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Canadian Journal of Microbiology Feb 2021The SCUEC4 strain of is a newly isolated bacterium that degrades nicotine can use nicotine as the sole carbon source via a series of enzymatic catalytic processes. The...
The SCUEC4 strain of is a newly isolated bacterium that degrades nicotine can use nicotine as the sole carbon source via a series of enzymatic catalytic processes. The mechanisms underlying nicotine degradation in this bacterium and the corresponding functional genes remain unclear. Here, we analyzed the function and biological properties of the gene involved in the nicotine-degradation pathways in strain SCUEC4. The gene was cloned by PCR with total DNA of strain SCUEC4 and used to construct the recombinant plasmid pET28a-. The overexpression of the OcnE protein was detected by SDS-PAGE analysis, and study of the function of this protein was spectrophotometrically carried out by monitoring the changes of 2,5-dihydroxypyridine. Moreover, the effects of temperature, pH, and metal ions on the biological activities of the OcnE protein were analyzed. The optimal conditions for the biological activities of OcnE, a protein of approximately 37.6 kDa, were determined to be 25 °C, pH 7.0, and 25 μmol/L Fe, and the suitable storage conditions for the OcnE protein were 0 °C and pH 7.0. In conclusion, the gene is responsible for the ability of 2,5-dihydroxypyridine dioxygenase. These findings will be beneficial in clarifying the mechanisms of nicotine degradation in SCUEC4.
Topics: Bacterial Proteins; Genes, Bacterial; Hydrogen-Ion Concentration; Iron; Molecular Weight; Nicotine; Ochrobactrum; Pyridines; Recombinant Proteins; Temperature
PubMed: 32841574
DOI: 10.1139/cjm-2020-0118 -
Zoonoses and Public Health Sep 2020Increase in the number of small-scale backyard poultry flocks in the USA has substantially increased human-to-live poultry contact, leading to increased public health...
The occurrence of Salmonella, extended-spectrum β-lactamase producing Escherichia coli and carbapenem resistant non-fermenting Gram-negative bacteria in a backyard poultry flock environment.
Increase in the number of small-scale backyard poultry flocks in the USA has substantially increased human-to-live poultry contact, leading to increased public health risks of the transmission of multi-drug resistant (MDR) zoonotic and food-borne bacteria. The objective of this study was to detect the occurrence of Salmonella and MDR Gram-negative bacteria (GNB) in the backyard poultry flock environment. A total of 34 backyard poultry flocks in Washington State (WA) were sampled. From each flock, one composite coop sample and three drag swabs from nest floor, waterer-feeder, and a random site with visible faecal smearing, respectively, were collected. The samples were processed for isolation of Salmonella and other fermenting and non-fermenting GNB under ceftiofur selection. Each isolate was identified to species level using MALDI-TOFF and tested for resistance against 16 antibiotics belonging to eight antibiotic classes. Salmonella serovar 1,4,[5],12:i:- was isolated from one (3%) out of 34 flocks. Additionally, a total of 133 ceftiofur resistant (Cef ) GNB including Escherichia coli (53), Acinetobacter spp. (45), Pseudomonas spp. (22), Achromobacter spp. (8), Bordetella trematum (1), Hafnia alvei (1), Ochrobactrum intermedium (1), Raoultella ornithinolytica (1), and Stenotrophomonas maltophilia (1) were isolated. Of these, 110 (82%) isolates displayed MDR. Each flock was found positive for the presence of one or more Cef GNB. Several MDR E. coli (n = 15) were identified as extended-spectrum β-lactamase (ESBL) positive. Carbapenem resistance was detected in non-fermenting GNB including Acinetobacter spp. (n = 20), Pseudomonas spp. (n = 11) and Stenotrophomonas maltophila (n = 1). ESBL positive E. coli and carbapenem resistant non-fermenting GNB are widespread in the backyard poultry flock environment in WA State. These GNB are known to cause opportunistic infections, especially in immunocompromised hosts. Better understanding of the ecology and epidemiology of these GNB in the backyard poultry flock settings is needed to identify potential risks of transmission to people in proximity.
Topics: Aged; Animal Husbandry; Animals; Anti-Bacterial Agents; Carbapenems; Chickens; Child, Preschool; Drug Resistance, Multiple, Bacterial; Escherichia coli; Escherichia coli Infections; Gene Expression Regulation, Bacterial; Gene Expression Regulation, Enzymologic; Gram-Negative Bacteria; Gram-Negative Bacterial Infections; Housing, Animal; Humans; Salmonella; Salmonella Infections, Animal; Surveys and Questionnaires; beta-Lactamases
PubMed: 32710700
DOI: 10.1111/zph.12756 -
Frontiers in Microbiology 2020Quorum quenching (QQ) is a promising strategy for preventing and controlling quorum sensing (QS)-mediated bacterial infections. It interferes with QS by the inhibition...
Quorum quenching (QQ) is a promising strategy for preventing and controlling quorum sensing (QS)-mediated bacterial infections. It interferes with QS by the inhibition of signal synthesis, the detection of enzyme-catalyzed degradation, and the modification of signals. -Acyl homoserine lactones (AHLs) represent a family of widely conserved QS signals involved in the regulation of virulence factor production in many Gram-negative bacterial pathogens. In this study, AHL-degrading bacterial strains were isolated, and the most efficient one was evaluated for its potential against QS-mediated pathogens. Results showed that an AHL-degrading bacteria D-2 effectively attenuated maceration produced by the pathogen subsp. (Pcc) on radish and potato slices. Strain D-2 exhibited a superior AHL degradation activity and efficiently degraded various AHLs, including -hexanoyl-L-homoserine lactone (C6HSL), -(3-oxohexanoyl)-L-homoserine lactone (3OC6HSL), -(3-oxooctanoyl)-L-homoserine lactone (3OC8HSL), and -(3-oxododecanoyl)-L-homoserine lactone (3OC12HSL). Analysis of the degradation products of AHL by gas chromatography-mass spectrometry led to the identification of -cyclohexyl-propanamide and propanamide as the main intermediate products, suggesting that AHL was degraded by hydrolysis. Annotation and analysis of the whole genome sequence of strain D-2 revealed the presence of an AHL-lactonase, termed AidF. Moreover, the application of strain D-2 was able to substantially reduce the disease severity caused by Pcc on host plants. These results reveal the biochemical basis of a highly efficient AHL-degrading bacterial isolate and present the potential to attenuate Pcc virulence through QQ.
PubMed: 32457732
DOI: 10.3389/fmicb.2020.00898 -
Poultry Science Apr 2020This study was conducted to investigate the effects of dietary arginine (Arg) supplementation on the inflammatory response and gut microbiota of broiler chickens...
Dietary l-arginine supplementation ameliorates inflammatory response and alters gut microbiota composition in broiler chickens infected with Salmonella enterica serovar Typhimurium.
This study was conducted to investigate the effects of dietary arginine (Arg) supplementation on the inflammatory response and gut microbiota of broiler chickens subjected to Salmonella enterica serovar Typhimurium. One hundred and forty 1-day-old Arbor Acres male birds were randomly assigned to a 2 × 2 factorial arrangement including diet treatment (with or without 0.3% Arg supplementation) and immunological stress (with or without S. typhimurium challenge). Samples were obtained at 7 D after infection (day 23). Results showed that S. typhimurium challenge caused histopathological and morphological damages, but Arg addition greatly reduced these intestinal injuries. S. typhimurium challenge elevated the levels of serum inflammatory parameters, including diamine oxidase, C-reactive protein, procalcitonin, IL-1β, IL-8, and lipopolysaccharide-induced tumor necrosis factor-alpha factor (LITNF) homolog. However, Arg supplementation decreased the serum procalcitonin, IL-1β, IL-8, and LITNF concentration. S. typhimurium challenge significantly increased jejunal IL-1β, IL-8, IL-10, and IL-17 mRNA expression and tended to upregulate IL-22 mRNA expression, but Arg supplementation remarkably reduced IL-8 mRNA expression, tended to downregulate IL-22 mRNA expression, and dramatically elevated IFN-γ and IL-10 mRNA expression. In addition, sequencing data of 16S rDNA indicated that the population of Proteobacteria phylum; Enterobacteriaceae family; Escherichia-Shigella, and Nitrosomonas genera; and Escherichia coli and Ochrobactrum intermedium species were more abundant, but the population of Rhodocyclaceae and Clostridiaceae_1 families and Candidatus Arthromitus genus were less abundant in the ileal digesta of birds with only S. typhimurium infection when compared with the controls. Treatment with Arg in birds subjected to S. typhimurium challenge increased the abundances of Firmicutes phylum, Clostridiaceae_1 family, Methylobacterium and Candidatus Arthromitus genera but decreased the abundance of Nitrosomonas genus and Rhizobium cellulosilyticum and Rubrobacter xylanophilus species as compared with the only S. typhimurium-challenged birds. In conclusion, Arg supplementation can alleviate intestinal mucosal impairment by ameliorating inflammatory response and modulating gut microbiota in broiler chickens challenged with S. typhimurium.
Topics: Animal Feed; Animals; Arginine; Bacterial Physiological Phenomena; Chickens; Diet; Dietary Supplements; Gastrointestinal Microbiome; Inflammation; Intestines; Male; Poultry Diseases; Random Allocation; Salmonella Infections, Animal; Salmonella typhimurium; Stress, Physiological
PubMed: 32241466
DOI: 10.1016/j.psj.2019.10.049 -
Journal of Hazardous Materials Apr 2020Currently, radioactive waste is disposed primarily by burial in a deep geological repository. Microorganisms thriving in such contaminated environment show tolerance to...
Currently, radioactive waste is disposed primarily by burial in a deep geological repository. Microorganisms thriving in such contaminated environment show tolerance to radionuclides. In the present study the bacterial flora, from soil sample collected from an area around atomic power station exposed to radionuclides and heavy metals, was cultivated and assessed for thorium (Th) tolerance. Of all the isolates, strain AM7 identified as O. intermedium was selected since it could thrive at high levels of Th (1000 mg L). AM7 was characterized physico-chemically and its culture medium was optimized using central composite design of response surface methodology for assessing its growth properties in presence of Th. The strain also showed exceptional exopolysaccharide (EPS) production and its yield was further analyzed using one factor study to investigate the influence of each medium component. On supplementing the EPS medium with Th, no significant decrease in yield was observed. FTIR spectroscopy revealed the functional groups of EPS involved in EPS-Th binding. To the best of our knowledge, this is the first report showing exceptional Th-tolerance by any bacteria. Such study will help other researchers to strategize an environment-friendly way of radwaste disposal.
Topics: Biopolymers; Microbial Consortia; Ochrobactrum; Polysaccharides, Bacterial; RNA, Ribosomal, 16S; Radiation Tolerance; Soil Pollutants, Radioactive; Thorium Compounds
PubMed: 31954311
DOI: 10.1016/j.jhazmat.2020.122047 -
Chemosphere Apr 2020Pot-culture experiments were conducted to investigate the potential of microorganism-saponin assisted phytoremediation of cadmium (Cd) and benzo(a)pyrene (B[a]P)...
Pot-culture experiments were conducted to investigate the potential of microorganism-saponin assisted phytoremediation of cadmium (Cd) and benzo(a)pyrene (B[a]P) co-contaminated soil using Cd-hyperaccumulator Sedum alfredii. Results showed that B[a]P-degrading bacterium (Ochrobactrum intermedium B[a]P-16) inoculation significantly increased root (by 22.1-24.1%) and shoot (by 20.5-23.4%) biomass of S. alfredii, whereas the application of saponin had no effect on the growth of S. alfredii. The saponin solution at 2 g L extracted more Cd and B[a]P than water, saponin enhanced Cd and B[a]P bioavailability in soil and thus promoted their uptake and accumulation in S. alfredii. The activity of B[a]P-16, dehydrogenase and polyphenol oxidase in co-contaminated soil was promoted by growing S. alfredii, and the application of B[a]P-16 and saponins caused a significant (P < 0.05) increase in both enzyme activities. The maximum B[a]P removal rate (82.0%) and Cd phytoextraction rate (19.5%) were obtained by co-application of S. alfredii with B[a]P-16 and saponin. The B[a]P-16 and plant promoted biodegradation were the predominant contributors towards removal of B[a]P from soil. A significant (P < 0.05) synergistic effect of B[a]P-16 and saponin on B[a]P and Cd removal efficiency was observed in this study. It is suggested that planting S. alfredii with application of B[a]P-16 and saponin would be an effective method for phytoremediation of soil co-contaminated with Cd and PAHs.
Topics: Benzo(a)pyrene; Biodegradation, Environmental; Biomass; Cadmium; Ochrobactrum; Polycyclic Aromatic Hydrocarbons; Saponins; Sedum; Soil; Soil Microbiology; Soil Pollutants
PubMed: 31864950
DOI: 10.1016/j.chemosphere.2019.125547 -
Canadian Journal of Microbiology Feb 2020Growth and productivity of rice are negatively affected by soil salinity. However, some salt-tolerant rhizosphere-inhabiting bacteria can improve salt resistance of...
Growth and productivity of rice are negatively affected by soil salinity. However, some salt-tolerant rhizosphere-inhabiting bacteria can improve salt resistance of plants, thereby augmenting plant growth and production. Here, we isolated a total of 53 plant-growth-promoting rhizobacteria (PGPR) from saline and non-saline areas in Bangladesh where electrical conductivity was measured as >7.45 and <1.80 dS/m, respectively. Bacteria isolated from saline areas were able to grow in a salt concentration of up to 2.60 mol/L, contrary to the isolates collected from non-saline areas that did not survive beyond 854 mmol/L. Among the salt-tolerant isolates, , , and , identified by comparing respective sequences of 16S rRNA using the NCBI GenBank, exhibited a higher amount of atmospheric nitrogen fixation, phosphate solubilization, and indoleacetic acid production at 200 mmol/L salt stress. Salt-tolerant isolates exhibited greater resistance to heavy metals and antibiotics, which could be due to the production of an exopolysaccharide layer outside the cell surface. L. fertilized with MS3 and grown under 200 mmol/L salt stress was found to be favoured by enhanced expression of a set of at least four salt-responsive plant genes: , , , and . Fertilization of rice with osmoprotectant-producing PGPR, therefore, could be a climate-change-preparedness strategy for coastal agriculture.
Topics: Achromobacter denitrificans; Bacillus; Bangladesh; Indoleacetic Acids; Nitrogen Fixation; Ochrobactrum; Oryza; Phosphates; RNA, Ribosomal, 16S; Rhizosphere; Salinity; Salt Stress; Salt Tolerance; Soil; Soil Microbiology
PubMed: 31714812
DOI: 10.1139/cjm-2019-0323 -
Environmental Science and Pollution... Jul 2019Farmland soil sprayed with organophosphorus pesticides (OPs) annually was investigated for the identification and characterization of OP-degrading microorganisms. Six...
Farmland soil sprayed with organophosphorus pesticides (OPs) annually was investigated for the identification and characterization of OP-degrading microorganisms. Six bacterial strains were identified, including Brevundimonas faecalis MA-B12 and Alcaligenes faecalis subsp. parafaecalis MA-B13 for methamidophos degradation, Citrobacter freundii TF-B21 and Ochrobactrum intermedium TF-B23 for trichlorfon degradation, Ochrobactrum intermedium DV-B31 for dichlorvos degradation, and Bacillus cereus for dimethoate degradation. The optimal biodegradation conditions for OPs were obtained at pH 7.0 and incubation temperature ranging from 28 to 37 °C. In an 8-day batch test, biodegradation of the four OPs all followed first-order kinetics, with biodegradation rates ranging from 58.08 to 96.42%. Functional genes responsible for OPs degradation were obtained, including ophB, ampA, opdE, opd, opdA, and mpd. As these strains were indigenous strains isolated from farmland soils, they can be potentially used as bacterial consortium for the bioremediation of mixed OP-contaminated soils. A time-course genotoxicity assessment of the degradation products was done by a bacterial whole-cell bioreporter, revealing that biodegradation of trichlorfon, dichlorvos, and dimethoate resulted a decreased genotoxicity within 5 days, which, however, significantly increased on day 8. The result demonstrated that more toxic products may be produced during the biodegradation processes of OPs, and more attention should be put not only on the pesticides themselves, but also on the toxic effects of their degradation products. To the best of our knowledge, this is for the first time that the genotoxicity of OP degradation products was evaluated by the bioreporter assay, broadening our understanding on the genotoxic risks of OPs during biodegradation process. Graphical Abstract.
Topics: Bacillus cereus; Biodegradation, Environmental; DNA Damage; Dichlorvos; Dimethoate; Kinetics; Organophosphorus Compounds; Pesticides; Soil
PubMed: 31129897
DOI: 10.1007/s11356-019-05135-9 -
Access Microbiology 2019Wastewater has become a potential habitat for multi-drug-resistant bacteria. The present study aims to screen for the presence of carbapenem-resistant bacteria in sewage...
Wastewater has become a potential habitat for multi-drug-resistant bacteria. The present study aims to screen for the presence of carbapenem-resistant bacteria in sewage water samples collected from hospital and non-hospital sources. From a total of 19 sewage water samples collected, 100 carbapenem-resistant non-lactose-fermenting Gram-negative bacteria (CR-NF-GNB) were isolated using MacConkey agar cultured with 8 mg l of meropenem. On screening for beta-lactamase resistance genes ( , , , and ), one isolate, , was found to carry the plasmid-borne gene. To the best of our knowledge, we provide the first report of the rare and emerging opportunistic pathogen encoding the OXA-181 gene in its plasmid.
PubMed: 32974517
DOI: 10.1099/acmi.0.000024 -
Journal of Hazardous Materials Jul 2019Plant-bacterial mutualism has tremendous potential for remediation of herbicide contaminated soils. Generally, bacterial inoculation helps plants to grow well in the...
Plant-bacterial mutualism has tremendous potential for remediation of herbicide contaminated soils. Generally, bacterial inoculation helps plants to grow well in the contaminated environment. Here, we investigated the impact of bispyribac sodium (BS) degrading bacterial consortium (BDAM) on BS remediation, plant growth promotion and BS accumulation in plant parts. Wheat (Triticum aestivum) was planted in BS spiked soil and inoculated with BDAM. Inoculation showed a beneficial effect on plant biomass production and degradation of BS in the rhizosphere and the rhizosheath. After 40 and 60 days of inoculation, the degradation of BS was more than 96% and approximately 100% respectively in the planted and inoculated soil spiked with 2 and 5 mg kg BS. However, in planted and un-inoculated soil, the degradation of BS was 72% after 60 days of sowing. Furthermore, inoculated bacterial strains colonized both in rhizo- and endosphere of the inoculated plants. In comparison with the un-inoculated soil, significantly less accumulation of BS was found in the roots and shoots of the plants growing in inoculated soil. We report the efficiency of plant-bacterial partnership for enhanced biodegradation of BS and to eliminate the BS residual toxicity to non-target plants.
Topics: Achromobacter; Achromobacter denitrificans; Bacteria; Benzoates; Biodegradation, Environmental; Biomass; Herbicides; Microbial Consortia; Ochrobactrum; Plant Roots; Pyrimidines; Rhizosphere; Soil; Soil Microbiology; Soil Pollutants; Triticum
PubMed: 30978631
DOI: 10.1016/j.jhazmat.2019.03.130