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Huan Jing Ke Xue= Huanjing Kexue Aug 2019Due to the problems of traditional biological nitrogen and phosphorus removal, including long process duration and high infrastructural and operational costs, the...
Due to the problems of traditional biological nitrogen and phosphorus removal, including long process duration and high infrastructural and operational costs, the simultaneous nitrogen and phosphorus removal capabilities, influencing factors and kinetic characteristics were systematically studied using the heterotrophic nitrifier NP1 which possesses efficient simultaneous nitrogen and phosphorus removal ability. The results showed that strain NP1 exhibited efficient heterotrophic nitrification ability with a maximum ammonia removal rate of 99.12%. Furthermore, only small amounts of nitrification intermediates were accumulated during the reaction process. Strain NP1 also adapted well to higher ammonia nitrogen loading. In addition, strain NP1 had efficient aerobic denitrification characteristics, and could utilize nitrite and nitrate for growth and metabolism, achieving a maximum removal rate of 91.40% and 95.10%, respectively. The heterotrophic nitrification process of strain NP1 was accompanied by simultaneous phosphorus accumulation, and the appropriate ratio of nitrogen to phosphorus was beneficial for the simultaneous removal of nitrogen and phosphorus. When the ratio of nitrogen to phosphorus was 5:1, the maximum ammonia nitrogen and phosphate removal rates reached 99.21% and 88.35%, respectively. The bacterial growth process of stain NP1 matched the Logistic model (>0.99), and the nitrogen and phosphate degradation conformed to the Compertz model (>0.99). The maximum conversion rates of nitrogen and phosphate () obtained by model fitting were in the order ammonia>nitrate>nitrite, and lag time (0) was in the order nitrate>nitrite>ammonia. According to the analysis of the degradation kinetics of the matrix and the removal rate of nitrogen and phosphorus, the optimal conditions were found to be sodium succinate, C/N=10, =30℃, and =160 r·min.
Topics: Acinetobacter; Aerobiosis; Denitrification; Heterotrophic Processes; Kinetics; Nitrification; Nitrites; Nitrogen; Phosphorus; Water Purification
PubMed: 31854780
DOI: 10.13227/j.hjkx.201901208 -
Microbiology Spectrum Dec 2022New Delhi metallo-β-lactamase (NDM)-producing clinical strains in Acinetobacter spp. have been recently reported in many countries and have received considerable...
New Delhi metallo-β-lactamase (NDM)-producing clinical strains in Acinetobacter spp. have been recently reported in many countries and have received considerable attention. The vast majority of cases occur on conjugative plasmids, which play a vital role in disseminating . To characterize the conjugative plasmids bearing genes in Acinetobacter spp., we analyzed the variants of , conjugative transfer regions, genetic contexts of , and the phylogenetic pattern of the 62 predicted -positive plasmids, which were selected from 1,191 plasmids of Acinetobacter species from GenBank. We identified 30 conjugative plasmids from the 62 -harboring plasmids in Acinetobacter species, with the sites similar to plasmid pNDM-YR7 in our study, genes coding for relaxases of the MOB family, genes encoding type IV coupling proteins (T4CPs) of the TrwB/TraD subfamily, and VirB-like type IV secretion system (T4SS) gene clusters. The genome sizes of all 30 pNDM-YR7-like plasmids ranged from 39.36 kb to 49.65 kb, with a median size of 44.56 kb. The most common species of Acinetobacter containing the -positive conjugative plasmids was A. baumannii, followed by Acinetobacter lwoffii and Acinetobacter indicus. Notably, pNDM-YR7 is the first report on a -positive conjugative plasmid in Acinetobacter junii. Moreover, all 30 -positive conjugative plasmids in Acinetobacter species were found to contain genetic contexts with the structure IS--IS--. Our findings provide important insights into the phylogeny and evolution of -positive plasmids of Acinetobacter species and further address their role in acquiring and spreading genes in Acinetobacter species. Conjugative plasmids harboring the gene play a vital role in disseminating carbapenem resistance. In this study, we first report a conjugative plasmid, pNDM-YR7, in Acinetobacter junii. Based on the genomic characteristics of the -positive pNDM-YR7, we performed typing and comparative analysis of -positive plasmids using the 1,191 plasmids of Acinetobacter species available in the NCBI RefSeq database. We analyzed the characteristics of -positive plasmids, including the variants of , genetic features associated with , conjugative transfer regions, and the phylogenetic pattern of the -positive plasmids. All 30 -positive conjugative plasmids were found to contain an IS--IS-- region. This study provides novel insights into the phylogeny and evolution of -harboring conjugative plasmids and contributes to the repertoire of knowledge surrounding -positive plasmids in the genus Acinetobacter.
Topics: Phylogeny; Acinetobacter; Plasmids; beta-Lactamases; Anti-Bacterial Agents; Microbial Sensitivity Tests
PubMed: 36301090
DOI: 10.1128/spectrum.02102-22 -
Research in Microbiology Jun 2023Water sources (surface water, drinking water, rivers, and ponds) are significant reservoirs for transmitting antibiotic-resistant bacteria. In addition, these waters are...
Water sources (surface water, drinking water, rivers, and ponds) are significant reservoirs for transmitting antibiotic-resistant bacteria. In addition, these waters are an important public health problem because they are suitable environments for transferring antibiotic resistance genes between bacterial species. Our study aimed to assess the prevalence of Extended-spectrum beta-lactamase (ESBL) producing isolates in water samples, the susceptibility of the isolates to the specified antibiotics, the determination of biofilm ability, antibiotic resistance genes, and the molecular typing of the isolates. For this purpose, Polymerase chain reaction (PCR) and Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) analyses were used. Out of 70 isolates, 15 (21%) were ESBL producing, and sent for the MALDI-TOF analysis, where Escherichia coli, Acinetobacter calcoaceticus, Enterobacter bugandensis, Acinetobacter pittii, Pseudomonas aeruginosa, Acinetobacter junii, Pseudomonas oleovorans, and Enterobacter ludwigigii were identified. Moreover, colistin resistance genes (mcr 1/2/6, mcr 4, mcr 5, mcr 3/7, and mcr 8), ESBL-encoding genes (bla, bla, and bla) and carbapenemase genes (bla, bla, and bla) using molecular analysis (PCR) were confirmed. The colistin resistance gene was detected at 80% (12/15) in the isolates obtained. The distribution of these isolates according to resistance genes was found as mcr 1/2/6 4 (20%), mcr 3/7 3 (13%), and mcr 5 (40%). Additionally, the isolates harbored bla(6.6%) and bla (6.6%) genes. However, bla, bla, bla, and bla genes were not detected in any isolates. According to the Congo red agar method, seven (46.6%) isolates showed negative biofilm ability, and eight (53.3%) showed moderate biofilm ability. However, the microplate method detected weak biofilm in 53.3% of the isolates. In conclusion, this study provides evidence for the existence of multidrug-resistant bacteria that co-exist with mcr and ESBL genes in water sources. These bacteria can migrate to other environments and pose increasing threats to public health.
Topics: Colistin; Anti-Bacterial Agents; beta-Lactamases; Escherichia coli; Bacteria; Drug Resistance, Multiple, Bacterial; Water; Escherichia coli Proteins; Microbial Sensitivity Tests
PubMed: 37004897
DOI: 10.1016/j.resmic.2023.104056 -
Heliyon Feb 2023The utilization and improper use of crude oil can have irreparable damage on the environment and human populations. This study sought to isolate hydrocarbon utilizing...
The utilization and improper use of crude oil can have irreparable damage on the environment and human populations. This study sought to isolate hydrocarbon utilizing bacteria from 1% v/v pristine seawater and 1% v/v crude oil using enrichment culture techniques. Whole genome sequencing of DNA using the Oxford Nanopore sequencing technique with Fastq WIMP as the workflow at 3% abundance was undertaken. The results showed that the most abundant isolates identified using this technique at specific sampling sites were, (51.9%) (15.8%) (21.6%) (23.4%) (24.7%) (23.0%) (40.0%) and (14.2%). Cumulatively, the most abundant isolates in the 8 sampling sites were (17.91%), (11.68%) (7.68%) (7.67%) (3.40%) (3.10%). Spearman's rank correlation analysis to examine the strength of relationship between the physicochemical parameters and type of bacteria isolated, revealed that salinity (0.8046) and pH (0.7252) were the highest. Isolated bacteria from pristine seawater, especially have shown their capacity for bioremediating oil spill pollution in oceanic environments in Ghana.
PubMed: 36785818
DOI: 10.1016/j.heliyon.2023.e13075 -
Heliyon Feb 2024This study was aimed at using microcosm experiments to assess crude oil degradation efficiency of and isolated along Ghana's coast. Uncontaminated seawater from...
This study was aimed at using microcosm experiments to assess crude oil degradation efficiency of and isolated along Ghana's coast. Uncontaminated seawater from selected locations along the coast was used to isolate bacterial species by employing enrichment culture procedures with crude oil as the only carbon source. The isolates were identified by means of the extended direct colony transfer method of the Matrix Assisted Laser Desorption Ionization Time of Flight Mass Spectroscopy (MALDI-TOF MS), as , and . Remediation tests showed that yielded degradation efficiencies of 27.59 %, 41.38 % and 57.47 %. Whereas efficiencies of 21.14 %, 32.18 % and 43.68 % were recorded by representing 15, 30 and 45 days respectively. Consortia of , and also yielded 32.18 %, 48.28 % and 62.07 % for the selected days respectively. Phylogenetic characterization using ClustalW and BLAST of sequences generated from the Oxford Nanopore Sequencing technique, showed that the Ghanaian isolates clustered with and species respectively. An analysis of the sequenced data for the 1394-bp portion of the 16S rRNA gene of the isolates revealed >99 % sequence identity with the isolates present on the GenBank database. The isolates of closest identity were and with accession numbers, NR_133958.1 and KJ147060.1 respectively. and isolated from Ghana's coast under pristine seawater conditions have therefore demonstrated their capacity to be used for the remediation of crude oil spills.
PubMed: 38318038
DOI: 10.1016/j.heliyon.2024.e24994 -
Bioresource Technology Apr 2024This work aims at intensifying the simultaneous removal of nitrogen and phosphorus of an integrated aerobic granular sludge (AGS) - membrane bioreactor (MBR) by...
This work aims at intensifying the simultaneous removal of nitrogen and phosphorus of an integrated aerobic granular sludge (AGS) - membrane bioreactor (MBR) by Acinetobacter junii. After acclimation and enrichment in a sequencing batch reactor (SBR), Acinetobacter junii, a kind of denitrifying phosphate accumulating organism (DPAO), was successfully screened in the used SBR. Then it was verified to be capable of effectively enhancing the performance in the simultaneous removal of nitrogen and phosphorus of AGS-MBR. In the system, DPAO (Acinetobacter junii) mainly occurred in AGS, and the highest ratio even reached 22.8%, but its competitive advantages highly depend on the size of AGS. The presented results can cultivate AGS and enrich DPAO simultaneously to improve the removal of nitrogen and phosphorus of an AGS-MBR, which provide an environmentally friendly approach to upgrade traditional wastewater treatment processes.
Topics: Sewage; Phosphorus; Nitrogen; Phosphates; Bioreactors; Waste Disposal, Fluid; Acinetobacter
PubMed: 38395234
DOI: 10.1016/j.biortech.2024.130474 -
Microbiology Resource Announcements Aug 2021Acinetobacter junii INC8271 was isolated from a cancer patient with polymicrobial bacteremia after biliary stent placement. The complete genome sequence consisted of a...
Acinetobacter junii INC8271 was isolated from a cancer patient with polymicrobial bacteremia after biliary stent placement. The complete genome sequence consisted of a chromosome of 3,530,883 bp (GC content, 38.56%) with 3,377 genes, including those encoding 74 tRNAs and 18 rRNAs, and two intact prophage sequences. No antibiotic resistance genes were detected.
PubMed: 34410161
DOI: 10.1128/MRA.00604-21 -
Microbiology Spectrum Apr 2024Tigecycline is an antibiotic of last resort for infections with carbapenem-resistant . Plasmids harboring variants of the tetracycline destructase gene promote rising...
UNLABELLED
Tigecycline is an antibiotic of last resort for infections with carbapenem-resistant . Plasmids harboring variants of the tetracycline destructase gene promote rising tigecycline resistance rates. We report the earliest observation of ) in a clinical strain predating tigecycline's commercialization, suggesting selective pressures other than tigecycline contributed to its emergence.
IMPORTANCE
We present the earliest observation of a ()-positive bacterial strain, predating by many years the earliest reports of this gene so far. This finding is significant as tigecycline is an antibiotic of last resort for carbapenem-resistant (CRAB), which the World Health Organization ranks as one of its top three critical priority pathogens, and () variants have become the most prevalent genes responsible for enabling CRAB to become tigecycline resistant. Moreover, the ()-positive strain we report is the first and only to be found that predates the commercialization of tigecycline, an antibiotic that was thought to have contributed to the emergence of this resistance gene. Understanding the factors contributing to the origin and spread of novel antibiotic resistance genes is crucial to addressing the major global public health issue, which is antimicrobial resistance.
Topics: Tigecycline; Microbial Sensitivity Tests; Anti-Bacterial Agents; Tetracycline; Plasmids; Carbapenems
PubMed: 38412527
DOI: 10.1128/spectrum.03327-23 -
Surgical Infections Mar 2022
Topics: Acinetobacter; Bile Duct Neoplasms; Cholangitis; Humans; Klatskin Tumor; Stents
PubMed: 34668785
DOI: 10.1089/sur.2021.264 -
Journal of Global Antimicrobial... Jun 2023Colistin-resistant Gram-negative pathogens have become a serious worldwide medical problem. This study was designed to reveal the effects of an intrinsic...
OBJECTIVES
Colistin-resistant Gram-negative pathogens have become a serious worldwide medical problem. This study was designed to reveal the effects of an intrinsic phosphoethanolamine transferase from Acinetobacter modestus on Enterobacterales.
METHODS
A strain of colistin-resistant A. modestus was isolated from a sample of nasal secretions taken in 2019 from a hospitalised pet cat in Japan. The whole genome was sequenced by next generation sequencing, and transformants of Escherichia coli, Klebsiella pneumoniae, and Enterobacter cloacae harbouring the phosphoethanolamine transferase-encoding gene from A. modestus were constructed. Lipid A modification in E. coli transformants was analysed using electrospray ionization mass spectrometry.
RESULTS
Sequencing of the entire genome revealed that the isolate harboured a phosphoethanolamine transferase-encoding gene, eptA_AM, on its chromosome. Transformants of E. coli, K. pneumoniae, and E. cloacae harbouring both the promoter and eptA_AM gene from A. modestus had 32-fold, 8-fold, and 4-fold higher minimum inhibitory concentrations (MICs) for colistin, respectively, than transformants harbouring a control vector. The genetic environment surrounding eptA_AM in A. modestus was similar to that surrounding eptA_AM in Acinetobacter junii and Acinetobacter venetianus. Electrospray ionization mass spectrometry analysis revealed that EptA_AM modified lipid A in Enterobacterales.
CONCLUSION
This is the first report to describe the isolation of an A. modestus strain in Japan and show that its intrinsic phosphoethanolamine transferase, EptA_AM, contributes to colistin resistance in Enterobacterales and A. modestus.
Topics: Animals; Cats; Colistin; Escherichia coli; Lipid A; Ethanolaminephosphotransferase; Bacterial Proteins; Drug Resistance, Bacterial; Anti-Bacterial Agents; Klebsiella pneumoniae
PubMed: 36906175
DOI: 10.1016/j.jgar.2023.02.023