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Radde N, Mortensen GA, Bhat D, Shah S, Clements JJ, Leonard SP, McGuffie MJ, Mishler DM, Barrick JE. Measuring the burden of hundreds of BioBricks defines an evolutionary limit on constructability in synthetic biology. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.08.588465. [PMID: 38645188 PMCID: PMC11030366 DOI: 10.1101/2024.04.08.588465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/23/2024]
Abstract
Engineered DNA will slow the growth of a host cell if it redirects limiting resources or otherwise interferes with homeostasis. Populations of engineered cells can rapidly become dominated by "escape mutants" that evolve to alleviate this burden by inactivating the intended function. Synthetic biologists working with bacteria rely on genetic parts and devices encoded on plasmids, but the burden of different engineered DNA sequences is rarely characterized. We measured how 301 BioBricks on high-copy plasmids affected the growth rate of Escherichia coli . Of these, 59 (19.6%) negatively impacted growth. The burden imposed by engineered DNA is commonly associated with diverting ribosomes or other gene expression factors away from producing endogenous genes that are essential for cellular replication. In line with this expectation, BioBricks exhibiting burden were more likely to contain highly active constitutive promoters and strong ribosome binding sites. By monitoring how much each BioBrick reduced expression of a chromosomal GFP reporter, we found that the burden of most, but not all, BioBricks could be wholly explained by diversion of gene expression resources. Overall, no BioBricks reduced the growth rate of E. coli by >45%, which agreed with a population genetic model that predicts such plasmids should be "unclonable" because escape mutants will take over during growth of a bacterial colony or small laboratory culture from a transformed cell. We made this model available as an interactive web tool for synthetic biology education and added our burden measurements to the iGEM Registry descriptions of each BioBrick.
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Sun H, Li H, Zhang X, Liu Y, Chen H, Zheng L, Zhai Y, Zheng H. The honeybee gut resistome and its role in antibiotic resistance dissemination. Integr Zool 2023; 18:1014-1026. [PMID: 36892101 DOI: 10.1111/1749-4877.12714] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/10/2023]
Abstract
There is now general concern about widespread antibiotic resistance, and growing evidence indicates that gut microbiota is critical in providing antibiotic resistance. Honeybee is an important pollinator; the incidence of antibiotic resistance genes in honeybee gut causes potential risks to not only its own health but also to public and animal health, for its potential disseminator role, thus receiving more attention from the public. Recent analysis results reveal that the gut of honeybee serves as a reservoir of antibiotic resistance genes, probably due to antibiotics application history in beekeeping and horizontal gene transfer from the highly polluted environment. These antibiotic resistance genes accumulate in the honeybee gut and could be transferred to the pathogen, even having the potential to spread during pollination, tending, social interactions, etc. Newly acquired resistance traits may cause fitness reduction in bacteria whereas facilitating adaptive evolution as well. This review outlines the current knowledge about the resistome in honeybee gut and emphasizes its role in antibiotic resistance dissemination.
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Affiliation(s)
- Huihui Sun
- Institute of Plant Protection, Shandong Academy of Agricultural Sciences, Jinan, China
- Sanya Institute of China Agricultural University, Sanya, China
| | - Hu Li
- Department of Entomology, College of Plant Protection, China Agricultural University, Beijing, China
| | - Xue Zhang
- Department of Entomology, College of Plant Protection, China Agricultural University, Beijing, China
| | - Yan Liu
- Institute of Plant Protection, Shandong Academy of Agricultural Sciences, Jinan, China
- Key Laboratory of Natural Enemies Insects, Ministry of Agriculture and Rural Affairs, Jinan, China
- Shandong Provincial Engineering Technology Research Center on Biocontrol of Crops Diseases and Insect Pests, Jinan, China
| | - Hao Chen
- Institute of Plant Protection, Shandong Academy of Agricultural Sciences, Jinan, China
- Key Laboratory of Natural Enemies Insects, Ministry of Agriculture and Rural Affairs, Jinan, China
- Shandong Provincial Engineering Technology Research Center on Biocontrol of Crops Diseases and Insect Pests, Jinan, China
| | - Li Zheng
- Institute of Plant Protection, Shandong Academy of Agricultural Sciences, Jinan, China
- Key Laboratory of Natural Enemies Insects, Ministry of Agriculture and Rural Affairs, Jinan, China
- Shandong Provincial Engineering Technology Research Center on Biocontrol of Crops Diseases and Insect Pests, Jinan, China
| | - Yifan Zhai
- Institute of Plant Protection, Shandong Academy of Agricultural Sciences, Jinan, China
- Key Laboratory of Natural Enemies Insects, Ministry of Agriculture and Rural Affairs, Jinan, China
- Shandong Provincial Engineering Technology Research Center on Biocontrol of Crops Diseases and Insect Pests, Jinan, China
| | - Hao Zheng
- Institute of Plant Protection, Shandong Academy of Agricultural Sciences, Jinan, China
- Key Laboratory of Natural Enemies Insects, Ministry of Agriculture and Rural Affairs, Jinan, China
- Shandong Provincial Engineering Technology Research Center on Biocontrol of Crops Diseases and Insect Pests, Jinan, China
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Jia M, Li P, Zhang J, Chen Z, Gao L, Sun Y, Zhang X, Yan Y, Zhu G. Characteristics of Two mcr-1-Harboring IncHI2 Plasmids from Clinical Salmonella Isolates in Jiaxing City. Foodborne Pathog Dis 2023; 20:467-476. [PMID: 37699240 DOI: 10.1089/fpd.2023.0051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/14/2023] Open
Abstract
Salmonella is a primary cause of foodborne diseases, and the increasing prevalence of mcr-1-carrying plasmids, which confer colistin resistance to Salmonella, poses significant global health concerns. As the frequency of occurrence of the mcr-1 gene is increasing globally, we studied the prevalence of mcr-1 in clinical Salmonella isolates by analyzing 195 clinical strains isolated in 2020. Of the 195 Salmonella isolates, 41 isolates were resistant to colistin. We found mcr-1 in two strains (Salmonella Typhimurium ZJJX20006 and Salmonella Kentucky ZJJX20014), which we analyzed in detail via whole-genome sequencing and antibiotic susceptibility testing. Two strains displayed resistance to ampicillin, ampicillin-sulbactam, tetracycline, chloramphenicol, and cotrimoxazole, while ZJJX20006 displayed resistance to colistin and ZJJX20014 was sensitive. Genomic analysis revealed that these strains had plasmid-encoded mcr-1 in IncHI2 plasmids, which were not similar to the mcr-1-IncX4 identified in 2016. These two strains also harbored other drug resistance genes, including blaOXA-1 and blaCTX-M-14. Our findings may help clarify the molecular mechanisms of mcr-1 dissemination among Salmonella strains in Jiaxing City and offer insights into the evolution of mcr-1 in Salmonella.
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Affiliation(s)
- Miaomiao Jia
- Jiaxing Key Laboratory of Pathogenic Microbiology, Jiaxing Center for Disease Control and Prevention, Jiaxing, China
| | - Ping Li
- Jiaxing Key Laboratory of Pathogenic Microbiology, Jiaxing Center for Disease Control and Prevention, Jiaxing, China
| | - Junyan Zhang
- Institute of Microbiology, Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, China
| | - Zhongwen Chen
- Jiaxing Key Laboratory of Pathogenic Microbiology, Jiaxing Center for Disease Control and Prevention, Jiaxing, China
| | - Lei Gao
- Jiaxing Key Laboratory of Pathogenic Microbiology, Jiaxing Center for Disease Control and Prevention, Jiaxing, China
| | - Yangming Sun
- Jiaxing Key Laboratory of Pathogenic Microbiology, Jiaxing Center for Disease Control and Prevention, Jiaxing, China
| | - Xiaofei Zhang
- Jiaxing Key Laboratory of Pathogenic Microbiology, Jiaxing Center for Disease Control and Prevention, Jiaxing, China
| | - Yong Yan
- Jiaxing Key Laboratory of Pathogenic Microbiology, Jiaxing Center for Disease Control and Prevention, Jiaxing, China
| | - Guoying Zhu
- Jiaxing Key Laboratory of Pathogenic Microbiology, Jiaxing Center for Disease Control and Prevention, Jiaxing, China
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Abstract
Naturally occurring plasmids come in different sizes. The smallest are less than a kilobase of DNA, while the largest can be over three orders of magnitude larger. Historically, research has tended to focus on smaller plasmids that are usually easier to isolate, manipulate and sequence, but with improved genome assemblies made possible by long-read sequencing, there is increased appreciation that very large plasmids—known as megaplasmids—are widespread, diverse, complex, and often encode key traits in the biology of their host microorganisms. Why are megaplasmids so big? What other features come with large plasmid size that could affect bacterial ecology and evolution? Are megaplasmids 'just' big plasmids, or do they have distinct characteristics? In this perspective, we reflect on the distribution, diversity, biology, and gene content of megaplasmids, providing an overview to these large, yet often overlooked, mobile genetic elements. This article is part of the theme issue ‘The secret lives of microbial mobile genetic elements’.
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Affiliation(s)
- James P J Hall
- Department of Evolution, Ecology and Behaviour, Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK
| | - João Botelho
- Antibiotic Resistance Evolution Group, Max Planck Institute for Evolutionary Biology, Plön, Germany.,Department of Evolutionary Ecology and Genetics, Zoological Institute, Christian Albrechts University, Kiel, Germany
| | - Adrian Cazares
- EMBL's European Bioinformatics Institute (EMBL-EBI), Wellcome Genome Campus, Cambridge, UK.,Wellcome Sanger Institute, Wellcome Genome Campus, Cambridge, UK
| | - David A Baltrus
- School of Plant Sciences, University of Arizona, Tucson, AZ, USA
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Sugimoto R, Nishimura L, Nguyen PT, Ito J, Parrish NF, Mori H, Kurokawa K, Nakaoka H, Inoue I. Comprehensive discovery of CRISPR-targeted terminally redundant sequences in the human gut metagenome: Viruses, plasmids, and more. PLoS Comput Biol 2021; 17:e1009428. [PMID: 34673779 PMCID: PMC8530359 DOI: 10.1371/journal.pcbi.1009428] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 09/07/2021] [Indexed: 12/12/2022] Open
Abstract
Viruses are the most numerous biological entity, existing in all environments and infecting all cellular organisms. Compared with cellular life, the evolution and origin of viruses are poorly understood; viruses are enormously diverse, and most lack sequence similarity to cellular genes. To uncover viral sequences without relying on either reference viral sequences from databases or marker genes that characterize specific viral taxa, we developed an analysis pipeline for virus inference based on clustered regularly interspaced short palindromic repeats (CRISPR). CRISPR is a prokaryotic nucleic acid restriction system that stores the memory of previous exposure. Our protocol can infer CRISPR-targeted sequences, including viruses, plasmids, and previously uncharacterized elements, and predict their hosts using unassembled short-read metagenomic sequencing data. By analyzing human gut metagenomic data, we extracted 11,391 terminally redundant CRISPR-targeted sequences, which are likely complete circular genomes. The sequences included 2,154 tailed-phage genomes, together with 257 complete crAssphage genomes, 11 genomes larger than 200 kilobases, 766 genomes of Microviridae species, 56 genomes of Inoviridae species, and 95 previously uncharacterized circular small genomes that have no reliably predicted protein-coding gene. We predicted the host(s) of approximately 70% of the discovered genomes at the taxonomic level of phylum by linking protospacers to taxonomically assigned CRISPR direct repeats. These results demonstrate that our protocol is efficient for de novo inference of CRISPR-targeted sequences and their host prediction. The evolution and origins of viruses are long-standing questions in the field of biology. Viral genomes provide fundamental information to infer the evolution and origin of viruses. However, viruses are extraordinarily diverse, and there are no single genes shared across entire species. Several methods were developed to collect viral genomes from metagenome. To infer viral genomes from metagenome, previous approaches relied on reference viral genomes. We thought that such reference-based methods may not be sufficient to uncover diverse viral genomes; therefore, we developed a pipeline that utilizes CRISPR, a prokaryotic adaptive immunological memory. Using this pipeline, we discovered more than 10,000 positively complete CRISPR-targeted genomes from human gut metagenome datasets. A substantial portion of the discovered genomes encoded various types of capsid proteins, supporting the contention that these sequences are viral. Although the majority of these capsid-protein-coding sequences were previously characterized, we notably discovered Inoviridae genomes that were previously difficult to infer as being viral. Furthermore, some of the remaining unclassified sequences without a detectable capsid-protein-encoding gene had a notably low protein-coding ratio. Overall, our pipeline successfully discovered viruses and previously uncharacterized presumably mobile genetic elements targeted by CRISPR.
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Affiliation(s)
- Ryota Sugimoto
- Human Genetics Laboratory, National Institute of Genetics, Research Organization of Information and Systems, Mishima, Shizuoka, Japan
| | - Luca Nishimura
- Human Genetics Laboratory, National Institute of Genetics, Research Organization of Information and Systems, Mishima, Shizuoka, Japan
- The Graduate University for Advanced Studies, SOKENDAI, Mishima, Shizuoka, Japan
| | - Phuong Thanh Nguyen
- Human Genetics Laboratory, National Institute of Genetics, Research Organization of Information and Systems, Mishima, Shizuoka, Japan
- The Graduate University for Advanced Studies, SOKENDAI, Mishima, Shizuoka, Japan
| | - Jumpei Ito
- Division of Systems Virology, Department of Infectious Disease Control, International Research Center for Infectious Diseases, Institute of Medical Science, The University of Tokyo, Minato-ku, Tokyo, Japan
| | - Nicholas F. Parrish
- Genome Immunobiology RIKEN Hakubi Research Team, Center for Integrative Medical Sciences, RIKEN, Tsurumi-ku, Yokohama, Kanagawa, Japan
| | - Hiroshi Mori
- Genome Diversity Laboratory, National Institute of Genetics, Research Organization of Information and Systems, Mishima, Shizuoka, Japan
| | - Ken Kurokawa
- Genome Evolution Laboratory, National Institute of Genetics, Research Organization of Information and Systems, Mishima, Shizuoka, Japan
| | - Hirofumi Nakaoka
- Department of Cancer Genome Research, Sasaki Institute, Chiyoda-ku, Tokyo, Japan
| | - Ituro Inoue
- Human Genetics Laboratory, National Institute of Genetics, Research Organization of Information and Systems, Mishima, Shizuoka, Japan
- * E-mail:
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Shen C, Ma F, Deng S, Zhong LL, El-Sayed Ahmed MAEG, Zhang G, Yan B, Dai M, Yang F, Xia Y, Tian GB. Prevalence, genomic characteristics, and transmission dynamics of mcr-1-positive Salmonella enterica Typhimurium from patients with infectious diarrhea. Int J Med Microbiol 2021; 311:151501. [PMID: 33866091 DOI: 10.1016/j.ijmm.2021.151501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 03/25/2021] [Accepted: 03/28/2021] [Indexed: 10/21/2022] Open
Abstract
BACKGROUND Previous studies reported the prevalence of mcr-1 among clinical infected Salmonella isolates in China. However, the transmission dynamics of mcr-1 in different ecological niches were not well investigated. Our objective is to exhibit the transmission dynamics of mcr-1 in Salmonella. METHODS 598 Salmonella isolates were recovered from ten hospitals; besides 936 pig faces and 167 pork samples were collected from January 2015 to December 2017 in Guangzhou, China. PCR and sequencing were used to identify mcr-1-positive Salmonella. Antimicrobial susceptibility testing was performed with 16 antimicrobials. Conjugation, S1-PFGE, and Southern blot were used to determine the transferability and location of mcr-1. Whole-genome sequencing was used to investigate pangenome, phylogeny, plasmid, and transposon. RESULTS Eleven mcr-1-positive Salmonella isolates were identified from patients with infectious diarrhea. Five pig fecal samples and three pork samples contained mcr-1-positive Salmonella isolates. All isolates were multi-drug resistant. The mcr-1 genes were located on ∼210-250 kb IncHI2-pST3 plasmids, and 12 mcr-1 genes were transferable. All isolates were assigned to ST34 or its genetically closed STs. The distribution of the core-genome network was significantly correlated with source distributions. The accessory genes-based network demonstrated that the diverse clonal complexes could share highly similar accessory genomes. CONCLUSIONS The prevalence of mcr-1-positive Salmonella among different sources was low. Clonal transmission could not be the main reason for the expansion of mcr-1-positive Salmonella, but be attributed to the horizontal transfer of IncHI2-pST3 plasmid. Continuous surveillance on Salmonella should be performed to investigate the response of colistin banning in food-producing animals by mcr-1-positive Salmonella populations.
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Affiliation(s)
- Cong Shen
- Department of Clinical Laboratory Medicine, Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, China; Department of Microbiology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China; Key Laboratory of Tropical Diseases Control (Sun Yat-sen University), Ministry of Education, Guangzhou, 510080, China
| | - Furong Ma
- Department of Clinical Laboratory Medicine, Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Suiyan Deng
- Department of Clinical Laboratory Medicine, Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Lan-Lan Zhong
- Department of Microbiology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China; Key Laboratory of Tropical Diseases Control (Sun Yat-sen University), Ministry of Education, Guangzhou, 510080, China
| | - Mohamed Abd El-Gawad El-Sayed Ahmed
- Department of Microbiology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China; Key Laboratory of Tropical Diseases Control (Sun Yat-sen University), Ministry of Education, Guangzhou, 510080, China; Department of Microbiology and Immunology, Faculty of Pharmaceutical Sciences and Drug Manufacturing, Misr University for Science and Technology (MUST), Cairo, 6th of October City, Egypt
| | - Guili Zhang
- Department of Microbiology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China; Key Laboratory of Tropical Diseases Control (Sun Yat-sen University), Ministry of Education, Guangzhou, 510080, China
| | - Bin Yan
- Department of Neonatal Surgery, Guangzhou Women and Children's Medical Center, Guangzhou, China
| | - Min Dai
- School of Laboratory Medicine, Chengdu Medical College, Chengdu, 610500, China
| | - Fan Yang
- Basic Medical College, Xinxiang Medical University, Xinxiang, 453003, China
| | - Yong Xia
- Department of Clinical Laboratory Medicine, Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, China.
| | - Guo-Bao Tian
- Department of Microbiology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China; Key Laboratory of Tropical Diseases Control (Sun Yat-sen University), Ministry of Education, Guangzhou, 510080, China; School of Medicine, Xizang Minzu University, Xianyang, Shaanxi 712082, China.
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7
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Johnson TJ. Role of Plasmids in the Ecology and Evolution of "High-Risk" Extraintestinal Pathogenic Escherichia coli Clones. EcoSal Plus 2021; 9:eESP-0013-2020. [PMID: 33634776 PMCID: PMC11163845 DOI: 10.1128/ecosalplus.esp-0013-2020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 01/12/2021] [Indexed: 11/20/2022]
Abstract
Bacterial plasmids have been linked to virulence in Escherichia coli and Salmonella since their initial discovery. Though the plasmid repertoire of these bacterial species is extremely diverse, virulence-associated attributes tend to be limited to a small subset of plasmid types. This is particularly true for extraintestinal pathogenic E. coli, or ExPEC, where a handful of plasmids have been recognized to confer virulence- and fitness-associated traits. The purpose of this review is to highlight the biological and genomic attributes of ExPEC virulence-associated plasmids, with an emphasis on high-risk dominant ExPEC clones. Two specific plasmid types are highlighted to illustrate the independently evolved commonalities of these clones relative to plasmid content. Furthermore, the dissemination of these plasmids within and between bacterial species is examined. These examples demonstrate the evolution of high-risk clones toward common goals, and they show that rare transfer events can shape the ecological landscape of dominant clones within a pathotype.
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Affiliation(s)
- Timothy J. Johnson
- Department of Veterinary and Biomedical Sciences, University of Minnesota, Saint Paul, MN 55108
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Garoña A, Dagan T. Darwinian individuality of extrachromosomal genetic elements calls for population genetics tinkering. ENVIRONMENTAL MICROBIOLOGY REPORTS 2021; 13:22-26. [PMID: 33034073 DOI: 10.1111/1758-2229.12894] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 10/06/2020] [Indexed: 06/11/2023]
Abstract
Plasmids are extrachromosomal genetic elements commonly found in prokaryotic (and sometime eukaryotic) cells. Small plasmids are often considered cryptic and their effect on the host is elusive, while large plasmids may encode functions that are essential for the host lifestyle and attain a secondary chromosome status. Plasmids are thus an important source of raw material for microbial genome evolution outside the mainstream of bacterial chromosomes. The discovery of plasmid-mediated antibiotic resistance led to extensive research on the contribution of plasmids to the environmental dimensions of antibiotic resistance and the evolution of plasmid-host interactions following the acquisition of plasmids encoding for antibiotic resistance. Recent experimental studies revealed the importance of intracellular plasmid diversity for plasmid-host interactions. Here we describe the evolutionary forces at play during plasmid evolution in a top-down approach: this includes the effect of processes at the level of the host population and the consideration of plasmids as Darwinian individuals within the host cell.
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Affiliation(s)
- Ana Garoña
- Institute of General Microbiology, Kiel University, Kiel, Germany
| | - Tal Dagan
- Institute of General Microbiology, Kiel University, Kiel, Germany
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Rugbjerg P, Olsson L. The future of self-selecting and stable fermentations. J Ind Microbiol Biotechnol 2020; 47:993-1004. [PMID: 33136197 PMCID: PMC7695646 DOI: 10.1007/s10295-020-02325-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 10/17/2020] [Indexed: 02/08/2023]
Abstract
Unfavorable cell heterogeneity is a frequent risk during bioprocess scale-up and characterized by rising frequencies of low-producing cells. Low-producing cells emerge by both non-genetic and genetic variation and will enrich due to their higher specific growth rate during the extended number of cell divisions of large-scale bioproduction. Here, we discuss recent strategies for synthetic stabilization of fermentation populations and argue for their application to make cell factory designs that better suit industrial needs. Genotype-directed strategies leverage DNA-sequencing data to inform strain design. Self-selecting phenotype-directed strategies couple high production with cell proliferation, either by redirected metabolic pathways or synthetic product biosensing to enrich for high-performing cell variants. Evaluating production stability early in new cell factory projects will guide heterogeneity-reducing design choices. As good initial metrics, we propose production half-life from standardized serial-passage stability screens and production load, quantified as production-associated percent-wise growth rate reduction. Incorporating more stable genetic designs will greatly increase scalability of future cell factories through sustaining a high-production phenotype and enabling stable long-term production.
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Affiliation(s)
- Peter Rugbjerg
- Enduro Genetics ApS, Copenhagen, Denmark. .,Department of Biology and Biological Engineering, Industrial Biotechnology, Chalmers University of Technology, Gothenburg, Sweden.
| | - Lisbeth Olsson
- Department of Biology and Biological Engineering, Industrial Biotechnology, Chalmers University of Technology, Gothenburg, Sweden
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10
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Meir M, Harel N, Miller D, Gelbart M, Eldar A, Gophna U, Stern A. Competition between social cheater viruses is driven by mechanistically different cheating strategies. SCIENCE ADVANCES 2020; 6:6/34/eabb7990. [PMID: 32937370 PMCID: PMC7442481 DOI: 10.1126/sciadv.abb7990] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Accepted: 07/09/2020] [Indexed: 05/09/2023]
Abstract
Cheater viruses, also known as defective interfering viruses, cannot replicate on their own yet replicate faster than the wild type upon coinfection. While there is growing interest in using cheaters as antiviral therapeutics, the mechanisms underlying cheating have been rarely explored. During experimental evolution of MS2 phage, we observed the parallel emergence of two independent cheater mutants. The first, a point deletion mutant, lacked polymerase activity but was advantageous in viral packaging. The second synonymous mutant cheater displayed a completely different cheating mechanism, involving an altered RNA structure. Continued evolution revealed the demise of the deletion cheater and rise of the synonymous cheater. A mathematical model inferred that while a single cheater is expected to reach an equilibrium with the wild type, cheater demise arises from antagonistic interactions between coinfecting cheaters. These findings highlight layers of parasitism: viruses parasitizing cells, cheaters parasitizing intact viruses, and cheaters may parasitize other cheaters.
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Affiliation(s)
- Moran Meir
- School of Molecular Cell Biology and Biotechnology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Israel
| | - Noam Harel
- School of Molecular Cell Biology and Biotechnology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Israel
| | - Danielle Miller
- School of Molecular Cell Biology and Biotechnology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Israel
| | - Maoz Gelbart
- School of Molecular Cell Biology and Biotechnology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Israel
| | - Avigdor Eldar
- School of Molecular Cell Biology and Biotechnology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Israel
| | - Uri Gophna
- School of Molecular Cell Biology and Biotechnology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Israel.
| | - Adi Stern
- School of Molecular Cell Biology and Biotechnology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Israel.
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Deciphering the Structural Diversity and Classification of the Mobile Tigecycline Resistance Gene tet(X)-Bearing Plasmidome among Bacteria. mSystems 2020; 5:5/2/e00134-20. [PMID: 32345737 PMCID: PMC7190383 DOI: 10.1128/msystems.00134-20] [Citation(s) in RCA: 83] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Tigecycline is an expanded-spectrum tetracycline used as a last-resort antimicrobial for treating infections caused by superbugs such as carbapenemase-producing or colistin-resistant pathogens. Emergence of the plasmid-mediated mobile tigecycline resistance gene tet(X4) created a great public health concern. However, the diversity of tet(X4)-bearing plasmids and bacteria remains largely uninvestigated. To cover this knowledge gap, we comprehensively identified and characterized the tet(X)-bearing plasmidome in different sources using advanced sequencing technologies for the first time. The huge diversity of tet(X4)-bearing mobile elements demonstrates the high level of transmissibility of the tet(X4) gene among bacteria. It is crucial to enhance stringent surveillance of tet(X) genes in animal and human pathogens globally. The emergence of novel plasmid-mediated resistance genes constitutes a great public concern. Recently, mobile tet(X) variants were reported in diverse pathogens from different sources. However, the diversity of tet(X)-bearing plasmids remains largely unknown. In this study, the phenotypes and genotypes of all the tet(X)-positive tigecycline-resistant strains isolated from a slaughterhouse in China were characterized by antimicrobial susceptibility testing, conjugation, pulsed-field gel electrophoresis with S1 nuclease (S1-PFGE), and PCR. The diversity and polymorphism of tet(X)-harboring strains and plasmidomes were investigated by whole-genome sequencing (WGS) and single-plasmid-molecule analysis. Seventy-four tet(X4)-harboring Escherichia coli strains and one tet(X6)-bearing Providencia rettgeri strain were identified. The tet(X4)-bearing elements in 27 strains could be transferred to the recipient strain via plasmids. All tet(X4)-bearing plasmids isolated in this study and 15 tet(X4)-bearing plasmids reported online were analyzed. tet(X4)-bearing plasmids ranged from 9 to 294 kb and were categorized as ColE2-like, IncQ, IncX1, IncA/C2, IncFII, IncFIB, and hybrid plasmids with different replicons. The core tet(X4)-bearing genetic contexts were divided into four major groups: ISCR2-tet(X4)-abh, △ISCR2-abh-tet(X4)-ISCR2, ISCR2-abh-tet(X4)-ISCR2-virD2-floR, and abh-tet(X4)-ISCR2-yheS-cat-zitR-ISCR2-virD2-floR. Tandem repeats of tet(X4) were universally mediated by ISCR2. Different tet(X)-bearing strains existed in the same microbiota. Reorganization of tet(X4)-bearing multidrug resistance plasmids was found to be mediated by IS26 and other homologous regions. Finally, single-plasmid-molecule analysis captured the heterogenous state of tet(X4)-bearing plasmids. These findings significantly expand our knowledge of the tet(X)-bearing plasmidome among microbiotas, which establishes a baseline for investigating the structure and diversity of human, animal, and environmental tigecycline resistomes. Characterization of tet(X) genes among different microbiotas should be performed systematically to understand the evolution and ecology. IMPORTANCE Tigecycline is an expanded-spectrum tetracycline used as a last-resort antimicrobial for treating infections caused by superbugs such as carbapenemase-producing or colistin-resistant pathogens. Emergence of the plasmid-mediated mobile tigecycline resistance gene tet(X4) created a great public health concern. However, the diversity of tet(X4)-bearing plasmids and bacteria remains largely uninvestigated. To cover this knowledge gap, we comprehensively identified and characterized the tet(X)-bearing plasmidome in different sources using advanced sequencing technologies for the first time. The huge diversity of tet(X4)-bearing mobile elements demonstrates the high level of transmissibility of the tet(X4) gene among bacteria. It is crucial to enhance stringent surveillance of tet(X) genes in animal and human pathogens globally.
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