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Microorganisms Oct 2022Diazotroph mutants designed using metabolic engineering to excrete surplus ammonium were used to enhance nitrogen fixation and plant growth, as the levels of nitrogen...
Diazotroph mutants designed using metabolic engineering to excrete surplus ammonium were used to enhance nitrogen fixation and plant growth, as the levels of nitrogen fixation attained with diazotrophs are insufficient for the plant's needs. In this study, wild-type (A1501) and engineered ammonium-excreting (1568/pVA3) strains of nitrogen-fixing strains were tested in vitro based on plant growth-promoting traits, such as phosphate solubilization ability, indole acetic acid (IAA) production and nitrogenase activities, as well as ammonium excretion as affected by mannitol-mediated osmotic stress. The maize plant growth-promoting effect of the A1501 and 1568/pVA3 strains was evaluated in pots and in the field, and the N-dilution technique was employed to assess the proportion of plant nitrogen derived from nitrogen fixation. The results demonstrate that the 1568/pVA3 strain displayed higher IAA production and nitrogenase activity than A1501 and released significant quantities of ammonium. After 50 days, in all of the conditions assayed, maize inoculated with 1568/pVA3 accumulated more plant biomass (3.3% on average) and fixed N (39.4% on average) than plants inoculated with A1501. In the field experiment, the grain yield of maize was enhanced by 5.6% or 5.9% due to the inoculation of seeds with 1568/pVA3 in the absence or presence of exogenous N fertilizer, respectively. Therefore, the engineered strain tested in the greenhouse and field was shown to perform better than the wild-type strain with respect to maize growth parameters and biologically fixed nitrogen.
PubMed: 36296262
DOI: 10.3390/microorganisms10101986 -
Applied and Environmental Microbiology Oct 2021The reaction sequence for aerobic degradation of bile salts by environmental bacteria resembles degradation of other steroid compounds. Recent findings show that...
Comparative Analysis of Bile-Salt Degradation in sp. Strain Chol11 and Pseudomonas stutzeri Strain Chol1 Reveals Functional Diversity of Proteobacterial Steroid Degradation Enzymes and Suggests a Novel Pathway for Side Chain Degradation.
The reaction sequence for aerobic degradation of bile salts by environmental bacteria resembles degradation of other steroid compounds. Recent findings show that bacteria belonging to the use a pathway variant for bile-salt degradation. This study addresses this so-called Δ-variant by comparative analysis of unknown degradation steps in sp. strain Chol11 with known reactions found in Pseudomonas stutzeri Chol1. Investigations of strain Chol11 revealed an essential function of the acyl-CoA dehydrogenase (ACAD) Scd4AB for growth with bile salts. Growth of the deletion mutant was restored with a metabolite containing a double bond within the side chain which was produced by the Δ-ACAD Scd1AB from P. stutzeri Chol1. Expression of in the deletion mutant fully restored growth with bile salts, while expression of only enabled constricted growth in P. stutzeri Chol1 or deletion mutants. Strain Chol11 Δ accumulated hydroxylated steroid metabolites which were degraded and activated with coenzyme A by the wild type. Activities of five Rieske type monooxygenases of strain Chol11 were screened by heterologous expression and compared to the B-ring cleaving KshAB from P. stutzeri Chol1. Three of the Chol11 enzymes catalyzed B-ring cleavage of only Δ-steroids, while KshAB was more versatile. Expression of a fourth KshA homolog, Nov2c228, led to production of metabolites with hydroxylations at an unknown position. These results indicate functional diversity of proteobacterial enzymes for bile-salt degradation and suggest a novel side chain degradation pathway involving an essential ACAD reaction and a steroid hydroxylation step. This study highlights the biochemical diversity of bacterial degradation of steroid compounds in different aspects. First, it further elucidates an unexplored variant in the degradation of bile-salt side chains by sphingomonads, a group of environmental bacteria that is well-known for their broad metabolic capabilities. Moreover, it adds a so far unknown hydroxylation of steroids to the reactions Rieske monooxygenases can catalyze with steroids. Additionally, it analyzes a proteobacterial ketosteroid-9α-hydroxylase and shows that this enzyme is able to catalyze side reactions with nonnative substrates.
Topics: Acyl-CoA Dehydrogenase; Bacterial Proteins; Bile Acids and Salts; Mixed Function Oxygenases; Pseudomonas stutzeri; Sphingomonadaceae; Steroids
PubMed: 34469190
DOI: 10.1128/AEM.01453-21 -
Foods (Basel, Switzerland) Sep 2023The fermented liquid sector is developing all over the world due to its contribution to health. Our study has contributed to the debate about whether industrially...
The fermented liquid sector is developing all over the world due to its contribution to health. Our study has contributed to the debate about whether industrially manufactured fermented liquids live up to their claims by analyzing pathogens and beneficial bacteria using a 16S rRNA sequencing technique called metagenomic analysis. , , , , , and were the most abundant bacterial genera observed as potential probiotics. , , and , which have plant-growth-promoting traits, were also detected. The fact that we encounter biocontroller bacteria that promote plant growth demonstrates that these organisms are widely used in foods and emphasizes the necessity of evaluating them in terms of public health. Their potential applications in agriculture may pose a danger to food hygiene and human health in the long term, so our data suggest that this should be evaluated.
PubMed: 37835192
DOI: 10.3390/foods12193538 -
Journal of Infection Prevention Nov 2020Protective lead garments (PLG) worn in the operating room are a potential source for bacterial colonisation and thus may increase the risk of intraoperative infection....
BACKGROUND
Protective lead garments (PLG) worn in the operating room are a potential source for bacterial colonisation and thus may increase the risk of intraoperative infection. The clinical significance of such bacterial contamination has yet been established. Although disinfection protocols have been employed, their effectiveness is also unknown.
OBJECTIVE
We sought to describe and compare the bacterial profile of PLGs with a focus on common pathogens involved in surgical site infections (SSI) and prosthetic joint infections (PJI).
METHODS
We studied body aprons and neck-thyroid protective shields. We sampled 20 body aprons and 21 neck PLGs, swabbing the inside and outside of the PLGs. Swabs were cultured on different media and the results were assessed and compared.
RESULTS
Of PLGs, 87.8% were contaminated. The neck-thyroid shield PLGs was generally more contaminated than body apron PLGs and exhibited significantly higher loads of ( = 0.048). Other pathogen cultured were spp., (), species ( spp.), () and (). No other common pathogens associated with SSI or PJI were detected.
CONCLUSIONS
PLGs are heavily contaminated despite regular cleaning protocols. Neck PLGs are highly contaminated with potentially infectious agents. As neck PLGs are often directly exposed above the surgical sterile gown and the surgical field, measures should be undertaken to reduce their exposure and bacterial load, perhaps by suggesting users consider avoiding the use of intraoperative fluoroscopy when possible or alternatively supporting the use of body exhaust suits when PLGs are needed.
PubMed: 33408761
DOI: 10.1177/1757177420947466 -
Frontiers in Microbiology 2023() has been found principally in oil-polluted environments. The capability of to thrive from the degradation of pollutant compounds makes it a species of interest for...
() has been found principally in oil-polluted environments. The capability of to thrive from the degradation of pollutant compounds makes it a species of interest for potential bioremediation applications. However, little has been reported about the diversity of . In this study, genome sequences of strains from different origins were analyzed, revealing that it is a diverse species with an open pan-genome that will continue revealing new genes and functionalities as the genomes of more strains are sequenced. The nucleotide signatures and intra- and inter-species variation of the 16S rRNA genes of were reevaluated. A strategy of screening 16S rRNA gene sequences in public databases enabled the detection of 158 additional strains, of which only 23% were described as . The species was detected from a wide range of environments, although mostly from aquatic and polluted environments, predominantly related to petroleum oil. Genomic and phenotypic analyses confirmed that possesses varied inherent capabilities for aromatic compounds degradation. This study increases the knowledge of the biology and diversity of and will serve as a basis for future work with the species.
PubMed: 37275147
DOI: 10.3389/fmicb.2023.1159176 -
Microbial Biotechnology Jan 2020In agricultural production, sustainability is currently one of the most significant concerns. The genetic modification of plant growth-promoting rhizobacteria may...
In agricultural production, sustainability is currently one of the most significant concerns. The genetic modification of plant growth-promoting rhizobacteria may provide a novel way to use natural bacteria as microbial inoculants. In this study, the root-colonizing strain Pseudomonas protegens Pf-5 was genetically modified to act as a biocontrol agent and biofertilizer with biological nitrogen fixation activity. Genetic inactivation of retS enhanced the production of 2,4-diacetylphloroglucinol, which contributed for the enhanced antifungal activity. Then, the entire nitrogenase island with native promoter from Pseudomonas stutzeri DSM4166 was introduced into a retS mutant strain for expression. Root colonization patterns assessed via confocal laser scanning microscopy confirmed that GFP-tagged bacterial were mainly located on root surfaces and at the junctions between epidermal root cells. Moreover, under pathogen and N-limited double treatment conditions, the fresh weights of seedlings inoculated with the recombinant retS mutant-nif strain were increased compared with those of the control. In conclusion, this study has innovatively developed an eco-friendly alternative to the agrochemicals that will benefit global plant production significantly.
Topics: Bacterial Proteins; Biological Control Agents; Nitrogen Fixation; Nitrogenase; Plant Roots; Protein Engineering; Pseudomonas; Pseudomonas stutzeri
PubMed: 30461205
DOI: 10.1111/1751-7915.13335 -
Journal of Global Antimicrobial... Dec 2020The aim of this study was to screen for the presence of β-lactamase-producing Gram-negative bacteria (GNB) from Algerian currency collected from food vendors in Batna...
OBJECTIVES
The aim of this study was to screen for the presence of β-lactamase-producing Gram-negative bacteria (GNB) from Algerian currency collected from food vendors in Batna city, Algeria.
METHODS
During two periods (May 2018 and March-April 2019), a total of 408 coins and currency notes of different denominations of Algerian Dinar were randomly recovered from several food vendors. Samples were subjected to selective isolation of extended-spectrum cephalosporin- and carbapenem-resistant GNB. Bacterial species identification was performed using matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF/MS). Antibiotic susceptibility testing was performed by the disk diffusion method. Carbapenemase and extended-spectrum β-lactamase (ESBL) genes were searched for by real-time PCR, standard PCR and sequencing. The clonal relationship of carbapenemase-producing isolates was investigated by multilocus sequence typing (MLST). The transferability of the detected carbapenemase-encoding gene was verified by conjugation experiments.
RESULTS
Twelve cefotaxime- and/or carbapenem-resistant strains were isolated in this study and were identified as Enterobacter cloacae, Raoultella ornithinolytica, Citrobacter freundii, Escherichia coli, Pseudomonas aeruginosa, Pseudomonas libanensis and Pseudomonas stutzeri. The bla gene was detected in only one E. cloacae strain belonging to sequence type 108 (ST108), whilst the two R. ornithinolytica isolates harboured bla and one E. coli strain carried bla. The detected bla gene was transferable by conjugation.
CONCLUSIONS
We report for the first time the detection of an OXA-48-producing E. cloacae isolate from money. This calls for consciousness development on the potential risks associated with poor handling of currency.
Topics: Algeria; Anti-Bacterial Agents; Enterobacter cloacae; Enterobacteriaceae; Escherichia coli; Multilocus Sequence Typing; Numismatics; Pseudomonas; beta-Lactamases
PubMed: 32966913
DOI: 10.1016/j.jgar.2020.09.003 -
Biotechnology Reports (Amsterdam,... Dec 2020We report the complete genome sequencing of novel strain MP4687 isolated from cattle rumen. Various strains of have been reported from different environmental samples...
We report the complete genome sequencing of novel strain MP4687 isolated from cattle rumen. Various strains of have been reported from different environmental samples including oil-contaminated sites, crop roots, air, and human clinical samples, but not from rumen samples, which is being reported here for the first time. The genome of P. stutzeri MP4687 has a single replicon, 4.75 Mb chromosome and a G + C content of 63.45%. The genome encodes for 4,790 protein coding genes including 164 CAZymes and 345 carbohydrate processing genes. The isolate MP4687 harbors LCB hydrolyzing potential through endoglucanase (4.5 U/mL), xylanase (3.1 U/mL), β-glucosidase (3.3 U/mL) and β-xylosidase (1.9 U/mL) activities. The pangenome analysis further revealed that MP4687 has a very high number of unique genes (>2100) compared to other genomes, which might have an important role in rumen functioning.
PubMed: 32983925
DOI: 10.1016/j.btre.2020.e00530 -
3 Biotech May 2020Textile industry is one of the anthropogenic activities that consume a large amount of water and pollute water bodies. It uses a massive amount of dyes, which is one of...
Textile industry is one of the anthropogenic activities that consume a large amount of water and pollute water bodies. It uses a massive amount of dyes, which is one of the main constituents of polluting textile effluent. In the present research, biodegradation of Acid Blue 113 dye, a commonly used textile di-azo dye, has been studied exploiting , strain AK6. The dye (300 ppm) was decolorized up to 86.2% within 96 h. The metabolites of Acid Blue 113 obtained after biodegradation were identified by various analytical techniques viz. HPLC (high-performance liquid chromatography) and GC-MS (gas chromatography-mass spectrometry). Genome analysis of isolate AK6 using IMG/M (Integrated Microbial Genomes and Microbiomes) system supported the role of azoreductase and laccase for the decolorization and degradation of azo dye. The ability of AK6 to tolerate high amount of dye makes it a potential candidate for bioremediation and pre-processing to remove dyes from textile effluents.
PubMed: 32351872
DOI: 10.1007/s13205-020-02205-5 -
ELife Jul 2022Root exudates are thought to play an important role in plant-microbial interactions. In return for nutrition, soil bacteria can increase the bioavailability of soil...
Root exudates are thought to play an important role in plant-microbial interactions. In return for nutrition, soil bacteria can increase the bioavailability of soil nutrients. However, root exudates typically decrease in situations such as drought, calling into question the efficacy of solvation and bacteria-dependent mineral uptake in such stress. Here, we tested the hypothesis of exudate-driven microbial priming on saplings grown in forest soil in custom-made rhizotron boxes. A 1-month imposed drought and concomitant inoculations with a mix of and , bacteria species isolated from the forest soil, were applied using factorial design. Direct bacteria counts and visualization by confocal microscopy showed that both bacteria associated with roots. Interestingly, root exudation rates increased 2.3-fold with bacteria under drought, as well as irrigation. Forty-four metabolites in exudates were significantly different in concentration between irrigated and drought trees, including phenolic acid compounds and quinate. When adding these metabolites as carbon and nitrogen sources to bacterial cultures of both bacterial species, eight of nine metabolites stimulated bacterial growth. Importantly, soil phosphorous bioavailability was maintained only in inoculated trees, mitigating drought-induced decrease in leaf phosphorus and iron. Our observations of increased root exudation rate when drought and inoculation regimes were combined support the idea of root recruitment of beneficial bacteria, especially under water stress.
Topics: Bacteria; Droughts; Plant Roots; Rhizosphere; Soil; Soil Microbiology; Trees
PubMed: 35858113
DOI: 10.7554/eLife.79679