1
|
Priya T T, Jacob JJ, M Y, Karthik R, Iyadurai R, G K, Devi B Y, Walia K, Veeraraghavan B. Is it time to move on to gene-based Salmonella typing: Evidence and implications. Indian J Med Microbiol 2023; 44:100359. [PMID: 37356840 DOI: 10.1016/j.ijmmb.2023.02.002] [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: 08/04/2022] [Revised: 01/31/2023] [Accepted: 02/03/2023] [Indexed: 06/27/2023]
Abstract
Non-typhoidal Salmonella (NTS) is the major cause of foodborne infections globally, with considerable morbidity and mortality. The accurate identification of Salmonella serovars is important in disease management and public health surveillance. However, traditional serotyping methods are laborious, time-consuming and may produce ambiguous results. In this study, we evaluated traditional serotyping and seven gene-based multilocus sequence typing (MLST) methods to determine the serogroups of Salmonella strains. This study analysis suggests that MLST based serotyping is accurate in serogroup identification and discrimination of Salmonella serovars compared to the traditional serotyping method and can be implemented in routine clinical practice.
Collapse
Affiliation(s)
- Tharani Priya T
- Department of Clinical Microbiology, Christian Medical College, Vellore, India
| | - Jobin John Jacob
- Department of Clinical Microbiology, Christian Medical College, Vellore, India
| | - Yesudoss M
- Department of Clinical Microbiology, Christian Medical College, Vellore, India
| | - Rajiv Karthik
- Department of Infectious Disease & Hospital Infection Control Committee, Christian Medical College, Vellore, India
| | - Ramya Iyadurai
- Department of Medicine, Unit V, Christian Medical College, Vellore, India
| | - Karthik G
- Department of Medicine, Unit V, Christian Medical College, Vellore, India
| | - Yamuna Devi B
- Department of Clinical Microbiology, Christian Medical College, Vellore, India
| | - Kamini Walia
- Division of Epidemiology & Communicable Diseases, Indian Council of Medical Research, New Delhi, India
| | | |
Collapse
|
2
|
Chandra K, Nair AV, Chatterjee R, Muralidhara P, Singh A, Kamanna S, Tatu US, Chakravortty D. Absence of proline-peptide transporter YjiY in Salmonella Typhimurium leads to secretion of factors which inhibits intra-species biofilm formation. Microbiol Res 2023; 273:127411. [PMID: 37285689 DOI: 10.1016/j.micres.2023.127411] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 05/12/2023] [Accepted: 05/14/2023] [Indexed: 06/09/2023]
Abstract
Salmonella is a genus of widely spread Gram negative, facultative anaerobic bacteria, which is known to cause ¼th of diarrheal morbidity and mortality globally. It causes typhoid fever and gastroenteritis by gaining access to the host gut through contaminated food and water. Salmonella utilizes its biofilm lifestyle to strongly resist antibiotics and persist in the host. Although biofilm removal or dispersal has been studied widely, the inhibition of the initiation of Salmonella Typhimurium (STM WT) biofilm remains elusive. This study demonstrates the anti-biofilm property of the cell-free supernatant obtained from a carbon-starvation induced proline peptide transporter mutant (STM ΔyjiY) strain. The STM ΔyjiY culture supernatant primarily inhibits biofilm initiation by regulating biofilm-associated transcriptional network that is reversed upon complementation (STM ΔyjiY:yjiY). We demonstrate that abundance of FlgM correlates with the absence of flagella in the STM ΔyjiY supernatant treated WT cells. NusG works synergistically with the global transcriptional regulator H-NS. Relatively low abundances of flavoredoxin, glutaredoxin, and thiol peroxidase might lead to accumulation of ROS within the biofilm, and subsequent toxicity in STM ΔyjiY supernatant. This work further suggests that targeting these oxidative stress relieving proteins might be a good choice to reduce Salmonella biofilm.
Collapse
Affiliation(s)
- Kasturi Chandra
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
| | - Abhilash Vijay Nair
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
| | - Ritika Chatterjee
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
| | - Prerana Muralidhara
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
| | - Anmol Singh
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
| | - Sathisha Kamanna
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Utpal S Tatu
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Dipshikha Chakravortty
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India; Adjunct Faculty, School of Biology, Indian Institute of Science Education and Research, Thiruvananthapuram, India.
| |
Collapse
|
3
|
Sánchez-Serrano A, Mejía L, Camaró ML, Ortolá-Malvar S, Llácer-Luna M, García-González N, González-Candelas F. Genomic Surveillance of Salmonella from the Comunitat Valenciana (Spain). Antibiotics (Basel) 2023; 12:antibiotics12050883. [PMID: 37237786 DOI: 10.3390/antibiotics12050883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2023] [Revised: 04/28/2023] [Accepted: 05/05/2023] [Indexed: 05/28/2023] Open
Abstract
Salmonella enterica subspecies enterica is one of the most important foodborne pathogens and the causative agent of salmonellosis, which affects both humans and animals producing numerous infections every year. The study and understanding of its epidemiology are key to monitoring and controlling these bacteria. With the development of whole-genome sequencing (WGS) technologies, surveillance based on traditional serotyping and phenotypic tests of resistance is being replaced by genomic surveillance. To introduce WGS as a routine methodology for the surveillance of food-borne Salmonella in the region, we applied this technology to analyze a set of 141 S. enterica isolates obtained from various food sources between 2010 and 2017 in the Comunitat Valenciana (Spain). For this, we performed an evaluation of the most relevant Salmonella typing methods, serotyping and sequence typing, using both traditional and in silico approaches. We extended the use of WGS to detect antimicrobial resistance determinants and predicted minimum inhibitory concentrations (MICs). Finally, to understand possible contaminant sources in this region and their relationship to antimicrobial resistance (AMR), we performed cluster detection combining single-nucleotide polymorphism (SNP) pairwise distances and phylogenetic and epidemiological data. The results of in silico serotyping with WGS data were highly congruent with those of serological analyses (98.5% concordance). Multi-locus sequence typing (MLST) profiles obtained with WGS information were also highly congruent with the sequence type (ST) assignment based on Sanger sequencing (91.9% coincidence). In silico identification of antimicrobial resistance determinants and minimum inhibitory concentrations revealed a high number of resistance genes and possible resistant isolates. A combined phylogenetic and epidemiological analysis with complete genome sequences revealed relationships among isolates indicative of possible common sources for isolates with separate sampling in time and space that had not been detected from epidemiological information. As a result, we demonstrate the usefulness of WGS and in silico methods to obtain an improved characterization of S. enterica enterica isolates, allowing better surveillance of the pathogen in food products and in potential environmental and clinical samples of related interest.
Collapse
Affiliation(s)
- Andrea Sánchez-Serrano
- Joint Research Unit "Infection and Public Health", FISABIO-University of Valencia, 46020 Valencia, Spain
| | - Lorena Mejía
- Joint Research Unit "Infection and Public Health", FISABIO-University of Valencia, 46020 Valencia, Spain
- Institute for Integrative Systems Biology (I2SysBio), CSIC-University of Valencia, 46980 Valencia, Spain
- Instituto de Microbiología, Colegio de Ciencias Biológicas y Ambientales, Universidad San Francisco de Quito, Quito 170901, Ecuador
| | | | | | | | - Neris García-González
- Joint Research Unit "Infection and Public Health", FISABIO-University of Valencia, 46020 Valencia, Spain
- Institute for Integrative Systems Biology (I2SysBio), CSIC-University of Valencia, 46980 Valencia, Spain
| | - Fernando González-Candelas
- Joint Research Unit "Infection and Public Health", FISABIO-University of Valencia, 46020 Valencia, Spain
- Institute for Integrative Systems Biology (I2SysBio), CSIC-University of Valencia, 46980 Valencia, Spain
- CIBER in Epidemiology and Public Health, 28029 Madrid, Spain
| |
Collapse
|
4
|
Leigh RJ, Corrigan A, Murphy RA, Walsh F. Effect of Mannan-rich fraction supplementation on commercial broiler intestinum tenue and cecum microbiota. Anim Microbiome 2022; 4:66. [PMID: 36536475 PMCID: PMC9762088 DOI: 10.1186/s42523-022-00208-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 10/15/2022] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND The broiler gastrointestinal microbiome is a potent flock performance modulator yet may also serve as a reservoir for pathogen entry into the food chain. The goal of this project was to characterise the effect of mannan rich fraction (MRF) supplementation on microbiome diversity and composition of the intestinum tenue and cecum of commercial broilers. This study also aimed to address some of the intrinsic biases that exist in microbiome studies which arise due to the extensive disparity in 16S rRNA gene copy numbers between bacterial species and due to large intersample variation. RESULTS We observed a divergent yet rich microbiome structure between different anatomical sites and observed the explicit effect MRF supplementation had on community structure, diversity, and pathogen modulation. Birds supplemented with MRF displayed significantly higher species richness in the cecum and significantly different bacterial community composition in each gastrointestinal (GI) tract section. Supplemented birds had lower levels of the zoonotic pathogens Escherichia coli and Clostridioides difficile across all three intestinum tenue sites highlighting the potential of MRF supplementation in maintaining food chain integrity. Higher levels of probiotic genera (eg. Lactobacillus and Blautia) were also noted in the MRF supplemented birds. Following MRF supplementation, the cecum displayed higher relative abundances of both short chain fatty acid (SFCA) synthesising bacteria and SCFA concentrations. CONCLUSIONS Mannan rich fraction addition has been observed to reduce the bioburden of pathogens in broilers and to promote greater intestinal tract microbial biodiversity. This study is the first, to our knowledge, to investigate the effect of mannan-rich fraction supplementation on the microbiome associated with different GI tract anatomical geographies. In addition to this novelty, this study also exploited machine learning and biostatistical techniques to correct the intrinsic biases associated with microbiome community studies to enable a more robust understanding of community structure.
Collapse
Affiliation(s)
- Robert J. Leigh
- grid.95004.380000 0000 9331 9029Antimicrobial Resistance and Microbiome Research Group, Department of Biology, Maynooth University, Co. Kildare, Ireland
| | - Aoife Corrigan
- grid.496915.6Alltech Inc. (Alltech European Bioscience Centre), Summerhill Road, Sarney, Dunboyne, Co. Meath, Ireland
| | - Richard A. Murphy
- grid.496915.6Alltech Inc. (Alltech European Bioscience Centre), Summerhill Road, Sarney, Dunboyne, Co. Meath, Ireland
| | - Fiona Walsh
- grid.95004.380000 0000 9331 9029Antimicrobial Resistance and Microbiome Research Group, Department of Biology, Maynooth University, Co. Kildare, Ireland
| |
Collapse
|
5
|
Distinct Potentially Adaptive Accumulation of Truncation Mutations in Salmonella enterica serovar Typhi and Salmonella enterica serovar Paratyphi A. Microbiol Spectr 2022; 10:e0196921. [PMID: 35467366 PMCID: PMC9241588 DOI: 10.1128/spectrum.01969-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Gene inactivation through the accumulation of truncation (or premature stop codon) mutations is a common mode of evolution in bacteria. It is frequently believed to result from reductive evolutionary processes allowing purging of superfluous traits. However, several works have demonstrated that, similar to the occurrences of inactivating nonsynonymous (i.e., amino acid replacement) mutations under positive selection pressures, truncation mutations can also be adaptive where specific traits deleterious in particular environmental conditions need to be inactivated for survival. Here, we performed a comparative analysis of genome-wide accumulation of truncation mutations in Salmonella enterica serovar Typhi and Salmonella enterica serovar Paratyphi A. Considering the known convergent evolutionary trajectories in these two serovars, we expected a strong overlap of truncated genes in S. Typhi and S. Paratyphi A, emerging through either reductive or adaptive dynamics. However, we detected a distinct set of core truncated genes encoding different overrepresented functional clusters in each serovar. In 54% and 28% truncated genes in S. Typhi and S. Paratyphi A, respectively, inactivating mutations were acquired by only different subsets of isolates, instead of all isolates analyzed for that serovar. Importantly, 62% truncated genes (P < 0.001) in S. Typhi and S. Paratyphi A were also targeted by convergent amino acid mutations in different serovars, suggesting those genes to be under selection pressures. Our findings indicate significant presence of potentially adaptive truncation mutations in conjunction with the ones emerging due to reductive evolution. Further experimental and large-scale bioinformatic studies are necessary to better explore the impact of such adaptive footprints of truncation mutations in the evolution of bacterial virulence. IMPORTANCE Detecting the adaptive mutations leading to gene inactivation or loss of function is crucial for understanding their contribution in the evolution of bacterial virulence and antibiotic resistance. Such inactivating mutations, apart from being of nonsynonymous (i.e., amino acid replacement) nature, can also be truncation mutations, abruptly trimming the length of encoded proteins. Importantly, the notion of reductive evolutionary dynamics is primarily accepted toward the accumulation of truncation mutations. However, our case study on S. Typhi and S. Paratyphi A, two human-restricted systemically invasive pathogens exerting similar clinical manifestations, indicated that a significant proportion of truncation mutations emerge from positive selection pressures. The candidate genes from our study will enable directed functional assays for deciphering the adaptive role of truncation mutations in S. Typhi and S. Paratyphi A pathogenesis. Also, our genome-level analytical approach will pave the way to understand the contribution of truncation mutations in the adaptive evolution of other bacterial pathogens.
Collapse
|
6
|
Chang D, Islam ZU, Zheng J, Zhao J, Cui X, Yu Z. Inhibitor tolerance and bioethanol fermentability of levoglucosan-utilizing Escherichia coli were enhanced by overexpression of stress-responsive gene ycfR: The proteomics-guided metabolic engineering. Synth Syst Biotechnol 2021; 6:384-395. [PMID: 34853817 PMCID: PMC8605246 DOI: 10.1016/j.synbio.2021.11.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 08/28/2021] [Accepted: 11/08/2021] [Indexed: 01/06/2023] Open
Abstract
Pretreatment of lignocellulosic biomass is crucial for the release of biofermentable sugars for biofuels production, which could greatly alleviate the burgeoning environment and energy crisis caused by the massive usage of traditional fossil fuels. Pyrolysis is a cost-saving pretreatment process that can readily decompose biomass into levoglucosan, a promising anhydrosugar; however, many undesired toxic compounds inhibitory to downstream microbial fermentation are also generated during the pyrolysis, immensely impeding the bioconversion of levoglucosan-containing pyrolysate. Here, we took the first insight into the proteomic responses of a levoglucosan-utilizing and ethanol-producing Escherichia coli to three representative biomass-derived inhibitors, identifying large amounts of differentially expressed proteins (DEPs) that could guide the downstream metabolic engineering for the development of inhibitor-resistant strains. Fifteen up- and eight down-regulated DEPs were further identified as the biomarker stress-responsive proteins candidate for cellular tolerance to multiple inhibitors. Among these biomarker proteins, YcfR exhibiting the highest expression fold-change level was chosen as the target of overexpression to validate proteomics results and develop robust strains with enhanced inhibitor tolerance and fermentation performance. Finally, based on four plasmid-borne genes encoding the levoglucosan kinase, pyruvate decarboxylase, alcohol dehydrogenase, and protein YcfR, a new recombinant strain E. coli LGE-ycfR was successfully created, showing much higher acetic acid-, furfural-, and phenol-tolerance levels compared to the control without overexpression of ycfR. The specific growth rate, final cell density, ethanol concentration, ethanol productivity, and levoglucosan consumption rate of the recombinant were also remarkably improved. From the proteomics-guided metabolic engineering and phenotypic observations, we for the first time corroborated that YcfR is a stress-induced protein responsive to multiple biomass-derived inhibitors, and also developed an inhibitors-resistant strain that could produce bioethanol from levoglucosan in the presence of inhibitors of relatively high concentration. The newly developed E. coli LGE-ycfR strain that could eliminate the commonly-used costly detoxicification processes, is of great potential for the in situ cost-effective bioethanol production from the biomass-derived pyrolytic substrates.
Collapse
Affiliation(s)
- Dongdong Chang
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, 100049, PR China
| | - Zia Ul Islam
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, 100049, PR China
- Department of Chemistry, Mississippi State University, Mississippi State, MS 39762, USA
| | - Junfang Zheng
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Capital Medical University, Beijing, 100069, PR China
| | - Jie Zhao
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, 100049, PR China
| | - Xiaoyong Cui
- Yanshan Earth Critical Zone and Surface Fluxes Research Station, Chinese Academy of Sciences, No. 380 Huaibei Town, Huairou District, Beijing, 101408, PR China
| | - Zhisheng Yu
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, 100049, PR China
- RCEES-IMCAS-UCAS Joint-Lab of Microbial Technology for Environmental Science, Beijing, 100085, PR China
- Corresponding author. College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, 100049, PR China.
| |
Collapse
|
7
|
Loose M, Sáez Moreno D, Mutti M, Hitzenhammer E, Visram Z, Dippel D, Schertler S, Tišáková LP, Wittmann J, Corsini L, Wagenlehner F. Natural Bred ε 2-Phages Have an Improved Host Range and Virulence against Uropathogenic Escherichia coli over Their Ancestor Phages. Antibiotics (Basel) 2021; 10:1337. [PMID: 34827275 PMCID: PMC8614997 DOI: 10.3390/antibiotics10111337] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 10/20/2021] [Accepted: 10/27/2021] [Indexed: 12/22/2022] Open
Abstract
Alternative treatments for Escherichia coli infections are urgently needed, and phage therapy is a promising option where antibiotics fail, especially for urinary tract infections (UTI). We used wastewater-isolated phages to test their lytic activity against a panel of 47 E. coli strains reflecting the diversity of strains found in UTI, including sequence type 131, 73 and 69. The plaquing host range (PHR) was between 13 and 63%. In contrast, the kinetic host range (KHR), describing the percentage of strains for which growth in suspension was suppressed for 24 h, was between 0% and 19%, substantially lower than the PHR. To improve the phage host range and their efficacy, we bred the phages by mixing and propagating cocktails on a subset of E. coli strains. The bred phages, which we termed evolution-squared ε2-phages, of a mixture of Myoviridae have KHRs up to 23% broader compared to their ancestors. Furthermore, using constant phage concentrations, Myoviridae ε2-phages suppressed the growth of higher bacterial inocula than their ancestors did. Thus, the ε2-phages were more virulent compared to their ancestors. Analysis of the genetic sequences of the ε2-phages with the broadest host range reveals that they are mosaic intercrossings of 2-3 ancestor phages. The recombination sites are distributed over the whole length of the genome. All ε2-phages are devoid of genes conferring lysogeny, antibiotic resistance, or virulence. Overall, this study shows that ε2-phages are remarkably more suitable than the wild-type phages for phage therapy.
Collapse
Affiliation(s)
- Maria Loose
- Clinic for Urology, Pediatric Urology and Andrology, Justus-Liebig University Giessen, 35392 Giessen, Germany; (M.L.); (D.D.)
| | - David Sáez Moreno
- PhagoMed Biopharma GmbH, A-1110 Vienna, Austria; (D.S.M.); (M.M.); (E.H.); (Z.V.); (L.P.T.)
| | - Michele Mutti
- PhagoMed Biopharma GmbH, A-1110 Vienna, Austria; (D.S.M.); (M.M.); (E.H.); (Z.V.); (L.P.T.)
| | - Eva Hitzenhammer
- PhagoMed Biopharma GmbH, A-1110 Vienna, Austria; (D.S.M.); (M.M.); (E.H.); (Z.V.); (L.P.T.)
| | - Zehra Visram
- PhagoMed Biopharma GmbH, A-1110 Vienna, Austria; (D.S.M.); (M.M.); (E.H.); (Z.V.); (L.P.T.)
| | - David Dippel
- Clinic for Urology, Pediatric Urology and Andrology, Justus-Liebig University Giessen, 35392 Giessen, Germany; (M.L.); (D.D.)
| | - Susanne Schertler
- DSMZ—German Collection of Microorganism and Cell Cultures GmbH, Leibniz Institute, 38124 Braunschweig, Germany; (S.S.); (J.W.)
| | - Lenka Podpera Tišáková
- PhagoMed Biopharma GmbH, A-1110 Vienna, Austria; (D.S.M.); (M.M.); (E.H.); (Z.V.); (L.P.T.)
- DSMZ—German Collection of Microorganism and Cell Cultures GmbH, Leibniz Institute, 38124 Braunschweig, Germany; (S.S.); (J.W.)
| | - Johannes Wittmann
- DSMZ—German Collection of Microorganism and Cell Cultures GmbH, Leibniz Institute, 38124 Braunschweig, Germany; (S.S.); (J.W.)
| | - Lorenzo Corsini
- PhagoMed Biopharma GmbH, A-1110 Vienna, Austria; (D.S.M.); (M.M.); (E.H.); (Z.V.); (L.P.T.)
| | - Florian Wagenlehner
- Clinic for Urology, Pediatric Urology and Andrology, Justus-Liebig University Giessen, 35392 Giessen, Germany; (M.L.); (D.D.)
| |
Collapse
|
8
|
Banerjee R, Chaudhari NM, Lahiri A, Gautam A, Bhowmik D, Dutta C, Chattopadhyay S, Huson DH, Paul S. Interplay of Various Evolutionary Modes in Genome Diversification and Adaptive Evolution of the Family Sulfolobaceae. Front Microbiol 2021; 12:639995. [PMID: 34248865 PMCID: PMC8267890 DOI: 10.3389/fmicb.2021.639995] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Accepted: 05/06/2021] [Indexed: 11/21/2022] Open
Abstract
Sulfolobaceae family, comprising diverse thermoacidophilic and aerobic sulfur-metabolizing Archaea from various geographical locations, offers an ideal opportunity to infer the evolutionary dynamics across the members of this family. Comparative pan-genomics coupled with evolutionary analyses has revealed asymmetric genome evolution within the Sulfolobaceae family. The trend of genome streamlining followed by periods of differential gene gains resulted in an overall genome expansion in some species of this family, whereas there was reduction in others. Among the core genes, both Sulfolobus islandicus and Saccharolobus solfataricus showed a considerable fraction of positively selected genes and also higher frequencies of gene acquisition. In contrast, Sulfolobus acidocaldarius genomes experienced substantial amount of gene loss and strong purifying selection as manifested by relatively lower genome size and higher genome conservation. Central carbohydrate metabolism and sulfur metabolism coevolved with the genome diversification pattern of this archaeal family. The autotrophic CO2 fixation with three significant positively selected enzymes from S. islandicus and S. solfataricus was found to be more imperative than heterotrophic CO2 fixation for Sulfolobaceae. Overall, our analysis provides an insight into the interplay of various genomic adaptation strategies including gene gain-loss, mutation, and selection influencing genome diversification of Sulfolobaceae at various taxonomic levels and geographical locations.
Collapse
Affiliation(s)
- Rachana Banerjee
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, Kolkata, India
| | - Narendrakumar M. Chaudhari
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, Kolkata, India
| | - Abhishake Lahiri
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, Kolkata, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - Anupam Gautam
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, Kolkata, India
- Department of Pharmacoinformatics, National Institute of Pharmaceutical Education and Research, Kolkata, India
| | - Debaleena Bhowmik
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, Kolkata, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - Chitra Dutta
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, Kolkata, India
| | - Sujay Chattopadhyay
- JIS Institute of Advanced Studies and Research, JIS University, Kolkata, India
| | - Daniel H. Huson
- Institute for Bioinformatics and Medical Informatics, University of Tübingen, Tübingen, Germany
- Cluster of Excellence: Controlling Microbes to Fight Infection, Tübingen, Germany
| | - Sandip Paul
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, Kolkata, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| |
Collapse
|
9
|
Escherichia coli Genomic Diversity within Extraintestinal Acute Infections Argues for Adaptive Evolution at Play. mSphere 2021; 6:6/1/e01176-20. [PMID: 33408235 PMCID: PMC7845604 DOI: 10.1128/msphere.01176-20] [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] [Indexed: 11/23/2022] Open
Abstract
Little is known about the dynamics of adaptation in acute bacterial infections. By sequencing multiple isolates from monoclonal extraintestinal Escherichia coli infections in several patients, we were able to uncover traces of selection taking place at short time scales compared to chronic infection. Adaptive processes in chronic bacterial infections are well described, but much less is known about the processes at play during acute infections. Here, by sequencing seven randomly selected isolates per patient, we analyzed Escherichia coli populations from three acute extraintestinal infections in adults (meningitis, pyelonephritis, and peritonitis), in which a high-mutation-rate isolate or mutator isolate was found. The isolates of single patients displayed between a few dozen and more than 200 independent mutations, with up to half being specific to the mutator isolate. Multiple signs of positive selection were evidenced: a high ratio of nonsynonymous to synonymous mutations (Ka/Ks ratio) and strong mutational convergence within and between patients, some of them at loci well known for their adaptive potential, such as rpoS, rbsR, fimH, and fliC. For all patients, the mutator isolate was likely due to a large deletion of a methyl-directed mismatch repair gene, and in two instances, the deletion extended to genes involved in some genetic convergence, suggesting potential coselection. Intrinsic extraintestinal virulence assessed in a mouse model of sepsis showed variable patterns of virulence ranging from non-mouse killer to mouse killer for the isolates from single patients. However, genomic signature and gene inactivation experiments did not establish a link between a single gene and the capacity to kill mice, highlighting the complex and multifactorial nature of the virulence. Altogether, these data indicate that E. coli isolates are adapting under strong selective pressure when colonizing an extraintestinal site. IMPORTANCE Little is known about the dynamics of adaptation in acute bacterial infections. By sequencing multiple isolates from monoclonal extraintestinal Escherichia coli infections in several patients, we were able to uncover traces of selection taking place at short time scales compared to chronic infection. High genomic diversity was observed in the patient isolates, with an excess of nonsynonymous mutations, and the comparison within and between different infections showed patterns of convergence at the gene level, both constituting strong signs of adaptation. The genes targeted were coding mostly for proteins involved in global regulation, metabolism, and adhesion/motility. Moreover, virulence assessed in a mouse model of sepsis was variable among the isolates of single patients, but this difference was left unexplained at the molecular level. This work gives us clues about the E. coli lifestyle transition between commensalism and pathogenicity.
Collapse
|
10
|
Srivastava A, Murugaiyan J, Garcia JAL, De Corte D, Hoetzinger M, Eravci M, Weise C, Kumar Y, Roesler U, Hahn MW, Grossart HP. Combined Methylome, Transcriptome and Proteome Analyses Document Rapid Acclimatization of a Bacterium to Environmental Changes. Front Microbiol 2020; 11:544785. [PMID: 33042055 PMCID: PMC7522526 DOI: 10.3389/fmicb.2020.544785] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2020] [Accepted: 08/18/2020] [Indexed: 11/13/2022] Open
Abstract
Polynucleobacter asymbioticus strain QLW-P1DMWA-1T represents a group of highly successful heterotrophic ultramicrobacteria that is frequently very abundant (up to 70% of total bacterioplankton) in freshwater habitats across all seven continents. This strain was originally isolated from a shallow Alpine pond characterized by rapid changes in water temperature and elevated UV radiation due to its location at an altitude of 1300 m. To elucidate the strain’s adjustment to fluctuating environmental conditions, we recorded changes occurring in its transcriptomic and proteomic profiles under contrasting experimental conditions by simulating thermal conditions in winter and summer as well as high UV irradiation. To analyze the potential connection between gene expression and regulation via methyl group modification of the genome, we also analyzed its methylome. The methylation pattern differed between the three treatments, pointing to its potential role in differential gene expression. An adaptive process due to evolutionary pressure in the genus was deduced by calculating the ratios of non-synonymous to synonymous substitution rates for 20 Polynucleobacter spp. genomes obtained from geographically diverse isolates. The results indicate purifying selection.
Collapse
Affiliation(s)
- Abhishek Srivastava
- Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Stechlin, Germany.,Department of Functional and Evolutionary Ecology, University of Vienna, Vienna, Austria
| | - Jayaseelan Murugaiyan
- Centre for Infectious Medicine, Institute for Animal Health and Environmental Hygiene, Freie Universität Berlin, Berlin, Germany.,Department of Biotechnology, SRM University-AP, Guntur, India
| | - Juan A L Garcia
- Department of Functional and Evolutionary Ecology, University of Vienna, Vienna, Austria
| | - Daniele De Corte
- Research and Development Center for Marine Biosciences, Japan Agency for Marine-Earth Science and Technology, Yokosuka, Japan
| | - Matthias Hoetzinger
- Department of Biology and Environmental Science, Linnaeus University, Kalmar, Sweden
| | - Murat Eravci
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - Christoph Weise
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - Yadhu Kumar
- Eurofins Genomics Europe Sequencing GmbH, Konstanz, Germany
| | - Uwe Roesler
- Centre for Infectious Medicine, Institute for Animal Health and Environmental Hygiene, Freie Universität Berlin, Berlin, Germany
| | - Martin W Hahn
- Research Department for Limnology, University of Innsbruck, Mondsee, Austria
| | - Hans-Peter Grossart
- Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Stechlin, Germany.,Institute for Biochemistry and Biology, Potsdam University, Potsdam, Germany
| |
Collapse
|
11
|
Jacob JJ, Rachel T, Shankar BA, Gunasekaran K, Iyadurai R, Anandan S, Veeraraghavan B. MLST based serotype prediction for the accurate identification of non typhoidal Salmonella serovars. Mol Biol Rep 2020; 47:7797-7803. [PMID: 33001311 DOI: 10.1007/s11033-020-05856-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Accepted: 09/21/2020] [Indexed: 12/13/2022]
Abstract
Traditional serotyping based on the phenotypic variation of O- and H-antigen remains as the gold-standard for the identification and classification of Salmonella isolates for last 70 years. Although this classification is a globally recognized nomenclature, huge diversity of Salmonella serotypes have made the serovar identification to be very complex. Seven gene multilocus sequence typing (MLST) on the other hand can provide serovar prediction as well as the evolutionary origin between the serovars. In this study non typhoidal Salmonella (NTS) strains (n = 45) isolated from clinical samples (blood, faeces and pus) were identified by traditional phenotypic serotyping and biochemical testing. All the tested Salmonella isolates were designated as serovar Typhimurium based on phenotyping. However, by MLST 60% (27/45) of the isolates were S. Typhimurium, 35.5% (16/45) were S. Agona (ST13), 2.2% (1/45) were S. Kentucky (ST198) and 2.2% (1/45) were S. Saintpaul (ST27). MLST analysis assigned S. Typhimurium isolates as ST36 (18/127), ST19 (7/27) and ST313 (2/27). Mismatches in serovar designation between MLST database and phenotypic serotyping can be due to the misinterpretation of phenotypic serotyping as the antigenic structures of S. Typhimurium, S. Agona differs by a surface antigen. MLST based phylogeny of study isolates showed clustering according to sequence types. Concordance between MLST based sequence type and phenotypic serotype is important to provide insights into genetic population structure of Salmonella.
Collapse
Affiliation(s)
- Jobin John Jacob
- Department of Clinical Microbiology, Christian Medical College and Hospital, Vellore, Tamil Nadu, 632004, India
| | - Tanya Rachel
- Department of Clinical Microbiology, Christian Medical College and Hospital, Vellore, Tamil Nadu, 632004, India
| | - Baby Abirami Shankar
- Department of Clinical Microbiology, Christian Medical College and Hospital, Vellore, Tamil Nadu, 632004, India
| | - Karthik Gunasekaran
- Department of Medicine, Christian Medical College and Hospital, Vellore, Tamil Nadu, 632004, India
| | - Ramya Iyadurai
- Department of Medicine, Christian Medical College and Hospital, Vellore, Tamil Nadu, 632004, India
| | - Shalini Anandan
- Department of Clinical Microbiology, Christian Medical College and Hospital, Vellore, Tamil Nadu, 632004, India
| | - Balaji Veeraraghavan
- Department of Clinical Microbiology, Christian Medical College and Hospital, Vellore, Tamil Nadu, 632004, India.
| |
Collapse
|
12
|
Rapaka RR, Wahid R, Fresnay S, Booth JS, Darton TC, Jones C, Waddington CS, Levine MM, Pollard AJ, Sztein MB. Human Salmonella Typhi exposure generates differential multifunctional cross-reactive T-cell memory responses against Salmonella Paratyphi and invasive nontyphoidal Salmonella. Clin Transl Immunology 2020; 9:e1178. [PMID: 33005416 PMCID: PMC7512505 DOI: 10.1002/cti2.1178] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 08/16/2020] [Accepted: 08/17/2020] [Indexed: 12/19/2022] Open
Abstract
Objective There are no vaccines for most of the major invasive Salmonella strains causing severe infection in humans. We evaluated the specificity of adaptive T memory cell responses generated after Salmonella Typhi exposure in humans against other major invasive Salmonella strains sharing capacity for dissemination. Methods T memory cells from eleven volunteers who underwent controlled oral challenge with wtS. Typhi were characterised by flow cytometry for cross‐reactive cellular cytokine/chemokine effector responses or evidence of degranulation upon stimulation with autologous B‐lymphoblastoid cells infected with either S. Typhi, Salmonella Paratyphi A (PA), S. Paratyphi B (PB) or an invasive nontyphoidal Salmonella strain of the S. Typhimurium serovar (iNTSTy). Results Blood T‐cell effector memory (TEM) responses after exposure to S. Typhi in humans evolve late, peaking weeks after infection in most volunteers. Induced multifunctional CD4+ Th1 and CD8+ TEM cells elicited after S. Typhi challenge were cross‐reactive with PA, PB and iNTSTy. The magnitude of multifunctional CD4+ TEM cell responses to S. Typhi correlated with induction of cross‐reactive multifunctional CD8+ TEM cells against PA, PB and iNTSTy. Highly multifunctional subsets and T central memory and T effector memory cells that re‐express CD45 (TEMRA) demonstrated less heterologous T‐cell cross‐reactivity, and multifunctional Th17 elicited after S. Typhi challenge was not cross‐reactive against other invasive Salmonella. Conclusion Gaps in cross‐reactive immune effector functions in human T‐cell memory compartments were highly dependent on invasive Salmonella strain, underscoring the importance of strain‐dependent vaccination in the design of T‐cell‐based vaccines for invasive Salmonella.
Collapse
Affiliation(s)
- Rekha R Rapaka
- Center for Vaccine Development and Global Health University of Maryland School of Medicine Baltimore MD USA.,Department of Medicine University of Maryland School of Medicine Baltimore MD USA
| | - Rezwanul Wahid
- Center for Vaccine Development and Global Health University of Maryland School of Medicine Baltimore MD USA.,Department of Pediatrics University of Maryland School of Medicine Baltimore MD USA
| | - Stephanie Fresnay
- Center for Vaccine Development and Global Health University of Maryland School of Medicine Baltimore MD USA.,Department of Pediatrics University of Maryland School of Medicine Baltimore MD USA.,Present address: Stephanie Fresnay GlaxoSmithKline Rockville MD USA
| | - Jayaum S Booth
- Center for Vaccine Development and Global Health University of Maryland School of Medicine Baltimore MD USA.,Department of Pediatrics University of Maryland School of Medicine Baltimore MD USA
| | - Thomas C Darton
- Oxford Vaccine Group Department of Paediatrics University of Oxford and the NIHR Oxford Biomedical Research Centre Oxford UK.,Present address: Thomas C Darton University of Sheffield Medical School Sheffield UK
| | - Claire Jones
- Oxford Vaccine Group Department of Paediatrics University of Oxford and the NIHR Oxford Biomedical Research Centre Oxford UK
| | - Claire S Waddington
- Oxford Vaccine Group Department of Paediatrics University of Oxford and the NIHR Oxford Biomedical Research Centre Oxford UK.,Present address: University of Cambridge Cambridge UK
| | - Myron M Levine
- Center for Vaccine Development and Global Health University of Maryland School of Medicine Baltimore MD USA.,Department of Medicine University of Maryland School of Medicine Baltimore MD USA.,Department of Pediatrics University of Maryland School of Medicine Baltimore MD USA
| | - Andrew J Pollard
- Oxford Vaccine Group Department of Paediatrics University of Oxford and the NIHR Oxford Biomedical Research Centre Oxford UK
| | - Marcelo B Sztein
- Center for Vaccine Development and Global Health University of Maryland School of Medicine Baltimore MD USA.,Department of Medicine University of Maryland School of Medicine Baltimore MD USA.,Department of Pediatrics University of Maryland School of Medicine Baltimore MD USA
| |
Collapse
|
13
|
Liao J, Orsi RH, Carroll LM, Kovac J, Ou H, Zhang H, Wiedmann M. Serotype-specific evolutionary patterns of antimicrobial-resistant Salmonella enterica. BMC Evol Biol 2019; 19:132. [PMID: 31226931 PMCID: PMC6588947 DOI: 10.1186/s12862-019-1457-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Accepted: 06/11/2019] [Indexed: 12/28/2022] Open
Abstract
Background The emergence of antimicrobial-resistant (AMR) strains of the important human and animal pathogen Salmonella enterica poses a growing threat to public health. Here, we studied the genome-wide evolution of 90 S. enterica AMR isolates, representing one host adapted serotype (S. Dublin) and two broad host range serotypes (S. Newport and S. Typhimurium). Results AMR S. Typhimurium had a large effective population size, a large and diverse genome, AMR profiles with high diversity, and frequent positive selection and homologous recombination. AMR S. Newport showed a relatively low level of diversity and a relatively clonal population structure. AMR S. Dublin showed evidence for a recent population bottleneck, and the genomes were characterized by a larger number of genes and gene ontology terms specifically absent from this serotype and a significantly higher number of pseudogenes as compared to other two serotypes. Approximately 50% of accessory genes, including specific AMR and putative prophage genes, were significantly over- or under-represented in a given serotype. Approximately 65% of the core genes showed phylogenetic clustering by serotype, including the AMR gene aac (6′)-Iaa. While cell surface proteins were shown to be the main target of positive selection, some proteins with possible functions in AMR and virulence also showed evidence for positive selection. Homologous recombination mainly acted on prophage-associated proteins. Conclusions Our data indicates a strong association between genome content of S. enterica and serotype. Evolutionary patterns observed in S. Typhimurium are consistent with multiple emergence events of AMR strains and/or ecological success of this serotype in different hosts or habitats. Evolutionary patterns of S. Newport suggested that antimicrobial resistance emerged in one single lineage, Lineage IIC. A recent population bottleneck and genome decay observed in AMR S. Dublin are congruent with its narrow host range. Finally, our results suggest the potentially important role of positive selection in the evolution of antimicrobial resistance, host adaptation and serotype diversification in S. enterica. Electronic supplementary material The online version of this article (10.1186/s12862-019-1457-5) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Jingqiu Liao
- Department of Food Science, 341 Stocking Hall, Cornell University, Ithaca, NY, 14853, USA.,Graduate Field of Microbiology, Cornell University, Ithaca, NY, 14853, USA
| | - Renato Hohl Orsi
- Department of Food Science, 341 Stocking Hall, Cornell University, Ithaca, NY, 14853, USA
| | - Laura M Carroll
- Department of Food Science, 341 Stocking Hall, Cornell University, Ithaca, NY, 14853, USA
| | - Jasna Kovac
- Department of Food Science, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Hongyu Ou
- School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Hailong Zhang
- Department of Computer Science & Engineering, Ohio State University, Columbus, OH, 43210, USA
| | - Martin Wiedmann
- Department of Food Science, 341 Stocking Hall, Cornell University, Ithaca, NY, 14853, USA.
| |
Collapse
|
14
|
Thomas AK, Preetha S, Omanakuttan A, Vidyullata L, Ashokan A, Rajachandran V, Chattopadhyay S. Mutational convergence acts as a major player in adaptive parallel evolution of Shigella spp. Sci Rep 2019; 9:3252. [PMID: 30824790 PMCID: PMC6397287 DOI: 10.1038/s41598-019-39810-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Accepted: 01/25/2019] [Indexed: 12/17/2022] Open
Abstract
Shigella spp., emerging from multiple origins of Escherichia coli, poses a significant health threat as a causative agent of bacillary dysentery. While multiple serotypes of four different species have evolved via independent lineages, Shigella spp. are designated as a single pathotype, primarily because of their common mode of pathogenesis. Convergent horizontal transfer events have so far been attributed to the commonalities in the evolution of virulence across diverse lineages. However, the role of mutational convergence in such parallel evolution is not yet well understood. Here we have carried out a genome-wide analysis of Shigella strains from all four species to detect the core genes (i.e. the ones present in all analyzed strains) acquiring convergent mutations of evolutionarily recent origin. Simulation studies show non-neutral accumulation of these convergent mutations across species, suggesting their adaptive role in the evolution of Shigella virulence. S. dysenteriae strain 197, representing highly virulent type 1 (Sd1) clone, carries excessively high number of core genes with recent convergent mutations compared to other analyzed strains. We propose that this high frequency of adaptive convergence in S. dysenteriae strain 197 could be linked to recent re-emergence of the Sd1 clone and its increased resistance to antimicrobials.
Collapse
Affiliation(s)
- Achsah K Thomas
- School of Biotechnology, Amrita Vishwa Vidyapeetham, Kollam, 690 525, Kerala, India
| | - Sruthy Preetha
- School of Biotechnology, Amrita Vishwa Vidyapeetham, Kollam, 690 525, Kerala, India
| | - Anjana Omanakuttan
- School of Biotechnology, Amrita Vishwa Vidyapeetham, Kollam, 690 525, Kerala, India
| | - Lakkaraju Vidyullata
- School of Biotechnology, Amrita Vishwa Vidyapeetham, Kollam, 690 525, Kerala, India
| | - Anjaly Ashokan
- School of Biotechnology, Amrita Vishwa Vidyapeetham, Kollam, 690 525, Kerala, India
| | - Vyshakh Rajachandran
- School of Biotechnology, Amrita Vishwa Vidyapeetham, Kollam, 690 525, Kerala, India
| | - Sujay Chattopadhyay
- School of Biotechnology, Amrita Vishwa Vidyapeetham, Kollam, 690 525, Kerala, India.
| |
Collapse
|
15
|
Chattopadhyay S, Chi PB, Minin VN, Berg DE, Sokurenko EV. Recombination-independent rapid convergent evolution of the gastric pathogen Helicobacter pylori. BMC Genomics 2018; 19:835. [PMID: 30463511 PMCID: PMC6249973 DOI: 10.1186/s12864-018-5231-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2018] [Accepted: 11/07/2018] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Helicobacter pylori is a human stomach pathogen, naturally-competent for DNA uptake, and prone to homologous recombination. Extensive homoplasy (i.e., phylogenetically-unlinked identical variations) observed in H. pylori genes is considered a hallmark of such recombination. However, H. pylori also exhibits a high mutation rate. The relative adaptive role of homologous recombination and mutation in species diversity is a highly-debated issue in biology. Recombination results in homoplasy. While convergent mutation can also account for homoplasy, its contribution is thought to be minor. We demonstrate here that, contrary to dogma, convergent mutation is a key contributor to Helicobacter pylori homoplasy, potentially driven by adaptive evolution of proteins. RESULTS Our present genome-wide analysis shows that homoplastic nonsynonymous (amino acid replacement) changes are not typically accompanied by homoplastic synonymous (silent) variations. Moreover, the majority of the codon positions with homoplastic nonsynonymous changes also contain different (i.e. non-homoplastic) nonsynonymous changes arising from mutation only. This indicates that, to a considerable extent, nonsynonymous homoplasy is due to convergent mutations. High mutation rate or limited availability of evolvable sites cannot explain this excessive convergence, as suggested by our simulation studies. Rather, the genes with convergent mutations are overrepresented in distinct functional categories, suggesting possible selective responses to conditions such as distinct micro-niches in single hosts, and to differences in host genotype, physiology, habitat and diet. CONCLUSIONS We propose that mutational convergence is a key player in H. pylori's adaptation and extraordinary persistence in human hosts. High frequency of mutational convergence could be due to saturation of evolvable sites capable of responding to selection pressures, while the number of mutable residues is far from saturation. We anticipate a similar scenario of mutational vs. recombinational genome dynamics or plasticity for other naturally competent microbes where strong positive selection could favor frequent convergent mutations in adaptive protein evolution.
Collapse
Affiliation(s)
| | - Peter B Chi
- Department of Mathematics and Statistics, Villanova University, Villanova, PA, USA
| | - Vladimir N Minin
- Department of Statistics, University of California, Irvine, California, USA
| | - Douglas E Berg
- Division of Infectious Diseases, Department of Medicine, University of California, San Diego, La Jolla, California, USA
| | - Evgeni V Sokurenko
- Department of Microbiology, University of Washington, Seattle, Washington, USA
| |
Collapse
|
16
|
Viana MVC, Sahm A, Góes Neto A, Figueiredo HCP, Wattam AR, Azevedo V. Rapidly evolving changes and gene loss associated with host switching in Corynebacterium pseudotuberculosis. PLoS One 2018; 13:e0207304. [PMID: 30419061 PMCID: PMC6231662 DOI: 10.1371/journal.pone.0207304] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Accepted: 10/28/2018] [Indexed: 02/01/2023] Open
Abstract
Phylogenomics and genome scale positive selection analyses were performed on 29 Corynebacterium pseudotuberculosis genomes that were isolated from different hosts, including representatives of the Ovis and Equi biovars. A total of 27 genes were identified as undergoing adaptive changes. An analysis of the clades within this species and these biovars, the genes specific to each branch, and the genes responding to selective pressure show clear differences, indicating that adaptation and specialization is occurring in different clades. These changes are often correlated with the isolation host but could indicate responses to some undetermined factor in the respective niches. The fact that some of these more-rapidly evolving genes have homology to known virulence factors, antimicrobial resistance genes and drug targets shows that this type of analysis could be used to identify novel targets, and that these could be used as a way to control this pathogen.
Collapse
Affiliation(s)
| | - Arne Sahm
- Leibniz Institute on Aging, Fritz Lipmann Institute, Jena, Germany
| | - Aristóteles Góes Neto
- Department of Microbiology, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Henrique Cesar Pereira Figueiredo
- AQUACEN, National Reference Laboratory for Aquatic Animal Diseases, Ministry of Fisheries and Aquaculture, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Alice Rebecca Wattam
- Biocomplexity Institute of Virginia Tech, Virginia Tech, Blacksburg, Virginia, United States of America
| | - Vasco Azevedo
- Department of General Biology, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| |
Collapse
|
17
|
Oladeinde A, Cook K, Orlek A, Zock G, Herrington K, Cox N, Plumblee Lawrence J, Hall C. Hotspot mutations and ColE1 plasmids contribute to the fitness of Salmonella Heidelberg in poultry litter. PLoS One 2018; 13:e0202286. [PMID: 30169497 PMCID: PMC6118388 DOI: 10.1371/journal.pone.0202286] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Accepted: 07/31/2018] [Indexed: 12/14/2022] Open
Abstract
Salmonella enterica subsp. enterica serovar Heidelberg (S. Heidelberg) is a clinically-important serovar linked to food-borne illness, and commonly isolated from poultry. Investigations of a large, multistate outbreak in the USA in 2013 identified poultry litter (PL) as an important extra-intestinal environment that may have selected for specific S. Heidelberg strains. Poultry litter is a mixture of bedding materials and chicken excreta that contains chicken gastrointestinal (GI) bacteria, undigested feed, feathers, and other materials of chicken origin. In this study, we performed a series of controlled laboratory experiments which assessed the microevolution of two S. Heidelberg strains (SH-2813 and SH-116) in PL previously used to raise 3 flocks of broiler chickens. The strains are closely related at the chromosome level, differing from the reference genome by 109 and 89 single nucleotide polymorphisms/InDels, respectively. Whole genome sequencing was performed on 86 isolates recovered after 0, 1, 7 and 14 days of microevolution in PL. Only strains carrying an IncX1 (37kb), 2 ColE1 (4 and 6kb) and 1 ColpVC (2kb) plasmids survived more than 7 days in PL. Competition experiments showed that carriage of these plasmids was associated with increased fitness. This increased fitness was associated with an increased copy number of IncX1 and ColE1 plasmids. Further, all Col plasmid-bearing strains had hotspot mutations in 37 loci on the chromosome and in 3 loci on the IncX1 plasmid. Additionally, we observed a decrease in susceptibility to tobramycin, kanamycin, gentamicin, neomycin and fosfomycin for Col plasmid-bearing strains. Our study demonstrates how positive selection from poultry litter can change the evolutionary path of S. Heidelberg.
Collapse
Affiliation(s)
- Adelumola Oladeinde
- Bacterial Epidemiology and Antimicrobial Resistance Research Unit, U.S. National Poultry Research Center, USDA-ARS, Athens, GA, United States of America
| | - Kimberly Cook
- Bacterial Epidemiology and Antimicrobial Resistance Research Unit, U.S. National Poultry Research Center, USDA-ARS, Athens, GA, United States of America
| | - Alex Orlek
- Nuffield Department of Medicine, John Radcliffe Hospital, University of Oxford, Oxford, United Kingdom
| | - Greg Zock
- Bacterial Epidemiology and Antimicrobial Resistance Research Unit, U.S. National Poultry Research Center, USDA-ARS, Athens, GA, United States of America
| | - Kyler Herrington
- Department of Microbiology, University of Georgia, Athens, GA, United States of America
| | - Nelson Cox
- Poultry Microbiological Safety and Processing Research Unit, U.S. National Poultry Research Center, USDA-ARS, Athens, GA, United States of America
| | - Jodie Plumblee Lawrence
- Bacterial Epidemiology and Antimicrobial Resistance Research Unit, U.S. National Poultry Research Center, USDA-ARS, Athens, GA, United States of America
| | - Carolina Hall
- Bacterial Epidemiology and Antimicrobial Resistance Research Unit, U.S. National Poultry Research Center, USDA-ARS, Athens, GA, United States of America
| |
Collapse
|
18
|
Tanner JR, Kingsley RA. Evolution of Salmonella within Hosts. Trends Microbiol 2018; 26:986-998. [PMID: 29954653 PMCID: PMC6249985 DOI: 10.1016/j.tim.2018.06.001] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Revised: 05/22/2018] [Accepted: 06/01/2018] [Indexed: 11/18/2022]
Abstract
Within-host evolution has resulted in thousands of variants of Salmonella that exhibit remarkable diversity in host range and disease outcome, from broad host range to exquisite host restriction, causing gastroenteritis to disseminated disease such as typhoid fever. Within-host evolution is a continuing process driven by genomic variation that occurs during each infection, potentiating adaptation to a new niche resulting from changes in animal husbandry, the use of antimicrobials, and emergence of immune compromised populations. We discuss key advances in our understanding of the evolution of Salmonella within the host, inferred from (i) the process of host adaptation of Salmonella pathovars in the past, and (ii) direct observation of the generation of variation and selection of beneficial traits during single infections. Salmonella is a bacterial pathogen with remarkable diversity in its host range and pathogenicity due to past within-host evolution in vertebrate species that modified ancestral mechanisms of pathogenesis. Variation arising during infection includes point mutations, new genes acquired through horizontal gene transfer (HGT), deletions, and genomic rearrangements. Beneficial mutations increase in frequency within the host and, if they retain the ability to be transmitted to subsequent hosts, may become fixed in the population. Whole-genome sequencing of sequential isolates from clinical infections reveals within-host HGT and point mutations that impact therapy and clinical management. HGT is the primary mechanism for evolution in prokaryotes and is synergised by complex networks of transfer involving the microbiome. Within-host evolution of Salmonella, resulting in new pathovars, can proceed in the absence of HGT.
Collapse
Affiliation(s)
- Jennifer R Tanner
- Quadram Institute Bioscience, Norwich Research Park, Colney, Norwich, UK
| | - Robert A Kingsley
- Quadram Institute Bioscience, Norwich Research Park, Colney, Norwich, UK.
| |
Collapse
|
19
|
Abstract
Uropathogenic Escherichia coli (UPEC) are opportunistic human pathogens that primarily circulate as part of commensal intestinal microbiota. Though they have the ability to survive and proliferate in various urinary tract compartments, the urinary tract is a transient, occasional habitat for UPEC. Because of this, most of the UPEC traits have originally evolved to serve in intestinal colonization and transmission. Some of these bacterial traits serve as virulence factors - they are critical to or assist in survival of UPEC as pathogens, and the structure and/or function may be specialized for the infection. Other traits could serve as anti-virulence factors - they represent liability in the urinary tract and are under selection to be lost or inactivated during the infection. Inactivation, variation, or other changes of the bacterial genes that increase the pathogen's fitness during the infection are called pathoadaptive mutations. This chapter describes examples of pathoadaptive mutations in UPEC and provides rationale for their further in-depth study.
Collapse
|
20
|
Maddamsetti R, Hatcher PJ, Green AG, Williams BL, Marks DS, Lenski RE. Core Genes Evolve Rapidly in the Long-Term Evolution Experiment with Escherichia coli. Genome Biol Evol 2017; 9:1072-1083. [PMID: 28379360 PMCID: PMC5406848 DOI: 10.1093/gbe/evx064] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/03/2017] [Indexed: 12/22/2022] Open
Abstract
Bacteria can evolve rapidly under positive selection owing to their vast numbers, allowing their genes to diversify by adapting to different environments. We asked whether the same genes that evolve rapidly in the long-term evolution experiment (LTEE) with Escherichia coli have also diversified extensively in nature. To make this comparison, we identified ∼2000 core genes shared among 60 E. coli strains. During the LTEE, core genes accumulated significantly more nonsynonymous mutations than flexible (i.e., noncore) genes. Furthermore, core genes under positive selection in the LTEE are more conserved in nature than the average core gene. In some cases, adaptive mutations appear to modify protein functions, rather than merely knocking them out. The LTEE conditions are novel for E. coli, at least in relation to its evolutionary history in nature. The constancy and simplicity of the environment likely favor the complete loss of some unused functions and the fine-tuning of others.
Collapse
Affiliation(s)
- Rohan Maddamsetti
- Ecology, Evolutionary Biology, and Behavior Program, Michigan State University, East Lansing, MI.,BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI.,Department of Systems Biology, Harvard Medical School, Boston, MA
| | - Philip J Hatcher
- Department of Computer Science, University of New Hampshire, Durham, NH
| | - Anna G Green
- Department of Systems Biology, Harvard Medical School, Boston, MA
| | - Barry L Williams
- Ecology, Evolutionary Biology, and Behavior Program, Michigan State University, East Lansing, MI
| | - Debora S Marks
- Department of Systems Biology, Harvard Medical School, Boston, MA
| | - Richard E Lenski
- Ecology, Evolutionary Biology, and Behavior Program, Michigan State University, East Lansing, MI.,BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI
| |
Collapse
|
21
|
Merrikh H. Spatial and Temporal Control of Evolution through Replication-Transcription Conflicts. Trends Microbiol 2017; 25:515-521. [PMID: 28216294 DOI: 10.1016/j.tim.2017.01.008] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 01/10/2017] [Accepted: 01/27/2017] [Indexed: 01/16/2023]
Abstract
Evolution could potentially be accelerated if an organism could selectively increase the mutation rate of specific genes that are actively under positive selection. Recently, a mechanism that cells can use to target rapid evolution to specific genes was discovered. This mechanism is driven by gene orientation-dependent encounters between DNA replication and transcription machineries. These encounters increase mutagenesis in lagging-strand genes, where replication-transcription conflicts are severe. Due to the orientation and transcription-dependent nature of this process, conflict-driven mutagenesis can be used by cells to spatially (gene-specifically) and temporally (only upon transcription induction) regulate the rate of gene evolution. Here, I summarize recent findings on this topic, and discuss the implications of increasing mutagenesis rates and accelerating evolution through active mechanisms.
Collapse
Affiliation(s)
- Houra Merrikh
- Department of Microbiology, Health Sciences Building - J-wing, University of Washington, Seattle, WA 98195, USA.
| |
Collapse
|
22
|
Paul S, Minnick MF, Chattopadhyay S. Mutation-Driven Divergence and Convergence Indicate Adaptive Evolution of the Intracellular Human-Restricted Pathogen, Bartonella bacilliformis. PLoS Negl Trop Dis 2016; 10:e0004712. [PMID: 27167125 PMCID: PMC4864206 DOI: 10.1371/journal.pntd.0004712] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Accepted: 04/24/2016] [Indexed: 02/06/2023] Open
Abstract
Among all species of Bartonella, human-restricted Bartonella bacilliformis is the most virulent but harbors one of the most reduced genomes. Carrión’s disease, the infection caused by B. bacilliformis, has been afflicting poor rural populations for centuries in the high-altitude valleys of the South American Andes, where the pathogen’s distribution is probably restricted by its sand fly vector’s range. Importantly, Carrión’s disease satisfies the criteria set by the World Health Organization for a disease amenable to elimination. However, to date, there are no genome-level studies to identify potential footprints of B. bacilliformis (patho)adaptation. Our comparative genomic approach demonstrates that the evolution of this intracellular pathogen is shaped predominantly via mutation. Analysis of strains having publicly-available genomes shows high mutational divergence of core genes leading to multiple sub-species. We infer that the sub-speciation event might have happened recently where a possible adaptive divergence was accelerated by intermediate emergence of a mutator phenotype. Also, within a sub-species the pathogen shows inter-clonal adaptive evolution evidenced by non-neutral accumulation of convergent amino acid mutations. A total of 67 non-recombinant core genes (over-representing functional categories like DNA repair, glucose metabolic process, ATP-binding and ligase) were identified as candidates evolving via adaptive mutational convergence. Such convergence, both at the level of genes and their encoded functions, indicates evolution of B. bacilliformis clones along common adaptive routes, while there was little diversity within a single clone. How host-restriction, intracellularity and genome reduction interplay to exert or maintain virulence is poorly characterized. The fact that B. bacilliformis is the most pathogenic Bartonella and has a highly reduced genome makes it an attractive model to gain insights into (patho)adaptive evolution of intracellular pathogens. Also, B. bacilliformis is known to lack many virulence genes present in other Bartonella, indicating unique strategies of (patho)adaptation. Our study reveals a prevalent nature of mutational force in B. bacilliformis evolution with two distinct outcomes: (a) mutational divergence leading to sub-speciation, possibly recently, via accelerated accumulation and fixation of favorable mutations mediated by a mutator phenotype; and (b) mutational convergence between clones of a sub-species exhibiting shared functional trajectories of adaptive evolution. Our findings highlight positions accumulating adaptive mutations in candidate genes, offering future functional studies to elucidate B. bacilliformis virulence evolution, and of broad application to intracellular pathogens with a reduced gene repertoire.
Collapse
Affiliation(s)
- Sandip Paul
- Department of Microbiology, University of Washington, Seattle, Washington, United States of America
| | - Michael F. Minnick
- Division of Biological Sciences, University of Montana, Missoula, Montana, United States of America
| | - Sujay Chattopadhyay
- Department of Microbiology, University of Washington, Seattle, Washington, United States of America
- * E-mail:
| |
Collapse
|
23
|
Lee CA, Yeh KS. The Non-Fimbriate Phenotype Is Predominant among Salmonella enterica Serovar Choleraesuis from Swine and Those Non-Fimbriate Strains Possess Distinct Amino Acid Variations in FimH. PLoS One 2016; 11:e0151126. [PMID: 26974320 PMCID: PMC4790892 DOI: 10.1371/journal.pone.0151126] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Accepted: 02/24/2016] [Indexed: 11/22/2022] Open
Abstract
Although most Salmonella serovars are able to infect a range of animal hosts, some have acquired the ability to cause systemic infections of specific hosts. For example, Salmonella enterica serovar Choleraesuis is primarily associated with systemic infection in swine. Adherence to host epithelial cells is considered a prerequisite for initial infection, and fimbrial appendages on the outer membrane of the bacteria are implicated in this process. Although type 1 fimbriae encoded by the fim gene cluster are commonly found in Salmonella serovars, it is not known whether S. Choleraesuis produces this fimbrial type and if and how fimbriae are involved in pathogenesis. In the present study, we demonstrated that only four out of 120 S. Choleraesuis isolates from pigs with salmonellosis produced type 1 fimbriae as assayed by the yeast agglutination test and electron microscopy. One of the 116 non-type 1 fimbria-producing isolates was transformed with plasmids carrying different fim genes from S. Typhimurium LB5010, a type 1 fimbria-producing strain. Our results indicate that non-type 1 fimbria-producing S. Choleraesuis required only an intact fimH to regain the ability to produce fimbrial appendages. Sequence comparison revealed six amino acid variations between the FimH of the non-type 1 fimbria-producing S. Choleraesuis isolates and those of the type 1 fimbria-producing S. Choleraesuis isolates. S. Choleraesuis that produced type 1 fimbriae contained FimH with an amino acid sequence identical to that of S. Typhimurium LB5010. Site-directed mutagenesis leading to the replacement of the non-conserved residues revealed that a change from glycine to valine at position of 63 (G63V) resulted in a non-type 1 fimbria-producing S. Choleraesuis being able to express type 1 fimbriae on its outer membrane. It is possible that this particular amino acid change prevents this polypeptide from proper interaction with other Fim subunits required for assembly of an intact type 1 fimbrial shaft in S. Choleraesuis; however, it remains to be determined if and how the absence of type 1 fimbriae production is related to the systemic infection of the swine host by S. Choleraesuis.
Collapse
Affiliation(s)
- Chien-An Lee
- Department of Veterinary Medicine, School of Veterinary Medicine, College of Bio-Resources and Agriculture, National Taiwan University, Taipei, Taiwan
| | - Kuang-Sheng Yeh
- Department of Veterinary Medicine, School of Veterinary Medicine, College of Bio-Resources and Agriculture, National Taiwan University, Taipei, Taiwan
- National Taiwan University Veterinary Hospital, Taipei, Taiwan
- * E-mail:
| |
Collapse
|
24
|
PanCoreGen - Profiling, detecting, annotating protein-coding genes in microbial genomes. Genomics 2015; 106:367-72. [PMID: 26456591 DOI: 10.1016/j.ygeno.2015.10.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 09/24/2015] [Accepted: 10/03/2015] [Indexed: 11/20/2022]
Abstract
A large amount of genomic data, especially from multiple isolates of a single species, has opened new vistas for microbial genomics analysis. Analyzing the pan-genome (i.e. the sum of genetic repertoire) of microbial species is crucial in understanding the dynamics of molecular evolution, where virulence evolution is of major interest. Here we present PanCoreGen - a standalone application for pan- and core-genomic profiling of microbial protein-coding genes. PanCoreGen overcomes key limitations of the existing pan-genomic analysis tools, and develops an integrated annotation-structure for a species-specific pan-genomic profile. It provides important new features for annotating draft genomes/contigs and detecting unidentified genes in annotated genomes. It also generates user-defined group-specific datasets within the pan-genome. Interestingly, analyzing an example-set of Salmonella genomes, we detect potential footprints of adaptive convergence of horizontally transferred genes in two human-restricted pathogenic serovars - Typhi and Paratyphi A. Overall, PanCoreGen represents a state-of-the-art tool for microbial phylogenomics and pathogenomics study.
Collapse
|
25
|
Loss of the lac Operon Contributes to Salmonella Invasion of Epithelial Cells Through Derepression of Flagellar Synthesis. Curr Microbiol 2014; 70:315-23. [DOI: 10.1007/s00284-014-0720-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2014] [Accepted: 09/18/2014] [Indexed: 12/12/2022]
|
26
|
Transient Darwinian selection in Salmonella enterica serovar Paratyphi A during 450 years of global spread of enteric fever. Proc Natl Acad Sci U S A 2014; 111:12199-204. [PMID: 25092320 DOI: 10.1073/pnas.1411012111] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Multiple epidemic diseases have been designated as emerging or reemerging because the numbers of clinical cases have increased. Emerging diseases are often suspected to be driven by increased virulence or fitness, possibly associated with the gain of novel genes or mutations. However, the time period over which humans have been afflicted by such diseases is only known for very few bacterial pathogens, and the evidence for recently increased virulence or fitness is scanty. Has Darwinian (diversifying) selection at the genomic level recently driven microevolution within bacterial pathogens of humans? Salmonella enterica serovar Paratyphi A is a major cause of enteric fever, with a microbiological history dating to 1898. We identified seven modern lineages among 149 genomes on the basis of 4,584 SNPs in the core genome and estimated that Paratyphi A originated 450 y ago. During that time period, the effective population size has undergone expansion, reduction, and recent expansion. Mutations, some of which inactivate genes, have occurred continuously over the history of Paratyphi A, as has the gain or loss of accessory genes. We also identified 273 mutations that were under Darwinian selection. However, most genetic changes are transient, continuously being removed by purifying selection, and the genome of Paratyphi A has not changed dramatically over centuries. We conclude that Darwinian selection is not responsible for increased frequency of enteric fever and suggest that environmental changes may be more important for the frequency of disease.
Collapse
|
27
|
Chattopadhyay S, Taub F, Paul S, Weissman SJ, Sokurenko EV. Microbial variome database: point mutations, adaptive or not, in bacterial core genomes. Mol Biol Evol 2013; 30:1465-70. [PMID: 23493258 DOI: 10.1093/molbev/mst048] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Analysis of genetic differences (gene presence/absence and nucleotide polymorphisms) among strains of a bacterial species is crucial to understanding molecular mechanisms of bacterial pathogenesis and selecting targets for novel antibacterial therapeutics. However, lack of genome-wide association studies on large and epidemiologically well-defined strain collections from the same species makes it difficult to identify the genes under positive selection and define adaptive polymorphisms in those genes. To address this need and to overcome existing limitations, we propose to create a "microbial variome"--a species-specific resource database of genomic variations based on molecular evolutionary analysis. Here, we present prototype variome databases of Escherichia coli and Salmonella enterica subspecies enterica (http://depts.washington.edu/sokurel/variome, last accessed March 26, 2013). The prototypes currently include the point mutations data of core protein-coding genes from completely sequenced genomes of 22 E. coli and 17 S. enterica strains. These publicly available databases allow for single- and multiple-field sorting, filtering, and searching of the gene variability data and the potential adaptive significance. Such resource databases would immensely help experimental research, clinical diagnostics, epidemiology, and environmental control of human pathogens.
Collapse
|
28
|
|