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Sulfamethoxazole (SMX) is a widespread and persistent pollutant in the environment. Although the screening and analysis of SMX-degrading bacteria have been documented, the interaction mechanisms of functional microorganisms are still poorly understood. This study constructed a consortium with strain YL1 and YL2 supplied with SMX as the sole carbon and energy source. The coexisting mechanism and the removal of SMX of the consortium were investigated. The total oxidizable carbon (TOC) removal rate of the combined bacterial system was 38.94% compared to 29.45% for the single bacterial system at the same biomass. The mixed bacterial consortium was able to resist SMX at concentrations up to 400 mg/L and maintained a stable microbial structure at different culture conditions. The optimum conditions found for SMX degradation were 30 °C, pH 7.0, a shaking speed of 160 r·min−1, and an initial SMX concentration of 200 mg·L−1. The degradation of SMX was accelerated by the addition of YL2 for its ability to metabolize the key intermediate, 4-aminophenol. The removal rate of 4-aminophenol by strain YL2 reached 19.54% after 5 days. Genome analysis revealed that adding riboflavin and enhancing the reducing capacity might contribute to the degradation of SMX. These results indicated that it is important for the bioremediation of antibiotic-contaminated aquatic systems to understand the metabolism of bacterial communities. [ABSTRACT FROM AUTHOR]

Biosurfactants from Pseudomonas spp. have been reported to exhibit antibacterial and anti-adhesive properties, but their role during meat spoilage remains unclear. In this study, the biosurfactant was isolated from an isolate of Pseudomonas fragi with strong spoilage potential, and its surface tension and emulsification ability were determined. The chemical and microbial characteristics of the biosurfactant-treated meat samples were periodically analyzed. The results demonstrated that the biosurfactant produced by P. fragi could reduce surface tension and showed good emulsification properties. For the in situ spoilage trials, biosurfactant from P. fragi changed the microbial diversity on meat, helping Pseudomonas establish a dominant position in the population. However, biosurfactant treatment caused chicken meat to exhibit a weaker spoilage state, as indicated by the growth of psychrophilic microorganisms, total volatile basic nitrogen (TVBN) and meat color. These results provide practical information for understanding the role of P. fragi biosurfactant during chilled meat storage. • Biosurfactant was isolated from a strain of meat-borne Pseudomonas fragi. • Biosurfactant can reduce the surface tension and exhibit good emulsification ability. • Biosurfactant can promote the dominance of Pseudomonas in the bacterial community. • Biosurfactant-treatment weakened the spoilage state of chilled meat. [ABSTRACT FROM AUTHOR]

Extracellular polymeric substances (EPS) play an important role in bacterial biochemical properties. The characteristics of EPS from 2 strains of Pseudomonas fragi cultured in meat aerobically (control) and in modified atmosphere packaging (MAP) were studied. The amount and components of EPS, the surface properties, and the effect on biofilm formation of several spoilage organisms were evaluated. The results showed that MAP inhibited the growth of the P. fragi strains. Compared with the control, more loose and less bound EPS (containing protein and carbohydrate) were produced by P. fragi in MAP samples. MAP also caused increased cell autoaggregation and surface hydrophobicity. After the removal of the EPS, the surface property changes were strain-dependent, suggesting that membrane compositions were also changed. In addition, the EPS displayed significant antibiofilm activity on Pseudomonas fluorescens and Serratia liquefaciens. In conclusion, P. fragi strains not only modified the amount, components, and surface properties of EPS but also changed the cell membrane compositions to adapt to MAP stress. Moreover, EPS may play an important role in microbial community competitions. [ABSTRACT FROM AUTHOR]

The effect of nitrite on autotrophic denitrification was tested using mixed electron donors of Mn(II) and Fe(II) with Pseudomonas sp. SZF15. In batch experiments, nitrate and nitrite were completely depleted without ammonia production (denitrification rate of 0.151 mg-NO3−-N·L−1·h−1 and 0.104 mg-NO2−-N·L−1·h−1, respectively), suggesting that denitrification occurred by strain SZF15 via nitrite reductase. A maximum denitrification rate of 0.097 mg-NOX−-N·L−1·h−1 was found at an n(NO3−-N):n(NO2−-N) ratio of 5:5. Edwards and Aiba models were used to describe the denitrification inhibition caused by nitrite, and the kinetic parameters determined from the Edwards model were rmax of 2.148 mg-NO2−-N·g-VSS−1·h−1, KS of 6.225 mg-NO2−-N·L−1, and KI of 25.152 mg-NO2−-N·L−1. These results provide useful information for optimization of the autotrophic denitrification process by avoiding inhibition to obtain higher denitrification efficiencies. In addition, strain SZF15 showed excellent denitrification performance for groundwater treatment. [ABSTRACT FROM AUTHOR]

An aerobic denitrification system, initially bioaugmented with Pseudomonas strain T13, was established to treat coal-based ethylene glycol industry wastewater, which contained 3219 ± 86 mg/L total nitrogen (TN) and 1978 ± 14 mg/L NO -N. In the current study, a stable denitrification efficiency of 53.7 ± 4.7% and nitrite removal efficiency of 40.1 ± 2.7% were achieved at different diluted influent concentrations. Toxicity evaluation showed that a lower toxicity of effluent was achieved when industry wastewater was treated by stuffing biofilm communities compared to suspended communities. Relatively high TN removal (~50%) and chemical oxygen demand removal percentages (>65%) were obtained when the influent concentration was controlled at below 50% of the raw industry wastewater. However, a further increased concentration led to a 20-30% decrease in nitrate and nitrite removal. Microbial network evaluation showed that a reduction in Pseudomonas abundance was induced during the succession of the microbial community. The napA gene analysis indicated that the decrease in nitrate and nitrite removal happened when abundance of Pseudomonas was reduced to less than 10% of the overall stuffing biofilm communities. Meanwhile, other denitrifying bacteria, such as Paracoccus, Brevundimonas, and Brucella, were subsequently enriched through symbiosis in the whole microbial network. [ABSTRACT FROM AUTHOR]

Strain H117 was isolated from the Tang Yu reservoir. Based on the phylogenetic characteristics, strain H117, which was identified as Pseudomonas sp. strain H117, had the capability to utilize bicarbonate and sodium acetate as a carbon source under anaerobic conditions. Furthermore, the strain could grow on both autotrophic and heterotrophic media, and could perform both autotrophic and heterotrophic denitrification in the medium. Response surface methodology analysis demonstrated that the maximum degradation ratio of nitrate-occurred under the following conditions in the autotrophic medium: initial pH of 6.00, C/N ratio of 4.68 and temperature of 31.33°C. The maximum degradation ratio of nitrate occurred under the following conditions in the heterotrophic medium: initial pH of 6.16, C/N ratio of 8.23 and temperature of 28.48°C. Finally, the denitrification performance of strain H117 was evaluated under the optimum conditions. These results suggest that strain H117 has potential applications for the bioremediation of polluted groundwater. [ABSTRACT FROM AUTHOR]

Pseudomonassp. is a common kind of bacteria. In order to confirm whetherPseudomonassp. can be used to remove the heavy metals from wastewater, the study investigated its adsorption capacity in single and Cu2+–Ni2+binary systems. Experimental parameters affecting the metal uptake byPseudomonassp. in single system, such as initial solution pH, initial metal concentration, and contact time, were investigated. In single system, the highest adsorption yields of Cu2+and Ni2+by thePseudomonassp. were 44.78 mg Cu2+ g−1and 336.84 mg Ni2+ g−1, respectively, at the optimum conditions for each metal. The kinetic and equilibrium experimental data of Cu2+and Ni2+ions in the single systems could be successfully described by Langmuir and Freundlich isotherms, whereas the adsorption isotherm was better described by a Langmuir model rather than a Freundlich model. In Cu2+–Ni2+binary systems, the maximum adsorption amount of Cu2+and Ni2+were 38.62 mg Cu2+ g−1and 323.47 mg Ni2+ g−1, respectively. It obviously showed that the adsorption capacities of the two ions were suppressed, and nickel ion was dominant in the competitive adsorption. Besides, the equilibrium data for the interaction of the metal ions in the binary system could well be described by the Langmuir competitive model. The result gained from these studies indicated thatPseudomonassp. had the potential to remove Cu2+and Ni2+ions from wastewaters. [ABSTRACT FROM PUBLISHER]

[Display omitted] • AprD-mediated metabolic reprogramming in meat-borne P. fragi was studied. • The biofilm architecture varied greatly due to the absence of aprD. • The aprD deletion triggered the alterations of three cellular metabolic pathways. • AprD was critical for regulating cell metabolism and spoilage strength of P. fragi. Pseudomonas fragi is by far one of the most threatening species in the spoilage of chilled meat that is stored under aerobic conditions. The membrane protein AprD is a well-established regulator controlling protease secretion in Pseudomonas spp. However, its exact roles in modulating metabolic pathways and spoilage potential of P. fragi at the molecular level remain undefined. Here, an in-frame deletion mutation of aprD was used to explore the impacts on their biofilm structure, matrix secretion, and cell metabolism. The results showed that Δ aprD formed relatively disorganized loose aggregation in biofilm, resulting in a thinner structure and more dead cells. Meanwhile, marked changes in the content of extracellular carbohydrates and proteins were observed. Furthermore, intracellular metabolomic profiling revealed the involvement of aprD in several cellular metabolic pathways, mostly including the carbohydrate pathway, amino acid pathway, and nucleotide pathway, while the characterization of extracellular metabolism clarified the variations in the spoilage-related metabolites (e.g., creatine, IMP, spermine, fatty acids, amino acids, and oligopeptides) could be highly correlated with aprD deletion. In this finding, we indicated that aprD could be responsible for cell reproduction and in situ spoilage potential of P. fragi NMC25 during chilled storage by controlling related metabolism and nutrients utilization. Thus, our results will contribute to an improved understanding of the regulatory mechanism of aprD gene in meat spoilage contaminated with P. fragi , which can be valuable to ensure the quality and safety of meat. [ABSTRACT FROM AUTHOR]

Sulfamethoxazole is a common antibiotic that is frequently detected in wastewater and surface water. This study investigated the biodegradation and metabolic pathway of sulfamethoxazole by Pseudomonas psychrophila HA-4, a cold-adapted bacterium. Strain HA-4, which uses sulfamethoxazole as its sole source of carbon and energy, was isolated at a low temperature (10 °C) and identified as P. psychrophila by physico-biochemical characterization and 16S rRNA gene sequence analysis. Strain HA-4 removed sulfamethoxazole at temperatures ranging from 5.0 °C to 30 °C, with the maximal removal rate at 10 °C. The maximal removal rate of sulfamethoxazole by strain HA-4 was 34.30 % after 192 h at 10 °C. The highest percentage of unsaturated fatty acid was determined to be 23.03 % at 10 °C, which adheres to the characteristic for cold-adapted psychrophiles and psychrotrophs. At low concentrations of sulfamethoxazole, the growth kinetics correlated well with the Haldane model. The single-substrate parameter values of sulfamethoxazole on cell growth were determined to be μ = 0.01 h, K = 20.91 mg/l and K = 170.60 mg/l. Additionally, the major intermediates from sulfamethoxazole biodegradation by strain HA-4, including aniline, 3-amino-5-methylisoxazole, 4-aminothiophenol and sulfanilamide, were identified by GC-MS and high-resolution mass spectrometry (HR-MS) analysis. The results demonstrate that strain HA-4 has the potential to degrade sulfamethoxazole at low temperatures. [ABSTRACT FROM AUTHOR]

Abstract: The composition and dynamics of sulfate-reducing bacteria (SRB) during the waterflooding process of Daqing Oilfield were investigated in this study. PCR–DGGE analysis indicated that the microbial communities were significantly different in each treatment unit, and the dominant members were mainly close to Clostridium sp., Thauera sp., Hydrogenophaga sp., Pseudomonas sp., Eubacterium sp. and Arcobacter sp. However, the members belonging to SRB were relatively few and mainly consisted of Desulfovibrio sp. and Desulfovibrio profundus. According to APS (adenosine-5′-phosphosulfate reductase) gene clone library and sequence analysis, it was found that SRB mainly belonged to Proteobacteria and Deltaproteobacteria. In the library, the genus Desulfovibrio of Deltaproteobacteria was about 65.2% while genus Desulfomonas, Desulfomicrobium, Desulfohalobium, Desulfonatronum, Desulfbulbus, Desulforhopalus, Desulfnema and Desulforhopalus were occupied nearly 34.8%. It was also proved that most of SRB in the oil field were enriched in the ground treatment unit and they are not in the liquid of oil well. [Copyright &y& Elsevier]

Atrazine, a widely used herbicide, is increasing the agricultural production effectively, while also causing great environmental concern. Efficient atrazine-degrading bacterium is necessary to removal atrazine rapidly to keep a safe environment. In the present study, a new atrazine-degrading strain ZXY-1, identified as Pseudomonas , was isolated. This new isolated strain has a strong ability to biodegrade atrazine with a high efficiency of 9.09 mg/L/hr. Temperature, pH, inoculum size and initial atrazine concentration were examined to further optimize the degradation of atrazine, and the synthetic effect of these factors were investigated by the response surface methodology. With a high quadratic polynomial mathematical model ( R 2 = 0.9821) being obtained, the highest biodegradation efficiency of 19.03 mg/L/hr was reached compared to previous reports under the optimal conditions (30.71°C, pH 7.14, 4.23% ( V/V ) inoculum size and 157.1 mg/L initial atrazine concentration). Overall, this study provided an efficient bacterium and approach that could be potentially useful for the bioremediation of wastewater containing atrazine. [ABSTRACT FROM AUTHOR]

Combined bioelectrochemical and sulfur autotrophic denitrification (CBSAD) system had proven to be feasible for nitrate removal at low temperature. This system obtained excellent denitrification efficiency 96.55% at 10 ± 2 °C long term operation. Nitrate removal efficiency presented increased tendency with applied current increased from 50 to 200 mA and then decreased when the applied current was further increased to 300 mA. The CBSAD system owned the most abundant and rich communities at current 200 mA, and the community structures of the microbial samples at different current conditions were clearly different from each other. Phyla Firmicutes , Proteobacteria and classes Epsilonproteobacteria , Gammaproteobacteria , Betaproteobacteria , Clostridia dominated in all the communities in the system. The largest genus at current 50 mA was Arcobacter , whereas Pseudomonas was the most dominant genus at current 100–300 mA condition, suggesting that high current changed the bacterial structure in this CBSAD reactor. [ABSTRACT FROM AUTHOR]

Carbamazepine is frequently detected in waters and hardly eliminated during conventional wastewater treatment processes due to its complicated chemical structure and resistance to biodegradation. A carbamazepine-degrading bacterium named CBZ-4 was isolated at a low temperature (10°C) from activated sludge in a municipal wastewater treatment plant. Strain CBZ-4, which can use carbamazepine as its sole source of carbon and energy, was identified as Pseudomonas sp. by the 16S rRNA gene sequence. The composition and percentage of fatty acids, which can reveal the cold-adaptation mechanism of strain CBZ-4, were determined. Strain CBZ-4 can effectively degrade carbamazepine at optimal conditions: pH 7.0, 10°C, 150 r/min rotation speed, and 13% inoculation volume. The average removal rate of carbamazepine was 46.6% after 144 hr of incubation. The biodegradation kinetics of carbamazepine by CBZ-4 was fitted via the Monod model. V max and K s were found to be 0.0094 hr −1 and 32.5 mg/L, respectively. [ABSTRACT FROM AUTHOR]

Abstract: A novel meta-fission product hydrolase gene (mfphA) located in the bphX gene region of Dyella ginsengisoli LA-4 was successfully cloned and heterologously expressed in this study. The deduced amino acid sequence of MfphA showed 75% identity with the sequence of 2-hydroxymuconic semialdehyde hydrolase from Pseudomonas putida UCC22. The results suggested that MfphA belonged to the α/β hydrolase family, which could hydrolyze the meta-fission products (MFPs) during the biodegradation process of monocyclic compounds. The His-Tag MfphA was purified, and the subunit molecular mass of MfphA was about 35.3kDa by SDS-PAGE analysis. According to the apparent kinetic parameters, the specificity of MfphA was determined in the following order: 6-methyl-HODA>HODA>5-methyl-HODA>6-phenyl-HODA>5-chloro-HODA (HODA, 2-hydroxy-6-oxohexa-2,4-dienoate). The activity of MfphA for HODA was higher than that for 6-methyl-HODA. It was shown that the maximum activity was at 70°C, and MfphA was stable for storage at low temperature for 30 days. [Copyright &y& Elsevier]

Pseudomonas fragi is a common spoilage agent of aerobically stored chilled meat. Its extracellular protease contributes to the spoilage of meat. AprD is considered an important component involved in the secretion of an alkaline extracellular protease in Pseudomonas. Thus, it is very possible that aprD plays an important role in spoilage regulation in P. fragi. The objective of the present study was to investigate the effects of aprD on bacterial proteolytic activity, biological properties, and in situ spoilage potential, as well as the mode of action of the protease AprA in spoiled meat. The results showed that aprD is important for surface-associated behaviors, as an Δ aprD mutant altered autoaggregation, swimming motility, and biofilm formation. aprD also contributes to the spoilage activities of P. fragi by affecting extracellular protease activity, total volatile basic nitrogen production, pH and the sensory traits of meat samples. These results highlight the presence of aprD -mediated regulation profiles in P. fragi and may provide new perspectives on chilled meat preservation. • AprD mediated the secretion of the only protease in P. fragi. • AprD inversely affected the swimming motility and biofilm formation of P. fragi. • AprD contributed to the in situ spoilage potential of P. fragi. • Slime and off-odor occurred during meat spoilage came from not only aprD -mediated proteolytic activity. [ABSTRACT FROM AUTHOR]