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Li D, Ren Z, Zhou Y, Jiang L, Zheng M, Liu G. Comammox Nitrospira and Ammonia-Oxidizing Archaea Are Dominant Ammonia Oxidizers in Sediments of an Acid Mine Lake Containing High Ammonium Concentrations. Appl Environ Microbiol 2023; 89:e0004723. [PMID: 36912626 PMCID: PMC10056971 DOI: 10.1128/aem.00047-23] [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: 01/13/2023] [Accepted: 01/31/2023] [Indexed: 03/14/2023] Open
Abstract
Exploring nitrifiers in extreme environments is vital to expanding our understanding of nitrogen cycle and microbial diversity. This study presents that complete ammonia oxidation (comammox) Nitrospira, together with acidophilic ammonia-oxidizing archaea (AOA), dominate in the nitrifying guild in sediments of an acid mine lake (AML). The lake water was characterized by acidic pH below 5 with a high ammonium concentration of 175 mg-N/liter, which is rare on the earth. Nitrification was active in sediments with a maximum nitrate production potential of 70.5 μg-N/(g-dry weight [dw] day) for mixed sediments. Quantitative PCR assays determined that in AML sediments, comammox Nitrospira and AOA amoA genes had relative abundances of 52% and 41%, respectively, among the total amoA genes. Further assays with 16S rRNA and amoA gene amplicon sequencing and metagenomics confirmed their dominance and revealed that the comammox Nitrospira found in sediments belonged to comammox Nitrospira clade A.2. Metagenomic binning retrieved a metagenome-assembled genome (MAG) of the comammox Nitrospira from sediments (completeness = 96.76%), and phylogenomic analysis suggested that it was a novel comammox Nitrospira. Comparative genomic investigation revealed that this comammox Nitrospira contained diverse metal resistance genes and an acidophile-affiliated F-type ATPase. Moreover, it had a more diverse genomic characteristic on nitrogen metabolism than the AOA in sediments and canonical AOB did. The results suggest that comammox Nitrospira is a versatile nitrifier that can adapt to acidic environments even with high ammonium concentrations. IMPORTANCE Ammonia-oxidizing archaea (AOA) was previously considered the sole dominant ammonia oxidizer in acidic environments. This study, however, found that complete ammonia oxidation (comammox) Nitrospira was also a dominant ammonia oxidizer in the sediments of an acidic mine lake, which had an acidic pH < 5 and a high ammonium concentration of 175 mg-N/liter. In combination with average nucleotide identity analysis, phylogenomic analysis suggested it is a novel strain of comammox Nitrospira. Moreover, the adaption of comammox Nitrospira to the acidic lake had been comprehensively investigated based on genome-centric metagenomic approaches. The outcomes of this study significantly expand our understanding of the diversity and adaptability of ammonia oxidizers in the acidic environments.
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Affiliation(s)
- Deyong Li
- Center for Environmental Microplastics Studies, Guangdong Engineering Research Center of Water Treatment Processes and Materials, Guangdong Key Laboratory of Environmental Pollution and Health, and School of Environment, Jinan University, Guangzhou, and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, China
| | - Zhichang Ren
- Center for Environmental Microplastics Studies, Guangdong Engineering Research Center of Water Treatment Processes and Materials, Guangdong Key Laboratory of Environmental Pollution and Health, and School of Environment, Jinan University, Guangzhou, and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, China
| | - Yangqi Zhou
- Center for Environmental Microplastics Studies, Guangdong Engineering Research Center of Water Treatment Processes and Materials, Guangdong Key Laboratory of Environmental Pollution and Health, and School of Environment, Jinan University, Guangzhou, and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, China
| | - Lugao Jiang
- Center for Environmental Microplastics Studies, Guangdong Engineering Research Center of Water Treatment Processes and Materials, Guangdong Key Laboratory of Environmental Pollution and Health, and School of Environment, Jinan University, Guangzhou, and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, China
| | - Min Zheng
- Australian Centre for Water and Environmental Biotechnology (ACWEB, formerly AWMC), University of Queensland, St. Lucia, Brisbane, Queensland, Australia
| | - Guoqiang Liu
- Center for Environmental Microplastics Studies, Guangdong Engineering Research Center of Water Treatment Processes and Materials, Guangdong Key Laboratory of Environmental Pollution and Health, and School of Environment, Jinan University, Guangzhou, and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, China
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2
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Schwarz J, Schumacher K, Brameyer S, Jung K. Bacterial battle against acidity. FEMS Microbiol Rev 2022; 46:6652135. [PMID: 35906711 DOI: 10.1093/femsre/fuac037] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2022] [Revised: 07/11/2022] [Accepted: 07/27/2022] [Indexed: 01/09/2023] Open
Abstract
The Earth is home to environments characterized by low pH, including the gastrointestinal tract of vertebrates and large areas of acidic soil. Most bacteria are neutralophiles, but can survive fluctuations in pH. Herein, we review how Escherichia, Salmonella, Helicobacter, Brucella, and other acid-resistant Gram-negative bacteria adapt to acidic environments. We discuss the constitutive and inducible defense mechanisms that promote survival, including proton-consuming or ammonia-producing processes, cellular remodeling affecting membranes and chaperones, and chemotaxis. We provide insights into how Gram-negative bacteria sense environmental acidity using membrane-integrated and cytosolic pH sensors. Finally, we address in more detail the powerful proton-consuming decarboxylase systems by examining the phylogeny of their regulatory components and their collective functionality in a population.
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Affiliation(s)
- Julia Schwarz
- Faculty of Biology, Microbiology, Ludwig-Maximilians-University München, Großhaderner Str. 2-4, 82152 Martinsried, Germany
| | - Kilian Schumacher
- Faculty of Biology, Microbiology, Ludwig-Maximilians-University München, Großhaderner Str. 2-4, 82152 Martinsried, Germany
| | - Sophie Brameyer
- Faculty of Biology, Microbiology, Ludwig-Maximilians-University München, Großhaderner Str. 2-4, 82152 Martinsried, Germany
| | - Kirsten Jung
- Faculty of Biology, Microbiology, Ludwig-Maximilians-University München, Großhaderner Str. 2-4, 82152 Martinsried, Germany
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3
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Jin X, Zhou M, Chen S, Li D, Cao X, Liu B. Effects of pH alterations on stress- and aging-induced protein phase separation. Cell Mol Life Sci 2022; 79:380. [PMID: 35750966 PMCID: PMC9232405 DOI: 10.1007/s00018-022-04393-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 04/26/2022] [Accepted: 05/21/2022] [Indexed: 01/18/2023]
Abstract
Upon stress challenges, proteins/RNAs undergo liquid–liquid phase separation (LLPS) to fine-tune cell physiology and metabolism to help cells adapt to adverse environments. The formation of LLPS has been recently linked with intracellular pH, and maintaining proper intracellular pH homeostasis is known to be essential for the survival of organisms. However, organisms are constantly exposed to diverse stresses, which are accompanied by alterations in the intracellular pH. Aging processes and human diseases are also intimately linked with intracellular pH alterations. In this review, we summarize stress-, aging-, and cancer-associated pH changes together with the mechanisms by which cells regulate cytosolic pH homeostasis. How critical cell components undergo LLPS in response to pH alterations is also discussed, along with the functional roles of intracellular pH fluctuation in the regulation of LLPS. Further studies investigating the interplay of pH with other stressors in LLPS regulation and identifying protein responses to different pH levels will provide an in-depth understanding of the mechanisms underlying pH-driven LLPS in cell adaptation. Moreover, deciphering aging and disease-associated pH changes that influence LLPS condensate formation could lead to a deeper understanding of the functional roles of biomolecular condensates in aging and aging-related diseases.
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Affiliation(s)
- Xuejiao Jin
- State Key Laboratory of Subtropical Silviculture, School of Forestry and Biotechnology, Zhejiang A&F University, Lin'an, Hangzhou, 311300, China
| | - Min Zhou
- State Key Laboratory of Subtropical Silviculture, School of Forestry and Biotechnology, Zhejiang A&F University, Lin'an, Hangzhou, 311300, China
| | - Shuxin Chen
- State Key Laboratory of Subtropical Silviculture, School of Forestry and Biotechnology, Zhejiang A&F University, Lin'an, Hangzhou, 311300, China
| | - Danqi Li
- State Key Laboratory of Subtropical Silviculture, School of Forestry and Biotechnology, Zhejiang A&F University, Lin'an, Hangzhou, 311300, China
| | - Xiuling Cao
- State Key Laboratory of Subtropical Silviculture, School of Forestry and Biotechnology, Zhejiang A&F University, Lin'an, Hangzhou, 311300, China.
| | - Beidong Liu
- State Key Laboratory of Subtropical Silviculture, School of Forestry and Biotechnology, Zhejiang A&F University, Lin'an, Hangzhou, 311300, China. .,Department of Chemistry and Molecular Biology, University of Gothenburg, Medicinaregatan 9C, 413 90, Goteborg, Sweden. .,Center for Large-Scale Cell-Based Screening, Faculty of Science, University of Gothenburg, Medicinaregatan 9C, 413 90, Goteborg, Sweden.
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4
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Policastro G, Carraturo F, Compagnone M, Giugliano M, Guida M, Luongo V, Napolitano R, Fabbricino M. A preliminary study on a novel bioaugmentation technique enhancing lactic acid production by mixed cultures fermentation. BIORESOURCE TECHNOLOGY 2021; 340:125595. [PMID: 34333344 DOI: 10.1016/j.biortech.2021.125595] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 07/13/2021] [Accepted: 07/14/2021] [Indexed: 06/13/2023]
Abstract
The paper is a preliminary study on the selection of lactic acid producing microorganisms from a mixed microbial population via bioaugmentation. The bioaugmentation technique is based on pH sudden variations occurring in sequential batch steps of a dark fermentation process applied to simple substrates. Different conditions are tested and compared. The structure of microbial communities and concentrations of metabolic intermediates are analyzed to study the possible substrate conversion routes. Obtained results indicate that the initial mixed culture produced a lactic acid percentage of 5% in terms of CODLA/CODPRODUCTS. In the most favourable conditions, the selected culture produced a lactic acid percentage of 59%. The analysis of the composition of microbial communities before and after the bioaugmentation processes, indicates that lactic acid production mainly results from the population change to bacteria belonging to the genus Bacillus. Indeed, the relative abundance of Bacilli increased from 0.67%, to 8.40% during the bioaugmentation cycle.
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Affiliation(s)
- Grazia Policastro
- Department of Civil, Architectural and Environmental Engineering, University of Naples Federico II, via Claudio 21, Naples 80125, Italy.
| | - Federica Carraturo
- Department of Biology, University of Naples Federico II, via Cintia 21, Naples 80126, Italy.
| | - Mariacristina Compagnone
- Department of Chemical Engineering and Food Technologies, Faculty of Sciences, University of Cádiz, 11510 Puerto Real, Cádiz, Spain.
| | - Marco Giugliano
- Department of Civil, Architectural and Environmental Engineering, University of Naples Federico II, via Claudio 21, Naples 80125, Italy.
| | - Marco Guida
- Department of Biology, University of Naples Federico II, via Cintia 21, Naples 80126, Italy.
| | - Vincenzo Luongo
- Department of Mathematics and Applications Renato Caccioppoli, University of Naples Federico II, via Cintia, Monte S. Angelo, Naples I-80126, Italy.
| | - Raffaele Napolitano
- Department of Civil, Architectural and Environmental Engineering, University of Naples Federico II, via Claudio 21, Naples 80125, Italy.
| | - Massimiliano Fabbricino
- Department of Civil, Architectural and Environmental Engineering, University of Naples Federico II, via Claudio 21, Naples 80125, Italy.
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5
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Hu W, Feng S, Tong Y, Zhang H, Yang H. Adaptive defensive mechanism of bioleaching microorganisms under extremely environmental acid stress: Advances and perspectives. Biotechnol Adv 2020; 42:107580. [DOI: 10.1016/j.biotechadv.2020.107580] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2020] [Revised: 05/26/2020] [Accepted: 06/18/2020] [Indexed: 12/13/2022]
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6
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Ikeyama N, Murakami T, Toyoda A, Mori H, Iino T, Ohkuma M, Sakamoto M. Microbial interaction between the succinate-utilizing bacterium Phascolarctobacterium faecium and the gut commensal Bacteroides thetaiotaomicron. Microbiologyopen 2020; 9:e1111. [PMID: 32856395 PMCID: PMC7568257 DOI: 10.1002/mbo3.1111] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 07/21/2020] [Accepted: 07/31/2020] [Indexed: 12/17/2022] Open
Abstract
A large variety of microbes are present in the human gut, some of which are considered to interact with each other. Most of these interactions involve bacterial metabolites. Phascolarctobacterium faecium hardly uses carbohydrates for growth and instead uses succinate as a substrate. This study investigated the growth behavior of the co‐culture of the succinate‐specific utilizer P. faecium and the succinogenic gut commensal Bacteroides thetaiotaomicron. Succinate production by B. thetaiotaomicron supported the growth of P. faecium and concomitant propionate production via the succinate pathway. The succinate produced was completely converted to propionate. This result was comparable with the monoculture of P. faecium in the medium supplemented with 1% (w/v) succinate. We analyzed the transcriptional response (RNA‐Seq) between the mono‐ and co‐culture of P. faecium and B. thetaiotaomicron. Comparison of the expression levels of genes of P. faecium between the mono‐ and co‐cultured conditions highlighted that the genes putatively involved in the transportation of succinate were notably expressed under the co‐cultured conditions. Differential expression analysis showed that the presence of P. faecium induced changes in the B. thetaiotaomicron transcriptional pattern, for example, expression changes in the genes for vitamin B12 transporters and reduced expression of glutamate‐dependent acid resistance system‐related genes. Also, transcriptome analysis of P. faecium suggested that glutamate and succinate might be used as sources of succinyl‐CoA, an intermediate in the succinate pathway. This study revealed some survival strategies of asaccharolytic bacteria, such as Phascolarctobacterium spp., in the human gut.
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Affiliation(s)
- Nao Ikeyama
- Microbe Division/Japan Collection of Microorganisms, RIKEN BioResource Research Center, Tsukuba, Ibaraki, Japan
| | - Takumi Murakami
- Advanced Genomics Center, National Institute of Genetics, Mishima, Shizuoka, Japan
| | - Atsushi Toyoda
- Advanced Genomics Center, National Institute of Genetics, Mishima, Shizuoka, Japan
| | - Hiroshi Mori
- Advanced Genomics Center, National Institute of Genetics, Mishima, Shizuoka, Japan
| | - Takao Iino
- Microbe Division/Japan Collection of Microorganisms, RIKEN BioResource Research Center, Tsukuba, Ibaraki, Japan
| | - Moriya Ohkuma
- Microbe Division/Japan Collection of Microorganisms, RIKEN BioResource Research Center, Tsukuba, Ibaraki, Japan
| | - Mitsuo Sakamoto
- Microbe Division/Japan Collection of Microorganisms, RIKEN BioResource Research Center, Tsukuba, Ibaraki, Japan.,PRIME, Japan Agency for Medical Research and Development (AMED), Tsukuba, Ibaraki, Japan
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7
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Zhou C, Fey PD. The acid response network of Staphylococcus aureus. Curr Opin Microbiol 2020; 55:67-73. [PMID: 32361405 PMCID: PMC7311314 DOI: 10.1016/j.mib.2020.03.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2019] [Revised: 03/17/2020] [Accepted: 03/18/2020] [Indexed: 12/12/2022]
Abstract
Staphylococcus aureus colonizes or causes infection in a multitude of niches within a mammalian host. Many of these niches are acidic, yet specific pH resistance mechanisms that facilitate survival have not been thoroughly investigated. This review discusses recent studies documenting known acid resistance mechanisms in S. aureus and other staphylococcal species. However, studies that clearly define the regulation of the acid resistance regulon and potential interactions with weak organic acids in specific niches of the host including the skin and gut are yet to be defined.
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Affiliation(s)
- Chunyi Zhou
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, United States
| | - Paul D Fey
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, United States.
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8
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Tsujii T, Kawada-Matsuo M, Migita H, Ohta K, Oogai Y, Yamasaki Y, Komatsuzawa H. Antibacterial activity of phellodendron bark against Streptococcus mutans. Microbiol Immunol 2020; 64:424-434. [PMID: 32196736 DOI: 10.1111/1348-0421.12787] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Revised: 03/13/2020] [Accepted: 03/16/2020] [Indexed: 01/01/2023]
Abstract
Streptococcus mutans is a major cause of tooth decay due to its promotion of biofilm formation and acid production. Several plant extracts have been reported to have multiple biological activities such as anti-inflammation and antibacterial effects. This study investigated the antibacterial activity of three plant extracts, phellodendron bark (PB), yucca, and black ginger, and found that PB had a stronger effect than the other extracts. Then, the minimum inhibitory concentration (MIC) of PB against 100 S. mutans strains was investigated. The MIC range of PB was 9.8-312.5 µg/mL. PB suppressed the growth kinetics of S. mutans in a dose-dependent manner, even at sub-MICs of PB. Then, we investigated the effect of PB on S. mutans virulence. The PB suppressed biofilm formation at high concentrations, although PB did not affect the expression of glucosyltransferase genes. Additionally, PB suppressed the decrease in pH from adding an excess of glucose. The expression of genes responsible for acid production was increased by the addition of excess glucose without PB, whereas their expression levels were not increased in the presence of 1× and 2× MIC of PB. Although PB showed a bacteriostatic effect on planktonic S. mutans cells, it was found that more than 2× MIC of PB showed a partial bactericidal effect on biofilm cells. In conclusion, PB not only showed antibacterial activity against S. mutans but also decreased the cariogenic activity in S. mutans.
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Affiliation(s)
- Toshiya Tsujii
- Department of Pediatric Dentistry, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
- Department of Oral Microbiology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Miki Kawada-Matsuo
- Department of Oral Microbiology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
- Department of Bacteriology, Hiroshima University Graduate School of Biomedical and Health Sciences, Hiroshima, Japan
| | - Hirono Migita
- Department of Oral Microbiology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Kouji Ohta
- Department of Public Oral Health, Program of Oral Health Sciences, Hiroshima University Graduate School of Biomedical and Health Sciences, Hiroshima, Japan
| | - Yuichi Oogai
- Department of Oral Microbiology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Youichi Yamasaki
- Department of Pediatric Dentistry, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Hitoshi Komatsuzawa
- Department of Bacteriology, Hiroshima University Graduate School of Biomedical and Health Sciences, Hiroshima, Japan
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9
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Recent advances of pH homeostasis mechanisms in Corynebacterium glutamicum. World J Microbiol Biotechnol 2019; 35:192. [PMID: 31773365 DOI: 10.1007/s11274-019-2770-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Accepted: 11/13/2019] [Indexed: 12/31/2022]
Abstract
Corynebacterium glutamicum is generally regarded as a safe microorganism, and widely used in the large-scale production of various amino acids and organic acids, such as L-glutamate, L-lysine and succinic acid. During the process of industrial fermentation, C. glutamicum is usually exposed to varying environmental stresses, such as variations in pH, salinity, temperature, and osmolality. Among them, pH fluctuations are regarded as one of the most frequent environmental stresses in microbial fermentation. In this review, we summarize the current knowledge of pH homeostasis mechanisms adopted by C. glutamicum for coping with low acidic pH and high alkaline pH stresses. Facing with low pH environments, C. glutamicum develops a variety of strategies to maintain intracellular pH homeostasis, such as lowering intracellular reactive oxygen species, the improvement of potassium transport, the regulation of mycothiol-related pathways, as well as the repression of sulfur assimilation. While during alkaline pH stresses, the Mrp-type Na+/H+ antiporters are shown to play a dominant role in conferring C. glutamicum cells resistance to alkaline pH. Furthermore, we also discuss the general strategies and prospects on metabolic engineering of C. glutamicum to improve alkaline or acid resistance.
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10
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Yamashita T, Kawada-Matsuo M, Katsumata T, Watanabe A, Oogai Y, Nishitani Y, Miyawaki S, Komatsuzawa H. Antibacterial activity of disodium succinoyl glycyrrhetinate, a derivative of glycyrrhetinic acid against Streptococcus mutans. Microbiol Immunol 2019; 63:251-260. [PMID: 31166029 DOI: 10.1111/1348-0421.12717] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 05/09/2019] [Accepted: 05/23/2019] [Indexed: 11/28/2022]
Abstract
Streptococcus mutans is a cariogenic bacterium that localizes in the oral cavity. Glycyrrhetinic acid (GRA) is a major component of licorice extract. GRA and several derivatives, including disodium succinoyl glycyrrhetinate (GR-SU), are known to have anti-inflammatory effects in humans. In this study, the antimicrobial effect of GRA and its derivatives against the S. mutans UA159 strain were investigated. Minimum inhibitory concentrations (MICs) of GRA and GR-SU showed antibacterial activity against the S. mutans strain, whereas other tested derivatives did not. Because GR-SU is more soluble than GRA, GR-SU was used for further experiments. The antibacterial activity of GR-SU against 100 S. mutans strains was evaluated and it was found that all strains are susceptible to GR-SU, with MIC values below 256 µg/mL. A cell viability assay showed that GR-SU has a bacteriostatic effect on S. mutans cells. As to growth kinetics, sub-MICs of GR-SU inhibited growth. The effect of GR-SU on S. mutans virulence was then investigated. GR-SU at sub-MICs suppresses biofilm formation. Additionally, GR-SU greatly suppresses the pH drop caused by the addition of glucose and glucose-induced expression of the genes responsible for acid production (ldh and pykF) and tolerance (aguD and atpD). Additionally, expression of enolase, which is responsible for the carbohydrate phosphotransferase system, was not increased in the presence of GR-SU, indicating that GR-SU suppresses incorporation of sugars into S. mutans. In conclusion, GR-SU has antibacterial activity against S. mutans and also decreases S. mutans virulence.
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Affiliation(s)
- Takahito Yamashita
- Department of Oral Microbiology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Miki Kawada-Matsuo
- Department of Oral Microbiology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Tamaki Katsumata
- Department of Restorative Dentistry and Endodontology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Atsuko Watanabe
- Department of Orthodontics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Yuichi Oogai
- Department of Oral Microbiology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Yoshihiro Nishitani
- Department of Restorative Dentistry and Endodontology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Shouichi Miyawaki
- Department of Orthodontics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Hitoshi Komatsuzawa
- Department of Bacteriology, Hiroshima University Graduate School of Biomedical and Health Sciences, Hiroshima, Japan
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11
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Akanuma G, Tagana T, Sawada M, Suzuki S, Shimada T, Tanaka K, Kawamura F, Kato-Yamada Y. C-terminal regulatory domain of the ε subunit of F o F 1 ATP synthase enhances the ATP-dependent H + pumping that is involved in the maintenance of cellular membrane potential in Bacillus subtilis. Microbiologyopen 2019; 8:e00815. [PMID: 30809948 PMCID: PMC6692558 DOI: 10.1002/mbo3.815] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Revised: 01/16/2019] [Accepted: 01/18/2019] [Indexed: 01/23/2023] Open
Abstract
The ε subunit of FoF1‐ATPase/synthase (FoF1) plays a crucial role in regulating FoF1 activity. To understand the physiological significance of the ε subunit‐mediated regulation of FoF1 in Bacillus subtilis, we constructed and characterized a mutant harboring a deletion in the C‐terminal regulatory domain of the ε subunit (ε∆C). Analyses using inverted membrane vesicles revealed that the ε∆C mutation decreased ATPase activity and the ATP‐dependent H+‐pumping activity of FoF1. To enhance the effects of ε∆C mutation, this mutation was introduced into a ∆rrn8 strain harboring only two of the 10 rrn (rRNA) operons (∆rrn8 ε∆C mutant strain). Interestingly, growth of the ∆rrn8 ε∆C mutant stalled at late‐exponential phase. During the stalled growth phase, the membrane potential of the ∆rrn8 ε∆C mutant cells was significantly reduced, which led to a decrease in the cellular level of 70S ribosomes. The growth stalling was suppressed by adding glucose into the culture medium. Our findings suggest that the C‐terminal region of the ε subunit is important for alleviating the temporal reduction in the membrane potential, by enhancing the ATP‐dependent H+‐pumping activity of FoF1.
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Affiliation(s)
- Genki Akanuma
- Department of Life Science, College of Science, Rikkyo University, Toshima-ku, Tokyo, Japan.,Research Center for Life Science, College of Science, Rikkyo University, Toshima-ku, Tokyo, Japan
| | - Tomoaki Tagana
- Department of Life Science, College of Science, Rikkyo University, Toshima-ku, Tokyo, Japan
| | - Maho Sawada
- Department of Life Science, College of Science, Rikkyo University, Toshima-ku, Tokyo, Japan
| | - Shota Suzuki
- Department of Life Science, College of Science, Rikkyo University, Toshima-ku, Tokyo, Japan
| | - Tomohiro Shimada
- Laboratory for Chemistry and Life Science, Institute of Innovative Science, Tokyo Institute of Technology, Yokohama, Midori-ku, Japan
| | - Kan Tanaka
- Laboratory for Chemistry and Life Science, Institute of Innovative Science, Tokyo Institute of Technology, Yokohama, Midori-ku, Japan
| | - Fujio Kawamura
- Department of Life Science, College of Science, Rikkyo University, Toshima-ku, Tokyo, Japan
| | - Yasuyuki Kato-Yamada
- Department of Life Science, College of Science, Rikkyo University, Toshima-ku, Tokyo, Japan.,Research Center for Life Science, College of Science, Rikkyo University, Toshima-ku, Tokyo, Japan
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12
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Free lactic acid production under acidic conditions by lactic acid bacteria strains: challenges and future prospects. Appl Microbiol Biotechnol 2018; 102:5911-5924. [DOI: 10.1007/s00253-018-9092-4] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Revised: 05/10/2018] [Accepted: 05/10/2018] [Indexed: 11/27/2022]
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13
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Whitham JM, Moon JW, Rodriguez M, Engle NL, Klingeman DM, Rydzak T, Abel MM, Tschaplinski TJ, Guss AM, Brown SD. Clostridium thermocellum LL1210 pH homeostasis mechanisms informed by transcriptomics and metabolomics. BIOTECHNOLOGY FOR BIOFUELS 2018; 11:98. [PMID: 29632556 PMCID: PMC5887222 DOI: 10.1186/s13068-018-1095-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2017] [Accepted: 03/24/2018] [Indexed: 05/21/2023]
Abstract
BACKGROUND Clostridium (Ruminiclostridium) thermocellum is a model fermentative anaerobic thermophile being studied and engineered for consolidated bioprocessing of lignocellulosic feedstocks into fuels and chemicals. Engineering efforts have resulted in significant improvements in ethanol yields and titers although further advances are required to make the bacterium industry-ready. For instance, fermentations at lower pH could enable co-culturing with microbes that have lower pH optima, augment productivity, and reduce buffering cost. C. thermocellum is typically grown at neutral pH, and little is known about its pH limits or pH homeostasis mechanisms. To better understand C. thermocellum pH homeostasis we grew strain LL1210 (C. thermocellum DSM1313 Δhpt ΔhydG Δldh Δpfl Δpta-ack), currently the highest ethanol producing strain of C. thermocellum, at different pH values in chemostat culture and applied systems biology tools. RESULTS Clostridium thermocellum LL1210 was found to be growth-limited below pH 6.24 at a dilution rate of 0.1 h-1. F1F0-ATPase gene expression was upregulated while many ATP-utilizing enzymes and pathways were downregulated at pH 6.24. These included most flagella biosynthesis genes, genes for chemotaxis, and other motility-related genes (> 50) as well as sulfate transport and reduction, nitrate transport and nitrogen fixation, and fatty acid biosynthesis genes. Clustering and enrichment of differentially expressed genes at pH values 6.48, pH 6.24 and pH 6.12 (washout conditions) compared to pH 6.98 showed inverse differential expression patterns between the F1F0-ATPase and genes for other ATP-utilizing enzymes. At and below pH 6.24, amino acids including glutamate and valine; long-chain fatty acids, their iso-counterparts and glycerol conjugates; glycolysis intermediates 3-phosphoglycerate, glucose 6-phosphate, and glucose accumulated intracellularly. Glutamate was 267 times more abundant in cells at pH 6.24 compared to pH 6.98, and intercellular concentration reached 1.8 μmol/g pellet at pH 5.80 (stopped flow). CONCLUSIONS Clostridium thermocellum LL1210 can grow under slightly acidic conditions, similar to limits reported for other strains. This foundational study provides a detailed characterization of a relatively acid-intolerant bacterium and provides genetic targets for strain improvement. Future studies should examine adding gene functions used by more acid-tolerant bacteria for improved pH homeostasis at acidic pH values.
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Affiliation(s)
- Jason M. Whitham
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN USA
- BioEnergy Science Center, National Laboratory, Oak Ridge, TN USA
| | - Ji-Won Moon
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN USA
| | - Miguel Rodriguez
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN USA
- BioEnergy Science Center, National Laboratory, Oak Ridge, TN USA
| | - Nancy L. Engle
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN USA
- BioEnergy Science Center, National Laboratory, Oak Ridge, TN USA
| | - Dawn M. Klingeman
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN USA
- BioEnergy Science Center, National Laboratory, Oak Ridge, TN USA
| | - Thomas Rydzak
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN USA
- BioEnergy Science Center, National Laboratory, Oak Ridge, TN USA
- Present Address: Department of Biological Science, University of Calgary, Calgary, AB T2N 1N4 Canada
| | - Malaney M. Abel
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN USA
- BioEnergy Science Center, National Laboratory, Oak Ridge, TN USA
| | - Timothy J. Tschaplinski
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN USA
- BioEnergy Science Center, National Laboratory, Oak Ridge, TN USA
| | - Adam M. Guss
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN USA
- BioEnergy Science Center, National Laboratory, Oak Ridge, TN USA
| | - Steven D. Brown
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN USA
- BioEnergy Science Center, National Laboratory, Oak Ridge, TN USA
- Present Address: LanzaTech, Inc., Skokie, IL USA
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14
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Liu Z, He Z, Huang H, Ran X, Oluwafunmilayo AO, Lu Z. pH Stress-Induced Cooperation between Rhodococcus ruber YYL and Bacillus cereus MLY1 in Biodegradation of Tetrahydrofuran. Front Microbiol 2017; 8:2297. [PMID: 29209303 PMCID: PMC5702389 DOI: 10.3389/fmicb.2017.02297] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 11/07/2017] [Indexed: 11/28/2022] Open
Abstract
Microbial consortia consisting of cooperational strains exhibit biodegradation performance superior to that of single microbial strains and improved remediation efficiency by relieving the environmental stress. Tetrahydrofuran (THF), a universal solvent widely used in chemical and pharmaceutical synthesis, significantly affects the environment. As a refractory pollutant, THF can be degraded by some microbial strains under suitable conditions. There are often a variety of stresses, especially pH stress, that inhibit the THF-degradation efficiency of microbial consortia. Therefore, it is necessary to study the molecular mechanisms of microbial cooperational degradation of THF. In this study, under conditions of low pH (initial pH = 7.0) stress, a synergistic promotion of the THF degradation capability of the strain Rhodococcus ruber YYL was found in the presence of a non-THF degrading strain Bacillus cereus MLY1. Metatranscriptome analysis revealed that the low pH stress induced the strain YYL to up-regulate the genes involved in anti-oxidation, mutation, steroid and bile acid metabolism, and translation, while simultaneously down-regulating the genes involved in ATP production. In the co-culture system, strain MLY1 provides fatty acids, ATP, and amino acids for strain YYL in response to low pH stress during THF degradation. In return, YYL shares the metabolic intermediates of THF with MLY1 as carbon sources. This study provides the preliminary mechanism to understand how microbial consortia improve the degradation efficiency of refractory furan pollutants under environmental stress conditions.
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Affiliation(s)
- Zubi Liu
- College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Zhixing He
- College of Basic Medical Science, Zhejiang Chinese Medical University, Hangzhou, China
| | - Hui Huang
- College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Xuebin Ran
- College of Life Sciences, Zhejiang University, Hangzhou, China
| | | | - Zhenmei Lu
- College of Life Sciences, Zhejiang University, Hangzhou, China
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15
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Shabayek S, Spellerberg B. Acid Stress Response Mechanisms of Group B Streptococci. Front Cell Infect Microbiol 2017; 7:395. [PMID: 28936424 PMCID: PMC5594096 DOI: 10.3389/fcimb.2017.00395] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2017] [Accepted: 08/23/2017] [Indexed: 12/20/2022] Open
Abstract
Group B streptococcus (GBS) is a leading cause of neonatal mortality and morbidity in the United States and Europe. It is part of the vaginal microbiota in up to 30% of pregnant women and can be passed on to the newborn through perinatal transmission. GBS has the ability to survive in multiple different host niches. The pathophysiology of this bacterium reveals an outstanding ability to withstand varying pH fluctuations of the surrounding environments inside the human host. GBS host pathogen interations include colonization of the acidic vaginal mucosa, invasion of the neutral human blood or amniotic fluid, breaching of the blood brain barrier as well as survival within the acidic phagolysosomal compartment of macrophages. However, investigations on GBS responses to acid stress are limited. Technologies, such as whole genome sequencing, genome-wide transcription and proteome mapping facilitate large scale identification of genes and proteins. Mechanisms enabling GBS to cope with acid stress have mainly been studied through these techniques and are summarized in the current review
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Affiliation(s)
- Sarah Shabayek
- Institute of Medical Microbiology and Hygiene, University of UlmUlm, Germany.,Department of Microbiology and Immunology, Faculty of Pharmacy, Suez Canal UniversityIsmailia, Egypt
| | - Barbara Spellerberg
- Institute of Medical Microbiology and Hygiene, University of UlmUlm, Germany
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16
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Danchin A, Fang G. Unknown unknowns: essential genes in quest for function. Microb Biotechnol 2016; 9:530-40. [PMID: 27435445 PMCID: PMC4993169 DOI: 10.1111/1751-7915.12384] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Accepted: 06/24/2016] [Indexed: 01/18/2023] Open
Abstract
The experimental design of a minimal synthetic genome revealed the presence of a large number of genes without ascribed function, in part because the abstract laws of life must be implemented within ad hoc material contraptions. Creating a function needs recruitment of some pre‐existing structure and this reveals kludges in their set‐up and history. Here, we show that looking for functions as an engineer would help in discovery of a significant number of those, proposed together with conceptual handles allowing investigators to pursue this endeavour in other contexts.
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Affiliation(s)
- Antoine Danchin
- Institute of Cardiometabolism and Nutrition, CHU Pitié-Salpêtrière, 47 boulevard de l'Hôpital, 75013, Paris, France
| | - Gang Fang
- Department of Biology, New York University Shanghai Campus, 1555 Century Avenue, Pudong New Area, Shanghai, 200122, China
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17
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Zhang J, Liu J, Ling J, Tong Z, Fu Y, Liang M. Inactivation of glutamate racemase (MurI) eliminates virulence in Streptococcus mutans. Microbiol Res 2016; 186-187:1-8. [PMID: 27242137 DOI: 10.1016/j.micres.2016.02.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Revised: 02/04/2016] [Accepted: 02/08/2016] [Indexed: 10/22/2022]
Abstract
Inhibition of enzymes required for bacterial cell wall synthesis is often lethal or leads to virulence defects. Glutamate racemase (MurI), an essential enzyme in peptidoglycan biosynthesis, has been an attractive target for therapeutic interventions. Streptococcus mutans, one of the many etiological factors of dental caries, possesses a series of virulence factors associated with cariogenicity. However, little is known regarding the mechanism by which MurI influences pathogenesis of S. mutans. In this work, a stable mutant of S. mutans deficient in glutamate racemase (S. mutans FW1718) was constructed to investigate the impact of murI inactivation on cariogenic virulence in S. mutans UA159. Microscopy revealed that the murI mutant exhibited an enlarged cell size, longer cell chains, diminished cell⬜cell aggregation, and altered cell surface ultrastructure compared with the wild-type. Characterization of this mutant revealed that murI deficiency weakened acidogenicity, aciduricity, and biofilm formation ability of S. mutans (P<0.05). Real-time quantitative polymerase chain reaction (qRT-PCR) analysis demonstrated that the deletion of murI reduced the expression of the acidogenesis-related gene ldh by 44-fold (P<0.0001). The expression levels of the gene coding for surface protein antigen P (spaP) and the acid-tolerance related gene (atpD) were down-regulated by 99% (P<0.0001). Expression of comE, comD, gtfB and gtfC, genes related to biofilm formation, were down-regulated 8-, 43-, 85- and 298-fold in the murI mutant compared with the wild-type (P<0.0001), respectively. Taken together, the current study provides the first evidence that MurI deficiency adversely affects S. mutans virulence properties, making MurI a potential target for controlling dental caries.
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Affiliation(s)
- Jianying Zhang
- Guangdong Province Key Laboratory of Stomatology, Sun Yat-Sen University, 74 Zhong Shan ER Road, Guangzhou 510080, China; Department of Operative Dentistry and Endodontics, Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-Sen University, 56 Lingyuanxi Road, Guangzhou 510055, China
| | - Jia Liu
- Guangdong Province Key Laboratory of Stomatology, Sun Yat-Sen University, 74 Zhong Shan ER Road, Guangzhou 510080, China; Department of Operative Dentistry and Endodontics, Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-Sen University, 56 Lingyuanxi Road, Guangzhou 510055, China
| | - Junqi Ling
- Guangdong Province Key Laboratory of Stomatology, Sun Yat-Sen University, 74 Zhong Shan ER Road, Guangzhou 510080, China; Department of Operative Dentistry and Endodontics, Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-Sen University, 56 Lingyuanxi Road, Guangzhou 510055, China.
| | - Zhongchun Tong
- Department of Operative Dentistry and Endodontics, Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-Sen University, 56 Lingyuanxi Road, Guangzhou 510055, China
| | - Yun Fu
- Department of Periodontology, Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-Sen University, 56 Lingyuanxi Road, Guangzhou 510055, China
| | - Min Liang
- Department of Periodontology, Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-Sen University, 56 Lingyuanxi Road, Guangzhou 510055, China
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18
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Fingermann M, Hozbor D. Acid tolerance response of Bordetella bronchiseptica in avirulent phase. Microbiol Res 2015; 181:52-60. [DOI: 10.1016/j.micres.2015.09.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Revised: 08/26/2015] [Accepted: 09/01/2015] [Indexed: 01/06/2023]
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19
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Senouci-Rezkallah K, Jobin MP, Schmitt P. Adaptive responses of Bacillus cereus ATCC14579 cells upon exposure to acid conditions involve ATPase activity to maintain their internal pH. Microbiologyopen 2015; 4:313-322. [PMID: 25740257 PMCID: PMC4398511 DOI: 10.1002/mbo3.239] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Revised: 12/17/2014] [Accepted: 12/22/2014] [Indexed: 11/08/2022] Open
Abstract
This study examined the involvement of ATPase activity in the acid tolerance response (ATR) of Bacillus cereus ATCC14579 strain. In the current work, B. cereus cells were grown in anaerobic chemostat culture at external pH (pHe ) 7.0 or 5.5 and at a growth rate of 0.2 h-1 . Population reduction and internal pH (pHi ) after acid shock at pH 4.0 was examined either with or without ATPase inhibitor N,N'-dicyclohexylcarbodiimide (DCCD) and ionophores valinomycin and nigericin. Population reduction after acid shock at pH 4.0 was strongly limited in cells grown at pH 5.5 (acid-adapted cells) compared with cells grown at pH 7.0 (unadapted cells), indicating that B. cereus cells grown at low pHe were able to induce a significant ATR and Exercise-induced increase in ATPase activity. However, DCCD and ionophores had a negative effect on the ability of B. cereus cells to survive and maintain their pHi during acid shock. When acid shock was achieved after DCCD treatment, pHi was markedly dropped in unadapted and acid-adapted cells. The ATPase activity was also significantly inhibited by DCCD and ionophores in acid-adapted cells. Furthermore, transcriptional analysis revealed that atpB (ATP beta chain) transcripts was increased in acid-adapted cells compared to unadapted cells before and after acid shock. Our data demonstrate that B. cereus is able to induce an ATR during growth at low pH. These adaptations depend on the ATPase activity induction and pHi homeostasis. Our data demonstrate that the ATPase enzyme can be implicated in the cytoplasmic pH regulation and in acid tolerance of B. cereus acid-adapted cells.
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Affiliation(s)
- Khadidja Senouci-Rezkallah
- UMR408 Sécurité et Qualité des Produits d'Origine Végétale, INRA, Université d'Avignon, 84914, Avignon, France.,Faculté des Sciences de la Nature et de la Vie, Université de Mascara, Mascara, Algérie.,Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, Montréal, Québec, Canada
| | - Michel P Jobin
- UMR408 Sécurité et Qualité des Produits d'Origine Végétale, INRA, Université d'Avignon, 84914, Avignon, France
| | - Philippe Schmitt
- UMR408 Sécurité et Qualité des Produits d'Origine Végétale, INRA, Université d'Avignon, 84914, Avignon, France
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20
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Citrulline protects Streptococcus pyogenes from acid stress using the arginine deiminase pathway and the F1Fo-ATPase. J Bacteriol 2015; 197:1288-96. [PMID: 25645553 DOI: 10.1128/jb.02517-14] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
UNLABELLED A common stress encountered by both pathogenic and environmental bacteria is exposure to a low-pH environment, which can inhibit cell growth and lead to cell death. One major defense mechanism against this stress is the arginine deiminase (ADI) pathway, which catabolizes arginine to generate two ammonia molecules and one molecule of ATP. While this pathway typically relies on the utilization of arginine, citrulline has also been shown to enter into the pathway and contribute to protection against acid stress. In the pathogenic bacterium Streptococcus pyogenes, the utilization of citrulline has been demonstrated to contribute to pathogenesis in a murine model of soft tissue infection, although the mechanism underlying its role in infection is unknown. To gain insight into this question, we analyzed a panel of mutants defective in different steps in the ADI pathway to dissect how arginine and citrulline protect S. pyogenes in a low-pH environment. While protection provided by arginine utilization occurred through the buffering of the extracellular environment, citrulline catabolism protection was pH independent, requiring the generation of ATP via the ADI pathway and a functional F1Fo-ATP synthase. This work demonstrates that arginine and citrulline catabolism protect against acid stress through distinct mechanisms and have unique contributions to virulence during an infection. IMPORTANCE An important aspect of bacterial pathogenesis is the utilization of host-derived nutrients during an infection for growth and virulence. Previously published work from our lab identified a unique role for citrulline catabolism in Streptococcus pyogenes during a soft tissue infection. The present article probes the role of citrulline utilization during this infection and its contribution to protection against acid stress. This work reveals a unique and concerted action between the catabolism of citrulline and the F1Fo-ATPase that function together to provide protection for bacteria in a low-pH environment. Dissection of these collaborative pathways highlights the complexity of bacterial infections and the contribution of atypical nutrients, such as citrulline, to pathogenesis.
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21
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In vitro manganese-dependent cross-talk between Streptococcus mutans VicK and GcrR: implications for overlapping stress response pathways. PLoS One 2014; 9:e115975. [PMID: 25536343 PMCID: PMC4275253 DOI: 10.1371/journal.pone.0115975] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Accepted: 12/03/2014] [Indexed: 11/19/2022] Open
Abstract
Streptococcus mutans, a major acidogenic component of the dental plaque biofilm, has a key role in caries etiology. Previously, we demonstrated that the VicRK two-component signal transduction system modulates biofilm formation, oxidative stress and acid tolerance responses in S. mutans. Using in vitro phosphorylation assays, here we demonstrate for the first time, that in addition to activating its cognate response regulator protein, the sensor kinase, VicK can transphosphorylate a non-cognate stress regulatory response regulator, GcrR, in the presence of manganese. Manganese is an important micronutrient that has been previously correlated with caries incidence, and which serves as an effector of SloR-mediated metalloregulation in S. mutans. Our findings supporting regulatory effects of manganese on the VicRK, GcrR and SloR, and the cross-regulatory networks formed by these components are more complex than previously appreciated. Using DNaseI footprinting we observed overlapping DNA binding specificities for VicR and GcrR in native promoters, consistent with these proteins being part of the same transcriptional regulon. Our results also support a role for SloR as a positive regulator of the vicRK two component signaling system, since its transcription was drastically reduced in a SloR-deficient mutant. These findings demonstrate the regulatory complexities observed with the S. mutans manganese-dependent response, which involves cross-talk between non-cognate signal transduction systems (VicRK and GcrR) to modulate stress response pathways.
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22
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Lund P, Tramonti A, De Biase D. Coping with low pH: molecular strategies in neutralophilic bacteria. FEMS Microbiol Rev 2014; 38:1091-125. [PMID: 24898062 DOI: 10.1111/1574-6976.12076] [Citation(s) in RCA: 282] [Impact Index Per Article: 28.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Revised: 02/26/2014] [Accepted: 03/14/2014] [Indexed: 12/31/2022] Open
Abstract
As part of their life cycle, neutralophilic bacteria are often exposed to varying environmental stresses, among which fluctuations in pH are the most frequent. In particular, acid environments can be encountered in many situations from fermented food to the gastric compartment of the animal host. Herein, we review the current knowledge of the molecular mechanisms adopted by a range of Gram-positive and Gram-negative bacteria, mostly those affecting human health, for coping with acid stress. Because organic and inorganic acids have deleterious effects on the activity of the biological macromolecules to the point of significantly reducing growth and even threatening their viability, it is not unexpected that neutralophilic bacteria have evolved a number of different protective mechanisms, which provide them with an advantage in otherwise life-threatening conditions. The overall logic of these is to protect the cell from the deleterious effects of a harmful level of protons. Among the most favoured mechanisms are the pumping out of protons, production of ammonia and proton-consuming decarboxylation reactions, as well as modifications of the lipid content in the membrane. Several examples are provided to describe mechanisms adopted to sense the external acidic pH. Particular attention is paid to Escherichia coli extreme acid resistance mechanisms, the activity of which ensure survival and may be directly linked to virulence.
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Affiliation(s)
- Peter Lund
- School of Biosciences, University of Birmingham, Birmingham, UK
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23
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Simcikova M, Prather KL, Prazeres DM, Monteiro GA. On the dual effect of glucose during production of pBAD/AraC-based minicircles. Vaccine 2014; 32:2843-6. [DOI: 10.1016/j.vaccine.2014.02.035] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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24
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Hasan S, Singh K, Danisuddin M, Verma PK, Khan AU. Inhibition of major virulence pathways of Streptococcus mutans by quercitrin and deoxynojirimycin: a synergistic approach of infection control. PLoS One 2014; 9:e91736. [PMID: 24622055 PMCID: PMC3951425 DOI: 10.1371/journal.pone.0091736] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Accepted: 02/13/2014] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVES To evaluate the synergistic effect of Quercitrin and Deoxynojirimycin (DNJ) together with their individual inhibitory effect against virulence pathways of Streptococcus mutans. METHODOLOGY MICs of both the compounds were determined by the microdilution method, followed by their in vitrosynergy using checkerboard and time kill assay. The nature of interaction was classified as synergistic on the basis of fractional inhibitory concentration index (FICI) value of ≤0.5. Furthermore, the activity of Quercitrin and DNJ was evaluated individually and in combination against various cariogenic properties of S. mutans UA159 such as acidogenesis, aciduracity, glucan production, hydrophobicity, biofilm and adherence. Moreover, expression of virulent genes in S. mutans was analysed by quantitative RT- PCR (qRT-PCR) and inhibition of F1F0-ATPase, lactate dehydrogenase and enolase was also evaluated. Finally, scanning electron microscopy (SEM) was used to investigate structural obliteration of biofilm. RESULTS The in vitro synergism between Quercitrin and DNJ was observed, with a FICI of 0.313. Their MIC values were found to be 64 μg/ml and 16 μg/ml respectively. The synergistic combination consistently showed best activity against all the virulence factors as compared to Quercitrin and DNJ individually. A reduction in glucan synthesis and biofilm formation was observed at different phases of growth. The qRT-PCR revealed significant downregulation of various virulent genes. Electron micrographs depicted the obliteration of biofilm as compared to control and the activity of cariogenic enzymes was also inhibited. CONCLUSIONS The whole study reflects a prospective role of Quercitrin and DNJ in combination as a potent anticariogenic agent against S. mutans.
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Affiliation(s)
- Sadaf Hasan
- Medical Microbiology and Molecular Biology Lab, Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh, India
| | - Kunal Singh
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, India
| | - Mohd Danisuddin
- Medical Microbiology and Molecular Biology Lab, Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh, India
| | - Praveen K. Verma
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, India
| | - Asad U. Khan
- Medical Microbiology and Molecular Biology Lab, Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh, India
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25
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Quinn HJ, Cameron ADS, Dorman CJ. Bacterial regulon evolution: distinct responses and roles for the identical OmpR proteins of Salmonella Typhimurium and Escherichia coli in the acid stress response. PLoS Genet 2014; 10:e1004215. [PMID: 24603618 PMCID: PMC3945435 DOI: 10.1371/journal.pgen.1004215] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Accepted: 01/16/2014] [Indexed: 12/26/2022] Open
Abstract
The evolution of new gene networks is a primary source of genetic innovation that allows bacteria to explore and exploit new niches, including pathogenic interactions with host organisms. For example, the archetypal DNA binding protein, OmpR, is identical between Salmonella Typhimurium serovar Typhimurium and Escherichia coli, but regulatory specialization has resulted in different environmental triggers of OmpR expression and largely divergent OmpR regulons. Specifically, ompR mRNA and OmpR protein levels are elevated by acid pH in S. Typhimurium but not in E. coli. This differential expression pattern is due to differences in the promoter regions of the ompR genes and the E. coli ompR orthologue can be made acid-inducible by introduction of the appropriate sequences from S. Typhimurium. The OmpR regulon in S. Typhimurium overlaps that of E. coli at only 15 genes and includes many horizontally acquired genes (including virulence genes) that E. coli does not have. We found that OmpR binds to its genomic targets in higher abundance when the DNA is relaxed, something that occurs in S. Typhimurium as a result of acid stress and which is a requirement for optimal expression of its virulence genes. The genomic targets of OmpR do not share a strong nucleotide sequence consensus: we propose that the ability of OmpR to recruit additional genes to its regulon arises from its modest requirements for specificity in its DNA targets with its preference for relaxed DNA allowing it to cooperate with DNA-topology-based allostery to modulate transcription in response to acid stress.
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Affiliation(s)
- Heather J. Quinn
- Department of Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin, Ireland
| | - Andrew D. S. Cameron
- Department of Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin, Ireland
- Department of Biology, University of Regina, Regina, Saskatchewan, Canada
| | - Charles J. Dorman
- Department of Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin, Ireland
- * E-mail:
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26
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Liu J, Ling JQ, Zhang K, Wu CD. Physiological properties of Streptococcus mutans UA159 biofilm-detached cells. FEMS Microbiol Lett 2013; 340:11-8. [PMID: 23278289 DOI: 10.1111/1574-6968.12066] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Revised: 12/11/2012] [Accepted: 12/13/2012] [Indexed: 01/09/2023] Open
Abstract
Biofilm detachment is a physiologically regulated process that facilitates the release of cells to colonize new sites and cause infections. Streptococcus mutans is one of the major inhabitants of cariogenic dental plaque biofilm. This study tested the hypothesis that S. mutans biofilm-detached cells exhibit distinct physiological properties compared with their sessile and planktonic counterparts. Biofilm-detached cells showed a longer generation time of 2.85 h compared with planktonic cells (2.06 h), but had higher phosphotransferase activity for sucrose and mannose (P < 0.05). Compared with planktonic cells, they showed higher chlorhexidine (CHX) resistance and fourfold more adherent (P < 0.05). Increased mutacin IV production in biofilm-detached cells was noted by a larger inhibition zone against Streptococcus gordonii (31.07 ± 1.62 mm vs. 25.2 ± 1.74 mm by planktonic cells; P < 0.05). The expressions of genes associated with biofilm formation (gtfC and comDE) and mutacin (nlmA) were higher compared with planktonic cells (P < 0.05). In many properties, biofilm-detached cells shared similarity with sessile cells except for a higher phosphotransferase activity for sucrose, glucose, and mannose, increased resistance to CHX, and elevated expression of gtfC-, comDE-, and acidurity-related gene aptD (P < 0.05). Based on data obtained, the S. mutans biofilm-detached cells are partially distinct in various physiological properties compared with their planktonic and sessile counterparts.
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Affiliation(s)
- Jia Liu
- Institute of Stomatological Research, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, China
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Nyanga-Koumou AP, Ouoba LII, Kobawila SC, Louembe D. Response mechanisms of lactic acid bacteria to alkaline environments: a review. Crit Rev Microbiol 2011; 38:185-90. [PMID: 22168378 DOI: 10.3109/1040841x.2011.640978] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Regulation of the cytoplasmic or internal pH (pHin) is a fundamental requirement for the survival and viability of bacteria. The optimum pHin for most bacteria is near the neutral point (pH 7.0). Therefore, bacteria may have some strategies to adapt themselves to the acidity or alkalinity of cytoplasm. As other microorganisms, lactic acid bacteria (LAB) are able to maintain a neutral or near neutral cytoplasmic pH even when the pH of the external medium varies. Mechanisms facilitating survival and growth under alkaline conditions of LAB are reviewed. These mechanisms are: (i) the active potassium extrusion and the potassium-proton antiport system, (ii) the sodium-proton antiport system, (iii) the proton-translocating adenosine triphosphatase (ATPase), (iv) the formation of transmembrane proton gradients (ΔpH) in a reversed direction, and (v) the adaptation, cross-protection, and changes in protein synthesis.
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Affiliation(s)
- Armand P Nyanga-Koumou
- Département de Biologie Cellulaire et Moléculaire, Faculté des Sciences, Université Marien N'Gouabi, Brazzaville, Congo
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Duary RK, Batish VK, Grover S. Relative gene expression of bile salt hydrolase and surface proteins in two putative indigenous Lactobacillus plantarum strains under in vitro gut conditions. Mol Biol Rep 2011; 39:2541-52. [PMID: 21674190 DOI: 10.1007/s11033-011-1006-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2011] [Accepted: 06/02/2011] [Indexed: 12/25/2022]
Abstract
Probiotic bacteria must overcome the toxicity of bile salts secreted in the gut and adhere to the epithelial cells to enable their better colonization with extended transit time. Expression of bile salt hydrolase and other proteins on the surface of probiotic bacteria can help in better survivability and optimal functionality in the gut. Two putative Lactobacillus plantarum isolates i.e., Lp9 and Lp91 along with standard strain CSCC5276 were used. A battery of six housekeeping genes viz. gapB, dnaG, gyrA, ldhD, rpoD and 16S rRNA were evaluated by using geNorm 3.4 excel based application for normalizing the expression of bile salt hydrolase (bsh), mucus-binding protein (mub), mucus adhesion promoting protein (mapA), and elongation factor thermo unstable (EF-Tu) in Lp9 and Lp91. The maximal level of relative bsh gene expression was recorded in Lp91 with 2.89 ± 0.14, 4.57 ± 0.37 and 6.38 ± 0.19 fold increase at 2% bile salt concentration after 1, 2 and 3 h, respectively. Similarly, mub and mapA genes were maximally expressed in Lp9 at the level of 20.07 ± 1.28 and 30.92 ± 1.51 fold, when MRS was supplemented with 0.05% mucin and 1% each of bile and pancreatin (pH 6.5). However, in case of EF-Tu, the maximal expression of 42.84 ± 5.64 fold was recorded in Lp91 in the presence of mucin alone (0.05%). Hence, the expression of bsh, mub, mapA and EF-Tu could be considered as prospective biomarkers for screening of novel probiotic lactobacillus strains for optimal functionality in the gut.
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Affiliation(s)
- Raj Kumar Duary
- Department of Food Processing and Technology, Tezpur University, Napaam, Assam 784028, India
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Abstract
Diverse mechanisms for pH sensing and cytoplasmic pH homeostasis enable most bacteria to tolerate or grow at external pH values that are outside the cytoplasmic pH range they must maintain for growth. The most extreme cases are exemplified by the extremophiles that inhabit environments with a pH of below 3 or above 11. Here, we describe how recent insights into the structure and function of key molecules and their regulators reveal novel strategies of bacterial pH homeostasis. These insights may help us to target certain pathogens more accurately and to harness the capacities of environmental bacteria more efficiently.
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Affiliation(s)
- Terry A. Krulwich
- Department of Pharmacology and Systems Therapeutics, Mount Sinai School of Medicine, Box 1603, 1 Gustave L. Levy Place, New York, NY 10029, USA; Tel. 212-241-7280; Fax. 212-996-7214
| | - George Sachs
- Departments of Physiology and Medicine, David Geffen School of Medicine at UCLA, 405 Hilgard Ave., Los Angeles, California 90024, USA Tel. 310-268-3923, Fax 310-312-9478
| | - Etana Padan
- Alexander Silberman Institute of Life Sciences, Hebrew University, Jerusalem 91904, Israel, Tel. 972 2 6585094, Fax 972 2 658947
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Jiang L, Wang J, Liang S, Cai J, Xu Z, Cen P, Yang S, Li S. Enhanced butyric acid tolerance and bioproduction by Clostridium tyrobutyricum immobilized in a fibrous bed bioreactor. Biotechnol Bioeng 2011; 108:31-40. [PMID: 20824675 DOI: 10.1002/bit.22927] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Repeated fed-batch fermentation of glucose by Clostridium tyrobutyricum immobilized in a fibrous bed bioreactor (FBB) was successfully employed to produce butyric acid at a high final concentration as well as to adapt a butyric-acid-tolerant strain. At the end of the eighth fed-batch fermentation, the butyric acid concentration reached 86.9 ± 2.17 g/L, which to our knowledge is the highest butyric acid concentration ever produced in the traditional fermentation process. To understand the mechanism and factors contributing to the improved butyric acid production and enhanced acid tolerance, adapted strains were harvested from the FBB and characterized for their physiological properties, including specific growth rate, acid-forming enzymes, intracellular pH, membrane-bound ATPase and cell morphology. Compared with the original culture used to seed the bioreactor, the adapted culture showed significantly reduced inhibition effects of butyric acid on specific growth rate, cellular activities of butyric-acid-forming enzyme phosphotransbutyrylase (PTB) and ATPase, together with elevated intracellular pH, and elongated rod morphology.
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Affiliation(s)
- Ling Jiang
- School of Bioscience and Bioengineering, South China University of Technology, Guangzhou 510640, PR China
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The tea catechin epigallocatechin gallate suppresses cariogenic virulence factors of Streptococcus mutans. Antimicrob Agents Chemother 2010; 55:1229-36. [PMID: 21149622 DOI: 10.1128/aac.01016-10] [Citation(s) in RCA: 214] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Streptococcus mutans, the primary etiologic agent of dental caries, possesses a series of virulence factors associated with its cariogenicity. Alternatives to traditional antimicrobial treatment, agents selectively inhibiting the virulence factors without necessarily suppressing the resident oral species, are promising. The anticariogenic properties of tea have been suggested in experimental animals and humans. Tea polyphenols, especially epigallocatechin gallate (EGCg), have been shown to inhibit the growth and glucosyltransferases activity of S. mutans. However, their effects on biofilm and cariogenic virulence factors of oral streptococci other than glucosyltransferases have not been well documented. In this study, we investigated the biological effect of EGCg on the virulence factors of S. mutans associated with its acidogenicity and acidurity. The antimicrobial effects of EGCg on S. mutans biofilm grown in chemically defined medium were also examined. EGCg inhibited growth of S. mutans planktonic cells at an MIC of 31.25 μg/ml and a minimal bactericidal concentration (MBC) of 62.5 μg/ml. EGCg also inhibited S. mutans biofilm formation at 15.6 μg/ml (minimum concentration that showed at least 90% inhibition of biofilm formation) and reduced viability of the preformed biofilm at 625 μg/ml (sessile MIC₈₀). EGCg at sub-MIC levels inhibited acidogenicity and acidurity of S. mutans cells. Analysis of the data obtained from real-time PCR showed that EGCg significantly suppressed the ldh, eno, atpD, and aguD genes of S. mutans UA159. Inhibition of the enzymatic activity of F₁F₀-ATPase and lactate dehydrogenase was also noted (50% inhibitory concentration between 15.6 and 31.25 μg/ml). These findings suggest that EGCg is a natural anticariogenic agent in that it exhibits antimicrobial activity against S. mutans and suppresses the specific virulence factors associated with its cariogenicity.
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F1F0-ATP synthases of alkaliphilic bacteria: lessons from their adaptations. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1797:1362-77. [PMID: 20193659 DOI: 10.1016/j.bbabio.2010.02.028] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2010] [Revised: 02/22/2010] [Accepted: 02/23/2010] [Indexed: 12/14/2022]
Abstract
This review focuses on the ATP synthases of alkaliphilic bacteria and, in particular, those that successfully overcome the bioenergetic challenges of achieving robust H+-coupled ATP synthesis at external pH values>10. At such pH values the protonmotive force, which is posited to provide the energetic driving force for ATP synthesis, is too low to account for the ATP synthesis observed. The protonmotive force is lowered at a very high pH by the need to maintain a cytoplasmic pH well below the pH outside, which results in an energetically adverse pH gradient. Several anticipated solutions to this bioenergetic conundrum have been ruled out. Although the transmembrane sodium motive force is high under alkaline conditions, respiratory alkaliphilic bacteria do not use Na+- instead of H+-coupled ATP synthases. Nor do they offset the adverse pH gradient with a compensatory increase in the transmembrane electrical potential component of the protonmotive force. Moreover, studies of ATP synthase rotors indicate that alkaliphiles cannot fully resolve the energetic problem by using an ATP synthase with a large number of c-subunits in the synthase rotor ring. Increased attention now focuses on delocalized gradients near the membrane surface and H+ transfers to ATP synthases via membrane-associated microcircuits between the H+ pumping complexes and synthases. Microcircuits likely depend upon proximity of pumps and synthases, specific membrane properties and specific adaptations of the participating enzyme complexes. ATP synthesis in alkaliphiles depends upon alkaliphile-specific adaptations of the ATP synthase and there is also evidence for alkaliphile-specific adaptations of respiratory chain components.
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Assinder SJ. Effects of pH and Acid End-Products on Acid Production in Oral Streptococci. MICROBIAL ECOLOGY IN HEALTH AND DISEASE 2009. [DOI: 10.3109/08910609509140088] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- S. J. Assinder
- MRC Dental Group, Dental School, Lower Maudlin Street, Bristol, BS1 2LY, UK
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A comparative proteomic analysis of Gluconacetobacter diazotrophicus PAL5 at exponential and stationary phases of cultures in the presence of high and low levels of inorganic nitrogen compound. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2008; 1784:1578-89. [PMID: 18662807 DOI: 10.1016/j.bbapap.2008.06.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2008] [Revised: 06/07/2008] [Accepted: 06/23/2008] [Indexed: 11/23/2022]
Abstract
A proteomic view of G. diazotrophicus PAL5 at the exponential (E) and stationary phases (S) of cultures in the presence of low (L) and high levels (H) of combined nitrogen is presented. The proteomes analyzed on 2D-gels showed 131 proteins (42E+32S+29H+28L) differentially expressed by G. diazotrophicus, from which 46 were identified by combining mass spectrometry and bioinformatics tools. Proteins related to cofactor, energy and DNA metabolisms and cytoplasmic pH homeostasis were differentially expressed in E growth phase, under L and H conditions, in line with the high metabolic rate of the cells and the low pH of the media. Proteins most abundant in S-phase cells were stress associated and transporters plus transferases in agreement with the general phenomenon that binding protein-dependent systems are induced under nutrient limitation as part of hunger response. Cells grown in L condition produced nitrogen-fixation accessory proteins with roles in biosynthesis and stabilization of the nitrogenase complex plus proteins for protection of the nitrogenases from O(2)-induced inactivation. Proteins of the cell wall biogenesis apparatus were also expressed under nitrogen limitation and might function in the reshaping of the nitrogen-fixing G. diazotrophicus cells previously described. Genes whose protein products were detected in our analysis were mapped onto the chromosome and, based on the tendency of functionally related bacterial genes to cluster, we identified genes of particular pathways that could be organized in operons and are co-regulated. These results showed the great potential of proteomics to describe events in G. diazotrophicus cells by looking at proteins expressed under distinct growth conditions.
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Chaia AP, de Saad A, de Ruiz Holgado AP, Oliver G. Influence of propionate on growth and fermentative activity of lactobacilli. ACTA ACUST UNITED AC 2008. [DOI: 10.1111/j.1365-2672.1994.tb03056.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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36
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Chaia AP, Strasser de Saad AM, de Ruiz Holgado AAP, Oliver G. Proton-ATPase activity in cells of lactobacilli grown in the presence of propionate. ACTA ACUST UNITED AC 2008. [DOI: 10.1111/j.1365-2672.1994.tb03041.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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37
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Molecular cloning and characterisation of gamma subunit of H+-ATPase inLactobacillus acidophilus MG2-9. ANN MICROBIOL 2007. [DOI: 10.1007/bf03175082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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38
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Hasona A, Zuobi-Hasona K, Crowley PJ, Abranches J, Ruelf MA, Bleiweis AS, Brady LJ. Membrane composition changes and physiological adaptation by Streptococcus mutans signal recognition particle pathway mutants. J Bacteriol 2006; 189:1219-30. [PMID: 17085548 PMCID: PMC1797365 DOI: 10.1128/jb.01146-06] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Previously, we presented evidence that the oral cariogenic species Streptococcus mutans remains viable but physiologically impaired and sensitive to environmental stress when genes encoding the minimal conserved bacterial signal recognition particle (SRP) elements are inactivated. Two-dimensional gel electrophoresis of isolated membrane fractions from strain UA159 and three mutants (Deltaffh, DeltascRNA, and DeltaftsY) grown at pH 7.0 or pH 5.0 allowed us to obtain insight into the adaptation process and the identities of potential SRP substrates. Mutant membrane preparations contained increased amounts of the chaperones DnaK and GroES and ClpP protease but decreased amounts of transcription- and translation-related proteins, the beta subunit of ATPase, HPr, and several metabolic and glycolytic enzymes. Therefore, the acid sensitivity of SRP mutants might be caused in part by diminished ATPase activity, as well as the absence of an efficient mechanism for supplying ATP quickly at the site of proton elimination. Decreased amounts of LuxS were also observed in all mutant membranes. To further define physiological changes that occur upon disruption of the SRP pathway, we studied global gene expression in S. mutans UA159 (parent strain) and AH333 (Deltaffh mutant) using microarray analysis. Transcriptome analysis revealed up-regulation of 81 genes, including genes encoding chaperones, proteases, cell envelope biosynthetic enzymes, and DNA repair and replication enzymes, and down-regulation of 35 genes, including genes concerned with competence, ribosomal proteins, and enzymes involved in amino acid and protein biosynthesis. Quantitative real-time reverse transcription-PCR analysis of eight selected genes confirmed the microarray data. Consistent with a demonstrated defect in competence and the suggested impairment of LuxS-dependent quorum sensing, biofilm formation was significantly decreased in each SRP mutant.
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Affiliation(s)
- Adnan Hasona
- Department of Oral Biology, University of Florida, Gainesville, FL 32610, USA.
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39
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Penaud S, Fernandez A, Boudebbouze S, Ehrlich SD, Maguin E, van de Guchte M. Induction of heavy-metal-transporting CPX-type ATPases during acid adaptation in Lactobacillus bulgaricus. Appl Environ Microbiol 2006; 72:7445-54. [PMID: 16997986 PMCID: PMC1694267 DOI: 10.1128/aem.01109-06] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Lactobacillus bulgaricus is a lactic acid bacteria (LAB) that, through the production of lactic acid, gradually acidifies its environment during growth. In the course of this process, L. bulgaricus acquires an improved tolerance to acidity. A survey of the recently established genome sequence shows that this bacterium possesses few of the pH control functions that have been described in other LAB and raises the question of what other mechanisms could be involved in its adaptation to the decreasing environmental pH. In some bacteria other than LAB, ion transport systems have been implicated in acid adaptation. We therefore studied the expression of this type of transport system during acid adaptation in L. bulgaricus by reverse transcription and real-time quantitative PCR and mapped transcription start sites. Intriguingly, the most significantly induced were three ATPases carrying the CPX signature of heavy-metal transporters. Protein homology and the presence of a conserved sequence motif in the promoter regions of the genes encoding these proteins strongly suggest that they are involved in copper homeostasis. Induction of this system is thought to assist in avoiding indirect damage that could result from medium acidification.
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Affiliation(s)
- S Penaud
- Génétique Microbienne, INRA-CRJ, 78352 Jouy en Josas cedex, France
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40
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Shabala L, Ross T, McMeekin T, Shabala S. Non-invasive microelectrode ion flux measurements to study adaptive responses of microorganisms to the environment. FEMS Microbiol Rev 2006; 30:472-86. [PMID: 16594966 DOI: 10.1111/j.1574-6976.2006.00019.x] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The regulation of membrane-transport activity is crucial for intracellular pH homeostasis, maintenance of cell osmotic potential, nutrient acquisition, signalling, and adaptation of bacterial cells. The non-invasive microelectrode ion flux estimation (MIFE) technique is a powerful tool for kinetic studies of membrane-transport processes across cellular membranes. Since 2001, when this technique was first applied to the study of membrane-transport processes in bacterial cells (J Microbiol Methods 46, 119-129), a large amount of information has been accumulated. This review summarizes some of these findings and discusses the advantages and applicability of this technique in studying bacterial adaptive responses to adverse environmental conditions. First, various methodological aspects of the application of this novel technique in microbiology are discussed. Then, several practical examples ('case studies') are described. The latter include changes in membrane-transport activity in response to various stresses (acidic, osmotic, and temperature stresses) as well as flux changes as a function of bacterial growth stage and nutrient availability. It is shown that non-invasive ion flux measurements may provide a significant conceptual advance in our understanding of adaptive responses in bacteria, fungi and biofilms to a variety of environmental conditions. The technique can also be used for the rapid assessment of food-processing treatments aimed at reducing bacterial contamination of food and for the development of strategies to assess the resistance of organisms to antimicrobial agents.
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Affiliation(s)
- Lana Shabala
- Australian Food Safety Centre of Excellence, University of Tasmania, Hobart, Tasmania, Australia.
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Martín-Galiano AJ, Overweg K, Ferrándiz MJ, Reuter M, Wells JM, de la Campa AG. Transcriptional analysis of the acid tolerance response in Streptococcus pneumoniae. Microbiology (Reading) 2005; 151:3935-3946. [PMID: 16339938 DOI: 10.1099/mic.0.28238-0] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Streptococcus pneumoniae, one of the major causes of morbidity and mortality in humans, faces a range of potentially acidic conditions in the middle and late stages of growthin vitro, in diverse human fluids during the infection process, and in biofilms present in the nasopharynx of carriers.S. pneumoniaewas shown to develop a weak acid tolerance response (ATR), where cells previously exposed to sublethal pHs (5·8–6·6) showed an increased survival rate of up to one order of magnitude after challenge at the lethal pH (4·4, survival rate of 10−4). Moreover, the survival after challenge of stationary phase cells at pH 4·4 was three orders of magnitude higher than that of cells taken from the exponential phase, due to the production of lactic acid during growth and increasing acidification of the growth medium until stationary phase. Global expression analysis after short-term (5, 15 and 30 min, the adaptation phase) and long-term (the maintenance phase) acidic shock (pH 6·0) was performed by microarray experiments, and the results were validated by real-time RT-PCR. Out of a total of 126 genes responding to acidification, 59 and 37 were specific to the adaptation phase and maintenance phase, respectively, and 30 were common to both periods. In the adaptation phase, both up- and down-regulation of gene transcripts was observed (38 and 21 genes, respectively), whereas in the maintenance phase most of the affected genes were down-regulated (34 out of 37). Genes involved in protein fate (including those involved in the protection of the protein native structure) and transport (including transporters of manganese and iron) were overrepresented among the genes affected by acidification, 8·7 and 24·6 % of the acid-responsive genes compared to 2·8 % and 9·6 % of the genome complement, respectively. Cross-regulation with the response to oxidative and osmotic stress was observed. Potential regulatory motifs involved in the ATR were identified in the promoter regions of some of the regulated genes.
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Affiliation(s)
- Antonio J Martín-Galiano
- Unidad de Genética Bacteriana, Centro Nacional de Microbiología, Instituto de Salud Carlos III, 28220, Majadahonda, Madrid, Spain
| | - Karin Overweg
- Bacterial Infection and Immunity Group, Institute of Food Research, Norwich Research Park, Norwich NR4 7UA, UK
| | - Maria J Ferrándiz
- Unidad de Genética Bacteriana, Centro Nacional de Microbiología, Instituto de Salud Carlos III, 28220, Majadahonda, Madrid, Spain
| | - Mark Reuter
- Bacterial Infection and Immunity Group, Institute of Food Research, Norwich Research Park, Norwich NR4 7UA, UK
| | - Jerry M Wells
- Bacterial Infection and Immunity Group, Institute of Food Research, Norwich Research Park, Norwich NR4 7UA, UK
| | - Adela G de la Campa
- Unidad de Genética Bacteriana, Centro Nacional de Microbiología, Instituto de Salud Carlos III, 28220, Majadahonda, Madrid, Spain
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Padan E, Bibi E, Ito M, Krulwich TA. Alkaline pH homeostasis in bacteria: new insights. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2005; 1717:67-88. [PMID: 16277975 PMCID: PMC3072713 DOI: 10.1016/j.bbamem.2005.09.010] [Citation(s) in RCA: 484] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2005] [Revised: 08/19/2005] [Accepted: 09/07/2005] [Indexed: 10/25/2022]
Abstract
The capacity of bacteria to survive and grow at alkaline pH values is of widespread importance in the epidemiology of pathogenic bacteria, in remediation and industrial settings, as well as in marine, plant-associated and extremely alkaline ecological niches. Alkali-tolerance and alkaliphily, in turn, strongly depend upon mechanisms for alkaline pH homeostasis, as shown in pH shift experiments and growth experiments in chemostats at different external pH values. Transcriptome and proteome analyses have recently complemented physiological and genetic studies, revealing numerous adaptations that contribute to alkaline pH homeostasis. These include elevated levels of transporters and enzymes that promote proton capture and retention (e.g., the ATP synthase and monovalent cation/proton antiporters), metabolic changes that lead to increased acid production, and changes in the cell surface layers that contribute to cytoplasmic proton retention. Targeted studies over the past decade have followed up the long-recognized importance of monovalent cations in active pH homeostasis. These studies show the centrality of monovalent cation/proton antiporters in this process while microbial genomics provides information about the constellation of such antiporters in individual strains. A comprehensive phylogenetic analysis of both eukaryotic and prokaryotic genome databases has identified orthologs from bacteria to humans that allow better understanding of the specific functions and physiological roles of the antiporters. Detailed information about the properties of multiple antiporters in individual strains is starting to explain how specific monovalent cation/proton antiporters play dominant roles in alkaline pH homeostasis in cells that have several additional antiporters catalyzing ostensibly similar reactions. New insights into the pH-dependent Na(+)/H(+) antiporter NhaA that plays an important role in Escherichia coli have recently emerged from the determination of the structure of NhaA. This review highlights the approaches, major findings and unresolved problems in alkaline pH homeostasis, focusing on the small number of well-characterized alkali-tolerant and extremely alkaliphilic bacteria.
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Affiliation(s)
- Etana Padan
- Alexander Silberman Institute of Life Sciences, Hebrew University, Jerusalem 91904, Israel.
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Sauer U, Schlattner U. Inverse metabolic engineering with phosphagen kinase systems improves the cellular energy state. Metab Eng 2005; 6:220-8. [PMID: 15256212 DOI: 10.1016/j.ymben.2003.11.004] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2003] [Accepted: 11/13/2003] [Indexed: 11/23/2022]
Abstract
Inverse metabolic engineering attempts to identify or construct desired phenotypes of applied interest to endow them on appropriate host organisms. A particular desirable phenotype is the ATP homeostasis exhibited by animal cells with high and variable ATP turnover through temporal and spatial energy buffering. This buffering is achieved by phosphagen kinase systems that consist of a specific kinase and its cognate phosphagen, which functions as a large pool of 'high-energy phosphates' that are used to replenish ATP during periods of high energetic demand. This review discusses recent advances and potentials of inverse metabolic engineering of cell types that do not normally contain such systems--bacteria, yeast, plants, and liver--with creatine or arginine kinase systems. Examples are discussed that illustrate how microbial metabolism can be tailored for large-scale industrial processes with imperfect mixing and how the liver can be protected from metabolic insults or stimulated for better regeneration.
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Affiliation(s)
- Uwe Sauer
- Institute of Biotechnology, Swiss Federal Institute of Technology (ETH) Zürich, CH-8093.
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Kuhnert WL, Zheng G, Faustoferri RC, Quivey RG. The F-ATPase operon promoter of Streptococcus mutans is transcriptionally regulated in response to external pH. J Bacteriol 2004; 186:8524-8. [PMID: 15576803 PMCID: PMC532412 DOI: 10.1128/jb.186.24.8524-8528.2004] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2004] [Accepted: 09/15/2004] [Indexed: 11/20/2022] Open
Abstract
Streptococcus mutans F-ATPase, the major component of the acid-adaptive response of the organism, is transcriptionally upregulated at low pH. Fusions of the F-ATPase promoter to chloramphenicol acetyltransferase indicated that pH-dependent expression is still observed with a short promoter that contains a domain conserved between streptococcal ATPase operons.
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Affiliation(s)
- Wendi L Kuhnert
- Center for Oral Biology, Box 611, 601 Elmwood Ave., Rochester, NY 14642, USA
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45
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Crowley PJ, Svensäter G, Snoep JL, Bleiweis AS, Brady L. Anffhmutant ofStreptococcus mutansis viable and able to physiologically adapt to low pH in continuous culture. FEMS Microbiol Lett 2004. [DOI: 10.1111/j.1574-6968.2004.tb09550.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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46
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Matsumoto M, Ohishi H, Benno Y. H+-ATPase activity in Bifidobacterium with special reference to acid tolerance. Int J Food Microbiol 2004; 93:109-13. [PMID: 15135587 DOI: 10.1016/j.ijfoodmicro.2003.10.009] [Citation(s) in RCA: 132] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2003] [Revised: 08/09/2003] [Accepted: 10/10/2003] [Indexed: 10/26/2022]
Abstract
The acid tolerance of 17 strains of nine species of bifidobacteria was compared using brief exposures to acidic conditions (pH 2-5). In addition, because it has been hypothesized that the acid tolerance of bifidobacteria depends on H+-ATPase activity, the activity of this enzyme in various strains and species was compared. In general, the acid tolerance of bifidobacteria was found to be weak, with the exception of Bifidobacterium lactis and Bifidobacterium animalis. High numbers of all strains of B. lactis and B. animalis survived exposure to pH 3-5 for 3 h. The H+-ATPase activity of the acid-tolerant strains B. lactis LKM512 and JCM 10602T, and B. animalis JCM 1190T, JCM 1253, JCM 7117, and JCM 7124 was higher at pH 4 than at pH 5. In contrast, the H+-ATPase activity of nonacid-tolerant strains was lower at pH 4 than at pH 5.
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Affiliation(s)
- Mitsuharu Matsumoto
- Fundamental Research Laboratory, Kyodo Milk Industry Co. Ltd., 20-1 Hirai, Hinode, Tokyo 190-0182, Japan.
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Kobayashi H. Computer simulation of cytoplasmic pH regulation mediated by the F-type H+-ATPase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2003; 1607:211-6. [PMID: 14670611 DOI: 10.1016/j.bbabio.2003.10.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cytoplasmic pH regulation mediated by the H(+)-ATPase was examined with the aid of computer simulation. The data obtained with our simulation model were consistent with the experimental data and the simulation clarified the following points that may be difficult to be clarified with experimental studies. (1) The change in the enzyme amount controlled by cytoplasmic pH was essential for the pH regulation. (2) No significant change in internal pH was observed in acidic surroundings even if the proton transport activity of the H(+)-ATPase changed greater than sixfold. (3) The cytoplasmic pH homeostasis can be maintained even when the biosynthetic rate of the enzyme decreased by 50%. These results suggested that this regulatory system has an ability to maintain the pH in homeostasis even under harsh conditions that decrease cellular metabolic activities.
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Affiliation(s)
- Hiroshi Kobayashi
- Graduate School of Pharmaceutical Sciences, Chiba University, 1-33, Yayoi-cho, Inage, Chiba 263-8522, Japan.
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48
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Hicks DB, Wang Z, Wei Y, Kent R, Guffanti AA, Banciu H, Bechhofer DH, Krulwich TA. A tenth atp gene and the conserved atpI gene of a Bacillus atp operon have a role in Mg2+ uptake. Proc Natl Acad Sci U S A 2003; 100:10213-8. [PMID: 12917488 PMCID: PMC193541 DOI: 10.1073/pnas.1832982100] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2003] [Indexed: 11/18/2022] Open
Abstract
The atp operon of alkaliphilic Bacillus pseudofirmus OF4, as in most prokaryotes, contains the eight structural genes for the F-ATPase (ATP synthase), which are preceded by an atpI gene that encodes a membrane protein of unknown function. A tenth gene, atpZ, has been found in this operon, which is upstream of and overlapping with atpI. Most Bacillus species, and some other bacteria, possess atpZ homologues. AtpZ is predicted to be a membrane protein with a hairpin topology, and was detected by Western analyses. Deletion of atpZ, atpI, or atpZI from B. pseudofirmus OF4 led to a requirement for a greatly increased concentration of Mg2+ for growth at pH 7.5. Either atpZ, atpI, or atpZI complemented the similar phenotype of a triple mutant of Salmonella typhimurium (MM281), which is deficient in Mg2+ uptake. atpZ and atpI, separately and together, increased the Mg2+-sensitive 45Ca2+ uptake by vesicles of an Escherichia coli mutant that is defective in Ca2+ and Na+ efflux. We hypothesize that AtpZ and AtpI, as homooligomers, and perhaps as heterooligomers, are Mg2+ transporter, Ca2+ transporter, or channel proteins. Such proteins could provide Mg2+, which is required by ATP synthase, and also support charge compensation, when the enzyme is functioning in the hydrolytic direction; e.g., during cytoplasmic pH regulation.
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Affiliation(s)
- David B Hicks
- Department of Pharmacology and Biological Chemistry, Mount Sinai School of Medicine, New York, NY 10029, USA
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Cotter PD, Hill C. Surviving the acid test: responses of gram-positive bacteria to low pH. Microbiol Mol Biol Rev 2003; 67:429-53, table of contents. [PMID: 12966143 PMCID: PMC193868 DOI: 10.1128/mmbr.67.3.429-453.2003] [Citation(s) in RCA: 772] [Impact Index Per Article: 36.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Gram-positive bacteria possess a myriad of acid resistance systems that can help them to overcome the challenge posed by different acidic environments. In this review the most common mechanisms are described: i.e., the use of proton pumps, the protection or repair of macromolecules, cell membrane changes, production of alkali, induction of pathways by transcriptional regulators, alteration of metabolism, and the role of cell density and cell signaling. We also discuss the responses of Listeria monocytogenes, Rhodococcus, Mycobacterium, Clostridium perfringens, Staphylococcus aureus, Bacillus cereus, oral streptococci, and lactic acid bacteria to acidic environments and outline ways in which this knowledge has been or may be used to either aid or prevent bacterial survival in low-pH environments.
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Affiliation(s)
- Paul D Cotter
- Department of Microbiology and National Food Biotechnology Centre, University College Cork, Cork, Ireland
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50
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Even S, Lindley ND, Cocaign-Bousquet M. Transcriptional, translational and metabolic regulation of glycolysis in Lactococcus lactis subsp. cremoris MG 1363 grown in continuous acidic cultures. MICROBIOLOGY (READING, ENGLAND) 2003; 149:1935-1944. [PMID: 12855744 DOI: 10.1099/mic.0.26146-0] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The physiological behaviour of Lactococcus lactis subsp. cremoris MG 1363 was characterized in continuous culture under various acidic conditions (pH 4.7-6.6). Biomass yield was diminished in cultures with low pH and the energy dedicated to maintenance increased due to organic acid inhibition and cytoplasmic acidification. Under such acidic conditions, the specific rate of glucose consumption by the bacterium increased, thereby enhancing energy supply. This acceleration of glycolysis was regulated by both an increase in the concentrations of glycolytic enzymes (hierarchical regulation) and the specific modulation of enzyme activities (metabolic regulation). However, when the inhibitory effect of intracellular pH on enzyme activity was taken into account in the model of regulation, metabolite regulation was shown to be the dominant factor controlling pathway flux. The changes in glycolytic enzyme concentrations were not correlated directly to modifications in transcript concentrations. Analyses of the relative contribution of the phenomena controlling enzyme synthesis indicated that translational regulation had a major influence compared to transcriptional regulation. An increase in the translation efficiency was accompanied by an important decrease of total cellular RNA concentrations, confirming that the translation apparatus of L. lactis was optimized under acid stress conditions.
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Affiliation(s)
- Sergine Even
- Laboratoire Biotechnologie-Bioprocédés, UMR 5504 INSA/CNRS, UMR 792 INSA/INRA, Institut National des Sciences Appliquées, 135 Avenue de Rangueil, 31077 Toulouse Cedex 4, France
| | - Nic D Lindley
- Laboratoire Biotechnologie-Bioprocédés, UMR 5504 INSA/CNRS, UMR 792 INSA/INRA, Institut National des Sciences Appliquées, 135 Avenue de Rangueil, 31077 Toulouse Cedex 4, France
| | - Muriel Cocaign-Bousquet
- Laboratoire Biotechnologie-Bioprocédés, UMR 5504 INSA/CNRS, UMR 792 INSA/INRA, Institut National des Sciences Appliquées, 135 Avenue de Rangueil, 31077 Toulouse Cedex 4, France
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