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Patel RR, Arun PP, Singh SK, Singh M. Mycobacterial biofilms: Understanding the genetic factors playing significant role in pathogenesis, resistance and diagnosis. Life Sci 2024; 351:122778. [PMID: 38879157 DOI: 10.1016/j.lfs.2024.122778] [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: 12/27/2023] [Revised: 05/25/2024] [Accepted: 06/04/2024] [Indexed: 07/03/2024]
Abstract
Even though the genus Mycobacterium is a diverse group consisting of a majority of environmental bacteria known as non-tuberculous mycobacteria (NTM), it also contains some of the deadliest pathogens (Mycobacterium tuberculosis) in history associated with chronic disease called tuberculosis (TB). Formation of biofilm is one of the unique strategies employed by mycobacteria to enhance their ability to survive in hostile conditions. Biofilm formation by Mycobacterium species is an emerging area of research with significant implications for understanding its pathogenesis and treatment of related infections, specifically TB. This review provides an overview of the biofilm-forming abilities of different species of Mycobacterium and the genetic factors influencing biofilm formation with a detailed focus on M. tuberculosis. Biofilm-mediated resistance is a significant challenge as it can limit antibiotic penetration and promote the survival of dormant mycobacterial cells. Key genetic factors promoting biofilm formation have been explored such as the mmpL genes involved in lipid transport and cell wall integrity as well as the groEL gene essential for mature biofilm formation. Additionally, biofilm-mediated antibiotic resistance and pathogenesis highlighting the specific niches, sites of infection along with the possible mechanisms of biofilm dissemination have been discussed. Furthermore, drug targets within mycobacterial biofilm and their role as potential biomarkers in the development of rapid diagnostic tools have been highlighted. The review summarises the current understanding of the complex nature of Mycobacterium biofilm and its clinical implications, paving the way for advancements in the field of disease diagnosis, management and treatment against its multi-drug resistant species.
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Affiliation(s)
- Ritu Raj Patel
- Department of Medicinal Chemistry, Faculty of Ayurveda, Institute of Medical Sciences, Banaras Hindu University, Varanasi 221005, India
| | - Pandey Priya Arun
- Department of Medicinal Chemistry, Faculty of Ayurveda, Institute of Medical Sciences, Banaras Hindu University, Varanasi 221005, India
| | - Sudhir Kumar Singh
- Department of Microbiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi 221005, India
| | - Meenakshi Singh
- Department of Medicinal Chemistry, Faculty of Ayurveda, Institute of Medical Sciences, Banaras Hindu University, Varanasi 221005, India.
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Sodani M, Misra CS, Nigam G, Fatima Z, Kulkarni S, Rath D. MSMEG_0311 is a conserved essential polar protein involved in mycobacterium cell wall metabolism. Int J Biol Macromol 2024; 260:129583. [PMID: 38242409 DOI: 10.1016/j.ijbiomac.2024.129583] [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: 11/23/2023] [Revised: 01/16/2024] [Accepted: 01/16/2024] [Indexed: 01/21/2024]
Abstract
Cell wall synthesis and cell division are two closely linked pathways in a bacterial cell which distinctly influence the growth and survival of a bacterium. This requires an appreciable coordination between the two processes, more so, in case of mycobacteria with an intricate multi-layered cell wall structure. In this study, we investigated a conserved gene cluster using CRISPR-Cas12 based gene silencing technology to show that knockdown of most of the genes in this cluster leads to growth defects. Investigating conserved genes is important as they likely perform vital cellular functions and the functional insights on such genes can be extended to other mycobacterial species. We characterised one of the genes in the locus, MSMEG_0311. The repression of this gene not only imparts severe growth defect but also changes colony morphology. We demonstrate that the protein preferentially localises to the polar region and investigate its influence on the polar growth of the bacillus. A combination of permeability and drug susceptibility assay strongly suggests a cell wall associated function of this gene which is also corroborated by transcriptomic analysis of the knockdown where a number of cell wall associated genes, particularly iniA and sigF regulon get altered. Considering the gene is highly conserved across mycobacterial species and appears to be essential for growth, it may serve as a potential drug target.
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Affiliation(s)
- Megha Sodani
- Radiation Medicine Centre, Medical Group, Bhabha Atomic Research Centre, Mumbai 400085, Maharashtra, India; Homi Bhabha National Institute, Training School Complex, Anushaktinagar, Mumbai 400094, Maharashtra, India
| | - Chitra S Misra
- Applied Genomics Section, Bio-Science Group, Bhabha Atomic Research Centre, Mumbai 400085, Maharashtra, India
| | - Gaurav Nigam
- Amity Institute of Biotechnology, Amity University Haryana, Gurugram, India
| | - Zeeshan Fatima
- Amity Institute of Biotechnology, Amity University Haryana, Gurugram, India; Department of Laboratory Medicine, Faculty of Applied Medical Sciences, University of Bisha, Bisha, Saudi Arabia
| | - Savita Kulkarni
- Radiation Medicine Centre, Medical Group, Bhabha Atomic Research Centre, Mumbai 400085, Maharashtra, India; Homi Bhabha National Institute, Training School Complex, Anushaktinagar, Mumbai 400094, Maharashtra, India.
| | - Devashish Rath
- Homi Bhabha National Institute, Training School Complex, Anushaktinagar, Mumbai 400094, Maharashtra, India; Applied Genomics Section, Bio-Science Group, Bhabha Atomic Research Centre, Mumbai 400085, Maharashtra, India.
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Born SEM, Reichlen MJ, Bartek IL, Benoit JB, Frank DN, Voskuil MI. Population heterogeneity in Mycobacterium smegmatis and Mycobacterium abscessus. MICROBIOLOGY (READING, ENGLAND) 2023; 169:001402. [PMID: 37862100 PMCID: PMC10634367 DOI: 10.1099/mic.0.001402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Accepted: 10/06/2023] [Indexed: 10/21/2023]
Abstract
Bacteria use population heterogeneity, the presence of more than one phenotypic variant in a clonal population, to endure diverse environmental challenges - a 'bet-hedging' strategy. Phenotypic variants have been described in many bacteria, but the phenomenon is not well-understood in mycobacteria, including the environmental factors that influence heterogeneity. Here, we describe three reproducible morphological variants in M. smegmatis - smooth, rough, and an intermediate morphotype that predominated under typical laboratory conditions. M. abscessus has two recognized morphotypes, smooth and rough. Interestingly, M. tuberculosis exists in only a rough form. The shift from smooth to rough in both M. smegmatis and M. abscessus was observed over time in extended static culture, however the frequency of the rough morphotype was high in pellicle preparations compared to planktonic culture, suggesting a role for an aggregated microenvironment in the shift to the rough form. Differences in growth rate, biofilm formation, cell wall composition, and drug tolerance were noted among M. smegmatis and M. abscessus variants. Deletion of the global regulator lsr2 shifted the M. smegmatis intermediate morphotype to a smooth form but did not fully phenocopy the naturally generated smooth morphotype, indicating Lsr2 is likely downstream of the initiating regulatory cascade that controls these morphotypes. Rough forms typically correlate with higher invasiveness and worse outcomes during infection and our findings indicate the shift to this rough form is promoted by aggregation. Our findings suggest that mycobacterial population heterogeneity, reflected in colony morphotypes, is a reproducible, programmed phenomenon that plays a role in adaptation to unique environments and this heterogeneity may influence infection progression and response to treatment.
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Affiliation(s)
- Sarah E. M. Born
- Department of Immunology and Microbiology, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Matthew J. Reichlen
- Department of Immunology and Microbiology, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Iona L. Bartek
- Department of Immunology and Microbiology, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Jeanne B. Benoit
- Division of Infectious Diseases, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Daniel N. Frank
- Division of Infectious Diseases, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Martin I. Voskuil
- Department of Immunology and Microbiology, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
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Cao L, Lu M, Zhao M, Zhang Y, Nong Y, Hu M, Wang Y, Li T, Chen F, Wang M, Liu J, Li E, Sun H. Physiological and transcriptional studies reveal Cr(VI) reduction mechanisms in the exoelectrogen Cellulomonas fimi Clb-11. Front Microbiol 2023; 14:1161303. [PMID: 37303804 PMCID: PMC10251745 DOI: 10.3389/fmicb.2023.1161303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Accepted: 04/24/2023] [Indexed: 06/13/2023] Open
Abstract
A facultative exoelectrogen, Cellulomonas fimi strain Clb-11, was isolated from polluted river water. This strain could generate electricity in microbial fuel cells (MFCs) with carboxymethyl cellulose (CMC) as the carbon source, and the maximum output power density was 12.17 ± 2.74 mW·m-2. In addition, Clb-11 could secrete extracellular chromate reductase or extracellular electron mediator to reduce Cr(VI) to Cr(III). When the Cr(VI) concentration was less than 0.5 mM in Luria-Bertani (LB) medium, Cr(VI) could be completely reduced by Clb-11. However, the Clb-11 cells swelled significantly in the presence of Cr(VI). We employed transcriptome sequencing analysis to identify genes involved in different Cr(VI) stress responses in Clb-11. The results indicate that 99 genes were continuously upregulated while 78 genes were continuously downregulated as the Cr(VI) concentration increased in the growth medium. These genes were mostly associated with DNA replication and repair, biosynthesis of secondary metabolites, ABC transporters, amino sugar and nucleotide sugar metabolism, and carbon metabolism. The swelling of Clb-11 cells might have been related to the upregulation of the genes atoB, INO1, dhaM, dhal, dhak, and bccA, which encode acetyl-CoA C-acetyltransferase, myo-inositol-1-phosphate synthase, phosphoenolpyruvate-glycerone phosphotransferase, and acetyl-CoA/propionyl-CoA carboxylase, respectively. Interestingly, the genes cydA and cydB related to electron transport were continuously downregulated as the Cr(VI) concentration increased. Our results provide clues to the molecular mechanism of Cr(VI) reduction by microorganisms in MFCs systems.
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Enhanced immunogenicity of Mycobacterium bovis BCG through CRISPRi mediated depletion of AftC. Cell Surf 2022; 8:100088. [PMID: 36405350 PMCID: PMC9651938 DOI: 10.1016/j.tcsw.2022.100088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 11/08/2022] [Accepted: 11/08/2022] [Indexed: 11/13/2022] Open
Abstract
Mycobacterium tuberculosis causes the disease tuberculosis and affects a third of the world’s population. The recent COVID-19 pandemic exacerbated the situation with a projected 27% increase in tuberculosis related deaths. M. tuberculosis has an elaborate cell wall consisting of peptidoglycan, arabinogalactan and mycolic acids which shield the bacilli from the toxic bactericidal milieu within phagocytes. Amongst, the numerous glycosyltransferase enzymes involved in mycobacterial cell wall biosynthesis, arabinofuranosyltransferase C (aftC) is responsible for the branching of the arabinan domain in both arabinogalactan and lipoarabinomannan. Using Clustered Regularly Interspaced Short Palindromic Repeats interference (CRISPRi) we have generated aftC knockdowns in Mycobacterium bovis BCG and demonstrated the generation of a truncated, immunogenic lipoarabinomannan within its cell envelope. The aftC depleted BCG mutants were unable to form characteristic mycobacterial pellicular biofilms and elicit a potent immunostimulatory phenotype compared to wild type M. bovis BCG in a THP1 cell line. This study paves the way to further explore novel BCG mutants as promising vaccine boosters in preventing pulmonary tuberculosis.
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Zhang Z, Yang Z, Zhen J, Xiang X, Liao P, Xie J. Insertion Mutation of MSMEG_0392 Play an Important Role in Resistance of M. smegmatis to Mycobacteriophage SWU1. Infect Drug Resist 2022; 15:347-357. [PMID: 35140480 PMCID: PMC8818766 DOI: 10.2147/idr.s341494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 01/21/2022] [Indexed: 11/23/2022] Open
Abstract
Purpose Phage is a new choice for the treatment of multi-drug-resistant bacteria, and phage resistance is also an issue of concern. SWU1 is a mycobacteriophage, and the mechanism of its resistance remain poorly understood. Methods The mutant strains which were stably resistant to SWU1 were screened by transposon mutation library. The stage of phage resistance was observed by transmission electron microscope (TEM). The insertion site of transposon was identified by thermal asymmetric interlaced PCR (TAIL-PCR). The possible relationship between insertion site and phage resistance was verified by gene knockout technique. The fatty acid composition of bacterial cell wall was analyzed by Gas Chromatography-Mass Spectrometer (GC-MS). Through the amplification and sequencing of target genes and gene complement techniques to find the mechanism of SWU1 resistance. Results The transposon mutant M12 which was stably resistant to mycobacteriophage SWU1 was successfully screened. It was confirmed that resistance occurred in the adsorption stage of bacteriophage. It was verified that the insertion site of the transposon was located in the MSMEG_3705 gene, but after knocking out the gene in the wild type M. smegmatis mc2 155, the resistance of the knockout strain to SWU1 was not observed. Through the amplification and sequencing of the target gene MSMEG_0392, it was found that there was an adenine insertion mutation at position 817. After complementing MSMEG_0392 in M12, it was found that M12 returned to sensitivity to SWU1. Conclusion We confirmed that the resistance of M12 to SWU1 was related to the functional inactivation of MSMEG_0392 and this phenomenon may be caused by the change of cell wall of M. smegmatis.
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Affiliation(s)
- Zhen Zhang
- Department of Clinical Laboratory, Chongqing General Hospital, University of Chinese Academy of Sciences, Chongqing, People’s Republic of China
- Institute of Modern Biopharmaceuticals, State Key Laboratory Breeding Base of Three Gorges Eco-Environment and Bioresources, Eco-Environment Key Laboratory of the Three Gorges Reservoir Region, Ministry of Education, School of Life Sciences, Southwest University, Chongqing, 400715, People’s Republic of China
| | - Zhulan Yang
- Department of Clinical Laboratory, Southwest Hospital, Army Medical University, Chongqing, People’s Republic of China
| | - Junfeng Zhen
- Department of Clinical Laboratory, Chongqing General Hospital, University of Chinese Academy of Sciences, Chongqing, People’s Republic of China
| | - Xiaohong Xiang
- School of Pharmacy, Chongqing Medical and Pharmaceutical College, Chongqing, People’s Republic of China
| | - Pu Liao
- Department of Clinical Laboratory, Chongqing General Hospital, University of Chinese Academy of Sciences, Chongqing, People’s Republic of China
| | - Jianping Xie
- Institute of Modern Biopharmaceuticals, State Key Laboratory Breeding Base of Three Gorges Eco-Environment and Bioresources, Eco-Environment Key Laboratory of the Three Gorges Reservoir Region, Ministry of Education, School of Life Sciences, Southwest University, Chongqing, 400715, People’s Republic of China
- Correspondence: Jianping Xie; Pu Liao, Tel/Fax +8623-68367108, Email ;
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