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Gurung V, Biswas S, Biswas I. Diverse nature of ClpX degradation motifs in Streptococcus mutans. Microbiol Spectr 2024; 12:e0345723. [PMID: 38051052 PMCID: PMC10782952 DOI: 10.1128/spectrum.03457-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Accepted: 11/07/2023] [Indexed: 12/07/2023] Open
Abstract
IMPORTANCE Cytoplasmic Clp-related proteases play a major role in maintaining cellular proteome in bacteria. ClpX/P is one such proteolytic complex that is important for conserving protein homeostasis. In this study, we investigated the role of ClpX/P in Streptococcus mutans, an important oral pathogen. We identified several putative substrates whose cellular levels are regulated by ClpX/P in S. mutans and subsequently discovered several recognition motifs that are critical for degradation. Our study is the first comprehensive analysis of determining ClpX/P motifs in streptococci. We believe that identifying the substrates that are regulated by ClpX/P will enhance our understanding about virulence regulation in this important group of pathogens.
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Affiliation(s)
- Vivek Gurung
- Department of Microbiology, Molecular Genetics, and Immunology, University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Saswati Biswas
- Department of Microbiology, Molecular Genetics, and Immunology, University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Indranil Biswas
- Department of Microbiology, Molecular Genetics, and Immunology, University of Kansas Medical Center, Kansas City, Kansas, USA
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2
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Pedro NA, Fontebasso G, Pinto SN, Alves M, Mira NP. Acetate modulates the inhibitory effect of Lactobacillus gasseri against the pathogenic yeasts Candida albicans and Candida glabrata. MICROBIAL CELL (GRAZ, AUSTRIA) 2023; 10:88-102. [PMID: 37009625 PMCID: PMC10054710 DOI: 10.15698/mic2023.04.795] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 03/10/2023] [Accepted: 03/16/2023] [Indexed: 04/04/2023]
Abstract
The exploration of the interference prompted by commensal bacteria over fungal pathogens is an interesting alternative to develop new therapies. In this work we scrutinized how the presence of the poorly studied vaginal species Lactobacillus gasseri affects relevant pathophysiological traits of Candida albicans and Candida glabrata. L. gasseri was found to form mixed biofilms with C. albicans and C. glabrata resulting in pronounced death of the yeast cells, while bacterial viability was not affected. Reduced viability of the two yeasts was also observed upon co-cultivation with L. gasseri under planktonic conditions. Either in planktonic cultures or in biofilms, the anti-Candida effect of L. gasseri was augmented by acetate in a concentration-dependent manner. During planktonic co-cultivation the two Candida species counteracted the acidification prompted by L. gasseri thus impacting the balance between dissociated and undissociated organic acids. This feature couldn't be phenocopied in single-cultures of L. gasseri resulting in a broth enriched in acetic acid, while in the co-culture the non-toxic acetate prevailed. Altogether the results herein described advance the design of new anti-Candida therapies based on probiotics, in particular, those based on vaginal lactobacilli species, helping to reduce the significant burden that infections caused by Candida have today in human health.
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Affiliation(s)
- Nuno A. Pedro
- iBB, Institute for Bioengineering and Biosciences, Instituto Superior Técnico – Department of Bioengineering, Universidade de Lisboa, 1049-001 Lisboa, Portugal
- Associate Laboratory i4HB—Institute for Health and Bioeconomy at Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
| | - Gabriela Fontebasso
- iBB, Institute for Bioengineering and Biosciences, Instituto Superior Técnico – Department of Bioengineering, Universidade de Lisboa, 1049-001 Lisboa, Portugal
- Associate Laboratory i4HB—Institute for Health and Bioeconomy at Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
| | - Sandra N. Pinto
- iBB, Institute for Bioengineering and Biosciences, Instituto Superior Técnico – Department of Bioengineering, Universidade de Lisboa, 1049-001 Lisboa, Portugal
- Associate Laboratory i4HB—Institute for Health and Bioeconomy at Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
| | - Marta Alves
- CQE-Centro Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
| | - Nuno P. Mira
- iBB, Institute for Bioengineering and Biosciences, Instituto Superior Técnico – Department of Bioengineering, Universidade de Lisboa, 1049-001 Lisboa, Portugal
- Associate Laboratory i4HB—Institute for Health and Bioeconomy at Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
- * Corresponding Author: Nuno P Mira, Instituto Superior Técnico, Department of Bioengineering, University of Lisbon, Portugal; E-mail:
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Duncan RS, Keightley A, Lopez AA, Hall CW, Koulen P. Proteome changes in a human retinal pigment epithelial cell line during oxidative stress and following antioxidant treatment. Front Immunol 2023; 14:1138519. [PMID: 37153596 PMCID: PMC10154683 DOI: 10.3389/fimmu.2023.1138519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Accepted: 03/27/2023] [Indexed: 05/09/2023] Open
Abstract
Age related macular degeneration (AMD) is the most common cause of blindness in the elderly. Oxidative stress contributes to retinal pigment epithelium (RPE) dysfunction and cell death thereby leading to AMD. Using improved RPE cell model systems, such as human telomerase transcriptase-overexpressing (hTERT) RPE cells (hTERT-RPE), pathophysiological changes in RPE during oxidative stress can be better understood. Using this model system, we identified changes in the expression of proteins involved in the cellular antioxidant responses after induction of oxidative stress. Some antioxidants such as vitamin E (tocopherols and tocotrienols) are powerful antioxidants that can reduce oxidative damage in cells. Alpha-tocopherol (α-Toc or αT) and gamma-tocopherol (γ-Toc or γT) are well-studied tocopherols, but signaling mechanisms underlying their respective cytoprotective properties may be distinct. Here, we determined what effect oxidative stress, induced by extracellularly applied tBHP in the presence and absence of αT and/or γT, has on the expression of antioxidant proteins and related signaling networks. Using proteomics approaches, we identified differential protein expression in cellular antioxidant response pathways during oxidative stress and after tocopherol treatment. We identified three groups of proteins based on biochemical function: glutathione metabolism/transfer, peroxidases and redox-sensitive proteins involved in cytoprotective signaling. We found that oxidative stress and tocopherol treatment resulted in unique changes in these three groups of antioxidant proteins indicate that αT and γT independently and by themselves can induce the expression of antioxidant proteins in RPE cells. These results provide novel rationales for potential therapeutic strategies to protect RPE cells from oxidative stress.
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Affiliation(s)
- R. Scott Duncan
- Vision Research Center, Department of Ophthalmology, University of Missouri – Kansas City, School of Medicine, Kansas City, MO, United States
| | - Andrew Keightley
- Vision Research Center, Department of Ophthalmology, University of Missouri – Kansas City, School of Medicine, Kansas City, MO, United States
| | - Adam A. Lopez
- Vision Research Center, Department of Ophthalmology, University of Missouri – Kansas City, School of Medicine, Kansas City, MO, United States
| | - Conner W. Hall
- Vision Research Center, Department of Ophthalmology, University of Missouri – Kansas City, School of Medicine, Kansas City, MO, United States
| | - Peter Koulen
- Vision Research Center, Department of Ophthalmology, University of Missouri – Kansas City, School of Medicine, Kansas City, MO, United States
- Department of Biomedical Sciences, University of Missouri – Kansas City, School of Medicine, Kansas City, MO, United States
- *Correspondence: Peter Koulen,
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Abstract
Saccharibacteria (TM7), which are obligate episymbionts growing on the surface of host bacteria, may play an important role in oral disease, such as periodontitis (1, 2). As TM7 is a newly cultured lineage of bacteria, its research is limited by the small number of isolated representatives relative to the number of TM7 genomes assembled from culture-independent studies (3–5). A comprehensive view of both TM7 taxa and TM7 strain-level variations remains opaque. In this study, we expanded our previously developed TM7 baiting method into using many host bacteria in parallel, which allowed us to obtain 37 TM7 strains from the human oral cavity. These strains were further classified into low-enrichment (LE, n = 24) and high-enrichment (HE, n = 13) groups based on their proficiency at propagating on host bacteria. Of the 13 HE strains, 10 belong to “Candidatus Nanosynbacter sp.” strain HMT-352 (human microbial taxon) (6), enabling us to explore both the phenotypic and genomic strain variations within a single TM7 species. We show that TM7 HMT-352 strains exhibit a diverse host range and varied growth dynamics during the establishment of their episymbiotic relationship with host bacteria. Furthermore, despite HMT-352 strains sharing a majority of their genes, we identified several gene clusters that may play a pivotal role in host affinity. More importantly, our comparative analyses also provide TM7 gene candidates associated with strain-level phenotypic variation that may be important for episymbiotic interactions with host bacteria. IMPORTANCE Candidate phylum radiation (CPR) bacteria comprise a poorly understood phylum that is estimated to encompass ∼26% of all diversity of domain bacteria. Among CPR bacteria, the Saccharibacteria lineage (TM7) is of particular interest, as it is found in high abundance in the mammal microbiome and has been associated with oral disease. While many CPR genomes, TM7 included, have been acquired through culture-independent methods, only a small number of representatives have been isolated. Such isolated representatives, however, shed light on the physiology, pathogenesis, and episymbiotic interactions of TM7. Combined with genomic analyses, experiments involving isolated representatives can distinguish phylogenetic to phenotypic discrepancies and better identify genes of importance. In this study, we utilized multiple host bacteria in parallel to isolate TM7 bacteria and examined strain-level variation in TM7 to reveal key genes that may drive TM7-host interactions. Our findings accentuate that broad phylogenetic characterization of CPR is the next step in understanding these bacteria.
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Lacticaseibacillus rhamnosus: A Suitable Candidate for the Construction of Novel Bioengineered Probiotic Strains for Targeted Pathogen Control. Foods 2022; 11:foods11060785. [PMID: 35327208 PMCID: PMC8947445 DOI: 10.3390/foods11060785] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 03/03/2022] [Accepted: 03/07/2022] [Indexed: 12/12/2022] Open
Abstract
Probiotics, with their associated beneficial effects, have gained popularity for the control of foodborne pathogens. Various sources are explored with the intent to isolate novel robust probiotic strains with a broad range of health benefits due to, among other mechanisms, the production of an array of antimicrobial compounds. One of the shortcomings of these wild-type probiotics is their non-specificity. A pursuit to circumvent this limitation led to the advent of the field of pathobiotechnology. In this discipline, specific pathogen gene(s) are cloned and expressed into a given probiotic to yield a novel pathogen-specific strain. The resultant recombinant probiotic strain will exhibit enhanced species-specific inhibition of the pathogen and its associated infection. Such probiotics are also used as vehicles to deliver therapeutic agents. As fascinating as this approach is, coupled with the availability of numerous probiotics, it brings a challenge with regard to deciding which of the probiotics to use. Nonetheless, it is indisputable that an ideal candidate must fulfil the probiotic selection criteria. This review aims to show how Lacticaseibacillus rhamnosus, a clinically best-studied probiotic, presents as such a candidate. The objective is to spark researchers’ interest to conduct further probiotic-engineering studies using L. rhamnosus, with prospects for the successful development of novel probiotic strains with enhanced beneficial attributes.
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Biswas S, Dhaked HPS, Keightley A, Biswas I. Involvement of ClpE ATPase in Physiology of Streptococcus mutans. Microbiol Spectr 2021; 9:e0163021. [PMID: 34851151 PMCID: PMC8635124 DOI: 10.1128/spectrum.01630-21] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 11/01/2021] [Indexed: 11/25/2022] Open
Abstract
Streptococcus mutans, a dental pathogen, harbors at least three Clp ATPases (ClpC, ClpE, and ClpX) that form complexes with ClpP protease and participate in regulated proteolysis. Among these, the function of ClpE ATPase is poorly understood. We have utilized an isogenic clpE-deficient strain derived from S. mutans UA159 and evaluated the role of ClpE in cellular physiology. We found that loss of ClpE leads to increased susceptibility against thiol stress but not to oxidative and thermal stress. Furthermore, we found that the mutant displays altered tolerance against some antibiotics and altered biofilm formation. We performed a label-free proteomic analysis by comparing the mutant with the wild-type UA159 strain under nonstressed conditions and found that ClpE modulates a relatively limited proteome in the cell compared to the proteomes modulated by ClpX and ClpP. Nevertheless, we found that ClpE deficiency leads to an overabundance of some cell wall synthesis enzymes, ribosomal proteins, and an unknown protease encoded by SMU.2153. Our proteomic data strongly support some of the stress-related phenotypes that we observed. Our study emphasizes the significance of ClpE in the physiology of S. mutans. IMPORTANCE When bacteria encounter environmental stresses, the expression of various proteins collectively known as heat shock proteins is induced. These heat shock proteins are necessary for cell survival specifically under conditions that induce protein denaturation. A subset of heat shock proteins known as the Clp proteolytic complex is required for the degradation of the misfolded proteins in the cell. The Clp proteolytic complex contains an ATPase and a protease. A specific Clp ATPase, ClpE, is uniquely present in Gram-positive bacteria, including streptococci. Here, we have studied the functional role of the ClpE protein in Streptococcus mutans, a dental pathogen. Our results suggest that ClpE is required for survival under certain antibiotic exposure and stress conditions but not others. Our results demonstrate that loss of ClpE leads to a significantly altered cellular proteome, and the analysis of those changes suggests that ClpE's functions in S. mutans are different from its functions in other Gram-positive bacteria.
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Affiliation(s)
- Saswati Biswas
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Hemendra Pal Singh Dhaked
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Andrew Keightley
- Department of Ophthalmology, University of Missouri School of Medicine, Kansas City, Missouri, USA
| | - Indranil Biswas
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, Kansas, USA
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Exoproteome Analysis of Antagonistic Interactions between the Probiotic Bacteria Limosilactobacillus reuteri LR1 and Lacticaseibacillus rhamnosus F and Multidrug Resistant Strain of Klebsiella pneumonia. Int J Mol Sci 2021; 22:ijms222010999. [PMID: 34681658 PMCID: PMC8537075 DOI: 10.3390/ijms222010999] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 10/06/2021] [Accepted: 10/08/2021] [Indexed: 12/21/2022] Open
Abstract
The expansion of multiple drug resistant (MDR) strains of Klebsiella pneumoniae presents an immense threat for public health. Annually, this microorganism causes thousands of lethal nosocomial infections worldwide. Currently, it has been shown that certain strains of lactic acid bacteria (LAB) can efficiently inhibit growth of K. pneumoniae and the formation of its biofilms; however, the active principle of such action remains unknown. In the current article, the growth inhibition of MDR K. pneumoniae by two LAB—Limosilactobacillus reuteri LR1 and Lacticaseibacillus rhamnosus F—is demonstrated, and the nature of this inhibition studied at the level of exoproteome. This article shows that the exoproteomes of studied LAB contains both classically and non-classically secreted proteins. While for L. reuteri LR1 the substantial portion of classically secreted proteins was presented by cell-wall-degrading enzymes, for L. rhamnosus F only one out of four classically secreted proteins was presented by cell-wall hydrolase. Non-classically secreted proteins of both LAB were primarily metabolic enzymes, for some of which a possible moonlighting functioning was proposed. These results contribute to knowledge regarding antagonistic interaction between LAB and pathogenic and opportunistic microorganisms and set new perspectives for the use of LAB to control the spread of these microorganisms.
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Martínez B, Rodríguez A, Kulakauskas S, Chapot-Chartier MP. Cell wall homeostasis in lactic acid bacteria: threats and defences. FEMS Microbiol Rev 2021; 44:538-564. [PMID: 32495833 PMCID: PMC7476776 DOI: 10.1093/femsre/fuaa021] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 06/03/2020] [Indexed: 12/16/2022] Open
Abstract
Lactic acid bacteria (LAB) encompasses industrially relevant bacteria involved in food fermentations as well as health-promoting members of our autochthonous microbiota. In the last years, we have witnessed major progresses in the knowledge of the biology of their cell wall, the outermost macrostructure of a Gram-positive cell, which is crucial for survival. Sophisticated biochemical analyses combined with mutation strategies have been applied to unravel biosynthetic routes that sustain the inter- and intra-species cell wall diversity within LAB. Interplay with global cell metabolism has been deciphered that improved our fundamental understanding of the plasticity of the cell wall during growth. The cell wall is also decisive for the antimicrobial activity of many bacteriocins, for bacteriophage infection and for the interactions with the external environment. Therefore, genetic circuits involved in monitoring cell wall damage have been described in LAB, together with a plethora of defence mechanisms that help them to cope with external threats and adapt to harsh conditions. Since the cell wall plays a pivotal role in several technological and health-promoting traits of LAB, we anticipate that this knowledge will pave the way for the future development and extended applications of LAB.
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Affiliation(s)
- Beatriz Martínez
- DairySafe research group. Department of Technology and Biotechnology of Dairy Products. Instituto de Productos Lácteos de Asturias, IPLA-CSIC. Paseo Río Linares s/n. 33300 Villaviciosa, Spain
| | - Ana Rodríguez
- DairySafe research group. Department of Technology and Biotechnology of Dairy Products. Instituto de Productos Lácteos de Asturias, IPLA-CSIC. Paseo Río Linares s/n. 33300 Villaviciosa, Spain
| | - Saulius Kulakauskas
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, 78350, Jouy-en-Josas, France
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Dadfarma N, Karimi G, Nowroozi J, Nejadi N, Kazemi B, Bandehpour M. Proteomic analysis of Lactobacillus casei in response to different pHs using two-dimensional electrophoresis and MALDI TOF mass spectroscopy. IRANIAN JOURNAL OF MICROBIOLOGY 2020; 12:431-436. [PMID: 33603998 PMCID: PMC7867702 DOI: 10.18502/ijm.v12i5.4604] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Background and Objectives: Lactobacillus casei, an acid-resistant bacterium, has a protective role against the pathogens. So we aimed to determine the proteome of Lactobacillus casei ATCC39392 strain in response to different pHs of 5 and 7 using proteomic analysis. Materials and Methods: Supernatant and bacterial extraction of Lactobacillus casei ATCC39392 adapts at pHs 5 and 7 were isolated using sodium dodecyl sulfate–polyacrylamide gel and two-dimensional gel electrophoresis. The comparison of results showed that 7 protein spots were seen in pH 5 but not in pH 7. Afterward, they were excised and sent for Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) to be identified. Results: Seven different proteins (four secretory and three structural) with different roles in human body health were identified. Prescribed proteins include putative cell wall associated Hydrolase, Glycoside Hydrolase, beta-N-Acetyl hexosaminidase, Histidine Kinase, Chaperonin, metal dependent Hydrolase and Lysozyme. Conclusion: Seven isolated proteins with anti-cancer and digestive impresses are proper subjects in therapy or drug delivery approaches especially oral drug usage for protection against stomach acidic area.
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Affiliation(s)
- Narges Dadfarma
- Department of Microbiology, North Tehran Branch, Islamic Azad University, Tehran, Iran
| | - Golgis Karimi
- Cellular and Molecular Biology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Jamileh Nowroozi
- Department of Microbiology, North Tehran Branch, Islamic Azad University, Tehran, Iran
| | - Naser Nejadi
- Proteomics Research Center, School of Paramedical Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Bahram Kazemi
- Cellular and Molecular Biology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mojgan Bandehpour
- Department of Medical Biotechnology, School of Advanced Technologies in Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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Abstract
Species belonging to the family Lactobacillaceae are found in highly diverse environments and play an important role in fermented foods and probiotic products. Many of these species have been individually reported to harbour plasmids that encode important genes. In this study, we performed comparative genomic analysis of publicly available data for 512 plasmids from 282 strains represented by 51 species of this family and correlated the genomic features of plasmids with the ecological niches in which these species are found. Two-thirds of the species had at least one plasmid-harbouring strain. Plasmid abundance and GC content were significantly lower in vertebrate-adapted species as compared to nomadic and free-living species. Hierarchical clustering highlighted the distinct nature of plasmids from the nomadic and free-living species than those from the vertebrate-adapted species. EggNOG-assisted functional annotation revealed that genes associated with transposition, conjugation, DNA repair and recombination, exopolysaccharide production, metal ion transport, toxin–antitoxin system, and stress tolerance were significantly enriched on the plasmids of the nomadic and in some cases nomadic and free-living species. On the other hand, genes related to anaerobic metabolism, ABC transporters and the major facilitator superfamily were overrepresented on the plasmids of the vertebrate-adapted species. These genomic signatures correlate with the comparatively nutrient-depleted, stressful and dynamic environments of nomadic and free-living species and nutrient-rich and anaerobic environments of vertebrate-adapted species. Thus, these results indicate the contribution of the plasmids in the adaptation of lactobacilli to their respective habitats. This study also underlines the potential application of these plasmids in improving the technological and probiotic properties of lactic acid bacteria.
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Affiliation(s)
- Dimple Davray
- Symbiosis School of Biological Sciences, Symbiosis International (Deemed University), Lavale, Pune 412115, India
| | - Dipti Deo
- Symbiosis School of Biological Sciences, Symbiosis International (Deemed University), Lavale, Pune 412115, India
| | - Ram Kulkarni
- Symbiosis School of Biological Sciences, Symbiosis International (Deemed University), Lavale, Pune 412115, India
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Biswas S, Keightley A, Biswas I. Ribosomal protein L4 of Lactobacillus rhamnosus LRB alters resistance to macrolides and other antibiotics. Mol Oral Microbiol 2020; 35:106-119. [PMID: 32022979 DOI: 10.1111/omi.12281] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2019] [Revised: 01/23/2020] [Accepted: 02/03/2020] [Indexed: 01/09/2023]
Abstract
Lactobacillus rhamnosus is an important lactic acid bacterium that is predominantly used as a probiotic supplement. This bacterium secretes immunomodulatory and antibacterial peptides that are necessary for the probiotic trait. This organism also occupies diverse ecological niches, such as gastrointestinal tracts and the oral cavity. Several studies have shown that L. rhamnosus is prone to spontaneous genome rearrangement irrespective of the ecological origins. We previously characterized an oral isolate of L. rhamnosus, LRB, which is genetically closely related to the widely used probiotic strain L. rhamnosus LGG. In this study, we isolated a nontargeted mutant that was particularly sensitive to acid stress. Using next generation sequencing, we further mapped the putative mutations in the genome and found that the mutant had acquired a deletion of 75 base pairs in the rplD gene that encodes the large ribosomal subunit L4. The mutant had a growth defect at 37°C and at ambient temperature. Further antibiotic sensitivity analyses indicated that the mutant is relatively more resistant to erythromycin and chloramphenicol; two antibiotics that target the 50S subunit. In contrast, the mutant was more sensitive to tetracycline, which targets the 30S subunit. Thus, it appears that nontargeted mutations could significantly alter the antibiotic resistance profile of L. rhamnosus. Our study raises concern that probiotic use of L. rhamnosus should be carefully monitored to avoid unintended consequences.
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Affiliation(s)
- Saswati Biswas
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, KS, USA
| | - Andrew Keightley
- Mass Spectrometry and Proteomics, UMKC School of Biological Sciences, Kansas City, MO, USA
| | - Indranil Biswas
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, KS, USA
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