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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 -
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 -
Foods (Basel, Switzerland) Mar 2022This study aimed to investigate the antibacterial properties and mechanisms of a high-voltage static electric field (HVEF) in which were assessed from the perspective...
This study aimed to investigate the antibacterial properties and mechanisms of a high-voltage static electric field (HVEF) in which were assessed from the perspective of biochemical properties and stress-related genes. The time/voltage-kill assays and growth curves showed that an HVEF decreased the number of bacteria and OD600 values. In addition, HVEF treatment caused the leakage of cell contents (nucleic acids and proteins), increased the electrical conductivity and amounts of reactive oxygen substances (ROS) (16.88 fold), and decreased the activity of Na+ K+-ATPase in . Moreover, the changes in the expression levels of genes involved in oxidative stress and DNA damage in the treated cells suggested that HVEF treatment could induce oxidative stress and DNA sub-damage. This study will provide useful information for the development and application of an HVEF in food safety.
PubMed: 35407042
DOI: 10.3390/foods11070955 -
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 -
Research in Microbiology Jun 2017A double-stranded DNA phage named AJO1, infecting Acinetobacter johnsonii, which plays an important role in wastewater treatment, was isolated from activated sludge in a...
A double-stranded DNA phage named AJO1, infecting Acinetobacter johnsonii, which plays an important role in wastewater treatment, was isolated from activated sludge in a full-scale municipal wastewater treatment plant. Based on morphological taxonomy, AJO1, with an icosahedral head 55 ± 2 nm in diameter and a non-contractile tail 8 ± 2 nm in length, was classified as a member of the Podoviridae family. Bacterial infection characteristics were as follows: no polyvalent infectivity, optimal multiplicity of infection of 10; eclipse and burst size of 30 min and 51.2 PFU-infected cells, respectively. It showed considerable infectivity under a neutral pH condition (pH 6.0-9.0) and relatively high temperature (55 °C). Whole-genome sequencing of AJO1 revealed a linearly permuted DNA (41 437 bp) carrying 54 putative open reading frames and 4 repeats. This is the first report of isolation of an A. johnsonii phage, whose bacteriophage distribution and population dynamics are not well known. The results of this study could contribute to subsequent research on the interaction between bacteriophages and their hosts during wastewater treatment. In addition, AJO1 may become a candidate for potential therapy against A. johnsonii infection in clinical applications, since this species is an opportunistic pathogen.
Topics: Acinetobacter; Bacteriophages; DNA, Viral; Genome, Viral; Host-Pathogen Interactions; Hydrogen-Ion Concentration; Open Reading Frames; Podoviridae; Sequence Analysis, DNA; Sewage; Viral Proteins; Wastewater
PubMed: 28213104
DOI: 10.1016/j.resmic.2017.01.006 -
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 -
Nanomaterials (Basel, Switzerland) Nov 2022The interaction between nanoplastics and bacteria remains still largely unclear. In this study, we determined the effect of nanopolystyrene particle (NP) on a bacterial...
The interaction between nanoplastics and bacteria remains still largely unclear. In this study, we determined the effect of nanopolystyrene particle (NP) on a bacterial pathogen of Acinetobacter johnsonii AC15. Scanning electron microscopy (SEM) analysis indicated the aggregation of NPs from 10 μg/L to 100 μg/L on surface of A. johnsonii AC15, suggesting that A. johnsonii AC15 acted as the vector for NPs. Exposure to 100−1000 μg/L NPs increased the growth and colony-forming unit (CFU) of A. johnsonii AC15. In addition, exposure to 100−1000 μg/L NPs enhanced the amount of formed biofilm of A. johnsonii AC15. Alterations in expressions of 3 survival-related (zigA, basD, and zur), 5 biofilm formation-related (ompA, bap, adeG, csuC, and csuD), and 3 serum resistance-related virulence genes (lpxC, lpxL, and pbpG) were observed after exposure to 1000 μg/L NPs. Moreover, both CFU and survival rate of A. johnsonii AC15 in normal human serum (NHS) were significantly increased by 1−1000 μg/L NPs, suggesting the enhancement in serum resistance of Acinetobacter pathogen by NPs. In the NHS, expressions of 3 survival-related (zigA, basD, and zur), 9 biofilm formation-related (ompA, bap, adeF, adeG, csuA/B, csuC, csuD, csuE, and hlyD), and 3 serum resistance-related virulence genes (lpxC, lpxL, and pbpG) were affected by 1000 μg/L NPs. Expressions of 1 survival-related (zigA), 5 biofilm formation-related (bap, adeG, csuC, csuD, and csuE), and 3 serum resistance-related virulence genes (lpxC, lpxL, and pbpG) were also altered by 10 μg/L NPs after the addition of NHS. Therefore, exposure to NPs in the range of μg/L has the potential to enhance bacterial virulence by increasing their growth, biofilm formation, and serum resistance.
PubMed: 36500844
DOI: 10.3390/nano12234222 -
Frontiers in Microbiology 2019A novel lytic phage AJO2, specifically infecting , was isolated from bulking activated sludge. The one-step growth experiment showed that the latent period and burst...
A novel lytic phage AJO2, specifically infecting , was isolated from bulking activated sludge. The one-step growth experiment showed that the latent period and burst size of AJO2 were estimated to be 30 min and 78.1 phages per infected cell, respectively. The viability test indicated that neutral conditions (pH 6-8) were table for AJO2 survival, while it was sensitive to high temperature (≥60°C) and ultraviolet treatment (254 nm). Genomic sequencing revealed that the AJO2 had a linearly permuted, double-stranded (ds) DNA consisting of 38,124 bp, with the G+C content of 41 mol%. A total of 58 putative open reading frames (ORFs), 11 pairs of repeats and 11 promoters were identified. The AJO2 genome had a modular gene structure which shared some similarities to those of phages. However, genomic comparative analysis revealed many differences among them, and novel genes were identified in the AJO2 genome. These results contribute to subsequent researches on the interaction between bacteriophages and hosts in wastewater treatment, especially during the bulking period. Additionally, the newly isolated phage could be a good candidate as a therapeutic agent to control nosocomial infections caused by
PubMed: 30873130
DOI: 10.3389/fmicb.2019.00266 -
Frontiers in Microbiology 2023The co-existence of hydroxylamine (NHOH) and nitrite (NO -N) can aggravate the difficulty of wastewater treatment. The roles of hydroxylamine (NHOH) and nitrite (NO -N)...
The co-existence of hydroxylamine (NHOH) and nitrite (NO -N) can aggravate the difficulty of wastewater treatment. The roles of hydroxylamine (NHOH) and nitrite (NO -N) in accelerating the elimination of multiple nitrogen sources by a novel isolated strain of EN-J1 were investigated in this study. The results demonstrated that strain EN-J1 could eliminate 100.00% of NHOH (22.73 mg/L) and 90.09% of NO -N (55.32 mg/L), with maximum consumption rates of 1.22 and 6.75 mg/L/h, respectively. Prominently, the toxic substances NHOH and NO -N could both facilitate nitrogen removal rates. Compared with the control treatment, the elimination rates of nitrate (NO -N) and NO -N were enhanced by 3.44 and 2.36 mg/L/h after supplementation with 10.00 mg/L NHOH, and those of ammonium (NH -N) and NO -N were improved by 0.65 and 1.00 mg/L/h after the addition of 50.00 mg/L NO -N. Furthermore, the nitrogen balance results indicated that over 55.00% of the initial total nitrogen was transformed into gaseous nitrogen by heterotrophic nitrification and aerobic denitrification (HN-AD). Ammonia monooxygenase (AMO), hydroxylamine oxidoreductase (HAO), nitrate reductase (NR), and nitrite reductase (NIR), which are essential for HN-AD, were detected at levels of 0.54, 0.15, 0.14, and 0.01 U/mg protein, respectively. All findings confirmed that strain EN-J1 could efficiently execute HN-AD, detoxify NHOH and NO -N, and ultimately promote nitrogen removal rates.
PubMed: 37138626
DOI: 10.3389/fmicb.2023.1130512 -
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