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Environmental Research Oct 2022Most bacteria in the natural environment have a biofilm mode of life, which is intrinsically tolerant to antibiotics. While until now, the knowledge of biofilm formation...
Most bacteria in the natural environment have a biofilm mode of life, which is intrinsically tolerant to antibiotics. While until now, the knowledge of biofilm formation by Acinetobacter johnsonii is not well understood. In this study, the characteristics and the effect of a sub-inhibitory concentration of antibiotic on A. johnsonii biofilm and planktonic cells were determined. We discovered a positive relationship between biofilm formation and tetracycline resistance, and biofilms rapidly evolve resistance to tetracycline they are treated with. Persister cells commonly exist in both planktonic and biofilm cells, with a higher frequency in the latter. Further transcriptomic analysis speculates that the overexpression of multidrug resistance genes and stress genes were mainly answered to sub lethal concentration of tetracycline in planktonic cells, and the lower metabolic levels after biofilm formation result in high resistance level of biofilm cells to tetracycline. Altogether, these data suggest that A. johnsonii can adjust its phenotype when grown as biofilm and change its metabolism under antibiotic stress, and provide implications for subsequent biofilm control.
Topics: Acinetobacter; Anti-Bacterial Agents; Biofilms; Microbial Sensitivity Tests; Plankton; Tetracycline; Transcriptome
PubMed: 35718162
DOI: 10.1016/j.envres.2022.113714 -
Biodegradation Feb 20224-Hydroxybenzoic acid (4-HBA) is a common organic compound that is prevalent in the environment, and the persistence of 4-HBA residues results in exertion of...
4-Hydroxybenzoic acid (4-HBA) is a common organic compound that is prevalent in the environment, and the persistence of 4-HBA residues results in exertion of pollution-related detrimental effects. Bioremediation is an effective method for the removal of 4-HBA from the environment. In this study, two bacterial strains FZ-5 and FZ-8 capable of utilizing 4-HBA as the sole carbon and energy source under anaerobic conditions were isolated from marine sediment samples. Phylogenetic analysis identified the two strains FZ-5 and FZ-8 as Acinetobacter johnsonii and Klebsiella oxytoca, respectively. The strains FZ-5 and FZ-8 degraded 2000 mg·L 4-HBA in 72 h with degradation rates of 71.04% and 80.10%, respectively. The optimum culture conditions for degradation by the strains and crude enzymes were also investigated. The strains FZ-5 and FZ-8 also exhibited the ability to degrade other lignin-derived compounds, such as protocatechuic acid, cinnamic acid, and vanillic acid. Immobilization of the two strains showed that they could be used for the bioremediation of 4-HBA in an aqueous environment. Soils inoculated with the strains FZ-5 and FZ-8 showed higher degradation of 4-HBA than the uninoculated soil, and the strains could survive efficiently in anaerobic soil. This is the first report of 4-HBA-degrading bacteria, belonging to the two genera, which showed degradation ability under anaerobic conditions. This study expound the strains could efficiently degrade 4-HBA in anaerobic soil and will help in the development of 4-HBA anaerobic bioremediation systems.
Topics: Acinetobacter; Anaerobiosis; Bacteria; Biodegradation, Environmental; Klebsiella oxytoca; Parabens; Phylogeny; Soil; Soil Microbiology
PubMed: 34609628
DOI: 10.1007/s10532-021-09963-w -
Gene Jan 2022Genome plasticity is a key determinant that Acinetobacter johnsonii could widely distribute in natural and clinical environments. However, little attention has been paid...
Genome plasticity is a key determinant that Acinetobacter johnsonii could widely distribute in natural and clinical environments. However, little attention has been paid to figure out the changes in the genome during A. johnsonii's evolution. Here, a comparative genomic analysis of A. johnsonii isolated from clinical and environmental sources was conducted. In this study, we found A. johnsonii has an open pan-genome and has great adaptability to different environments. Based on the results of the phylogenetic tree, ANI value and the distribution of accessory genes, we found that strains from the same habitat had a high degree of similarity. Though genes associated with the fundamental process were mostly conserved in evolution, clinical-derived isolates accumulate more genes associated with translational modification, β-lactamase and defense mechanisms, whereas environmental-derived isolates enriched more genes related to substances degradation. In addition, clinical-derived strains harbored some "strong" virulence islands and resistance islands. This study highlights the evolutionary relationship of A. johnsonii isolates from clinical and environmental sources.
Topics: Acinetobacter; Adaptation, Biological; Biological Evolution; China; Databases, Genetic; Evolution, Molecular; Genome, Bacterial; Genomics; Phylogeny; Virulence
PubMed: 34600047
DOI: 10.1016/j.gene.2021.145985 -
Journal of Applied Microbiology Sep 2022The role of a Acinetobacter johnsonii strain, isolated from a soil sample, in the biotransformation of bile acids (BAs) was already described but the enzymes responsible...
AIMS
The role of a Acinetobacter johnsonii strain, isolated from a soil sample, in the biotransformation of bile acids (BAs) was already described but the enzymes responsible for these transformations were only partially purified and molecularly characterized.
METHODS AND RESULTS
This study describes the use of hybrid de novo assemblies, that combine long-read Oxford Nanopore and short-read Illumina sequencing strategies, to reconstruct the entire genome of A. johnsonii ICE_NC strain and to identify the coding region for a 12α-hydroxysteroid dehydrogenase (12α-HSDH), involved in BAs metabolism. The de novo assembly of the A. johnsonii ICE_NC genome was generated using Canu and Unicycler, both strategies yielded a circular chromosome of about 3.6 Mb and one 117 kb long plasmid. Gene annotation was performed on the final assemblies and the gene for 12α-HSDH was detected on the plasmid.
CONCLUSIONS
Our findings illustrate the added value of long read sequencing in addressing the challenges of whole genome characterization and plasmid reconstruction in bacteria. These approaches also allowed the identification of the A. johnsonii ICE_NC gene for the 12α-HSDH enzyme, whose activity was confirmed at the biochemical level.
SIGNIFICANCE AND IMPACT OR THE STUDY
At present, this is the first report on the characterization of a 12α-HSDH gene in an A. johnsonii strain able to biotransform cholic acid into ursodeoxycholic acid, a promising therapeutic agent for several diseases.
Topics: Acinetobacter; Bile Acids and Salts; Genome, Bacterial; High-Throughput Nucleotide Sequencing; Hydroxysteroid Dehydrogenases
PubMed: 35686660
DOI: 10.1111/jam.15657 -
Environmental Research May 2021Acinetobacter johnsonii is a potentially opportunistic pathogen widely distributed in nosocomial and natural environments, but little attention has been paid to this...
Acinetobacter johnsonii is a potentially opportunistic pathogen widely distributed in nosocomial and natural environments, but little attention has been paid to this bacillus. Here A. johnsonii strains from Ba River with different pollution levels were isolated. In this study, we found that the increasing anthropogenic contaminants accounted for the emergence of multidrug-resistant (MDR) A. johnsonii strains. Correlation analysis results showed that the resistance phenotype of strains could be generated by co-selection of heavy metals or non-corresponding antibiotics. The whole genome sequence analysis showed that the relative heavy pollution of water selects strains containing more survival-relevant genes. We found that only some genes like bla were responsible for its corresponding resistance profile. Additionally, the tolerance profiles toward heavy metals also attribute to the expression of efflux pumps rather than corresponding resistance genes. In summary, our finding revealed that the resistance profiles of A. johnsonii could be generated by cross or co-selection of anthropogenic contaminants and mediated by efflux pumps instead of corresponding resistance determinants. Our study also has deep-sight into the adaptive preference of bacteria in natural environments, and contributes to surveillance studies and MDR- A. johnsonii monitoring worldwide.
Topics: Acinetobacter; Anti-Bacterial Agents; Drug Resistance, Multiple, Bacterial; Microbial Sensitivity Tests; Phenotype; Rivers
PubMed: 33639142
DOI: 10.1016/j.envres.2021.110913 -
MSphere Jul 2020has been severely understudied and its population structure and the presence of antibiotic resistance genes (ARGs) are very much uncertain. Our phylogeographical...
has been severely understudied and its population structure and the presence of antibiotic resistance genes (ARGs) are very much uncertain. Our phylogeographical analysis shows that intercontinental transmission has occurred frequently and that different lineages are circulating within single countries; notably, clinical and nonclinical strains are not well differentiated from one another. Importantly, in this species recombination is a significant source of single nucleotide polymorphisms. Furthermore, our results show this species could be an important reservoir of ARGs since it has a significant amount of ARGs, and many of them show signals of horizontal gene transfer. Thus, this study clearly points out the clinical importance of and the urgent need to better appreciate its genomic diversity.
Topics: Acinetobacter; Anti-Bacterial Agents; Drug Resistance, Multiple, Bacterial; Gene Transfer, Horizontal; Genes, Bacterial; Genetic Variation; Genome, Bacterial; Phylogeny; Phylogeography
PubMed: 32611704
DOI: 10.1128/mSphere.00581-20 -
Frontiers in Cellular and Infection... 2023The emergence of carbapenemase-producing spp. has been widely reported and become a global threat. However, carbapenem-resistant strains are relatively rare and...
The emergence of carbapenemase-producing spp. has been widely reported and become a global threat. However, carbapenem-resistant strains are relatively rare and without comprehensive genetic structure analysis, especially for isolates collected from human specimen. Here, one AYTCM strain, co-producing NDM-1, OXA-58, and PER-1 enzymes, was isolated from sputum in China in 2018. Antimicrobial susceptibility testing showed that it was resistant to meropenem, imipenem, ceftazidime, ciprofloxacin, and cefoperazone/sulbactam. Whole-genome sequencing and bioinformatic analysis revealed that it possessed 11 plasmids. and genes were located in the pAYTCM-1 plasmid. Especially, a complex class 1 integron consisted of a 5' conserved segment (5' CS) and 3' CS, which was found to carry sul1, arr-3, qnrVC6 cassettes. Moreover, the gene was located in 41,087 conjugative plasmids and was quite stable even after 70 passages under antibiotics-free conditions. In addition, six prophage regions were identified. Tracking of closely related plasmids in the public database showed that pAYTCM-1 was similar to pXBB1-9, pOXA23_010062, pOXA58_010030, and pAcsw19-2 plasmids, which were collected from the strains of sewage in China. Concerning the pAYTCM-3 plasmids, results showed that strains were collected from different sources and their hosts were isolated from various countries, such as China, USA, Japan, Brazil, and Mexico, suggesting that a wide spread occurred all over the world. In conclusion, early surveillance is warranted to avoid the extensive spread of this high-risk clone in the healthcare setting.
Topics: Humans; Carbapenems; Genes, Regulator; Transcription Factors; Acinetobacter
PubMed: 37692162
DOI: 10.3389/fcimb.2023.1227063 -
Ecotoxicology and Environmental Safety Nov 2018Polycyclic aromatic hydrocarbons (PAHs) usually co-exist in environment with interactional effects. Currently, Acinetobacter johnsonii was employed to degrade...
Polycyclic aromatic hydrocarbons (PAHs) usually co-exist in environment with interactional effects. Currently, Acinetobacter johnsonii was employed to degrade 400 mg L of pyrene (PYR) and kinetic modeling indicated substrate inhibition over 76 mg L by introducing an inhibition constant parameter. In PAHs co-biodegradation, naphthalene (NAP) dominated biodegradation processes through the preferential utilization as growth substrate. The peak biodegradation of PYR increased to 415 mg L with 65 mg L of NAP. Furthermore, phenanthrene (PHE), PYR and anthracene (ANT) were degraded in turn and ended in reverse order. When the concentrations reached their respective limiting concentration of 22%, ANT could not be degraded and PHE and PYR biodegradations also respectively terminated at 66 and 45 h later with a removal rate of 40% and 26% due to very low specific activities of salicylate hydroxylase and catechol 2,3-dioxygenase. However, by introducing 125-133 mg L of NAP, the bacterial potential was effectively enhanced to 29% after cell underwent a re-stimulation stage with the exhaustion of NAP. NAP prominently contributed to cell growth to stimulate secretion of key enzymes, but the advantage would gradually get lost with the decline of its titer. To research the interplay of PAHs is conducive to targeted decontamination.
Topics: Acinetobacter; Biodegradation, Environmental; Polycyclic Aromatic Hydrocarbons
PubMed: 30075449
DOI: 10.1016/j.ecoenv.2018.07.065 -
Biotechnology For Biofuels 2020Acetylacetone is a commercially bulk chemical with diverse applications. However, the traditional manufacturing methods suffer from many drawbacks such as multiple...
BACKGROUND
Acetylacetone is a commercially bulk chemical with diverse applications. However, the traditional manufacturing methods suffer from many drawbacks such as multiple steps, harsh conditions, low yield, and environmental problems, which hamper further applications of petrochemical-based acetylacetone. Compared to conventional chemical methods, biosynthetic methods possess advantages such as being eco-friendly, and having mild conditions, high selectivity and low potential costs. It is urgent to develop biosynthetic route for acetylacetone to avoid the present problems.
RESULTS
The biosynthetic pathway of acetylacetone was constructed by reversing its biodegradation route, and the acetylacetone was successfully produced by engineered () by overexpression of acetylacetone-cleaving enzyme (Dke1) from . Several promising amino acid residues were selected for enzyme improvement based on sequence alignment and structure analysis, and the acetylacetone production was improved by site-directed mutagenesis of Dke1. The double-mutant (K15Q/A60D) strain presented the highest acetylacetone-producing capacity which is 3.6-fold higher than that of the wild-type protein. Finally, the strain accumulated 556.3 ± 15.2 mg/L acetylacetone in fed-batch fermentation under anaerobic conditions.
CONCLUSIONS
This study presents the first intuitive biosynthetic pathway for acetylacetone inspired by its biodegradation, and shows the potential for large-scale production.
PubMed: 32454892
DOI: 10.1186/s13068-020-01725-9 -
Frontiers in Microbiology 2021This study investigates the physicochemical changes and water migration of (A), (S), and cocultured and (AS) inoculated into bigeye tuna during cold storage. The...
This study investigates the physicochemical changes and water migration of (A), (S), and cocultured and (AS) inoculated into bigeye tuna during cold storage. The physicochemical indexes [fluorescence ratio (FR), total volatile base nitrogen (TVB-N), thiobarbituric acid (TBA), trimethylamine (TMA), peroxide value (POV), and pH] of bigeye tuna increased cold storage. A significant decrease in trapped water was found in the AS samples, and direct monitoring of the water dynamics was provided by low-field nuclear magnetic resonance. Samples inoculated with and also induced the degradation of myofibrillar proteins and weakness of some Z-lines and M-lines. Higher values of physicochemical indexes and water dynamics were shown in the coculture of and than in the other groups. Therefore, this paper reveals that the coculture of and resulted in a bigeye tuna that was more easily spoiled when compared to the single culture. This study provides insight into the spoilage potential of and during cold storage, which further assists in the application of appropriate technologies to keep the freshness of aquatic foods.
PubMed: 34777276
DOI: 10.3389/fmicb.2021.727333