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Biotechnology Reports (Amsterdam,... Dec 2021The mechanisms of tolerance to heavy metals used by some microorganisms identified by bioprospection processes are useful for the development and implementation of...
The mechanisms of tolerance to heavy metals used by some microorganisms identified by bioprospection processes are useful for the development and implementation of bioremediation strategies for contaminated environments with high toxic load caused by heavy metals. A total of seven native microbial isolates were obtained from wastewater bodies from an industrial zone in the municipality of Girardota, Antioquia, Colombia. Subsequently, they were selected to evaluate their lead tolerance capacity at different concentrations. In addition, some parameters were determined, such as the capacity to produce exopolysaccharides and their biosorption to understand potential mechanisms associated to lead tolerance. According to the biocehemical test (Vitek) and the molecular analysis of sequences of 16S rDNA, bacterial were identified as , and . We determined that the seven isolates had the capacity to tolerate concentrations higher than 50 mg/ml of lead, and that the concentration and exposure time (40 h) to this metal significantly affect the spp. isolates. Statistically significant differences were detected ( < 0.05) in the production of the exopolysaccharide (EPS) among the isolates. (P16) was the strain with the maximum absorbance exopolysaccharide measured. We evidenced that (P14) and (P20) have 80% capacity to biosorber lead using live mass (minimum range from 80.9% to 87%). It is suggested that the tolerance to lead exhibited by the environmental isolates of spp. can be attributed to the production of exopolysaccharides and biosorption, which are protection factors for its survival in contaminated places. Finally, it was determined that the adsorption measured from dead biomass was significant ( < 0.05) from 40 h of exposure to metal (Average 182.2 ± 7). We generated new knowledge about the potential use of the spp. genus to bioremediate affluent contaminated with heavy metals.
PubMed: 34765463
DOI: 10.1016/j.btre.2021.e00685 -
Frontiers in Microbiology 2021Quorum quenching (QQ) is a novel, promising strategy that opens up a new perspective for controlling quorum-sensing (QS)-mediated bacterial pathogens. QQ is performed by...
Quorum quenching (QQ) is a novel, promising strategy that opens up a new perspective for controlling quorum-sensing (QS)-mediated bacterial pathogens. QQ is performed by interfering with population-sensing systems, such as by the inhibition of signal synthesis, catalysis of degrading enzymes, and modification of signals. In many Gram-negative pathogenic bacteria, a class of chemically conserved signaling molecules named -acyl homoserine lactones (AHLs) have been widely studied. AHLs are involved in the modulation of virulence factors in various bacterial pathogens including . is the causal agent of plant-rot disease of bananas, rice, maize, potatoes, etc., causing enormous economic losses of crops. In this study, a highly efficient AHL-degrading bacterial strain W-7 was isolated from activated-sludge samples and identified as . Strain W-7 revealed a superior ability to degrade -(3-oxododecanoyl)-l-homoserine lactone (OdDHL) and completely degraded 0.2 mmol/L of OdDHL within 48 h. Gas chromatography-mass spectrometry (GC-MS) identified -cyclohexyl-propanamide as the main intermediate metabolite during AHL biodegradation. A metabolic pathway for AHL in strain W-7 was proposed based on the chemical structure of AHL and intermediate products. In addition to the degradation of OdDHL, this strain was also found to be capable of degrading a wide range of AHLs including -(3-oxohexanoyl)-l-homoserine lactone (OHHL), -(3-oxooctanoyl)-l-homoserine lactone (OOHL), and -hexanoyl-l-homoserine lactone (HHL). Moreover, the application of strain W-7 as a biocontrol agent could substantially attenuate the soft rot caused by EC1 to suppress tissue maceration in various host plants. Similarly, the application of crude enzymes of strain W-7 significantly reduced the disease incidence and severity in host plants. These original findings unveil the biochemical aspects of a highly efficient AHL-degrading bacterial isolate and provide useful agents that exhibit great potential for the control of infectious diseases caused by AHL-dependent bacterial pathogens.
PubMed: 34413838
DOI: 10.3389/fmicb.2021.694161 -
BMJ Case Reports May 2021A man in his 50s with neutropenic fever and multifocal lung opacities was diagnosed with a viral pneumonia. A small number of bacteria grown from bronchoalveolar lavage...
A man in his 50s with neutropenic fever and multifocal lung opacities was diagnosed with a viral pneumonia. A small number of bacteria grown from bronchoalveolar lavage fluid collected during a repeat bronchoscopy were initially identified as by VITEK-2 and mass spectrometry platforms. Whole-genome sequencing, however, subsequently demonstrated that the bacteria were , representing the first known case of cultured from human lungs.
Topics: Bronchoalveolar Lavage Fluid; Humans; Lung; Male; Pneumonia; Pseudomonas; Pseudomonas Infections; Pseudomonas aeruginosa
PubMed: 34031078
DOI: 10.1136/bcr-2020-241327 -
Genes Aug 2020The sewage sludge isolate HBP-1 was the first bacterium known to completely degrade the fungicide 2-hydroxybiphenyl. PacBio and Illumina whole-genome sequencing...
The sewage sludge isolate HBP-1 was the first bacterium known to completely degrade the fungicide 2-hydroxybiphenyl. PacBio and Illumina whole-genome sequencing revealed three circular DNA replicons: a chromosome and two plasmids. Plasmids were shown to code for putative adaptive functions such as heavy metal resistance, but with unclarified ability for self-transfer. About one-tenth of strain HBP-1's chromosomal genes are likely of recent horizontal influx, being part of genomic islands, prophages and integrative and conjugative elements (ICEs). carries two large ICEs with different functional specialization, but with homologous core structures to the well-known ICE of B13. The variable regions of ICE1 (96 kb) code for, among others, heavy metal resistances and formaldehyde detoxification, whereas those of ICE2 (171 kb) encodes complete -cleavage pathways for catabolism of 2-hydroxybiphenyl and salicylate, a protocatechuate pathway and peripheral enzymes for 4-hydroxybenzoate, ferulate, vanillin and vanillate transformation. Both ICEs transferred at frequencies of 10-10 per HBP-1 donor into , where they integrated site specifically into -gene targets, as expected. Our study highlights the underlying determinants and mechanisms driving dissemination of adaptive properties allowing bacterial strains to cope with polluted environments.
Topics: Computational Biology; Conjugation, Genetic; DNA Transposable Elements; DNA, Bacterial; Disinfectants; Fatty Acids; Gene Order; Gene Transfer, Horizontal; Genome, Bacterial; Genomic Islands; Genomics; High-Throughput Nucleotide Sequencing; Molecular Sequence Annotation; Plasmids; Prophages; Pseudomonas
PubMed: 32806781
DOI: 10.3390/genes11080930 -
Applied and Environmental Microbiology Aug 2020The enzymatic production of 2,5-furandicarboxylic acid (FDCA) from 5-hydroxymethylfurfural (HMF) has gained interest in recent years, as FDCA is a renewable precursor of...
The enzymatic production of 2,5-furandicarboxylic acid (FDCA) from 5-hydroxymethylfurfural (HMF) has gained interest in recent years, as FDCA is a renewable precursor of poly(ethylene-2,5-furandicarboxylate) (PEF). 5-Hydroxymethylfurfural oxidases (HMFOs) form a flavoenzyme family with genes annotated in a dozen bacterial species but only one enzyme purified and characterized to date (after heterologous expression of a sp. HMFO gene). This oxidase acts on both furfuryl alcohols and aldehydes and, therefore, is able to catalyze the conversion of HMF into FDCA through 2,5-diformylfuran (DFF) and 2,5-formylfurancarboxylic acid (FFCA), with only the need of oxygen as a cosubstrate. To enlarge the repertoire of HMFO enzymes available, genetic databases were screened for putative HMFO genes, followed by heterologous expression in After unsuccessful trials with other bacterial HMFO genes, HMFOs from two species were produced as active soluble enzymes, purified, and characterized. The sp. enzyme was also produced and purified in parallel for comparison. Enzyme stability against temperature, pH, and hydrogen peroxide, three key aspects for application, were evaluated (together with optimal conditions for activity), revealing differences between the three HMFOs. Also, the kinetic parameters for HMF, DFF, and FFCA oxidation were determined, the new HMFOs having higher efficiencies for the oxidation of FFCA, which constitutes the bottleneck in the enzymatic route for FDCA production. These results were used to set up the best conditions for FDCA production by each enzyme, attaining a compromise between optimal activity and half-life under different conditions of operation. HMFO is the only enzyme described to date that can catalyze by itself the three consecutive oxidation steps to produce FDCA from HMF. Unfortunately, only one HMFO enzyme is currently available for biotechnological application. This availability is enlarged here by the identification, heterologous production, purification, and characterization of two new HMFOs, one from and one from an unidentified species. Compared to the previously known HMFO, the new enzyme from exhibits better performance for FDCA production in wider pH and temperature ranges, with higher tolerance for the hydrogen peroxide formed, longer half-life during oxidation, and higher yield and total turnover numbers in long-term conversions under optimized conditions. All these features are relevant properties for the industrial production of FDCA. In summary, gene screening and heterologous expression can facilitate the selection and improvement of HMFO enzymes as biocatalysts for the enzymatic synthesis of renewable building blocks in the production of bioplastics.
Topics: Bacterial Proteins; Dicarboxylic Acids; Escherichia coli; Furaldehyde; Furans; Methylophilaceae; Microorganisms, Genetically-Modified; Oxidoreductases; Pseudomonas
PubMed: 32503910
DOI: 10.1128/AEM.00842-20 -
3 Biotech Apr 20205-Enolpyruvylshikimate 3-phosphate synthase (EPSPS) is the primary target for the broad-spectrum herbicide, glyphosate. Improvement of gene for high level of glyphosate...
5-Enolpyruvylshikimate 3-phosphate synthase (EPSPS) is the primary target for the broad-spectrum herbicide, glyphosate. Improvement of gene for high level of glyphosate tolerance is important to generate glyphosate-tolerant crops. In this study, we report the isolation and characterization of genes of glyphosate-tolerant strains FY43 and FY47. Both strains FY43 and FY47, which showed glyphosate tolerance up to 8.768% (518.4 mM, 32 × higher than field application), were isolated from soil samples collected from oil palm plantation with a long history of glyphosate application. The glyphosate tolerance property of genes of strains FY43 and FY47 was functionally characterized by expressing the genes in strain BL21(DE3). Error-prone PCR was performed to mutagenize native gene of strains FY43 and FY47. Ten mutagenized EPSPS with amino acid changes (R21C, N265S, A329T, P71L, T258A, L184F, G292C, G292S, L35F and A242V) were generated through error-prone PCR. Both native and mutated genes of strains FY43 and FY47 were introduced into strain BL21(DE3) and transformants were selected on basal salt medium supplemented with 8.768% (518.4 mM) glyphosate. Mutants with mutations (R21C, N265S, A329T, P71L, T258A, L35F, A242V, L184F and G292C) showed sensitivity to 8.768% glyphosate, whereas glyphosate tolerance for mutant with G292S mutation was not affected by the mutation.
PubMed: 32257739
DOI: 10.1007/s13205-020-02176-7 -
Microbiology (Reading, England) Jan 2020Azelaic acid is a dicarboxylic acid that has recently been shown to play a role in plant-bacteria signalling and also occurs naturally in several cereals. Several...
Azelaic acid is a dicarboxylic acid that has recently been shown to play a role in plant-bacteria signalling and also occurs naturally in several cereals. Several bacteria have been reported to be able to utilize azelaic acid as a unique source of carbon and energy, including . In this study, we utilize as a model organism to study bacterial degradation of and response to azelaic acid. We report genetic evidence of azelaic acid degradation and the identification of a transcriptional regulator that responds to azelaic acid in DSM 9128. Three mutants possessing transposons in genes of an acyl-CoA ligase, an acyl-CoA dehydrogenase and an isocitrate lyase display a deficient ability in growing in azelaic acid. Studies on transcriptional regulation of these genes resulted in the identification of an IclR family repressor that we designated as AzeR, which specifically responds to azelaic acid. A bioinformatics survey reveals that AzeR is confined to a few proteobacterial genera that are likely to be able to degrade and utilize azelaic acid as the sole source of carbon and energy.
Topics: Bacteria; Bacterial Proteins; Dicarboxylic Acids; Gene Expression Regulation, Bacterial; Molecular Structure; Mutation; Phylogeny; Promoter Regions, Genetic; Pseudomonas; Repressor Proteins; Transcription Factors
PubMed: 31621557
DOI: 10.1099/mic.0.000865