model organisms. Collimonads were found to be widely

Fourier transform-infrared spectroscopic methods for microbial ecology: analysis of bacteria, bacteria-polymer mixtures and biofilms

Science.gov (United States)

Nichols, P. D.; Henson, J. M.; Guckert, J. B.; Nivens, D. E.; White, D. C.

1985-01-01

Fourier transform-infrared (FT-IR) spectroscopy has been used to rapidly and nondestructively analyze bacteria, bacteria-polymer mixtures, digester samples and microbial biofilms. Diffuse reflectance FT-IR (DRIFT) analysis of freeze-dried, powdered samples offered a means of obtaining structural information. The bacteria examined were divided into two groups. The first group was characterized by a dominant amide I band and the second group of organisms displayed an additional strong carbonyl stretch at approximately 1740 cm-1. The differences illustrated by the subtraction spectra obtained for microbes of the two groups suggest that FT-IR spectroscopy can be utilized to recognize differences in microbial community structure. Calculation of specific band ratios has enabled the composition of bacteria and extracellular or intracellular storage product polymer mixtures to be determined for bacteria-gum arabic (amide I/carbohydrate C-O approximately 1150 cm-1) and bacteria-poly-beta-hydroxybutyrate (amide I/carbonyl approximately 1740 cm-1). The key band ratios correlate with the compositions of the material and provide useful information for the application of FT-IR spectroscopy to environmental biofilm samples and for distinguishing bacteria grown under differing nutrient conditions. DRIFT spectra have been obtained for biofilms produced by Vibrio natriegens on stainless steel disks. Between 48 and 144 h, an increase in bands at approximately 1440 and 1090 cm-1 was seen in FT-IR spectra of the V. natriegens biofilm. DRIFT spectra of mixed culture effluents of anaerobic digesters show differences induced by shifts in input feedstocks. The use of flow-through attenuated total reflectance has permitted in situ real-time changes in biofilm formation to be monitored and provides a powerful tool for understanding the interactions within adherent microbial consortia.

Emerging role of bacteria in oral carcinogenesis: a review with special reference to perio-pathogenic bacteria.

Science.gov (United States)

Perera, Manosha; Al-Hebshi, Nezar Noor; Speicher, David J; Perera, Irosha; Johnson, Newell W

2016-01-01

Oral cancer, primarily oral squamous cell carcinoma (OSCC), continues to be a major global health problem with high incidence and low survival rates. While the major risk factors for this malignancy, mostly lifestyle related, have been identified, around 15% of oral cancer cases remain unexplained. In light of evidence implicating bacteria in the aetiology of some cancer types, several epidemiological studies have been conducted in the last decade, employing methodologies ranging from traditional culture techniques to 16S rRNA metagenomics, to assess the possible role of bacteria in OSCC. While these studies have demonstrated differences in microbial composition between cancerous and healthy tissues, they have failed to agree on specific bacteria or patterns of oral microbial dysbiosis to implicate in OSCC. On the contrary, some oral taxa, particularly Porphyromonas gingivalis and Fusobacterium nucleatum, show strong oral carcinogenic potential in vitro and in animal studies. Bacteria are thought to contribute to oral carcinogenesis via inhibition of apoptosis, activation of cell proliferation, promotion of cellular invasion, induction of chronic inflammation, and production of carcinogens. This narrative review provides a critical analysis of and an update on the association between bacteria and oral carcinogenesis and the possible mechanisms underlying it.

New thermophilic anaerobes that decompose crystalline cellulose

Energy Technology Data Exchange (ETDEWEB)

Taya, M; Hinoki, H; Suzuki, Y; Yagi, T; Yap, M G.S.; Kobayashi, T

1985-01-01

Two strains (designated as 25A and 3B) of cellulolytic, thermophilic, anaerobic, spore-forming bacteria were newly isolated from an alkaline hot spring through enrichment cultures at 60/sup 0/C. Though strain 25A was nearly identical to Clostridium thermocellum ATCC 27405 as a reference strain, strain 3B had some characteristics different from the reference; no flagellation, alkalophilic growth property (optimum pH of 7.5-8) and orange-colored pigmentation of the cell mass. Strain 3B effectively decomposed micro-crystalline cellulose (Avicel) and raw cellulosics (rice straw, newspaper, and bagasse) without physical or chemical pretreatments. 20 references, 2 figures, 2 tables.

Lipopolysaccharides in diazotrophic bacteria

OpenAIRE

Serrato, Rodrigo V.

2014-01-01

Biological nitrogen fixation (BNF) is a process in which the atmospheric nitrogen (N2) is transformed into ammonia (NH3) by a select group of nitrogen-fixing organisms, or diazotrophic bacteria. In order to furnish the biologically useful nitrogen to plants, these bacteria must be in constant molecular communication with their host plants. Some of these molecular plant-microbe interactions are very specific, resulting in a symbiotic relationship between the diazotroph and the host. Others are...

Coryneform bacteria associated with canine otitis externa

DEFF Research Database (Denmark)

Aalbæk, Bent; Bemis, David A.; Schjærff, Mette

2010-01-01

This study aims to investigate the occurrence of coryneform bacteria in canine otitis externa. A combined case series and case-control study was carried out to improve the current knowledge on frequency and clinical significance of coryneform bacteria in samples from canine otitis externa. A total...... of 16 cases of otitis externa with involvement of coryneform bacteria were recorded at two referral veterinary hospitals in Denmark and the US, respectively. Coryneform bacteria were identified by partial 16S rRNA gene sequencing. Corynebacterium auriscanis was the most common coryneform species (10...... cases). Small colony variants of this species were also observed. Other coryneform isolates were identified as Corynebacterium amycolatum (3 cases), Corynebacterium freneyi (2 cases) and an Arcanobacterium-like species (1 case). The coryneform bacteria were in all cases isolated together with other...

Bacteria classification using Cyranose 320 electronic nose

Directory of Open Access Journals (Sweden)

Gardner Julian W

2002-10-01

Full Text Available Abstract Background An electronic nose (e-nose, the Cyrano Sciences' Cyranose 320, comprising an array of thirty-two polymer carbon black composite sensors has been used to identify six species of bacteria responsible for eye infections when present at a range of concentrations in saline solutions. Readings were taken from the headspace of the samples by manually introducing the portable e-nose system into a sterile glass containing a fixed volume of bacteria in suspension. Gathered data were a very complex mixture of different chemical compounds. Method Linear Principal Component Analysis (PCA method was able to classify four classes of bacteria out of six classes though in reality other two classes were not better evident from PCA analysis and we got 74% classification accuracy from PCA. An innovative data clustering approach was investigated for these bacteria data by combining the 3-dimensional scatter plot, Fuzzy C Means (FCM and Self Organizing Map (SOM network. Using these three data clustering algorithms simultaneously better 'classification' of six eye bacteria classes were represented. Then three supervised classifiers, namely Multi Layer Perceptron (MLP, Probabilistic Neural network (PNN and Radial basis function network (RBF, were used to classify the six bacteria classes. Results A [6 × 1] SOM network gave 96% accuracy for bacteria classification which was best accuracy. A comparative evaluation of the classifiers was conducted for this application. The best results suggest that we are able to predict six classes of bacteria with up to 98% accuracy with the application of the RBF network. Conclusion This type of bacteria data analysis and feature extraction is very difficult. But we can conclude that this combined use of three nonlinear methods can solve the feature extraction problem with very complex data and enhance the performance of Cyranose 320.

Communication among Oral Bacteria

Science.gov (United States)

Kolenbrander, Paul E.; Andersen, Roxanna N.; Blehert, David S.; Egland, Paul G.; Foster, Jamie S.; Palmer, Robert J.

2002-01-01

Human oral bacteria interact with their environment by attaching to surfaces and establishing mixed-species communities. As each bacterial cell attaches, it forms a new surface to which other cells can adhere. Adherence and community development are spatiotemporal; such order requires communication. The discovery of soluble signals, such as autoinducer-2, that may be exchanged within multispecies communities to convey information between organisms has emerged as a new research direction. Direct-contact signals, such as adhesins and receptors, that elicit changes in gene expression after cell-cell contact and biofilm growth are also an active research area. Considering that the majority of oral bacteria are organized in dense three-dimensional biofilms on teeth, confocal microscopy and fluorescently labeled probes provide valuable approaches for investigating the architecture of these organized communities in situ. Oral biofilms are readily accessible to microbiologists and are excellent model systems for studies of microbial communication. One attractive model system is a saliva-coated flowcell with oral bacterial biofilms growing on saliva as the sole nutrient source; an intergeneric mutualism is discussed. Several oral bacterial species are amenable to genetic manipulation for molecular characterization of communication both among bacteria and between bacteria and the host. A successful search for genes critical for mixed-species community organization will be accomplished only when it is conducted with mixed-species communities. PMID:12209001

Automated radiometric detection of bacteria

International Nuclear Information System (INIS)

Waters, J.R.

1974-01-01

A new radiometric method called BACTEC, used for the detection of bacteria in cultures or in supposedly sterile samples, was discussed from the standpoint of methodology, both automated and semi-automated. Some of the results obtained so far were reported and some future applications and development possibilities were described. In this new method, the test sample is incubated in a sealed vial with a liquid culture medium containing a 14 C-labeled substrate. If bacteria are present, they break down the substrate, producing 14 CO 2 which is periodically extracted from the vial as a gas and is tested for radioactivity. If this gaseous radioactivity exceeds a threshold level, it is evidence of bacterial presence and growth in the test vial. The first application was for the detection of bacteria in the blood cultures of hospital patients. Data were presented showing typical results. Also discussed were future applications, such as rapid screening for bacteria in urine industrial sterility testing and the disposal of used 14 C substrates. (Mukohata, S.)

Interactions among sulfide-oxidizing bacteria

Science.gov (United States)

Poplawski, R.

1985-01-01

The responses of different phototrophic bacteria in a competitive experimental system are studied, one in which primary factors such as H2S or light limited photometabolism. Two different types of bacteria shared one limited source of sulfide under specific conditions of light. The selection of a purple and a green sulfur bacteria and the cyanobacterium was based on their physiological similarity and also on the fact that they occur together in microbial mats. They all share anoxygenic photosynthesis, and are thus probably part of an evolutionary continuum of phototrophic organisms that runs from, strictly anaerobic physiology to the ability of some cyanobacteria to shift between anoxygenic bacterial style photosynthesis and the oxygenic kind typical of eukaryotes.

Reactivity of the Bacteria-Water Interface: Linking Nutrient Availability to Bacteria-Metal Interactions

Science.gov (United States)

Fowle, D. A.; Daughney, C. J.; Riley, J. L.

2002-12-01

Identifying and quantifying the controls on metal mobilities in geologic systems is critical in order to understand processes such as global element cycling, metal transport in near-surface water-rock systems, sedimentary diagenesis, and mineral formation. Bacteria are ubiquitous in near-surface water-rock systems, and numerous laboratory and field studies have demonstrated that bacteria can facilitate the formation and dissolution of minerals, and enhance or inhibit contaminant transport. However, despite the growing evidence that bacteria play a key role in many geologic processes in low temperature systems, our understanding of the influence of the local nutrient dynamics of the system of interest on bacteria-metal interactions is limited. Here we present data demonstrating the effectiveness of coupling laboratory experiments with geochemical modeling to isolate the effect of nutrient availability on bacterially mediated proton and metal adsorption reactions. Experimental studies of metal-bacteria interactions were conducted in batch reactors as a function of pH, and solid-solute interactions after growth in a variety of defined and undefined media. Media nutrient composition (C,N,P) was quantified before and after harvesting the cells. Surface complexation models (SCM) for the adsorption reactions were developed by combining sorption data with the results of acid-base titrations, and in some cases zeta potential titrations of the bacterial surface. Our results indicate a clear change in both buffering potential and metal binding capacity of the cell walls of Bacillus subtilis as a function of initial media conditions. Combining current studies with our past studies on the effects of growth phase and others work on temperature dependence on metal adsorption we hope to develop a holistic surface complexation model for quantifying bacterial effects on metal mass transfer in many geologic systems.

Persistent Flagellate Hyperpigmentation

Science.gov (United States)

2017-04-28

medical research or technical information as a publication/presentation, a new 59 MOW Form 3039 must be submitted for review and approval.) IA 6...directives.) D DISAPPROVED 40. PRINTED NAME. RANK/GRADE, TITLE OF REVIEWER 41 . REVIEWER SIGNATURE 42 . DATE Kevin linuma, SSgt/E-5, 59 MDW Public

Influence of irradiation of bacteria on their thermoresistance

International Nuclear Information System (INIS)

Szulc, M.; Stefaniakowa, A.; Tropilo, J.; Stanczak, B.; Peconek, J.; Mierzewska, H.; Bielecka, J.

1979-01-01

The influence of x-radiation on thermoresistance of bacteria was determined. The studies were carried out on: E. coli, Pr. vulgaris, S. typhimurium, Staph. aureus and Str. faecalis. The bacteria were irradiated in PBS (physiological buffer solution) and in broth (containing about 1% of protein) with x-rays at radium absorbed doses of 100, 1000, 5000 and 10 000, which was followed immediately by heating at temperatures causing death of part of the bacteria. The results obtained indicate that irradiation of bacteria with small x-ray doses distinctly decreases their thermoresistance. Synergetic action of irradiation and heating of bacteria was observed, increasing with increased irradiation dose. The greatest changes of thermoresistance occurred with Pr. vulgaris, the smallest with S. typhimurium. Thermoresistance of bacteria decreased more strongly on their irradiation in protein-free medium (PBS). (author)

Hyphae colonizing bacteria associated with Penicillium bilaii

DEFF Research Database (Denmark)

Ghodsalavi, Behnoushsadat

shown that mycorrhizal helper bacteria presenting in mycorrhizal fungi could stimulate fungal growth, promote establishment of root-fungus symbiosis and enhance plant production. But it is unknown if the comparable relationship exist between the non-mycorrhizal fungus P. bilaii and its hyphae associated...... bacteria. In the current PhD thesis, we assumed that hyphae-associated microbiome of P. bilaii might harbor helper bacteria with ability to improve fungal growth and P solubilization performance. Therefore, we aimed to isolate bacteria associated with the P. bilaii hyphae and identify the fungal growth...... stimulating bacteria with the perspective of promoting efficiency of Jumpstart in soil – plant system. For this purpose, most of the work within the current project was carried out by development of suitable model systems by mimicking the natural soil habitat to reach to the reliable performance in soil...

Bacteria Culture Test: MedlinePlus Lab Test Information

Science.gov (United States)

... this page: https://medlineplus.gov/labtests/bacteriaculturetest.html Bacteria Culture Test To use the sharing features on this page, please enable JavaScript. What is a Bacteria Culture Test? Bacteria are a large group of ...

Chemically enhanced sunlight for killing bacteria

International Nuclear Information System (INIS)

Block, S.S.; Goswami, D.Y.

1995-01-01

Solar ultraviolet (UV) photocatalyzed oxidation of chemicals with titanium dioxide (TiO 2 ) has received considerable attention. Much less recognized, however, is the ability of the same system to destroy bacteria. This study examined this phenomenon and the conditions that affect it. Bacteria in aqueous solution were given solar exposure with titanium dioxide and their survival with time was determined. Lamps with a predominantly solar ultraviolet spectrum were also used in the experiments. Without exposure to UV light, TiO 2 had no deleterious effect on the bacteria. However, several common bacteria on solar exposure in the presence of TiO 2 were killed in just a few minutes, whereas without TiO 2 it took over an hour to destroy them. A concentration of 0.01% TiO 2 was most effective in killing bacteria and 10-fold concentrations lower or higher were successively less effective. Inorganic and organic compounds in solution, even in small amounts, interfered with the efficiency of killing. Alkaline solution also reduced the bactericidal activity. Circulation and agitation provided by stirring to keep the TiO 2 particles suspended reduced the time necessary to kill the bacteria. Time-intensity curves for killing bacteria were the same general shape with or without TiO 2 , indicating that TiO 2 served merely as a catalyst to increase the rate of the reaction but that the mechanism of action was not changed. The shape of the curves show that the organisms are sensitized with a minimum intensity of radiation and that an increase doesn't greatly increase the rate of kill. Below this critical intensity, however, the time required for killing markedly increases as the intensity is decreased

Molecular analysis of deep subsurface bacteria

International Nuclear Information System (INIS)

Jimenez Baez, L.E.

1989-09-01

Deep sediments samples from site C10a, in Appleton, and sites, P24, P28, and P29, at the Savannah River Site (SRS), near Aiken, South Carolina were studied to determine their microbial community composition, DNA homology and mol %G+C. Different geological formations with great variability in hydrogeological parameters were found across the depth profile. Phenotypic identification of deep subsurface bacteria underestimated the bacterial diversity at the three SRS sites, since bacteria with the same phenotype have different DNA composition and less than 70% DNA homology. Total DNA hybridization and mol %G+C analysis of deep sediment bacterial isolates suggested that each formation is comprised of different microbial communities. Depositional environment was more important than site and geological formation on the DNA relatedness between deep subsurface bacteria, since more 70% of bacteria with 20% or more of DNA homology came from the same depositional environments. Based on phenotypic and genotypic tests Pseudomonas spp. and Acinetobacter spp.-like bacteria were identified in 85 million years old sediments. This suggests that these microbial communities might have been adapted during a long period of time to the environmental conditions of the deep subsurface

Overlapping riboflavin supply pathways in bacteria.

Science.gov (United States)

García-Angulo, Víctor Antonio

2017-03-01

Riboflavin derivatives are essential cofactors for a myriad of flavoproteins. In bacteria, flavins importance extends beyond their role as intracellular protein cofactors, as secreted flavins are a key metabolite in a variety of physiological processes. Bacteria obtain riboflavin through the endogenous riboflavin biosynthetic pathway (RBP) or by the use of importer proteins. Bacteria frequently encode multiple paralogs of the RBP enzymes and as for other micronutrient supply pathways, biosynthesis and uptake functions largely coexist. It is proposed that bacteria shut down biosynthesis and would rather uptake riboflavin when the vitamin is environmentally available. Recently, the overlap of riboflavin provisioning elements has gained attention and the functions of duplicated paralogs of RBP enzymes started to be addressed. Results point towards the existence of a modular structure in the bacterial riboflavin supply pathways. Such structure uses subsets of RBP genes to supply riboflavin for specific functions. Given the importance of riboflavin in intra and extracellular bacterial physiology, this complex array of riboflavin provision pathways may have developed to contend with the various riboflavin requirements. In riboflavin-prototrophic bacteria, riboflavin transporters could represent a module for riboflavin provision for particular, yet unidentified processes, rather than substituting for the RBP as usually assumed.

Effect of leukocyte hydrolases on bacteria

International Nuclear Information System (INIS)

Cohen, D.; Michel, J.; Ferne, M.; Bergner-Rabinowitz, S.; Ginsburg, I.

1979-01-01

Leukocyte extracts, trypsin, and lysozyme are all capable of releasing the bulk of the LPS from S. typhi, S. typhimurium, and E. coli. Bacteria which have been killed by heat, ultraviolet irradiation, or by a variety of metabolic inhibitors and antibiotics which affect protein, DNA, RNA, and cell wall synthesis no longer yield soluble LPS following treatment with the releasing agents. On the other hand, bacteria which are resistant to certain of the antibiotics yield nearly the full amount of soluble LPS following treatment, suggesting that certain heatabile endogenous metabolic pathways collaborate with the releasing agents in the release of LPS from the bacteria. It is suggested that some of the beneficial effects of antibiotics on infections with gram-negative bacteria may be the prevention of massive release of endotoxin by leukocyte enzymes in inflammatory sites

Bacteria abundance and diversity of different life stages of Plutella xylostella (Lepidoptera: Plutellidae), revealed by bacteria culture-dependent and PCR-DGGE methods.

Science.gov (United States)

Lin, Xiao-Li; Pan, Qin-Jian; Tian, Hong-Gang; Douglas, Angela E; Liu, Tong-Xian

2015-03-01

Microbial abundance and diversity of different life stages (fourth instar larvae, pupae and adults) of the diamondback moth, Plutella xylostella L., collected from field and reared in laboratory, were investigated using bacteria culture-dependent method and PCR-DGGE analysis based on the sequence of bacteria 16S rRNA V3 region gene. A large quantity of bacteria was found in all life stages of P. xylostella. Field population had higher quantity of bacteria than laboratory population, and larval gut had higher quantity than pupae and adults. Culturable bacteria differed in different life stages of P. xylostella. Twenty-five different bacterial strains were identified in total, among them 20 strains were presented in larval gut, only 8 strains in pupae and 14 strains in adults were detected. Firmicutes bacteria, Bacillus sp., were the most dominant species in every life stage. 15 distinct bands were obtained from DGGE electrophoresis gel. The sequences blasted in GenBank database showed these bacteria belonged to six different genera. Phylogenetic analysis showed the sequences of the bacteria belonged to the Actinobacteri, Proteobacteria and Firmicutes. Serratia sp. in Proteobacteria was the most abundant species in larval gut. In pupae, unculturable bacteria were the most dominant species, and unculturable bacteria and Serratia sp. were the most dominant species in adults. Our study suggested that a combination of molecular and traditional culturing methods can be effectively used to analyze and to determine the diversity of gut microflora. These known bacteria may play important roles in development of P. xylostella. © 2013 Institute of Zoology, Chinese Academy of Sciences.

Labelling of bacteria with indium chelates

International Nuclear Information System (INIS)

Kleinert, P.; Pfister, W.; Endert, G.; Sproessig, M.

1985-01-01

The indium chelates were prepared by reaction of radioactive indiumchloride with 10 μg oxine, 15 μg tropolone and 3 mg acetylacetone, resp. The formed chelates have been incubated with 10 9 germs/ml for 5 minutes, with labelling outputs from 90 to 95%. Both gram-positive (Streptococcus, Staphylococcus) and gram-negative bacteria (Escherichia coli) can be labelled. The reproductive capacity of the bacteria was not impaired. The application of indium labelled bacteria allows to show the distribution of microorganisms within the living organism and to investigate problems of bacterial adherence. (author)

New Insights on the Ecology of Free-living, Heterotrophic Nanoflagellates Based on the Use of Molecular Biological Approaches

National Research Council Canada - National Science Library

Lim, Lin

1997-01-01

Nanoplanktonic protists comprise a diverse assemblage of flagellate species. Current methods for identifying small protists do not readily permit identification and enumeration of nanoplanktonic flagellates in cultures or field samples...

[Application of anaerobic bacteria detection in oral and maxillofacial infection].

Science.gov (United States)

Bao, Zhen-ying; Lin, Qin; Meng, Yan-hong; He, Chun; Su, Jia-zeng; Peng, Xin

2016-02-18

To investigate the distribution and drug resistance of anaerobic bacteria in the patients with oral and maxillofacial infection. Aerobic and anaerobic bacteria cultures from 61 specimens of pus from the patients with oral and maxillofacial infection in the Department of Oral and Maxillofacial Surgery, Peking University School of Stomatology were identified. The culture type was evaluated by API 20A kit and drug resistance test was performed by Etest method. The clinical data and antibacterial agents for the treatment of the 61 cases were collected, and the final outcomes were recorded. The bacteria cultures were isolated from all the specimens, with aerobic bacteria only in 6 cases (9.8%), anaerobic bacteria only in 7 cases (11.5%), and both aerobic and anaerobic bacteria in 48 cases (78.7%). There were 55 infected cases (90.2%) with anaerobic bacteria, and 81 anaerobic bacteria stains were isolated. The highest bacteria isolation rate of Gram positive anaerobic bacteria could be found in Peptostreptococcus, Bifidobacterium and Pemphigus propionibacterium. No cefoxitin, amoxicillin/carat acid resistant strain was detected in the above three Gram positive anaerobic bacteria. The highest bacteria isolation rate of Gram negative anaerobic bacteria could be detected in Porphyromonas and Prevotella. No metronidazole, cefoxitin, amoxicillin/carat acid resistant strain was found in the two Gram negative anaerobic bacteria. In the study, 48 patients with oral and maxillofacial infection were treated according to the results of drug resistance testing, and the clinical cure rate was 81.3%. Mixed aerobic and anaerobic bacteria cultures are very common in most oral and maxillofacial infection patients. Anaerobic bacteria culture and drug resistance testing play an important role in clinical treatment.

Review on Nano SeleniumProduced by Bacteria

Directory of Open Access Journals (Sweden)

LI Ji-xiang

2014-12-01

Full Text Available Selenium (Se is a kind of essential trace element for people and animal, while ionic state of selenium is toxic with high concentrations and will cause the selenium pollution. Nano-selenium is stable, nontoxic with higher biological activity. Application of bacteria reducing selenite or selenate to biological nano-selenium has great potential in selenium pollution control and nano-selenium production. This review summarizes the research progress of the red elemental nano-selenium reduced by bacteria including characteristics and application of nano-selenium, effects of carbon and nitrogen source, oxygen, temperature and pH in bacteria nano-selenium production, and molecular mechanisms of nano-selenium reduced by bacteria.

Differential staining of bacteria: acid fast stain.

Science.gov (United States)

Reynolds, Jackie; Moyes, Rita B; Breakwell, Donald P

2009-11-01

Acid-fastness is an uncommon characteristic shared by the genera Mycobacterium (Section 10A) and Nocardia. Because of this feature, this stain is extremely helpful in identification of these bacteria. Although Gram positive, acid-fast bacteria do not take the crystal violet into the wall well, appearing very light purple rather than the deep purple of normal Gram-positive bacteria. (c) 2009 by John Wiley & Sons, Inc.

Transformation of gram positive bacteria by sonoporation

Science.gov (United States)

Yang, Yunfeng; Li, Yongchao

2014-03-11

The present invention provides a sonoporation-based method that can be universally applied for delivery of compounds into Gram positive bacteria. Gram positive bacteria which can be transformed by sonoporation include, for example, Bacillus, Streptococcus, Acetobacterium, and Clostridium. Compounds which can be delivered into Gram positive bacteria via sonoporation include nucleic acids (DNA or RNA), proteins, lipids, carbohydrates, viruses, small organic and inorganic molecules, and nano-particles.

Identification of Bacteria and the Effect on Compressive Strength of Concrete

Directory of Open Access Journals (Sweden)

Anneza L. H.

2016-01-01

Full Text Available This paper presents the species of bacteria used in this study as well as the effect of the bacteria on compressive strength of bioconcrete. Bioconcrete is not only more environmentally friendly but it is easy to procure. The objective of this research is to identify the ureolytic bacteria and sulphate reduction bacteria that have been isolated and further use the bacteria in concrete to determine the effect of bacteria on compressive strength. Identification of bacteria is conducted through Polymerase chain reaction (PCR method and DNA sequencing. The DNA of the bacteria was run through BLAST algorithm to determine the bacterial species.The bacteria were added into the concrete mix as a partial replacement of water. 3% of water is replaced by ureolytic bacteria and 5% of water is replaced by sulphate reduction bacteria. After running BLAST algorithm the bacteria were identified as Enterococcus faecalis (ureolytic bacteria and Bacillus sp (sulphate reduction bacteria. The result of the compressive strength for control is 36.0 Mpa. Partial replacement of 3% water by ureolytic bacteria has strength of 38.2Mpa while partial replacement of 5% of water by sulphate reduction bacteria has strength of 42.5Mpa. The significant increase of compressive strength with the addition of bacteria shows that bacteria play a significant role in the improvement of compressive strength.

NREL Scientists Model Methane-Eating Bacteria | News | NREL

Science.gov (United States)

Scientists Model Methane-Eating Bacteria News Release: NREL Scientists Model Methane-Eating Bacteria February 13, 2018 Nature is full of surprises - not to mention solutions. A research team ) recently explored the possibilities provided by the natural world by researching how the bacteria

Characterization of (per)chlorate-reducing bacteria

NARCIS (Netherlands)

Wolterink, A.F.W.M.

2004-01-01

Some bacteria can use (per)chlorateas terminal electron acceptor for growth. These bacteria convert perchlorate via chlorate and chlorite into chloride and molecular oxygen. Oxygen formation in microbial respiration is unique. In this study two chlorate-reducing strains

Fuzzy species among recombinogenic bacteria

Directory of Open Access Journals (Sweden)

Fraser Christophe

2005-03-01

Full Text Available Abstract Background It is a matter of ongoing debate whether a universal species concept is possible for bacteria. Indeed, it is not clear whether closely related isolates of bacteria typically form discrete genotypic clusters that can be assigned as species. The most challenging test of whether species can be clearly delineated is provided by analysis of large populations of closely-related, highly recombinogenic, bacteria that colonise the same body site. We have used concatenated sequences of seven house-keeping loci from 770 strains of 11 named Neisseria species, and phylogenetic trees, to investigate whether genotypic clusters can be resolved among these recombinogenic bacteria and, if so, the extent to which they correspond to named species. Results Alleles at individual loci were widely distributed among the named species but this distorting effect of recombination was largely buffered by using concatenated sequences, which resolved clusters corresponding to the three species most numerous in the sample, N. meningitidis, N. lactamica and N. gonorrhoeae. A few isolates arose from the branch that separated N. meningitidis from N. lactamica leading us to describe these species as 'fuzzy'. Conclusion A multilocus approach using large samples of closely related isolates delineates species even in the highly recombinogenic human Neisseria where individual loci are inadequate for the task. This approach should be applied by taxonomists to large samples of other groups of closely-related bacteria, and especially to those where species delineation has historically been difficult, to determine whether genotypic clusters can be delineated, and to guide the definition of species.

Antibacterial activity of silver-killed bacteria: the "zombies" effect

Science.gov (United States)

Wakshlak, Racheli Ben-Knaz; Pedahzur, Rami; Avnir, David

2015-04-01

We report a previously unrecognized mechanism for the prolonged action of biocidal agents, which we denote as the zombies effect: biocidally-killed bacteria are capable of killing living bacteria. The concept is demonstrated by first killing Pseudomonas aeruginosa PAO1 with silver nitrate and then challenging, with the dead bacteria, a viable culture of the same bacterium: Efficient antibacterial activity of the killed bacteria is observed. A mechanism is suggested in terms of the action of the dead bacteria as a reservoir of silver, which, due to Le-Chatelier's principle, is re-targeted to the living bacteria. Langmuirian behavior, as well as deviations from it, support the proposed mechanism.

Gastric spiral bacteria in small felids.

Science.gov (United States)

Kinsel, M J; Kovarik, P; Murnane, R D

1998-06-01

Nine small cats, including one bobcat (Felis rufus), one Pallas cat (F. manul), one Canada lynx (F. lynx canadensis), two fishing cats (F. viverrina), two margays (F. wiedii), and two sand cats (F. margarita), necropsied between June 1995 and March 1997 had large numbers of gastric spiral bacteria, whereas five large cats, including one African lion (Panthera leo), two snow leopards (P. uncia), one Siberian tiger (P. tigris altaica), and one jaguar (P. onca), necropsied during the same period had none. All of the spiral organisms from the nine small cats were histologically and ultrastructurally similar. Histologically, the spiral bacteria were 5-14 microm long with five to nine coils per organism and were located both extracellularly within gastric glands and surface mucus, and intracellularly in parietal cells. Spiral bacteria in gastric mucosal scrapings from the Canada lynx, one fishing cat, and the two sand cats were gram negative and had corkscrewlike to tumbling motility when viewed with phase contrast microscopy. The bacteria were 0.5-0.7 microm wide, with a periodicity of 0.65-1.1 microm in all cats. Bipolar sheathed flagella were occasionally observed, and no periplasmic fibrils were seen. The bacteria were extracellular in parietal cell canaliculi and intracellular within parietal cells. Culture of mucosal scrapings from the Canada lynx and sand cats was unsuccessful. Based on morphology, motility, and cellular tropism, the bacteria were probably Helicobacter-like organisms. Although the two margays had moderate lymphoplasmacytic gastritis, the other cats lacked or had only mild gastric lymphoid infiltrates, suggesting that these organisms are either commensals or opportunistic pathogens.

Catabolism of lysine by mixed rumen bacteria

International Nuclear Information System (INIS)

Onodera, Ryoji; Kandatsu, Makoto.

1975-01-01

Metabolites arising from the catabolism of lysine by the mixed rumen bacteria were chromatographically examined by using radioactive lysine. After 6 hr incubation, 241 nmole/ml of lysine was decomposed to give ether-soluble substances and CO 2 by the bacteria and 90 nmole/ml of lysine was incorporated unchanged into the bacteria. delta-Aminovalerate, cadaverine or pipecolate did not seem to be produced from lysine even after incubation of the bacteria with addition of those three amino compounds to trap besides lysine and radioactive lysine. Most of the ether-soluble substances produced from radioactive lysine was volatile fatty acids (VFAs). Fractionation of VFAs revealed that the peaks of butyric and acetic acids coincided with the strong radioactive peaks. Small amounts of radioactivities were detected in propionic acid peak and a peak assumed to be caproic acid. The rumen bacteria appeared to decompose much larger amounts of lysine than the rumen ciliate protozoa did. (auth.)

Biodiversity of Bacteria Isolated from Different Soils

Directory of Open Access Journals (Sweden)

Fatma YAMAN

2017-01-01

Full Text Available The aim of this study was to determine the biodiversity of PHB producing bacteria isolated from soils where fruit and vegetable are cultivated (onion, grape, olive, mulberry and plum in Aydın providence. Morphological, cultural, biochemical, and molecular methods were used for bacteria identification. These isolated bacteria were identified by 16S rRNA sequencing and using BLAST. The following bacteria Bacillus thuringiensis (6, Bacillus cereus (8, Bacillus anthrachis (1, Bacillus circulans (1, Bacillus weihenstephanensis (1, Pseudomonas putida (1, Azotobacter chroococcum (1, Brevibacterium frigoritolerans (1, Burkholderia sp. (1, Staphylococcus epidermidis (1, Streptomyces exfoliatus (1, Variovorax paradoxus (1 were found. The Maximum Likelihood method was used to produce a molecular phylogenetic analysis and a phylogenetic tree was constructed. These bacteria can produce polyhydroxybutyrate (PHB which is an organic polymer with commercial potential as a biodegradable thermoplastic. PHB can be used instead of petrol derivated non-degradable plastics. For this reason, PHB producing microorganisms are substantial in industry.

Probiotic bacteria: selective enumeration and survival in dairy foods.

Science.gov (United States)

Shah, N P

2000-04-01

A number of health benefits have been claimed for probiotic bacteria such as Lactobacillus acidophilus, Bifidobacterium spp., and Lactobacillus casei. Because of the potential health benefits, these organisms are increasingly incorporated into dairy foods. However, studies have shown low viability of probiotics in market preparations. In order to assess viability of probiotic bacteria, it is important to have a working method for selective enumeration of these probiotic bacteria. Viability of probiotic bacteria is important in order to provide health benefits. Viability of probiotic bacteria can be improved by appropriate selection of acid and bile resistant strains, use of oxygen impermeable containers, two-step fermentation, micro-encapsulation, stress adaptation, incorporation of micronutrients such as peptides and amino acids and by sonication of yogurt bacteria. This review will cover selective enumeration and survival of probiotic bacteria in dairy foods.

Seed-vectored endophytic bacteria modulate development of rice seedlings.

Science.gov (United States)

Verma, S K; Kingsley, K; Irizarry, I; Bergen, M; Kharwar, R N; White, J F

2017-06-01

The aim of the present study was to evaluate the effects of the removal of indigenous bacteria from rice seeds on seedling growth and development. Here we report the presence of three indigenous endophytic bacteria in rice seeds that play important roles in modulating seedling development (shoot and root lengths, and formation of root hairs and secondary roots) and defence against pathogens. Seed-associated bacteria were removed using surface sterilization with NaOCl (bleach) followed by antibiotic treatment. When bacteria were absent, growth of seedlings in terms of root hair development and overall seedling size was less than that of seedlings that contained bacteria. Reactive oxygen staining of seedlings showed that endophytic bacteria became intracellular in root parenchyma cells and root hairs. Roots containing endophytic bacteria were seen to stain densely for reactive oxygen, while roots free of bacteria stained lightly for reactive oxygen. Bacteria were isolated and identified as Enterobacter asburiae (VWB1), Pantoea dispersa (VWB2) and Pseudomonas putida (VWB3) by 16S rDNA sequencing. Bacteria were found to produce indole acetic acid (auxins), inhibited the pathogen Fusarium oxysporum and solubilized phosphate. Reinoculation of bacteria onto seedlings derived from surface-disinfected rice and Bermuda grass seeds significantly restored seedling growth and development. Rice seeds harbour indigenous bacterial endophytes that greatly influence seedling growth and development, including root and shoot lengths, root hair formation and disease susceptibility of rice seedlings. This study shows that seeds of rice naturally harbour bacterial endophytes that play key roles in modulation of seedling development. © 2017 The Society for Applied Microbiology.

Bacteria and plutonium in marine environments

International Nuclear Information System (INIS)

Carey, A.E.; Bowen, V.T.

1978-01-01

Microbes are important in geochemical cycling of many elements. Recent reports emphasize biogenous particulates and bacterial exometabolites as controlling oceanic distribution of plutonium. Bacteria perform oxidation/reduction reactions on metals such as mercury, nickel, lead, copper, and cadmium. Redox transformations or uptake of Pu by marine bacteria may well proceed by similar mechanisms. Profiles of water samples and sediment cores were obtained along the continental shelf off Nova Scotia and in the Gulf of St. Lawrence. Profiles of water samples, and sediment cores were obtained. Epifluorescent microscopy was used to view bacteria (from water or sediment) after concentration on membrane filters and staining with acridine orange. Radiochemical analyses measured Pu in sediments and water samples. Studies of 237 Pu uptake used a strain of Leucothrix mucor isolated from a macroalga. Enumeration shows bacteria to range 10 4 to 10 5 cells/ml in seawater or 10 7 to 10 8 cells/gram of sediment. These numbers are related to the levels and distrbution of Pu in the samples. In cultures of L. mucor amended with Pu atom concentrations approximating those present in open ocean environments, bacterial cells concentrated 237 Pu slower and to lower levels than did clay minerals, glass beads, or phytoplankton. These data further clarify the role of marine bacteria in Pu biogeochemistry

Assessment on Bacteria in the Heavy Metal Bioremediation

International Nuclear Information System (INIS)

Mohamad Romizan Osman; Mohamad Romizan Osman; Azman Azid; Kamaruzzaman Yunus; Ahmad Dasuki Mustafa; Mohammad Azizi Amran; Fazureen Azaman; Zarizal Suhaili; Yahya Abu Bakar; Syahrir Farihan Mohamed Zainuddin

2015-01-01

The aim of this study was to identify and verify the potential bacteria as the bioremediation agent. It involved bacteria isolation, identification through Gram staining, analytical profile index (API) test and determine bioremediation activities by using inductively coupled plasma mass spectrometry (ICPMS). The soil and water sample were collected from downstream of Galing River, Kuantan Malaysia. Based on phenotypic identification and biochemical analysis, the bacteria present at the vicinity area are possibility of Myroides spp. and Micrococcus spp. These bacteria were proven as bioremediation agent based on the ICPMS result. The result 1 ppm of Zink (Zn), Lead (Pb), Arsenic (As), Selenium (Se), Cadmium (Cd), Manganese (Mn), and Indium (In) dwindled after the bacteria inoculated and incubated for seven days in mixture of base salt media (BSM) with the heavy metal elements. Therefore, this proves that the bacteria which are present at downstream of Galing River, Kuantan Malaysia are significant to help us in the bioremediation activity to decrease the heavy metal pollution in the environment. (author)

Bacteria-based concrete: from concept to market

Science.gov (United States)

Wiktor, V.; Jonkers, H. M.

2016-08-01

The concept of self-healing concrete—a concrete which can autonomously repair itself after crack formation, with no or limited human intervention—has received a lot of attention over the past 10 years as it could help structures to last longer and at a lower maintenance cost. This paper gives an overview on the key aspects and recent advances in the development of the bacteria-based self-healing concrete developed at the University of Technology of Delft (The Netherlands). Research started with the screening and selection of concrete compatible bacteria and nutrients. Several types of encapsulated bacteria and nutrients have been developed and tested. The functionality of these healing agents was demonstrated by showing metabolic activity of activated bacterial spores by oxygen consumption measurements and by regain of material functionality in form of regain of water tightness. Besides development of bacteria-based self-healing concrete, a bacteria-based repair mortar and liquid system were developed for the treatment of aged concrete structures. Field trials have been carried out with either type of bacteria-based systems and the promising results have led to a spinoff company Basilisk Self-Healing Concrete with the aim to further develop these systems and bring them to the market.

Rapid diagnostics of the bacteria in air

Energy Technology Data Exchange (ETDEWEB)

Belov Nikolai, N. [ATECH KFT, Budapest (Hungary)

2000-07-01

Presence of the bacteria and viruses in the air is great problem now. Terrorists are going to use the bacteria weapon. Now biotechnology provides very cheap equipment ({approx} $500) for modification of the bacteria sorts. It may be used for receiving of new variants of the bacteriological weapon. And presence of one small bacteria aerosol generator in the international airport during several days will start the dangerous epidemic incidence the entire world. From another side - poor countries with hot and wet weather are continuously producing new and new dangerous bacteria. Every year epidemic waves of influence are going from China, India or Africa. And once up a time it will be epidemic explosive with fast lethal finish. Methods of estimation of the bio-aerosols in Air of City are very poor. Standard Bio-aerosol sampler has two conflicting demands. From one side the bio-sampler needs in great air volume of sample with great efficiency of separation of aerosol particles from measured air. From another side all selected particles needs in great care. This demand carried out from method of measurement of bacteria in sample by counting of colonies that grew from bacteria on nutrient media after incubation time. It is a problem to prevent bacterial flora from death during collecting aerosol sample. This time of growth and counting of colony is so long that result of this measurement will be unusable if it will be terrorist action of start of bacteriological was. Here presented new methods for fast diagnostics of the bacteria in the air. It consists from 4 general parts: (1) Micro-droplet method for diagnostics of biological active substances in aerosol sample. This method allows to control the bio-particle position on the plate, to use series of biochemistry species for analytical reaction for this small bio-particle. Small volume of biochemical reaction reduces noise. This method provides extremely high sensitivity for discovering of biological material. (2

Anti-bacteria effect of active ingredients of siraitia grosvenorii on the spoilage bacteria isolated from sauced pork head meat

Science.gov (United States)

Li, X.; Xu, L. Y.; Cui, Y. Q.; Pang, M. X.; Wang, F.; Qi, J. H.

2018-01-01

Extraction and anti-bacteria effect of active ingredients of Siraitia grosvenorii were studied in this paper. Extraction combined with ultrasonic was adopted. The optimum extraction condition was determined by single factor test; the anti-bacteria effect of active ingredients and minimum inhibitory concentration (MIC) were valued by Oxford-cup method. The results indicated that optimum extraction condition of active ingredients extracted from Siraitia grosvenorii were described as follows: ethanol concentrations of sixty-five percent and twenty minutes with ultrasonic assisted extraction; the active ingredients of Siraitia grosvenorii had anti-bacteria effect on Staphylococcus epidermidis, Proteus vulgaris, Bacillus sp, Serratia sp and MIC was 0.125g/mL, 0.0625g/mL, 0.125g/mL and 0.125g/mL. The active constituent of Siraitia grosvenorii has obvious anti-bacteria effect on the spoilage bacteria isolated from Sauced pork head meat and can be used as a new natural food preservation to prolong the shelf-life of Low-temperature meat products.

Rapid methods for detection of bacteria

DEFF Research Database (Denmark)

Corfitzen, Charlotte B.; Andersen, B.Ø.; Miller, M.

2006-01-01

Traditional methods for detection of bacteria in drinking water e.g. Heterotrophic Plate Counts (HPC) or Most Probable Number (MNP) take 48-72 hours to give the result. New rapid methods for detection of bacteria are needed to protect the consumers against contaminations. Two rapid methods...

Isolation and characterization of feather degrading bacteria from ...

African Journals Online (AJOL)

This study is aimed at isolating and characterizing new culturable feather degrading bacteria from soils of the University of Mauritius Farm. Bacteria that were isolated were tested for their capability to grow on feather meal agar (FMA). Proteolytic bacteria were tested for feather degradation and were further identified ...

Bacteria associated with cultures of psathyrella atroumbonata (Pleger)

African Journals Online (AJOL)

These bacteria include Bacillus licheniformis, Bacillus subtilis, Leuconostoc mesenteroides, Pseudomonas aeruginosa, Bacillus cereus and Staphylococcus aureus. The average bacteria count was 1.0 x 106 cfu/ml and these bacteria grew within pH range of 5.0 and 9.0. the optimum temperature range of growth lied ...

Thymidine kinase diversity in bacteria

DEFF Research Database (Denmark)

Sandrini, Michael; Clausen, A.R.; Munch-Petersen, B.

2006-01-01

Thymidine kinases (TKs) appear to be almost ubiquitous and are found in nearly all prokaryotes, eukaryotes, and several viruses. They are the key enzymes in thymidine salvage and activation of several anti-cancer and antiviral drugs. We show that bacterial TKs can be subdivided into 2 groups. The....... The TKs from Gram-positive bacteria are more closely related to the eukaryotic TK1 enzymes than are TKs from Gram-negative bacteria....

Characterization of Bacteria Associated with Pinewood Nematode Bursaphelenchus xylophilus

Science.gov (United States)

Vicente, Claudia S. L.; Nascimento, Francisco; Espada, Margarida; Barbosa, Pedro; Mota, Manuel; Glick, Bernard R.; Oliveira, Solange

2012-01-01

Pine wilt disease (PWD) is a complex disease integrating three major agents: the pathogenic agent, the pinewood nematode Bursaphelenchus xylophilus; the insect-vector Monochamus spp.; and the host pine tree, Pinus sp. Since the early 80's, the notion that another pathogenic agent, namely bacteria, may play a role in PWD has been gaining traction, however the role of bacteria in PWD is still unknown. The present work supports the possibility that some B. xylophilus-associated bacteria may play a significant role in the development of this disease. This is inferred as a consequence of: (i) the phenotypic characterization of a collection of 35 isolates of B. xylophilus-associated bacteria, in different tests broadly used to test plant pathogenic and plant growth promoting bacteria, and (ii) greenhouse experiments that infer the pathogenicity of these bacteria in maritime pine, Pinus pinaster. The results illustrate the presence of a heterogeneous microbial community associated with B. xylophilus and the traits exhibited by at least, some of these bacteria, appear to be related to PWD symptoms. The inoculation of four specific B. xylophilus-associated bacteria isolates in P. pinaster seedlings resulted in the development of some PWD symptoms suggesting that these bacteria likely play an active role with B. xylophilus in PWD. PMID:23091599

Identification of Lactic Acid Bacteria and Propionic Acid Bacteria using FTIR Spectroscopy and Artificial Neural Networks

Directory of Open Access Journals (Sweden)

Beata Nalepa

2012-01-01

Full Text Available In the present study, lactic acid bacteria and propionic acid bacteria have been identified at the genus level with the use of artificial neural networks (ANNs and Fourier transform infrared spectroscopy (FTIR. Bacterial strains of the genera Lactobacillus, Lactococcus, Leuconostoc, Streptococcus and Propionibacterium were analyzed since they deliver health benefits and are routinely used in the food processing industry. The correctness of bacterial identification by ANNs and FTIR was evaluated at two stages. At first stage, ANNs were tested based on the spectra of 66 reference bacterial strains. At second stage, the evaluation involved 286 spectra of bacterial strains isolated from food products, deposited in our laboratory collection, and identified by genus-specific PCR. ANNs were developed based on the spectra and their first derivatives. The most satisfactory results were reported for the probabilistic neural network, which was built using a combination of W5W4W3 spectral ranges. This network correctly identified the genus of 95 % of the lactic acid bacteria and propionic acid bacteria strains analyzed.

Rock-degrading endophytic bacteria in cacti

Science.gov (United States)

M. Esther Puente; Ching Y. Li; Yoav Bashan

2009-01-01

A plant-bacterium association of the cardon cactus (Pachycereus pringlei) and endophytic bacteria promotes establishment of seedlings and growth on igneous rocks without soil. These bacteria weather several rock types and minerals, unbind significant amounts of useful minerals for plants from the rocks, fix in vitro N2. produce...

Rapid separation of bacteria from blood - Chemical aspects.

Science.gov (United States)

Alizadeh, Mahsa; Wood, Ryan L; Buchanan, Clara M; Bledsoe, Colin G; Wood, Madison E; McClellan, Daniel S; Blanco, Rae; Ravsten, Tanner V; Husseini, Ghaleb A; Hickey, Caroline L; Robison, Richard A; Pitt, William G

2017-06-01

To rapidly diagnose infectious organisms causing blood sepsis, bacteria must be rapidly separated from blood, a very difficult process considering that concentrations of bacteria are many orders of magnitude lower than concentrations of blood cells. We have successfully separated bacteria from red and white blood cells using a sedimentation process in which the separation is driven by differences in density and size. Seven mL of whole human blood spiked with bacteria is placed in a 12-cm hollow disk and spun at 3000rpm for 1min. The red and white cells sediment more than 30-fold faster than bacteria, leaving much of the bacteria in the plasma. When the disk is slowly decelerated, the plasma flows to a collection site and the red and white cells are trapped in the disk. Analysis of the recovered plasma shows that about 36% of the bacteria is recovered in the plasma. The plasma is not perfectly clear of red blood cells, but about 94% have been removed. This paper describes the effects of various chemical aspects of this process, including the influence of anticoagulant chemistry on the separation efficiency and the use of wetting agents and platelet aggregators that may influence the bacterial recovery. In a clinical scenario, the recovered bacteria can be subsequently analyzed to determine their species and resistance to various antibiotics. Copyright © 2017 Elsevier B.V. All rights reserved.

Effects of symbiotic bacteria on chemical sensitivity of Daphnia magna.

Science.gov (United States)

Manakul, Patcharaporn; Peerakietkhajorn, Saranya; Matsuura, Tomoaki; Kato, Yasuhiko; Watanabe, Hajime

2017-07-01

The crustacean zooplankton Daphnia magna has been widely used for chemical toxicity tests. Although abiotic factors have been well documented in ecotoxicological test protocols, biotic factors that may affect the sensitivity to chemical compounds remain limited. Recently, we identified symbiotic bacteria that are critical for the growth and reproduction of D. magna. The presence of symbiotic bacteria on Daphnia raised the question as to whether these bacteria have a positive or negative effect on toxicity tests. In order to evaluate the effects of symbiotic bacteria on toxicity tests, bacteria-free Daphnia were prepared, and their chemical sensitivities were compared with that of Daphnia with symbiotic bacteria based on an acute immobilization test. The Daphnia with symbiotic bacteria showed higher chemical resistance to nonylphenol, fenoxycarb, and pentachlorophenol than bacteria-free Daphnia. These results suggested potential roles of symbiotic bacteria in the chemical resistance of its host Daphnia. Copyright © 2017 Elsevier Ltd. All rights reserved.

Comparative genomics of the lactic acid bacteria

Energy Technology Data Exchange (ETDEWEB)

Makarova, K.; Slesarev, A.; Wolf, Y.; Sorokin, A.; Mirkin, B.; Koonin, E.; Pavlov, A.; Pavlova, N.; Karamychev, V.; Polouchine, N.; Shakhova, V.; Grigoriev, I.; Lou, Y.; Rokhsar, D.; Lucas, S.; Huang, K.; Goodstein, D. M.; Hawkins, T.; Plengvidhya, V.; Welker, D.; Hughes, J.; Goh, Y.; Benson, A.; Baldwin, K.; Lee, J. -H.; Diaz-Muniz, I.; Dosti, B.; Smeianov, V; Wechter, W.; Barabote, R.; Lorca, G.; Altermann, E.; Barrangou, R.; Ganesan, B.; Xie, Y.; Rawsthorne, H.; Tamir, D.; Parker, C.; Breidt, F.; Broadbent, J.; Hutkins, R.; O' Sullivan, D.; Steele, J.; Unlu, G.; Saier, M.; Klaenhammer, T.; Richardson, P.; Kozyavkin, S.; Weimer, B.; Mills, D.

2006-06-01

Lactic acid-producing bacteria are associated with various plant and animal niches and play a key role in the production of fermented foods and beverages. We report nine genome sequences representing the phylogenetic and functional diversity of these bacteria. The small genomes of lactic acid bacteria encode a broad repertoire of transporters for efficient carbon and nitrogen acquisition from the nutritionally rich environments they inhabit and reflect a limited range of biosynthetic capabilities that indicate both prototrophic and auxotrophic strains. Phylogenetic analyses, comparison of gene content across the group, and reconstruction of ancestral gene sets indicate a combination of extensive gene loss and key gene acquisitions via horizontal gene transfer during the coevolution of lactic acid bacteria with their habitats.

Chitin Degradation In Marine Bacteria

DEFF Research Database (Denmark)

Paulsen, Sara; Machado, Henrique; Gram, Lone

2015-01-01

Introduction: Chitin is the most abundant polymer in the marine environment and the second most abundant in nature. Chitin does not accumulate on the ocean floor, because of microbial breakdown. Chitin degrading bacteria could have potential in the utilization of chitin as a renewable carbon...... and nitrogen source in the fermentation industry.Methods: Here, whole genome sequenced marine bacteria were screened for chitin degradation using phenotypic and in silico analyses.Results: The in silico analyses revealed the presence of three to nine chitinases in each strain, however the number of chitinases...... chitin regulatory system.Conclusions: This study has provided insight into the ecology of chitin degradation in marine bacteria. It also served as a basis for choosing a more efficient chitin degrading production strain e.g. for the use of chitin waste for large-scale fermentations....

Mortality of fecal bacteria in seawater

International Nuclear Information System (INIS)

Garcia-Lara, J.; Menon, P.; Servais, P.; Billen, G.

1991-01-01

The authors propose a method for determining the mortality rate for allochthonous bacteria released in aquatic environments without interference due to the loss of culturability in specific culture media. This method consists of following the disappearance of radioactivity from the trichloracetic acid-insoluble fraction in water samples to which [ 3 H]thymidine-prelabeled allochthonous bacteria have been added. In coastal seawater, they found that the actual rate of disappearance of fecal bacteria was 1 order of magnitude lower than the rate of loss of culturability on specific media. Minor adaptation of the procedure may facilitate assessment of the effect of protozoan grazing and bacteriophage lysis on the overall bacterial mortality rate

Beer spoilage bacteria and hop resistance.

Science.gov (United States)

Sakamoto, Kanta; Konings, Wil N

2003-12-31

For brewing industry, beer spoilage bacteria have been problematic for centuries. They include some lactic acid bacteria such as Lactobacillus brevis, Lactobacillus lindneri and Pediococcus damnosus, and some Gram-negative bacteria such as Pectinatus cerevisiiphilus, Pectinatus frisingensis and Megasphaera cerevisiae. They can spoil beer by turbidity, acidity and the production of unfavorable smell such as diacetyl or hydrogen sulfide. For the microbiological control, many advanced biotechnological techniques such as immunoassay and polymerase chain reaction (PCR) have been applied in place of the conventional and time-consuming method of incubation on culture media. Subsequently, a method is needed to determine whether the detected bacterium is capable of growing in beer or not. In lactic acid bacteria, hop resistance is crucial for their ability to grow in beer. Hop compounds, mainly iso-alpha-acids in beer, have antibacterial activity against Gram-positive bacteria. They act as ionophores which dissipate the pH gradient across the cytoplasmic membrane and reduce the proton motive force (pmf). Consequently, the pmf-dependent nutrient uptake is hampered, resulting in cell death. The hop-resistance mechanisms in lactic acid bacteria have been investigated. HorA was found to excrete hop compounds in an ATP-dependent manner from the cell membrane to outer medium. Additionally, increased proton pumping by the membrane bound H(+)-ATPase contributes to hop resistance. To energize such ATP-dependent transporters hop-resistant cells contain larger ATP pools than hop-sensitive cells. Furthermore, a pmf-dependent hop transporter was recently presented. Understanding the hop-resistance mechanisms has enabled the development of rapid methods to discriminate beer spoilage strains from nonspoilers. The horA-PCR method has been applied for bacterial control in breweries. Also, a discrimination method was developed based on ATP pool measurement in lactobacillus cells. However

Inhibitory effect of bacteriocin-producing lactic acid bacteria against histamine-forming bacteria isolated from Myeolchi-jeot

Directory of Open Access Journals (Sweden)

Eun-Seo Lim

2016-12-01

Full Text Available Abstract The objectives of this study were to identify the histamine-forming bacteria and bacteriocin- producing lactic acid bacteria (LAB isolated from Myeolchi-jeot according to sequence analysis of the 16S rRNA gene, to evaluate the inhibitory effects of the bacteriocin on the growth and histamine accumulation of histamine-forming bacteria, and to assess the physico-chemical properties of the bacteriocin. Based on 16S rRNA gene sequences, histamine-forming bacteria were identified as Bacillus licheniformis MCH01, Serratia marcescens MCH02, Staphylococcus xylosus MCH03, Aeromonas hydrophila MCH04, and Morganella morganii MCH05. The five LAB strains identified as Pediococcus acidilactici MCL11, Leuconostoc mesenteroides MCL12, Enterococcus faecium MCL13, Lactobacillus sakei MCL14, and Lactobacillus acidophilus MCL15 were found to produce an antibacterial compound with inhibitory activity against the tested histamine-producing bacteria. The inhibitory activity of these bacteriocins obtained from the five LAB remained stable after incubation at pH 4.0–8.0 and heating for 10 min at 80 °C; however, the bacteriocin activity was destroyed after treatment with papain, pepsin, proteinase K, α-chymotrypsin, or trypsin. Meanwhile, these bacteriocins produced by the tested LAB strains also exhibited histamine-degradation ability. Therefore, these antimicrobial substances may play a role in inhibiting histamine formation in the fermented fish products and preventing seafood-related food-borne disease caused by bacterially generated histamine.

Anaerobic bacteria that dechlorinate perchloroethene.

Science.gov (United States)

Fathepure, B Z; Nengu, J P; Boyd, S A

1987-01-01

In this study, we identified specific cultures of anaerobic bacteria that dechlorinate perchlorethene (PCE). The bacteria that significantly dechlorinated PCE were strain DCB-1, an obligate anaerobe previously shown to dechlorinate chlorobenzoate, and two strains of Methanosarcina. The rate of PCE dechlorination by DCB-1 compared favorably with reported rates of trichloroethene bio-oxidation by methanotrophs. Even higher PCE dechlorination rates were achieved when DCB-1 was grown in a methanogenic consortium. PMID:3426224

Modulation of immune homeostasis by commensal bacteria

Science.gov (United States)

Ivanov, Ivaylo I.; Littman, Dan R.

2011-01-01

Intestinal bacteria form a resident community that has co-evolved with the mammalian host. In addition to playing important roles in digestion and harvesting energy, commensal bacteria are crucial for the proper functioning of mucosal immune defenses. Most of these functions have been attributed to the presence of large numbers of “innocuous” resident bacteria that dilute or occupy niches for intestinal pathogens or induce innate immune responses that sequester bacteria in the lumen, thus quenching excessive activation of the mucosal immune system. However it has recently become obvious that commensal bacteria are not simply beneficial bystanders, but are important modulators of intestinal immune homeostasis and that the composition of the microbiota is a major factor in pre-determining the type and robustness of mucosal immune responses. Here we review specific examples of individual members of the microbiota that modify innate and adaptive immune responses, and we focus on potential mechanisms by which such species-specific signals are generated and transmitted to the host immune system. PMID:21215684

Uptake of americium-241 by algae and bacteria

Energy Technology Data Exchange (ETDEWEB)

Geisy, J P; Paine, D

1978-01-01

Algae and bacteria are important factors in the transport and mobilization of elements in the biosphere. These factors may be involved in trophic biomagnification, resulting in a potential human hazard or environmental degradation. Although americium, one of the most toxic elements known, is not required for plant growth, it may be concentrated by algae and bacteria. Therefore, the availability of americium-241 to algae and bacteria was studied to determine their role in the ultimate fate of this element released into the environment. Both algae and bacteria concentrated americium-241 to a high degree, making them important parts of the biomagnification process. The ability to concentrate americium-241 makes algae and bacteria potentially significant factors in cycling this element in the water column. (4 graphs, numerous references, 3 tables)

High motility reduces grazing mortality of planktonic bacteria

DEFF Research Database (Denmark)

Matz, Carsten; Jurgens, K.

2005-01-01

We tested the impact of bacterial swimming speed on the survival of planktonic bacteria in the presence of protozoan grazers. Grazing experiments with three common bacterivorous nanoflagellates revealed low clearance rates for highly motile bacteria. High-resolution video microscopy demonstrated...... size revealed highest grazing losses for moderately motile bacteria with a cell size between 0.2 and 0.4 mum(3). Grazing mortality was lowest for cells of >0.5 mum(3) and small, highly motile bacteria. Survival efficiencies of >95% for the ultramicrobacterial isolate CP-1 (less than or equal to0.1 mum......(3), >50 mum s(-1)) illustrated the combined protective action of small cell size and high motility. Our findings suggest that motility has an important adaptive function in the survival of planktonic bacteria during protozoan grazing....

Thermophilic Sulfate-Reducing Bacteria in Cold Marine Sediment

DEFF Research Database (Denmark)

ISAKSEN, MF; BAK, F.; JØRGENSEN, BB

1994-01-01

sulfate-reducing bacteria was detected. Time course experiments showed constant sulfate reduction rates at 4 degrees C and 30 degrees C, whereas the activity at 60 degrees C increased exponentially after a lag period of one day. Thermophilic, endospore-forming sulfate-reducing bacteria, designated strain...... C to search for presence of psychrophilic, mesophilic and thermophilic sulfate-reducing bacteria. Detectable activity was initially only in the mesophilic range, but after a lag phase sulfate reduction by thermophilic sulfate-reducing bacteria were observed. No distinct activity of psychrophilic...... P60, were isolated and characterized as Desulfotomaculum kuznetsovii. The temperature response of growth and respiration of strain P60 agreed well with the measured sulfate reduction at 50 degrees-70 degrees C. Bacteria similar to strain P60 could thus be responsible for the measured thermophilic...

Thermophilic Sulfate-Reducing Bacteria in Cold Marine Sediment

DEFF Research Database (Denmark)

ISAKSEN, MF; BAK, F.; JØRGENSEN, BB

1994-01-01

C to search for presence of psychrophilic, mesophilic and thermophilic sulfate-reducing bacteria. Detectable activity was initially only in the mesophilic range, but after a lag phase sulfate reduction by thermophilic sulfate-reducing bacteria were observed. No distinct activity of psychrophilic...... sulfate-reducing bacteria was detected. Time course experiments showed constant sulfate reduction rates at 4 degrees C and 30 degrees C, whereas the activity at 60 degrees C increased exponentially after a lag period of one day. Thermophilic, endospore-forming sulfate-reducing bacteria, designated strain...... P60, were isolated and characterized as Desulfotomaculum kuznetsovii. The temperature response of growth and respiration of strain P60 agreed well with the measured sulfate reduction at 50 degrees-70 degrees C. Bacteria similar to strain P60 could thus be responsible for the measured thermophilic...

Visualizing aquatic bacteria by light and transmission electron microscopy.

Science.gov (United States)

Silva, Thiago P; Noyma, Natália P; Duque, Thabata L A; Gamalier, Juliana P; Vidal, Luciana O; Lobão, Lúcia M; Chiarini-Garcia, Hélio; Roland, Fábio; Melo, Rossana C N

2014-01-01

The understanding of the functional role of aquatic bacteria in microbial food webs is largely dependent on methods applied to the direct visualization and enumeration of these organisms. While the ultrastructure of aquatic bacteria is still poorly known, routine observation of aquatic bacteria by light microscopy requires staining with fluorochromes, followed by filtration and direct counting on filter surfaces. Here, we used a new strategy to visualize and enumerate aquatic bacteria by light microscopy. By spinning water samples from varied tropical ecosystems in a cytocentrifuge, we found that bacteria firmly adhere to regular slides, can be stained by fluorochoromes with no background formation and fast enumerated. Significant correlations were found between the cytocentrifugation and filter-based methods. Moreover, preparations through cytocentrifugation were more adequate for bacterial viability evaluation than filter-based preparations. Transmission electron microscopic analyses revealed a morphological diversity of bacteria with different internal and external structures, such as large variation in the cell envelope and capsule thickness, and presence or not of thylakoid membranes. Our results demonstrate that aquatic bacteria represent an ultrastructurally diverse population and open avenues for easy handling/quantification and better visualization of bacteria by light microscopy without the need of filter membranes.

Microfluidic Transducer for Detecting Nanomechanical Movements of Bacteria

Science.gov (United States)

Kara, Vural; Ekinci, Kamil

2017-11-01

Various nanomechanical movements of bacteria are currently being explored as an indication of bacterial viability. Most notably, these movements have been observed to subside rapidly and dramatically when the bacteria are exposed to an effective antibiotic. This suggests that monitoring bacterial movements, if performed with high fidelity, can offer a path to various clinical microbiological applications, including antibiotic susceptibility tests. Here, we introduce a robust and sensitive microfluidic transduction technique for detecting the nanomechanical movements of bacteria. The technique is based on measuring the electrical fluctuations in a microchannel which the bacteria populate. These electrical fluctuations are caused by the swimming of motile, planktonic bacteria and random oscillations of surface-immobilized bacteria. The technique provides enough sensitivity to detect even the slightest movements of a single cell and lends itself to smooth integration with other microfluidic methods and devices; it may eventually be used for rapid antibiotic susceptibility testing. We acknowledge support from Boston University Office of Technology Development, Boston University College of Engineering, NIH (1R03AI126168-01) and The Wallace H. Coulter Foundation.

Exogenous fatty acid metabolism in bacteria.

Science.gov (United States)

Yao, Jiangwei; Rock, Charles O

2017-10-01

Bacterial type II fatty acid synthesis (FASII) is a target for novel antibiotic development. All bacteria encode for mechanisms to incorporate exogenous fatty acids, and some bacteria can use exogenous fatty acids to bypass FASII inhibition. Bacteria encode three different mechanisms for activating exogenous fatty acids for incorporation into phospholipid synthesis. Exogenous fatty acids are converted into acyl-CoA in Gammaproteobacteria such as E. coli. Acyl-CoA molecules constitute a separate pool from endogenously synthesized acyl-ACP. Acyl-CoA can be used for phospholipid synthesis or broken down by β-oxidation, but cannot be used for lipopolysaccharide synthesis. Exogenous fatty acids are converted into acyl-ACP in some Gram-negative bacteria. The resulting acyl-ACP undergoes the same fates as endogenously synthesized acyl-ACP. Exogenous fatty acids are converted into acyl-phosphates in Gram-positive bacteria, and can be used for phospholipid synthesis or become acyl-ACP. Only the order Lactobacillales can use exogenous fatty acids to bypass FASII inhibition. FASII shuts down completely in presence of exogenous fatty acids in Lactobacillales, allowing Lactobacillales to synthesize phospholipids entirely from exogenous fatty acids. Inhibition of FASII cannot be bypassed in other bacteria because FASII is only partially down-regulated in presence of exogenous fatty acid or FASII is required to synthesize essential metabolites such as β-hydroxyacyl-ACP. Certain selective pressures such as FASII inhibition or growth in biofilms can select for naturally occurring one step mutations that attenuate endogenous fatty acid synthesis. Although attempts have been made to estimate the natural prevalence of these mutants, culture-independent metagenomic methods would provide a better estimate. Copyright © 2017 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.

Sensitivity of certain bacteria to antibiotics and irradiation

Energy Technology Data Exchange (ETDEWEB)

Harsojo,; Andini, L S; Siagian, E G; Lina, M R; Zuleiha, S [National Atomic Energy Agency, Jakarta (Indonesia). Pasar Djumat Research Centre

1981-07-01

An experiment has been conducted to find vegetative forms of certain bacteria in Indonesia which are resistant to irradiation, the resistance of which will be compared to that of known radioresistant bacteria micrococcus radiodurans. To inactivate the vegetative forms of resistant bacteria to irradiation high doses are needed, while for storage purposes lower doses change the physical and chemical properties of the stored commodity are preferred. For this purpose the bacteria were irradiated in aerobic condition with gamma radiation doses of 0.1, 0.2 and 0.3 kGy, or treated with antibiotics e.g. tetracycline HCl or chloramphenicol with concentrations of 0.1, 0.2 and 0.3 ..mu..g/ml respectively. The results indicated that doses of 0.2 kGy and 0.1 ..mu..g/ml reduced the ability of the bacteria for multiplication.

Early decomposer assemblages of soil organisms in litterbags with vetch and rye roots

DEFF Research Database (Denmark)

Georgieva, Slavka; Christensen, Søren; Petersen, Henning

2005-01-01

and predatory nematodes (the intraguild predator) protozoa (the intraguild prey) and bacteria (the common prey). The much higher fungal biomass in rye than in vetch litterbags was not reflected in the biomass of the fungal feeders. Due to the generally lower intrinsic rate of increase of the fungivores, as well...... as of the omnivores and predators, in comparison with the bacterial feeders, they were not able to generate dense populations at this early stage of decomposition....... relationship to flagellated protozoa. This suggests that these nematodes controlled the protozoan biomass constituting a lower fraction of the bacterivore biomass in vetch compared to in rye. Such intraguild predator-prey relationship is therefore indicated for microbivorous organisms among bacterivorous...

Anti-bacteria Effect of Active Ingredients of Cacumen Platycladi on the Spoilage Bacteria of Sauced Pork Head Meat

Science.gov (United States)

Li, Xiao; Xu, Lingyi; Cui, Yuqian; Pang, Meixia; Wang, Fang; Qi, Jinghua

2017-12-01

Extraction and anti-bacteria effect of active ingredients of Cacumen Platycladi were studied in this paper. Extraction combined with ultrasonic was adopted. The optimum extraction condition was determined by single factor test; the anti-bacteria effect of active ingredients and minimum inhibitory concentration(MIC) were valued by Oxford-cup method. The results indicated that kaempferol was the active ingredients of Cacumen Platycladi whose optimum extraction condition for ethanol concentrations were sixty-five percent and twenty minutes with ultrasonic assisted extraction.; the active ingredients of Cacumen Platycladi had anti-bacteria effect on Staphylococcus, Proteus, Bacillus, Serratia and MIC was 0.5 g/mL,0.5 g/mL,0.0313 g/mL and 0.0625 g/mL. The active constituent of Cacumen Platycladi is kaempferol which has obvious anti-bacteria effect and can be used to prolong the shelf-life of Low-temperature meat products.

Behavior of plutonium interacting with bentonite and sulfate-reducing anaerobic bacteria

International Nuclear Information System (INIS)

Kudo, A.; Zheng, J.; Cayer, I.; Fujikawa, Y.; Yoshikawa, H.; Ito, M.

1997-01-01

The interactions between sulfate reducing anaerobic bacteria and plutonium, with or without bentonite present, were investigated using distribution coefficients [Kd (ml/g)] as an index of the radionuclide behavior. Plutonium Kds for living bacteria varied within a large range, from 1,804 to 112,952, depending on the pH, while the Kds ranged from 1,180 to 5,931 for dead bacteria. In general, living bacteria had higher plutonium Kds than dead bacteria. Furthermore, the higher Kd values of 39,677 to 106,915 for living bacteria were obtained for a pH range between 6.83 and 8.25, while no visible pH effect was observed for dead bacteria. These Kd values were obtained using tracers for both 236 Pu and 239 Pu, which can check the experimental procedures and mass balance. Another comparison was conducted for plutonium Kd values of mixtures of living bacteria with bentonite and sterilized bacteria with bentonite. The range of Kd values for the non-sterilized bacteria with bentonite were 1,194 to 83,648 while Kd values for the sterilized bacteria with bentonite were from 624 to 17,236. Again, the Kd values for the living bacteria with bentonite were higher than those of sterilized bacteria with bentonite. In other words, the presence of living anaerobic bacteria with bentonite increased, by roughly 50 times, the Kd values of 239 Pu when compared to the mixture of dead bacteria with bentonite. The results indicate that the effects of anaerobic bacteria within the engineered barrier system (in this case bentonite) will play a significant role in the behavior of plutonium in geologic repositories

Multiresistant Bacteria Isolated from Chicken Meat in Austria

Directory of Open Access Journals (Sweden)

Gernot Zarfel

2014-12-01

Full Text Available Multidrug resistant bacteria (MDR bacteria, such as extended spectrum beta-lactamase (ESBL Enterobacteriaceae, methicillin resistant Staphylococcus aureus (MRSA, and vancomycin-resistant Enterococci (VRE, pose a challenge to the human health care system. In recent years, these MDR bacteria have been detected increasingly outside the hospital environment. Also the contamination of food with MDR bacteria, particularly of meat and meat products, is a concern. The aim of the study was to evaluate the occurrence of MDR bacteria in chicken meat on the Austrian market. For this study, 50 chicken meat samples were analysed. All samples originated from chickens slaughtered in Austrian slaughterhouses and were marked as produced in Austria. Samples were analysed for the presence of ESBL Enterobacteriaceae, methicillin resistant Staphylococci and VRE. Resistance genes of the isolated bacteria were characterised by PCR and sequencing. In the present study 26 ESBL producing E. coli, five mecA gene harbouring Staphylococci (but no MRSA, and four VRE were detected in chicken meat samples of Austrian origin. In 24 (48% of the samples no ESBL Enterobacteriaceae, MRSA, methicillin resistant coagulase negative Staphylococcus (MRCNS or VRE could be detected. None of the samples contained all three types of investigated multiresistant bacteria. In concordance to previous studies, CTX-M-1 and SHV-12 were the dominant ESBL genes.

Pu sorption to activated conglomerate anaerobic bacteria

International Nuclear Information System (INIS)

Sasaki, Takayuki; Kudo, Akira

2001-01-01

The sorption of Pu to the anaerobic bacteria activated under specific conditions of temperature, pH and depleted nutrients after long dormant period was investigated. After 4 h at neutral pH, the distribution coefficient (K d ) between bacteria and aqueous phase at 308 and 278 K had around 10 3 to 10 4 . After over 5 days, however, the K d at only 308 K had increased to over 10 5 . Sterilized (dead) and dormant anaerobic bacteria adsorbed Pu to the same extent. (author)

The effect of lactic acid bacteria on cocoa bean fermentation.

Science.gov (United States)

Ho, Van Thi Thuy; Zhao, Jian; Fleet, Graham

2015-07-16

Cocoa beans (Theobroma cacao L.) are the raw material for chocolate production. Fermentation of cocoa pulp by microorganisms is crucial for developing chocolate flavor precursors. Yeasts conduct an alcoholic fermentation within the bean pulp that is essential for the production of good quality beans, giving typical chocolate characters. However, the roles of bacteria such as lactic acid bacteria and acetic acid bacteria in contributing to the quality of cocoa bean and chocolate are not fully understood. Using controlled laboratory fermentations, this study investigated the contribution of lactic acid bacteria to cocoa bean fermentation. Cocoa beans were fermented under conditions where the growth of lactic acid bacteria was restricted by the use of nisin and lysozyme. The resultant microbial ecology, chemistry and chocolate quality of beans from these fermentations were compared with those of indigenous (control) fermentations. The yeasts Hanseniaspora guilliermondii, Pichia kudriavzevii, Kluyveromyces marxianus and Saccharomyces cerevisiae, the lactic acid bacteria Lactobacillus plantarum, Lactobacillus pentosus and Lactobacillus fermentum and the acetic acid bacteria Acetobacter pasteurianus and Gluconobacter frateurii were the major species found in control fermentations. In fermentations with the presence of nisin and lysozyme, the same species of yeasts and acetic acid bacteria grew but the growth of lactic acid bacteria was prevented or restricted. These beans underwent characteristic alcoholic fermentation where the utilization of sugars and the production of ethanol, organic acids and volatile compounds in the bean pulp and nibs were similar for beans fermented in the presence of lactic acid bacteria. Lactic acid was produced during both fermentations but more so when lactic acid bacteria grew. Beans fermented in the presence or absence of lactic acid bacteria were fully fermented, had similar shell weights and gave acceptable chocolates with no differences

Comparative Genomics of Green Sulfur Bacteria

DEFF Research Database (Denmark)

Ussery, David; Davenport, C; Tümmler, B

2010-01-01

Eleven completely sequenced Chlorobi genomes were compared in oligonucleotide usage, gene contents, and synteny. The green sulfur bacteria (GSB) are equipped with a core genome that sustains their anoxygenic phototrophic lifestyle by photosynthesis, sulfur oxidation, and CO(2) fixation. Whole...... weight of 10(6), and are probably instrumental for the bacteria to generate their own intimate (micro)environment....

Isolation of radiation-resistant bacteria without exposure to irradiation

International Nuclear Information System (INIS)

Sanders, S.W.; Maxcy, R.B.

1979-01-01

Resistance to desiccation was utilized in the selection of highly radiation-resistant asporogenous bacteria from nonirradiated sources. A bacterial suspension in phosphate buffer was dried in a thin film at 25 0 C and 33% relative humidity. Storage under these conditions for 15 days or more reduced the number of radiation-sensitive bacteria. Further selection for radiation-resistant bacteria was obtained by irradiation of bacteria on velveteen in the replication process, therby avoiding the toxic effect of irradiated media. The similarity of radiation resistance and identifying characteristics in irradiated and non-irradiated isolates should allay some concerns that highly radiation-resistance bacteria have been permanently altered by radiation selection

Do Bacteria Age?

Indian Academy of Sciences (India)

Bacteria are thought to be examples of organisms that do not age. They divide by .... carry genetic material to the next generation through the process of reproduction; they are also .... molecules, and modified proteins. This report revealed that ...

Magnetosome chain superstructure in uncultured magnetotactic bacteria

International Nuclear Information System (INIS)

Abraçado, Leida G; Farina, Marcos; Abreu, Fernanda; Keim, Carolina N; Lins, Ulysses; Campos, Andrea P C

2010-01-01

Magnetotactic bacteria produce magnetosomes, which are magnetic particles enveloped by biological membranes, in a highly controlled mineralization process. Magnetosomes are used to navigate in magnetic fields by a phenomenon called magnetotaxis. Two levels of organization and control are recognized in magnetosomes. First, magnetotactic bacteria create a spatially distinct environment within vesicles defined by their membranes. In the vesicles, the bacteria control the size, composition and purity of the mineral content of the magnetic particles. Unique crystal morphologies are produced in magnetosomes as a consequence of this bacterial control. Second, magnetotactic bacteria organize the magnetosomes in chains within the cell body. It has been shown in a particular case that the chains are positioned within the cell body in specific locations defined by filamentous cytoskeleton elements. Here, we describe an additional level of organization of the magnetosome chains in uncultured magnetotactic cocci found in marine and freshwater sediments. Electron microscopy analysis of the magnetosome chains using a goniometer showed that the magnetic crystals in both types of bacteria are not oriented at random along the crystal chain. Instead, the magnetosomes have specific orientations relative to the other magnetosomes in the chain. Each crystal is rotated either 60°, 180° or 300° relative to their neighbors along the chain axis, causing the overlapping of the (1 1 1) and (1-bar 1-bar 1-bar) capping faces of neighboring crystals. We suggest that genetic determinants that are not present or active in bacteria with magnetosomes randomly rotated within a chain must be present in bacteria that organize magnetosomes so precisely. This particular organization may also be used as an indicative biosignature of magnetosomes in the study of magnetofossils in the cases where this symmetry is observed

Platelets and infections—complex interactions with bacteria

Directory of Open Access Journals (Sweden)

Hind eHAMZEH-COGNASSE

2015-02-01

Full Text Available Platelets can be considered sentinels of vascular system due to their high number in the circulation and to the range of functional immunoreceptors they express. Platelets express a wide range of potential bacterial receptors, including complement receptors, FcγRII, Toll-Like Receptors but also integrins conventionally described in the hemostatic response, such as GPIIb-IIIa or GPIb. Bacteria bind these receptors either directly, or indirectly via fibrinogen, fibronectin, the first complement C1q, the von Willebrand Factor, etc. The fate of platelet bound bacteria is questioned. Several studies reported the ability of activated platelets to internalize bacteria such as Staphylococcus aureus or Porphyromonas gingivalis, though there is no clue on what happens thereafter. Are they sheltered from the immune system in the cytoplasm of platelets or are they lysed? Indeed, while the presence of phagolysosome has not been demonstrated in platelets, they contain antimicrobial peptides that were shown to be efficient on S. aureus. Besides, the fact that bacteria can bind to platelets via receptors involved in hemostasis suggests that they may induce aggregation; this has indeed been described for Streptococcus sanguinis, S. epidermidis or C. pneumoniae. On the other hand, platelets are able to display an inflammatory response to an infectious triggering. We, and others, have shown that platelet release soluble immunomodulatory factors upon stimulation by bacterial components. Moreover, interactions between bacteria and platelets are not limited to only these two partners. Indeed, platelets are also essential for the formation of Neutrophil Extracellular Traps by neutrophils, resulting in bacterial clearance by trapping bacteria and concentrating antibacterial factors but in enhancing thrombosis. In conclusion, the platelet-bacteria interplay is a complex game; its fine analysis is complicated by the fact that the inflammatory component adds to the

Nanotextile membranes for bacteria Escherichia coli capturing

Directory of Open Access Journals (Sweden)

Jaroslav Lev

2010-01-01

Full Text Available The article describes an experimental study dealing with the possibility of nanotextile materials usa­ge for microbiologically contaminated water filtration. The aim of the study is to verify filtration ability of different nanotextile materials and evaluate the possibilities of practical usage. Good detention ability of these materials in the air filtration is the presumption for nanotextile to be used for bacteria filtration from a liquid. High nanotextile porosity with the nanotextile pores dimensions smaller than a bacteria size predicates the possibility of a successful usage of these materials. For the experiment were used materials made from electrospinning nanofibres under the label PA612, PUR1, PUR2 s PUR3 on the supporting unwoven textiles (viscose and PP. As a model simulation of the microbial contamination, bacteria Escherichia coli was chosen. Contaminated water was filtered during the overpressure activity of 105Pa on the input side of the filter from the mentioned material. After three-day incubation on the nutrient medium, cultures found in the samples before and after filtration were compared. In the filtrated water, bacteria E. coli were indicated, which did not verify the theoretical presumptions about an absolut bacteria detention. However, used materials caught at least 94% of bacteria in case of material PUR1 and up to 99,996% in case of material PUR2. These results predict the possibility of producing effective nanotextile filters for microbiologically contaminated water filtration.Recommendation: For the production of materials with better filtrating qualities, experiments need to be done, enabling better understanding of the bacteria detention mechanisms on the nanotextile material, and parameters of the used materials that influence the filtrating abilities need to be verified.

[Spectrum and susceptibility of preoperative conjunctival bacteria].

Science.gov (United States)

Fernández-Rubio, M E; Cuesta-Rodríguez, T; Urcelay-Segura, J L; Cortés-Valdés, C

2013-12-01

To describe the conjunctival bacterial spectrum of our patients undergoing intraocular surgery and their antibiotic sensitivity during the study period. A retrospective study of preoperative conjunctival culture of patients consecutively scheduled for intraocular surgery from 21 February 2011 to 1 April 2013. Specimens were directly seeded onto blood-agar and MacConkey-agar (aerobiosis incubation, 2 days), and on chocolate-agar (6% CO2 incubation, 7 days). The identified bacteria were divided into 3 groups according to their origin; the bacteria susceptibility tests were performed on those more pathogenic and on some of the less pathogenic when more than 5 colonies were isolated. The sensitivity of the exigent growing bacteria was obtained with disk diffusion technique, and for of the non-exigent bacteria by determining their minimum inhibitory concentration. The Epidat 3.1 program was used for statistical calculations. A total of 13,203 bacteria were identified in 6,051 cultures, with 88.7% being typical colonizers of conjunctiva (group 1), 8.8% typical of airways (group 2), and the remaining 2.5% of undetermined origin (group 3). 530 cultures (8.8%) were sterile. The sensitivity of group 1 was: 99% vancomycin, 95% rifampicin, 87% chloramphenicol, 76% tetracycline. Levels of co-trimoxazole, aminoglycosides, quinolones, β-lactams and macrolides decreased since 2007. The group 2 was very sensitive to chloramphenicol, cefuroxime, rifampicin, ciprofloxacin and amoxicillin/clavulanate. In group 3, to levofloxacin 93%, ciprofloxacin 89%, tobramycin 76%, but ceftazidime 53% and cefuroxime 29% decreased. None of the tested antibiotics could eradicate all possible conjunctival bacteria. Bacteria living permanently on the conjunctiva (group 1) have achieved higher resistance than the eventual colonizers. Copyright © 2013 Sociedad Española de Oftalmología. Published by Elsevier Espana. All rights reserved.

RNases and Helicases in Gram-Positive Bacteria.

Science.gov (United States)

Durand, Sylvain; Condon, Ciaran

2018-04-01

RNases are key enzymes involved in RNA maturation and degradation. Although they play a crucial role in all domains of life, bacteria, archaea, and eukaryotes have evolved with their own sets of RNases and proteins modulating their activities. In bacteria, these enzymes allow modulation of gene expression to adapt to rapidly changing environments. Today, >20 RNases have been identified in both Escherichia coli and Bacillus subtilis , the paradigms of the Gram-negative and Gram-positive bacteria, respectively. However, only a handful of these enzymes are common to these two organisms and some of them are essential to only one. Moreover, although sets of RNases can be very similar in closely related bacteria such as the Firmicutes Staphylococcus aureus and B. subtilis , the relative importance of individual enzymes in posttranscriptional regulation in these organisms varies. In this review, we detail the role of the main RNases involved in RNA maturation and degradation in Gram-positive bacteria, with an emphasis on the roles of RNase J1, RNase III, and RNase Y. We also discuss how other proteins such as helicases can modulate the RNA-degradation activities of these enzymes.

Using Bacteria to Store Renewable Energy (Text Version) | News | NREL

Science.gov (United States)

Using Bacteria to Store Renewable Energy (Text Version) Using Bacteria to Store Renewable Energy is a text version of the video entitled "Using Bacteria to Store Renewable Energy." ; Bacteria from some of the Earth's harshest environments now have a new home at NREL. [A natural spring has

Electron microscopic examination of uncultured soil-dwelling bacteria.

Science.gov (United States)

Amako, Kazunobu; Takade, Akemi; Taniai, Hiroaki; Yoshida, Shin-ichi

2008-05-01

Bacteria living in soil collected from a rice paddy in Fukuoka, Japan, were examined by electron microscopy using a freeze-substitution fixation method. Most of the observed bacteria could be categorized, based on the structure of the cell envelope and overall morphology, into one of five groups: (i) bacterial spore; (ii) Gram-positive type; (iii) Gram-negative type; (iv) Mycobacterium like; and (v) Archaea like. However, a few of the bacteria could not be readily categorized into one of these groups because they had unique cell wall structures, basically resembling those of Gram-negative bacteria, but with the layer corresponding to the peptidoglycan layer in Gram-negative bacteria being extremely thick, like that of the cortex of a bacterial spore. The characteristic morphological features found in many of these uncultured, soil-dwelling cells were the nucleoid being in a condensed state and the cytoplasm being shrunken. We were able to produce similar morphologies in vitro using a Salmonella sp. by culturing under low-temperature, low-nutrient conditions, similar to those found in some natural environments. These unusual morphologies are therefore hypothesized to be characteristic of bacteria in resting or dormant stages.

Roseobacter-clade bacteria as probiotics in marine larvaeculture

DEFF Research Database (Denmark)

Grotkjær, Torben

Disease caused by fish pathogenic bacteria can cause large scale crashes in marine fish larval rearing units. One of the biggest challenges for aquaculture is the management of these bacterial outbreaks. Vaccines can be admitted to fish but only the juvenile and the adult fish because they need...... to have a mature immune system. This means that the larvae of the fish, until they are 2-3 weeks old are more prone to bacterial infections. A short term solution is antibiotics but this leaves way for the selection for antibiotic resistance among the pathogenic bacteria, which again can be transferred...... to human pathogens. Alternatives are therefore needed and one could be the use of probiotic bacteria. Marine bacteria from the Roseobacter clade (Phaeobacter inhibens) have shown great potential as probiotic bacteria, and we have hypothesized that they could be used to antagonize pathogenic fish...

AZF Microdeletions in Human Semen Infected with Bacteria

Directory of Open Access Journals (Sweden)

Hayfa H Hassani

2011-11-01

Full Text Available Bacterial infections are associated with infertility in men. This study was aimed to investigate microdeletions on Yq chromosome in semen infected with bacteria by using bacteriological, biochemical, and serological assays. The investigation showed that 107 of 300 (84.80% semen samples collected from infertile men with primary or secondary infertility were infected with different species of bacteria. Chlamydia trachomatis and Neisseria gonorrheae were the most frequently diagnosed bacteria in the infected semen samples. The percentages of infections of semen samples with C. trachomatis and N. gonorrhea were 42.31% and 35.28% respectively. Genomic DNA from each semen sample infected with predominant bacteria was analyzed for AZF deletions by using multiplex PCR. Different patterns of AZF microdeletions were obtained. It can be concluded that sexually transmitted bacteria may contribute in microdeletions of Yq chromosome by indirectly producing reactive oxygen species and causing gene defect in AZF regions.

New Insight on the Response of Bacteria to Fluoride

OpenAIRE

Breaker, R.R.

2012-01-01

Fluoride has been used for decades to prevent caries and it is well established that this anion can inhibit the growth of bacteria. However, the precise effects that fluoride has on bacteria and the mechanisms that bacteria use to overcome fluoride toxicity have largely remained unexplored. Recently, my laboratory reported the discovery of biological systems that bacteria use to sense fluoride and reduce fluoride toxicity. These sensors and their associated genes are very widespread in biolog...

Antagonistic activity of isolated lactic acid bacteria from Pliek U against gram-negative bacteria Escherichia coli ATCC 25922

Science.gov (United States)

Kiti, A. A.; Jamilah, I.; Rusmarilin, H.

2017-09-01

Lactic acid bacteria (LAB) is one group of microbes that has many benefits, notably in food and health industries sector. LAB plays an important role in food fermentation and it has bacteriostatic effect against the growth of pathogenic microorganisms. The research related LAB continued to be done to increase the diversity of potential isolates derived from nature which is indigenous bacteria for biotechnological purposes. This study was aimed to isolate and characterize LAB derived from pliek u sample and to examine the potency to inhibits Escherichia coli ATCC 25922 bacteria growth. A total of 5 isolates were isolated and based on morphological and physiological characteristics of the fifth bacteria, they are allegedly belonging to the genus Bacillus. Result of antagonistic test showed that the five isolates could inhibits the growth of E. coli ATCC 25922. The highest inhibition zone is 8.5 mm was shown by isolates NQ2, while the lowest inhibition is 1.5 mm was shown by isolates NQ3.

Methylotrophic bacteria in sustainable agriculture.

Science.gov (United States)

Kumar, Manish; Tomar, Rajesh Singh; Lade, Harshad; Paul, Diby

2016-07-01

Excessive use of chemical fertilizers to increase production from available land has resulted in deterioration of soil quality. To prevent further soil deterioration, the use of methylotrophic bacteria that have the ability to colonize different habitats, including soil, sediment, water, and both epiphytes and endophytes as host plants, has been suggested for sustainable agriculture. Methylotrophic bacteria are known to play a significant role in the biogeochemical cycle in soil ecosystems, ultimately fortifying plants and sustaining agriculture. Methylotrophs also improve air quality by using volatile organic compounds such as dichloromethane, formaldehyde, methanol, and formic acid. Additionally, methylotrophs are involved in phosphorous, nitrogen, and carbon cycling and can help reduce global warming. In this review, different aspects of the interaction between methylotrophs and host plants are discussed, including the role of methylotrophs in phosphorus acquisition, nitrogen fixation, phytohormone production, iron chelation, and plant growth promotion, and co-inoculation of these bacteria as biofertilizers for viable agriculture practices.

Monitoring of airborne bacteria and aerosols in different wards of hospitals - Particle counting usefulness in investigation of airborne bacteria.

Science.gov (United States)

Mirhoseini, Seyed Hamed; Nikaeen, Mahnaz; Khanahmd, Hossein; Hatamzadeh, Maryam; Hassanzadeh, Akbar

2015-01-01

The presence of airborne bacteria in hospital environments is of great concern because of their potential role as a source of hospital-acquired infections (HAI). The aim of this study was the determination and comparison of the concentration of airborne bacteria in different wards of four educational hospitals, and evaluation of whether particle counting could be predictive of airborne bacterial concentration in different wards of a hospital. The study was performed in an operating theatre (OT), intensive care unit (ICU), surgery ward (SW) and internal medicine (IM) ward of four educational hospitals in Isfahan, Iran. A total of 80 samples were analyzed for the presence of airborne bacteria and particle levels. The average level of bacteria ranged from 75-1194 CFU/m (3) . Mean particle levels were higher than class 100,000 cleanrooms in all wards. A significant correlation was observed between the numbers of 1-5 µm particles and levels of airborne bacteria in operating theatres and ICUs. The results showed that factors which may influence the airborne bacterial level in hospital environments should be properly managed to minimize the risk of HAIs especially in operating theaters. Microbial air contamination of hospital settings should be performed by the monitoring of airborne bacteria, but particle counting could be considered as a good operative method for the continuous monitoring of air quality in operating theaters and ICUs where higher risks of infection are suspected.

Transmission of nephridial bacteria of the earthworm Eisenia fetida.

Science.gov (United States)

Davidson, Seana K; Stahl, David A

2006-01-01

The lumbricid earthworms (annelid family Lumbricidae) harbor gram-negative bacteria in their excretory organs, the nephridia. Comparative 16S rRNA gene sequencing of bacteria associated with the nephridia of several earthworm species has shown that each species of worm harbors a distinct bacterial species and that the bacteria from different species form a monophyletic cluster within the genus Acidovorax, suggesting that there is a specific association resulting from radiation from a common bacterial ancestor. Previous microscopy and culture studies revealed the presence of bacteria within the egg capsules and on the surface of embryos but did not demonstrate that the bacteria within the egg capsule were the same bacteria that colonized the nephridia. We present evidence, based on curing experiments, in situ hybridizations with Acidovorax-specific probes, and 16S rRNA gene sequence analysis, that the egg capsules contain high numbers of the bacterial symbiont and that juveniles are colonized during development within the egg capsule. Studies exposing aposymbiotic hatchlings to colonized adults and their bedding material suggested that juvenile earthworms do not readily acquire bacteria from the soil after hatching but must be colonized during development by bacteria deposited in the egg capsule. Whether this is due to the developmental stage of the host or the physiological state of the symbiont remains to be investigated.

Effect of radiation on activity of sulphate reducing bacteria

International Nuclear Information System (INIS)

Agaev, N.M.; Smorodin, A.E.; Gusejnov, M.M.

1985-01-01

The effect of γ-radiation on activity of sulphate reducing bacteria has been studied. Concentration of biogenic hydrogen, generated in the medium, is the main criterion, characterizing corrosion activity of the bacteria studied. The developed method of suppression of active development of sulfate reducing bacteria considerably reduces, and at lethal doses of γ-radiation eliminates altogether the bacteria activity and formation of the main corrosion agent-hydrogen sulphide-in the medium and that, in its turn, liquidates hydrogen sulphide corrosion

Methods and Techniques of Sampling, Culturing and Identifying of Subsurface Bacteria

International Nuclear Information System (INIS)

Lee, Seung Yeop; Baik, Min Hoon

2010-11-01

This report described sampling, culturing and identifying of KURT underground bacteria, which existed as iron-, manganese-, and sulfate-reducing bacteria. The methods of culturing and media preparation were different by bacteria species affecting bacteria growth-rates. It will be possible for the cultured bacteria to be used for various applied experiments and researches in the future

Encapsulation of bacteria and viruses in electrospun nanofibres

International Nuclear Information System (INIS)

Salalha, W; Kuhn, J; Dror, Y; Zussman, E

2006-01-01

Bacteria and viruses were encapsulated in electrospun polymer nanofibres. The bacteria and viruses were suspended in a solution of poly(vinyl alcohol) (PVA) in water and subjected to an electrostatic field of the order of 1 kV cm -1 . Encapsulated bacteria in this work (Escherichia coli, Staphylococcus albus) and bacterial viruses (T7, T4, λ) managed to survive the electrospinning process while maintaining their viability at fairly high levels. Subsequently the bacteria and viruses remain viable during three months at -20 and -55 deg. C without a further decrease in number. The present results demonstrate the potential of the electrospinning process for the encapsulation and immobilization of living biological material

Why bacteria matter in animal development and evolution.

Science.gov (United States)

Fraune, Sebastian; Bosch, Thomas C G

2010-07-01

While largely studied because of their harmful effects on human health, there is growing appreciation that bacteria are important partners for invertebrates and vertebrates, including man. Epithelia in metazoans do not only select their microbiota; a coevolved consortium of microbes enables both invertebrates and vertebrates to expand the range of diet supply, to shape the complex immune system and to control pathogenic bacteria. Microbes in zebrafish and mice regulate gut epithelial homeostasis. In a squid, microbes control the development of the symbiotic light organ. These discoveries point to a key role for bacteria in any metazoan existence, and imply that beneficial bacteria-host interactions should be considered an integral part of development and evolution.

Quantification and Qualification of Bacteria Trapped in Chewed Gum

NARCIS (Netherlands)

Wessel, Stefan W.; van der Mei, Henny C.; Morando, David; Slomp, Anje M.; van de Belt-Gritter, Betsy; Maitra, Amarnath; Busscher, Henk J.

2015-01-01

Chewing of gum contributes to the maintenance of oral health. Many oral diseases, including caries and periodontal disease, are caused by bacteria. However, it is unknown whether chewing of gum can remove bacteria from the oral cavity. Here, we hypothesize that chewing of gum can trap bacteria and

Bacteria associated with contamination of ready-to-eat (RTE ...

African Journals Online (AJOL)

The bacteria associated with contamination of ready-to-eat (RTE) cooked rice in Lagos, Nigeria were studied using standard microbiological methods. The objective of this study was to investigate the distribution of pathogenic bacteria recovered from RTE cooked rice in Lagos, assess bacteria load in the contaminated RTE ...

3D printing of bacteria into functional complex materials.

Science.gov (United States)

Schaffner, Manuel; Rühs, Patrick A; Coulter, Fergal; Kilcher, Samuel; Studart, André R

2017-12-01

Despite recent advances to control the spatial composition and dynamic functionalities of bacteria embedded in materials, bacterial localization into complex three-dimensional (3D) geometries remains a major challenge. We demonstrate a 3D printing approach to create bacteria-derived functional materials by combining the natural diverse metabolism of bacteria with the shape design freedom of additive manufacturing. To achieve this, we embedded bacteria in a biocompatible and functionalized 3D printing ink and printed two types of "living materials" capable of degrading pollutants and of producing medically relevant bacterial cellulose. With this versatile bacteria-printing platform, complex materials displaying spatially specific compositions, geometry, and properties not accessed by standard technologies can be assembled from bottom up for new biotechnological and biomedical applications.

[Teichoic acids from lactic acid bacteria].

Science.gov (United States)

Livins'ka, O P; Harmasheva, I L; Kovalenko, N K

2012-01-01

The current view of the structural diversity of teichoic acids and their involvement in the biological activity of lactobacilli has been reviewed. The mechanisms of effects of probiotic lactic acid bacteria, in particular adhesive and immunostimulating functions have been described. The prospects of the use of structure data of teichoic acid in the assessment of intraspecific diversity of lactic acid bacteria have been also reflected.

Use of thermophilic bacteria for bioremediation of petroleum contaminants

International Nuclear Information System (INIS)

Al-Maghrabi, I.M.A.; Bin Aqil, A.O.; Chaalal, O.; Islam, M.R.

1999-01-01

Several strains of thermophilic bacteria were isolated from the environment of the United Arab Emirates. These bacteria show extraordinary resistance to heat and have their maximum growth rate around 60--80 C. This article investigates the potential of using these facultative bacteria for both in situ and ex situ bioremediation of petroleum contaminants. In a series of batch experiments, bacterial growth was observed using a computer image analyzer following a recently developed technique. These experiments showed clearly that the growth rate is enhanced in the presence of crude oil. This is coupled with a rapid degradation of the crude oil. These bacteria were found to be ideal for breaking down long-chain organic molecules at a temperature of 40 C, which is the typical ambient temperature of the Persian Gulf region. The same strains of bacteria are also capable of surviving in the presence of the saline environment that can prevail in both sea water and reservoir connate water. This observation prompted further investigation into the applicability of the bacteria in microbial enhanced oil recovery. In the United Arab Emirates, the reservoirs are typically at a temperature of around 85 C. Finally, the performance of the bacteria is tested in a newly developed bioreactor that uses continuous aeration through a transverse slotted pipe. This reactor also uses mixing without damaging the filamentous bacteria. In this process, the mechanisms of bioremediation are identified

The aerobic activity of metronidazole against anaerobic bacteria.

Science.gov (United States)

Dione, Niokhor; Khelaifia, Saber; Lagier, Jean-Christophe; Raoult, Didier

2015-05-01

Recently, the aerobic growth of strictly anaerobic bacteria was demonstrated using antioxidants. Metronidazole is frequently used to treat infections caused by anaerobic bacteria; however, to date its antibacterial activity was only tested in anaerobic conditions. Here we aerobically tested using antioxidants the in vitro activities of metronidazole, gentamicin, doxycycline and imipenem against 10 common anaerobic and aerobic bacteria. In vitro susceptibility testing was performed by the disk diffusion method, and minimum inhibitory concentrations (MICs) were determined by Etest. Aerobic culture of the bacteria was performed at 37°C using Schaedler agar medium supplemented with 1mg/mL ascorbic acid and 0.1mg/mL glutathione; the pH was adjusted to 7.2 by 10M KOH. Growth of anaerobic bacteria cultured aerobically using antioxidants was inhibited by metronidazole after 72h of incubation at 37°C, with a mean inhibition diameter of 37.76mm and an MIC of 1μg/mL; however, strains remained non-sensitive to gentamicin. No growth inhibition of aerobic bacteria was observed after 24h of incubation at 37°C with metronidazole; however, inhibition was observed with doxycycline and imipenem used as controls. These results indicate that bacterial sensitivity to metronidazole is not related to the oxygen tension but is a result of the sensitivity of the micro-organism. In future, both culture and antibiotic susceptibility testing of strictly anaerobic bacteria will be performed in an aerobic atmosphere using antioxidants in clinical microbiology laboratories. Copyright © 2015 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

Effects of ionizing radiation on bacteria

Energy Technology Data Exchange (ETDEWEB)

Suhadi, F [National Atomic Energy Agency, Jakarta (Indonesia). Pasar Djumat Research Centre

1976-10-01

The differences of radiosensitivities among bacteria in addition to the dependence upon the species or strains also depends on the environmental condition during irradiation (temperature, medium, the presence of protective or sensitizing agents, the gas phase or atmosphere, and water activity, or degree of hydration) and on the effects of the environmental condition before and after irradiation treatment (temperature of incubation, age of culture and growth medium). In general, spores are more resistant to radiation than vegetatic bacteria, with the exception that a few cocci are the most radiation resistant bacteria (Micrococcus and Streptococcus). The application of ionizing radiation in the fields of microbiology supports the radiation sterilization of medical and pharmaceutical products. In addition, microbiological aspects of food preservation, especially radurization, radicidation, and immunization studies by using irradiated microorganisms, are also important.

Lethal photosensitization of biofilm-grown bacteria

Science.gov (United States)

Wilson, Michael

1997-12-01

Antibacterial agents are increasingly being used for the prophylaxis and treatment of oral diseases. As these agents can be rendered ineffective by resistance development in the target organisms there is a need to develop alternative antimicrobial approaches. Light-activated antimicrobial agents release singlet oxygen and free radicals which can kill adjacent bacteria and a wide range of cariogenic and periodontopathogenic bacteria has been shown to be susceptible to such agents. In the oral cavity these organisms are present as biofilms (dental plaques) which are less susceptible to traditional antimicrobial agents than bacterial suspensions. The results of these studies have shown that biofilm-grown oral bacteria are also susceptible to lethal photosensitization although the light energy doses required are grater than those needed to kill the organisms when they are grown as aqueous suspensions.

Analyzing Arthropods for the Presence of Bacteria

OpenAIRE

Andrews, Elizabeth S.

2013-01-01

Bacteria within arthropods can be identified using culture-independent methods. This unit describes protocols for surface sterilization of arthropods, DNA extraction of whole bodies and tissues, touchdown PCR amplification using 16S rDNA general bacteria primers and profiling the bacterial community using denaturing gradient gel electrophoresis.

Isolation and characterization of autotrophic, hydrogen-utilizing, perchlorate-reducing bacteria.

Science.gov (United States)

Shrout, Joshua D; Scheetz, Todd E; Casavant, Thomas L; Parkin, Gene F

2005-04-01

Recent studies have shown that perchlorate (ClO(4) (-)) can be degraded by some pure-culture and mixed-culture bacteria with the addition of hydrogen. This paper describes the isolation of two hydrogen-utilizing perchlorate-degrading bacteria capable of using inorganic carbon for growth. These autotrophic bacteria are within the genus Dechloromonas and are the first Dechloromonas species that are microaerophilic and incapable of growth at atmospheric oxygen concentrations. Dechloromonas sp. JDS5 and Dechloromonas sp. JDS6 are the first perchlorate-degrading autotrophs isolated from a perchlorate-contaminated site. Measured hydrogen thresholds were higher than for other environmentally significant, hydrogen-utilizing, anaerobic bacteria (e.g., halorespirers). The chlorite dismutase activity of these bacteria was greater for autotrophically grown cells than for cells grown heterotrophically on lactate. These bacteria used fumarate as an alternate electron acceptor, which is the first report of growth on an organic electron acceptor by perchlorate-reducing bacteria.

Antibiotic-producing bacteria from stag beetle mycangia.

Science.gov (United States)

Miyashita, Atsushi; Hirai, Yuuki; Sekimizu, Kazuhisa; Kaito, Chikara

2015-02-01

The search for new antibiotics or antifungal agents is crucial for the chemotherapies of infectious diseases. The limited resource of soil bacteria makes it difficult to discover such new drug candidate. We, therefore, focused on another bacterial resource than soil bacteria, the microbial flora of insect species. In the present study, we isolated 40 strains of bacteria and fungi from the mycangia of three species of stag beetle, Dorcus hopei binodulosus, Dorcus rectus, and Dorcus titanus pilifer. We identified those species with their ribosomal DNA sequences, and revealed that Klebsiella spp. are the most frequent symbiont in the stag beetle mycangia. We examined whether these microorganisms produce antibiotics against a Gram-negative bacterium, Escherichia coli, a Gram-positive bacterium, Staphylococcus aureus, or a fungus, Cryptococcus neoformans. Culture supernatants from 33, 29, or 18 strains showed antimicrobial activity against E. coli, S. aureus, or C. neoformans, respectively. These findings suggest that bacteria present in the mycangia of stag beetles are useful resources for screening novel antibiotics.

Bile anaerobic bacteria detection and antibiotic susceptibility in patients with gallstone.

Science.gov (United States)

Lu, Yun; Xiang, Ting-Hai; Shi, Jing-Sen; Zhang, Bing-Yuan

2003-08-01

To detect bile anaerobic bacteria and antibiotic susceptibility in 59 patients with gallstones who had had cholecystectomy. BACT/ALERT 120 microbe detection system and SCEPTOR microbe detection system were used to detect bile anaerobic bacteria, antibiotic susceptibility. The ratio of anaerobic bacteria to the patients examined was 52.5% (31/59). Obligate anaerobe bile culture showed positive results in 4 patients. B. fragilis (37.8%) was the major type of anaerobic bacteria in bile. Most (81.8%) of anaerobic bacteria were sensitive to metronidazole, and imipenem was suitable for beta-lactamase bacteria. Culture of anaerobic bacteria in logarithmic phase can improve the positive rate of the culture. There are some relations between anaerobic infection and gallstone formation.

Screening identification of aerobic denitrification bacteria with high soil desalinization capacity

Science.gov (United States)

Jin, H.; Chen, H.; Jin, H.; Qian, Y.; Zhang, K.

2017-08-01

In order to study the mechanism of bacteria used in the saline soil remediation process, the aerobic denitrification bacteria were isolated from an agricultural greenhouse soil in a farm in East China’s Zhejiang Province. The identification, nitrogen reducing characteristics and the denitrification effect of bacteria from different soils at various locations were investigated. The results showed that the NO3- removal rate was 91% with bacteria from the greenhouse soil under aerobic conditions in 52 h, and the bacteria were identified as Gram-positive Castellaniella denitrification bacteria.

Working with bacteria and putting bacteria to work: The biopolitics of synthetic biology for energy in the United Kingdom.

Science.gov (United States)

McLeod, Carmen; Nerlich, Brigitte; Mohr, Alison

2017-08-01

The UK government has made significant investment into so called 'fourth-generation' biofuel technologies. These biofuels are based on engineering the metabolic pathways of bacteria in order to create products compatible with existing infrastructure. Bacteria play an important role in what is promoted as a potentially new biological industrial revolution, which could address some of the negative environmental legacies of the last. This article presents results from ethnographic research with synthetic biologists who are challenged with balancing the curiosity-driven and intrinsically fulfilling scientific task of working with bacteria, alongside the policy-driven task of putting bacteria to work for extrinsic economic gains. In addition, the scientists also have to balance these demands with a new research governance framework, Responsible Research and Innovation, which envisions technoscientific innovation will be responsive to societal concerns and work in collaboration with stakeholders and members of the public. Major themes emerging from the ethnographic research revolve around stewardship, care, responsibility and agency. An overall conflict surfaces between individual agents assuming responsibility for 'stewarding' bacteria, against funding systems and structures imposing responsibility for economic growth. We discuss these findings against the theoretical backdrop of a new concept of 'energopolitics' and an anthropology of ethics and responsibility.

DEVELOPMENT OF TOFU PRODUCTION METHOD WITH PROBIOTIC BACTERIA ADDITION

Directory of Open Access Journals (Sweden)

Dorota Zielińska

2015-06-01

Full Text Available The aim of the study was to develop a production method for tofu with probiotic bacteria under laboratory conditions. The works included: selection of a strain and tofu production conditions, and a storage test of the manufactured product. It was concluded that the sensory quality of tofu with the addition of different probiotic cultures did not differ significantly (p>0.01, depending on used strains and their mixtures, and the sample quality was comparable to the commercial product. It was observed that the number of Lactobacillus bacteria in study samples was the factor determining the palatability of tofu (r= 0.75. On the other hand, the sensory quality of products was significantly affected by the production method of tofu with the addition of probiotic bacteria. It was concluded that the formation of curds from soy beverage by the addition of CaSO4, followed by inoculation with Lactobacillus casei ŁOCK 0900 at the amount of 9.26 log CFU/g and incubation at temp. of 37C for 2h as well as for 20h are methods recommended for production tofu with regard to sensory qualities of the final product among all tested methods. The number of lactic acid bacteria in studied tofu samples was maintained at the high level (109-1010 CFU/g, and the number of Bifidobacterium animalis ssp lactis BB-12 bacteria did not exceed 103 CFU/g, whereas the number of Lactobacillus bacteria was equal to 108-109 CFU/g. For the period of 15 days of storage of tofu with probiotic bacteria at the temperature of 4C the number of lactic acid bacteria was maintained at the constant level of approx. 109 CFU/g. It was concluded that it is possible to produce tofu with probiotic bacteria that has acceptable sensory characteristics and a high number of lactic acid bacteria, therefore the product could be considered as a functional one.

Antioxidant and Antimicrobial Potential of the Bifurcaria bifurcata Epiphytic Bacteria

Directory of Open Access Journals (Sweden)

André Horta

2014-03-01

Full Text Available Surface-associated marine bacteria are an interesting source of new secondary metabolites. The aim of this study was the isolation and identification of epiphytic bacteria from the marine brown alga, Bifurcaria bifurcata, and the evaluation of the antioxidant and antimicrobial activity of bacteria extracts. The identification of epiphytic bacteria was determined by 16S rRNA gene sequencing. Bacteria extracts were obtained with methanol and dichloromethane (1:1 extraction. The antioxidant activity of extracts was performed by quantification of total phenolic content (TPC, 2,2-diphenyl-1-picrylhydrazyl (DPPH radical scavenging activity and oxygen radical absorbance capacity (ORAC. Antimicrobial activities were evaluated against Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, Salmonella enteritidis, Staphylococcus aureus, Saccharomyces cerevisiae and Candida albicans. A total of 39 Bifurcaria bifurcata-associated bacteria were isolated and 33 were identified as Vibrio sp. (48.72%, Alteromonas sp. (12.82%, Shewanella sp. (12.26%, Serratia sp. (2.56%, Citricoccus sp. (2.56%, Cellulophaga sp. (2.56%, Ruegeria sp. (2.56% and Staphylococcus sp. (2.56%. Six (15.38% of the 39 bacteria Bifurcaria bifurcata-associated bacteria presented less than a 90% Basic Local Alignment Search Tool (BLAST match, and some of those could be new. The highest antioxidant activity and antimicrobial activity (against B. subtilis was exhibited by strain 16 (Shewanella sp.. Several strains also presented high antimicrobial activity against S. aureus, mainly belonging to Alteromonas sp. and Vibrio sp. There were no positive results against fungi and Gram-negative bacteria. Bifurcaria bifurcata epiphytic bacteria were revealed to be excellent sources of natural antioxidant and antimicrobial compounds.

Antioxidant and antimicrobial potential of the Bifurcaria bifurcata epiphytic bacteria.

Science.gov (United States)

Horta, André; Pinteus, Susete; Alves, Celso; Fino, Nádia; Silva, Joana; Fernandez, Sara; Rodrigues, Américo; Pedrosa, Rui

2014-03-24

Surface-associated marine bacteria are an interesting source of new secondary metabolites. The aim of this study was the isolation and identification of epiphytic bacteria from the marine brown alga, Bifurcaria bifurcata, and the evaluation of the antioxidant and antimicrobial activity of bacteria extracts. The identification of epiphytic bacteria was determined by 16S rRNA gene sequencing. Bacteria extracts were obtained with methanol and dichloromethane (1:1) extraction. The antioxidant activity of extracts was performed by quantification of total phenolic content (TPC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and oxygen radical absorbance capacity (ORAC). Antimicrobial activities were evaluated against Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, Salmonella enteritidis, Staphylococcus aureus, Saccharomyces cerevisiae and Candida albicans. A total of 39 Bifurcaria bifurcata-associated bacteria were isolated and 33 were identified as Vibrio sp. (48.72%), Alteromonas sp. (12.82%), Shewanella sp. (12.26%), Serratia sp. (2.56%), Citricoccus sp. (2.56%), Cellulophaga sp. (2.56%), Ruegeria sp. (2.56%) and Staphylococcus sp. (2.56%). Six (15.38%) of the 39 bacteria Bifurcaria bifurcata-associated bacteria presented less than a 90% Basic Local Alignment Search Tool (BLAST) match, and some of those could be new. The highest antioxidant activity and antimicrobial activity (against B. subtilis) was exhibited by strain 16 (Shewanella sp.). Several strains also presented high antimicrobial activity against S. aureus, mainly belonging to Alteromonas sp. and Vibrio sp. There were no positive results against fungi and Gram-negative bacteria. Bifurcaria bifurcata epiphytic bacteria were revealed to be excellent sources of natural antioxidant and antimicrobial compounds.

A porous silicon optical microcavity for sensitive bacteria detection

International Nuclear Information System (INIS)

Li Sha; Huang Jianfeng; Cai Lintao

2011-01-01

A porous silicon microcavity (PSM) is highly sensitive to subtle interface changes due to its high surface area, capillary condensation ability and a narrow resonance peak (∼10 nm). Based on the well-defined optical properties of a PSM, we successfully fabricated a bacteria detection chip for molecular or subcellular analysis by surface modification using undecylenic acid (UA), and the specific recognition binding of vancomycin to the D-alanyl-D-alanine of bacteria. The red shift of the PSM resonance peak showed a good linear relationship with bacteria concentration ranging from 100 to 1000 bacteria ml -1 at the level of relative standard deviation of 0.994 and detection limit of 20 bacteria ml -1 . The resulting PSM sensors demonstrated high sensitivity, good reproducibility, fast response and low cost for biosensing.

A porous silicon optical microcavity for sensitive bacteria detection

Science.gov (United States)

Li, Sha; Huang, Jianfeng; Cai, Lintao

2011-10-01

A porous silicon microcavity (PSM) is highly sensitive to subtle interface changes due to its high surface area, capillary condensation ability and a narrow resonance peak (~10 nm). Based on the well-defined optical properties of a PSM, we successfully fabricated a bacteria detection chip for molecular or subcellular analysis by surface modification using undecylenic acid (UA), and the specific recognition binding of vancomycin to the D-alanyl-D-alanine of bacteria. The red shift of the PSM resonance peak showed a good linear relationship with bacteria concentration ranging from 100 to 1000 bacteria ml - 1 at the level of relative standard deviation of 0.994 and detection limit of 20 bacteria ml - 1. The resulting PSM sensors demonstrated high sensitivity, good reproducibility, fast response and low cost for biosensing.

A porous silicon optical microcavity for sensitive bacteria detection

Energy Technology Data Exchange (ETDEWEB)

Li Sha; Huang Jianfeng; Cai Lintao, E-mail: lt.cai@siat.ac.cn [CAS Key Lab of Health Informatics, Shenzhen Key Laboratory of Cancer Nanotechnology, Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055 (China)

2011-10-21

A porous silicon microcavity (PSM) is highly sensitive to subtle interface changes due to its high surface area, capillary condensation ability and a narrow resonance peak ({approx}10 nm). Based on the well-defined optical properties of a PSM, we successfully fabricated a bacteria detection chip for molecular or subcellular analysis by surface modification using undecylenic acid (UA), and the specific recognition binding of vancomycin to the D-alanyl-D-alanine of bacteria. The red shift of the PSM resonance peak showed a good linear relationship with bacteria concentration ranging from 100 to 1000 bacteria ml{sup -1} at the level of relative standard deviation of 0.994 and detection limit of 20 bacteria ml{sup -1}. The resulting PSM sensors demonstrated high sensitivity, good reproducibility, fast response and low cost for biosensing.

Physiological and genetics studies of highly radiation-resistant bacteria

International Nuclear Information System (INIS)

Keller, L.C.

1981-01-01

The phenomenon of radiation resistance was studied using micrococci and Moraxella-Acinetobacter capable of surviving very high doses of gamma radiation which were isolated from foods. Physiological age, or growth phase, was found to be an important factor in making comparisons of radiation-resistance among different bacteria and their mutants. Radiation-resistant bacteria were highly resistant to the lethal effect of nitrosoguanidine used for mutagenesis. Studies of relative resistance of radiation-resistant bacteria, radiation-sensitive mutants, and nonradiation-resistant bacteria to killing by different chemical mutagens did not reveal a correlation between the traits of radiation resistance and mutagen resistance among different strains. Comparisons of plasmid profiles of radiation-resistant bacteria and selected radiation-sensitive mutants suggested the possibility that plasmids may carry genes involved in radiation resistance

Stalking Antibiotic-Resistant Bacteria in Common Vegetables

Science.gov (United States)

Brock, David; Boeke, Caroline; Josowitz, Rebecca; Loya, Katherine

2004-01-01

The study developed a simple experimental protocol for studying antibiotic resistant bacteria that will allow students to determine the proportion of such bacteria found on common fruit and vegetable crops. This protocol can open up the world of environmental science and show how human behavior can dramatically alter ecosystems.

Effect of ionizing radiation on the antigenic composition of typhoid bacteria

International Nuclear Information System (INIS)

Sinilova, N.G.; Nikolaeva, L.A.; Tumanyan, M.A.

1978-01-01

Changes in the antigenic composition of typhoid bacteria occurring during the exposure of microbial suspension to different doses of gamma radiation ( 60 Co) ranging between 0.5 and 3.0 Mrad were studied. Immunoelectrophoresis in agar was used to determine the antigenic composition of different samples of irradiated bacteria. The antigenic composition of bacteria irradiated with doses up to 2.5 Mrad was found to be similar to that of non-irradiated bacteria. Antigens demonstrated by means of Vi, H and O antisera are preserved in these bacteria. However, all irradiated bacteria in general slightly differ from non-irradiated bacteria; this is manifest in a different configuration and position of the precipitation lines in the cathodic part of the immunophoreograms. The content of the component migrating rapidly towards the cathode, evidently the O antigen in the R form, in the irradiated bacteria increases with the dose of radiation. No new serologically active substances, non-existent in non-irradiated bacteria, were found to appear in the process of irradiation. (author)

Reducing gas content of coal deposits by means of bacteria

Energy Technology Data Exchange (ETDEWEB)

Godlewska-Lipowa, A A; Kozlowski, B

1981-07-01

This paper discusses the results of experiments carried out in Poland under laboratory conditions on efficiency of methane control using bacteria from Methanosarcina and Methanomonas groups. Malashenko and Whittenburry culture mediums were used. Bacteria growth in an atmosphere of air and methane (48.2%, 8.6% and 5.21%) was observed. Temperature ranged from 19 to 20 C. Investigations show that the bacteria are characterized by high oxidation activity. Depending on methane concentration in the air the bacteria consume from 75% to 100% of methane during biosynthesis. The bacteria reduce methane and oxygen content and increase carbon dioxide content in the air. Using bacteria methane concentration in the air was reduced from 48.2% to 12.3%, from 8.6% to 0.0% and from 5.21% to 0.01%. (7 refs.) (In Polish)

Novel Adaptive Bacteria Foraging Algorithms for Global Optimization

Directory of Open Access Journals (Sweden)

Ahmad N. K. Nasir

2014-01-01

Full Text Available This paper presents improved versions of bacterial foraging algorithm (BFA. The chemotaxis feature of bacteria through random motion is an effective strategy for exploring the optimum point in a search area. The selection of small step size value in the bacteria motion leads to high accuracy in the solution but it offers slow convergence. On the contrary, defining a large step size in the motion provides faster convergence but the bacteria will be unable to locate the optimum point hence reducing the fitness accuracy. In order to overcome such problems, novel linear and nonlinear mathematical relationships based on the index of iteration, index of bacteria, and fitness cost are adopted which can dynamically vary the step size of bacteria movement. The proposed algorithms are tested with several unimodal and multimodal benchmark functions in comparison with the original BFA. Moreover, the application of the proposed algorithms in modelling of a twin rotor system is presented. The results show that the proposed algorithms outperform the predecessor algorithm in all test functions and acquire better model for the twin rotor system.

[Effects of transgenic Bt + CpTI cotton on rhizosphere bacteria and ammonia oxidizing bacteria population].

Science.gov (United States)

Dong, Lianhua; Meng, Ying; Wang, Jing

2014-03-04

The effect of transgenic cotton on the rhizosphere bacteria can be important to the risk assessment for the genetically modified crops. We studied the rhizosphere microbial community with cultivating genetically modified cotton. The effects of transgenic Bt + CpTI Cotton (SGK321) and its receptor cotton (SY321) on rhizosphere total bacteria and ammonia oxidizing bacteria population size were studied by using droplet digital PCR. We collected rhizosphere soil before cotton planting and along with the cotton growth stage (squaring stage, flowering stage, belling stage and boll opening stage). There was no significant change on the total bacterial population between the transgenic cotton and the receptor cotton along with the growth stage. However, the abundance of ammonia oxidizing bacteria (AOB) in both type of cottons showed significant difference between different growth stages, and the variation tendency was different. In squaring stage, the numbers of AOB in rhizosphere of SY321 and SGK321 increased 4 and 2 times, respectively. In flowering stage, AOB number in rhizosphere of SY321 significantly decreased to be 5.96 x 10(5) copies/g dry soil, however, that of SGK321 increased to be 1.25 x 10(6) copies/g dry soil. In belling stage, AOB number of SY321 greatly increased to be 1.49 x 10(6) copies/g dry soil, but no significant change was observed for AOB number of SGK321. In boll opening stage, both AOB number of SY321 and SGK321 clearly decreased and they were significantly different from each other. Compared to the non-genetically modified cotton, the change in abundance of ammonia oxidizing bacteria was slightly smooth in the transgenic cotton. Not only the cotton growth stage but also the cotton type caused this difference. The transgenic cotton can slow down the speed of ammonia transformation through impacting the number of AOB, which is advantageous for plant growth.

Meeting on the Microbiology of Soils, Autumn 2001: Estimation of protozoan diversity in soil

DEFF Research Database (Denmark)

Ekelund, Flemming

2002-01-01

Different methods of estimating protozoan diversity in soil are discussed in this paper, with the major emphasis on heterotrophic flagellates. Although many species of ciliates and testate amoebae seem to be unique to the soil environment, the communities of heterotrophic flagellates and naked am...

Bactericidal effects of antibiotics on slowly growing and nongrowing bacteria.

OpenAIRE

Eng, R H; Padberg, F T; Smith, S M; Tan, E N; Cherubin, C E

1991-01-01

Antimicrobial agents are most often tested against bacteria in the log phase of multiplication to produce the maximum bactericidal effect. In an infection, bacteria may multiply less optimally. We examined the effects of several classes of antimicrobial agents to determine their actions on gram-positive and gram-negative bacteria during nongrowing and slowly growing phases. Only ciprofloxacin and ofloxacin exhibited bactericidal activity against nongrowing gram-negative bacteria, and no antib...

Bacteria Isolated from Post-Partum Infections

Directory of Open Access Journals (Sweden)

Nahid Arianpour

2009-06-01

Full Text Available Objective: This study was undertaken with an aim to determine bacterial species involved in post partum infections and also their abundance in patients admitted to at Khanevadeh hospital. In this study out of three different kinds of postpartum infections (i.e. genital, breast and urinary tract, only genital infection is considered.Materials and Methods: Post partum infection among 6077 patients (inpatients and re-admitted patients of Khanevadeh hospital from 2003 till 2008 was studied in this descriptive study. Samples were collected from patients for laboratory diagnosis to find out the causative organisms.Results: Follow up of mothers after delivery revealed 7.59% (461 patients had post partum infection, out of which 1.03% (63 patients were re-hospitalized. Infection was more often among younger mothers. Bacteria isolated and identified were both aerobic and anaerobic cocci and bacilli, majority of which were normal flora of the site of infection. Though, some pathogenic bacteria like Staphylococcus aureus, Neisseria gonorrhea, Chlamydia trachomatis,were also the causative agents. The commonest infection was infection at the site of episiotomy. Conclusion: Puerperal infection was detected in of 7.59% mothers. Bacteria isolated were both aerobic and anaerobic cocci and bacilli, majority of which were normal flora. However; some pathogenic bacteria were isolated.

Luminous bacteria cultured from fish guts in the Gulf of Oman.

Science.gov (United States)

Makemson, J C; Hermosa, G V

1999-01-01

The incidence of culturable luminous bacteria in Omani market fish guts was correlated to habitat type amongst 109 species of fish. Isolated representative luminous bacteria were compared to known species using the Biolog system (95 traits/isolate) and cluster analysis, which showed that the main taxa present in fish guts were clades related to Vibrio harveyi and Photobacterium species with sporadic incidence of P. phosphoreum. The luminous isolates from gut of the slip-mouth (barred pony fish), Leiognathus fasciatus, were mainly a type related to Photobacterium but phenotypically different from known species. These luminous gut bacteria were identical with the bacteria in the light organ, indicating that the light organ supplies a significant quantity of luminous bacteria to the gut. In many of the fish that lack light organs, luminous bacteria were also the dominant bacterial type in the gut, while in some others luminous bacteria were encountered sporadically and at low densities, reflecting the incidence of culturable luminous bacteria in seawater. Pelagic fish contained the highest incidence of culturable luminous bacteria and reef-associated fish the lowest. No correlation was found between the incidence of culturable luminous bacteria and the degree to which fish produce a melanin-covered gut. Copyright 1999 John Wiley & Sons, Ltd.

Investigation of IR absorption spectra of oral cavity bacteria

Science.gov (United States)

Belikov, Andrei V.; Altshuler, Gregory B.; Moroz, Boris T.; Pavlovskaya, Irina V.

1996-12-01

The results of comparative investigation for IR and visual absorption spectra of oral cavity bacteria are represented by this paper. There are also shown the main differences in absorption spectra of such pure bacteria cultures as : E- coli, Candida, Staph, Epidermidis, and absorption spectra of bacteria colonies cultured in tooth root canals suspected to harbour several endodontical problems. The results of experimental research targeted to investigate an effect of such combined YAG:Nd and YAG:Cr; Tm; Ho laser parameters like: wavelength, energy density, average power and etc., to oral cavity bacteria deactivation are given finally.

Oh What a Tangled Biofilm Web Bacteria Weave

Science.gov (United States)

... Home Page Oh What a Tangled Biofilm Web Bacteria Weave By Elia Ben-Ari Posted May 1, ... a suitable surface, some water and nutrients, and bacteria will likely put down stakes and form biofilms. ...

Toxicity of tetracyclines and tetracycline degradation products to environmentally relevant bacteria, including selected tetracycline-resistant bacteria

DEFF Research Database (Denmark)

Halling-Sørensen, B.; Sengeløv, G.; Tjørnelund, J.

2002-01-01

Tetracyclines used in veterinary therapy invariably will find their way as parent compound and degradation products to the agricultural field. Major degradation products formed due to the limited stability of parent tetracyclines (tetracycline, chlortetracycline, and oxytetracycline) in aqueous...... at the same concentration level as tetracycline, chlortetracycline, and oxytetracycline on both the sludge and the tetracycline-sensitive soil bacteria. Further, both 5a,6-anhydrotetracychne and 5a,6-anhydrochlortetracycline had potency on tetracycline-resistant bacteria supporting a mode of action different...

Anaerobic bacteria in the gut of terrestrial isopod Crustacean Porcellio scaber.

Science.gov (United States)

Kostanjsek, R; Lapanje, A; Rupnik, M; Strus, J; Drobne, D; Avgustin, G

2004-01-01

Anaerobic bacteria from Porcellio scaber hindgut were identified and, subsequently, isolated using molecular approach. Phylogenetic affiliation of bacteria associated with the hindgut wall was determined by analysis of bacterial 16S rRNA gene sequences which were retrieved directly from washed hindguts of P. scaber. Sequences from bacteria related to obligate anaerobic bacteria from genera Bacteroides and Enterococcus were retrieved, as well as sequences from 'A1 subcluster' of the wall-less mollicutes. Bacteria from the genus Desulfotomaculum were isolated from gut wall and cultivated under anaerobic conditions. In contrast to previous reports which suggested the absence of anaerobic bacteria in the isopod digestive system due to short retention time of the food in the tube-like hindgut, frequent renewal of the gut cuticle during the moulting process, and unsuccessful attempts to isolate anaerobic bacteria from this environment our results indicate the presence of resident anaerobic bacteria in the gut of P. scaber, in spite of apparently unsuitable, i.e. predominantly oxic, conditions.

Nitrogen acquisition in Agave tequilana from degradation of endophytic bacteria.

Science.gov (United States)

Beltran-Garcia, Miguel J; White, James F; Prado, Fernanda M; Prieto, Katia R; Yamaguchi, Lydia F; Torres, Monica S; Kato, Massuo J; Medeiros, Marisa H G; Di Mascio, Paolo

2014-11-06

Plants form symbiotic associations with endophytic bacteria within tissues of leaves, stems, and roots. It is unclear whether or how plants obtain nitrogen from these endophytic bacteria. Here we present evidence showing nitrogen flow from endophytic bacteria to plants in a process that appears to involve oxidative degradation of bacteria. In our experiments we employed Agave tequilana and its seed-transmitted endophyte Bacillus tequilensis to elucidate organic nitrogen transfer from (15)N-labeled bacteria to plants. Bacillus tequilensis cells grown in a minimal medium with (15)NH4Cl as the nitrogen source were watered onto plants growing in sand. We traced incorporation of (15)N into tryptophan, deoxynucleosides and pheophytin derived from chlorophyll a. Probes for hydrogen peroxide show its presence during degradation of bacteria in plant tissues, supporting involvement of reactive oxygen in the degradation process. In another experiment to assess nitrogen absorbed as a result of endophytic colonization of plants we demonstrated that endophytic bacteria potentially transfer more nitrogen to plants and stimulate greater biomass in plants than heat-killed bacteria that do not colonize plants but instead degrade in the soil. Findings presented here support the hypothesis that some plants under nutrient limitation may degrade and obtain nitrogen from endophytic microbes.

The effects of deuterium-depleted water on bacteria

International Nuclear Information System (INIS)

Butnaru, Gallia; Jurca, Elena M.; Titescu, Gh.; Stefanescu, I.

2000-01-01

Due to their adaptability the bacteria are ubiquitous, occurring in a large variety of habitats. Most of them are saprotrophs or parasites. Bacteria are agents causing many diseases in animals and humans. The main purpose of this work was to reveal the deuterium-depleted water bactericidal effect. Nonpathogenic Gram-positive (Bacillus subtilis and Bacillus cereus) and pathogenic Gram-negative (Agrobacterium tumefaciens, Erwinia amylovora and Escherichia coli) bacteria were used. The variant deuterium depleted (DDW) eater was compared with distilled water eater one. The diffusometric method was found the proper way of investigation. The bacteria culture was developed in Petri dishes (diam = 70 mm) at a temperature of 25 deg. C. After 24 h, 48 h and 72 h the clear area was measured. The clear area was one in which the bacteria were killed. The surface was determined by the area of the small disc on the filter paper. The statistical data were determined by variance analysis. The results pointed out a large response to DDW presence. The data were classified in: 1. without response when no clear area occurred; - 2. with response when a clear area of under 5 mm 2 occurred; - 3. strong response when the clear area was higher than 10 mm 2 . The Gram-positive and Gram-negative bacteria behaviours were not in correlation with the DDW bactericidal effect. The Bacillus cereus and Escherichia coli were scored as without response and we presume that they were very tolerant. No clear area was induced by DDW. Bacillus subtilis and Erwinia amylovora showed weak response. After 24 h the killed bacteria were extended on the same area, namely, 2.89 mm 2 . Even if the DDW effect seems to be small it was significantly in comparison with the control case (s d = 2.78 mm 2 > 0.1). After 48 h and 72 h the clear surface remained the same. The Agrobacterium tumefaciens' response was very strong. The bacteria were killed on 22.50 mm 2 after 24 h and on 26.95 mm 2 after 48 h, being very

Leucine incorporation by aerobic anoxygenic phototrophic bacteria in the Delaware estuary

Science.gov (United States)

Stegman, Monica R; Cottrell, Matthew T; Kirchman, David L

2014-01-01

Aerobic anoxygenic phototrophic (AAP) bacteria are well known to be abundant in estuaries, coastal regions and in the open ocean, but little is known about their activity in any aquatic ecosystem. To explore the activity of AAP bacteria in the Delaware estuary and coastal waters, single-cell 3H-leucine incorporation by these bacteria was examined with a new approach that combines infrared epifluorescence microscopy and microautoradiography. The approach was used on samples from the Delaware coast from August through December and on transects through the Delaware estuary in August and November 2011. The percent of active AAP bacteria was up to twofold higher than the percentage of active cells in the rest of the bacterial community in the estuary. Likewise, the silver grain area around active AAP bacteria in microautoradiography preparations was larger than the area around cells in the rest of the bacterial community, indicating higher rates of leucine consumption by AAP bacteria. The cell size of AAP bacteria was 50% bigger than the size of other bacteria, about the same difference on average as measured for activity. The abundance of AAP bacteria was negatively correlated and their activity positively correlated with light availability in the water column, although light did not affect 3H-leucine incorporation in light–dark experiments. Our results suggest that AAP bacteria are bigger and more active than other bacteria, and likely contribute more to organic carbon fluxes than indicated by their abundance. PMID:24824666

Leucine incorporation by aerobic anoxygenic phototrophic bacteria in the Delaware estuary.

Science.gov (United States)

Stegman, Monica R; Cottrell, Matthew T; Kirchman, David L

2014-11-01

Aerobic anoxygenic phototrophic (AAP) bacteria are well known to be abundant in estuaries, coastal regions and in the open ocean, but little is known about their activity in any aquatic ecosystem. To explore the activity of AAP bacteria in the Delaware estuary and coastal waters, single-cell (3)H-leucine incorporation by these bacteria was examined with a new approach that combines infrared epifluorescence microscopy and microautoradiography. The approach was used on samples from the Delaware coast from August through December and on transects through the Delaware estuary in August and November 2011. The percent of active AAP bacteria was up to twofold higher than the percentage of active cells in the rest of the bacterial community in the estuary. Likewise, the silver grain area around active AAP bacteria in microautoradiography preparations was larger than the area around cells in the rest of the bacterial community, indicating higher rates of leucine consumption by AAP bacteria. The cell size of AAP bacteria was 50% bigger than the size of other bacteria, about the same difference on average as measured for activity. The abundance of AAP bacteria was negatively correlated and their activity positively correlated with light availability in the water column, although light did not affect (3)H-leucine incorporation in light-dark experiments. Our results suggest that AAP bacteria are bigger and more active than other bacteria, and likely contribute more to organic carbon fluxes than indicated by their abundance.

Colonization of the oral cavity by probiotic bacteria.

Science.gov (United States)

Ravn, I; Dige, I; Meyer, R L; Nyvad, B

2012-01-01

The aim of this study was to investigate if three probiotic bacteria present in the milk product Cultura Dofilus® naturell could be detected in saliva and on oral mucosal surfaces, and if they colonized dental surfaces in situ in 8 caries-inactive individuals after 8 daily exposures to the milk product for up to 3 days. Bacteria were identified by fluorescence in situ hybridization and confocal laser scanning microscopy. While probiotic bacteria were present sporadically in the oral cavity on mucosal surfaces and in saliva after 3 days of frequent use of the probiotic milk, they were not detected on dental surfaces. Probiotic bacteria may thus contribute to general oral health, but their potential role in biofilm-induced dental diseases remains unclear. Copyright © 2012 S. Karger AG, Basel.

Co-existence of Anaerobic Ammonium Oxidation Bacteria and Denitrifying Anaerobic Methane Oxidation Bacteria in Sewage Sludge: Community Diversity and Seasonal Dynamics.

Science.gov (United States)

Xu, Sai; Lu, Wenjing; Mustafa, Muhammad Farooq; Caicedo, Luis Miguel; Guo, Hanwen; Fu, Xindi; Wang, Hongtao

2017-11-01

Anaerobic ammonium oxidation (ANAMMOX) and denitrifying anaerobic methane oxidation (DAMO) have been recently discovered as relevant processes in the carbon and nitrogen cycles of wastewater treatment plants. In this study, the seasonal dynamics of ANAMMOX and DAMO bacterial community structures and their abundance in sewage sludge collected from wastewater treatment plants were analysed. Results indicated that ANAMMOX and DAMO bacteria co-existed in sewage sludge in different seasons and their abundance was positively correlated (P bacteria in autumn and winter indicated that these seasons were the preferred time to favour the growth of ANAMMOX and DAMO bacteria. The community structure of ANNAMOX and DAMO bacteria could also shift with seasonal changes. The "Candidatus Brocadia" genus of ANAMMOX bacteria was mainly recovered in spring and summer, and an unknown cluster was primarily detected in autumn and winter. Similar patterns of seasonal variation in the community structure of DAMO bacteria were also observed. Group B was the dominant in spring and summer, whereas in autumn and winter, group A and group B presented almost the same proportion. The redundancy analysis revealed that pH and nitrate were the most significant factors affecting community structures of these two groups (P < 0.01). This study reported the diversity of ANAMMOX and DAMO in wastewater treatment plants that may be the basis for new nitrogen removal technologies.

Bioaccumulation and chemical modification of Tc by soil bacteria

International Nuclear Information System (INIS)

Henrot, J.

1989-01-01

Bioaccumulation and chemical modification of pertechnetate (TcO 4 -) by aerobically and anaerobically grown soil bacteria and by pure cultures of sulfate-reducing bacteria (Desulfovibrio sp.) were studied to gain insight on the possible mechanisms by which bacteria can affect the solubility of Tc in soil. Aerobically grown bacteria had no apparent effect on TcO 4 -; they did not accumulate Tc nor modify its chemical form. Anaerobically grown bacteria exhibited high bioaccumulation and reduced TcO 4 -, enabling its association with organics of the growth medium. Reduction was a metabolic process and not merely the result of reducing conditions in the growth medium. Association of Tc with bacterial polysaccharides was observed only in cultures of anaerobic bacteria. Sulfate-reducing bacteria efficiently removed Tc from solution and promoted its association with organics. Up to 70% of the total Tc in the growth medium was bioaccumulated and/or precipitated. The remaining Tc in soluble form was entirely associated with organics. Pertechnetate was not reduced by the same mechanism as dissimilatory sulfate reduction, but rather by some reducing agent released in the growth medium. A calculation of the amount of Tc that could be associated with the bacterial biomass present in soil demonstrates that high concentration ratios in cultures do not necessarily imply that bioaccumulation is an important mechanism for long-term retention of Tc in soil

Antioxidant and Antimicrobial Potential of the Bifurcaria bifurcata Epiphytic Bacteria

OpenAIRE

Horta, André; Pinteus, Susete; Alves, Celso; Fino, Nádia; Silva, Joana; Fernandez, Sara; Rodrigues, Américo; Pedrosa, Rui

2014-01-01

This article belongs to the Special Issue Selected Papers from the 14th International Symposium on Marine Natural Products Surface-associated marine bacteria are an interesting source of new secondary metabolites. The aim of this study was the isolation and identification of epiphytic bacteria from the marine brown alga, Bifurcaria bifurcata, and the evaluation of the antioxidant and antimicrobial activity of bacteria extracts. The identification of epiphytic bacteria was determined by 16S...

Social Behaviour in Bacteria

Indian Academy of Sciences (India)

Administrator

the recipient. • Social behaviours can be categorized according to the fitness ... is actually the flagella of symbiotic spirochete bacteria that helps it to swim around .... Normal population. Responsive switching. (Environmental stress). Stochastic.

Ammonia production by human faecal bacteria, and the enumeration, isolation and characterization of bacteria capable of growth on peptides and amino acids

Directory of Open Access Journals (Sweden)

Richardson Anthony J

2013-01-01

Full Text Available Abstract Background The products of protein breakdown in the human colon are considered to be detrimental to gut health. Amino acid catabolism leads to the formation of sulfides, phenolic compounds and amines, which are inflammatory and/or precursors to the formation of carcinogens, including N-nitroso compounds. The aim of this study was to investigate the kinetics of protein breakdown and the bacterial species involved. Results Casein, pancreatic casein hydrolysate (mainly short-chain peptides or amino acids were incubated in vitro with suspensions of faecal bacteria from 3 omnivorous and 3 vegetarian human donors. Results from the two donor groups were similar. Ammonia production was highest from peptides, followed by casein and amino acids, which were similar. The amino acids metabolized most extensively were Asp, Ser, Lys and Glu. Monensin inhibited the rate of ammonia production from amino acids by 60% (P = 0.001, indicating the involvement of Gram-positive bacteria. Enrichment cultures were carried out to investigate if, by analogy with the rumen, there was a significant population of asaccharolytic, obligately amino acid-fermenting bacteria (‘hyper-ammonia-producing’ bacteria; HAP in the colon. Numbers of bacteria capable of growth on peptides or amino acids alone averaged 3.5% of the total viable count, somewhat higher than the rumen. None of these were HAP, however. The species enriched included Clostridium spp., one of which was C. perfringens, Enterococcus, Shigella and Escherichia coli. Conclusions Protein fermentation by human faecal bacteria in the absence of sugars not only leads to the formation of hazardous metabolic products, but also to the possible proliferation of harmful bacteria. The kinetics of protein metabolism were similar to the rumen, but HAP bacteria were not found.

Bacteria Associated with Fresh Tilapia Fish (Oreochromis niloticus ...

African Journals Online (AJOL)

acer

Keywords: Bacteria, Tilapia fish and Sokoto central market. INTRODUCTION ... The bacteria are transmitted by fish that have made contact ... with which a product spoils is also related to the .... Base on the percentage frequency of occurance ,.

[Screening endophytic bacteria against plant-parasitic nematodes].

Science.gov (United States)

Peng, Shuang; Yan, Shuzhen; Chen, Shuanglin

2011-03-01

Plant-parasite nematode is one of the most important pathogens in plant. Our objective is to screen endophytic bacteria against plant-parasitic nematodes from plant. Endophytic bacteria were isolated and screened by testing their metabolite against Bursaphelenchus xylophilus in vitro. Those strains inhibiting B. xylophilus were selected to culture in liquid medium and fermentation conditions were optimized by orthogonal test. The stability of the antinematode substances was evaluated by various. In addition, four strains were identified by 16SrDNA sequence analysis. In total 13 strains of endophytic bacteria secreting antinematode metabolite were isolated from 6 species of plant. The supernatant of the fermentation broth of these endophytic bacteria gave 100% mortality of nematodes after treated as the follows: 1 ml each was mixed with 0.2 ml of the suspension of nematodes (2000 nematodes/ml) then incubated at 250C for 24 h, some of which could led to leakage or dissolution of nematodes. Among them, four strains, BCM2, SZ5, CCM7 and DP1, showed stronger activity than others. The supernatants diluted three times also gave not less than 95% mortality after 24 h treatment, and those from DP1 and SZ5 even gave 100% mortality. The fermentation conditions of the four strains were optimized and the antinematode activity grew up four times after optimization. The antinematode substances of these strains were found stable when treated with protease or heating or stored at 4 degrees C after 100 days, while instable when treated with acid or alkali. DP1 and CCM7 were identified to be Bacillus subtilis, while SZ5 and BCM2 to be Bacillus cereus. Endophytic bacteria secreting antinematode metabolite were found in economic crops. The metabolite of some strains showed strong and stable antinematode activity. Our results indicate the real potential of biocontrol by endophytic bacteria.

Pepsin homologues in bacteria

Directory of Open Access Journals (Sweden)

Bateman Alex

2009-09-01

Full Text Available Abstract Background Peptidase family A1, to which pepsin belongs, had been assumed to be restricted to eukaryotes. The tertiary structure of pepsin shows two lobes with similar folds and it has been suggested that the gene has arisen from an ancient duplication and fusion event. The only sequence similarity between the lobes is restricted to the motif around the active site aspartate and a hydrophobic-hydrophobic-Gly motif. Together, these contribute to an essential structural feature known as a psi-loop. There is one such psi-loop in each lobe, and so each lobe presents an active Asp. The human immunodeficiency virus peptidase, retropepsin, from peptidase family A2 also has a similar fold but consists of one lobe only and has to dimerize to be active. All known members of family A1 show the bilobed structure, but it is unclear if the ancestor of family A1 was similar to an A2 peptidase, or if the ancestral retropepsin was derived from a half-pepsin gene. The presence of a pepsin homologue in a prokaryote might give insights into the evolution of the pepsin family. Results Homologues of the aspartic peptidase pepsin have been found in the completed genomic sequences from seven species of bacteria. The bacterial homologues, unlike those from eukaryotes, do not possess signal peptides, and would therefore be intracellular acting at neutral pH. The bacterial homologues have Thr218 replaced by Asp, a change which in renin has been shown to confer activity at neutral pH. No pepsin homologues could be detected in any archaean genome. Conclusion The peptidase family A1 is found in some species of bacteria as well as eukaryotes. The bacterial homologues fall into two groups, one from oceanic bacteria and one from plant symbionts. The bacterial homologues are all predicted to be intracellular proteins, unlike the eukaryotic enzymes. The bacterial homologues are bilobed like pepsin, implying that if no horizontal gene transfer has occurred the duplication

The growth of bacteria on organic compounds in drinking water

NARCIS (Netherlands)

Kooij, van der D.

1984-01-01

Growth ("regrowth") of bacteria In drinking water distribution systems results in a deterioration of the water quality. Regrowth of chemoheterotrophic bacteria depends on the presence of organic. compounds that serve as a nutrient source for these bacteria. A batch-culture technique was

Threats and opportunities of plant pathogenic bacteria.

Science.gov (United States)

Tarkowski, Petr; Vereecke, Danny

2014-01-01

Plant pathogenic bacteria can have devastating effects on plant productivity and yield. Nevertheless, because these often soil-dwelling bacteria have evolved to interact with eukaryotes, they generally exhibit a strong adaptivity, a versatile metabolism, and ingenious mechanisms tailored to modify the development of their hosts. Consequently, besides being a threat for agricultural practices, phytopathogens may also represent opportunities for plant production or be useful for specific biotechnological applications. Here, we illustrate this idea by reviewing the pathogenic strategies and the (potential) uses of five very different (hemi)biotrophic plant pathogenic bacteria: Agrobacterium tumefaciens, A. rhizogenes, Rhodococcus fascians, scab-inducing Streptomyces spp., and Pseudomonas syringae. Copyright © 2013 Elsevier Inc. All rights reserved.

Potency of Amylase-producing Bacteria and Optimization Amylase Activities

Science.gov (United States)

Indriati, G.; Megahati, R. R. P.; Rosba, E.

2018-04-01

Enzymes are capable to act as biocatalyst for a wide variety of chemical reactions. Amylase have potential biotechnological applications in a wide range of industrial processes and account for nearly 30% of the world’s enzyme market. Amylase are extracellular enzymes that catalyze the hydrolysis of internal α-1,4-glycosidic linkages in starch to dextrin, and other small carbohydrate molecules constituted of glucose units. Although enzymes are produced from animal and plant sources, the microbial sources are generally the most suitable for commercial applications. Bacteria from hot springs is widely used as a source of various enzymes, such as amylase. But the amount of amylase-producing bacteria is still very limited. Therefore it is necessary to search sources of amylase-producing bacteria new, such as from hot springs Pariangan. The purpose of this study was to isolation of amylase-producing bacteria from Pariangan hot spring, West Sumatera and amylase activity optimization. The results were obtained 12 isolates of thermophilic bacteria and 5 isolates of amyalse-producing bacteria with the largest amylolytic index of 3.38 mm. The highest amylase activity was obtained at 50°C and pH 7.5.

Interaction of neptunium with humic acid and anaerobic bacteria

International Nuclear Information System (INIS)

Kubota, Takumi; Sasaki, Takayuki; Kudo, Akira

2002-01-01

Humic acid and bacteria play an important role in the migration of radionuclides in groundwaters. The interaction of neptunium with humic acid and anaerobic bacteria has been investigated by liquid/liquid and solid/liquid extraction systems. For liquid/liquid extraction, the apparent complex formation constant, β α was obtained from the distribution between two phases of neptunium. For solid/liquid extraction, the ratio of sorption to bacteria, K d , was measured. K d of humic acid can be evaluated from β α . The large value of β α and K d means strong interaction of neptunium with organisms. In order to examine the effect of the nature of organism on interaction, the interaction with humic acid was compared to that with non-sterilized or sterilized mixed anaerobic bacteria. The value of β α of humate depended on neptunium ion concentration as well as pH, which showed the effect of polyelectrolyte properties and heterogeneous composition of humic acid. The comparison of interaction with humic acid and bacteria indicated that the K d value of humic acid was larger than that of bacteria and more strongly depend on pH. (author)

Occurrence and distribution of nitrogen-scavenging bacteria in marine environment

OpenAIRE

Sugahara, Isao; Kimura, Toshio; Hayashi, Koichiro

1987-01-01

The occurrence and distribution nitrogen-scavenging bacteria in the water of coastal and oceanic of Japan were studied during the Seisui-Maru cruises from 1986 to 1987. Nitroben-scavenging bacteria in the water usually occurred at the level of 10-104 cfu/ml.This value was almost comparable to that of aerobic heterotrophic bacteria. It seems that nitrogen-scavenging bacteria play an important role in the efficient uptake of low levels of nitrogenous compounds in marine enviroment.

[Analysis of Pathogenic Bacteria in Reclaimed Water and Impact of UV Disinfection on the Removal of Pathogenic Bacteria].

Science.gov (United States)

Jing, Ming; Wang, Lei

2016-02-15

In the study, 454-pyrosequencing technology was employed to investigate the species of pathogenic bacteria and the proportion of each pathogen in secondary effluent. Culture-based, qPCR and Q-RT-PCR methods were employed to analyze the removal of indicator (E. coli) and pathogen (Salmonella and Mycobacterium) by ultraviolet (UV) disinfection at a dose of 60 mJ x Cm(-2). The results showed that 11 kinds of pathogenic bacteria were found and the most abundant potentially pathogenic bacteria in the secondary effluent were affiliated with the genera of Clostridium (2.96%), Arcobacter (0.82%) and Mycobacterium (0.36%). 99.9% of culturable E. coli and Salmonella were removed by UV disinfection (60 mJ x cm(-2), however, less than 90% of culturable Mycobacterium were removed. The removal efficiencies of viable E. coli, Salmonella and Mycobacterium were low. Q-RT-PCR seemed to be a promising method for evaluating viable microorganisms in samples. Besides, pathogenic bacteria entered into VBNC state at a UV dose of 60 mJ x cm(-2). Other advanced treatment processes were needed to ensure safe utilization of reclaimed water.

High resistance of some oligotrophic bacteria to ionizing radiation

International Nuclear Information System (INIS)

Nikitin, D.I.; Tashtemirova, M.A.; Pitryuk, I.A.; Sorokin, V.V.; Oranskaya, M.S.; Nikitin, L.E.

1994-01-01

The resistance of seven cultures of eutrophic and oligotrophic bacteria to gamma radiation (at doses up to 360 Gy) was investigated. The bacteria under study were divided into three groups according to their survival ability after irradiation. Methylobacterium organophilum and open-quotes Pedodermatophilus halotoleransclose quotes (LD 50 = 270 Gy) were highly tolerant. By their tolerance, these organisms approached Deinococcus radiodurans. Aquatic ring-shaped (toroidal) bacteria Flectobacillus major and open-quotes Arcocella aquaticaclose quotes (LD 5 = 173 and 210 Gy, respectively) were moderately tolerant. Eutrophic Pseudomonas fluorescens and Escherichia coli (LD 50 = 43 and 38 Gy, respectively) were the most sensitive. X-ray microanalysis showed that in tolerant bacteria the intracellular content of potassium increased and the content of calcium decreased after irradiation. No changes in the element composition of the eutrophic bacterium E. coli were detected. Possible mechanisms of the resistance of oligotrophic bacteria to gamma radiation are discussed

Copper tolerance and virulence in bacteria

Science.gov (United States)

Ladomersky, Erik; Petris, Michael J.

2015-01-01

Copper (Cu) is an essential trace element for all aerobic organisms. It functions as a cofactor in enzymes that catalyze a wide variety of redox reactions due to its ability to cycle between two oxidation states, Cu(I) and Cu(II). This same redox property of copper has the potential to cause toxicity if copper homeostasis is not maintained. Studies suggest that the toxic properties of copper are harnessed by the innate immune system of the host to kill bacteria. To counter such defenses, bacteria rely on copper tolerance genes for virulence within the host. These discoveries suggest bacterial copper intoxication is a component of host nutritional immunity, thus expanding our knowledge of the roles of copper in biology. This review summarizes our current understanding of copper tolerance in bacteria, and the extent to which these pathways contribute to bacterial virulence within the host. PMID:25652326

[Methanotrophic bacteria of acid sphagnum bogs].

Science.gov (United States)

Dedysh, S N

2002-01-01

Acid sphagnum bogs cover a considerable part of the territory of Russia and are an important natural source of biogenic methane, which is formed in their anaerobic layers. A considerable portion of this methane is consumed in the aerobic part of the bog profile by acidophilic methanotrophic bacteria, which comprise the methane filter of sphagnum bogs and decrease CH4 emission to the atmosphere. For a long time, these bacteria escaped isolation, which became possible only after the elucidation of the optimal conditions of their functioning in situ: pH 4.5 to 5.5; temperature, from 15 to 20 degrees C; and low salt concentration in the solution. Reproduction of these conditions and rejection of earlier used media with a high content of biogenic elements allowed methanotrophic bacteria of two new genera and species--Methylocella palustris and Methylocapsa acidophila--to be isolated from the peat of sphagnum bogs of the northern part of European Russia and West Siberia. These bacteria are well adapted to the conditions in cold, acid, oligotrophic sphagnum bogs. They grow in a pH range of 4.2-7.5 with an optimum at 5.0-5.5, prefer moderate temperatures (15-25 degrees C) and media with a low content of mineral salts (200-500 mg/l), and are capable of active nitrogen fixation. Design of fluorescently labeled 16S rRNA-targeted oligonucleotide probes for the detection of Methylocella palustris and Methylocapsa acidophila and their application to the analysis of sphagnum peat samples showed that these bacteria represent dominant populations of methanotrophs with a density of 10(5)-10(6) cells/g peat. In addition to Methylocella and Methylocapsa populations, one more abundant population of methanotrophs was revealed (10(6) cells/g peat), which were phylogenetically close to the genus Methylocystis.

Anaerobic bacteria in wastewater treatment plant.

Science.gov (United States)

Cyprowski, Marcin; Stobnicka-Kupiec, Agata; Ławniczek-Wałczyk, Anna; Bakal-Kijek, Aleksandra; Gołofit-Szymczak, Małgorzata; Górny, Rafał L

2018-03-28

The objective of this study was to assess exposure to anaerobic bacteria released into air from sewage and sludge at workplaces from a wastewater treatment plant (WWTP). Samples of both sewage and sludge were collected at six sampling points and bioaerosol samples were additionally collected (with the use of a 6-stage Andersen impactor) at ten workplaces covering different stages of the technological process. Qualitative identification of all isolated strains was performed using the biochemical API 20A test. Additionally, the determination of Clostridium pathogens was carried out using 16S rRNA gene sequence analysis. The average concentration of anaerobic bacteria in the sewage samples was 5.49 × 10 4 CFU/mL (GSD = 85.4) and in sludge-1.42 × 10 6 CFU/g (GSD = 5.1). In turn, the average airborne bacterial concentration was at the level of 50 CFU/m 3 (GSD = 5.83) and the highest bacterial contamination (4.06 × 10 3  CFU/m 3 ) was found in winter at the bar screens. In total, 16 bacterial species were determined, from which the predominant strains belonged to Actinomyces, Bifidobacterium, Clostridium, Propionibacterium and Peptostreptococcus genera. The analysis revealed that mechanical treatment processes were responsible for a substantial emission of anaerobic bacteria into the air. In both the sewage and air samples, Clostridium perfringens pathogen was identified. Anaerobic bacteria were widely present both in the sewage and in the air at workplaces from the WWTP, especially when the technological process was performed in closed spaces. Anaerobic bacteria formed small aggregates with both wastewater droplets and dust particles of sewage sludge origin and as such may be responsible for adverse health outcomes in exposed workers.

Chemical signaling between plants and plant-pathogenic bacteria.

Science.gov (United States)

Venturi, Vittorio; Fuqua, Clay

2013-01-01

Studies of chemical signaling between plants and bacteria in the past have been largely confined to two models: the rhizobial-legume symbiotic association and pathogenesis between agrobacteria and their host plants. Recent studies are beginning to provide evidence that many plant-associated bacteria undergo chemical signaling with the plant host via low-molecular-weight compounds. Plant-produced compounds interact with bacterial regulatory proteins that then affect gene expression. Similarly, bacterial quorum-sensing signals result in a range of functional responses in plants. This review attempts to highlight current knowledge in chemical signaling that takes place between pathogenic bacteria and plants. This chemical communication between plant and bacteria, also referred to as interkingdom signaling, will likely become a major research field in the future, as it allows the design of specific strategies to create plants that are resistant to plant pathogens.

NC10 bacteria in marine oxygen minimum zones

DEFF Research Database (Denmark)

Padilla, Cory C; Bristow, Laura A; Sarode, Neha

2016-01-01

Bacteria of the NC10 phylum link anaerobic methane oxidation to nitrite denitrification through a unique O2-producing intra-aerobic methanotrophy pathway. A niche for NC10 in the pelagic ocean has not been confirmed. We show that NC10 bacteria are present and transcriptionally active in oceanic....... rRNA and mRNA transcripts assignable to NC10 peaked within the OMZ and included genes of the putative nitrite-dependent intra-aerobic pathway, with high representation of transcripts containing the unique motif structure of the nitric oxide (NO) reductase of NC10 bacteria, hypothesized...

CcpA-dependent carbon catabolite repression in bacteria

NARCIS (Netherlands)

Warner, JB; Lolkema, JS; Warner, Jessica B.

2003-01-01

Carbon catabolite repression (CCR) by transcriptional regulators follows different mechanisms in gram-positive and gram-negative bacteria. In gram-positive bacteria, CcpA-dependent CCR is mediated by phosphorylation of the phosphoenolpyruvate:sugar phosphotransferase system intermediate HPr at a

Antimicrobial properties of probiotic bacteria from various sources

African Journals Online (AJOL)

OKEREKE HOPE C

2012-05-15

May 15, 2012 ... The lactic acid bacteria (LAB), a component of several fermented foods including ... lactic acid bacteria grown in MRS broth for 20 to 24 h using centrifugation .... vacuum packed chill-stored meat has potential application for ...

Heterotrophic utilization of acetate and glucose in Swartvlei, South Africa

International Nuclear Information System (INIS)

Robarts, R.D.

1979-01-01

The utilization of dissolved organic compounds in Swartvlei was measured by the addition of single concentrations of 14 C-labelled acetate and glucose to water samples. The results indicated acetate uptake was greatest in the aerobic zone while glucose was predominantly utilized in the anaerobic zone. With the exception of two months, integral glucose uptake was usually greater than the uptake of acetate. In August and September 1971 acetate was indicated as being utilized predominantly by flagellates and in December 1971 by dinoflagellates. During the remainder of the study, bacteria were assumed to be responsible for the uptake of acetate. The extensive weed beds which surround the upper reaches of Swartvlei may be a major source of acetate and glucose in the pelagic water column

Epithermal neutron activation analysis of CR(VI)-reducer basalt-inhabiting bacteria

International Nuclear Information System (INIS)

Tsibakhashvili, N.Ya.; Kalabegishvili, T.L.; Murusidze, I.G.; Mosulishvili, L.M.; Frontas'eva, M.V.; Kirkesali, E.I.; Aksenova, N.G.; Holman, H.Y.

2005-01-01

Epithermal neutron activation analysis (ENAA) has been applied to studying elemental composition of Cr(VI)-reducer bacteria isolated from polluted basalts from the Republic of Georgia. Cr(VI)-reducing ability of the bacteria was examined by electron spin resonance (ESR) demonstrating that the bacteria differ in the rates of Cr(VI) reduction. A well-pronounced correlation between the ability of the bacteria to accumulate Cr(VI) and their ability to reduce Cr(V) to Cr(III) observed in our experiments is discussed. Elemental analysis of these bacteria also revealed that basalt-inhabiting bacteria are distinguished by relative contents of essential elements such as K, Na, Mg, Fe, Mn, Zn, and Co. A high rate of Cr(III) formation correlates with a high concentration of Co in the bacterium. ENAA detected some similarity in the elemental composition of the bacteria. The relatively high contents of Fe detected in the bacteria (140-340 μg/g of dry weight) indicate bacterial adaptation to the environmental conditions typical of the basalts. The concentrations of at least 12-19 different elements ranging from major- to ultratrace ones were determined in each type of bacteria simultaneously. The range of concentrations spans over 8 orders of magnitude

Identification of marine methanol-utilizing bacteria

Energy Technology Data Exchange (ETDEWEB)

Yamamoto, M; Iwaki, H; Kouno, K; Inui, T

1980-01-01

A taxonomical study of 65 marine methanol-utilizing bacteria is described. They were Gram-negative, non-spore-forming rods with a polar flagellum and had marine bacterial properties and required vitamin B/sub 12/ for growth. All of them assimilated fructose in addition to C/sub 1/-compounds and produced acid oxidatively from fructose. Twenty-four strains assimilated only C/sub 1/-compounds. They were resistant to penicillin, oxytetracycline and 0/129 substance (Vibrio stat), and tolerant to 12% NaCl. Guanine-cytosine contents of deoxyribonucleic acid in typical strains fell in the range of 43.8 to 47.6%. Other morphological and physiological properties were almost the same as those of terrestrial methanol-utilizers. Bacteria in the first group (41 strains) were facultative methylotrophs and were divided into three subgroups by the assimilation of methylated amines, that is, subgroup I (30 strains) assimilated mono-, di- and tri-methylamine, subgroup II (9 strains) assimilated only mono-methylamine, the bacteria of subgroups I and II were named Alteromonas thalassomethanolica sp. nov. and subgroup III (2 strains) did not assimilate methylated amines, and was tentatively assigned as Alteromonas sp. The second group of bacteria (24 strains) was obligate methylotrophs, named Methylomonas thalassica sp. nov. and was divided into subgroup IV (15 strains) which assimilated mono-, di and tri-methylamine and subgroup V (9 strains) which assimilated mono-methylamine.

Developing new bacteria subroutines in the SWAT model

Science.gov (United States)

Fecal bacteria observations from four different sites in Korea and the US demonstrate seasonal variability, showing a significant relationship with temperature (Figure 1); fecal indicator bacteria (FIB) concentrations are relatively higher in summer and lower in winter , including Stillwater river (...

Release of Antibiotic Resistant Bacteria by a Waste Treatment Plant from Romania.

Science.gov (United States)

Lupan, Iulia; Carpa, Rahela; Oltean, Andreea; Kelemen, Beatrice Simona; Popescu, Octavian

2017-09-27

The occurrence and spread of bacterial antibiotic resistance are subjects of great interest, and the role of wastewater treatment plants has been attracting particular interest. These stations are a reservoir of bacteria, have a large range of organic and inorganic substances, and the amount of bacteria released into the environment is very high. The main purpose of the present study was to assess the removal degree of bacteria with resistance to antibiotics and identify the contribution of a wastewater treatment plant to the microbiota of Someşul Mic river water in Cluj county. The resistance to sulfamethoxazole and tetracycline and some of their representative resistance genes: sul1, tet(O), and tet(W) were assessed in this study. The results obtained showed that bacteria resistant to sulphonamides were more abundant than those resistant to tetracycline. The concentration of bacteria with antibiotic resistance changed after the treatment, namely, bacteria resistant to sulfamethoxazole. The removal of all bacteria and antibiotic-resistant bacteria was 98-99% and the degree of removal of bacteria resistant to tetracycline was higher than the bacteria resistant to sulfamethoxazole compared to total bacteria. The wastewater treatment plant not only contributed to elevating ARG concentrations, it also enhanced the possibility of horizontal gene transfer (HGT) by increasing the abundance of the intI1 gene. Even though the treatment process reduced the concentration of bacteria by two orders of magnitude, the wastewater treatment plant in Cluj-Napoca contributed to an increase in antibiotic-resistant bacteria concentrations up to 10 km downstream of its discharge in Someşul Mic river.

Bacterial Feeders, the Nematode Caenorhabditis elegans and the Flagellate Cercomonas longicauda, have different Effects on Outcome of Competition among the Pseudomonas Biocontrol Strains CHA0 and DSS73

DEFF Research Database (Denmark)

Pedersen, Annette; Nybroe, Ole; Winding, Anne

2009-01-01

How bacterial feeding fauna affects colonization and survival of bacteria in soil is not well understood, which constrains the applicability of bacterial inoculants in agriculture. This study aimed to unravel how food quality of bacteria and bacterial feeders with different feeding habits (the......50090 or one of two biocontrol strains P. fluorescens CHA0 or Pseudomonas sp. DSS73) or combinations of two bacterial strains. DSM50090 is a suitable food bacterium, DSS73 is of intermediate food quality, and CHA0 is inedible to the bacterial feeders. Bacterial and protozoan cell numbers were measured...... predation pressure. Hence, the results suggested that the outcome of competition among bacteria depended on their ability to cope with the prevailing bacterial predator....

Coevolution of CRISPR bacteria and phage in 2 dimensions

Science.gov (United States)

Han, Pu; Deem, Michael

2014-03-01

CRISPR (cluster regularly interspaced short palindromic repeats) is a newly discovered adaptive, heritable immune system of prokaryotes. It can prevent infection of prokaryotes by phage. Most bacteria and almost all archae have CRISPR. The CRISPR system incorporates short nucleotide sequences from viruses. These incorporated sequences provide a historical record of the host and predator coevolution. We simulate the coevolution of bacteria and phage in 2 dimensions. Each phage has multiple proto-spacers that the bacteria can incorporate. Each bacterium can store multiple spacers in its CRISPR. Phages can escape recognition by the CRISPR system via point mutation or recombination. We will discuss the different evolutionary consequences of point mutation or recombination on the coevolution of bacteria and phage. We will also discuss an intriguing ``dynamic phase transition'' in the number of phage as a function of time and mutation rate. We will show that due to the arm race between phages and bacteria, the frequency of spacers and proto-spacers in a population can oscillate quite rapidly.

Active targeting of tumor cells using light emitting bacteria

International Nuclear Information System (INIS)

Moon, Sung Min; Min, Jung Joon; Hong, Yeong Jin; Kim, Hyun Ju; Le, Uuenchi N.; Rhee, Joon Haeng; Song, Ho Chun; Heo, Young Jun; Bom, Hee Seung; Choy, Hyon E

2004-01-01

The presence of bacteria and viruses in human tumors has been recognized for more than 50 years. Today, with the discovery of bacterial strains that specifically target tumors, and aided by genomic sequencing and genetic engineering, there is new interest in the use of bacteria as tumor vectors. Here, we show that bacteria injected intravenously into live animals entered and replicated in solid tumors and metastases using the novel imaging technology of biophotonics. Bioluminescence operon (LuxCDABE) or fluorescence protein, GFP) has been cloned into pUC19 plasmid to engineer pUC19lux or pUC19gfp. Engineered plasmid was transformed into different kinds of wild type (MG1655) or mutant E. coli (DH5, ppGpp, fnr, purE, crpA, flagella, etc.) strains to construct light emitting bacteria. Xenograft tumor model has been established using CT26 colon cancer cell line. Light emitting bacteria was injected via tail vein into tumor bearing mouse. In vivo bioluminescence imaging has been done after 20 min to 14 days of bacterial injection. We observed localization of tumors by light-emitting E. coli in tumor (CT-26) bearing mice. We confirmed the presence of light-emitting bacteria under the fluorescence microscope with E. coli expressing GFP. Althoug varying mutants strain with deficient invading function has been found in tumor tissues, mutant strains of movement (flagella) couldn't show any light signal from the tumor tissue under the cooled CCD camera, indicating bacteria may actively target the tumor cells. Based on their 'tumor-finding' nature, bacteria may be designed to carry multiple genes or drugs for detection and treatment of cancer, such as prodrug-converting enzymes, toxins, angiogenesis inhibitors and cytokines

Resuscitation effects of catalase on airborne bacteria.

OpenAIRE

Marthi, B; Shaffer, B T; Lighthart, B; Ganio, L

1991-01-01

Catalase incorporation into enumeration media caused a significant increase (greater than 63%) in the colony-forming abilities of airborne bacteria. Incubation for 30 to 60 min of airborne bacteria in collection fluid containing catalase caused a greater than 95% increase in colony-forming ability. However, catalase did not have any effects on enumeration at high relative humidities (80 to 90%).

Thermophilic, lignocellulolytic bacteria for ethanol production: current state and perspectives

DEFF Research Database (Denmark)

Chang, Tinghong; Yao, Shuo

2011-01-01

of cellulolytic and saccharolytic thermophilic bacteria for lignocellulosic ethanol production because of their unique properties. First of all, thermophilic bacteria possess unique cellulolytic and hemicellulolytic systems and are considered as potential sources of highly active and thermostable enzymes...... for efficient biomass hydrolysis. Secondly, thermophilic bacteria ferment a broad range of carbohydrates into ethanol, and some of them display potential for ethanologenic fermentation at high yield. Thirdly, the establishment of the genetic tools for thermophilic bacteria has allowed metabolic engineering......, in particular with emphasis on improving ethanol yield, and this facilitates their employment for ethanol production. Finally, different processes for second-generation ethanol production based on thermophilic bacteria have been proposed with the aim to achieve cost-competitive processes. However, thermophilic...

Elective culture of bacteria used in bioleaching on pyrrhotite

Institute of Scientific and Technical Information of China (English)

邱冠周; 覃文庆; 蓝卓越; 黎维中

2003-01-01

Elective culture of bacteria on pyrrhotite was researched, and the selected bacteria were tested on bi-oleaching of marmatite and zinc sulfide ore. The results show that the microorganism cultured on pyrrhotite with va-rious S/Fe ratios is a mixed culture of thiobacillus ferrooxidans and thiobacillus thiooxidans, of which the integral ac-tivity and the oxidation capability of Fe2+ and S are enhanced. With the high Fe and low S content of pyrrhotite, the oxida-tion capacity of ferrous ion is improved; on the contrary, the oxidation capacity of sulfur is advanced. The bioleaching ca-pacity of bacteria cultured on marmatite is better than that of the bacteria cultivated by conventional methods.

The determination and arrangement of a combination of enzyme lactate dehydrogenase of bacteria Acinetobacter sp. as a device the identity important bacteria agent composts

Science.gov (United States)

Sukmawati, D.; Puspitaningrum, R.; Muzajjanah

2017-07-01

The number of garbage generated by the industry or society is a usual problem encountered by almost all urban centers, especially large cities such as Jakarta. Waste prevention strategy required quickly and accurately. One strategy for tackling the Junk was getting lactic acid-producing bacteria. It has been shown that lactic acid can increase the acceleration of organic matter such as an overhaul of lignin and cellulose as well as out causing toxic compounds arising from decay. This research will be conducted on the determination and characterization of the enzyme-producing compost bacteria LDH lactate dehydrogenase LDH - which in isolation from the garbage Landfill Rawasari. Methodology: Research carried out consists: isolation of lactic acid-producing bacteria; identification of microscopic, macroscopic and staining Gram; cellulose assay, and optimization of PCR conditions LDH enzymes producing bacteria. Isolation is performed by dilution method and the direct method. As many as 5-point sampling. Each stage is conducted from 10 grams of soil from the top surface of the compost. Isolation results obtained 100 isolate the bacteria. Base on the characteristic of macroscopic and microscopic observations retrieved 14 isolates of bacteria have shaped rods and brought forth a negative kind of Gram positive staining. Bacterial isolates with codes (BK1; BK3; BK4; BK5; BK6; BK7; BK8; BK9; BK10; BK11: BK12; BK 13). The potential bacteria with ability produce lactate dehydrogenase was BK1 and BK3. Base for analysis phylogenetic there was identification bacteria bak1 and bak3 where Acinetobacter sp.

Extracellular communication in bacteria

DEFF Research Database (Denmark)

Chhabra, S.R.; Philipp, B.; Eberl, L.

2005-01-01

molecules, in different Gram-positive and Gram-negative bacteria they control pathogenicity, secondary metabolite production, biofilm differentiation, DNA transfer and bioluminescence. The development of biosensors for the detection of these signal molecules has greatly facilitated their subsequent chemical...

Disinfection of bacteria attached to granular activated carbon.

Science.gov (United States)

LeChevallier, M W; Hassenauer, T S; Camper, A K; McFeters, G A

1984-01-01

Heterotrophic plate count bacteria, coliform organisms, and pathogenic microorganisms attached to granular activated carbon particles were examined for their susceptibility to chlorine disinfection. When these bacteria were grown on carbon particles and then disinfected with 2.0 mg of chlorine per liter (1.4 to 1.6 mg of free chlorine residual per liter after 1 h) for 1 h, no significant decrease in viable counts was observed. Washed cells attached to the surface of granular activated carbon particles showed similar resistance to chlorine, but a progressive increase in sublethal injury was found. Observations made by scanning electron microscope indicated that granular activated carbon was colonized by bacteria which grow in cracks and crevices and are coated by an extracellular slime layer. These data suggest a possible mechanism by which treatment and disinfection barriers can be penetrated and pathogenic bacteria may enter drinking water supplies. Images PMID:6508306

Motility of magnetotactic bacteria/MTB to Geomagnetic fields

Science.gov (United States)

Hidajatullah-Maksoed, Fatahillah

2016-03-01

Bacteria with motility directed by a local geomagnetic fields have been observed in marine sediments'' discussed by R. Blakemore, 1975. Magnetotactic bacteria/MTB discovered in 1963 by Salvatore Bellini. For ``off-axis electron holography in the transmission electron microscope was used to correlates the physical & magnetic microstructure of magnetite nanocrystals in magnetotactic bacteria'' sought ``single-domain magnetite in hemopelagic sediments'' from JF Stolz. Otherwise, for potential source of bioproducts- product meant from result to multiplier -of magnetotactic bacteria[ACV Araujo, et.al, 2014 ] of marine drugs retrieved the `measurement of cellular chemotaxis with ECIS/Taxis, from KM Pietrosimone, 2012, whereas after ``earth magnetic field role on small living models'' are other interpretation of ``taxis'' as a movement of a cell instead usual ``tax'' for yew's taxus cuspidate, hired car & taxes in financial realms. Acknowledgements to HE. Mr. H. TUK SETYOHADI, Jl. Sriwijaya Raya 3, South-Jakarta, INDONESIA.

Marine echinoderms as reservoirs of antimicrobial resistant bacteria

Directory of Open Access Journals (Sweden)

Catarina Marinho

2014-06-01

Full Text Available Echinoderms are benthic animals that play an important ecological role in marine communities occupying diverse trophic levels in the marine food chains. The majority of echinoderms feed on small particles of edible matter, although they can eat many kinds of food (Clark, 1968. Although, some echinoderms species has been facing an emerging demand for human consumption, particularly in Asian and Mediterranean cuisine, where these animals can be eaten raw (Kelly, 2005; Micael et al., 2009. Echinoderms own an innate immune mechanism that allows them to defend themselves from high concentrations of bacteria, viruses and fungus they are often exposed, on marine sediment (Janeway and Medzhitov, 1998, Cooper, 2003. The most frequent genera of gut bacteria in echinoderms are Vibrio, Pseudomonas, Flavobacterium, and Aeromonas; nevertheless Enterococcus spp. and Escherichia coli are also present (Harris, 1993; Marinho et al., 2013. Moreover, fecal resistant bacteria found in the aquatic environment might represent an index of marine pollution (Foti et al., 2009, Kummerer, 2009. Several studies had been lead in order to identify environmental reservoirs for antibiotic-resistant bacteria in populations of fish, echinoderms and marine mammals, and they all support the thesis that these animals may serve as reservoirs since they had acquired resistant microbial species (Johnson et al., 1998, Marinho et al., 2013, Miranda and Zemelman, 2001. However, to our knowledge, there are only available in bibliography one study of antimicrobial resistant bacteria isolated from marine echinoderms (Marinho et al., 2013, which stats that their provenience in this environment is still unclear. Antimicrobial resistance outcomes from the intensive use of antimicrobial drugs in human activities associated with various mechanisms for bacteria genetic transfer (Barbosa and Levy, 2000, Coque et al., 2008. Antibiotic-resistant bacteria enter into water environments where they are

Fecal indicator bacteria at Havana Bay

International Nuclear Information System (INIS)

Lopez Perez, Lisse; Gomez D'Angelo, Yamiris; Beltran Gonzalez, Jesus; Alvarez Valiente, Reinaldo

2013-01-01

Aims: Fecal indicator bacteria concentrations were evaluated in Havana Bay. Methods: Concentrations of traditional fecal indicator bacteria were calculated between April 2010 and February 2011, by MPN methods. Concentrations of thermo tolerant coliform (CTT), Escherichia coli, fecal streptococci (EF), intestinal enterococci (ENT) in seawater, and Clostridium perfringens in sediment surface, were determined. Results: CTT and E. coli levels were far above Cuban water quality standard for indirect contact with water, showing the negative influence of sewage and rivers on the bay. The EF and ENT were measured during sewage spills at the discharge site and they were suitable indicators of fecal contamination, but these indicators didn't show the same behavior in other selected sites. This result comes from its well-known inactivation by solar light in tropical zones and the presumable presence of humid acids in the waters of the bay. Conclusion: Fecal indicator bacteria and its statistical relationships reflect recent and chronic fecal contamination at the bay and near shores.

Alkaline phosphatase activity of rumen bacteria.

Science.gov (United States)

Cheng, K J; Costerton, J W

1977-11-01

Of the 54 strains of rumen bacteria examined for alkaline phosphatase (APase) production, 9 of 33 gram-negative strains and none of 21 gram-positive strains produced the enzyme. The APase of the cells of the three strains of Bacteroides ruminicola that produced significant amounts of the enzyme was located in the periplasmic area of the cell envelope, whereas the enzyme was located in the strains of Selenomonas ruminantium and Succinivibrio dextrinosolvens was associated with the outer membrane. The localization of APase production in the cells of natural populations of rumen bacteria from hay-fed sheep was accomplished by reaction product deposition, and both the proportion of APase-producing bacteria and the location of the enzyme in the cell envelope of the producing cells could be determined. We suggest that this procedure is useful in detecting shifts in the bacterial population and the release of cell-bound APase that accompany feedlot bloat and other sequelae of dietary manipulation in ruminants.

Topological Defects in a Living Nematic Ensnare Swimming Bacteria

Science.gov (United States)

Genkin, Mikhail M.; Sokolov, Andrey; Lavrentovich, Oleg D.; Aranson, Igor S.

2017-01-01

Active matter exemplified by suspensions of motile bacteria or synthetic self-propelled particles exhibits a remarkable propensity to self-organization and collective motion. The local input of energy and simple particle interactions often lead to complex emergent behavior manifested by the formation of macroscopic vortices and coherent structures with long-range order. A realization of an active system has been conceived by combining swimming bacteria and a lyotropic liquid crystal. Here, by coupling the well-established and validated model of nematic liquid crystals with the bacterial dynamics, we develop a computational model describing intricate properties of such a living nematic. In faithful agreement with the experiment, the model reproduces the onset of periodic undulation of the director and consequent proliferation of topological defects with the increase in bacterial concentration. It yields a testable prediction on the accumulation of bacteria in the cores of +1 /2 topological defects and depletion of bacteria in the cores of -1 /2 defects. Our dedicated experiment on motile bacteria suspended in a freestanding liquid crystalline film fully confirms this prediction. Our findings suggest novel approaches for trapping and transport of bacteria and synthetic swimmers in anisotropic liquids and extend a scope of tools to control and manipulate microscopic objects in active matter.

Low field orientation magnetic separation methods for magnetotactic bacteria

International Nuclear Information System (INIS)

Moeschler, F.D.

1999-01-01

Microbial biomineralisation of iron often results in a biomass that is magnetic and can be separated from water systems by the application of a magnetic field. Magnetotactic bacteria form magnetic membrane bound crystals within their structure, generally of magnetite. In nature, this enables magnetotactic bacteria to orientate themselves with respect to the local geomagnetic field. The bacteria then migrate with flagellar driven motion towards their preferred environment. This property has been harnessed to produce a process in which metal loaded magnetotactic bacteria can be recovered from a waste stream. This process is known as orientation magnetic separation. Several methods exist which permit the unique magnetic properties of individual magnetotactic bacteria to be studied, such as U-turn analysis, transmission electron microscopy and single wire cell studies. In this work an extension of U-turn analysis was developed. The bacteria were rendered non-motile by the addition of specific metal ions and the resulting 'flip time' which occurs during a field reversal enabled the magnetic moment of individual bacteria to be determined. This method proved to be much faster and more accurate than previous methods. For a successful process to be developed, large scale culturing of magnetotactic bacteria is required Experiments showed that culture vessel geometry was an important factor for high-density growth. Despite intensive studies reproducible culturing at volumes exceeding one litre was not achieved. This work showed that numerous metal ions rendered magnetotactic bacteria non-motile at concentrations below 10 ppm. Sequential adaptation raised typical levels to in excess of 100 ppm for a number of ions. such as zinc and tin. However, specific ions. such as copper or nickel, remained motility inhibiting at lower concentrations. To achieve separation using orientation magnetic separation, motile, field susceptible MTB are required. Despite successful adaptation, the

A study on the radionuclide transport by bacteria in geologic media

International Nuclear Information System (INIS)

Han, Byoung Sub

1997-02-01

The purpose of this paper is to provide a methodology to develop a predictive model based on a conceptual three phase system and to investigate the influence of bacteria and their generation on the transport of radionuclide in porous and fractured media. The mass balance for bacteria, substrate and radionuclide were formulated. To illustrate the model simply, an equilibrium condition was assumed to partition the substrate, bacteria and radionuclide concentrations between the solid soil matrix, aqueous phase, rock matrix and bacterial surface. From the numerical calculation of the radionuclide transport in the presence of bacteria, it was found that the growth of bacteria and supplied primary substrate as limiting or stimulating growth factor of bacteria are the most important factors of the radionuclide transport. We also found that, depend on the transport of bacteria the temporal and spatial distribution of radionuclide concentration was significantly altered. The model proposed in this study will improve the evaluation of the role of the bacteria in the transport of radionuclide in groundwater systems. Furthermore, this model would be usefully utilized in analyzing the important role of colloidal particulate on the overall performance of radioactive waste safety

A Feasibility Study for Microwave Breast Cancer Detection Using Contrast-Agent-Loaded Bacterial Microbots

Directory of Open Access Journals (Sweden)

Yifan Chen

2013-01-01

Full Text Available We propose a new approach to microwave breast tumor sensing and diagnosis based on the use of biocompatible flagellated magnetotactic bacteria (MTB adapted to operate in human microvasculature. It has been verified experimentally by Martel et al. that externally generated magnetic gradients could be applied to guide the MTB along preplanned routes inside the human body, and a nanoload could be attached to these bacterial microbots. Motivated by these useful properties, we suggest loading a nanoscale microwave contrast agent such as carbon nanotubes (CNTs or ferroelectric nanoparticles (FNPs onto the MTB in order to modify the dielectric properties of tissues near the agent-loaded bacteria. Subsequently, we propose a novel differential microwave imaging (DMI technique to track simultaneously multiple swarms of MTB microbots injected into the breast. We also present innovative strategies to detect and localize a breast tissue malignancy and estimate its size via this DMI-trackable bacterial microrobotic system. Finally, we use an anatomically realistic numerical breast phantom as a platform to demonstrate the feasibility of this tumor diagnostic method.

Tuning Bacterial Hydrodynamics with Magnetic Fields: A Path to Bacterial Robotics

Science.gov (United States)

Pierce, Christopher; Mumper, Eric; Brangham, Jack; Wijesinghe, Hiran; Lower, Stephen; Lower, Brian; Yang, Fengyuan; Sooryakumar, Ratnasingham

Magnetotactic Bacteria (MTB) are a group of motile prokaryotes that synthesize chains of lipid-bound, magnetic nano-particles. In this study, the innate magnetism of these flagellated swimmers is exploited to explore their hydrodynamics near confining surfaces, using the magnetic field as a tuning parameter. With weak (Gauss), uniform, external, magnetic ?elds and the field gradients arising from micro-magnetic surface patterns, the relative strength of hydrodynamic, magnetic and ?agellar force components is tuned through magnetic control of the bacteria's orientation and position. In addition to direct measurement of several hydrodynamic quantities related to the motility of individual cells, their tunable dynamics reveal a number of novel, highly controllable swimming behaviors with potential value in micro-robotics applications. Specifically, the experiments permit the MTB cells to be directed along parallel or divergent trajectories, suppress their flagellar forces through magnetic means, and induce transitions between planar, circulating trajectories and drifting, vertically oriented ``top-like'' motion. The implications of the work for fundamental hydrodynamics research as well as bacterially driven robotics applications will be discussed.

Biochanin A improves fiber fermentation by cellulolytic bacteria

Science.gov (United States)

The objective was to determine the effect of the isoflavone biochanin A (BCA) on rumen cellulolytic bacteria and consequent fermentative activity. When bovine microbial rumen cell suspensions (n = 3) were incubated (24 h, 39 °C) with ground hay, cellulolytic bacteria proliferated, short chain fatty...

Antimicrobial resistance in aerobic bacteria isolated from oral ...

African Journals Online (AJOL)

... varied antimicrobial susceptibility patterns. The oral cavities of hunting dogs are laden with multi-drug resistant bacteria of significant public health importance that could be transferred to humans through contaminated hunted games and bite wound. Keywords: Aerobic bacteria, Antimicrobial resistance, Dogs, Oral cavity, ...

Hydrocarbon degradation potentials of bacteria isolated from spent ...

African Journals Online (AJOL)

Hydrocarbon degradation potentials of bacteria isolated from spent lubricating oil contaminated soil. ... This study has shown that resident bacteria strains in lubricating oil contaminated soils have potential application in the bioremediation of oil polluted sites and enhance the possibility of developing models and strategies ...

Screening of endophytic plant growth-promoting bacteria isolated ...

African Journals Online (AJOL)

Probiotic bacteria, inhabiting the endosphere of plants, presents a major opportunity to develop cheap and eco-friendly alternatives to synthetic agrochemicals. Using standard microbiological procedures, culturable bacteria were isolated from the endosphere (root, stem and leaf) of two Nigerian rice varieties (Ofada and ITA ...

Transmission of Nephridial Bacteria of the Earthworm Eisenia fetida

OpenAIRE

Davidson, Seana K.; Stahl, David A.

2006-01-01

The lumbricid earthworms (annelid family Lumbricidae) harbor gram-negative bacteria in their excretory organs, the nephridia. Comparative 16S rRNA gene sequencing of bacteria associated with the nephridia of several earthworm species has shown that each species of worm harbors a distinct bacterial species and that the bacteria from different species form a monophyletic cluster within the genus Acidovorax, suggesting that there is a specific association resulting from radiation from a common b...

[Regulating acid stress resistance of lactic acid bacteria--a review].

Science.gov (United States)

Wu, Chongde; Huang, Jun; Zhou, Rongqing

2014-07-04

As cell factories, lactic acid bacteria are widely used in food, agriculture, pharmaceutical and other industries. Acid stress is one the important survival challenges encountered by lactic acid bacteria both in fermentation process and in the gastrointestinal tract. Recently, the development of systems biology and metabolic engineering brings unprecedented opportunity for further elucidating the acid tolerance mechanisms and improving the acid stress resistance of lactic acid bacteria. This review addresses physiological mechanisms of lactic acid bacteria during acid stress. Moreover, strategies to improve the acid stress resistance of lactic acid were proposed.

Tolerance of anaerobic bacteria to chlorinated solvents.

Science.gov (United States)

Koenig, Joanna C; Groissmeier, Kathrin D; Manefield, Mike J

2014-01-01

The aim of this research was to evaluate the effects of four chlorinated aliphatic hydrocarbons (CAHs), perchloroethene (PCE), carbon tetrachloride (CT), chloroform (CF) and 1,2-dichloroethane (1,2-DCA), on the growth of eight anaerobic bacteria: four fermentative species (Escherichia coli, Klebsiella sp., Clostridium sp. and Paenibacillus sp.) and four respiring species (Pseudomonas aeruginosa, Geobacter sulfurreducens, Shewanella oneidensis and Desulfovibrio vulgaris). Effective concentrations of solvents which inhibited growth rates by 50% (EC50) were determined. The octanol-water partition coefficient or log Po/w of a CAH proved a generally satisfactory measure of its toxicity. Most species tolerated approximately 3-fold and 10-fold higher concentrations of the two relatively more polar CAHs CF and 1,2-DCA, respectively, than the two relatively less polar compounds PCE and CT. EC50 values correlated well with growth rates observed in solvent-free cultures, with fast-growing organisms displaying higher tolerance levels. Overall, fermentative bacteria were more tolerant to CAHs than respiring species, with iron- and sulfate-reducing bacteria in particular appearing highly sensitive to CAHs. These data extend the current understanding of the impact of CAHs on a range of anaerobic bacteria, which will benefit the field of bioremediation.

Bacteria of Phlebotominae Sand Flies Collected in Western Iran

Directory of Open Access Journals (Sweden)

Somayeh Rafatbakhsh-Iran

2015-08-01

Full Text Available Microorganisms particularly bacteria presenting in insects such as Phlebotominae may play an important role in the epidemiology of human infectious disease. Nowadays, because of vector implications, the routine methods of controlling and spraying have no more beneficial effects on vectors and reservoirs. Little knows about the prevalence and diversity of sand fly bacteria. The main objective of this study was to determine the presence of bacteria of phlebotominae sand flies collected in Hamadan, west of Iran. This information is important in order to development of vector control strategies. The microbial flora of Phlebotomus papatasi and P. sergenti the main vector of Cutaneous Leishmaniasis in the old world, were investigated. We characterized 8 bacteria, including 5 Gram-negative bacteria: Acinetobacter lwoffii, Pseudomonas aeruginosa, Enterobacter cloacae, Edvardsiela sp. and Proteus mirabilis and Gram-positive bacteria: Bacillus subtilis, Staphylococcus saprophyticus and Micrococcus luteus. Our study provides some data on the microbiota diversity of field-collected sand flies for the first time in Hamadan. Our results indicate that there is a range of variation of aerobic bacteria inhabiting sand fly, which possibly reflect the ecological condition of the habitat where the fly breeds. Microbiota is increasingly regarded as an important factor for modulating vector competence in insect vectors. So, mirobiota can be effects on the biology of phlebotominae and their roles in the sandfly-Leishmania interaction. Further experiments are required to clearly delineate the vectorial role of sand flies. Because it is probable that in the future, factors such as environmental changes, migration and urbanization can ease the transmission of leishmaniasis in this area.

Diversity of root nodule bacteria from leguminous crops

Directory of Open Access Journals (Sweden)

Agrawal Pooja

2016-01-01

Full Text Available In the present study, a total of 353 nodule-associated bacteria were isolated from 220 legume plant samples belonging to Cicer arietinum (85, Glycine max (74, Vigna radiata (21 and Cajanus cajan (40. A total of 224 bacteria were identified as fast-growing Rhizobium spp. on the basis of differential staining (Gram staining and carbol fuchsin staining and biochemical tests. All the isolates were tested for indole acetic acid production (IAA, phosphate solubilization and siderophore production on plate assay. To examine the effect of volatile organic metabolites (VOM and water soluble soil components (WSSC on nodule bacteria, culture conditions were optimized by observing the effects of various parameters such as pH, salt content and temperatures on the growth of bacteria. Selected rhizobia were subjected to random amplified polymorphic DNA (RAPD and amplified ribosomal DNA restriction analysis (ARDRA analysis to identify their species. On the basis of RAPD and ARDRA, 10 isolates were identified as Rhizobium meliloti. In this study, Rhizobium GO4, G16, G20, G77, S43, S81, M07, M37, A15 and A55 were observed as the best candidates among the tested bacteria and can be further used as potent bioinoculants.

Anaerobic Ammonium-Oxidizing Bacteria in Cow Manure Composting.

Science.gov (United States)

Wang, Tingting; Cheng, Lijun; Zhang, Wenhao; Xu, Xiuhong; Meng, Qingxin; Sun, Xuewei; Liu, Huajing; Li, Hongtao; Sun, Yu

2017-07-28

Composting is widely used to transform waste into valuable agricultural organic fertilizer. Anaerobic ammonium-oxidizing (anammox) bacteria play an important role in the global nitrogen cycle, but their role in composting remains poorly understood. In the present study, the community structure, diversity, and abundance of anammox bacteria were analyzed using cloning and sequencing methods by targeting the 16S rRNA gene and the hydrazine oxidase gene ( hzo ) in samples isolated from compost produced from cow manure and rice straw. A total of 25 operational taxonomic units were classified based on 16S rRNA gene clone libraries, and 14 operational taxonomic units were classified based on hzo gene clone libraries. The phylogenetic tree analysis of the 16S rRNA gene and deduced HZO protein sequences from the corresponding encoding genes indicated that the majority of the obtained clones were related to the known anammox bacteria Candidatus "Brocadia," Candidatus "Kuenenia," and Candidatus "Scalindua." The abundances of anammox bacteria were determined by quantitative PCR, and between 2.13 × 10 5 and 1.15 × 10 6 16S rRNA gene copies per gram of compost were found. This study provides the first demonstration of the existence of anammox bacteria with limited diversity in cow manure composting.

Symbiotic Bacteria Enable Olive Fly Larvae to Overcome Host Defenses

International Nuclear Information System (INIS)

Ben-Yosef, Michael; Yuval, Boaz; Pasternak, Zohar; Jurkevitch, Edouard

2016-01-01

Ripe fruit offer readily available nutrients for many animals, including fruit fly larvae (Diptera: Tephritidae) and their associated rot-inducing bacteria. Yet, during most of their ontogeny, fruit remain chemically defended and effectively suppress herbivores and pathogens by high levels of secondary metabolites. Olive flies (Bactrocera oleae) are uniquely able to develop in unripe olives. Unlike other frugivorous tephritids, the larvae maintain bacteria confined within their midgut caeca. We examined the interaction between larvae, their associated bacteria, and fruit chemical defence, hypothesizing that bacterial contribution to larval development is contingent on the phenology of fruit defensive chemistry. We demonstrate that larvae require their natural complement of bacteria (Candidatus Erwinia dacicola: Enterobacteriaceae) in order to develop in unripe olives. Conversely, when feeding on ripe fruit, larval development proceeds independently of these bacteria. Our experiments suggest that bacteria counteract the inhibitory effect of oleuropein—the principal phenolic glycoside in unripe olives. In light of these results, we suggest that the unique symbiosis in olive flies, compared with other frugivorous tephritids, is understood by considering the relationship between the fly, bacteria and fruit chemistry. When applied in an evolutionary context, this approach may also point out the forces which shaped symbioses across the Tephritidae. (author)

Incorporation of therapeutically modified bacteria into gut microbiota inhibits obesity.

Science.gov (United States)

Chen, Zhongyi; Guo, Lilu; Zhang, Yongqin; Walzem, Rosemary L; Pendergast, Julie S; Printz, Richard L; Morris, Lindsey C; Matafonova, Elena; Stien, Xavier; Kang, Li; Coulon, Denis; McGuinness, Owen P; Niswender, Kevin D; Davies, Sean S

2014-08-01

Metabolic disorders, including obesity, diabetes, and cardiovascular disease, are widespread in Westernized nations. Gut microbiota composition is a contributing factor to the susceptibility of an individual to the development of these disorders; therefore, altering a person's microbiota may ameliorate disease. One potential microbiome-altering strategy is the incorporation of modified bacteria that express therapeutic factors into the gut microbiota. For example, N-acylphosphatidylethanolamines (NAPEs) are precursors to the N-acylethanolamide (NAE) family of lipids, which are synthesized in the small intestine in response to feeding and reduce food intake and obesity. Here, we demonstrated that administration of engineered NAPE-expressing E. coli Nissle 1917 bacteria in drinking water for 8 weeks reduced the levels of obesity in mice fed a high-fat diet. Mice that received modified bacteria had dramatically lower food intake, adiposity, insulin resistance, and hepatosteatosis compared with mice receiving standard water or control bacteria. The protective effects conferred by NAPE-expressing bacteria persisted for at least 4 weeks after their removal from the drinking water. Moreover, administration of NAPE-expressing bacteria to TallyHo mice, a polygenic mouse model of obesity, inhibited weight gain. Our results demonstrate that incorporation of appropriately modified bacteria into the gut microbiota has potential as an effective strategy to inhibit the development of metabolic disorders.

Phylogenetic diversity of bacteria associated with toxic and non-toxic ...

African Journals Online (AJOL)

Phylogenetic diversity of bacteria associated with toxic and non-toxic strains of Alexandrium minutum. L Palacios, B Reguera, J Franco, I Marín. Abstract. Marine planktonic dinoflagellates are usually associated with bacteria, some of which seem to have a symbiotic relation with the dinoflagellate cells. The role of bacteria in ...

Frequency of Resistance and Susceptible Bacteria Isolated from Houseflies

Directory of Open Access Journals (Sweden)

B Davari

2010-12-01

Conclusion: Houseflies collected from hospitals and slaughterhouse may be involved in the spread of drug resistant bacteria and may increase the potential of human exposure to drug resistant bacteria.

Detection of Sulphate-Reducing Bacteria and Others Cultivable Facultative Bacteria in Dental Tissues

Directory of Open Access Journals (Sweden)

Lúcio de Souza Gonçalves

2014-01-01

Full Text Available Aim: To detect for the presence of sulphate-reducing bacteria (SRB and evaluate the possible association between SRB and cultivable facultative bacterial of oral sites with different periodontal conditions. Methods: The study was carried out on 9 samples from different oral sites in 8 patients (two samples were collected from the same patient. Material was collected using modified Postgate E culture medium, indicated for the growth and isolation of SRB. In addition, a reducing solution for anaerobic bacteria was used as a transport solution for facultative bacteria and identified by polymerase chain reaction amplification (PCR and sequencing of the 16S rRNA gene. Results: SRB was found in 3 patient samples: the first in a root fragment, the second in a root fragment and a healthy tooth with vertical bone loss and a mobility degree of 3; and the third in a healthy tooth extracted for orthodontic treatment. In the final patient, the cultivable facultative species Lactobacillus casei was identified. Other facultative bacterial species were identified in patient 5 (Kurthia Gibsonii and patient 7 (Pseudomonas aeruginosa. Conclusions: The detection of SRB in different dental tissues with distinct periodontal features demonstrated that new studies need to be developed in order to determine the true role of SRB in the oral microbiota. In addition, it was possible to verify the presence of Lactobacillus casei together with SRB in one sample.

Bacteria, some permanent tenants Space Station; Bacteria, unos inquilinos permanentes de la estacion espacial

Energy Technology Data Exchange (ETDEWEB)

Diaz, B.

2015-07-01

Vacuum cleaners to operate the vacuum or rags with ethanol they are the products of cleaning of the astronauts. Is there tight spaces fully sterilized? It seems not, even in the Space Station International (ISS). When it comes to bacteria, they are able to travel more than 400 kilometers housed in costumes, bodies and interior of the astronauts themselves and settle in a enclosed space where-unlike in a {sup c}leanroom 'terrestre- the air is not recycled. A NASA study has found an abundance of bacteria 'opportunists' which, although harmless on Earth, they might derivasen cause infections in inflammations or skin irritations. Not forgetting those fungi that could damage or affect the infrastructure equipment space. (Author)

Marine snow, organic solute plumes, and optimal chemosensory behavior of bacteria

DEFF Research Database (Denmark)

Kiørboe, Thomas; Jackson, G.A.

2001-01-01

Leaking organic solutes form an elongated plume in the wake of a sinking aggregate. These solutes may both be assimilated by suspended bacteria and guide bacteria with chemokinetic swimming behavior toward the aggregate. We used modifications of previously published models of the flow and concent......Leaking organic solutes form an elongated plume in the wake of a sinking aggregate. These solutes may both be assimilated by suspended bacteria and guide bacteria with chemokinetic swimming behavior toward the aggregate. We used modifications of previously published models of the flow...... behavior was used to examine the potential contribution of aggregate-generated solute plumes for water column bacteria] production. Despite occupying only a small volume fraction, the plumes may provide important growth habitats for free bacteria and account for a significant proportion of water column...

Determination of Ammonia Oxidizing Bacteria and Nitrate Oxidizing Bacteria in Wastewater and Bioreactors

Science.gov (United States)

Francis, Somilez Asya

2014-01-01

The process of water purification has many different physical, chemical, and biological processes. One part of the biological process is the task of ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB). Both play critical roles in the treatment of wastewater by oxidizing toxic compounds. The broad term is nitrification, a naturally occurring process that is carried out by AOB and NOB by using oxidation to convert ammonia to nitrite and nitrite to nitrate. To monitor this biological activity, bacterial staining was performed on wastewater contained in inoculum tanks and biofilm samples from bioreactors. Using microscopy and qPCR, the purpose of this experiment was to determine if the population of AOB and NOB in wastewater and membrane bioreactors changed depending on temperature and hibernation conditions to determine the optimal parameters for AOB/NOB culture to effectively clean wastewater.

Sulphur oxidising bacteria in mangrove ecosystem: A review ...

African Journals Online (AJOL)

Sulphur-oxidizing bacteria such as photoautotrophs, chemolithotrophs and heterotrophs play an important role in the mangrove environment for the oxidation of the toxic sulphide produced by sulphur reducing bacteria and act as a key driving force behind all sulphur transformations in the mangrove ecosystem which is ...

unanswerable questions just as interesting as unculturable bacteria!

Indian Academy of Sciences (India)

First page Back Continue Last page Overview Graphics. UNANSWERABLE QUESTIONS JUST AS INTERESTING AS UNCULTURABLE BACTERIA! How can landmark research be done in a college? What is the need to isolate novel bacteria when the ones already isolated are not completely studied? How can one do ...

Anti-fungal properties of chitinolytic dune soil bacteria

NARCIS (Netherlands)

De Boer, W.; Klein Gunnewiek, P.J.A.; Lafeber, P.; Janse, J.H.; Spit, B.E.; Woldendorp, J.W.

1998-01-01

Anti-fungal properties of chitinolytic soil bacteria may enable them to compete successfully for chitin with fungi. Additionally, the production of chitinase may be part of a lytic system that enables the bacteria to use living hyphae rather than chitin as the actual growth substrate, since chitin

Lactic Acid Bacteria Differentially Activate Natural Killer Cells

DEFF Research Database (Denmark)

Fink, Lisbeth Nielsen; Christensen, Hanne Risager; Frøkiær, Hanne

antigen presenting cells and T-cells. Bacteria translocating across the gastrointestinal mucosa are presumed to gain access to NK cell compartments, as consumption of certain strains of lactic acid bacteria has been shown to increase in vivo NK cytotoxic activity. On-going research in our lab aims...

Damage mechanisms of pathogenic bacteria in drinking water ...

African Journals Online (AJOL)

This study aimed at elucidating the inactivation mechanisms of pathogenic bacteria in drinking water during chlorine and solar disinfection using a simple plating method. The well-known bacterial model Escherichia coli was used as pathogenic bacteria for the experiments. The damage mechanisms of E. coli were ...

[Bacteriophages in the battle against multidrug resistant bacteria

NARCIS (Netherlands)

Meer, J.W.M. van der; Vandenbroucke-Grauls, C.

2018-01-01

Bacteriophages are viruses that infect bacteria. They are highly specific for a bacterial species. The so-called 'lytic phages' can lyse bacteria when they infect them; these phages can be used to treat bacterial infections. Despite a century of experience with phage therapy, the evidence for

EFFECT OF SODIUM PHOSPHATES ON SELECTED FOOD GRADE BACTERIA

Directory of Open Access Journals (Sweden)

Stanislav Kráčmar

2011-04-01

Full Text Available The aim of this study was to examine the inhibitory effect in vitro of selected sodium phosphates (under the corporate names Hexa 68, Hexa 70, Trikrystal, FST, Pyro 52, KPS, Didi on selected gram-positive and gram-negative bacteria. Seven different concentrations of each phosphate were used. Sensitivity of the bacterial strains to phosphates was observed in broth supplemented with salts. In vitro was showed a negative effect of various phosphates on growth of selected gram-positive bacteria. Orthophosphates and diphosphates (pyrophosphates did not have significant inhibitory effect on tested bacteria at neutral pH. With the exception of phosphate Trikrystal has not been found in vitro significant inhibitory effects on gram-negative bacteria.doi:10.5219/141

Expulsion of swimming bacteria by a circular flow

Science.gov (United States)

Sokolov, Andrey; Aronson, Igor

Macroscopic shear flow alters swimming trajectories in a highly nontrivial way and results in dramatic reduction of viscosity and heterogeneous bacterial distributions. We report on experimental and theoretical studies of rapid expulsion of microswimmers, such as motile bacteria, by a circular flow created by a rotating microparticle. We observed a formation of a macroscopic depletion area in a high-shear region, in the vicinity of a microparticle. The rapid migration of bacteria from the shear-rich area is caused by a circular structure of the flow rather than intrinsic random fluctuations of bacteria orientations, in stark contrast to planar shear flow. Our mathematical model revealed that expulsion is a combined effect of motility and alignment by a vortical flow. Our findings offer a novel approach for manipulation of motile microorganisms and shed new light on bacteria-flow interactions. Was supported by the US DOE, Office of Basic Energy Sciences, Division of Materials Science And Engineering, under Contract No. DE AC02-06CH11357.

CRISPR-Cas Technologies and Applications in Food Bacteria.

Science.gov (United States)

Stout, Emily; Klaenhammer, Todd; Barrangou, Rodolphe

2017-02-28

Clustered regularly interspaced short palindromic repeats (CRISPRs) and CRISPR-associated (Cas) proteins form adaptive immune systems that occur in many bacteria and most archaea. In addition to protecting bacteria from phages and other invasive mobile genetic elements, CRISPR-Cas molecular machines can be repurposed as tool kits for applications relevant to the food industry. A primary concern of the food industry has long been the proper management of food-related bacteria, with a focus on both enhancing the outcomes of beneficial microorganisms such as starter cultures and probiotics and limiting the presence of detrimental organisms such as pathogens and spoilage microorganisms. This review introduces CRISPR-Cas as a novel set of technologies to manage food bacteria and offers insights into CRISPR-Cas biology. It primarily focuses on the applications of CRISPR-Cas systems and tools in starter cultures and probiotics, encompassing strain-typing, phage resistance, plasmid vaccination, genome editing, and antimicrobial activity.

A light-induced shortcut in the planktonic microbial loop

Science.gov (United States)

Ptacnik, Robert; Gomes, Ana; Royer, Sarah-Jeanne; Berger, Stella A.; Calbet, Albert; Nejstgaard, Jens C.; Gasol, Josep M.; Isari, Stamatina; Moorthi, Stefanie D.; Ptacnikova, Radka; Striebel, Maren; Sazhin, Andrey F.; Tsagaraki, Tatiana M.; Zervoudaki, Soultana; Altoja, Kristi; Dimitriou, Panagiotis D.; Laas, Peeter; Gazihan, Ayse; Martínez, Rodrigo A.; Schabhüttl, Stefanie; Santi, Ioulia; Sousoni, Despoina; Pitta, Paraskevi

2016-07-01

Mixotrophs combine photosynthesis with phagotrophy to cover their demands in energy and essential nutrients. This gives them a competitive advantage under oligotropihc conditions, where nutrients and bacteria concentrations are low. As the advantage for the mixotroph depends on light, the competition between mixo- and heterotrophic bacterivores should be regulated by light. To test this hypothesis, we incubated natural plankton from the ultra-oligotrophic Eastern Mediterranean in a set of mesocosms maintained at 4 light levels spanning a 10-fold light gradient. Picoplankton (heterotrophic bacteria (HB), pico-sized cyanobacteria, and small-sized flagellates) showed the fastest and most marked response to light, with pronounced predator-prey cycles, in the high-light treatments. Albeit cell specific activity of heterotrophic bacteria was constant across the light gradient, bacterial abundances exhibited an inverse relationship with light. This pattern was explained by light-induced top-down control of HB by bacterivorous phototrophic eukaryotes (PE), which was evidenced by a significant inverse relationship between HB net growth rate and PE abundances. Our results show that light mediates the impact of mixotrophic bacterivores. As mixo- and heterotrophs differ in the way they remineralize nutrients, these results have far-reaching implications for how nutrient cycling is affected by light.

A light-induced shortcut in the planktonic microbial loop

KAUST Repository

Ptacnik, Robert; Gomes, Ana; Royer, Sarah-Jeanne; Berger, Stella A.; Calbet, Albert; Nejstgaard, Jens C.; Gasol, Josep M.; Isari, Stamatina; Moorthi, Stefanie D.; Ptacnikova, Radka; Striebel, Maren; Sazhin, Andrey F.; Tsagaraki, Tatiana M.; Zervoudaki, Soultana; Altoja, Kristi; Dimitriou, Panagiotis D.; Laas, Peeter; Gazihan, Ayse; Martí nez, Rodrigo A.; Schabhü ttl, Stefanie; Santi, Ioulia; Sousoni, Despoina; Pitta, Paraskevi

2016-01-01

Mixotrophs combine photosynthesis with phagotrophy to cover their demands in energy and essential nutrients. This gives them a competitive advantage under oligotropihc conditions, where nutrients and bacteria concentrations are low. As the advantage for the mixotroph depends on light, the competition between mixo- and heterotrophic bacterivores should be regulated by light. To test this hypothesis, we incubated natural plankton from the ultra-oligotrophic Eastern Mediterranean in a set of mesocosms maintained at 4 light levels spanning a 10-fold light gradient. Picoplankton (heterotrophic bacteria (HB), pico-sized cyanobacteria, and small-sized flagellates) showed the fastest and most marked response to light, with pronounced predator-prey cycles, in the high-light treatments. Albeit cell specific activity of heterotrophic bacteria was constant across the light gradient, bacterial abundances exhibited an inverse relationship with light. This pattern was explained by light-induced top-down control of HB by bacterivorous phototrophic eukaryotes (PE), which was evidenced by a significant inverse relationship between HB net growth rate and PE abundances. Our results show that light mediates the impact of mixotrophic bacterivores. As mixo- and heterotrophs differ in the way they remineralize nutrients, these results have far-reaching implications for how nutrient cycling is affected by light.

A light-induced shortcut in the planktonic microbial loop

KAUST Repository

Ptacnik, Robert

2016-07-11

Mixotrophs combine photosynthesis with phagotrophy to cover their demands in energy and essential nutrients. This gives them a competitive advantage under oligotropihc conditions, where nutrients and bacteria concentrations are low. As the advantage for the mixotroph depends on light, the competition between mixo- and heterotrophic bacterivores should be regulated by light. To test this hypothesis, we incubated natural plankton from the ultra-oligotrophic Eastern Mediterranean in a set of mesocosms maintained at 4 light levels spanning a 10-fold light gradient. Picoplankton (heterotrophic bacteria (HB), pico-sized cyanobacteria, and small-sized flagellates) showed the fastest and most marked response to light, with pronounced predator-prey cycles, in the high-light treatments. Albeit cell specific activity of heterotrophic bacteria was constant across the light gradient, bacterial abundances exhibited an inverse relationship with light. This pattern was explained by light-induced top-down control of HB by bacterivorous phototrophic eukaryotes (PE), which was evidenced by a significant inverse relationship between HB net growth rate and PE abundances. Our results show that light mediates the impact of mixotrophic bacterivores. As mixo- and heterotrophs differ in the way they remineralize nutrients, these results have far-reaching implications for how nutrient cycling is affected by light.

Protein-Injection Machines in Bacteria.

Science.gov (United States)

Galán, Jorge E; Waksman, Gabriel

2018-03-08

Many bacteria have evolved specialized nanomachines with the remarkable ability to inject multiple bacterially encoded effector proteins into eukaryotic or prokaryotic cells. Known as type III, type IV, and type VI secretion systems, these machines play a central role in the pathogenic or symbiotic interactions between multiple bacteria and their eukaryotic hosts, or in the establishment of bacterial communities in a diversity of environments. Here we focus on recent progress elucidating the structure and assembly pathways of these machines. As many of the interactions shaped by these machines are of medical importance, they provide an opportunity to develop novel therapeutic approaches to combat important human diseases. Copyright © 2018 Elsevier Inc. All rights reserved.

Epithermal Neutron Activation Analysis (ENAA) of Cr(VI)-reducer Basalt-inhabiting Bacteria

CERN Document Server

Tsibakhashvili, N Ya; Kirkesali, E I; Aksenova, N G; Kalabegishvili, T L; Murusidze, I G; Mosulishvili, L M; Holman, H Y N

2005-01-01

Epithermal neutron activation analysis (ENAA) has been applied to studying elemental composition of Cr(VI)-reducer bacteria isolated from polluted basalts from the Republic of Georgia. Cr(VI)-reducing ability of the bacteria was examined by electron spin resonance (ESR) demonstrating that the bacteria differ in the rates of Cr(VI) reduction. A well-pronounced correlation between the ability of the bacteria to accumulate Cr(V) and their ability to reduce Cr(V) to Cr(III) observed in our experiments is discussed. Elemental analysis of these bacteria also revealed that basalt-inhabiting bacteria are distinguished by relative contents of essential elements such as K, Na, Mg, Fe, Mn, Zn, and Co. A high rate of Cr(III) formation correlates with a high concentration of Co in the bacterium. ENAA detected some similarity in the elemental composition of the bacteria. The relatively high contents of Fe detected in the bacteria (140-340 $\\mu $g/g of dry weight) indicate bacterial adaptation to the environmental condition...

Non-thermal plasma mills bacteria: Scanning electron microscopy observations

International Nuclear Information System (INIS)

Lunov, O.; Churpita, O.; Zablotskii, V.; Jäger, A.; Dejneka, A.; Deyneka, I. G.; Meshkovskii, I. K.; Syková, E.; Kubinová, Š.

2015-01-01

Non-thermal plasmas hold great promise for a variety of biomedical applications. To ensure safe clinical application of plasma, a rigorous analysis of plasma-induced effects on cell functions is required. Yet mechanisms of bacteria deactivation by non-thermal plasma remain largely unknown. We therefore analyzed the influence of low-temperature atmospheric plasma on Gram-positive and Gram-negative bacteria. Using scanning electron microscopy, we demonstrate that both Gram-positive and Gram-negative bacteria strains in a minute were completely destroyed by helium plasma. In contrast, mesenchymal stem cells (MSCs) were not affected by the same treatment. Furthermore, histopathological analysis of hematoxylin and eosin–stained rat skin sections from plasma–treated animals did not reveal any abnormalities in comparison to control ones. We discuss possible physical mechanisms leading to the shred of bacteria under non-thermal plasma irradiation. Our findings disclose how helium plasma destroys bacteria and demonstrates the safe use of plasma treatment for MSCs and skin cells, highlighting the favorability of plasma applications for chronic wound therapy

Corrosion of candidate container materials by Yucca Mountain bacteria

International Nuclear Information System (INIS)

Horn, J; Jones, D; Lian, T; Martin, S; Rivera, A

1999-01-01

Several candidate container materials have been studied in modified Yucca Mountain (YM) ground water in the presence or absence of YM bacteria. YM bacteria increased corrosion rates by 5-6 fold in UNS G10200 carbon steel, and nearly 100-fold in UNS NO4400 Ni-Cu alloy. YM bacteria caused microbiologically influenced corrosion (MIC) through de-alloying or Ni-depletion of Ni-Cu alloy as evidenced by scanning electronic microscopy (SEM) and inductively coupled plasma spectroscopy (ICP) analysis. MIC rates of more corrosion-resistant alloys such as UNS NO6022 Ni-Cr- MO-W alloy, UN's NO6625 Ni-Cr-Mo alloy, and UNS S30400 stainless steel were measured below 0.05 umyr, however YM bacteria affected depletion of Cr and Fe relative to Ni in these materials. The chemical change on the metal surface caused by depletion was characterized in anodic polarization behavior. The anodic polarization behavior of depleted Ni-based alloys was similar to that of pure Ni. Key words: MIC, container materials, YM bacteria, de-alloying, Ni-depletion, Cr-depletion, polarization resistance, anodic polarization,

Antibiotic effects against periodontal bacteria in organ cultured tissue.

Science.gov (United States)

Takeshita, Masaaki; Haraguchi, Akira; Miura, Mayumi; Hamachi, Takafumi; Fukuda, Takao; Sanui, Terukazu; Takano, Aiko; Nishimura, Fusanori

2017-02-01

Mechanical reduction of infectious bacteria by using physical instruments is considered the principal therapeutic strategy for periodontal disease; addition of antibiotics is adjunctive. However, local antibiotic treatment, combined with conventional mechanical debridement, has recently been shown to be more effective in periodontitis subjects with type 2 diabetes. This suggests that some bacteria may invade the inflamed inner gingival epithelium, and mechanical debridement alone will be unable to reduce these bacteria completely. Therefore, we tried to establish infected organ culture models that mimic the inner gingival epithelium and aimed to see the effects of antibiotics in these established models. Mouse dorsal skin epithelia were isolated, and periodontal bacteria were injected into the epithelia. Infected epithelia were incubated with test antibiotics, and colony-forming ability was evaluated. Results indicated that effective antibiotics differed according to injected bacteria and the bacterial combinations tested. Overall, in organ culture model, the combination of amoxicillin or cefdinir and metronidazole compensate for the effects of less effective bacterial combinations on each other. This in vitro study would suggest effective periodontal treatment regimens, especially for severe periodontitis.

Cultivation, detection, and ecophysiology of anaerobic ammonium-oxidizing bacteria.

Science.gov (United States)

Kartal, Boran; Geerts, Wim; Jetten, Mike S M

2011-01-01

Anaerobic ammonium-oxidizing (anammox) bacteria oxidize ammonium with nitrite under anoxic conditions. The anammox process is currently used to remove ammonium from wastewater and contributes significantly to the loss of fixed nitrogen from the oceans. In this chapter, we focus on the ecophysiology of anammox bacteria and describe new methodologies to grow these microorganisms. Now, it is possible to enrich anammox bacteria up to 95% with a membrane bioreactor that removes forces of selection for fast settling aggregates and facilitates the growth of planktonic cells. The biomass from this system has a high anaerobic ammonium oxidation rate (50 fmol NH(4)(+) · cell(-1) day(-1)) and is suitable for many ecophysiological and molecular experiments. A high throughput Percoll density gradient centrifugation protocol may be applied on this biomass for further enrichment (>99.5%) of anammox bacteria. Furthermore, we provide an up-to-date list of commonly used primers and introduce protocols for quantification and detection of functional genes of anammox bacteria in their natural environment. Copyright © 2011 Elsevier Inc. All rights reserved.

Wastewater nutrient removal in a mixed microalgae-bacteria culture: effect of light and temperature on the microalgae-bacteria competition.

Science.gov (United States)

González-Camejo, J; Barat, R; Pachés, M; Murgui, M; Seco, A; Ferrer, J

2018-02-01

The aim of this study was to evaluate the effect of light intensity and temperature on nutrient removal and biomass productivity in a microalgae-bacteria culture and their effects on the microalgae-bacteria competition. Three experiments were carried out at constant temperature and various light intensities: 40, 85 and 125 µE m -2  s -1 . Other two experiments were carried out at variable temperatures: 23 ± 2°C and 28 ± 2°C at light intensity of 85 and 125 µE m -2  s -1 , respectively. The photobioreactor was fed by the effluent from an anaerobic membrane bioreactor. High nitrogen and phosphorus removal efficiencies (about 99%) were achieved under the following operating conditions: 85-125 µE m -2  s -1 and 22 ± 1°C. In the microalgae-bacteria culture studied, increasing light intensity favoured microalgae growth and limited the nitrification process. However, a non-graduated temperature increase (up to 32°C) under the light intensities studied caused the proliferation of nitrifying bacteria and the nitrite and nitrate accumulation. Hence, light intensity and temperature are key parameters in the control of the microalgae-bacteria competition. Biomass productivity significantly increased with light intensity, reaching 50.5 ± 9.6, 80.3 ± 6.5 and 94.3 ± 7.9 mgVSS L -1  d -1 for a light intensity of 40, 85 and 125 µE m -2  s -1 , respectively.

PATHOGENICITY OF BIOFILM BACTERIA

Science.gov (United States)

There is a paucity of information concerning any link between the microorganisms commonly found in biofilms of drinking water systems and their impacts on human health. For bacteria, culture-based techniques detect only a limited number of the total microorganisms associated wit...

Removal of crude petroleum hydrocarbons by heterotrophic bacteria ...

African Journals Online (AJOL)

Nitrogenous fertilizer (NPK) plant effluents from NAFCON were used in amending plots of land experimentally polluted with crude oil. Counts of heterotrophic bacteria (THBC) and fungi (TF), and of petroleum utilizing bacteria (PUB) and fungi (PUF) were monitored during an 8 weeks period. Counts obtained showed that ...

Differential staining of bacteria: gram stain.

Science.gov (United States)

Moyes, Rita B; Reynolds, Jackie; Breakwell, Donald P

2009-11-01

In 1884, Hans Christian Gram, a Danish doctor, developed a differential staining technique that is still the cornerstone of bacterial identification and taxonomic division. This multistep, sequential staining protocol separates bacteria into four groups based on cell morphology and cell wall structure: Gram-positive cocci, Gram-negative cocci, Gram-positive rods, and Gram-negative rods. The Gram stain is useful for assessing bacterial contamination of tissue culture samples or for examining the Gram stain status and morphological features of bacteria isolated from mixed or isolated bacterial cultures. (c) 2009 by John Wiley & Sons, Inc.

Manufacture of Probiotic Bacteria

Science.gov (United States)

Muller, J. A.; Ross, R. P.; Fitzgerald, G. F.; Stanton, C.

Lactic acid bacteria (LAB) have been used for many years as natural biopreservatives in fermented foods. A small group of LAB are also believed to have beneficial health effects on the host, so called probiotic bacteria. Probiotics have emerged from the niche industry from Asia into European and American markets. Functional foods are one of the fastest growing markets today, with estimated growth to 20 billion dollars worldwide by 2010 (GIA, 2008). The increasing demand for probiotics and the new food markets where probiotics are introduced, challenges the industry to produce high quantities of probiotic cultures in a viable and stable form. Dried concentrated probiotic cultures are the most convenient form for incorporation into functional foods, given the ease of storage, handling and transport, especially for shelf-stable functional products. This chapter will discuss various aspects of the challenges associated with the manufacturing of probiotic cultures.

The impact of lactic acid bacteria on sourdough fermentation

Directory of Open Access Journals (Sweden)

Savić Dragiša S.

2005-01-01

Full Text Available The baking of sourdough breads represents one of the oldest biotechnological processes. Despite traditionality, sourdough bread has great potential because of its benefits. Sourdough is a mixture of flour and water that is dominated by a complex microflora composed of yeasts and lactic acid bacteria that are crucial in the preparation of bread dough. Lactic acid bacteria cause acidification by producing lactic acid that increases the shelf life of bread by preventing the growth of undesirable microorganisms and affects the nutritional value of bread by increasing the availability of minerals. In addition to these advantages, the use of sourdough fermentation also improves dough machinability, breadcrumb structure and the characteristic flavour of bread. Lactic acid bacteria in sourdough fermentation are well known representing both homofermentative and heterofermentative bacteria. They may originate from selected natural contaminants in the flour or from a starter culture containing one or more known species of lactic acid bacteria. Sourdough can be cultivated in bakeries or obtained from commercial suppliers. However, many bakeries in Europe still use spontaneously fermented sourdoughs, which have been kept metabolically active for decades by the addition of flour and water at regular intervals. The impact of lactic acid bacteria on sourdough fermentation and their influence on dough and bread quality was discussed on the basis of research and literature data.

Time related total lactic acid bacteria population diversity and ...

African Journals Online (AJOL)

user

2011-02-07

Feb 7, 2011 ... the diversity and dynamics of lactic acid bacteria (LAB) population in fresh ..... combining morphological, biochemical and molecular data are important for ..... acid bacteria from fermented maize (Kenkey) and their interactions.

Presence of Pathogenic Bacteria and Viruses in the Daycare Environment.

Science.gov (United States)

Ibfelt, Tobias; Engelund, Eva Hoy; Permin, Anders; Madsen, Jonas Stenløkke; Schultz, Anna Charlotte; Andersen, Leif Percival

2015-10-01

The number of children in daycare centers (DCCs) is rising. This increases exposure to microorganisms and infectious diseases. Little is known about which bacteria and viruses are present in the DCC environment and where they are located. In the study described in this article, the authors set out to determine the prevalence of pathogenic bacteria and viruses and to find the most contaminated fomites in DCCs. Fifteen locations in each DCC were sampled for bacteria, respiratory viruses, and gastrointestinal viruses. The locations were in the toilet, kitchen, and playroom areas and included nursery pillows, toys, and tables, among other things. Coliform bacteria were primarily found in the toilet and kitchen areas whereas nasopharyngeal bacteria were found mostly on toys and fabric surfaces in the playroom. Respiratory viruses were omnipresent in the DCC environment, especially on the toys.

Influence of Chicken Manure Fertilization on Antibiotic-Resistant Bacteria in Soil and the Endophytic Bacteria of Pakchoi

Directory of Open Access Journals (Sweden)

Qingxiang Yang

2016-06-01

Full Text Available Animal manure is commonly used as fertilizer for agricultural crops worldwide, even though it is believed to contribute to the spread of antibiotic resistance from animal intestines to the soil environment. However, it is unclear whether and how there is any impact of manure fertilization on populations and community structure of antibiotic-resistant endophytic bacteria (AREB in plant tissues. To investigate the effect of manure and organic fertilizer on endophytic bacterial communities, pot experiments were performed with pakchoi grown with the following treatments: (1 non-treated; (2 chicken manure-treated and (3 organic fertilizer-treated. Manure or organic fertilizer significantly increased the abundances of total cultivable endophytic bacteria (TCEB and AREB in pakchoi, and the effect of chicken manure was greater than that of organic fertilizer. Further, 16S rDNA sequencing and the phylogenetic analysis indicated that chicken manure or organic fertilizer application increased the populations of multiple antibiotic-resistant bacteria (MARB in soil and multiple antibiotic-resistant endophytic bacteria (MAREB in pakchoi. The identical multiple antibiotic-resistant bacterial populations detected in chicken manure, manure- or organic fertilizer-amended soil and the vegetable endophytic system were Brevundimonas diminuta, Brachybacterium sp. and Bordetella sp., suggesting that MARB from manure could enter and colonize the vegetable tissues through manure fertilization. The fact that some human pathogens with multiple antibiotic resistance were detected in harvested vegetables after growing in manure-amended soil demonstrated a potential threat to human health.

Bacteria versus selenium: A view from the inside out

Science.gov (United States)

Staicu, Lucian; Oremland, Ronald S.; Tobe, Ryuta; Mihara, Hisaaki

2017-01-01

Bacteria and selenium (Se) are closely interlinked as the element serves both essential nutrient requirements and energy generation functions. However, Se can also behave as a powerful toxicant for bacterial homeostasis. Conversely, bacteria play a tremendous role in the cycling of Se between different environmental compartments, and bacterial metabolism has been shown to participate to all valence state transformations undergone by Se in nature. Bacteria possess an extensive molecular repertoire for Se metabolism. At the end of the 1980s, a novel mode of anaerobic respiration based on Se oxyanions was experimentally documented for the first time. Following this discovery, specific enzymes capable of reducing Se oxyanions and harvesting energy were found in a number of anaerobic bacteria. The genes involved in the expression of these enzymes have later been identified and cloned. This iterative approach undertaken outside-in led to the understanding of the molecular mechanisms of Se transformations in bacteria. Based on the extensive knowledge accumulated over the years, we now have a full(er) view from the inside out, from DNA-encoding genes to enzymes and thermodynamics. Bacterial transformations of Se for assimilatory purposes have been the object of numerous studies predating the investigation of Se respiration. Remarkable contributions related to the understating of the molecular picture underlying seleno-amino acid biosynthesis are reviewed herein. Under certain circumstances, Se is a toxicant for bacterial metabolism and bacteria have evolved strategies to counteract this toxicity, most notably by the formation of elemental Se (nano)particles. Several biotechnological applications, such as the production of functional materials and the biofortification of crop species using Se-utilizing bacteria, are presented in this chapter.

Isolation and Characterization of Lactic Acid Bacteria from Inasua

Directory of Open Access Journals (Sweden)

Ferymon Mahulette

2017-04-01

Full Text Available Inasua is a traditionally product of wet salt fish fermentation produced by Teon, Nila and Serua (TNS Communities in Central Maluku, Indonesia. The community made this fermented fish to anticipate the lean time when fisherman could not go to sea.  The  fish that used as inasua raw material is demersal fishes that live around coral reefs, such as Samandar fish (Siganatus guttatus, Gala-gala fish (Lutjanus sp. and Sikuda fish (Lethrinus ornatus. The objective of the research was to isolate and characterize of bacterial indigenous in  Inasua from three producers in Seram Island. The measurement of pH from inasua samples were 5.9, 5.0 and 5.8, respectively. The highest number of lactic acid bacteria was found from  Gala – gala inasua was 2,5x107 cfu/g sample. Isolation of all isolates bacteria from inasua showed that a total of 7 isolates of bacteria was obtained  from Samadar inasua, 9 isolates from  Gala-gala inasua, and 7 isolates from  Sikuda inasua.  From a total of 23 isolates, only 6 isolates had characteristic as lactic acid bacteria that were Gram  positive, negative catalase, and cocci shape. The microscopic characteristics  of the isolates are coccid in pairs or uniforms which combine to form tetrads. Carbohydrate utilization test  of selected isolate by using API 50 CHB kit indicated that 13 carbohydrates are fermented by these isolates  after incubation for 48 hours. The research  was concluded that the dominant bacteria in inasua sample  is  cocci-lactic acid bacteria. Keywords : fermented fish, inasua, lactic acid bacteria, MRSA medium

AIDS: "it's the bacteria, stupid!".

Science.gov (United States)

Broxmeyer, Lawrence; Cantwell, Alan

2008-11-01

Acid-fast tuberculous mycobacterial infections are common in AIDS and are regarded as secondary "opportunistic infections." According to the National Institute of Allergy and Infectious Diseases, TB is the major attributable cause of death in AIDS patients. Could such bacteria play a primary or causative role in AIDS? Certainly, In screening tests for HIV, there is frequent, up to 70%, cross-reactivity, between the gag and pol proteins of HIV and patients with mycobacterial infections such as tuberculosis. By 1972, five years before gays started dying in the U.S., Rolland wrote Genital Tuberculosis, a Forgotten Disease? And ironically, in 1979, on the eve of AIDS recognition, Gondzik and Jasiewicz showed that even in the laboratory, genitally infected tubercular male guinea pigs could infect healthy females through their semen by an HIV-compatible ratio of 1 in 6 or 17%, prompting him to warn his patients that not only was tuberculosis a sexually transmitted disease, but also the necessity of the application of suitable contraceptives, such as condoms, to avoid it. Gondzik's solution and date of publication are chilling; his findings significant. Since 1982 Cantwell et al found acid-fast bacteria closely related to tuberculosis (TB) and atypical tuberculosis in AIDS tissue. On the other hand molecular biologist and virologist Duesberg, who originally defined retroviral ultrastructure, has made it clear that HIV is not the cause of AIDS and that the so-called AIDS retrovirus has never been isolated in its pure state. Dr. Etienne de Harven, first to examine retroviruses under the electron, agrees. In 1993 HIV co-discoverer Luc Montagnier reported on cell-wall-deficient (CWD) bacteria which he called "mycoplasma" in AIDS tissue. He suspected these as a necessary "co-factor" for AIDS. Remarkably, Montagnier remained silent on Cantwell's reports of acid-fast bacteria which could simulate "mycoplasma" in AIDS tissue. Mattman makes clear that the differentiation between

Molecular genetic studies on obligate anaerobic bacteria

International Nuclear Information System (INIS)

Woods, D.R.

1982-01-01

Molecular genetic studies on obligate anaerobic bacteria have lagged behind similar studies in aerobes. However, the current interest in biotechnology, the involvement of anaerobes in disease and the emergence of antibioticresistant strains have focused attention on the genetics of anaerobes. This article reviews molecular genetic studies in Bacteroides spp., Clostridium spp. and methanogens. Certain genetic systems in some anaerobes differ from those in aerobes and illustrate the genetic diversity among bacteria

Effect of Ionizing Radiation on Luminous Bacteria Cells

International Nuclear Information System (INIS)

Kudryasheva, N.; Rozhko, T.; Alexandrova, M.; Vasyunkina, E.; Arkhipova, V.

2011-01-01

Marine luminous bacteria were used to monitor toxicity of alpha- (Am-241, U-235+238) and beta- (tritium) radionuclide solutions. Increase or inhibition of bacterial luminescence was observed under exposure to radionuclides. Radiation toxicity of Am and chemical toxicity of U were demonstrated. Effects of U were similar to those of stable heavy metals: sensitivity was about 10-5 M. Sensitivity of the bacteria to Am-241 was 300 Bq/L (10 -11 M). Inhibition of bacterial growth was observed under exposure to Am-241 and tritium. Role of peroxides and electron transfer processes in the effects of radionuclides on luminous bacteria is discussed.

An ancient divergence among the bacteria. [methanogenic phylogeny

Science.gov (United States)

Balch, W. E.; Magrum, L. J.; Fox, G. E.; Wolfe, R. S.; Woese, C. R.

1977-01-01

The 16S ribosomal RNZs from two species of met methanogenic bacteria, the mesophile Methanobacterium ruminantium and the thermophile Methanobacterium thermoautotrophicum, have been characterized in terms of the oligonucleotides produced by digestion with T1 ribonuclease. These two organisms are found to be sufficiently related that they can be considered members of the same genus or family. However, they bear only slight resemblance to 'typical' Procaryotic genera; such as Escherichia, Bacillus and Anacystis. The divergence of the methanogenic bacteria from other bacteria may be the most ancient phylogenetic event yet detected - antedating considerably the divergence of the blue green algal line for example, from the main bacterial line.

Legionella bacteria in combustion air humidifiers; Legionella i luftuppfuktare foer foerbraenningsluft

Energy Technology Data Exchange (ETDEWEB)

Jeppesen, Jessica; Hansson, Helen; Cederfeldt, Ola; Axby, Fredrik

2007-10-15

Over the last couple of years several outbreaks of Legionnaires' disease has occurred around the world. The source of infection varies, but in many cases the bacteria has been traced back to cooling towers. The common denominator for most of the sources of infection has been water systems with high oxygen levels and a system temperature ranging from 20 to 40 deg C. If a water system furthermore has high levels of other bacteria/microorganisms, then it is also probable that favorable conditions for legionella bacteria exist within the system. These conditions consist well with conditions in combustion air humidifiers in district heating plants and therefore it can be suspected that legionella may thrive also in these types of air humidifiers. In order to examine if legionella bacteria exists in combustion air humidifiers, and in what quantity, ten different district heating plants where selected for a survey. The goal of the survey is to get a general picture of the extent of the occurrence of legionella bacteria in different types of air humidifiers. This was done by taking legionella tests in three different types of air humidifiers in district heating plants. The first step of the testing was conducted by measuring the level of legionella bacteria in water samples from the air humidifiers in the different plants. The water samples were taken from water that circulates in the air humidifiers. A few months later another water sample was taken from the same location. Two district heating plants, where legionella bacteria had been detected, were selected for further testing after compiling the results from the first two tests. The further testing involved fuel gas analysis to see if any of the plants fuel gas contained legionella bacteria. The test results show that a major part of the district heating plants in the survey have heterotrophic bacteria in their water systems, which implies the possibility of growth of legionella bacteria. About half of the plants

9th International Symposium on Lactic Acid Bacteria

NARCIS (Netherlands)

Kuipers, Oscar P.; Poolman, Berend; Hugenholtz, Jeroen

What’s new in the field of lactic acid bacteria? The 9th International Symposium on Lactic Acid Bacteria (LAB9) will take place 31 August to 4 September 2008 in Egmond aan Zee, The Netherlands. Traditionally, the triannual LAB symposium focuses on the themes of genetics, physiology, and applications

Bacteriocins and lactic acid bacteria - a minireview | Savadogo ...

African Journals Online (AJOL)

Fermentation of various foods by lactic acid bacteria (LAB) is one of the oldest forms of biopreservation practised by mankind. Bacterial antagonism has been recognized for over a century but in recent years this phenomenon has received more scientific attention, particulary in the use of various strains of lactic acid bacteria.

Impacts of Gut Bacteria on Human Health and Diseases

Science.gov (United States)

Zhang, Yu-Jie; Li, Sha; Gan, Ren-You; Zhou, Tong; Xu, Dong-Ping; Li, Hua-Bin

2015-01-01

Gut bacteria are an important component of the microbiota ecosystem in the human gut, which is colonized by 1014 microbes, ten times more than the human cells. Gut bacteria play an important role in human health, such as supplying essential nutrients, synthesizing vitamin K, aiding in the digestion of cellulose, and promoting angiogenesis and enteric nerve function. However, they can also be potentially harmful due to the change of their composition when the gut ecosystem undergoes abnormal changes in the light of the use of antibiotics, illness, stress, aging, bad dietary habits, and lifestyle. Dysbiosis of the gut bacteria communities can cause many chronic diseases, such as inflammatory bowel disease, obesity, cancer, and autism. This review summarizes and discusses the roles and potential mechanisms of gut bacteria in human health and diseases. PMID:25849657

New Insight on the Response of Bacteria to Fluoride

Science.gov (United States)

Breaker, R.R.

2012-01-01

Fluoride has been used for decades to prevent caries and it is well established that this anion can inhibit the growth of bacteria. However, the precise effects that fluoride has on bacteria and the mechanisms that bacteria use to overcome fluoride toxicity have largely remained unexplored. Recently, my laboratory reported the discovery of biological systems that bacteria use to sense fluoride and reduce fluoride toxicity. These sensors and their associated genes are very widespread in biology, which has implications for a number of issues that are central to the use of fluoride for dental care. Below I provide a summary of our findings, comment on some of the key prospects for expanding our understanding of fluoride's effects on biology, and propose some future uses of this knowledge. PMID:22327376

New insight on the response of bacteria to fluoride.

Science.gov (United States)

Breaker, R R

2012-01-01

Fluoride has been used for decades to prevent caries and it is well established that this anion can inhibit the growth of bacteria. However, the precise effects that fluoride has on bacteria and the mechanisms that bacteria use to overcome fluoride toxicity have largely remained unexplored. Recently, my laboratory reported the discovery of biological systems that bacteria use to sense fluoride and reduce fluoride toxicity. These sensors and their associated genes are very widespread in biology, which has implications for a number of issues that are central to the use of fluoride for dental care. Below I provide a summary of our findings, comment on some of the key prospects for expanding our understanding of fluoride's effects on biology, and propose some future uses of this knowledge. Copyright © 2012 S. Karger AG, Basel.

Transfer of antibiotic resistant bacteria from animals to man

DEFF Research Database (Denmark)

Wegener, Henrik Caspar; Aarestrup, Frank Møller; Gerner-Smidt, P.

1999-01-01

for animals either for therapy or for growth promotion. Antibiotic resistance in zoonotic bacteria constitute a public health hazard, primarily through the increased risk of treatment failures. This paper describes the zoonotic bacteria, salmonella, campylobacter, yersinia and enterohaemorrhagic E. coli (EHEC......Antibiotic resistance develops in zoonotic bacteria in response to antibiotics used in food animals. A close association exists between the amounts of antibiotics used and the levels of resistance observed. The classes of antibiotics routinely used for treatment of human infections are also used......). Infections with these agents do not generally require antibiotic therapy, but in some cases antibiotics are essential to obtain a successful cure. The levels and types of resistance observed in zoonotic bacteria in some countries, especially the increasing levels of fluoroquinolone resistance in salmonella...

Algae-bacteria interactions: Evolution, ecology and emerging applications.

Science.gov (United States)

Ramanan, Rishiram; Kim, Byung-Hyuk; Cho, Dae-Hyun; Oh, Hee-Mock; Kim, Hee-Sik

2016-01-01

Algae and bacteria have coexisted ever since the early stages of evolution. This coevolution has revolutionized life on earth in many aspects. Algae and bacteria together influence ecosystems as varied as deep seas to lichens and represent all conceivable modes of interactions - from mutualism to parasitism. Several studies have shown that algae and bacteria synergistically affect each other's physiology and metabolism, a classic case being algae-roseobacter interaction. These interactions are ubiquitous and define the primary productivity in most ecosystems. In recent years, algae have received much attention for industrial exploitation but their interaction with bacteria is often considered a contamination during commercialization. A few recent studies have shown that bacteria not only enhance algal growth but also help in flocculation, both essential processes in algal biotechnology. Hence, there is a need to understand these interactions from an evolutionary and ecological standpoint, and integrate this understanding for industrial use. Here we reflect on the diversity of such relationships and their associated mechanisms, as well as the habitats that they mutually influence. This review also outlines the role of these interactions in key evolutionary events such as endosymbiosis, besides their ecological role in biogeochemical cycles. Finally, we focus on extending such studies on algal-bacterial interactions to various environmental and bio-technological applications. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Mechanistic modeling of biocorrosion caused by biofilms of sulfate reducing bacteria and acid producing bacteria.

Science.gov (United States)

Xu, Dake; Li, Yingchao; Gu, Tingyue

2016-08-01

Biocorrosion is also known as microbiologically influenced corrosion (MIC). Most anaerobic MIC cases can be classified into two major types. Type I MIC involves non-oxygen oxidants such as sulfate and nitrate that require biocatalysis for their reduction in the cytoplasm of microbes such as sulfate reducing bacteria (SRB) and nitrate reducing bacteria (NRB). This means that the extracellular electrons from the oxidation of metal such as iron must be transported across cell walls into the cytoplasm. Type II MIC involves oxidants such as protons that are secreted by microbes such as acid producing bacteria (APB). The biofilms in this case supply the locally high concentrations of oxidants that are corrosive without biocatalysis. This work describes a mechanistic model that is based on the biocatalytic cathodic sulfate reduction (BCSR) theory. The model utilizes charge transfer and mass transfer concepts to describe the SRB biocorrosion process. The model also includes a mechanism to describe APB attack based on the local acidic pH at a pit bottom. A pitting prediction software package has been created based on the mechanisms. It predicts long-term pitting rates and worst-case scenarios after calibration using SRB short-term pit depth data. Various parameters can be investigated through computer simulation. Copyright © 2016 Elsevier B.V. All rights reserved.

The seaweed holobiont: understanding seaweed-bacteria interactions.

Science.gov (United States)

Egan, Suhelen; Harder, Tilmann; Burke, Catherine; Steinberg, Peter; Kjelleberg, Staffan; Thomas, Torsten

2013-05-01

Seaweeds (macroalgae) form a diverse and ubiquitous group of photosynthetic organisms that play an essential role in aquatic ecosystems. These ecosystem engineers contribute significantly to global primary production and are the major habitat formers on rocky shores in temperate waters, providing food and shelter for aquatic life. Like other eukaryotic organisms, macroalgae harbor a rich diversity of associated microorganisms with functions related to host health and defense. In particular, epiphytic bacterial communities have been reported as essential for normal morphological development of the algal host, and bacteria with antifouling properties are thought to protect chemically undefended macroalgae from detrimental, secondary colonization by other microscopic and macroscopic epibiota. This tight relationship suggests that macroalgae and epiphytic bacteria interact as a unified functional entity or holobiont, analogous to the previously suggested relationship in corals. Moreover, given that the impact of diseases in marine ecosystems is apparently increasing, understanding the role of bacteria as saprophytes and pathogens in seaweed communities may have important implications for marine management strategies. This review reports on the recent advances in the understanding of macroalgal-bacterial interactions with reference to the diversity and functional role of epiphytic bacteria in maintaining algal health, highlighting the holobiont concept. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Working with bacteria and putting bacteria to work: The biopolitics of synthetic biology for energy in the United Kingdom

OpenAIRE

McLeod, Carmen; Nerlich, Brigitte; Mohr, Alison

2017-01-01

The UK government has made significant investment into so called ‘fourth-generation’ biofuel technologies. These biofuels are based on engineering the metabolic pathways of bacteria in order to create products compatible with existing infrastructure. Bacteria play an important role in what is promoted as a potentially new biological industrial revolution, which could address some of the negative environmental legacies of the last. This article presents results from ethnographic research with ...

Glass bead transformation method for gram-positive bacteria

OpenAIRE

Rattanachaikunsopon, Pongsak; Phumkhachorn, Parichat

2009-01-01

A simple, inexpensive and reproducible transformation method was developed for Gram-positive bacteria. It was based on agitation of bacterial protoplasts with glass beads in the presence of DNA and polyethylene glycol. By using this method, introduction of pGK12 into protoplasts of several strains of Gram-positive bacteria was achieved.

The bacteriological safety and antimicrobial susceptibility of bacteria ...

African Journals Online (AJOL)

In developing countries the major sources of food-borne illnesses are street vended foods. The aim of this study was thus to assess the prevalence and antibiogram of bacteria from white lupin in Bahir Dar Town. METHODS: A total of 40 samples were processed for detection of indicator bacteria and pathogens from ...

Hydrodynamic interaction between bacteria and passive sphere

Science.gov (United States)

Zhang, Bokai; Ding, Yang; Xu, Xinliang

2017-11-01

Understanding hydrodynamic interaction between bacteria and passive sphere is important for identifying rheological properties of bacterial and colloidal suspension. Over the past few years, scientists mainly focused on bacterial influences on tracer particle diffusion or hydrodynamic capture of a bacteria around stationary boundary. Here, we use superposition of singularities and regularized method to study changes in bacterial swimming velocity and passive sphere diffusion, simultaneously. On this basis, we present a simple two-bead model that gives a unified interpretation of passive sphere diffusion and bacterial swimming. The model attributes both variation of passive sphere diffusion and changes of speed of bacteria to an effective mobility. Using the effective mobility of bacterial head and tail as an input function, the calculations are consistent with simulation results at a broad range of tracer diameters, incident angles and bacterial shapes.

Bacteria in non-woven textile filters for domestic wastewater treatment.

Science.gov (United States)

Spychała, Marcin; Starzyk, Justyna

2015-01-01

The objective of this study was preliminary identification of heterotrophic and ammonia oxidizing bacteria (AOB) cell concentration in the cross-sectional profile of geotextile filters for wastewater treatment. Filters of thicknesses 3.6 and 7.2 mm, made of non-woven textile TS20, were supplied with septic tank effluent and intermittently dosed and filtered under hydrostatic pressure. The cumulative loads of chemical oxygen demand (COD) and total solids were about 1.36 and 1.06 kg/cm2, respectively. The filters under analysis reached a relatively high removal efficiency for organic pollution 70-90% for biochemical oxygen demand (BOD5) and 60-85% for COD. The ammonia nitrogen removal efficiency level proved to be unstable (15-55%). Biomass samples for dry mass identification were taken from two regions: continuously flooded with wastewater and intermittently flooded with wastewater. The culturable heterotrophic bacteria were determined as colony-forming units (CFUs) on microbiological-selective media by means of the plate method. AOB and nitrite oxidizing bacteria (NOB) were examined using the FISH technique. A relatively wide range of heterotrophic bacteria was observed from 7.4×10(5)/cm2 to 3.8×10(6)/cm2 in geotextile layers. The highest concentration of heterotrophic bacteria (3.8×10(6)/cm2) was observed in the first layer of the textile filter. AOB were identified occasionally--about 8-15% of all bacteria colonizing the last filter layer, but occasionally much higher concentrations and ammonia nitrogen efficiency were achieved. Bacteria oxidizing nitrite to nitrate were not observed. The relation of total and organic fraction of biomass to culturable heterotrophic bacteria was also found.

Anaerobic sulfide-oxidation in marine colorless sulfur-oxidizing bacteria

Digital Repository Service at National Institute of Oceanography (India)

LokaBharathi, P.A.; Nair, S.; Chandramohan, D.

Colorless sulfur-oxidizing bacteria are ubiquitous in Indian waters and have the ability to oxidize sulfide under anaerobic conditions. These bacteria can not only mediate the sulfur cycle oxidatively but also the nitrogen cycle reductively without...

Marine Bacteria from Eastern Indonesia Waters and Their Potential Use in Biotechnology

Directory of Open Access Journals (Sweden)

Yosmina H Tapilatu

2016-05-01

Full Text Available Indonesian vast marine waters, which constitute 81% of the country’s total area, have a great potential in terms of marine bacteria biodiversity. However, marine bacteria are still under-explored in Indonesia, especially in its eastern area. Known as one of the biodiversity hotspots worldwide, this area surely harbors various marine bacteria of particular interest. Despite the growing number of oceanic expeditions carried out in this area, only little attention has been attributed to marine bacteria. Limited literatures exist on the isolation of marine bacteria producing compounds with potential biotechnological applications from the aforementioned waters. There are two main causes of this problem, namely lack of infrastructures and limited competent human resources. In this paper, I will highlight the preliminary results of isolation and bioprospecting attempts on this group of bacteria during the last fifteen years. These results indicate that research activities on marine bacteria in this area need to be intensified, to uncover their potential applications in various biotechnological fields. Keywords: marine bacteria, eastern Indonesian waters, biotechnological application

Bacterial spot and early blight biocontrol by epiphytic bacteria in tomato plants

Directory of Open Access Journals (Sweden)

Roberto Lanna Filho

2010-12-01

Full Text Available The objective of this work was to evaluate in vitro and in vivo biocontrol of bacterial spot (Xanthomonas vesicatoria and early blight (Alternaria solani by the epiphytic bacteria Paenibacillus macerans and Bacillus pumilus. Tomato plants were previously sprayed with epiphytic bacteria, benzalkonium chloride and PBS buffer and, after four days, they were inoculated with A. solani and X. vesicatoria. To determine the phytopathogenic bacteria population, leaflet samples were collected from each treatment every 24 hours, for seven days, and plated on semi-selective medium. The effect of epiphytic bacteria over phytopathogens was performed by the antibiosis test and antagonistic activity measured by inhibition zone diameter. The epiphytic and benzalkonium chloride drastically reduced the severity of early blight and bacterial spot in comparison to the control (PBS. In detached leaflets, the epiphytic bacteria reduced in 70% the number of phytopathogenic bacteria cells in the phylloplane. The antibiosis test showed that the epiphytic bacteria efficiently inhibit the phytopathogens growth. In all the bioassays, the epiphytic bacteria protect tomato plants against the phytopathogens

The role of bacteria and mycorrhiza in plant sulfur supply

Directory of Open Access Journals (Sweden)

Jacinta Mariea Gahan

2014-12-01

Full Text Available Plant growth is highly dependent on bacteria, saprophytic and mycorrhizal fungi which facilitate the cycling and mobilization of nutrients. Over 95% of the sulfur (S in soil is present in an organic form. Sulfate-esters and sulfonates, the major forms of organo-S in soils, arise through deposition of biological material and are transformed through subsequent humification. Fungi and bacteria release S from sulfate-esters using sulfatases, however, release of S from sulfonates is catalyzed by a bacterial multi-component mono-oxygenase system. The asfA gene is used as a key marker in this desulfonation process to study sulfonatase activity in soil bacteria identified as Variovorax, Polaromonas, Acidovorax and Rhodococcus. The rhizosphere is regarded as a hot spot for microbial activity and recent studies indicate that this is also the case for the mycorrhizosphere where bacteria may attach to the fungal hyphae capable of mobilizing organo-S. While current evidence is not showing sulfatase and sulfonatase activity in arbuscular mycorrhiza, their effect on the expression of plant host sulfate transporters is documented. A revision of the role of bacteria, fungi and the interactions between soil bacteria and mycorrhiza in plant S supply was conducted.

[Experimental interaction of halophilic prokaryotes and opportunistic bacteria in brine].

Science.gov (United States)

Selivanova, E A; Nemtseva, N V

2013-01-01

Study the effect of extremely halophilic archaea and moderately halophilic bacteria on preservation of opportunistic bacteria in brine. 17 strains of moderately halophilic bacteria and 2 strains of extremely halophilic archaea were isolated from continental hypersaline lake Razval of Sol-Iletsk area of Orenburg Region. Identification of pure cultures of prokaryotes was carried out taking into account their phenotype properties and based on determination of 16S RNA gene sequence. The effect of halophilic prokaryote on elimination of Escherichia coli from brine was evaluated during co-cultivation. Antagonistic activity of cell extracts of the studied microorganisms was evaluated by photometric method. A more prolonged preservation of an E. coli strain in brine in the presence of live cells of extremely halophilic archaea Halorubrum tebenquichense and moderately halophilic bacteria Marinococcus halophilus was established. Extracts of cells of extremely halophilic archaea and moderately halophilic bacteria on the contrary displayed antagonistic activity. The protective effect of live cells of halophilic prokaryotes and antagonistic activity of their cell extracts change the period of conservation of opportunistic bacteria in brine that regulates inter-microbial interactions and changes the period of self-purification that reflects the sanitary condition of a hypersaline water body.

Natural soil reservoirs for human pathogenic and fecal indicator bacteria

Science.gov (United States)

Boschiroli, Maria L; Falkinham, Joseph; Favre-Bonte, Sabine; Nazaret, Sylvie; Piveteau, Pascal; Sadowsky, Michael J.; Byappanahalli, Muruleedhara; Delaquis, Pascal; Hartmann, Alain

2016-01-01

Soils receive inputs of human pathogenic and indicator bacteria through land application of animal manures or sewage sludge, and inputs by wildlife. Soil is an extremely heterogeneous substrate and contains meso- and macrofauna that may be reservoirs for bacteria of human health concern. The ability to detect and quantify bacteria of human health concern is important in risk assessments and in evaluating the efficacy of agricultural soil management practices that are protective of crop quality and protective of adjacent water resources. The present chapter describes the distribution of selected Gram-positive and Gram-negative bacteria in soils. Methods for detecting and quantifying soilborne bacteria including extraction, enrichment using immunomagnetic capture, culturing, molecular detection and deep sequencing of metagenomic DNA to detect pathogens are overviewed. Methods for strain phenotypic and genotypic characterization are presented, as well as how comparison with clinical isolates can inform the potential for human health risk.

Influence of disturbances on bacteria level in an operating room

DEFF Research Database (Denmark)

Brohus, Henrik; Hyldig, Mikkel; Kamper, Simon

2008-01-01

In operating rooms great effort is manifested to reduce the bacteria level in order to decrease the risk of infections. The main source of bacteria is the staff and the patient, thus, the resulting bacteria concentration is roughly speaking a combination of the ventilation system and the emission...... from the occupants. This study investigates the influence of two main disturbances in an operating room namely the door opening during the operation and the activity level of the staff. It is found that the frequent door opening in this case does not cause significant transport of air from outside...... the operating room to the wound area of the patient. However, a significant influence of the activity level on the bacteria emission and concentration is found. Counting the number of persons in an operating room to estimate the bacteria source strength is not sufficient, the corresponding activity level must...

An efficient method for qualitative screening of phosphate-solubilizing bacteria.

Science.gov (United States)

Mehta, S; Nautiyal, C S

2001-07-01

An efficient protocol was developed for qualitative screening of phosphate-solubilizing bacteria, based upon visual observation. Our results indicate that, by using our formulation containing bromophenol blue, it is possible to quickly screen on a qualitative basis the phosphate-solubilizing bacteria. Qualitative analysis of the phosphate solubilized by various groups correlated well with grouping based upon quantitative analysis of bacteria isolated from soil, effect of carbon, nitrogen, salts, and phosphate solubilization-defective transposon mutants. However, unlike quantitative analysis methods that involve time-consuming biochemical procedures, the time for screening phosphate-solubilizing bacteria is significantly reduced by using our simple protocol. Therefore, it is envisaged that usage of this formulation based upon qualitative analysis will be salutary for the quick screening of phosphate-solubilizing bacteria. Our results indicate that the formulation can also be used as a quality control test for expeditiously screening the commercial bioinoculant preparations, based on phosphate solubilizers.

Conspicuous veils formed by vibrioid bacteria on sulfidic marine sediment

DEFF Research Database (Denmark)

Thar, Roland Matthias; Kühl, Michael

2002-01-01

, but the bacteria have so far not been isolated in pure culture, and a detailed characterization of their metabolism is still lacking. The bacteria are colorless, gram-negative, and vibrioid-shaped (1.3- to 2.5- by 4- to 10-µm) cells that multiply by binary division and contain several spherical inclusions of poly......We describe the morphology and behavior of a hitherto unknown bacterial species that forms conspicuous veils (typical dimensions, 30 by 30 mm) on sulfidic marine sediment. The new bacteria were enriched on complex sulfidic medium within a benthic gradient chamber in oxygen-sulfide countergradients......, forming a cohesive whitish veil at the oxic-anoxic interface. Bacteria attached to the veil kept rotating and adapted their stalk lengths dynamically to changing oxygen concentrations. The joint action of rotating bacteria on the veil induced a homogeneous water flow from the oxic water region toward...

Ecology: Electrical Cable Bacteria Save Marine Life

DEFF Research Database (Denmark)

Nielsen, Lars Peter

2016-01-01

Animals at the bottom of the sea survive oxygen depletion surprisingly often, and a new study identifies cable bacteria in the sediment as the saviors. The bacterial electrical activity creates an iron 'carpet', trapping toxic hydrogen sulfide.......Animals at the bottom of the sea survive oxygen depletion surprisingly often, and a new study identifies cable bacteria in the sediment as the saviors. The bacterial electrical activity creates an iron 'carpet', trapping toxic hydrogen sulfide....

Occurrence of diazotrophic bacteria in Araucaria angustifolia

OpenAIRE

Neroni,Rafaela de Fátima; Cardoso,Elke Jurandy Bran Nogueira

2007-01-01

Araucaria angustifolia is an environmentally threatened tree and the whole biota of the Araucaria Forest should be investigated with the aim of its preservation. Diazotrophic bacteria are extremely important for the maintenance of ecosystems, but they have never been studied in Araucaria Forests. In this study, diazotrophic bacteria were isolated from Araucaria roots and soil, when grown in semi-specific, semi-solid media. The diazotrophic character of some recovered isolates could be confirm...

Tumour targeting with systemically administered bacteria.

LENUS (Irish Health Repository)

Morrissey, David

2012-01-31

Challenges for oncology practitioners and researchers include specific treatment and detection of tumours. The ideal anti-cancer therapy would selectively eradicate tumour cells, whilst minimising side effects to normal tissue. Bacteria have emerged as biological gene vectors with natural tumour specificity, capable of homing to tumours and replicating locally to high levels when systemically administered. This property enables targeting of both the primary tumour and secondary metastases. In the case of invasive pathogenic species, this targeting strategy can be used to deliver genes intracellularly for tumour cell expression, while non-invasive species transformed with plasmids suitable for bacterial expression of heterologous genes can secrete therapeutic proteins locally within the tumour environment (cell therapy approach). Many bacterial genera have been demonstrated to localise to and replicate to high levels within tumour tissue when intravenously (IV) administered in rodent models and reporter gene tagging of bacteria has permitted real-time visualisation of this phenomenon. Live imaging of tumour colonising bacteria also presents diagnostic potential for this approach. The nature of tumour selective bacterial colonisation appears to be tumour origin- and bacterial species- independent. While originally a correlation was drawn between anaerobic bacterial colonisation and the hypoxic nature of solid tumours, it is recently becoming apparent that other elements of the unique microenvironment within solid tumours, including aberrant neovasculature and local immune suppression, may be responsible. Here, we consider the pre-clinical data supporting the use of bacteria as a tumour-targeting tool, recent advances in the area, and future work required to develop it into a beneficial clinical tool.

Radiographic markers - A reservoir for bacteria?

International Nuclear Information System (INIS)

Tugwell, Jenna; Maddison, Adele

2011-01-01

Introduction: Amongst the most frequently handled objects in the radiology department are radiographic markers. They are personal accessories used with every patient, and are kept in the radiographers pockets when not utilised. Upon enquiry it was discovered that many radiographers disregarded the potential of these accessories to become a vector for cross-contamination thus never or rarely clean them. The aims of this study were therefore to identify if radiographic markers are a reservoir for bacteria and to establish an effective cleaning method for decontaminating them. Methodology: 25 radiographers/student radiographers were selected for this study. Swabbing of their markers prior and post cleaning took place. The microbiology laboratory subsequently analyzed the results by quantifying and identifying the bacteria present. The participants also completed a closed questionnaire regarding their markers (e.g. frequency of cleaning and type of marker) to help specify the results gained from the swabbing procedure. Results: From the sample swabbed, 92% were contaminated with various organisms including Staphylococcus and Bacillus species, the amount of bacteria present ranged from 0 to >50 CFU. There were no significant differences between disinfectant wipes and alcohol gel in decontaminating the markers. Both successfully reduced their bacterial load, with 80% of the markers post cleaning having 0 CFU. Conclusion: The results indicated that radiographic markers can become highly contaminated with various organisms thus serve as a reservoir for bacteria. In addition, the markers need to be cleaned on a regular basis, with either disinfectant wipes or alcohol gel to reduce their bacterial load.

Antimicrobial Photodynamic Therapy to Kill Gram-negative Bacteria

Science.gov (United States)

Sperandio, Felipe F; Huang, Ying-Ying; Hamblin, Michael R

2013-01-01

Antimicrobial photodynamic therapy (PDT) or photodynamic inactivation (PDI) is a new promising strategy to eradicate pathogenic microorganisms such as Gram-positive and Gram-negative bacteria, yeasts and fungi. The search for new approaches that can kill bacteria but do not induce the appearance of undesired drug-resistant strains suggests that PDT may have advantages over traditional antibiotic therapy. PDT is a non-thermal photochemical reaction that involves the simultaneous presence of visible light, oxygen and a dye or photosensitizer (PS). Several PS have been studied for their ability to bind to bacteria and efficiently generate reactive oxygen species (ROS) upon photostimulation. ROS are formed through type I or II mechanisms and may inactivate several classes of microbial cells including Gram-negative bacteria such as Pseudomonas aeruginosa, which are typically characterized by an impermeable outer cell membrane that contains endotoxins and blocks antibiotics, dyes, and detergents, protecting the sensitive inner membrane and cell wall. This review covers significant peer-reviewed articles together with US and World patents that were filed within the past few years and that relate to the eradication of Gram-negative bacteria via PDI or PDT. It is organized mainly according to the nature of the PS involved and includes natural or synthetic food dyes; cationic dyes such as methylene blue and toluidine blue; tetrapyrrole derivatives such as phthalocyanines, chlorins, porphyrins, chlorophyll and bacteriochlorophyll derivatives; functionalized fullerenes; nanoparticles combined with different PS; other formulations designed to target PS to bacteria; photoactive materials and surfaces; conjugates between PS and polycationic polymers or antibodies; and permeabilizing agents such as EDTA, PMNP and CaCl2. The present review also covers the different laboratory animal models normally used to treat Gram-negative bacterial infections with antimicrobial PDT. PMID

Bactericidal activity of bio-synthesized silver nanoparticles against human pathogenic bacteria

International Nuclear Information System (INIS)

Abalkhil, Tarad Abdulaziz; Alharbi, Sulaiman Ali; Salmen, Saleh Hussein; Wainwright, Milton

2017-01-01

Green synthesis is an attractive and eco-friendly approach to generate potent antibacterial silver nanoparticles (Ag-NPs). Such particles have long been used to fight bacteria and represent a promising tool to overcome the emergence of antibiotic-resistant bacteria. In this study, green synthesis of Ag-NPs was attempted using plant extracts of Aloe vera, Portulaca oleracea and Cynodon dactylon. The identity and size of Ag-NPs was characterized by ultraviolet–visible spectrophotometer and scanning electron microscopy. Monodispersed Ag-NPs were produced with a range of different sizes based on the plant extract used. The bactericidal activity of Ag-NPs against a number of human pathogenic bacteria was determined using the disc diffusion method. The results showed that Gram positive bacteria were more susceptible than Gram negative ones to these antibacterial agents. The minimum inhibitory concentration was determined using the 96- well plate method. Finally, the mechanism by which Ag-NPs affect bacteria was investigated by SEM analysis. Bacteria treated with Ag-NPs were seen to undergo shrinkage and to lose their viability. This study provides evidence for a cheap and effective method for synthesizing potent bactericidal Ag-NPs and demonstrates their effectiveness against human pathogenic bacteria

What Bacteria Are Living in My Food?: An Open-Ended Practical Series Involving Identification of Unknown Foodborne Bacteria Using Molecular Techniques

Science.gov (United States)

Prasad, Prascilla; Turner, Mark S.

2011-01-01

This open-ended practical series titled "Molecular Identification of Unknown Food Bacteria" which extended over a 6-week period was designed with the aims of giving students an opportunity to gain an understanding of naturally occurring food bacteria and skills in contemporary molecular methods using real food samples. The students first isolated…

Iron biomineralization by anaerobic neutrophilic iron-oxidizing bacteria

DEFF Research Database (Denmark)

Miot, Jennyfer; Benzerara, Karim; Morin, Guillaume

2009-01-01

Minerals formed by bio-oxidation of ferrous iron (Fe(II)) at neutral pH, their association with bacterial ultrastructures as well as their impact on the metabolism of iron-oxidizing bacteria remain poorly understood. Here, we investigated iron biomineralization by the anaerobic nitrate-dependent ......Minerals formed by bio-oxidation of ferrous iron (Fe(II)) at neutral pH, their association with bacterial ultrastructures as well as their impact on the metabolism of iron-oxidizing bacteria remain poorly understood. Here, we investigated iron biomineralization by the anaerobic nitrate...... precipitation in the periplasm (in a few tens of minutes), followed by the formation of surface-bound globules. Moreover, we frequently observed an asymmetric mineral thickening at the cell poles. In parallel, the evolution of iron oxidation was quantified by STXM: iron both contained in the bacteria...... and in the extracellular precipitates reached complete oxidation within 6 days. While a progressive oxidation of Fe in the bacteria and in the medium could be observed, spatial redox (oxido-reduction state) heterogeneities were detected at the cell poles and in the extracellular precipitates after 1 day. All...

Functional Encyclopedia of Bacteria and Archaea

Energy Technology Data Exchange (ETDEWEB)

Blow, M. J.; Deutschbauer, A. M.; Hoover, C. A.; Lamson, J.; Lamson, J.; Price, M. N.; Waters, J.; Wetmore, K. M.; Bristow, J.; Arkin, A. P.

2013-03-20

Bacteria and Archaea exhibit a huge diversity of metabolic capabilities with fundamental importance in the environment, and potential applications in biotechnology. However, the genetic bases of these capabilities remain unclear due largely to an absence of technologies that link DNA sequence to molecular function. To address this challenge, we are developing a pipeline for high throughput annotation of gene function using mutagenesis, growth assays and DNA sequencing. By applying this pipeline to annotate gene function in 50 diverse microbes we hope to discover thousands of new gene functions and produce a proof of principle `Functional Encyclopedia of Bacteria and Archaea?.

Applications of Magnetosomes Synthesized by Magnetotactic Bacteria in Medicine

International Nuclear Information System (INIS)

Alphandéry, Edouard

2014-01-01

Magnetotactic bacteria belong to a group of bacteria that synthesize iron oxide nanoparticles covered by biological material that are called magnetosomes. These bacteria use the magnetosomes as a compass to navigate in the direction of the earth’s magnetic field. This compass helps the bacteria to find the optimum conditions for their growth and survival. Here, we review several medical applications of magnetosomes, such as those in magnetic resonance imaging (MRI), magnetic hyperthermia, and drug delivery. Different methods that can be used to prepare the magnetosomes for these applications are described. The toxicity and biodistribution results that have been published are summarized. They show that the magnetosomes can safely be used provided that they are prepared in specific conditions. The advantageous properties of the magnetosomes compared with those of chemically synthesized nanoparticles of similar composition are also highlighted.

Differentiating the growth phases of single bacteria using Raman spectroscopy

Science.gov (United States)

Strola, S. A.; Marcoux, P. R.; Schultz, E.; Perenon, R.; Simon, A.-C.; Espagnon, I.; Allier, C. P.; Dinten, J.-M.

2014-03-01

In this paper we present a longitudinal study of bacteria metabolism performed with a novel Raman spectrometer system. Longitudinal study is possible with our Raman setup since the overall procedure to localize a single bacterium and collect a Raman spectrum lasts only 1 minute. Localization and detection of single bacteria are performed by means of lensfree imaging, whereas Raman signal (from 600 to 3200 cm-1) is collected into a prototype spectrometer that allows high light throughput (HTVS technology, Tornado Spectral System). Accomplishing time-lapse Raman spectrometry during growth of bacteria, we observed variation in the net intensities for some band groups, e.g. amides and proteins. The obtained results on two different bacteria species, i.e. Escherichia coli and Bacillus subtilis clearly indicate that growth affects the Raman chemical signature. We performed a first analysis to check spectral differences and similarities. It allows distinguishing between lag, exponential and stationary growth phases. And the assignment of interest bands to vibration modes of covalent bonds enables the monitoring of metabolic changes in bacteria caused by growth and aging. Following the spectra analysis, a SVM (support vector machine) classification of the different growth phases is presented. In sum this longitudinal study by means of a compact and low-cost Raman setup is a proof of principle for routine analysis of bacteria, in a real-time and non-destructive way. Real-time Raman studies on metabolism and viability of bacteria pave the way for future antibiotic susceptibility testing.

Immobilization of ammonia-oxidizing bacteria by polyvinyl alcohol and sodium alginate.

Science.gov (United States)

Dong, Yuwei; Zhang, Yanqiu; Tu, Baojun

Ammonia-oxidizing bacteria were immobilized by polyvinyl alcohol (PVA) and sodium alginate. The immobilization conditions and ammonia oxidation ability of the immobilized bacteria were investigated. The following immobilization conditions were observed to be optimal: PVA, 12%; sodium alginate, 1.1%; calcium chloride, 1.0%; inoculum concentration, 1.3 immobilized balls/mL of immobilized medium; pH, 10; and temperature, 30°C. The immobilized ammonia-oxidizing bacteria exhibited strong ammonia oxidation ability even after being recycled four times. The ammonia nitrogen removal rate of the immobilized ammonia-oxidizing bacteria reached 90.30% under the optimal immobilization conditions. When compared with ammonia-oxidizing bacteria immobilized by sodium alginate alone, the bacteria immobilized by PVA and sodium alginate were superior with respect to pH resistance, the number of reuses, material cost, heat resistance, and ammonia oxidation ability. Copyright © 2017 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

Novel anammox bacteria and nitrogen loss from Lake Superior

DEFF Research Database (Denmark)

Crowe, Sean A.; Treusch, Alexander H.; Forth, Michael

2017-01-01

and diversity of anammox bacteria in the world's largest freshwater lake - Lake Superior. We found that anammox performed by previously undiscovered bacteria is an important contributor to sediment N2 production. We observed striking differences in the anammox bacterial populations found at different locations...... within Lake Superior and those described from other locations. Our data thus reveal that novel anammox bacteria underpin N-loss from Lake Superior, and if more broadly distributed across inland waters would play an important role in continental N-cycling and mitigation of fixed nitrogen transfer from...

Physiology and genetics of sulfur-oxidizing bacteria.

Science.gov (United States)

Friedrich, C G

1998-01-01

Reduced inorganic sulfur compounds are oxidized by members of the domains Archaea and Bacteria. These compounds are used as electron donors for anaerobic phototrophic and aerobic chemotrophic growth, and are mostly oxidized to sulfate. Different enzymes mediate the conversion of various reduced sulfur compounds. Their physiological function in sulfur oxidation is considered (i) mostly from the biochemical characterization of the enzymatic reaction, (ii) rarely from the regulation of their formation, and (iii) only in a few cases from the mutational gene inactivation and characterization of the resulting mutant phenotype. In this review the sulfur-metabolizing reactions of selected phototrophic and of chemotrophic prokaryotes are discussed. These comprise an archaeon, a cyanobacterium, green sulfur bacteria, and selected phototrophic and chemotrophic proteobacteria. The genetic systems are summarized which are presently available for these organisms, and which can be used to study the molecular basis of their dissimilatory sulfur metabolism. Two groups of thiobacteria can be distinguished: those able to grow with tetrathionate and other reduced sulfur compounds, and those unable to do so. This distinction can be made irrespective of their phototrophic or chemotrophic metabolism, neutrophilic or acidophilic nature, and may indicate a mechanism different from that of thiosulfate oxidation. However, the core enzyme for tetrathionate oxidation has not been identified so far. Several phototrophic bacteria utilize hydrogen sulfide, which is considered to be oxidized by flavocytochrome c owing to its in vitro activity. However, the function of flavocytochrome c in vivo may be different, because it is missing in other hydrogen sulfide-oxidizing bacteria, but is present in most thiosulfate-oxidizing bacteria. A possible function of flavocytochrome c is discussed based on biophysical studies, and the identification of a flavocytochrome in the operon encoding enzymes involved

The Role of Plant Growth-Promoting Bacteria in Metal Phytoremediation.

Science.gov (United States)

Kong, Zhaoyu; Glick, Bernard R

2017-01-01

Phytoremediation is a promising technology that uses plants and their associated microbes to clean up contaminants from the environment. In recent years, phytoremediation assisted by plant growth-promoting bacteria (PGPB) has been highly touted for cleaning up toxic metals from soil. PGPB include rhizospheric bacteria, endophytic bacteria and the bacteria that facilitate phytoremediation by other means. This review provides information about the traits and mechanisms possessed by PGPB that improve plant metal tolerance and growth, and illustrate mechanisms responsible for plant metal accumulation/translocation in plants. Several recent examples of phytoremediation of metals facilitated by PGPB are reviewed. Although many encouraging results have been reported in the past years, there have also been numerous challenges encountered in phytoremediation in the field. To implement PGPB-assisted phytoremediation of metals in the natural environment, there is also a need to critically assess the ecological effects of PGPB, especially for those nonnative bacteria. © 2017 Elsevier Ltd All rights reserved.

Influencing factors analysis of anammox bacteria cultured by mixing denitrifying-anammox

OpenAIRE

Sihui WANG; Yuanyuan SONG; Yunman LIU; Yankai GUO; Jing LIAN; Jianbo GUO

2017-01-01

In order to get the optimal growth conditions of anammox bacteria, the mature-cultured anammox granule sludge is used to investigate the influencing factors. The effects of temperature, pH value, COD and influent substrate (NO-2-N and NH+4-N) on anammox bacteria activity are investigated. The results demonstrate that the optimal temperature is 40 ℃ and the optimal pH value is between 7.0~8.0 for anammox bacteria. The anammox bacteria activity is not inhibited severely when COD concentration i...

Carbon isotope fractionation by anoxygenic phototrophic bacteria in euxinic Lake Cadagno

DEFF Research Database (Denmark)

Posth, Nicole Rita Elisabeth; Bristow, L. A.; Cox, R. P.

2017-01-01

carbon (POC) in the Lake Cadagno chemocline. This large fractionation between the DIC and POC was also found in culture experiments carried out with anoxygenic phototrophic bacteria isolated from the lake. In the Lake Cadagno chemocline, anoxygenic phototrophic bacteria controlled the bulk C......Anoxygenic phototrophic bacteria utilize ancient metabolic pathways to link sulfur and iron metabolism to the reduction of CO2. In meromictic Lake Cadagno, Switzerland, both purple sulfur (PSB) and green sulfur anoxygenic phototrophic bacteria (GSB) dominate the chemocline community and drive...

Active oil-water interfaces: buckling and deformation of oil drops by bacteria

Science.gov (United States)

Juarez, Gabriel; Stocker, Roman

2014-11-01

Bacteria are unicellular organisms that seek nutrients and energy for growth, division, and self-propulsion. Bacteria are also natural colloidal particles that attach and self-assemble at liquid-liquid interfaces. Here, we present experimental results on active oil-water interfaces that spontaneously form when bacteria accumulate or grow on the interface. Using phase-contrast and fluorescence microscopy, we simultaneously observed the dynamics of adsorbed Alcanivorax bacteria and the oil-water interface within microfluidic devices. We find that, by growing and dividing, adsorbed bacteria form a jammed monolayer of cells that encapsulates the entire oil drop. As bacteria continue to grow at the interface, the drop buckles and the interface undergoes strong deformations. The bacteria act to stabilize non-equilibrium shapes of the oil-phase such wrinkling and tubulation. In addition to presenting a natural example of a living interface, these findings shape our understanding of microbial degradation of oil and may have important repercussions on engineering interventions for oil bioremediation.

Heme and menaquinone induced electron transport in lactic acid bacteria

OpenAIRE

Brooijmans, Rob; Smit, Bart; Santos, Filipe; van Riel, Jan; de Vos, Willem M; Hugenholtz, Jeroen

2009-01-01

Abstract Background For some lactic acid bacteria higher biomass production as a result of aerobic respiration has been reported upon supplementation with heme and menaquinone. In this report, we have studied a large number of species among lactic acid bacteria for the existence of this trait. Results Heme- (and menaquinone) stimulated aerobic growth was observed for several species and genera of lactic acid bacteria. These include Lactobacillus plantarum, Lactobacillus rhamnosus, Lactobacill...

PENAMBAHAN BAKTERI ASAM LAKTAT TERENKAPSULASI UNTUK MENEKAN PERTUMBUHAN BAKTERI PATOGEN PADA PROSES PRODUKSI TAPIOKA [Addition of Encapsulated Lactic Acid Bacteria to Suppress the Growth of Pathogenic Bacteria during Tapioca Production

Directory of Open Access Journals (Sweden)

Glisina Dwinoor Rembulan

2015-07-01

Full Text Available Lactic acid bacteria (LAB produce organic acids and active compounds which can inhibit the growth of pathogenic bacteria. Lactic acid bacteria potentially can be introduced to inhibit pathogenic bacteria in the tapioca production at the extraction stage, especially during the settling process since there is possibility of starch slurry to be contaminated by pathogenic bacteria from water. The objectives of this research were to design a solid starter of LAB through encapsulation by using modified starch includes sour cassava starch, lintnerized cassava starch and nanocrystalline starch, utilize the starter for suppressing the growth of pathogenic bacteria in the production process of tapioca and characterize the functional properties of tapioca. The encapsulation of lactic acid bacteria was conducted by freeze drying at a temperature of -50°C for 48 hours. The viability of LAB after freeze drying with sour cassava starch matrix was 92% of the liquid starter, with lintnerized cassava starch matrix was 93%, while that with nanocrystalline matrix was 96%. After application of the LAB culture during settling process for tapioca extraction and the tapioca was stored at room temperature for 6 months, it was shown that E. coli, Salmonella and Shigella were  detected in the native tapioca starch (without treatment while the starch added with lactic acid bacteria starter was not absent for the pathogenic bacteria. The addition of lactic acid bacteria in extraction process can suppress the growth of pathogenic bacteria in tapioca. The results showed that lintnerized cassava starch matrix is the best matrix because after 6 months it still contained lactic acid bacteria as compared to liquid starter and that encapsulated with other matrixes.

Characterization of radiation-resistant vegetative bacteria in beef

International Nuclear Information System (INIS)

Welch, A.B.; Maxcy, R.B.

1975-01-01

Ground beef contains numerous microorganisms of various types. The commonly recognized bacteria are associated with current problems of spoilage. Irradiation, however, contributes a new factor through selective destruction of the microflora. The residual microorganisms surviving a nonsterilizing dose are predominantly gram-negative coccobacilli. Various classifications have been given, e.g., Moraxella, Acinetobacter, Achromobacter, etc. For a more detailed study of these radiation-resistant bacteria occurring in ground beef, an enrichment procedure was used for isolation. By means of morphological and biochemical tests, most of the isolates were found to be Moraxella, based on current classifications. The range of growth temperatures was from 2 to 50 C. These bacteria were relatively heat sensitive, e.g., D 10 of 5.4 min at 70 0 C or less. The radiation resistance ranged from D 10 values of 273 to 2,039 krad. Thus, some were more resistant than any presently recognized spores. A reference culture of Moraxella osloensis was irradiated under conditions comparable to the enrichment procedure used with the ground beef. The only apparent changes were in morphology and penicillin sensitivity. However, after a few subcultures these bacteria reverted to the characteristics of the parent strain. Thus, it is apparent that these isolates are a part of the normal flora of ground beef and not aberrant forms arising from the irradiation procedure. The significance, if any, of these bacteria is not presently recognized. (auth)

Silver enhances antibiotic activity against gram-negative bacteria.

Science.gov (United States)

Morones-Ramirez, J Ruben; Winkler, Jonathan A; Spina, Catherine S; Collins, James J

2013-06-19

A declining pipeline of clinically useful antibiotics has made it imperative to develop more effective antimicrobial therapies, particularly against difficult-to-treat Gram-negative pathogens. Silver has been used as an antimicrobial since antiquity, yet its mechanism of action remains unclear. We show that silver disrupts multiple bacterial cellular processes, including disulfide bond formation, metabolism, and iron homeostasis. These changes lead to increased production of reactive oxygen species and increased membrane permeability of Gram-negative bacteria that can potentiate the activity of a broad range of antibiotics against Gram-negative bacteria in different metabolic states, as well as restore antibiotic susceptibility to a resistant bacterial strain. We show both in vitro and in a mouse model of urinary tract infection that the ability of silver to induce oxidative stress can be harnessed to potentiate antibiotic activity. Additionally, we demonstrate in vitro and in two different mouse models of peritonitis that silver sensitizes Gram-negative bacteria to the Gram-positive-specific antibiotic vancomycin, thereby expanding the antibacterial spectrum of this drug. Finally, we used silver and antibiotic combinations in vitro to eradicate bacterial persister cells, and show both in vitro and in a mouse biofilm infection model that silver can enhance antibacterial action against bacteria that produce biofilms. This work shows that silver can be used to enhance the action of existing antibiotics against Gram-negative bacteria, thus strengthening the antibiotic arsenal for fighting bacterial infections.

The interaction of bacteria and metal surfaces

International Nuclear Information System (INIS)

Mansfeld, Florian

2007-01-01

This review discusses different examples for the interaction of bacteria and metal surfaces based on work reported previously by various authors and work performed by the author with colleagues at other institutions and with his graduate students at CEEL. Traditionally it has been assumed that the interaction of bacteria with metal surfaces always causes increased corrosion rates ('microbiologically influenced corrosion' (MIC)). However, more recently it has been observed that many bacteria can reduce corrosion rates of different metals and alloys in many corrosive environments. For example, it has been found that certain strains of Shewanella can prevent pitting of Al 2024 in artificial seawater, tarnishing of brass and rusting of mild steel. It has been observed that corrosion started again when the biofilm was killed by adding antibiotics. The mechanism of corrosion protection seems to be different for different bacteria since it has been found that the corrosion potential E corr became more negative in the presence of Shewanella ana and algae, but more positive in the presence of Bacillus subtilis. These findings have been used in an initial study of the bacterial battery in which Shewanella oneidensis MR-1 was added to a cell containing Al 2024 and Cu in a growth medium. It was found that the power output of this cell continuously increased with time. In the microbial fuel cell (MFC) bacteria oxidize the fuel and transfer electrons directly to the anode. In initial studies EIS has been used to characterize the anode, cathode and membrane properties for different operating conditions of a MFC that contained Shewanella oneidensis MR-1. Cell voltage (V)-current density (i) curves were obtained using potentiodynamic sweeps. The current output of a MFC has been monitored for different experimental conditions

The interaction of bacteria and metal surfaces

Energy Technology Data Exchange (ETDEWEB)

Mansfeld, Florian [Corrosion and Environmental Effects Laboratory (CEEL), The Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA 90089-0241 (United States)

2007-10-10

This review discusses different examples for the interaction of bacteria and metal surfaces based on work reported previously by various authors and work performed by the author with colleagues at other institutions and with his graduate students at CEEL. Traditionally it has been assumed that the interaction of bacteria with metal surfaces always causes increased corrosion rates ('microbiologically influenced corrosion' (MIC)). However, more recently it has been observed that many bacteria can reduce corrosion rates of different metals and alloys in many corrosive environments. For example, it has been found that certain strains of Shewanella can prevent pitting of Al 2024 in artificial seawater, tarnishing of brass and rusting of mild steel. It has been observed that corrosion started again when the biofilm was killed by adding antibiotics. The mechanism of corrosion protection seems to be different for different bacteria since it has been found that the corrosion potential E{sub corr} became more negative in the presence of Shewanella ana and algae, but more positive in the presence of Bacillus subtilis. These findings have been used in an initial study of the bacterial battery in which Shewanella oneidensis MR-1 was added to a cell containing Al 2024 and Cu in a growth medium. It was found that the power output of this cell continuously increased with time. In the microbial fuel cell (MFC) bacteria oxidize the fuel and transfer electrons directly to the anode. In initial studies EIS has been used to characterize the anode, cathode and membrane properties for different operating conditions of a MFC that contained Shewanella oneidensis MR-1. Cell voltage (V) - current density (i) curves were obtained using potentiodynamic sweeps. The current output of a MFC has been monitored for different experimental conditions. (author)

Characterization of lactic acid bacteria from local cow´s milk kefir

Science.gov (United States)

Ismail, YS; Yulvizar, C.; Mazhitov, B.

2018-03-01

One of products from milk fermentation is kefir. It is made by adding kefir grains which are composed of lactic acid bacteria and yeast into milk. The lactic acid bacteria are a group of bacteria that produce antimicrobial substances and able to inhibit the growth of pathogenic bacteria. In this research, the lactic acid bacteria were isolated from Aceh local cow`s milk kefir to determine the genus of the isolates. The methods used in the characterization of lactic acid bacteria are colony morphology, cell morphology, and biochemical tests which includes a catalase test; 5%, 6.5%, and 10% salt endurance tests; 37°C and 14°C temperature endurance tests, SIM test, TSIA test, MR-VP test, and O/F test. Of the four isolates found from the cow’s milk kefir, two isolates were confirmed as lactic acid bacteria (isolates SK-1 and SK-4). Both isolates are Gram positive bacteria, and have negative catalase activity. From the observations of colony morphology, cell morphology, and biochemical tests, it was found that the genus of SK-1 is Lactobacillus and the genus of SK-4 is Enterococcus.

The Composition of Colonic Commensal Bacteria According to Anatomical Localization in Colorectal Cancer

Directory of Open Access Journals (Sweden)

Liuyang Zhao

2017-02-01

Full Text Available Colorectal cancer (CRC is a multistage disease resulting from complex factors, including genetic mutations, epigenetic changes, chronic inflammation, diet, and lifestyle. Recent accumulating evidence suggests that the gut microbiota is a new and important player in the development of CRC. Imbalance of the gut microbiota, especially dysregulated gut bacteria, contributes to colon cancer through mechanisms of inflammation, host defense modulations, oxidative stress, and alterations in bacterial-derived metabolism. Gut commensal bacteria are anatomically defined as four populations: luminal commensal bacteria, mucus-resident bacteria, epithelium-resident bacteria, and lymphoid tissue-resident commensal bacteria. The bacterial flora that are harbored in the gastrointestinal (GI tract vary both longitudinally and cross-sectionally by different anatomical localization. It is notable that the translocation of colonic commensal bacteria is closely related to CRC progression. CRC-associated bacteria can serve as a non-invasive and accurate biomarker for CRC diagnosis. In this review, we summarize recent findings on the oncogenic roles of gut bacteria with different anatomical localization in CRC progression.

Vibrio bacteria in raw oysters: managing risks to human health.

Science.gov (United States)

Froelich, Brett A; Noble, Rachel T

2016-03-05

The human-pathogenic marine bacteria Vibrio vulnificus and V. parahaemolyticus are strongly correlated with water temperature, with concentrations increasing as waters warm seasonally. Both of these bacteria can be concentrated in filter-feeding shellfish, especially oysters. Because oysters are often consumed raw, this exposes people to large doses of potentially harmful bacteria. Various models are used to predict the abundance of these bacteria in oysters, which guide shellfish harvest policy meant to reduce human health risk. Vibrio abundance and behaviour varies from site to site, suggesting that location-specific studies are needed to establish targeted risk reduction strategies. Moreover, virulence potential, rather than simple abundance, should be also be included in future modeling efforts. © 2016 The Author(s).

Interactions between the microbiota and pathogenic bacteria in the gut.

Science.gov (United States)

Bäumler, Andreas J; Sperandio, Vanessa

2016-07-07

The microbiome has an important role in human health. Changes in the microbiota can confer resistance to or promote infection by pathogenic bacteria. Antibiotics have a profound impact on the microbiota that alters the nutritional landscape of the gut and can lead to the expansion of pathogenic populations. Pathogenic bacteria exploit microbiota-derived sources of carbon and nitrogen as nutrients and regulatory signals to promote their own growth and virulence. By eliciting inflammation, these bacteria alter the intestinal environment and use unique systems for respiration and metal acquisition to drive their expansion. Unravelling the interactions between the microbiota, the host and pathogenic bacteria will produce strategies for manipulating the microbiota against infectious diseases.

Interactions between the microbiota and pathogenic bacteria in the gut

Science.gov (United States)

Bäumler, Andreas J.; Sperandio, Vanessa

2016-01-01

The microbiome has an important role in human health. Changes in the microbiota can confer resistance to or promote infection by pathogenic bacteria. Antibiotics have a profound impact on the microbiota that alters the nutritional landscape of the gut and can lead to the expansion of pathogenic populations. Pathogenic bacteria exploit microbiota-derived sources of carbon and nitrogen as nutrients and regulatory signals to promote their own growth and virulence. By eliciting inflammation, these bacteria alter the intestinal environment and use unique systems for respiration and metal acquisition to drive their expansion. Unravelling the interactions between the microbiota, the host and pathogenic bacteria will produce strategies for manipulating the microbiota against infectious diseases. PMID:27383983

Isolation and identification of marine fish tumour (odontoma associated bacteria

Directory of Open Access Journals (Sweden)

Ramalingam Vijayakumar

2015-09-01

Full Text Available Objective: To identify fish tumour associated bacteria. Methods: The marine fish Sphyraena jello with odontoma was collected from in Tamil Nadu (Southeast India, and tumour associated bacteria were isolated. Then the isolated bacteria were identified based on molecular characters. Results: A total of 4 different bacterial species were isolated from tumour tissue. The bacterial species were Bacillus sp., Pontibacter sp., Burkholderia sp. and Macrococcus sp., and the sequences were submitted in DNA Data Bank of Japan with accession numbers of AB859240, AB859241, AB859242 and AB859243 respectively. Conclusions: Four different bacterial species were isolated from Sphyraena jello, but the role of bacteria within tumour needs to be further investigated.

Electro-responsive supramolecular graphene oxide hydrogels for active bacteria adsorption and removal

Science.gov (United States)

Xue, Bin; Cao, Yi; Wang, Wei

Bacteria are major contaminations in drinking water and healthcare products. Bacteria contamination may cause severe health problems, including food poisoning and diseases. Currently water sterilization and purification methods to remove contaminated bacteria are mainly based on the size-exclusion mechanism. In order to completely remove all bacteria in water, the pore sizes of the membranes or cartilages should be comparable to the size of bacteria, which inevitable leads to high cross-membrane water pressure and slow purification speed. Moreover, the membranes can easily get clogged. Therefore it is highly demanded to develop efficient methods and novel materials for water purification. Recently, Cui and coworker have introduced a bacteria inactivation method with high efficiency and fast purification speed based on a kind of complex materials made of silver nanofibers, carbon nanotubes and cotton, operating in an electric field. With the help of electric field, the bacteria can be efficiently kill when passing through the membrance even the pore sizes are larger than bacteria. Inspired by their work, here we report a proof-of-principle demonstration of bacteria removal using electro-reponsive hydrogels. This work is funded by Six talent peaks project in Jiangsu Province, the National Natural Science Foundation of China (Nos. 11304156, 11334004, 31170813, 81421091 and 91127026), the 973 Program of China (No. 2012CB921801 and 2013CB834100), the Priority Ac.

Host and symbiont intraspecific variability: The case of Paramecium calkinsi and "Candidatus Trichorickettsia mobilis".

Science.gov (United States)

Sabaneyeva, E; Castelli, M; Szokoli, F; Benken, K; Lebedeva, N; Salvetti, A; Schweikert, M; Fokin, S; Petroni, G

2018-02-01

Newly isolated strains of the ciliate Paramecium calkinsi and their cytoplasmic bacterial endosymbionts were characterized by a multidisciplinary approach, including live observation, ultrastructural investigation, and molecular analysis. Despite morphological resemblance, the characterized P. calkinsi strains showed a significant molecular divergence compared to conspecifics, possibly hinting for a cryptic speciation. The endosymbionts were clearly found to be affiliated to the species "Candidatus Trichorickettsia mobilis" (Rickettsiales, Rickettsiaceae), currently encompassing only bacteria retrieved in an obligate intracellular association with other ciliates. However, a relatively high degree of intraspecific divergence was observed as well, thus it was possible to split "Candidatus Trichorickettsia" into three subspecies, one of which represented so far only by the newly characterized endosymbionts of P. calkinsi. Other features distinguished the members of each different subspecies. In particular, the endosymbionts of P. calkinsi resided in the cytoplasm and possessed numerous peritrichous flagella, although no motility was evidenced, whereas their conspecifics in other hosts were either cytoplasmic and devoid of flagella, or macronuclear, displaying flagellar-driven motility. Moreover, contrarily to previously analyzed "Candidatus Trichorickettsia" hosts, infected P. calkinsi cells frequently became amicronucleate and demonstrated abnormal cell division, eventually leading to decline of the laboratory culture. Copyright © 2017 Elsevier GmbH. All rights reserved.

Investigation of biosurfactant-producing indigenous microorganisms that enhance residue oil recovery in an oil reservoir after polymer flooding.

Science.gov (United States)

She, Yue-Hui; Zhang, Fan; Xia, Jing-Jing; Kong, Shu-Qiong; Wang, Zheng-Liang; Shu, Fu-Chang; Hu, Ji-Ming

2011-01-01

Three biosurfactant-producing indigenous microorganisms (XDS1, XDS2, XDS3) were isolated from a petroleum reservoir in the Daqing Oilfield (China) after polymer flooding. Their metabolic, biochemical, and oil-degradation characteristics, as well as their oil displacement in the core were studied. These indigenous microorganisms were identified as short rod bacillus bacteria with white color, round shape, a protruding structure, and a rough surface. Strains have peritrichous flagella, are able to produce endospores, are sporangia, and are clearly swollen and terminal. Bacterial cultures show that the oil-spreading values of the fermentation fluid containing all three strains are more than 4.5 cm (diameter) with an approximate 25 mN/m surface tension. The hydrocarbon degradation rates of each of the three strains exceeded 50%, with the highest achieving 84%. Several oil recovery agents were produced following degradation. At the same time, the heavy components of crude oil were degraded into light components, and their flow characteristics were also improved. The surface tension and viscosity of the crude oil decreased after being treated by the three strains of microorganisms. The core-flooding tests showed that the incremental oil recoveries were 4.89-6.96%. Thus, XDS123 treatment may represent a viable method for microbial-enhanced oil recovery.

Unusual rise in mercury-resistant bacteria in coastal environs

Digital Repository Service at National Institute of Oceanography (India)

Ramaiah, N.; De, J.

A sharp rise in mercury-resistant bacteria (MRB) capable of tolerating very high concentration of Hg was observed over the last 3-4 years in the coastal environs of India. While none or negligible colony-forming units (CFU) of bacteria were counted...

Population dynamics of bacteria introduced into bentonite amended soil

NARCIS (Netherlands)

Heijnen, C.

1992-01-01

Bacteria have frequently been introduced into the soil environment, e.g. for increasing crop production or for biological control purposes. Many applications require high numbers of surviving organisms in order to be effective. However, survival of bacteria after introduction into soil is

Gram-positive bacteria persisting in the food production environment

DEFF Research Database (Denmark)

Knøchel, Susanne; Harmsen, Morten; Knudsen, Bettina

2008-01-01

Many gram-positive bacteria are able to form aggregates or biofilms and resist external stress factors and some gram-positive pathogenic bacteria such as Listeria monocytogenes and Bacillus cereus may persist in the food production environment for extended periods. Most research has focussed...

Degradation of riverine dissolved organic matter by seawater bacteria

NARCIS (Netherlands)

Rochelle-Newall, E.J.; Pizay, M-D.; Middelburg, J.J.; Boschker, H.T.S.; Gattuso, J.P.

2004-01-01

The functional response of a seawater bacterial community transplanted into freshwater dissolved organic matter (DOM) was investigated together with the response of natural populations of bacteria to size-fractioned natural source water. Seawater bacteria were incubated over a period of 8 d in

DIRECT FLOW-CYTOMETRY OF ANAEROBIC-BACTERIA IN HUMAN FECES

NARCIS (Netherlands)

VANDERWAAIJ, LA; MESANDER, G; LIMBURG, PC; VANDERWAAIJ, D

1994-01-01

We describe a flow cytometry method for analysis of noncultured anaerobic bacteria present in human fecal suspensions. Nonbacterial fecal compounds, bacterial fragments, and large aggregates could be discriminated from bacteria by staining with propidium iodide (PI) and setting a discriminator on PI

The effects of bacteria on the corrosion behavior of carbon steel in compacted bentonite

International Nuclear Information System (INIS)

Nishimura, T.; Wada, R.; Nishimoto, H.; Fujiwara, K.; Taniguchi, N.; Honda, A.

1999-10-01

As a part of evaluation of corrosion life of carbon steel overpack, the experimental studies have been performed on the effects of bacteria on the corrosion behavior of carbon steel in compacted bentonite using iron bacteria (IB) as a representative oxidizing bacteria and sulphur reducing bacteria (SRB) as a representative reducing bacteria. The results of the experimental studies showed that; The activity of SRB was low in compacted bentonite in spite of applying suitable condition for the action of bacteria such as temperature and nutritious solution. Although the corrosion behavior of carbon steel was affected by the existence of bacteria in simple solution, the corrosion rates of carbon steel in compacted bentonite were several μ m/year -10 μ m/year irrespective of coexistence of bacteria and that the corrosion behavior was not affected by the existence of bacteria. According to these results, it was concluded that the bacteria would not affect the corrosion behavior of carbon steel overpack under repository condition. (author)

SERS substrates fabricated using ceramic filters for the detection of bacteria

Science.gov (United States)

Mosier-Boss, P. A.; Sorensen, K. C.; George, R. D.; Obraztsova, A.

2016-01-01

SERS substrates were fabricated by filtering either Ag or Au colloidal particles onto rigid, ceramic filters - onto which suspensions of bacteria were then filtered. SERS spectra of the bacteria were obtained using a Raman spectrometer that has an 'orbital raster scan' capability. It was shown that bacteria samples prepared in this manner were uniformly distributed onto the surface of the SERS substrate. The effect of common buffer systems on the SERS spectra was investigated and the utility of using the SERS technique for speciation of bacteria was explored.

Multidrug resistance in enteric and other gram-negative bacteria.

Science.gov (United States)

George, A M

1996-05-15

In Gram-negative bacteria, multidrug resistance is a term that is used to describe mechanisms of resistance by chromosomal genes that are activated by induction or mutation caused by the stress of exposure to antibiotics in natural and clinical environments. Unlike plasmid-borne resistance genes, there is no alteration or degradation of drugs or need for genetic transfer. Exposure to a single drug leads to cross-resistance to many other structurally and functionally unrelated drugs. The only mechanism identified for multidrug resistance in bacteria is drug efflux by membrane transporters, even though many of these transporters remain to be identified. The enteric bacteria exhibit mostly complex multidrug resistance systems which are often regulated by operons or regulons. The purpose of this review is to survey molecular mechanisms of multidrug resistance in enteric and other Gram-negative bacteria, and to speculate on the origins and natural physiological functions of the genes involved.

Metagenomic analysis reveals symbiotic relationship among bacteria in Microcystis-dominated community

Directory of Open Access Journals (Sweden)

Meili eXie

2016-02-01

Full Text Available Microcystis bloom, a cyanobacterial mass occurrence often found in eutrophicated water bodies, is one of the most serious threats to freshwater ecosystems worldwide. In nature, Microcystis forms aggregates or colonies that contain heterotrophic bacteria. The Microcystis-bacteria colonies were persistent even when they were maintained in lab culture for a long period. The relationship between Microcystis and the associated bacteria was investigated by a metagenomic approach in this study. We developed a visualization-guided method of binning for genome assembly after total colony DNA sequencing. We found that the method was effective in grouping sequences and it did not require reference genome sequence. Individual genomes of the colony bacteria were obtained and they provided valuable insights into microbial community structures. Analysis of metabolic pathways based on these genomes revealed that while all heterotrophic bacteria were dependent upon Microcystis for carbon and energy, Vitamin B12 biosynthesis, which is required for growth by Microcystis, was accomplished in a cooperative fashion among the bacteria. Our analysis also suggests that individual bacteria in the colony community contributed a complete pathway for degradation of benzoate, which is inhibitory to the cyanobacterial growth, and its ecological implication for Microcystis bloom is discussed.

Armpits, Belly Buttons and Chronic Wounds: The ABCs of Our Body Bacteria

Science.gov (United States)

... and Chronic Wounds: The ABCs of Our Body Bacteria By Alisa Machalek and Allison MacLachlan Posted April ... treating skin and other conditions. Chronic Wounds and Bacteria Bacteria from human skin grown on agar in ...

Pronounced daily succession of phytoplankton, archaea and bacteria following a spring bloom.

Science.gov (United States)

Needham, David M; Fuhrman, Jed A

2016-02-29

Marine phytoplankton perform approximately half of global carbon fixation, with their blooms contributing disproportionately to carbon sequestration(1), and most phytoplankton production is ultimately consumed by heterotrophic prokaryotes(2). Therefore, phytoplankton and heterotrophic community dynamics are important in modelling carbon cycling and the impacts of global change(3). In a typical bloom, diatoms dominate initially, transitioning over several weeks to smaller and motile phytoplankton(4). Here, we show unexpected, rapid community variation from daily rRNA analysis of phytoplankton and prokaryotic community members following a bloom off southern California. Analysis of phytoplankton chloroplast 16S rRNA demonstrated ten different dominant phytoplankton over 18 days alone, including four taxa with animal toxin-producing strains. The dominant diatoms, flagellates and picophytoplankton varied dramatically in carbon export potential. Dominant prokaryotes also varied rapidly. Euryarchaea briefly became the most abundant organism, peaking over a few days to account for about 40% of prokaryotes. Phytoplankton and prokaryotic communities correlated better with each other than with environmental parameters. Extending beyond the traditional view of blooms being controlled primarily by physics and inorganic nutrients, these dynamics imply highly heterogeneous, continually changing conditions over time and/or space and suggest that interactions among microorganisms are critical in controlling plankton diversity, dynamics and fates.

Aerobic salivary bacteria in wild and captive Komodo dragons.

Science.gov (United States)

Montgomery, Joel M; Gillespie, Don; Sastrawan, Putra; Fredeking, Terry M; Stewart, George L

2002-07-01

During the months of November 1996, August 1997, and March 1998, saliva and plasma samples were collected for isolation of aerobic bacteria from 26 wild and 13 captive Komodo dragons (Varanus komodoensis). Twenty-eight Gram-negative and 29 Gram-positive species of bacteria were isolated from the saliva of the 39 Komodo dragons. A greater number of wild than captive dragons were positive for both Gram-negative and Gram-positive bacteria. The average number of bacterial species within the saliva of wild dragons was 46% greater than for captive dragons. While Escherichia coli was the most common bacterium isolated from the saliva of wild dragons, this species was not present in captive dragons. The most common bacteria isolated from the saliva of captive dragons were Staphylococcus capitis and Staphylococcus capitis and Staphylococcus caseolyticus, neither of which were found in wild dragons. High mortality was seen among mice injected with saliva from wild dragons and the only bacterium isolated from the blood of dying mice was Pasteurella multocida. A competitive inhibition enzyme-linked immunosorbent assay revealed the presence of anti-Pasteurella antibody in the plasma of Komodo dragons. Four species of bacteria isolated from dragon saliva showed resistance to one or more of 16 antimicrobics tested. The wide variety of bacteria demonstrated in the saliva of the Komodo dragon in this study, at least one species of which was highly lethal in mice and 54 species of which are known pathogens, support the observation that wounds inflicted by this animal are often associated with sepsis and subsequent bacteremia in prey animals.

Social behavior of bacteria: from physics to complex organization

Science.gov (United States)

Ben-Jacob, E.

2008-10-01

I describe how bacteria develop complex colonial patterns by utilizing intricate communication capabilities, such as quorum sensing, chemotactic signaling and exchange of genetic information (plasmids) Bacteria do not store genetically all the information required for generating the patterns for all possible environments. Instead, additional information is cooperatively generated as required for the colonial organization to proceed. Each bacterium is, by itself, a biotic autonomous system with its own internal cellular informatics capabilities (storage, processing and assessments of information). These afford the cell certain plasticity to select its response to biochemical messages it receives, including self-alteration and broadcasting messages to initiate alterations in other bacteria. Hence, new features can collectively emerge during self-organization from the intra-cellular level to the whole colony. Collectively bacteria store information, perform decision make decisions (e.g. to sporulate) and even learn from past experience (e.g. exposure to antibiotics)-features we begin to associate with bacterial social behavior and even rudimentary intelligence. I also take Schrdinger’s’ “feeding on negative entropy” criteria further and propose that, in addition organisms have to extract latent information embedded in the environment. By latent information we refer to the non-arbitrary spatio-temporal patterns of regularities and variations that characterize the environmental dynamics. In other words, bacteria must be able to sense the environment and perform internal information processing for thriving on latent information embedded in the complexity of their environment. I then propose that by acting together, bacteria can perform this most elementary cognitive function more efficiently as can be illustrated by their cooperative behavior.

Impacts of radiation exposure on the experimental microbial ecosystem: a particle-based model simulation approach

International Nuclear Information System (INIS)

Doi, M.; Tanaka, N.; Fuma, S.; Kawabata, Z.

2004-01-01

Well-designed experimental model ecosystem could be a simple reference of the actual environment and complex ecological systems. For ecological toxicity test of radiation and other environmental toxicants, we investigated and aquatic microbial ecosystem (closed microcosm) in the test tube with initial substrates,autotroph flagellate algae (Euglena, G.), heterotroph ciliate protozoa (Tetrahymena T.) and saprotroph bacteria (E, coli). These species organizes by itself to construct the ecological system, that keeps the sustainable population dynamics for more than 2 years after inoculation only by adding light diurnally and controlling temperature at 25 degree Celsius. Objective of the study is to develop the particle-based computer simulation by reviewing interactions among microbes and environment, and analyze the ecological toxicities of radiation on the microcosm by replicating experimental results in the computer simulation. (Author) 14 refs

Action of sodium deoxycholate on Escherichia coli

International Nuclear Information System (INIS)

D'Mello, A.; Yotis, W.W.

1987-01-01

Sodium deoxycholate is used in a number of bacteriological media for the isolation and classification of gram-negative bacteria from food and the environment. Initial experiments to study the effect of deoxycholate on the growth parameters of Escherichia coli showed an increase in the lag time constant and generation time and a decrease in the growth rate constant total cell yield of this microorganisms. Cell fractionation studies indicated that sodium deoxycholate at levels used in bacteriological media interferes with the incorporation of [U- 14 C]glucose into the cold-trichloroacetic acid-soluble, ethanol-soluble, and trypsin-soluble cellular fractions of E. coli. Finally, sodium deoxycholate interfered with the flagellation and motility of Proteus mirabilis and E. coli. It would appear then that further improvement of the deoxycholate medium may be in order

Action of sodium deoxycholate on Escherichia coli

Energy Technology Data Exchange (ETDEWEB)

D' Mello, A.; Yotis, W.W.

1987-08-01

Sodium deoxycholate is used in a number of bacteriological media for the isolation and classification of gram-negative bacteria from food and the environment. Initial experiments to study the effect of deoxycholate on the growth parameters of Escherichia coli showed an increase in the lag time constant and generation time and a decrease in the growth rate constant total cell yield of this microorganisms. Cell fractionation studies indicated that sodium deoxycholate at levels used in bacteriological media interferes with the incorporation of (U-/sup 14/C)glucose into the cold-trichloroacetic acid-soluble, ethanol-soluble, and trypsin-soluble cellular fractions of E. coli. Finally, sodium deoxycholate interfered with the flagellation and motility of Proteus mirabilis and E. coli. It would appear then that further improvement of the deoxycholate medium may be in order.

Taxonomy and Physiology of un-wanted bacterial flora in activated sludge process. Study in a pilot plant; Taxonomia y fisiologia de la flora bacteriana indeseable en el proceso de fangos activados. Estudio de una plant piloto

Energy Technology Data Exchange (ETDEWEB)