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Anode-respiring bacteria (ARB) are able to transfer electrons contained in organic substrates to a solid electrode. The selection of ARB should depend on the anode potential, which determines the amount of energy available for bacterial growth and maintenance. In our study, we investigated how anode potential affected the microbial diversity of the biofilm community. We used a microbial electrolysis cell (MEC) containing four graphite electrodes, each at a different anode potential (Eanode = -0.15, -0.09, +0.02, and +0.37 V vs SHE). We used wastewater-activated sludge as inoculum, acetate as substrate, and continuous-flow operation. The two electrodes at the lowest potentials showed a faster biofilm growth and produced the highest current densities, reaching up to 10.3 A/m² at the saturation of an amperometric curve; the electrode at the highest potential produced a maximum of 0.6 A/m². At low anode potentials, clone libraries showed a strong selection (92-99% of total clones) of an ARB that is 97% similar to G. sulfurreducens. At the highest anode potential, the ARB community was diverse. Cyclic voltammograms performed on each electrode suggest that the ARB grown at the lowest potentials carried out extracellular electron transport exclusively by conducting electrons through the extracellular biofilm matrix. This is supported by scanning electron micrographs showing putative bacterial nanowires and copious EPS at the lowest potentials. Non-ARB and ARB using electron shuttles in the diverse community for the highest anode potential may have insulated the ARB using a solid conductive matrix from the anode. Continuous-flow operation and the selective pressure due to low anode potentials selected for G. sulfurreducens, which are known to consume acetate efficiently and use a solid conductive matrix for electron transport. [ABSTRACT FROM AUTHOR]

Viability of multiple antibiotic resistant bacteria (MARB) in tertiary treated sewage effluent (TTSE) used for irrigation, was investigated at the Sultan Qaboos University sewage treatment plant (STP). This water recycle system is used here as a model for the systems commonly used throughout Oman and the Gulf region. Samples of TTSE were collected weekly from four sites, 1.5km from each other. Chlorine levels declined gradually at the three sites with increasing distance from the STP. Viable bacteria, coliforms and nitrate concentrations increased significantly while biological oxygen demand (BOD) declined after STP chlorination. Mean values of turbidity changed slightly. Trace elements values were insignificant. A total of 336 bacteria from 8 genera revealed that the dominant isolates were Enterobacter spp., Pseudomonas spp., and Aeromonas spp. Among the isolates 59.8% were multiply resistant to several antibiotics. Resistance was higher to ampicillin followed by sulphamethoxazole, carbenicillin, streptomycine and minocycline. Frequency of resistance to the 14 antibiotics varied among the isolates. The present system related to the viability of MARB in TTSE used for irrigation may have serious implications for public health and wildlife. Results of this investigation will be of value in modifying current STPs systems and thus avoiding serious health issues. [ABSTRACT FROM AUTHOR]

Automatic fault detection is becoming increasingly important in wastewater treatment plant operation, given the stringent treatment standards and the need to protect the investment costs from the potential damage of an unchecked fault propagating through the plant. This paper describes the development of a real-time Fault Detection and Isolation (FDI) system based on an adaptive Principal Component Analysis (PCA) algorithm, used to compare the current plant operation with a correct performance model based on a reference data set and the output of three ion-specific sensors (Hach-Lange gmbh, Düsseldorf, Germany): two Nitratax® NOx UV sensors, in the denitrification tank and downstream of the oxidation tanks, where an Amtax® ammonium-N sensor was also installed. The algorithm was initially developed in the Matlab environment and then ported into the LabView 8.20 (National Instruments, Austin, TX, USA) platform for real-time operation using a compact Field Point ®, a Programmable Automation Controller by National Instruments. The FDI was tested with a large set of operational data with 1 min sampling time from August 2007 through May 2008 from a full-scale plant. After describing the real-time version of the PCA algorithm, this was tested with nine months of operational data which were sequentially processes by the algorithm in order to simulate an on-line operation. The FDI performance was assessed by organizing the sequential data in two differing moving windows: a short-horizon window to test the response to single malfunctions and a longer time-horizon to simulate multiple unrepaired failures. In both cases the algorithm performance was very satisfactory, with a 100% failure detection in the short window case, which decreased to 84% in the long window setting. The short-window performance was very effective in isolating sensor failures and short duration disturbances such as spikes, whereas the long term horizon provided accurate detection of long-term drifts and proved robust enough to allow for some delay in failure recovery. The system robustness is based on the use of multiple statistics which proved instrumental in discriminating among the various causes of malfunctioning. [ABSTRACT FROM AUTHOR]

Introduction of diazotrophic rhizobacteria to oil palm tissues during the in vitro micropropagation process establishes an early associative interaction between the plant cells and bacteria. In the association, the diazotrophs provide the host plants with phytohormones and fixed nitrogen. This study was conducted to observe growth of bacterised tissue cultured oil palm plants under ex vitro conditions after 280 days of growth. Root dry weight, shoot dry weight, root volume, bacterial colonisation, leaf protein and chlorophyll content of the host plants were observed. The results revealed that the inocula successfully colonised roots of the host plants. Plants inoculated with Acetobacter diazotrophicus (R12) had more root dry weight and volume than plants inoculated with Azospirillum brasilense (Sp7). Leaf protein and chlorophyll content were higher in the bacterised plants compared to Control 2 plants (inoculated with killed Sp7). These results suggest that the diazotrophs successfully improved the growth of the host plant (oil palm) and minimised the amount of N fertiliser necessary for growth. [ABSTRACT FROM AUTHOR]

Background: The loss of photosynthesis has occurred often in eukaryotic evolution, even more than its acquisition, which occurred at least nine times independently and which generated the evolution of the supergroups Archaeplastida, Rhizaria, Chromalveolata and Excavata. This secondary loss of autotrophic capability is essential to explain the evolution of eukaryotes and the high diversity of protists, which has been severely underestimated until recently. However, the ecological and evolutionary scenarios behind this evolutionary ''step back'' are still largely unknown. Methodology/Principal Findings: Using a dynamic model of heterotrophic and mixotrophic flagellates and two types of prey, large bacteria and ultramicrobacteria, we examine the influence of DOC concentration, mixotroph's photosynthetic growth rate, and external limitations of photosynthesis on the coexistence of both types of flagellates. Our key premises are: large bacteria grow faster than small ones at high DOC concentrations, and vice versa; and heterotrophic flagellates are more efficient than the mixotrophs grazing small bacteria (both empirically supported). We show that differential efficiency in bacteria grazing, which strongly depends on cell size, is a key factor to explain the loss of photosynthesis in mixotrophs (which combine photosynthesis and bacterivory) leading to purely heterotrophic lineages. Further, we show in what conditions an heterotroph mutant can coexist, or even out-compete, its mixotrophic ancestor, suggesting that bacterivory and cell size reduction may have been major triggers for the diversification of eukaryotes. Conclusions/Significance: Our results suggest that, provided the mixotroph's photosynthetic advantage is not too large, the (small) heterotroph will also dominate in nutrient-poor environments and will readily invade a community of mixotrophs and bacteria, due to its higher efficiency exploiting the ultramicrobacteria. As carbon-limited conditions were presumably widespread throughout Earth history, such a scenario may explain the numerous transitions from phototrophy to mixotrophy and further to heterotrophy within virtually all major algal lineages. We challenge prevailing concepts that affiliated the evolution of phagotrophy with eutrophic or strongly light-limited environments only. [ABSTRACT FROM AUTHOR]

A number of hypotheses have been suggested to explain why invasive exotic plants dramatically increase their abundance upon transport to a new range. The novel weapons hypothesis argues that phytotoxins secreted by roots of an exotic plant are more effective against naïve resident competitors in the range being invaded. The common reed Phragmites australis has a diverse population structure including invasive populations that are noxious weeds in North America. P. australis exudes the common phenolic gallic acid, which restricts the growth of native plants. However, the pathway for free gallic acid production in soils colonized by P. australis requires further elucidation. Here, we show that exotic, invasive P. australis contain elevated levels of polymeric gallotannin relative to native, noninvasive P. australis. We hypothesized that polymeric gallotannin can be attacked by tannase, an enzymatic activity produced by native plant and microbial community members, to release gallic acid in the rhizosphere and exacerbate the noxiousness of P. australis. Native plants and microbes were f und to produce high levels of tannase while invasive P. austrulis produced very little tannase. These results suggest that both invasive and native species participate in signaling events that initiate the execution of allelopathy potentially linking native plant and microbial biochemistry to the invasive traits of an exotic species. [ABSTRACT FROM AUTHOR]

Bacteria are constantly being transported through the atmosphere, which may have implications for human health, agriculture, cloud formation, and the dispersal of bacterial species. We simulate the global transport of bacteria, represented as 1μm and 3μm diameter spherical solid particle tracers in a general circulation model. We investigate factors influencing residence time and distribution of the particles, including emission region, cloud condensation nucleus activity and removal by ice-phase precipitation. The global distribution depends strongly on the assumptions made about uptake into cloud droplets and ice. The transport is also affected, to a lesser extent, by the emission region, particulate diameter, and season. We find that the seasonal variation in atmospheric residence time is insufficient to explain by itself the observed seasonal variation in concentrations of particulate airborne culturable bacteria, indicating that this variability is mainly driven by seasonal variations in culturability and/or emission strength. We examine the potential for exchange of bacteria between ecosystems and obtain rough estimates of the flux from each ecosystem by using a maximum likelihood estimation technique, together with a new compilation of available observations described in a companion paper. Globally, we estimate the total emissions of bacteria-containing particles to the atmosphere to be 7.6×1023-3.5×1024 a-1, originating mainly from grasslands, shrubs and crops. We estimate the mass of emitted bacteria- to be 40-1800 Gg a-1, depending on the mass fraction of bacterial cells in the particles. In order to improve understanding of this topic, more measurements of the bacterial content of the air and of the rate of surface-atmosphere exchange of bacteria will be necessary. Future observations in wetlands, hot deserts, tundra, remote glacial and coastal regions and over oceans will be of particular interest. [ABSTRACT FROM AUTHOR]

Bacteria are ubiquitous in the atmosphere, with concentrations of bacterial cells typically exceeding 1×104 m-3 over land. Numerous studies have suggested that the presence of bacteria in the atmosphere may impact cloud development, atmospheric chemistry, and microbial biogeography. A sound knowledge of bacterial concentrations and distributions in the atmosphere is needed to evaluate these claims. This review focusses on published measurements of total and culturable bacteria concentrations in the atmospheric aerosol. We discuss emission mechanisms and the impacts of meteorological conditions and measurement techniques on measured bacteria concentrations. Based on the literature reviewed, we suggest representative values and ranges for the mean concentration in the near-surface air of nine natural ecosystems and three human-influenced land types. We discuss the gaps in current knowledge of bacterial concentrations in air, including the lack of reliable, long-term measurements of the total microbial concentrations in many regions and the scarcity of emission flux measurements. [ABSTRACT FROM AUTHOR]

In this study, arsenic resistant bacteria were isolated from sediments of an arsenic contaminated river. Arsenic tolerance of bacteria isolated was carried out by serial dilution on agar plate. Redox abilities were investigated using KMnO4. arsC and aox genes were detected by PCR and RT-PCR, respectively. Bacterial populations were identified by RapID system. Forty nine bacterial strains were isolated, of these, 55 % corresponded to the reducing bacteria, 4% to oxidizing bacteria, 8% presented both activities and in 33% of the bacteria none activity was detected. arsC gene was detected in 11 strains and aox genes were not detected. The activity of arsenic transforming microorganisms in river sediment has significant implications for the behavior of the metalloid. [ABSTRACT FROM AUTHOR]

Methane is the most abundant hydrocarbon in the atmosphere, and it is an important greenhouse gas, which has so far contributed an estimated 20% of postindustrial global warming. A great deal of biogeochemical research has focused on the causes and effects of the variation in global fluxes of methane throughout earth's history, but the underlying microbial processes and their key agents remain poorly understood. This is a disturbing knowledge gap because 85% of the annual global methane production and about 60% of its consumption are based on microbial processes. Only three key functional groups of microorganisms of limited diversity regulate the fluxes of methane on earth, namely the aerobic methanotrophic bacteria, the methanogenic archaea, and their close relatives, the anaerobic methanotrophic archaea (ANME). The ANME represent special lines of descent within the Euryarchaeota and appear to gain energy exclusively from the anaerobic oxidation of methane (AOM), with sulfate as the final electron acceptor according to the net reaction: CH4 + SO2-4 → HCO-3 + HS- + H2O. This review summarizes what is known and unknown about AOM on earth and its key catalysts, the ANME clades and their bacterial partners. [ABSTRACT FROM AUTHOR]

Oxidative stress enzymes, superoxide dismutase (SOD), catalase (CAT), and ATPase, from two Gram-positive bacteria and one Gram-negative bacterium, respectively, were tested for response to the oxidative stress caused by bensulfuron-methyl (BSM). Native PAGE was used to detect the SOD isoenzyme profiles of these bacteria. All three bacteria possessed a basal level of SOD, CAT, and ATPase activity prior to being exposed to BSM. Enzyme activities changed in a BSM-concentration-dependent manner after exposure to BSM for 24h. Activity of all the enzymes was increased and reached the first activity peak after being exposed to BSM at 1 or 1.5h, respectively, then a decline occurred, and after that another simulation appeared at 9h or 14h. Only one and three detectable SOD isoenzyme bands were observed in Gram-positive strains and the Gram-negative strain, respectively. BSM could bring short-term ecotoxicity to three bacteria, but the effect of BSM was not lethal. [Copyright &y& Elsevier]

Arctic soils contain large amounts of organic matter due to very slow rates of detritus decomposition. The first step in decomposition results from the activity of extracellular enzymes produced by soil microbes. We hypothesized that potential enzyme activities are low relative to the large stocks of organic matter in Arctic tundra soils, and that enzyme activity is low at in situ temperatures. We measured the potential activity of six hydrolytic enzymes at 4 and 20 °C on four sampling dates in tussock, intertussock, shrub organic, and shrub mineral soils at Toolik Lake, Alaska. Potential activities of N-acetyl glucosaminidase, β-glucosidase, and peptidase tended to be greatest at the end of winter, suggesting that microbes produced enzymes while soils were frozen. In general, enzyme activities did not increase during the Arctic summer, suggesting that enzyme production is N-limited during the period when temperatures would otherwise drive higher enzyme activity in situ. We also detected seasonal variations in the temperature sensitivity ( Q10) of soil enzymes. In general, soil enzyme pools were more sensitive to temperature at the end of the winter than during the summer. We modeled potential in situβ-glucosidase activities for tussock and shrub organic soils based on measured enzyme activities, temperature sensitivities, and daily soil temperature data. Modeled in situ enzyme activity in tussock soils increased briefly during the spring, then declined through the summer. In shrub soils, modeled enzyme activities increased through the spring thaw into early August, and then declined through the late summer and into winter. Overall, temperature is the strongest factor driving low in situ enzyme activities in the Arctic. However, enzyme activity was low during the summer, possibly due to N-limitation of enzyme production, which would constrain enzyme activity during the brief period when temperatures would otherwise drive higher rates of decomposition. [ABSTRACT FROM AUTHOR]

Three new strains named LPA11, LPB11 and LPC24 were isolated to investigate the patterns of indole degradation and ammonia oxidation in swine wastewater from different parts of a swine wastewater treatment system by the direct spreading plate method. These three isolates were all identified as Pseudomonas putida based on 16S-rDNA gene sequences, main physiological and biochemical analysis. They were capable of decomposing 1.0mM indole completely in 10, 16 and 18 days respectively. According to the results of HPLC and GC/MS, the possible pathway for the degradation was via oxindole, isatin and anthranilic acid. The three bacteria were capable of oxidizing ammonia, and the strains LPA11 and LPC24 were capable of effectively reducing nitrate and nitrite. [ABSTRACT FROM AUTHOR]

Ultraviolet (UV) light irradiation, including the type of light source, light intensity, and irradiation dosage, directly affects the photocatalytic reaction rate and energy consumption. In this study, we investigated the photocatalysis effect of decomposing organic matter and inactivation bacteria and fungi under various conditions of UV sources (UVA and UVC) and light intensities (from 0.01 to 10 W/m²). The effect of light intensity was evaluated by photocatalytic reaction rate and UV dosage defined as a product of light intensity and irradiation time necessary to achieve a certain reduction. The results confirmed the positive effect of increased light intensity on photocatalytic reactions and suggested that within the light intensity range applied in this study low light intensity with long exposure time has higher light utilization efficiency compared to that of high light intensity with short exposure time. A conception for selection of the appropriate light intensity and dosage for effective degradation of pollutants, while saving energy, was provided. [ABSTRACT FROM AUTHOR]

1. The chemical composition of plant litter is commonly considered to indicate its quality as a resource for decomposer organisms. Litter quality, defined in this way, has been shown to be a major determinant of litter decomposition rates both within and across terrestrial ecosystems. Notably, the structure of the microbial community that is directly responsible for primary decomposition is rarely considered as an empirical predictor of litter decay rates. 2. Microbial communities are generally assumed to perceive litters of the same chemical composition to be of equivalent resource quality but evidence from field studies suggests that these same communities may adapt to the prevalent litter types at a given site. Here, we tested this assumption by assessing how microbial communities sourced from different forest- and herbaceous-dominated ecosystems perceive the quality of novel, foliar litters derived from a tree ( Rhododendron maximum) and from a grass ( Panicum virgatum) species. Based on chemical composition, we would expect R. maximum litter to be of lower quality than P. virgatum litter. 3. We used an experimental litter–soil system which employs a ‘common garden’ approach and measured rates of CO2 production across 50 days; higher rates of production were assumed to indicate higher quality (i.e. more easily degradable) litter. 4. We found that communities sourced from habitats under differing plant cover perceived litter quality differently. Those communities sourced from herbaceous habitats perceived the grass litter to be of higher quality than the tree litter, whereas communities from forest habitats decomposed both litter types similarly. Within a litter type, differences in both community composition and nutrient availability of the source habitat were related to decomposition rates. 5. Our results suggest that litter quality cannot necessarily be predicted solely from chemical characteristics; instead the perceived quality is dependent on the quality of past resource inputs a community has experienced and the structure of those microbial communities responsible for the initial stages of litter decomposition. [ABSTRACT FROM AUTHOR]

The article explores the environmental factors that stimulates the resistance in antibiotics. The author states that majority of the resistance was attributed the emergence of methicillin-resistance staphylococcus aureus (MRSA), a common bacterial agent with frightening consequences. He adds that the excreted drugs can persist in the environment, which create an opportunity for resistance selection within exposed bacterial populations. He also illustrates how antibiotics enter the environment and how resistance works.

The article discusses a study on the bioaerosol contamination in indoor and outdoor environments in Ankara, Turkey. It states that total bacteria counts (TBC) and fungi concentration are high in schools, restaurants and homes, while fungi levels are in kitchens, bathrooms and offices. It notes that bioaerosol exposure of indoor and outdoor environments can lead to health risks especially on children. It concludes that bacteria and fungi levels depend on the characteristics of the environment.

The article presents a study which examines the diuron-mineralizing potential of microbial communities at a small-scale watershed level using radiorespirometry. It notes the significant role of microbial communities which are adapted to pesticide biodegradation in reducing pesticide exposure in contaminated ecosystems. It suggests that rapid diuron mineralization requires the exposure of diuron to microbial communities. Furthermore, it stresses the potential role of grass strips in mineralization and attenuation of pesticides.

Arsenic is a redox-active metalloid whose toxicity and mobility strongly depends on its oxidation state, with arsenite (As(III)) being more toxic and mobile than arsenate (As(V)). Humic substances (HS) are also redox-active and can potentially react with arsenic and change its redox state. In this study we show that semiquinone radicals produced during microbial or chemical reduction of a HS model quinone (AQDS, 9,10-anthraquinone-2,6-disulfonic acid) are strong oxidants. They oxidize arsenate to arsenate, thus decreasing As toxicity and mobility. This reaction depends strongly on pH with more arsenite (up to 67.3%) being oxidized at pH 11 compared to pH 7 (12.6% oxidation) and pH 3 (0.5% oxidation). In addition to As(III) oxidation by semiquinone radicals, hydroquinones that were also produced during quinone reduction reduced As(V) to As(III) at neutral and acidic pH values (less than 12%) but not at alkaline pH. In order to understand redox reactions between arsenite/arsenate and reduced/oxidized HS, we quantified the radical content in reduced quinone solutions and constructed Eh-pH diagrams that explain the observed redox reactions. The results from this study can be used to better predict the fate of arsenic in the environment and potentially explain the occurrence of oxidized As(V) in anoxic environments. [ABSTRACT FROM AUTHOR]

Bacterial diversity and cell abundance in the snow of the four glaciers (Guoqu, Zadang, East Rongbuk and Palong No. 4) located in different climatic zones of the Tibetan Plateau were investigated through culture-independent molecular analysis of 16S rRNA gene clone library and flow cytometry approaches. Cell abundance ranged from 0.68 × 103 to 720 × 103 cells mL−1, with higher values in the northern glaciers than in the southern ones. Bacterial diversity was unexpectedly high in the snow habitats of the world’s highest plateau, with 15 common genera distributed widely among the glaciers. The bacterial diversity in the snow at different glaciers was related to the surrounding environments. The Guoqu Glacier, to the north near the desert zone and with the lowest temperature, preserved more bacteria closely related to a cold environment and soil than the other glaciers. However, in the Palong No. 4 Glacier located in the south warm region around vegetation, most bacteria were phylogenetically related to plant-associated bacteria. [ABSTRACT FROM AUTHOR]

Bacterial strains were isolated from endosulfan treated soil to study the microbial degradation of this pesticide in broth medium and soil microcosm. The isolates were grown in minimal medium and screened for endosulfan degradation. The strain, which utilized endosulfan and showed maximum growth, was selected for detail studies. Maximum degrading capability in shake flask culture was shown by Bordetella sp. B9 which degraded 80% of a endosulfan and 86% of β endosulfan in 18 days. Soil microcosm study was also carried out using this strain in six different treatments. Endosulfan ether and endosulfan lactone were the main metabolites in broth culture, while in soil microcosm endosulfan sulfate was also found along with endosulfan ether and endosulfan lactone. This bacterial strain has a potential to be used for bioremediation of the contaminated sites. [ABSTRACT FROM AUTHOR]

The article presents a study which uses a modified virus-dilution method in estimation of viral lysis and protozoan grazing on bacterial mortality. It compares modified virus-dilution method with the standard dilution protocol. It also aims to verify influence of the absence of lytic parameter in the standard protocol. Collected seawater samples from the coastal waters of Hokkaido, Japan were subjected to epifluorescence microscopy in the enumeration of microbes. It presents the advantages of modified virus-dilution technique synonymous to the standard dilution technique. It shows that the use of standard dilution protocol might underestimate instantaneous growth rate especially on pelagic systems where lytic pressure is relatively high.

Depth profiles of dimethylmercury (DMHg) concentration were determined at nearshore to offshore sites in Monterey Bay, California. The onset of spring upwelling in the bay was accompanied by increases in DMHg concentrations. Profiles show DMHg increasing gradually with depth in fall and winter from <0.03 pM at the surface to 0.5 pM at 200 m. During the spring, DMHg concentrations increased between 30 and 100 m, first within Monterey Bay, then offshore. This charge was accompanied by an increase in DMHg concentrations in the surface water DMHg between fall/winter (<0.03 pM) and spring (0.06-0.29 pM). Microbial activity associated with the remineralization of sinking organic matter produced by the high primary production in the bay may result in the relatively high DMHg in subsurface water in the bay, which when upwelled may facilitate the incorporation of organomercury into biota. As a result, productive coastal upwelling areas may represent an important source of methylated mercury to surface waters, and thus be an important source of mercury to marine ecosystems. [ABSTRACT FROM AUTHOR]

Dynamic dental instruments generate abundant aerosols in the work environment. Dental unit waterlines (DUWL) support a large microbial population and can be a significant source of bioaerosols generated during dental treatments. This study was conducted to characterize bioaerosol generation during dental treatments performed in standardized conditions. Culture-based method (R2A, and blood agar with and without O2) and fluorescence microscopy were used. Dental cleaning procedures were performed in an isolated treatment room with controlled ventilation rate. Andersen microbial samplers were used to collect culturable bioaerosols generated before (baseline), during, and after 2 hr of dental treatments. Inhalable dust samplers were used to measure total bioaerosols content in dental hygienist's and patients' breathing zones. AGI-30 were used for the collection of the endotoxin. The use of fluorescence microscopy in combination with culture demonstrated that dental staff and patients were exposed to up to 1.86 E+05 bacteria/m3 generated during treatments. Fortunately, bioaerosols returned to baseline within 2 hr after the dental procedures. The small diameter of the aerosols generated (<1 μm) suggests that the risk of contact between the aerosolized bacteria and the respiratory system of exposed individuals is likely to occur. [ABSTRACT FROM AUTHOR]

Abundance and seasonal dynamics of sulfate-reducing bacteria (SRB), in general, and of extreme halophilic SRB (belonging to Desulfocella halophila) in particular, were examined in highly saline industrial wastewater evaporation ponds over a forty one month period. Industrial wastewater was sampled and the presence of SRB was determined by quantitative real-time PCR (qPCR) with a set of primers designed to amplify the dissimilatory sulfite reductase (dsrA) gene. SRB displayed higher abundance during the summer (106-108 targets ml-1) and lower abundance from the autumn-spring (10³-105 targets ml-1). However, addition of concentrated dissolved organic matter into the evaporation ponds during winter immediately resulted in a proliferation of SRB, despite the lower wastewater temperature (12-14°C). These results indicate that the qPCR approach can be used for rapid measurement of SRB to provide valuable information about the abundance of SRB in harsh environments, such as highly saline industrial wastewaters. Low level of H2S has been maintained over five years, which indicates a possible inhibition of SRB activity, following artificial salination (≈16% w/v of NaCl) of wastewater evaporation ponds, despite SRB reproduction being detected by qPCR. [ABSTRACT FROM AUTHOR]

It is well established that the dissolved gaseous mercury (DGM) production in waters is mainly driven by photochemical processes. The present paper provides evidence for a significant bacteria-mediated DGM production, occurring also under dark conditions in environmentally different types of coastal water bodies of the Mediterranean basin. The DGM production was laboratory determined in sea, lagoon-brackish and lake water samples, comparing the efficiency of the DGM production processes in darkness and in the light. This latter condition was established by exposing samples at solar radiation intensity in the Photosyntetical Active Radiation region (PAR) of 200 W m−2. Mercury reduction rate in the dark was of the order of 2–4% of the DGM production in lightness, depending on the total mercury concentration in the water, rather than the bacterial abundance in it. Support for the active bacterial role in mercury reduction rate under dark conditions was provided by: 1) absence of significant DGM production in sterilized water samples (following filtration treatment or autoclaving), 2) restored DGM production efficiency, following re-inoculation into the same water samples of representatives of their bacterial community, previously isolated and separately cultured. Notwithstanding the low bacteria-mediated vs. the high photo-induced DGM production, whatever natural water body was considered, it is worth stressing the significant contribution of this organismal-mediated process to oceanic mercury evasion, since it occurs continuously along the entire water column throughout the 24 h of the day. [Copyright &y& Elsevier]

Soil bacteria regulate wetland biogeochemical processes, yet little is known about controls over their distribution and abundance. Bacteria in North Carolina swamps and bogs differ greatly from Florida Everglades fens, where communities studied were unexpectedly similar along a nutrient enrichment gradient. Bacterial composition and diversity corresponded strongly with soil pH, land use, and restoration status, but less to nutrient concentrations, and not with wetland type or soil carbon. Surprisingly, wetland restoration decreased bacterial diversity, a response opposite to that in terrestrial ecosystems. Community level patterns were underlain by responses of a few taxa, especially the Acidobacteria and Proteobacteria, suggesting promise for bacterial indicators of restoration and trophic status. [ABSTRACT FROM AUTHOR]

The article presents the study on the characterization of the toxic effects of cadmium (Cd) and 3.5-dichiorophenol (DCP) on nitrifying activity and mortality in biologically activated sludge systems. The study investigates the toxic impact of Cd and 3.5-DCP, being the representative of chemical substances commonly found in municipal sewage and industrial effluents and symbolize two different contaminant groups. The effects of Cd and 3.5-DCP on nitrification kinetics with respect to low temperature are also considered. Detailed results of the study are presented, showing the action mode of specific contaminants on nitrifying bacteria and the role of temperature.

The article discusses contributions the Medieval Spanish brought to the Western Hemisphere. The author talks about Spanish religious, military, and civil institutions brought to the West, as well as their material culture. The impact this material culture had on Texas is examined. Material culture discussed in the article includes domesticated plants, animals, and microbes. How these microbes changed Old World plants and domesticated animals is examined. The article also discusses how the Native Americans adopted to these changes and assimilated them into their own culture.

The article presents a study which examines the effects of the bacterial strain Exiguobacterium sp. ZM-2 for its resistance to hexavalent chromium which arises from released effluents from chrome tanning processes. It states that the study was undertaken for chromium reduction since chromium is considered as one of the most common polluting metals in soil. The study also utilized the atomic absorption spectrophotometer, plate dilution method, and the Cell Free Extract (CFE) as materias and methods of the study. Findings demonstrate that Exiguobacterium sp. ZM-2 could be exploited for remediation of soil and waste streams contaminated with hexavalent chromium.

Traditional culture-dependent methods to quantify and identify airborne microorganisms are limited by factors such as short-duration sampling times and inability to count non-culturable or non-viable bacteria. Consequently, the quantitative assessment of bioaerosols is often underestimated. Use of the real-time quantitative polymerase chain reaction (Q-PCR) to quantify bacteria in environmental samples presents an alternative method, which should overcome this problem. The aim of this study was to evaluate the performance of a real-time Q-PCR assay as a simple and reliable way to quantify the airborne bacterial load within poultry houses and sewage treatment plants, in comparison with epifluorescence microscopy and culture-dependent methods. The estimates of bacterial load that we obtained from real-time PCR and epifluorescence methods, are comparable, however, our analysis of sewage treatment plants indicate these methods give values 270–290 fold greater than those obtained by the “impaction on nutrient agar” method. The culture-dependent method of air impaction on nutrient agar was also inadequate in poultry houses, as was the impinger-culture method, which gave a bacterial load estimate 32-fold lower than obtained by Q-PCR. Real-time quantitative PCR thus proves to be a reliable, discerning, and simple method that could be used to estimate airborne bacterial load in a broad variety of other environments expected to carry high numbers of airborne bacteria. [Copyright &y& Elsevier]

Stable isotope fractionation analysis (SIFA) of contaminants is an emerging technique to characterize in situ microbial activity. The kinetic isotope effect in microbial degradation reactions, or enzyme catalysis, is caused by the preferential cleavage of bonds containing light rather than heavy isotopes. This leads to a relative enrichment of the heavier isotopes in the residual substrate pool. However, a number of nonisotopically sensitive steps preceding the isotopically sensitive bond cleavage may affect the reaction kinetics of a degradation process, thus reducing the observed (i.e., the macroscopically detectable) isotope fractionation. Low bioavailability of contaminants poses kinetic limitations on the biodegradation process and can significantly reduce the observed kinetic isotope fractionation. Here we present experimental evidence for the influence of bioavailability-limited pollutant biodegradation on observed stable isotope fractionation. Batch laboratory experiments were performed to quantify the toluene hydrogen isotope fractionation of Pseudomonas putida mt-2(pWWO) subjected to different small concentrations of toluene with and without deuterium label, which corresponded to realistic environmental mass transfer scenarios. Detected isotope fractionations depended significantly on the toluene concentration, hence confirming the influence of substrate mass transfer limitation on observed isotope fractionation, hypothesized by Thullner et al. (Environ. Sci. Technol. 2008, 42, 6544-6551). Our results indicate that the bioavailability of a substrate should be considered during quantitative analysis of microbial degradation based on SIFA. [ABSTRACT FROM AUTHOR]

Five stations were established in the Fenglin mangrove area of Xiamen, China to determine the concentrations of polycyclic aromatic hydrocarbons (PAHs) and the numbers of PAH-degrading bacteria in surface sediments. Assessing the biodegradation potential of indigenous microorganisms and isolating the high molecule weight (HMW)–PAH degrading bacteria was also one of the aims of this work. The results showed that the total PAH concentration of sediments was 222.59ngg−1 dry weight, whereas the HMW–PAH benzo(a)pyrene (BaP) had the highest concentration among 16 individual PAH compounds. The variation in the numbers of PAH-degrading bacteria was 2.62×102–5.67×104 CFUg−1 dry weight. The addition of PAHs showed a great influence in increasing the microbial activity in mangrove sediments. A bacterial consortium, which could utilize BaP as the sole source of carbon and energy, and which was isolated from mangrove sediments and enriched in liquid medium for nearly one year degraded 32.8% of BaP after 63 days incubation. [Copyright &y& Elsevier]

This report describes a twenty month case study of a successive alkalinity producing system (SAPS) treating a strong acid mine drainage (AMD) source in Coshocton County, Ohio. Prior to the commencement of the project, a large volume of black amorphous sludge had accumulated in several of the constructed wetlands. The sludge was found to be 43% organic, with very high concentrations of sulfur, iron, aluminum, and acidity. Based on several biological, physical, and chemical analyses, the sludge was determined to be an anaerobic biofilm with a large population of sulfur-reducing bacteria and a high mineral content due to the formation of iron sulfide and aluminum precipitates. On average the system performed well, generating 26 kg CaCO3/d of alkalinity and capturing 5.0 kg/d of iron and 1.7 kg/d of aluminum. Several simple performance analysis tools were presented in this work. By comparing the pollutant influent and effluent loading, it was determined that the SAPS was performing at capacity and over the past year increased effluent concentrations were due to increased influent loadings and not system deterioration. Further, by performing a detailed cell-by-cell loading analysis of multiple chemical components, the alkalinity generated by limestone dissolution and by sulfate reduction was determined. Interestingly, 61% of the alkalinity generation in the vertical flow wetlands was due to sulfur-reducing bacteria activity, indicating that sulfur-reducing bacteria may play a more significant role in SAPS than expected. [Copyright &y& Elsevier]

Batch experiments were conducted to investigate the kinetics of perchlorate reduction by heterotrophic and mixed perchlorate-reducing bacteria. Substrate-utilizing and cellular maintenance models were employed to fit the experimental data for microbial perchlorate reduction. The half saturation constant, K s, obtained in this study was below 0.1mg/L, which indicated that perchlorate-reducing bacteria are effective at utilizing low concentrations of perchlorate. The effect of pH on the kinetics of microbial perchlorate reduction was also studied. Perchlorate reduction occurred throughout the pH range from 5.0 to 9.0. Nevertheless, the rates of perchlorate removal by a unit mass of bacteria were significantly different at various pHs with a maximum rate at pH 7.0. The variation of q max with pH was described well with a Gaussian peak equation. This equation is expected to be applicable for practical purposes when pH effects need to be considered. [Copyright &y& Elsevier]

Trophic interactions and the relevance of the “classical” (CFW) versus the “microbial” (MFW) food webs were studied in the upwelling system of Antofagasta (23°S), northern Humboldt Current System (HCS) off Chile. Biological and ecological data gathered from the study area during 1996 and 1999–2002 and complementary data from the literature were analysed using the Ecopath with Ecosim software version 5.0 (EwE). The model includes the following functional groups: Detritus, dissolved organic matter (DOM), bacteria, phytoplankton, appendicularians, salps, calanoid copepods, cyclopoid copepods, chaetognaths, ctenophores, clupeiform fishes. The Antofagasta''s model indicate that only 18% of the total trophic relationships up to clupeiforms include only organisms of the CFW, while it is increased up to 82% when trophic relationships with organisms of the MFW are included. Removing the MFW from a complex, multi-level, trophic pathways, the energy transfer efficiency that characterise the study area either decreased or increased their value from detritus (from 14.4% to 13.6%) and primary production (from 11.0% to 15.1%), respectively. The total net primary production (PP) of the system with and without the MFW is similar (2.3grCm−2 d−1 and 2.2grCm−2 d−1), however, the total energy throughput increased in a system with MFW from ∼4.7grCm−2 d−1 to ∼9.8grCm−2 d−1. Thus, although the energy transfer efficiency is higher in a system without the MFW, the total system throughput is two times higher when it is considered. This might be due to (1) the inclusion of large new compartments in different trophic levels (such as DOM, bacteria), (2) the inclusion of the MFW would enhance the recycling of materials and energy and (3) the inclusion of new pathways such as bacteria – appendicularians/salps – anchovy (clupeiforms), that might produce a close link between the base of the microbial loop and clupeiforms, bypassing most of the MFW. The exclusion of the microbial loop from trophic models should strongly affect different planktonic groups such as salps, small cyclopoid copepods and appendicularians because they feed mainly (or partially, such as euphausiids) on small-size particles such as bacteria, microflagellates and ciliates. Thus, both CFW and MFW constitute highly complementary and interconnected trophic pathways from microbes up to fishes, and where more resolution at lower trophic level would be required to derive sensible model results that satisfactorily represent the system behaviour (i.e. ecosystem approach). [Copyright &y& Elsevier]

Eolian dispersion of mine tailings in arid and semiarid environments is an emerging global issue for which economical remediation alternatives are needed. Phytostabilization, the revegetation of these sites with native plants, is one such alternative. Revegetation often requires the addition of bulky amendments such as compost which greatly increases cost We report the use of plant growth-promoting bacteria (PGPB) to enhance the revegetation of mine tailings and minimize the need for compost amendment. Twenty promising PGPB isolates were used as seed inoculants in a series of greenhouse studies to examine revegetation of an extremely acidic, high metal contenttailings sample previously shown to require 15% compost amendment for normal plant growth. Several isolates significantly enhanced growth of two native species, quailbush and buffalo grass, in tailings. In this study, PGPB/compost outcomes were plant specific; for quailbush, PGPB were most effective in combination with 10% compost addition while for buffalo grass, PGPB enhanced growth in the complete absence of compost Results indicate that selected PGPB can improve plant establishment and reduce the need for compost amendment Further, PGPB activities necessary for aiding plant growth in mine tailings likely include tolerance to acidic pH and metals. [ABSTRACT FROM AUTHOR]

Loss of nitrogen from the soil-plant system has raised environmental concern. This study assessed the fluxes of nitrous oxide (N2O) in the subsurface flow constructed wetlands (CWs). To better understand the mechanism of N2O emission, spatial distribution of ammonia-oxidizing bacteria (AOB) in four kinds of wetlands soil were compared. N2O emission data showed large temporal and spatial variation ranging from −5.5 to 32.7mg N2Om−2 d−1. The highest N2O emission occurred in the cell planted with Phragmites australis and Zizania latifolia. Whereas, the lower emission rate were obtained in the cell planted with P. australis and Typha latifolia. These revealed that Z. latifolia stimulated the N2O emission. Transportation of more organic matter and oxygen for AOB growth may be the reason. The study of AOB also supported this result, indicating that the root structure of Z. latifolia was favored by AOB for N2O formation. [Copyright &y& Elsevier]

Abstract: Batch experiments were conducted to characterize the degradation of benzo[a]pyrene, a representative high molecular weight (HMW) polycyclic aromatic hydrocarbon (PAH), by Sphingomonas yanoikuyae JAR02. Concentrations up to the solubility limit (1.2μg l−1) of benzo[a]pyrene were completely removed from solution within 20h when the bacterium was grown on salicylate. Additional experiments with [14C]7-benzo[a]pyrene demonstrated 3.8% mineralization over 7days when salicylate was present is solution, and one major radio-labeled metabolite was observed that accounted for ∼10% of the initial radio-label. Further characterization of the radio-labeled metabolite using HPLC/MS and HPLC/MS/MS identified radio-labeled pyrene-8-hydroxy-7-carboxylic acid and unlabeled pyrene-7-hydroxy-8-carboxylic acid as novel ring-cleavage metabolites, and a benzo[a]pyrene degradation pathway was proposed. Results indicate that biostimulation of HMW PAH degradation by salicylate, a water-soluble, non-toxic substrate, has significant potential for in situ bioremediation. [Copyright &y& Elsevier]

For thousands of years wooden foundation piles have been widely used along coastal areas and river sites to stabilise urban settlements. Recent investigations, however, indicate that colonising bacteria can destroy the wood even below the groundwater level under low-oxygen conditions and cause severe strength loss over unexpectedly short periods. Existing knowledge of the species involved and the conditions required for growth of the bacteria is insufficient. The aim of this study was to characterise physicochemical site conditions by taking oxygen, redox potential, and chemical measurements at wooden foundation sites in Amsterdam, The Netherlands, that showed different decay intensities but had comparable sediment profiles. Oxygen (optode principle), redox potential (platinum electrodes), and groundwater table measurements were conducted biweekly over a year. Sediment solution was sampled every three months and analysed for pH, conductivity, total and dissolved carbon and nitrogen, NH4 +, NO3 −, SO4 2−, PO4 3−, Cl−, and major cations. Oxygen and redox measurements indicated oxygen-free conditions at both sites examined, but the water surrounding piles exhibited significantly higher total nitrogen concentrations at the site showing light decay. As other simultaneous investigations revealed a positive correlation between the nitrogen content in wooden pile samples and the decay intensities, we conclude that nitrogen might be a key factor in the decay process. We hypothesise that concentration gradients between sediment and wood matrix may control the decay intensity. [Copyright &y& Elsevier]

We investigated the relationship between wood degradation caused by erosion bacteria and the physicochemical properties of foundations with wooden piles from sites in the Netherlands, Germany, and Italy. Wooden foundation piles have been widely used to stabilise urban settlements along coastal areas and river sites for several millennia. Recently a number of these buildings have suffered from structural instability because their foundations have suddenly lost supporting strength. This loss of strength has been associated with the activity of erosion bacteria that can colonise and destroy wood under low-oxygen conditions, such as those that exist below the groundwater level. Knowledge of bacterial species involved in this process and their growth requirements is sparse, but it has been documented that the damage to wooden foundation piles caused by these bacteria can occur relatively rapidly. Redox potential (platinum electrodes) measurements, sediment, and sedimental water samples were obtained from nine European sites. Sediments were characterised and analysed for total contents of carbon, nitrogen, sulphur, phosphate, and major cations, whereas sedimental water was analysed for pH, conductivity, total and dissolved carbon and nitrogen, , , , , , and major cations. The chemical sediment composition was governed mainly by sediment type (sand, clay), whereas sediment water composition reflected the exposure to sea or freshwater and the redox status of the sampling location. Bacterial wood decay was detected at all sites but with different magnitude orders reflecting the different environments. When the physicochemical properties of sedimental water from foundations in sandy sediments were compared with wood degradation levels, it was observed that decreasing total nitrogen concentration, but not that of phosphate, accompanied increasing bacterial wood decay. [Copyright &y& Elsevier]

The identity of bacteria in waterlogged archaeological wood responsible for degradation was investigated using novel isolation techniques and molecular DNA technology. Wood in cultural heritage and archaeological sites is vulnerable to bacterial attack, with bacterially driven wood-decay predominating when wood is buried in sediments. In the research presented, DNA was extracted directly from wood samples and the diversity of bacterial species was determined. Using cultures isolated by project partners from archaeological wood of the same origin at 19 different European sites, a comparison of the DNA of nine culturable isolates and DNA from species commonly appearing in 56 independent molecular fingerprints was made. Results show that sequences representing bacteria from the Cytophaga-Flavobacterium-Bacteroides (CFB) complex and the Pseudomonas group were commonly recovered, with relatives of the Cellvibrio and Brevundimonas groups also present. These observations are the first to provide a molecular link between environmental samples where degradation had occurred and cultured organisms, although the precise role and capability of the bacterial strains remains obscure. [Copyright &y& Elsevier]

Lactobacillus reuteri ATCC 55730 is a probiotic strain that produces, in the presence of glycerol, reuterin, a broad-spectrum antimicrobial substance. This strain has been shown to prevent intestinal infections in vivo; however, its mechanisms of action, and more specifically whether reuterin production occurs within the intestinal tract, are not known. In this study, the effects of L. reuteri ATCC 55730 on intestinal microbiota and its capacity to secrete reuterin from glycerol in a novel in vitro colonic fermentation model were tested. Two reactors were inoculated with adult immobilized fecal microbiota and the effects of daily addition of L. reuteri into one of the reactors ( c.108 CFU mL−1) without or with glycerol were tested on major bacterial populations and compared with addition of glycerol or reuterin alone. The addition of glycerol alone or with L. reuteri increased numbers of the Lactobacillus–Enterococcus group and decreased Escherichia coli. The addition of reuterin significantly and selectively decreased E. coli without affecting other bacterial populations. The observed decrease in E. coli concentration during the addition of glycerol (in presence or absence of L. reuteri) could be due to in situ reuterin production because 1,3-propanediol, a typical product of glycerol fermentation, was detected during the addition of glycerol. [ABSTRACT FROM AUTHOR]

Abstract: Organotin compounds are used in a variety of industrial processes therefore their subsequent discharge into the environment is widespread. Bacteria play an important role in biogeochemical transformations acting as natural decontamination agents. Therefore, screening for (TBT)-resistant and -degrading bacteria is relevant for the selection of isolates with decontamination ability of these polluted areas. With this purpose, 50 strains were isolated from sediment and water from Ria de Aveiro and their tolerance to TBT, up to 3mM, was evaluated. Generally, occurrence of highly TBT-resistant bacteria was observed, and Gram negative bacteria exhibited more tolerance to TBT than Gram positive bacteria. A memory response was observed when bacteria were progressively exposed to increasingly higher TBT concentrations. One isolate, Aeromonas veronii Av27, highly resistant to TBT (3mM) uses this compound as carbon source and degrades it to less toxic compounds. [Copyright &y& Elsevier]

The article discusses the biochemical and physiological implications of butane monooxygenase activity in pseudomonas butanovora. Bacterial monooxygenase enzymes are broadly studied for its potential to help degrade environmental pollutants. It also serves as a biocatalysts for the creation of important chemicals for industrial purposes. Pseudomonas Butanovora cultivates with butane through the oxidation of butane to 1- butanol. This is done through a soluble butane monooxygenase. A supposed model is presented that tries to explain propionate- dependent inactivation with the butane monooxygenase when applied to the soluble methane monooxygenase.

The study was conducted by a novel salt tolerant bacterium Gracilibacillus sp. GTY. The strain was identified on the basis of morphological and physio-biochemical characteristics, and 16S rDNA sequence analysis. Decolorization was performed by growing and resting cells, as well as by extracted azo reductase. Strain grown in the media containing 15% (w/v) of NaCl showed the best performance in decolorization. Decolorization was observed by the UV–visible absorbance spectra. The maximum absorption peak in the visible area decreased to a minimum level after 96 h of incubation. On the other hand, strain grown in very low, or high concentrations, of salt did not show good performance in decolorization; suggesting that salt concentrations in the surroundings control the production of azo reductase. [ABSTRACT FROM AUTHOR]

In situ bioremediation is a safe and cost-effective technology for the cleanup of organic-contaminated soil, but its remediation rate is usually very slow, which results primarily from limited mass transfer of pollutants to the degrading bacteria in soil media. This study investigated the feasibility of adopting 2D non-uniform electric field to enhance in situ bioremediation process by promoting the mass transfer of organics to degrading bacteria under in situ conditions. For this purpose, a 2D non-uniform electrokinetic system was designed and tested at bench-scale with a sandy loam as the model soil and 2,4-dichlorophenol (2,4-DCP) as the model organic pollutant at two common operation modes (bidirectional and rotational). Periodically, the electric field reverses its direction at bidirectional mode and revolves a given angle at rotational mode. The results demonstrated that the non-uniform electric field could effectively stimulate the desorption and the movement of 2,4-DCP in the soil. The 2,4-DCP was mobilized through soil media towards the anode at a rate of about 1.0cmd−1 V−1. The results also showed that in situ biodegradation of 2,4-DCP in the soil was greatly enhanced by the applied 2D electric field upon operational mode. At the bidirectional mode, an average 2,4-DCP removal of 73.4% was achieved in 15 days, and the in situ biodegradation of 2,4-DCP was increased by about three times as compared with that uncoupled with electric field, whereas, 34.8% of 2,4-DCP was removed on average in the same time period at the rotational mode. In terms of maintaining remediation uniformity in soil, the rotational operation remarkably excelled the bidirectional operation. In the hexagonal treatment area, the 2,4-DCP removal efficiency adversely increase with the distance to the central electrode at the bidirectional mode, while the rotational mode generated almost uniform removal in soil bed. [Copyright &y& Elsevier]

The genus Carnobacterium contains nine species, but only C. divergens and C. maltaromaticum are frequently isolated from natural environments and foods. They are tolerant to freezing/thawing and high pressure and able to grow at low temperatures, anaerobically and with increased CO2 concentrations. They metabolize arginine and various carbohydrates, including chitin, and this may improve their survival in the environment. Carnobacterium divergens and C. maltaromaticum have been extensively studied as protective cultures in order to inhibit growth of Listeria monocytogenes in fish and meat products. Several carnobacterial bacteriocins are known, and parameters that affect their production have been described. Currently, however, no isolates are commercially applied as protective cultures. Carnobacteria can spoil chilled foods, but spoilage activity shows intraspecies and interspecies variation. The responsible spoilage metabolites are not well characterized, but branched alcohols and aldehydes play a partial role. Their production of tyramine in foods is critical for susceptible individuals, but carnobacteria are not otherwise human pathogens. Carnobacterium maltaromaticum can be a fish pathogen, although carnobacteria are also suggested as probiotic cultures for use in aquaculture. Representative genome sequences are not yet available, but would be valuable to answer questions associated with fundamental and applied aspects of this important genus. [ABSTRACT FROM AUTHOR]

Abstract: Burkholderia cepacia is regarded as a genetically distinct but phenotypically similar bacteria group referring to Burkholderia cepacia complex (Bcc), which is found not only in clinic but also in rice growing environment. It is very important in microbial safety of rice for us to understand the genomovar status of Bcc. Genomovar analysis was performed among 87 Bcc isolates by means of Hae ?-recA RFLP assays and species-specific PCR tests. Three genomovars were found from the rice rhizosphere including?, ?B and ?, and genomovar ? was predominant. Genomovars?, ?A and ?B existed in the clinical samples, and genomovar ?A was the most popular. It showed that genomovar composition was different between the Bcc strains from the rice rhizosphere and clinical environment. Simultaneously, the results revealed the genetic diversity of Bcc strains from the rice rhizosphere, and genomovar ? referred as virulent species in clinic also existed in the rice rhizosphere. [Copyright &y& Elsevier]

Seven strains that can degrade nitrobenzene at low temperature were isolated from the sediments of a nitrobenzene-polluted river. One of the strains, NB-1, can mineralize 20 mg/L nitrobenzene completely from 2.5 to 35°C with an optimum temperature of 25°C. NB-1 was identified as Pseudomonas putida according to its morphology, biochemical properties, and 16S rDNA sequence analysis. The strain could tolerate and degrade 120 mg/L nitrobenzene within 175 h at 5°C. It can be used for the bioremediation of nitrobenzene-contaminated environment. [ABSTRACT FROM AUTHOR]