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Shaha CM, Dar MA, Pandit RS. Mining the diversity and functional profile of bacterial symbionts from the larvae of Chironomus circumdatus (bloodworms). Folia Microbiol (Praha) 2022; 67:861-872. [PMID: 35729301 DOI: 10.1007/s12223-022-00984-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 06/10/2022] [Indexed: 11/24/2022]
Abstract
Chironomids are the most abundant aquatic insects in freshwater habitats that can survive in extreme conditions. In this study, as the microbiome provides extended genotype to the host to perform various functions, we explored the microbiota of the Chironomus circumdatus larvae to find out the putative role played by the symbiotic bacteria for the host. The metabarcoding analyses of the larvae revealed that the insect harbors 1771 phylotypes. Out of the various microbial communities found, the majority corresponded to the phyla Proteobacteria (52.59%) and Actinobacteria (20.56%), respectively. The midges also harbored Klebsiella (2.57%), Enterobacter (1.32%), Bacillus (2.29%), and Acinetobacter (2.13%) genera that are involved in detoxification of xenobiotics present in the water. The presence of radiation-resistant genera like Deinococcus, including bacterial species like radiodurans, a highly radiation-resistant bacterium, indicates its potential to support the host's ability to sustain in adverse environments. The functional profiling of the bacteria showed the relative abundance of many enzyme groups, such as transferases (40.62%), oxidoreductases (23.49%), and hydrolases (3.77%). The results indicate that the larvae harbor a considerable variety of bacteria that help the host adapt and survive in the polluted waters. The present study provides thorough insights into the microbiome of the C. circumdatus larvae that can be exploited for the bioremediation of certain pollutants through biomimetic strategies. It also gives us a wake-up call to take a good look at the guts of these disease-carrying insects' inabilities to spread deadly human diseases.
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Affiliation(s)
- Chaitali M Shaha
- Department of Zoology, Savitribai Phule Pune University, Ganeshkhind, Pune, 411007, India
| | - Mudasir A Dar
- School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, 212013, China
| | - Radhakrishna S Pandit
- Department of Zoology, Savitribai Phule Pune University, Ganeshkhind, Pune, 411007, India.
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Al-Mohaimeed AM, Abbasi AM, Ali MA, Dhas DSD. Reduction of multiple antibiotics from the waste water using coated glutathione S-transferase producing biocatalyst. ENVIRONMENTAL RESEARCH 2022; 206:112262. [PMID: 34695426 DOI: 10.1016/j.envres.2021.112262] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 10/10/2021] [Accepted: 10/18/2021] [Indexed: 06/13/2023]
Abstract
Oxytetracycline is widely used in veterinary and human medicine. It has been detected in wastewater from pharmaceuticals, hospitals and domestic wastewater. In recent years, much more attention has been directed towards glutathione transferases (GSTs) because of their bio-transforming ability of antibiotics. In this study, 19 Lactobacillus strains were initially screened for the production of GSTs and five strains were selected for biotransformation of oxytetracycline. Among the strains, L. fermentum LA6 improved oxytetracyline degradation than other strains. It was subjected to optimize GST production and optimum growth was achieved after 24 h incubation at 32 ± 2 °C and 200 mg/L initial oxytetracycline concentration. The biocatalyst was immobilized and antibiotic degradation efficiency was analyzed. The immobilized culture of L. fermentum LA6 improved biodegradation of oxytetracycline in the wastewater. At 50 mg/L initial antibiotic concentration, 53.2 ± 2.8% oxytetracycline degradation was achieved, however, it improved at 200 mg/L antibiotic concentration in the culture medium (89.1 ± 4.3%) after 24 h. The chemical oxygen demand (COD) of the wastewater decreased significantly after treatment. At 200 mg/L oxytetracycline concentration, COD removal was considerably high (93.6 ± 5.3 mg/L) than 150 mg/L oxytetracycline concentration in the medium. Antibiotic removal efficiency in immobilized form revealed that this method is highly suitable for the removal of antibiotics from the wastewater.
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Affiliation(s)
- Amal M Al-Mohaimeed
- Department of Chemistry, College of Science, King Saud University, P.O. Box 22452, Riyadh, 11495, Saudi Arabia
| | - Arshad Mehmood Abbasi
- University of Gastronomic Sciences, 12042, Pollenzo, Italy; Department of Environmental Sciences, COMSATS University Islamabad, Abbottabad Campus, 22060, Abbottabad, Pakistan
| | - M Ajmal Ali
- Department of Botany and Microbiology, College of Science, King Saud University, Riyadh, 11451, Saudi Arabia
| | - D S Deepa Dhas
- Centre for Marine Science and Technology, Manonmaniam Sundaranar University, Tirunelveli, Tamilnadu, India.
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Maertens L, Matroule JY, Van Houdt R. Characteristics of the copper-induced viable-but-non-culturable state in bacteria. World J Microbiol Biotechnol 2021; 37:37. [PMID: 33544256 PMCID: PMC7864824 DOI: 10.1007/s11274-021-03006-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 01/17/2021] [Indexed: 02/06/2023]
Abstract
The antimicrobial applications of copper (Cu) are exploited in several industries, such as agriculture and healthcare settings. While Cu is capable of efficiently killing microorganisms, sub-lethal doses can induce a viable-but-non-culturable (VBNC) state in bacteria of many distinct clades. VBNC cells cannot be detected by standard culture-based detection methods, and can become a threat to plants and animals as they often retain virulent traits upon resuscitation. Here we discuss the putative mechanisms of the Cu-induced VBNC state. Common observations in Cu-induced VBNC cells include a cellular response to reactive oxygen species, the exhaustion of energy reserves, and a reconfiguration of the proteome. While showing partial overlap with other VBNC state-inducing stressors, these changes seem to be part of an adaptive response to Cu toxicity. Furthermore, we argue that Cu resistance mechanisms such as P-type ATPases and multicopper oxidases may ward off entry into the VBNC state to some extent. The spread of these mechanisms across multi-species populations could increase population-level resistance to Cu antimicrobials. As Cu resistance mechanisms are often co-selected with antibiotic resistance mechanisms, this threat is exacerbated.
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Affiliation(s)
- Laurens Maertens
- Microbiology Unit, Interdisciplinary Biosciences, Belgian Nuclear Research Centre (SCK CEN), Mol, Belgium.,Research Unit in Microorganisms Biology (URBM), Narilis Institute, University of Namur, Namur, Belgium
| | - Jean-Yves Matroule
- Research Unit in Microorganisms Biology (URBM), Narilis Institute, University of Namur, Namur, Belgium
| | - Rob Van Houdt
- Microbiology Unit, Interdisciplinary Biosciences, Belgian Nuclear Research Centre (SCK CEN), Mol, Belgium.
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Ni J, Liu Y, Shen C, Chen D, Xin Y, Liu Q. Bioinformatics, bacterial expression and enzyme activity analyses of dichloromethane dehalogenase from Methylobacterium rhodesianum H13. BIOTECHNOL BIOTEC EQ 2020. [DOI: 10.1080/13102818.2020.1818622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Affiliation(s)
- Jianguo Ni
- Department of Environmental Engineering, College of Life and Environmental Science, Hangzhou Normal University, Hangzhou, Zhejiang, PR China
- Department of Linpu Environmental Protection, Hangzhou Ecological Environment Bureau of Xiaoshan Branch, Hangzhou, Zhejiang, PR China
| | - Ying Liu
- Department of Environmental Engineering, College of Life and Environmental Science, Hangzhou Normal University, Hangzhou, Zhejiang, PR China
| | - Chenjia Shen
- Department of Environmental Engineering, College of Life and Environmental Science, Hangzhou Normal University, Hangzhou, Zhejiang, PR China
| | - Dongzhi Chen
- Department of Environmental Engineering, College of Environment, Zhejiang University of Technology, Hangzhou, Zhejiang, PR China
| | - Yueyong Xin
- Department of Environmental Engineering, College of Life and Environmental Science, Hangzhou Normal University, Hangzhou, Zhejiang, PR China
| | - Qi Liu
- Department of Environmental Engineering, College of Life and Environmental Science, Hangzhou Normal University, Hangzhou, Zhejiang, PR China
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Kumar SS, Ghosh AR. Assessment of bacterial viability: a comprehensive review on recent advances and challenges. Microbiology (Reading) 2019; 165:593-610. [DOI: 10.1099/mic.0.000786] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Affiliation(s)
- Shravanthi S. Kumar
- Department of Integrative Biology, School of Bio Sciences and Technology, Vellore Institute of Technology, Vellore-632014, Tamil Nadu, India
| | - Asit Ranjan Ghosh
- Department of Integrative Biology, School of Bio Sciences and Technology, Vellore Institute of Technology, Vellore-632014, Tamil Nadu, India
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Acinetobacter baumannii OxyR Regulates the Transcriptional Response to Hydrogen Peroxide. Infect Immun 2018; 87:IAI.00413-18. [PMID: 30297527 DOI: 10.1128/iai.00413-18] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Accepted: 10/03/2018] [Indexed: 12/21/2022] Open
Abstract
Acinetobacter baumannii is a Gram-negative opportunistic pathogen that causes diverse infections, including pneumonia, bacteremia, and wound infections. Due to multiple intrinsic and acquired antimicrobial-resistance mechanisms, A. baumannii isolates are commonly multidrug resistant, and infections are notoriously difficult to treat. The World Health Organization recently highlighted carbapenem-resistant A. baumannii as a "critical priority" for the development of new antimicrobials because of the risk to human health posed by this organism. Therefore, it is important to discover the mechanisms used by A. baumannii to survive stresses encountered during infection in order to identify new drug targets. In this study, by use of in vivo imaging, we identified hydrogen peroxide (H2O2) as a stressor produced in the lung during A. baumannii infection and defined OxyR as a transcriptional regulator of the H2O2 stress response. Upon exposure to H2O2, A. baumannii differentially transcribes several hundred genes. However, the transcriptional upregulation of genes predicted to detoxify hydrogen peroxide is abolished in an A. baumannii strain in which the transcriptional regulator oxyR is genetically inactivated. Moreover, inactivation of oxyR in both antimicrobial-susceptible and multidrug-resistant A. baumannii strains impairs growth in the presence of H2O2 OxyR is a direct regulator of katE and ahpF1, which encode the major H2O2-degrading enzymes in A. baumannii, as confirmed through measurement of promoter binding by recombinant OxyR in electromobility shift assays. Finally, an oxyR mutant is less fit than wild-type A. baumannii during infection of the murine lung. This work reveals a mechanism used by this important human pathogen to survive H2O2 stress encountered during infection.
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Dada N, Sheth M, Liebman K, Pinto J, Lenhart A. Whole metagenome sequencing reveals links between mosquito microbiota and insecticide resistance in malaria vectors. Sci Rep 2018; 8:2084. [PMID: 29391526 PMCID: PMC5794770 DOI: 10.1038/s41598-018-20367-4] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Accepted: 01/17/2018] [Indexed: 02/04/2023] Open
Abstract
In light of the declining global malaria burden attained largely due to insecticides, a deeper understanding of the factors driving insecticide resistance is needed to mitigate its growing threat to malaria vector control programs. Following evidence of microbiota-mediated insecticide resistance in agricultural pests, we undertook a comparative study of the microbiota in mosquitoes of differing insecticide resistance status. The microbiota of wild-caught Anopheles albimanus, an important Latin American malaria vector, that were resistant (FEN_Res) or susceptible (FEN_Sus) to the organophosphate (OP) insecticide fenitrothion were characterized and compared using whole metagenome sequencing. Results showed differing composition of the microbiota and its functions between FEN_Res and FEN_Sus, with significant enrichment of OP-degrading bacteria and enzymes in FEN_Res compared to FEN_Sus. Lower bacterial diversity was observed in FEN_Res compared to FEN_Sus, suggesting the enrichment of bacterial taxa with a competitive advantage in response to insecticide selection pressure. We report and characterize for the first time whole metagenomes of An. albimanus, revealing associations between the microbiota and phenotypic resistance to the insecticide fenitrothion. This study lays the groundwork for further investigation of the role of the mosquito microbiota in insecticide resistance.
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Affiliation(s)
- Nsa Dada
- Entomology Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, United States Centers for Disease Control and Prevention, 1600 Clifton RD. NE. MS G-49, Atlanta, GA 30329, United States of America
- American Society for Microbiology, 1752 N Street, N. W. Washington, D. C., 20036, United States of America
| | - Mili Sheth
- Biotechnology Core Facility Branch, Division of Scientific Resources, National Center for Emerging & Zoonotic Infectious Diseases, United States Centers for Disease Control and Prevention, 1600 Clifton RD. NE, Atlanta, GA 30329, United States of America
| | - Kelly Liebman
- Entomology Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, United States Centers for Disease Control and Prevention, 1600 Clifton RD. NE. MS G-49, Atlanta, GA 30329, United States of America
- Vector-Borne Disease Section, Division of Communicable Disease Control, Center for Infectious Diseases, California Department of Public Health, 850 Marina Bay Parkway, Richmond, CA 94804, United States of America
| | - Jesus Pinto
- Instituto Nacional de Salud, Avenida Defensores del Morro (Ex-Huaylas) 2268, Chorrillos, Lima, Peru
| | - Audrey Lenhart
- Entomology Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, United States Centers for Disease Control and Prevention, 1600 Clifton RD. NE. MS G-49, Atlanta, GA 30329, United States of America.
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Endogenous hydrogen peroxide increases biofilm formation by inducing exopolysaccharide production in Acinetobacter oleivorans DR1. Sci Rep 2016; 6:21121. [PMID: 26884212 PMCID: PMC4756669 DOI: 10.1038/srep21121] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Accepted: 01/05/2016] [Indexed: 12/15/2022] Open
Abstract
In this study, we investigated differentially expressed proteins in Acinetobacter oleivorans cells during planktonic and biofilm growth by using 2-dimensional gel electrophoresis combined with matrix-assisted laser desorption time-of-flight mass spectrometry. We focused on the role of oxidative stress resistance during biofilm formation using mutants defective in alkyl hydroperoxide reductase (AhpC) because its production in aged biofilms was enhanced compared to that in planktonic cells. Results obtained using an ahpC promoter-gfp reporter vector showed that aged biofilms expressed higher ahpC levels than planktonic cells at 48 h. However, at 24 h, ahpC expression was higher in planktonic cells than in biofilms. Deletion of ahpC led to a severe growth defect in rich media that was not observed in minimal media and promoted early biofilm formation through increased production of exopolysaccharide (EPS) and EPS gene expression. Increased endogenous H2O2 production in the ahpC mutant in rich media enhanced biofilm formation, and this enhancement was not observed in the presence of antioxidants. Exogenous addition of H2O2 promoted biofilm formation in wild type cells, which suggested that biofilm development is linked to defense against H2O2. Collectively, our data showed that EPS production caused by H2O2 stress enhances biofilm formation in A. oleivorans.
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Chakka D, Gudla R, Madikonda AK, Pandeeti EVP, Parthasarathy S, Nandavaram A, Siddavattam D. The Organophosphate Degradation (opd) Island-borne Esterase-induced Metabolic Diversion in Escherichia coli and Its Influence on p-Nitrophenol Degradation. J Biol Chem 2015; 290:29920-30. [PMID: 26453310 DOI: 10.1074/jbc.m115.661249] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2015] [Indexed: 02/04/2023] Open
Abstract
In previous studies of the organophosphate degradation gene cluster, we showed that expression of an open reading frame (orf306) present within the cluster in Escherichia coli allowed growth on p-nitrophenol (PNP) as sole carbon source. We have now shown that expression of orf306 in E. coli causes a dramatic up-regulation in genes coding for alternative carbon catabolism. The propionate, glyoxylate, and methylcitrate cycle pathway-specific enzymes are up-regulated along with hca (phenylpropionate) and mhp (hydroxyphenylpropionate) degradation operons. These hca and mhp operons play a key role in degradation of PNP, enabling E. coli to grow using it as sole carbon source. Supporting growth experiments, PNP degradation products entered central metabolic pathways and were incorporated into the carbon backbone. The protein and RNA samples isolated from E. coli (pSDP10) cells grown in (14)C-labeled PNP indicated incorporation of (14)C carbon, suggesting Orf306-dependent assimilation of PNP in E. coli cells.
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Affiliation(s)
- Deviprasanna Chakka
- From the Department of Animal Biology, School of Life Sciences, University of Hyderabad, Hyderabad 500 046, India
| | - Ramurthy Gudla
- From the Department of Animal Biology, School of Life Sciences, University of Hyderabad, Hyderabad 500 046, India
| | - Ashok Kumar Madikonda
- From the Department of Animal Biology, School of Life Sciences, University of Hyderabad, Hyderabad 500 046, India
| | - Emmanuel Vijay Paul Pandeeti
- From the Department of Animal Biology, School of Life Sciences, University of Hyderabad, Hyderabad 500 046, India
| | - Sunil Parthasarathy
- From the Department of Animal Biology, School of Life Sciences, University of Hyderabad, Hyderabad 500 046, India
| | - Aparna Nandavaram
- From the Department of Animal Biology, School of Life Sciences, University of Hyderabad, Hyderabad 500 046, India
| | - Dayananda Siddavattam
- From the Department of Animal Biology, School of Life Sciences, University of Hyderabad, Hyderabad 500 046, India
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Molecular mechanism involved in the response to hydrogen peroxide stress in Acinetobacter oleivorans DR1. Appl Microbiol Biotechnol 2015; 99:10611-26. [PMID: 26298700 DOI: 10.1007/s00253-015-6914-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Revised: 07/26/2015] [Accepted: 08/03/2015] [Indexed: 10/23/2022]
Abstract
Two-dimensional gel electrophoresis was conducted to investigate the effect of H2O2 on whole protein expression in Acinetobacter oleivorans DR1. Functional classification of 13 upregulated proteins using MALDI-TOF mass spectrometry showed relationships with oxidative stress, energy production and conversion, nucleotide and amino acid metabolism, membrane-related, ion transport, and chaperone-related functions. Alignment of OxyR-binding regions from Pseudomonas aeruginosa and Escherichia coli with promoters of identified proteins revealed that only ahpC, ahpF, and trxB (thioredoxin-disulfide reductase) genes, along with a newly found oprC (putative outer membrane receptor protein) gene, have OxyR-binding sites. The oxyR and ahpC mutants were more sensitive to H2O2 and showed growth defects in both nutritional and n-hexadecane-amended media. Four catalases present in the genome of A. oleivorans DR1 were not detected, which led us to confirm the expression and activity of those catalases in the presence of H2O2. The expression patterns of the four catalase genes differed at different concentrations of H2O2. Interestingly, the promoters of both known OxyR-controlled katG gene (AOLE_17390) and putative small catalase gene (AOLE_09800) have OxyR-binding sites. Gel-shift assay confirmed OxyR binding to the promoter regions of newly identified OxyR-controlled genes encoding OprC and a putative catalase. Hierarchical expression and OxyR-binding of several OxyR-controlled genes suggested that concentration is an important factor in inducing the set of genes under H2O2 stress.
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Li L, Mendis N, Trigui H, Oliver JD, Faucher SP. The importance of the viable but non-culturable state in human bacterial pathogens. Front Microbiol 2014; 5:258. [PMID: 24917854 PMCID: PMC4040921 DOI: 10.3389/fmicb.2014.00258] [Citation(s) in RCA: 532] [Impact Index Per Article: 53.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Accepted: 05/12/2014] [Indexed: 12/12/2022] Open
Abstract
Many bacterial species have been found to exist in a viable but non-culturable (VBNC) state since its discovery in 1982. VBNC cells are characterized by a loss of culturability on routine agar, which impairs their detection by conventional plate count techniques. This leads to an underestimation of total viable cells in environmental or clinical samples, and thus poses a risk to public health. In this review, we present recent findings on the VBNC state of human bacterial pathogens. The characteristics of VBNC cells, including the similarities and differences to viable, culturable cells and dead cells, and different detection methods are discussed. Exposure to various stresses can induce the VBNC state, and VBNC cells may be resuscitated back to culturable cells under suitable stimuli. The conditions that trigger the induction of the VBNC state and resuscitation from it are summarized and the mechanisms underlying these two processes are discussed. Last but not least, the significance of VBNC cells and their potential influence on human health are also reviewed.
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Affiliation(s)
- Laam Li
- Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University Ste-Anne-de-Bellevue, QC, Canada
| | - Nilmini Mendis
- Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University Ste-Anne-de-Bellevue, QC, Canada
| | - Hana Trigui
- Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University Ste-Anne-de-Bellevue, QC, Canada
| | - James D Oliver
- Department of Biology, University of North Carolina at Charlotte Charlotte, NC, USA
| | - Sebastien P Faucher
- Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University Ste-Anne-de-Bellevue, QC, Canada
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Hare JM, Ferrell JC, Witkowski TA, Grice AN. Prophage induction and differential RecA and UmuDAb transcriptome regulation in the DNA damage responses of Acinetobacter baumannii and Acinetobacter baylyi. PLoS One 2014; 9:e93861. [PMID: 24709747 PMCID: PMC3978071 DOI: 10.1371/journal.pone.0093861] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Accepted: 03/08/2014] [Indexed: 11/21/2022] Open
Abstract
The SOS response to DNA damage that induces up to 10% of the prokaryotic genome requires RecA action to relieve LexA transcriptional repression. In Acinetobacter species, which lack LexA, the error-prone polymerase accessory UmuDAb is instead required for ddrR induction after DNA damage, suggesting it might be a LexA analog. RNA-Seq experiments defined the DNA damage transcriptome (mitomycin C-induced) of wild type, recA and umuDAb mutant strains of both A. baylyi ADP1 and A. baumannii ATCC 17978. Of the typical SOS response genes, few were differentially regulated in these species; many were repressed or absent. A striking 38.4% of all ADP1 genes, and 11.4% of all 17978 genes, were repressed under these conditions. In A. baylyi ADP1, 66 genes (2.0% of the genome), including a CRISPR/Cas system, were DNA damage-induced, and belonged to four regulons defined by differential use of recA and umuDAb. In A. baumannii ATCC 17978, however, induction of 99% of the 152 mitomycin C-induced genes depended on recA, and only 28 of these genes required umuDAb for their induction. 90% of the induced A. baumannii genes were clustered in three prophage regions, and bacteriophage particles were observed after mitomycin C treatment. These prophages encoded esvI, esvK1, and esvK2, ethanol-stimulated virulence genes previously identified in a Caenorhabditis elegans model, as well as error-prone polymerase alleles. The induction of all 17978 error-prone polymerase alleles, whether prophage-encoded or not, was recA dependent, but only these DNA polymerase V-related genes were de-repressed in the umuDAb mutant in the absence of DNA damage. These results suggest that both species possess a robust and complex DNA damage response involving both recA-dependent and recA-independent regulons, and further demonstrates that although umuDAb has a specialized role in repressing error-prone polymerases, additional regulators likely participate in these species' transcriptional response to DNA damage.
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Affiliation(s)
- Janelle M. Hare
- Department of Biology and Chemistry, Morehead State University, Morehead, Kentucky, United States of America
- * E-mail:
| | - Joshua C. Ferrell
- Department of Biology and Chemistry, Morehead State University, Morehead, Kentucky, United States of America
| | - Travis A. Witkowski
- Department of Biology and Chemistry, Morehead State University, Morehead, Kentucky, United States of America
| | - Alison N. Grice
- Department of Biology and Chemistry, Morehead State University, Morehead, Kentucky, United States of America
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