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Mishra N, Srivastava R. Bacterial worth in genotoxicity assessment studies. J Microbiol Methods 2023; 215:106860. [PMID: 38008307 DOI: 10.1016/j.mimet.2023.106860] [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: 10/16/2023] [Revised: 11/18/2023] [Accepted: 11/19/2023] [Indexed: 11/28/2023]
Abstract
Bacterial-based genotoxicity test systems play a significant role in the detection and evaluation of genotoxicity in vitro and have gained importance due to attributes like wide applicability, speed, high sensitivity, good reproducibility, and simplicity. The Salmonella microsomal mutagenicity assay was created by Ames and colleagues at the beginning of the 1970s, and it was based on the fundamental notion that in auxotrophic bacterial strains with inhibited growth, a mutant gene would revert to its original state on exposure to genotoxicants. This is the most successful and widely used in vitro genotoxicity test. Later, a number of additional test systems that incorporated DNA repair mechanisms including the bacterial SOS response were created. Genetic engineering has further provided significant advancement in these test systems with the development of highly sophisticated bacterial tester strains with significantly increased sensitivity to evaluate the chemical nature of hazardous substances and pollutants. These bacterial bioassays render an opportunity to detect the defined effects of compounds at the molecular level. In this review, all the aspects related to the bacterial system in genotoxicity assessment have been summarized and their role is elaborated concerning real-time requirements and future perspectives.
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Affiliation(s)
- Nidhi Mishra
- Department of Zoology, University of Lucknow, Lucknow, U.P. 226007, India.
| | - Rashmi Srivastava
- Department of Zoology, Babasaheb Bhimrao Ambedkar University, Lucknow, U.P. 226025, India
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2
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Ping L, Zhuoya L, Pei J, Jingchao C, Yi L, Guosheng L, Hailei W. Editing of a Specific Strain of Escherichia coli in the Mouse Gut Using Native Phages. Microbiol Spectr 2022; 10:e0180422. [PMID: 36301104 PMCID: PMC9770003 DOI: 10.1128/spectrum.01804-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Accepted: 09/20/2022] [Indexed: 01/05/2023] Open
Abstract
There is a lack of methodological investigation of the in situ functions of bacterial species in microecosystems. Here, we used native phages as a microbial editing tool for eliminating Escherichia coli strain MG1655 labeled with green fluorescent protein (GFP) in the mouse gut. The virulent phages (W1 and W3) possessed host specificity at both the genus and species levels, resulting in an 8.8-log10 difference in the titer of viable bacteria after 12 h of phage treatment compared with that in the phage-free control in an in vitro test. In vivo, they reduced strain MG1655 colonizing the mouse gut at concentrations of 106 to 108 CFU g-1 to a 102 CFU g-1 level, which is almost undetectable by the plate colony-counting method. Moreover, the impact of phage treatment on the microbial community structure of the mouse gut was not significant (P > 0.05), indicating that native phages can effectively edit a target bacterium, with limited perturbation of microbial diversity and relative abundance. Therefore, we developed an engineering technique for investigation of the functions of a specific bacterium by depleting its abundance in microecosystems. IMPORTANCE This report describes a gut engineering technique for investigation of the functions of a specific bacterium. Native phages with host specificity can knock down the corresponding E. coli strain in the mouse gut with limited perturbation of microbial diversity and relative abundance, indicating that they, as a microbial editing tool, can effectively edit the abundance of a target bacterium. Such an approach is undoubtedly of interest in the context of lack of knowledge of how to methodologically study the in situ function of a specific species in a complex microecosystem.
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Affiliation(s)
- Li Ping
- College of Life Sciences, Henan Normal University, Xinxiang, China
| | - Li Zhuoya
- College of Life Sciences, Henan Normal University, Xinxiang, China
| | - Jia Pei
- College of Life Sciences, Henan Normal University, Xinxiang, China
| | - Chen Jingchao
- College of Life Sciences, Henan Normal University, Xinxiang, China
| | - Li Yi
- College of Life Sciences, Henan Normal University, Xinxiang, China
| | - Liu Guosheng
- College of Life Sciences, Henan Normal University, Xinxiang, China
| | - Wang Hailei
- College of Life Sciences, Henan Normal University, Xinxiang, China
- Advanced Environmental Biotechnology Center, Nanyang Technological University, Singapore, Singapore
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Standley M, Blay V, Beleva Guthrie V, Kim J, Lyman A, Moya A, Karchin R, Camps M. Experimental and In Silico Analysis of TEM β-Lactamase Adaptive Evolution. ACS Infect Dis 2022; 8:2451-2463. [PMID: 36377311 PMCID: PMC9745794 DOI: 10.1021/acsinfecdis.2c00216] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Multiple mutations often have non-additive (epistatic) phenotypic effects. Epistasis is of fundamental biological relevance but is not well understood mechanistically. Adaptive evolution, i.e., the evolution of new biochemical activities, is rich in epistatic interactions. To better understand the principles underlying epistasis during genetic adaptation, we studied the evolution of TEM-1 β-lactamase variants exhibiting cefotaxime resistance. We report the collection of a library of 487 observed evolutionary trajectories for TEM-1 and determine the epistasis status based on cefotaxime resistance phenotype for 206 combinations of 2-3 TEM-1 mutations involving 17 positions under adaptive selective pressure. Gain-of-function (GOF) mutations are gatekeepers for adaptation. To see if GOF phenotypes can be inferred based solely on sequence data, we calculated the enrichment of GOF mutations in the different categories of epistatic pairs. Our results suggest that this is possible because GOF mutations are particularly enriched in sign and reciprocal sign epistasis, which leave a major imprint on the sequence space accessible to evolution. We also used FoldX to explore the relationship between thermodynamic stability and epistasis. We found that mutations in observed evolutionary trajectories tend to destabilize the folded structure of the protein, albeit their cumulative effects are consistently below the protein's free energy of folding. The destabilizing effect is stronger for epistatic pairs, suggesting that modest or local alterations in folding stability can modulate catalysis. Finally, we report a significant relationship between epistasis and the degree to which two protein positions are structurally and dynamically coupled, even in the absence of ligand.
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Affiliation(s)
- Melissa Standley
- Department
of Microbiology and Environmental Toxicology, University of California, Santa
Cruz, California95064, United States
| | - Vincent Blay
- Department
of Microbiology and Environmental Toxicology, University of California, Santa
Cruz, California95064, United States,Institute
for Integrative Systems Biology (I2Sysbio), Universitat de València and Spanish Research Council (CSIC), 46980Valencia, Spain,
| | - Violeta Beleva Guthrie
- Department
of Biomedical Engineering and Institute for Computational Medicine, The Johns Hopkins University, Baltimore, Maryland21218, United States
| | - Jay Kim
- Department
of Microbiology and Environmental Toxicology, University of California, Santa
Cruz, California95064, United States
| | - Audrey Lyman
- Department
of Microbiology and Environmental Toxicology, University of California, Santa
Cruz, California95064, United States
| | - Andrés Moya
- Institute
for Integrative Systems Biology (I2Sysbio), Universitat de València and Spanish Research Council (CSIC), 46980Valencia, Spain,Foundation
for the Promotion of Sanitary and Biomedical Research of Valencia
Region (FISABIO), 46021Valencia, Spain,CIBER
in Epidemiology and Public Health (CIBEResp), 28029Madrid, Spain
| | - Rachel Karchin
- Department
of Biomedical Engineering and Institute for Computational Medicine, The Johns Hopkins University, Baltimore, Maryland21218, United States
| | - Manel Camps
- Department
of Microbiology and Environmental Toxicology, University of California, Santa
Cruz, California95064, United States,
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Ranjbar M, Behrouz B, Norouzi F, Mousavi Gargari SL. Anti-PcrV IgY antibodies protect against Pseudomonas aeruginosa infection in both acute pneumonia and burn wound models. Mol Immunol 2019; 116:98-105. [PMID: 31634816 DOI: 10.1016/j.molimm.2019.10.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Revised: 10/04/2019] [Accepted: 10/07/2019] [Indexed: 12/11/2022]
Abstract
Pseudomonas aeruginosa is a common nosocomial pathogen in burn patients, and rapidly acquires antibiotic resistance; thus, developing an effective therapeutic approach is the most promising strategy for combating infection. Type III secretion system (T3SS) translocates bacterial toxins into the cytosol of the targeted eukaryotic cells, which plays important roles in the virulence of P. aeruginosa infections in both acute pneumonia and burn wound models. The PcrV protein, a T3SS translocating protein, is required for T3SS function and is a well-validated target in animal models of immunoprophylactic strategies targeting P. aeruginosa. In the present study, we evaluated the protective efficacy of chicken egg yolk antibodies (IgY) raised against recombinant PcrV (r-PcrV) in both acute pneumonia and burn wound models. R-PcrV protein was generated by expressing the pcrV gene (cloned in pET-28a vector) in E. coli BL-21. Anti-PcrV IgY was obtained by immunization of hen. Anti-PcrV IgY induced greater protection in P. aeruginosamurine acute pneumonia and burn wound models than control IgY (C-IgY) and PBS groups. Anti-PcrV IgY improved opsonophagocytic killing and inhibition of bacterial invasion of host cells. Taken together, our data provide evidence that anti-PcrV IgY can be a promising therapeutic candidate for combating P. aeruginosa infections.
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Affiliation(s)
- Mahya Ranjbar
- Department of Microbiology, Shahed University, Faculty of Medical Sciences, Tehran, Iran; Department of Biology, Faculty of Basic Science, Shahed University, Tehran, Iran
| | - Bahador Behrouz
- Department of Biology, Faculty of Basic Science, Shahed University, Tehran, Iran
| | - Fatemeh Norouzi
- Department of Biology, Faculty of Basic Science, Shahed University, Tehran, Iran
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Hashemi FB, Behrouz B, Irajian G, Laghaei P, Korpi F, Fatemi MJ. A trivalent vaccine consisting of "flagellin A+B and pilin" protects against Pseudomonas aeruginosa infection in a murine burn model. Microb Pathog 2019; 138:103697. [PMID: 31465785 DOI: 10.1016/j.micpath.2019.103697] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Revised: 02/22/2019] [Accepted: 08/26/2019] [Indexed: 10/26/2022]
Abstract
Pseudomonas aeruginosa is a common nosocomial pathogen in burn patients, and rapidly achieves antibiotic resistance, and thus, developing an effective vaccine is critically important for combating P. aeruginosa infection. Flagella and pili play important roles in colonization of P. aeruginosa at the burn wound site and its subsequent dissemination to deeper tissue and organs. In the present study, we evaluated protective efficacy of a trivalent vaccine containing flagellins A and B (FlaA + FlaB) + pilin (PilA) in a murine burn model of infection. "FlaA + FlaB + PilA" induced greater protection in P. aeruginosa murine burn model than the single components alone, and it showed broad immune protection against P. aeruginosa strains. Immunization with "FlaA + FlaB + PilA" induced strong opsonophagocytic antibodies and resulted in reduced bacterial loads, systemic IL-12/IL-10 cytokine expression, and increased survival after challenge with three times lethal dose fifty (LD50) of P. eruginosa strains. Moreover, the protective efficacy of "FlaA + FlaB + PilA" vaccination was largely attributed to specific antibodies. Taken together, these data further confirm that the protective effects of "FlaA + FlaB + PilA" vaccine significantly enhance efficacy compared with antibodies against either mono or divalent antigen, and that the former broadens the coverage against P. eruginosa strains that express two of the three antigens.
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Affiliation(s)
- Farhad B Hashemi
- Department of Microbiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Bahador Behrouz
- Department of Microbiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran; Burn Research Center, Hazrat Fatima Hospital, Iran University of Medical Sciences, Tehran, Iran.
| | - Gholamreza Irajian
- Department of Microbiology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Parisa Laghaei
- Department of Microbiology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Fatemeh Korpi
- Department of Microbiology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Mohammad Javad Fatemi
- Burn Research Center, Hazrat Fatima Hospital, Iran University of Medical Sciences, Tehran, Iran.
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Standley MS, Million-Weaver S, Alexander DL, Hu S, Camps M. Genetic control of ColE1 plasmid stability that is independent of plasmid copy number regulation. Curr Genet 2018; 65:179-192. [PMID: 29909438 DOI: 10.1007/s00294-018-0858-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Revised: 06/08/2018] [Accepted: 06/12/2018] [Indexed: 02/07/2023]
Abstract
ColE1-like plasmid vectors are widely used for expression of recombinant genes in E. coli. For these vectors, segregation of individual plasmids into daughter cells during cell division appears to be random, making them susceptible to loss over time when no mechanisms ensuring their maintenance are present. Here we use the plasmid pGFPuv in a recA relA strain as a sensitized model to study factors affecting plasmid stability in the context of recombinant gene expression. We find that in this model, plasmid stability can be restored by two types of genetic modifications to the plasmid origin of replication (ori) sequence: point mutations and a novel 269 nt duplication at the 5' end of the plasmid ori, which we named DAS (duplicated anti-sense) ori. Combinations of these modifications produce a range of copy numbers and of levels of recombinant expression. In direct contradiction with the classic random distribution model, we find no correlation between increased plasmid copy number and increased plasmid stability. Increased stability cannot be explained by reduced levels of recombinant gene expression either. Our observations would be more compatible with a hybrid clustered and free-distribution model, which has been recently proposed based on detection of individual plasmids in vivo using super-resolution fluorescence microscopy. This work suggests a role for the plasmid ori in the control of segregation of ColE1 plasmids that is distinct from replication initiation, opening the door for the genetic regulation of plasmid stability as a strategy aimed at enhancing large-scale recombinant gene expression or bioremediation.
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Affiliation(s)
- Melissa S Standley
- Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, Santa Cruz, CA, 95064, USA
| | - Samuel Million-Weaver
- Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, Santa Cruz, CA, 95064, USA
- College of Engineering, University of Wisconsin-Madison, Madison, 53706, USA
| | - David L Alexander
- Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, Santa Cruz, CA, 95064, USA
- Department of Biomolecular Engineering, UCSC, Santa Cruz, USA
| | - Shuai Hu
- Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, Santa Cruz, CA, 95064, USA
| | - Manel Camps
- Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, Santa Cruz, CA, 95064, USA.
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