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Worthan SB, McCarthy RDP, Delaleau M, Stikeleather R, Bratton BP, Boudvillain M, Behringer MG. Evolution of pH-sensitive transcription termination during adaptation to repeated long-term starvation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.01.582989. [PMID: 38464051 PMCID: PMC10925284 DOI: 10.1101/2024.03.01.582989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
Fluctuating environments that consist of regular cycles of co-occurring stress are a common challenge faced by cellular populations. For a population to thrive in constantly changing conditions, an ability to coordinate a rapid cellular response is essential. Here, we identify a mutation conferring an arginine-to-histidine (Arg to His) substitution in the transcription terminator Rho. The rho R109H mutation frequently arose in E. coli populations experimentally evolved under repeated long-term starvation conditions, during which feast and famine result in drastic environmental pH fluctuations. Metagenomic sequencing revealed that populations containing the rho mutation also possess putative loss-of-function mutations in ydcI, which encodes a recently characterized transcription factor associated with pH homeostasis. Genetic reconstructions of these mutations show that the rho allele confers a plastic alkaline-induced reduction of Rho function that, when found in tandem with a ΔydcI allele, leads to intracellular alkalinization and genetic assimilation of Rho mutant function. We further identify Arg to His substitutions at analogous sites in rho alleles from species originating from fluctuating alkaline environments. Our results suggest that Arg to His substitutions in global regulators of gene expression can serve to rapidly coordinate complex responses through pH sensing and shed light on how cellular populations across the tree of life use environmental cues to coordinate rapid responses to complex, fluctuating environments.
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Affiliation(s)
- Sarah B Worthan
- Department of Biological Sciences, Vanderbilt University, Nashville, TN
- Evolutionary Studies Initiative, Vanderbilt University, Nashville, TN
- Vanderbilt Institute for Infection, Immunology and Inflammation, Nashville, TN
| | | | - Mildred Delaleau
- Centre de Biophysique Moléculaire, CNRS UPR4301, affiliated with Université d'Orléans, rue Charles Sadron, 45071 Orléans cedex 2, France
| | - Ryan Stikeleather
- Biodesign Center for Mechanisms of Evolution, Arizona State University, Tempe, AZ
| | - Benjamin P Bratton
- Evolutionary Studies Initiative, Vanderbilt University, Nashville, TN
- Vanderbilt Institute for Infection, Immunology and Inflammation, Nashville, TN
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN
| | - Marc Boudvillain
- Centre de Biophysique Moléculaire, CNRS UPR4301, affiliated with Université d'Orléans, rue Charles Sadron, 45071 Orléans cedex 2, France
| | - Megan G Behringer
- Department of Biological Sciences, Vanderbilt University, Nashville, TN
- Evolutionary Studies Initiative, Vanderbilt University, Nashville, TN
- Vanderbilt Institute for Infection, Immunology and Inflammation, Nashville, TN
- Biodesign Center for Mechanisms of Evolution, Arizona State University, Tempe, AZ
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2
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Kubota H, Serata M, Matsumoto H, Shida K, Okumura T. Detection of Glycolytically Active Lacticaseibacillus paracasei Strain Shirota by Flow Cytometry Targeting the Efflux Activity of Fluorescent Dye: a Potential Tool for Quality Assessment of Probiotic Cells in Milk Products. Appl Environ Microbiol 2023; 89:e0215622. [PMID: 37022200 PMCID: PMC10132099 DOI: 10.1128/aem.02156-22] [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: 12/22/2022] [Accepted: 03/21/2023] [Indexed: 04/07/2023] Open
Abstract
The rapid and accurate detection of viable probiotic cells in dairy products is important for assessing product quality in manufacturing. Flow cytometry is widely used for the rapid analysis of bacterial cells. However, further investigation is needed into the optimum property to use it for assessing cell viability. Here, we proposed using the efflux activity of a fluorescent dye, carboxyfluorescein (CF), as an indicator of cell viability. CF is generated from 5(6)-carboxyfluorescein diacetate as a result of cleavage by intracellular esterase. It generally accumulates in the cell, but certain bacterial species are known to extrude it. We found here that the probiotic strain Lacticaseibacillus paracasei strain Shirota (LcS) also extruded CF in the presence of energy sources, such as glucose. To investigate the mechanism of its CF-efflux activity, we screened CF-efflux-negative mutants from a random mutagenesis LcS library and examined the whole genome for genes responsible for CF efflux. We identified a base substitution in the pfkA gene in the glycolytic pathway, and we demonstrated that intact pfkA was essential for CF efflux, indicating that CF-efflux-positive cells must have uncompromised glycolytic activity. We also confirmed that there was a good correlation between the rate of CF-efflux-positive cells and that of colony-forming cells of LcS in a fermented milk product, whereas other properties, such as esterase activity and cell membrane integrity, lost their correlation with the colony-forming activity after long storage. We propose that CF-efflux activity could be an appropriate indicator of cell viability in certain probiotic strains. IMPORTANCE To our knowledge, this is the first report to demonstrate that CF efflux requires uncompromised glycolytic activity in certain lactic acid bacteria. Compared with the cell properties currently widely used for cell viability assessment, such as intracellular esterase activity and membrane integrity, CF-efflux activity enables the accurate detection of culturable cells, especially in products stored for long periods at cold temperatures. These results indicate strongly that CF-efflux activity can be an adequate cell-viability indicator and that flow cytometric quantification could be an alternative to conventional CFU counting. Our findings should be especially informative for dairy/probiotic product manufacturing.
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Affiliation(s)
| | | | | | - Kan Shida
- Yakult Central Institute, Tokyo, Japan
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3
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Deciphering the induction of Listeria monocytogenes into sublethal injury using fluorescence microscopy and RT-qPCR. Int J Food Microbiol 2023; 385:109983. [DOI: 10.1016/j.ijfoodmicro.2022.109983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 10/16/2022] [Accepted: 10/17/2022] [Indexed: 11/22/2022]
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4
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Bouix M, Ghorbal S, Picque D, Perret B, Saulou-Berion C. A rapid method for the assessment of the vitality of microorganisms using flow cytometry. Cytometry A 2022; 101:577-587. [PMID: 35324070 DOI: 10.1002/cyto.a.24553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 02/25/2022] [Accepted: 03/15/2022] [Indexed: 11/06/2022]
Abstract
Cultivability, viability and vitality make it possible to characterize the behavior of a cellular population. Vitality was assessed using the kinetic parameters of specific metabolisms depending on whether the strains were used, for example, for the acidification of lactic acid bacteria or for CO2 production in fermenting yeasts. However, these methods are time-consuming. We developed a cytometric descriptor based on the energy-dependent extrusion of carboxyfluorescein from cells, subsequent to carboxyfluorescein diacetate staining, and compared it to the measurements of metabolic activities of various bacteria and yeasts. For all of the microorganisms tested, the cytometric descriptor ΔFI15 was well correlated with the results of the metabolic measurements and, moreover, has the advantage of being easier and faster to use than metabolic methods. It can be very useful for evaluating the vitality of the starters before inoculation in industrial processes. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Marielle Bouix
- Université Paris-Saclay, AgroParisTech, INRAe, UMR SayFood, Thiverval-Grignon, France
| | - Sarrah Ghorbal
- Université Paris-Saclay, AgroParisTech, INRAe, UMR SayFood, Thiverval-Grignon, France
| | - Daniel Picque
- Université Paris-Saclay, AgroParisTech, INRAe, UMR SayFood, Thiverval-Grignon, France
| | - Bruno Perret
- Université Paris-Saclay, AgroParisTech, INRAe, UMR SayFood, Thiverval-Grignon, France
| | - Claire Saulou-Berion
- Université Paris-Saclay, AgroParisTech, INRAe, UMR SayFood, Thiverval-Grignon, France
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5
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Du S, Hernández-Gil J, Dong H, Zheng X, Lyu G, Bañobre-López M, Gallo J, Sun LD, Yan CH, Long NJ. Design and validation of a new ratiometric intracellular pH imaging probe using lanthanide-doped upconverting nanoparticles. Dalton Trans 2017; 46:13957-13965. [DOI: 10.1039/c7dt02418e] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
A ratiometric probe based on upconversion nanoparticles modified with a pH sensitive moiety for the quantitative imaging of pH at the subcellular level in living cells.
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Affiliation(s)
- Shuoren Du
- State Key Laboratory of Rare Earth Materials Chemistry and Applications
- Peking University
- Beijing 100871
- China
| | | | - Hao Dong
- State Key Laboratory of Rare Earth Materials Chemistry and Applications
- Peking University
- Beijing 100871
- China
| | - Xiaoyu Zheng
- State Key Laboratory of Rare Earth Materials Chemistry and Applications
- Peking University
- Beijing 100871
- China
| | - Guangming Lyu
- State Key Laboratory of Rare Earth Materials Chemistry and Applications
- Peking University
- Beijing 100871
- China
| | - Manuel Bañobre-López
- Advanced (Magnetic) Theranostic Nanostructures group
- INL-International Iberian Nanotechnology Laboratory
- 4715-330 Braga
- Portugal
| | - Juan Gallo
- Advanced (Magnetic) Theranostic Nanostructures group
- INL-International Iberian Nanotechnology Laboratory
- 4715-330 Braga
- Portugal
| | - Ling-dong Sun
- State Key Laboratory of Rare Earth Materials Chemistry and Applications
- Peking University
- Beijing 100871
- China
| | - Chun-hua Yan
- State Key Laboratory of Rare Earth Materials Chemistry and Applications
- Peking University
- Beijing 100871
- China
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6
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Zou X, Pan T, Chen L, Tian Y, Zhang W. Luminescence materials for pH and oxygen sensing in microbial cells - structures, optical properties, and biological applications. Crit Rev Biotechnol 2016; 37:723-738. [PMID: 27627832 DOI: 10.1080/07388551.2016.1223011] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Luminescence including fluorescence and phosphorescence sensors have been demonstrated to be important for studying cell metabolism, and diagnosing diseases and cancer. Various design principles have been employed for the development of sensors in different formats, such as organic molecules, polymers, polymeric hydrogels, and nanoparticles. The integration of the sensing with fluorescence imaging provides valuable tools for biomedical research and applications at not only bulk-cell level but also at single-cell level. In this article, we critically reviewed recent progresses on pH, oxygen, and dual pH and oxygen sensors specifically for their application in microbial cells. In addition, we focused not only on sensor materials with different chemical structures, but also on design and applications of sensors for better understanding cellular metabolism of microbial cells. Finally, we also provided an outlook for future materials design and key challenges in reaching broad applications in microbial cells.
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Affiliation(s)
- Xianshao Zou
- a Department of Materials Science and Engineering , South University of Science and Technology of China , Shenzhen , Guangdong , P.R. China
| | - Tingting Pan
- a Department of Materials Science and Engineering , South University of Science and Technology of China , Shenzhen , Guangdong , P.R. China
| | - Lei Chen
- b Laboratory of Synthetic Microbiology, School of Chemical Engineering & Technology , Tianjin University , Tianjin , P.R. China.,c Key Laboratory of Systems Bioengineering, Ministry of Education of China , Tianjin , P.R. China.,d SynBio Platform, Collaborative Innovation Center of Chemical Science and Engineering , Tianjin , P.R. China
| | - Yanqing Tian
- a Department of Materials Science and Engineering , South University of Science and Technology of China , Shenzhen , Guangdong , P.R. China
| | - Weiwen Zhang
- b Laboratory of Synthetic Microbiology, School of Chemical Engineering & Technology , Tianjin University , Tianjin , P.R. China.,c Key Laboratory of Systems Bioengineering, Ministry of Education of China , Tianjin , P.R. China.,d SynBio Platform, Collaborative Innovation Center of Chemical Science and Engineering , Tianjin , P.R. China
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7
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Kolek J, Branska B, Drahokoupil M, Patakova P, Melzoch K. Evaluation of viability, metabolic activity and spore quantity in clostridial cultures during ABE fermentation. FEMS Microbiol Lett 2016; 363:fnw031. [PMID: 26862145 DOI: 10.1093/femsle/fnw031] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 02/03/2016] [Indexed: 01/10/2023] Open
Abstract
Flow cytometry, in combination with fluorescent staining, was used to evaluate population heterogeneity in acetone-butanol-ethanol fermentation that was carried out with type strain Clostridium beijerinckii NCIMB 8052 and non-type C. pasteurianum NRRL B-598. A combination of propidium iodide (PI) and carboxyfluorescein diacetate (CFDA), PI plus Syto-9 and bis-oxonol (BOX) alone were employed to distinguish between active and damaged cells together with simultaneous detection of spores. These strategies provided valuable information on the physiological state of clostridia. CFDA and PI staining gave the best separation of four distinct subpopulations of enzymatically active cells, doubly stained cells, damaged cells and spores. Proportional representation of cells in particular sub-regions correlated with growth characteristics, fermentation parameters such as substrate consumption and product formation in both species under different cultivation conditions.
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Affiliation(s)
- Jan Kolek
- Department of Biotechnology, University of Chemistry and Technology Prague, Technicka 5, 16628 Prague, Czech Republic
| | - Barbora Branska
- Department of Biotechnology, University of Chemistry and Technology Prague, Technicka 5, 16628 Prague, Czech Republic
| | - Marek Drahokoupil
- Department of Biotechnology, University of Chemistry and Technology Prague, Technicka 5, 16628 Prague, Czech Republic
| | - Petra Patakova
- Department of Biotechnology, University of Chemistry and Technology Prague, Technicka 5, 16628 Prague, Czech Republic
| | - Karel Melzoch
- Department of Biotechnology, University of Chemistry and Technology Prague, Technicka 5, 16628 Prague, Czech Republic
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8
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Cao G, Zhang M, Miao J, Li W, Wang J, Lu D, Xia J. Effects of X-ray and carbon ion beam irradiation on membrane permeability and integrity in Saccharomyces cerevisiae cells. JOURNAL OF RADIATION RESEARCH 2015; 56:294-304. [PMID: 25599994 PMCID: PMC4380059 DOI: 10.1093/jrr/rru114] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Revised: 11/02/2014] [Accepted: 11/05/2014] [Indexed: 05/20/2023]
Abstract
Saccharomyces cerevisiae has served as a eukaryotic model in radiation biology studies of cellular responses to ionizing radiation (IR). Research in this field has thus far mainly been focused on DNA strand breaks, DNA base damage, or inhibition of protein activity. However, the effects of IR on S. cerevisiae cell membranes have barely been studied. Here, we investigated the changes in the permeability and integrity of S. cerevisiae cell membranes induced by high-linear energy transfer carbon ion (CI) beam or low-linear energy transfer X-ray. After CI exposure, protein elution and nucleotide diffusion were more pronounced than after X-ray treatment at the same doses, although these features were most prevalent following irradiation doses of 25-175 Gy. Flow cytometry of forward scatter light versus side scatter light and double-staining with fluorescein diacetate and propidium iodide showed that CI and X-ray irradiation significantly affected S. cerevisiae cell membrane integrity and cellular enzyme activity compared with untreated control cells. The extent of lesions in CI-irradiated cells, which exhibited markedly altered morphology and size, was greater than that in X-ray-irradiated cells. The relationships between permeabilized cells, esterase activity, and non-viable cell numbers furthermore indicated that irradiation-induced increases in cell permeabilization and decreases in esterase activity are dependent on the type of radiation and that these parameters correspond well with cell viability. These results also indicate that the patterns of cell inactivity due to X-ray or CI irradiation may be similar in terms of cell membrane damage.
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Affiliation(s)
- Guozhen Cao
- Institute of Modern Physics, Chinese Academy of Sciences, Lan zhou 730000, China School of Pharmacy, Lanzhou University, Lan zhou 730000, China Key Laboratory of Microbial Resources Exploition and Application, Lan zhou 730000, China
| | - Miaomiao Zhang
- Institute of Modern Physics, Chinese Academy of Sciences, Lan zhou 730000, China Key Laboratory of Microbial Resources Exploition and Application, Lan zhou 730000, China
| | - Jianshun Miao
- Institute of Modern Physics, Chinese Academy of Sciences, Lan zhou 730000, China Key Laboratory of Microbial Resources Exploition and Application, Lan zhou 730000, China
| | - Wenjian Li
- Institute of Modern Physics, Chinese Academy of Sciences, Lan zhou 730000, China Key Laboratory of Microbial Resources Exploition and Application, Lan zhou 730000, China
| | - Jufang Wang
- Institute of Modern Physics, Chinese Academy of Sciences, Lan zhou 730000, China Key Laboratory of Microbial Resources Exploition and Application, Lan zhou 730000, China
| | - Dong Lu
- Institute of Modern Physics, Chinese Academy of Sciences, Lan zhou 730000, China Key Laboratory of Microbial Resources Exploition and Application, Lan zhou 730000, China
| | - Jiefang Xia
- Institute of Modern Physics, Chinese Academy of Sciences, Lan zhou 730000, China School of Pharmacy, Lanzhou University, Lan zhou 730000, China Key Laboratory of Microbial Resources Exploition and Application, Lan zhou 730000, China
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9
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Cortes PR, Piñas GE, Cian MB, Yandar N, Echenique J. Stress-triggered signaling affecting survival or suicide of Streptococcus pneumoniae. Int J Med Microbiol 2014; 305:157-69. [PMID: 25543170 DOI: 10.1016/j.ijmm.2014.12.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Revised: 12/01/2014] [Accepted: 12/01/2014] [Indexed: 01/27/2023] Open
Abstract
Streptococcus pneumoniae is a major human pathogen that can survive to stress conditions, such as the acidic environment of inflammatory foci, and tolerates lethal pH through a mechanism known as the acid tolerance response. We previously described that S. pneumoniae activates acidic-stress induced lysis in response to acidified environments, favoring the release of cell wall compounds, DNA and virulence factors. Here, we demonstrate that F(0)F(1)-ATPase is involved in the response to acidic stress. Chemical inhibitors (DCCD, optochin) of this proton pump repressed the ATR induction, but caused an increased ASIL. Confirming these findings, mutants of the subunit c of this enzyme showed the same phenotypes as inhibitors. Importantly, we demonstrated that F(0)F(1)-ATPase and ATR are necessary for the intracellular survival of the pneumococcus in macrophages. Alternatively, a screening of two-component system (TCS) mutants showed that ATR and survival in pneumocytes were controlled in contrasting ways by ComDE and CiaRH, which had been involved in the ASIL mechanism. Briefly, CiaRH was essential for ATR (ComE represses activation) whereas ComE was necessary for ASIL (CiaRH protects against induction). They did not regulate F0F1-ATPase expression, but control LytA expression on the pneumococcal surface. These results suggest that both TCSs and F(0)F(1)-ATPase control a stress response and decide between a survival or a suicide mechanism by independent pathways, either in vitro or in pneumocyte cultures. This biological model contributes to the current knowledge about bacterial response under stress conditions in host tissues, where pathogens need to survive in order to establish infections.
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Affiliation(s)
- Paulo R Cortes
- Departamento de Bioquímica Clínica-CIBICI (CONICET), Facultad de Ciencias Químicas, Universidad Nacional de Cordoba, Medina Allende esq. Haya de la Torre, Ciudad Universitaria, CP, X5000HUA Cordoba, Argentina
| | - Germán E Piñas
- Departamento de Bioquímica Clínica-CIBICI (CONICET), Facultad de Ciencias Químicas, Universidad Nacional de Cordoba, Medina Allende esq. Haya de la Torre, Ciudad Universitaria, CP, X5000HUA Cordoba, Argentina
| | - Melina B Cian
- Departamento de Bioquímica Clínica-CIBICI (CONICET), Facultad de Ciencias Químicas, Universidad Nacional de Cordoba, Medina Allende esq. Haya de la Torre, Ciudad Universitaria, CP, X5000HUA Cordoba, Argentina
| | - Nubia Yandar
- Departamento de Bioquímica Clínica-CIBICI (CONICET), Facultad de Ciencias Químicas, Universidad Nacional de Cordoba, Medina Allende esq. Haya de la Torre, Ciudad Universitaria, CP, X5000HUA Cordoba, Argentina
| | - Jose Echenique
- Departamento de Bioquímica Clínica-CIBICI (CONICET), Facultad de Ciencias Químicas, Universidad Nacional de Cordoba, Medina Allende esq. Haya de la Torre, Ciudad Universitaria, CP, X5000HUA Cordoba, Argentina.
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10
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Schaedler TA, Tong Z, van Veen HW. The multidrug transporter LmrP protein mediates selective calcium efflux. J Biol Chem 2012; 287:27682-90. [PMID: 22730320 DOI: 10.1074/jbc.m112.372334] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
LmrP is a major facilitator superfamily multidrug transporter from Lactococcus lactis that mediates the efflux of cationic amphiphilic substrates from the cell in a proton-motive force-dependent fashion. Interestingly, motif searches and docking studies suggested the presence of a putative Ca(2+)-binding site close to the interface between the two halves of inward facing LmrP. Binding experiments with radioactive (45)Ca(2+) demonstrated the presence of a high affinity Ca(2+)-binding site in purified LmrP, with an apparent K(d) of 7.2 μm, which is selective for Ca(2+) and Ba(2+) but not for Mn(2+), Mg(2+), or Co(2+). Consistent with our structure model and analogous to crystal structures of EF hand Ca(2+)-binding proteins, two carboxylates (Asp-235 and Glu-327) were found to be critical for (45)Ca(2+) binding. Using (45)Ca(2+) and a fluorescent Ca(2+)-selective probe, calcium transport measurements in intact cells, inside-out membrane vesicles, and proteoliposomes containing functionally reconstituted purified protein provided strong evidence for active efflux of Ca(2+) by LmrP with an apparent K(t) of 8.6 μm via electrogenic exchange with three or more protons. These observations demonstrate for the first time that LmrP mediates selective calcium/proton antiport and raise interesting questions about the functional and physiological links between this reaction and that of multidrug transport.
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11
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Tracking bacterial infection of macrophages using a novel red-emission pH sensor. Anal Bioanal Chem 2010; 398:1375-84. [PMID: 20721541 DOI: 10.1007/s00216-010-4060-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2010] [Revised: 07/20/2010] [Accepted: 07/21/2010] [Indexed: 10/19/2022]
Abstract
The relationship between bacteria and host phagocytic cells is key to the induction of immunity. To visualize and monitor bacterial infection, we developed a novel bacterial membrane permeable pH sensor for the noninvasive monitoring of bacterial entry into murine macrophages. The pH sensor was constructed using 2-dicyanomethylene-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran (TCF) as an electron-withdrawing group and aniline as an electron-donating group. A piperazine moiety was used as the pH-sensitive group. Because of the strong electron-donating and -withdrawing units conjugated in the sensing moiety M, the fluorophore emitted in the red spectral window, away from the autofluorescence regions of the bacteria. Following the engulfment of sensor-labeled bacteria by macrophages and their subsequent merger with host lysosomes, the resulting low-pH environment enhances the fluorescence intensity of the pH sensors inside the bacteria. Time-lapse analysis of the fluorescent intensity suggested significant heterogeneity of bacterial uptake among macrophages. In addition, qRT-PCR analysis of the bacterial 16 S rRNA gene expression within single macrophage cells suggested that the 16 S rRNA of the bacteria was still intact 120 min after they had been engulfed by macrophages. A toxicity assay showed that the pH sensor has no cytotoxicity towards either E. coli or murine macrophages. The sensor shows good repeatability, a long lifetime, and a fast response to pH changes, and can be used for a variety of bacteria.
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12
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Müller S, Nebe-von-Caron G. Functional single-cell analyses: flow cytometry and cell sorting of microbial populations and communities. FEMS Microbiol Rev 2010; 34:554-87. [DOI: 10.1111/j.1574-6976.2010.00214.x] [Citation(s) in RCA: 266] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
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13
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Breeuwer P, Drocourt J, Rombouts FM, Abee T. A Novel Method for Continuous Determination of the Intracellular pH in Bacteria with the Internally Conjugated Fluorescent Probe 5 (and 6-)-Carboxyfluorescein Succinimidyl Ester. Appl Environ Microbiol 2010; 62:178-83. [PMID: 16535209 PMCID: PMC1388751 DOI: 10.1128/aem.62.1.178-183.1996] [Citation(s) in RCA: 193] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A novel method based on the intracellular conjugation of the fluorescent probe 5 (and 6-)-carboxyfluorescein succinimidyl ester (cFSE) was developed to determine the intracellular pH of bacteria. cFSE can be taken up by bacteria in the form of its diacetate ester, 5 (and 6-)-carboxyfluorescein diacetate succinimidyl ester, which is subsequently hydrolyzed by esterases to cFSE in the cytoplasm. When Lactococcus lactis cells were permeabilized with ethanol, a significant proportion of cFSE was retained in the cells, which indicated that cFSE was bound intracellularly. Unbound probe could be conveniently extruded by a short incubation of the cells in the presence of a fermentable sugar, most likely by exploiting an active transport system. Such a transport system for cFSE was identified in L. lactis, Listeria innocua, and Bacillus subtilis. The intracellular pH in bacteria can be determined from the ratio of the fluorescence signal at the pH-sensitive wavelength (490 nm) and the fluorescence signal at the pH-insensitive wavelength (440 nm). This cFSE ratio method significantly reduced problems due to the efflux of fluorescent probe from the cells during the measurement. Moreover, the method described was successfully used to determine the intracellular pH in bacteria under stress conditions, such as elevated temperatures and the presence of detergents.
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14
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Da Silveira MG, Abee T. Activity of ethanol-stressed Oenococcus oeni cells: a flow cytometric approach. J Appl Microbiol 2009; 106:1690-6. [PMID: 19226398 DOI: 10.1111/j.1365-2672.2008.04136.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
AIMS To study the effect of ethanol on Oenococcus oeni activity at the single cell level. METHODS AND RESULTS The active extrusion of the fluorescent probe carboxy fluorescein (cF) was used to assess the metabolic activity of ethanol-stressed O. oeni cells. Subsequent flow cytometric analysis revealed that O. oeni cells extrude the accumulated cF upon energizing with l-malic acid. However, O. oeni cells exposed to 12% (v/v) ethanol for 1 h showed a decreased capacity for active extrusion of cF. Moreover, two subpopulations could be distinguished, one of which being able to extrude cF and the other one remaining cF fluorescent. Growing cells in the presence of 8% (v/v) ethanol resulted in robust cells that maintained the capacity to actively extrude cF after being exposed to 12% (v/v) ethanol, which in turn correlated with the high levels of ATP observed in these ethanol stressed, malolactic fermentation (MLF) performing cells. CONCLUSION From our results, it becomes evident that active extrusion of cF can be used to assess malolactic activity in O. oeni. SIGNIFICANCE AND IMPACT OF THE STUDY The present study provides information for the development of a rapid method to assess the malolactic activity of individual O. oeni cells performing MLF during wine production.
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Affiliation(s)
- M G Da Silveira
- Departamento de Ciências Agrárias, Universidade dos Açores, Angra do Heroísmo, Portugal.
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15
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Konings WN. Microbial transport: Adaptations to natural environments. Antonie van Leeuwenhoek 2006; 90:325-42. [PMID: 17043914 DOI: 10.1007/s10482-006-9089-3] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2006] [Accepted: 05/11/2006] [Indexed: 11/25/2022]
Abstract
The cytoplasmic membrane of bacteria is the matrix for metabolic energy transducing processes such as proton motive force generation and solute transport. Passive permeation of protons across the cytoplasmic membrane is a crucial determinant in the proton motive generating capacity of the organisms. Adaptations of the membrane composition are needed to restrict the proton permeation rates especially at higher temperatures. Thermophilic bacteria cannot sufficiently restrict this proton permeation at their growth temperature and have to rely on the much lower permeation of Na + to generate a sodium motive force for driving metabolic energy-dependent membrane processes. Specific transport systems mediate passage across the membrane at physiological rates of all compounds needed for growth and metabolism and of all end products of metabolism. Some of transport systems, the secondary transporters, transduce one form of electrochemical energy into another form. These transporters can play crucial roles in the generation of metabolic energy. This is especially so in anaerobes such as Lactic Acid Bacteria which live under energy-limited conditions. Several transport systems are specifically aimed at the generation of metabolic energy during periods of energy-limitation. In their natural environment bacteria are also often exposed to cytotoxic compounds, including antibiotics. Many bacteria can respond to this live-threatening condition by overexpressing powerful drug-extruding multidrug resistance systems.
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Affiliation(s)
- Wil N Konings
- Department of Microbiology, Groningen Bio-molecular Sciences and Biotechnology Center, University of Groningen, Kerklaan 30, 9751 NN, Haren, The Netherlands.
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16
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Amanullah A, Hewitt CJ, Nienow AW, Lee C, Chartrain M, Buckland BC, Drew SW, Woodley JM. Measurement of strain-dependent toxicity in the indene bioconversion using multiparameter flow cytometry. Biotechnol Bioeng 2003; 81:405-20. [PMID: 12491526 DOI: 10.1002/bit.10479] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The bionconversion of indene to cis-(1S,2R)-indandiol, a potential key intermediate in the synthesis of Merck's HIV protease inhibitor, CRIXIVAN trade mark, can be achieved using Rhodococcus, Pseudomonas putida, and Escherichia coli strains. This study reports on the application of multiparameter flow cytometry for the measurement of cytoplasmic membrane integrity and membrane depolarization as indicators of toxic effects of the substrate, product, and by-products using each of these strains. Measurements of oxygen uptake rate (OUR) and optical density (OD) as indicators of metabolic activity and biomass growth, respectively, were also made. Measurements of the cytoplasmic membrane potential, cell viability, and respiratory activity provided a sensitive set of parameters to assess toxicity in the indene bioconversion and provided the basis for process improvements and strain selection. The toxic concentrations of the substrate, product, and by-products for each strain have been determined. The results show that it is possible to accumulate cis-(1S,2R)-indandiol and cis-1-amino-2-indanol up to 20 g/L without significant negative effects on cell physiology using any of the strains tested. The Gram-negative P. putida (421-5 and GM 730) and E. coli strains were more resistant to indene and the isolated chemicals of the biotransformation than the Gram-positive Rhodoccoccus I24 strain, possibly due to the presence of the outer membrane and efflux pump mechanisms. P. putida GM 730 and the E. coli TDO 123 strains responded similarly to toxic effects, and the E. coli TDO 123 strain was more resistant than the P. putida 421-5 strain. In addition to the recommendations for strain selection, the identified targets for bioprocess improvement include a combination of genetic as well as process engineering approaches.
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Affiliation(s)
- A Amanullah
- Advanced Centre for Biochemical Engineering, Department of Biochemical Engineering, University College London, Torrington Place, London W1CE 7JE, United Kingdom.
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17
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18
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Poelarends GJ, Mazurkiewicz P, Konings WN. Multidrug transporters and antibiotic resistance in Lactococcus lactis. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1555:1-7. [PMID: 12206883 DOI: 10.1016/s0005-2728(02)00246-3] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The Gram-positive bacterium Lactococcus lactis produces two distinct multidrug transporters, designated LmrA and LmrP, that both confer resistance to a wide variety of cationic lipophilic cytotoxic compounds as well as to many clinically relevant antibiotics. While LmrP is a proton/drug antiporter that belongs to the major facilitator superfamily of secondary transporters, LmrA is an ATP-dependent primary transporter that belongs to the ATP-binding cassette superfamily of transport proteins. Both LmrA and LmrP function as "hydrophobic vacuum cleaners" by excreting lipophilic cationic compounds from the inner leaflet of the membrane directly into the external water phase. LmrA is both functionally and structurally homologous to the human multidrug transporter P-glycoprotein. LmrA is a half ABC transporter that is functional as a homodimer, consistent with the general four-domain organization of ABC transporters, and is proposed to mediate drug transport by an alternating two-site transport mechanism.
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Affiliation(s)
- Gerrit J Poelarends
- Department of Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Kerklaan 30, NL-9751 NN Haren, The Netherlands
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19
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Putman M, van Veen HW, Degener JE, Konings WN. The lactococcal secondary multidrug transporter LmrP confers resistance to lincosamides, macrolides, streptogramins and tetracyclines. MICROBIOLOGY (READING, ENGLAND) 2001; 147:2873-2880. [PMID: 11577166 DOI: 10.1099/00221287-147-10-2873] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The active efflux of toxic compounds by (multi)drug transporters is one of the mechanisms that bacteria have developed to resist cytotoxic drugs. The authors describe the role of the lactococcal secondary multidrug transporter LmrP in the resistance to a broad range of clinically important antibiotics. Cells expressing LmrP display an increased resistance to the lincosamide, streptogramin, tetracycline and 14- and 15-membered macrolide antibiotics. The streptogramin antibiotic quinupristin, present in the fourth-generation antibiotic RP 59500, can inhibit LmrP-mediated Hoechst 33342 transport, but is not transported by LmrP, indicating that quinupristin acts as a modulator of LmrP activity. LmrP-expressing Lactococcus lactis cells in which a proton-motive force is generated accumulate significantly less tetracycline than control cells without LmrP expression. In contrast, LmrP-expressing and control cells accumulate equal amounts of tetracycline in the absence of metabolic energy. These findings demonstrate that the increased antibiotic resistance in LmrP-expressing cells is a result of the active extrusion of antibiotics from the cell.
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Affiliation(s)
- Monique Putman
- Department of Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Kerklaan 30, 9751 NN Haren, The Netherlands1
| | - Hendrik W van Veen
- Department of Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Kerklaan 30, 9751 NN Haren, The Netherlands1
| | - John E Degener
- Department of Medical Microbiology, University of Groningen, Hanzeplein 1, 9713 GZ Groningen, The Netherlands2
| | - Wil N Konings
- Department of Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Kerklaan 30, 9751 NN Haren, The Netherlands1
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20
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Bunthof CJ, Bloemen K, Breeuwer P, Rombouts FM, Abee T. Flow cytometric assessment of viability of lactic acid bacteria. Appl Environ Microbiol 2001; 67:2326-35. [PMID: 11319119 PMCID: PMC92874 DOI: 10.1128/aem.67.5.2326-2335.2001] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The viability of lactic acid bacteria is crucial for their applications as dairy starters and as probiotics. We investigated the usefulness of flow cytometry (FCM) for viability assessment of lactic acid bacteria. The esterase substrate carboxyfluorescein diacetate (cFDA) and the dye exclusion DNA binding probes propidium iodide (PI) and TOTO-1 were tested for live/dead discrimination using a Lactococcus, a Streptococcus, three Lactobacillus, two Leuconostoc, an Enterococcus, and a Pediococcus species. Plate count experiments were performed to validate the results of the FCM assays. The results showed that cFDA was an accurate stain for live cells; in exponential-phase cultures almost all cells were labeled, while 70 degrees C heat-killed cultures were left unstained. PI did not give clear live/dead discrimination for some of the species. TOTO-1, on the other hand, gave clear discrimination between live and dead cells. The combination of cFDA and TOTO-1 gave the best results. Well-separated subpopulations of live and dead cells could be detected with FCM. Cell sorting of the subpopulations and subsequent plating on agar medium provided direct evidence that cFDA labels the culturable subpopulation and that TOTO-1 labels the nonculturable subpopulation. Applied to cultures exposed to deconjugated bile salts or to acid, cFDA and TOTO-1 proved to be accurate indicators of culturability. Our experiments with lactic acid bacteria demonstrated that the combination of cFDA and TOTO-1 makes an excellent live/dead assay with versatile applications.
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Affiliation(s)
- C J Bunthof
- Laboratory of Food Microbiology, Department of Food Technology and Nutritional Sciences, Wageningen University and Research Centre, 6700 EV Wageningen, The Netherlands
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21
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Joux F, Lebaron P. Use of fluorescent probes to assess physiological functions of bacteria at single-cell level. Microbes Infect 2000; 2:1523-35. [PMID: 11099939 DOI: 10.1016/s1286-4579(00)01307-1] [Citation(s) in RCA: 241] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
A wide diversity of fluorescent probes is currently available to assess the physiological state of microorganisms. The recent development of techniques such as solid-phase cytometry, the increasing sensitivity of fluorescence tools and multiparametric approaches combining taxonomic and physiological probes have improved the effectiveness of direct methods in environmental and industrial microbiology.
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Affiliation(s)
- F Joux
- Observatoire océanologique, université Pierre et Marie Curie, UMR-7621 CNRS, Institut national des sciences de l'Univers, BP 44, F-66651 cedex, Banyuls-sur-Mer, France
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22
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Vives-Rego J, Lebaron P, Nebe-von Caron G. Current and future applications of flow cytometry in aquatic microbiology. FEMS Microbiol Rev 2000; 24:429-48. [PMID: 10978545 DOI: 10.1111/j.1574-6976.2000.tb00549.x] [Citation(s) in RCA: 170] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Flow cytometry has become a valuable tool in aquatic and environmental microbiology that combines direct and rapid assays to determine numbers, cell size distribution and additional biochemical and physiological characteristics of individual cells, revealing the heterogeneity present in a population or community. Flow cytometry exhibits three unique technical properties of high potential to study the microbiology of aquatic systems: (i) its tremendous velocity to obtain and process data; (ii) the sorting capacity of some cytometers, which allows the transfer of specific populations or even single cells to a determined location, thus allowing further physical, chemical, biological or molecular analysis; and (iii) high-speed multiparametric data acquisition and multivariate data analysis. Flow cytometry is now commonly used in aquatic microbiology, although the application of cell sorting to microbial ecology and quantification of heterotrophic nanoflagellates and viruses is still under development. The recent development of laser scanning cytometry also provides a new way to further analyse sorted cells or cells recovered on filter membranes or slides. The main infrastructure limitations of flow cytometry are: cost, need for skilled and well-trained operators, and adequate refrigeration systems for high-powered lasers and cell sorters. The selection and obtaining of the optimal fluorochromes, control microorganisms and validations for a specific application may sometimes be difficult to accomplish.
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Affiliation(s)
- J Vives-Rego
- Departament de Microbiologia, Universitat de Barcelona, Barcelona, Spain.
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23
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Yokota A, Veenstra M, Kurdi P, van Veen HW, Konings WN. Cholate resistance in Lactococcus lactis is mediated by an ATP-dependent multispecific organic anion transporter. J Bacteriol 2000; 182:5196-201. [PMID: 10960105 PMCID: PMC94669 DOI: 10.1128/jb.182.18.5196-5201.2000] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The cholate-resistant Lactococcus lactis strain C41-2, derived from wild-type L. lactis MG1363 through selection for growth on cholate-containing medium, displayed a reduced accumulation of cholate due to an enhanced active efflux. However, L. lactis C41-2 was not cross resistant to deoxycholate or cationic drugs, such as ethidium and rhodamine 6G, which are typical substrates of the multidrug transporters LmrP and LmrA in L. lactis MG1363. The cholate efflux activity in L. lactis C41-2 was not affected by the presence of valinomycin plus nigericin, which dissipated the proton motive force. In contrast, cholate efflux in L. lactis C41-2 was inhibited by ortho-vanadate, an inhibitor of P-type ATPases and ATP-binding cassette transporters. Besides ATP-dependent drug extrusion by LmrA, two other ATP-dependent efflux activities have previously been detected in L. lactis, one for the artificial pH probe 2',7'-bis-(2-carboxyethyl)-5(and 6)-carboxyfluorescein (BCECF) and the other for the artificial pH probe N-(fluorescein thio-ureanyl)-glutamate (FTUG). Surprisingly, the efflux rate of BCECF, but not that of FTUG, was significantly enhanced in L. lactis C41-2. Further experiments with L. lactis C41-2 cells and inside out membrane vesicles revealed that cholate and BCECF inhibit the transport of each other. These data demonstrate the role of an ATP-dependent multispecific organic anion transporter in cholate resistance in L. lactis.
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Affiliation(s)
- A Yokota
- Laboratory of Microbial Resources and Ecology, Research Group of Molecular Bioscience, Division of Applied Bioscience, Graduate School of Agriculture, Hokkaido University, Sapporo, Japan
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24
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Parthuisot N, Catala P, Lemarchand K, Baudart J, Lebaron P. Evaluation of ChemChrome V6 for bacterial viability assessment in waters. J Appl Microbiol 2000; 89:370-80. [PMID: 10971771 DOI: 10.1046/j.1365-2672.2000.01126.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The efficiency of ChemChrome B (CB) and ChemChrome V6 (CV6) dyes to stain viable bacterial cells in water was compared. Both dyes are fluorogenic esters converted to free fluorescein by esterase activity. The dyes were applied to a wide variety of bacterial species, including those poorly stained by CB, and to natural waters. Some species tested gave unacceptable low fluorescence intensities by being inefficiently or non-labelled with the CB. In contrast, CV6-stained bacteria were easily detected by both flow cytometry and solid-phase cytometry. As a consequence, higher viable cell counts were found with CV6 compared with CB in natural waters. Viable counts determined by CV6 staining were always higher than cfu counts. In contrast, respiring cell counts (CTC) were always lower than CV6 counts and, in the case of tap and mineral waters, they were lower than cfu counts.
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Affiliation(s)
- N Parthuisot
- Observatoire Océanologique, Centre National de la Recherche Scientifique, Institut National des Sciences de l'Univers et Université Pierre et Marie Curie, Banyuls-sur-Mer, France
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25
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Bunthof CJ, van den Braak S, Breeuwer P, Rombouts FM, Abee T. Fluorescence assessment of Lactococcus lactis viability. Int J Food Microbiol 2000; 55:291-4. [PMID: 10791760 DOI: 10.1016/s0168-1605(00)00170-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The reproduction and activity of lactic acid bacteria (LAB) are essential in their applications in the dairy industry and other fermentations. Traditionally used methods like plate counting and acidification tests require long incubation times and provide limited information. Fluorescence techniques provide possibilities for rapid assessment of cell physiology. We used traditional and fluorescence assays to assess the physiological condition of L. lactis subsp. lactis ML3 cultures that were exposed to various stress conditions. After exposure to some of the stress conditions, carboxyfluorescein (cF) labelling did not agree with plate counts. Therefore, a two-step method was developed in which cF labelling was followed by a lactose-energized efflux assay. The combined assay proved to be a good and rapid indicator for reproduction and acidification capacity of stressed L. lactis. This novel assay has potential for physiological research and dairy applications related to LAB.
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Affiliation(s)
- C J Bunthof
- Department of Food Technology and Nutrition Sciences, Wageningen University and Research Centre, The Netherlands
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26
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Breeuwer P, Abee T. Assessment of viability of microorganisms employing fluorescence techniques. Int J Food Microbiol 2000; 55:193-200. [PMID: 10791743 DOI: 10.1016/s0168-1605(00)00163-x] [Citation(s) in RCA: 189] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Viability assessment of microorganisms is relevant for a wide variety of applications in industry, including evaluation of inactivation treatments and quality assessment of starter cultures for beer, wine, and yoghurt production. Usually, the ability of microbial cells to reproduce is considered as the benchmark method for determination of cell viability, and this is most commonly determined by the plate count method. The time needed to form visible colonies, however, is relatively long. Therefore, there is an increasing interest in rapid methods which exploit criteria other than reproduction. In this review the applications of fluorescent probes for, e.g., determination of membrane integrity, enzyme activities, respiration, membrane potential and intracellular pH, are discussed in detail.
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Affiliation(s)
- P Breeuwer
- Department of Food Technology and Nutritional Sciences, Wageningen University and Research Centre, The Netherlands.
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27
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Müller S, Ullrich S, Lösche A, Loffhagen N, Babel W. Flow cytometric techniques to characterise physiological states of Acinetobacter calcoaceticus. J Microbiol Methods 2000; 40:67-77. [PMID: 10739345 DOI: 10.1016/s0167-7012(99)00130-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Monitoring biotechnological processes involves acquiring information about key metabolic events and, ideally, single cell states should be determined to obtain comprehensive data on the physiological status of the surveyed population. In this paper, growth stages of the strain Acinetobacter calcoaceticus 69-V were characterised at the single cell level using flow cytometry. Four methods for analysing bacterial cellular characteristics by fluorescence were compared with respect to their sensitivity to changes in the physiological states induced by changing micro-environmental conditions. DNA analysis was confirmed to be highly informative with regard to the multiplication activity of the population. Measuring the membrane potential related fluorescence intensity (MPRFI) and the rRNA content were found to be useful for describing high-active cell states. A method for the measurement of the fluidity related fluorescence intensity (FRFI) was developed, since it allowed changes in the fluidity of the bacterial membrane to be detected, and thereby provided a valuable means of tracking adaptation of the population to micro-environmental deviations from optimal growth conditions.
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Affiliation(s)
- S Müller
- Sächsisches Institut für Angewandte Biotechnologie (SIAB) an der Universität Leipzig, Germany
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28
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Bond DR, Russell JB. Protonmotive force regulates the membrane conductance of Streptococcus bovis in a non-ohmic fashion. MICROBIOLOGY (READING, ENGLAND) 2000; 146 ( Pt 3):687-694. [PMID: 10746772 DOI: 10.1099/00221287-146-3-687] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Because the DCCD (dicyclohexylcarbodiimide)-sensitive, F-ATPase-mediated, futile ATP hydrolysis of non-growing Streptococcus bovis JB1 cells was not affected by sodium or potassium, ATP hydrolysis appeared to be dependent only upon the rate of proton flux across the cell membrane. However, available estimates of bacterial proton conductance were too low to account for the rate of ATP turnover observed in S. bovis. When de-energized cells were subjected to large pH gradients (2.75 units, or -170 mV), internal pH declined at a rate of 0.15 pH units s(-1). Based on an estimated cellular buffering capacity of 200 nmol H+ (mg protein)(-1) per pH unit, H+ flux across the cell membrane (at -170 mV) was 108 mmol (g protein)(-1) h(-1). When potassium-loaded cells were treated with valinomycin in low-potassium buffers, initial K+ efflux generated membrane potentials in close agreement with values predicted by the Nernst equation. These artificial membrane potentials drove H+ uptake, and H+ influx was counterbalanced by a further loss of cellular K+. Flame photometry indicated that the rate of K+ loss was 215 (+/-26) mmol K+ (g protein)(-1) h(-1) at -170 mV, but the potassium-sensitive fluorescent compound CD222 indicated that this rate was only 110 (+/-44) mmol K+ (g protein)(-1) h(-1). As pH gradients or membrane potentials were reduced, the rate of H+ flux declined in a non-ohmic fashion, and all rates were <25 mmol (g protein)(-1) h(-1) at a driving force of -80 mV. Previous estimates of bacterial proton flux were based on low and unphysiological protonmotive forces, and the assumption that H+ influx rate would be ohmic. Rates of H+ influx into S. bovis cells [as high as 9x10(-11) mol H+ (cm membrane)(-2) s(-1)] were similar to rates reported for respiring mitochondria, but were at least 20-fold greater than any rate previously reported in lactic acid bacteria.
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Affiliation(s)
- Daniel R Bond
- Section of Microbiology, Cornell University1, and Agricultural Research Service, USDA2, Ithaca, NY 14853, USA
| | - James B Russell
- Section of Microbiology, Cornell University1, and Agricultural Research Service, USDA2, Ithaca, NY 14853, USA
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29
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van Veen HW, Konings WN. Structure and function of multidrug transporters. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1999; 456:145-58. [PMID: 10549367 DOI: 10.1007/978-1-4615-4897-3_8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- H W van Veen
- Department of Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Haren, The Netherlands.
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30
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Moll GN, van den Akker E, Hauge HH, Nissen-Meyer J, Nes IF, Konings WN, Driessen AJ. Complementary and overlapping selectivity of the two-peptide bacteriocins plantaricin EF and JK. J Bacteriol 1999; 181:4848-52. [PMID: 10438754 PMCID: PMC93971 DOI: 10.1128/jb.181.16.4848-4852.1999] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Plantaricin EF and JK are both two-peptide bacteriocins produced by Lactobacillus plantarum C11. The mechanism of plantaricin EF and JK action was studied on L. plantarum 965 cells. Both plantaricins form pores in the membranes of target cells and dissipate the transmembrane electrical potential (Deltapsi) and pH gradient (DeltapH). The plantaricin EF pores efficiently conduct small monovalent cations, but conductivity for anions is low or absent. Plantaricin JK pores show high conductivity for specific anions but low conductivity for cations. These data indicate that L. plantarum C11 produces bacteriocins with complementary ion selectivity, thereby ensuring efficient killing of target bacteria.
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Affiliation(s)
- G N Moll
- Department of Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9751NN Haren, The Netherlands
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31
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Bunthof CJ, van den Braak S, Breeuwer P, Rombouts FM, Abee T. Rapid fluorescence assessment of the viability of stressed Lactococcus lactis. Appl Environ Microbiol 1999; 65:3681-9. [PMID: 10427066 PMCID: PMC91551 DOI: 10.1128/aem.65.8.3681-3689.1999] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The aim of this study was to establish the use of the fluorescent probes carboxyfluorescein (cF) and propidium iodide (PI) for rapid assessment of viability, using Lactococcus lactis subsp. lactis ML3 exposed to different stress treatments. The cF labeling indicated the reproductive capacity of mixtures of nontreated cells and cells killed at 70 degrees C very well. However, after treatment up to 60 degrees C the fraction of cF-labeled cells remained high, whereas the survival decreased for cells treated at above 50 degrees C and was completely lost for those treated at 60 degrees C. In an extended series of experiments, cell suspensions were exposed to heating, freezing, low pH, or bile salts, after which the colony counts, acidification capacity, glycolytic activity, PI exclusion, cF labeling, and cF efflux were measured and compared. The acidification capacity corresponded with the number of CFU. The glycolytic activity, which is an indicator of vitality, was more sensitive to the stress conditions than the reproduction, acidification, and fluorescence parameters. The cF labeling depended on membrane integrity, as was confirmed by PI exclusion. The fraction of cF-labeled cells was not a general indicator of reproduction or acidification, nor was PI exclusion or cF labeling capacity (the internal cF concentration). When the cells were labeled by cF, a subsequent lactose-energized efflux assay was needed for decisive viability assessment. This novel assay proved to be a good and rapid indicator of the reproduction and acidification capacities of stressed L. lactis and has potential for physiological research and dairy applications related to lactic acid bacteria.
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Affiliation(s)
- C J Bunthof
- Department of Food Technology and Nutritional Sciences, Wageningen University and Research Centre, Wageningen, The Netherlands
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32
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van Veen HW, Konings WN. The ABC family of multidrug transporters in microorganisms. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1365:31-6. [PMID: 9693718 DOI: 10.1016/s0005-2728(98)00039-5] [Citation(s) in RCA: 109] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Multidrug transporters are membrane proteins that are able to expel a broad range of toxic molecules from the cell. In humans, the overexpression of the multidrug resistance P-glycoprotein (Pgp) and the multidrug resistance-associated protein MRP1 (MRP) is a principal cause of resistance of cancers to chemotherapy. These multidrug transporters belong to the ATP-binding cassette (ABC) family of transport proteins that utilize the energy of ATP hydrolysis for activity. In microorganisms, multidrug transporters play an important role in conferring antibiotic resistance on pathogens. In the last decade, homologs of human Pgp and MRP have been found in microorganisms such as Plasmodium falciparum, Candida albicans, Saccharomyces cerevisiae and, more recently, in Lactococcus lactis. In this review, we will summarize the current state of knowledge on three major aspects of microbial ABC-type multidrug transporters: (i) the functional and structural similarities among these proteins in prokaryotic and eukaryotic cells, (ii) the molecular mechanism of these transporters, and (iii) their potential physiological role.
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Affiliation(s)
- H W van Veen
- Department of Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Kerklaan, The Netherlands.
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33
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Aono R, Ito M, Horikoshi K. Measurement of cytoplasmic pH of the alkaliphile Bacillus lentus C-125 with a fluorescent pH probe. Microbiology (Reading) 1997; 143:2531-2536. [DOI: 10.1099/00221287-143-8-2531] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Summary: A method was established to measure the cytoplasmic pH of the facultative alkaliphilic strain, Bacillus lentus C-125. The bacterium was loaded with a pH-sensitive fluorescent probe, 2′,7′-bis-(2-carboxyethyl)-5 (and -6)-carboxyfluorescein (BCECF), and cytoplasmic pH was determined from the intensity of fluorescence of the intracellular BCECF. The activity of the organism to maintain neutral cytoplasmic pH was assessed by measuring the cytoplasmic pH of the cells exposed to various pH conditions. The cytoplasmic pH maintenance activity of C-125 increased with increasing culture pH, indicating that the activity was regulated in response to the culture pH.
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Affiliation(s)
- Rikizo Aono
- Department of Bioengineering, Faculty of Bioscience and Biotechnology, Tokyo Institute of Technology, Nagatsuta 4259, Yokohama 226, Japan
| | - Masahiro Ito
- Department of Bioengineering, Faculty of Bioscience and Biotechnology, Tokyo Institute of Technology, Nagatsuta 4259, Yokohama 226, Japan
| | - Koki Horikoshi
- Department of Bioengineering, Faculty of Bioscience and Biotechnology, Tokyo Institute of Technology, Nagatsuta 4259, Yokohama 226, Japan
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Bolhuis H, van Veen HW, Poolman B, Driessen AJ, Konings WN. Mechanisms of multidrug transporters. FEMS Microbiol Rev 1997; 21:55-84. [PMID: 9299702 DOI: 10.1111/j.1574-6976.1997.tb00345.x] [Citation(s) in RCA: 130] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Drug resistance, mediated by various mechanisms, plays a crucial role in the failure of the drug-based treatment of various infectious diseases. As a result, these infectious diseases re-emerge rapidly and cause many victims every year. Another serious threat is imposed by the development of multidrug resistance (MDR) in eukaryotic (tumor) cells, where many different drugs fail to perform their therapeutic function. One of the causes of the occurrence of MDR in these cells is the action of transmembrane transport proteins that catalyze the active extrusion of a large number of structurally and functionally unrelated compounds out of the cell. The mode of action of these MDR transporters and their apparent lack of substrate specificity is poorly understood and has been subject to many speculations. In this review we will summarize our current knowledge about the occurrence, mechanism and molecular basis of (multi-)drug resistance especially as found in bacteria.
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Affiliation(s)
- H Bolhuis
- Department of Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Haren, The Netherlands
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35
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Abstract
Protein folding that is coupled to disulphide bond formation has many experimental advantages. In particular, the kinetic roles and importance of all the disulphide intermediates can be determined, usually unambiguously. This contrasts with other types of protein folding, where the roles of any intermediates detected are usually not established. Nevertheless, there is considerable confusion in the literature about even the best-characterized disulphide folding pathways. This article attempts to set the record straight.
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36
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Hop-resistant Lactobacillus brevis contains a novel plasmid harboring a multidrug resistance-like gene. ACTA ACUST UNITED AC 1997. [DOI: 10.1016/s0922-338x(97)82778-x] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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37
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Davey HM, Kell DB. Flow cytometry and cell sorting of heterogeneous microbial populations: the importance of single-cell analyses. Microbiol Rev 1996; 60:641-96. [PMID: 8987359 PMCID: PMC239459 DOI: 10.1128/mr.60.4.641-696.1996] [Citation(s) in RCA: 263] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The most fundamental questions such as whether a cell is alive, in the sense of being able to divide or to form a colony, may sometimes be very hard to answer, since even axenic microbial cultures are extremely heterogeneous. Analyses that seek to correlate such things as viability, which is a property of an individual cell, with macroscopic measurements of culture variables such as ATP content, respiratory activity, and so on, must inevitably fail. It is therefore necessary to make physiological measurements on individual cells. Flow cytometry is such a technique, which allows one to analyze cells rapidly and individually and permits the quantitative analysis of microbial heterogeneity. It therefore offers many advantages over conventional measurements for both routine and more exploratory analyses of microbial properties. While the technique has been widely applied to the study of mammalian cells, is use in microbiology has until recently been much more limited, largely because of the smaller size of microbes and the consequently smaller optical signals obtainable from them. Since these technical barriers no longer hold, flow cytometry with appropriate stains has been used for the rapid discrimination and identification of microbial cells, for the rapid assessment of viability and of the heterogeneous distributions of a wealth of other more detailed physiological properties, for the analysis of antimicrobial drug-cell interactions, and for the isolation of high-yielding strains of biotechnological interest. Flow cytometric analyses provide an abundance of multivariate data, and special methods have been devised to exploit these. Ongoing advances mean that modern flow cytometers may now be used by nonspecialists to effect a renaissance in our understanding of microbial heterogeneity.
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Affiliation(s)
- H M Davey
- Institute of Biological Sciences, University of Wales, Aberystwyth, Dyfed, United Kingdom
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38
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Bolhuis H, van Veen HW, Brands JR, Putman M, Poolman B, Driessen AJ, Konings WN. Energetics and mechanism of drug transport mediated by the lactococcal multidrug transporter LmrP. J Biol Chem 1996; 271:24123-8. [PMID: 8798651 DOI: 10.1074/jbc.271.39.24123] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The gene encoding the secondary multidrug transporter LmrP of Lactococcus lactis was heterologously expressed in Escherichia coli. The energetics and mechanism of drug extrusion mediated by LmrP were studied in membrane vesicles of E. coli. LmrP-mediated extrusion of tetraphenyl phosphonium (TPP+) from right-side-out membrane vesicles and uptake of the fluorescent membrane probe 1-[4-(trimethylamino)phenyl]-6-phenylhexa-1,3,5-triene (TMA-DPH) into inside-out membrane vesicles are driven by the membrane potential (Deltapsi) and the transmembrane proton gradient (DeltapH), pointing to an electrogenic drug/proton antiport mechanism. Ethidium bromide, a substrate for LmrP, inhibited the LmrP-mediated TPP+ extrusion from right-side-out membrane vesicles, showing that LmrP is capable of transporting structurally unrelated drugs. Kinetic analysis of LmrP-mediated TMA-DPH transport revealed a direct relation between the transport rate and the amount of TMA-DPH associated with the cytoplasmic leaflet of the lipid bilayer. This observation indicates that drugs are extruded from the inner leaflet of the cytoplasmic membrane into the external medium. This is the first report that shows that drug extrusion by a secondary multidrug resistance (MDR) transporter occurs by a "hydrophobic vacuum cleaner" mechanism in a similar way as was proposed for the primary lactococcal MDR transporter, LmrA.
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Affiliation(s)
- H Bolhuis
- Department of Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Kerklaan 30, NL-9751 NN Haren, The Netherlands
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39
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Glaasker E, Konings WN, Poolman B. The application of pH-sensitive fluorescent dyes in lactic acid bacteria reveals distinct extrusion systems for unmodified and conjugated dyes. Mol Membr Biol 1996; 13:173-81. [PMID: 8905646 DOI: 10.3109/09687689609160594] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Intracellular pH in bacteria can be measured efficiently between internal pH values of 6.5 and 8.5 with the fluorescent pH indicator 2',7'-bis-(2-carboxyethyl)-5[and-6]-carboxyfluorescein (BCECF). A new fluorescent pH probe with a lower pKa(app) than BCECF was synthesized from fluorescein isothiocyanate and glutamate. The new probe, N-(fluorescein thio-ureanyl)-glutamate (FTUG), was much less sensitive to changes in concentrations of KCl than was BCECF. Similar to BCECF, an efflux of FTUG independent of the proton motive force, but dependent on ATP, was observed both in Lactobacillus plantarum and Lactococcus lactis. Corrections for probe efflux allowed accurate measurements of the pHin. Similar intracellular pH values were determined with FTUG and BCECF, in the range where both probes can be applied, and the pH values correlated well with those estimated from the distribution of radio-labelled benzoic acid. Since FITC can easily be coupled to substrates containing an amino group, it is possible to develop other FITC derivatives as well. The mechanisms of probe excretion and the nature of the excreted product(s) were studied in further detail for BCECF and FTUG. BCECF was excreted from wild-type L. lactis in an unmodified form as was determined by chromatographic and mass spectrometry analysis. In the case of FTUG, the excreted product was a conjugated derivative. Unmodified FTUG was not excreted, although it was present in cellular extracts from L. lactis. Exit of BCECF was completely inhibited in a BCECF efflux mutant (Bef-) of L. lactis, whereas FTUG-conjugate efflux in this mutant was similar to the wild-type. Addition of indomethacin, a known inhibitor of BCECF efflux in human epithelial cells, resulted in complete inhibition of BCECF efflux in wild-type L. lactis, whereas FTUG-conjugate exit was only slightly affected. The results of the mutant and inhibitor studies suggest that FTUG-conjugate and BCECF efflux in L. lactis are mediated by different ATP-driven extrusion systems for organic anions.
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Affiliation(s)
- E Glaasker
- Department of Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Haren, The Netherlands
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40
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41
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Ratinaud MH, Revidon S. A flow cytometric method to assess functional state of the Listeria membrane. J Microbiol Methods 1996. [DOI: 10.1016/0167-7012(95)00086-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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42
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Chapter 8 Multidrug resistance in prokaryotes: Molecular mechanisms of drug efflux. ACTA ACUST UNITED AC 1996. [DOI: 10.1016/s1383-8121(96)80049-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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43
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Chikindas ML, Novák J, Driessen AJ, Konings WN, Schilling KM, Caufield PW. Mutacin II, a bactericidal antibiotic from Streptococcus mutans. Antimicrob Agents Chemother 1995; 39:2656-60. [PMID: 8592997 PMCID: PMC163007 DOI: 10.1128/aac.39.12.2656] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Mutacin II is an antibiotic that is produced by group II Streptococcus mutans. It inhibits the growth of other streptococci as well as many other gram-positive microorganisms by a hitherto unknown mechanism. Mutacin II possess bactericidal activity against susceptible cells. It transiently depolarizes the transmembrane electrical potential (delta psi) and the transmembrane pH gradient (delta pH) and partially inhibits amino acid transport. However, it rapidly depletes the intracellular ATP pool in glucose-energized cells and prevents the generation of ATP. It is concluded that mutacin II does not belong to the group of pore-forming antibiotics (type A) or to the type B antibiotics, which inhibit phospholipases or interfere with peptidoglycan biosynthesis. Mutacin II acts by inhibiting essential enzyme functions at the level of metabolic energy generation, an activity that has not yet been classified for antibiotics.
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44
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Ueckert J, Breeuwer P, Abee T, Stephens P, von Caron GN, ter Steeg PF. Flow cytometry applications in physiological study and detection of foodborne microorganisms. Int J Food Microbiol 1995; 28:317-26. [PMID: 8750676 DOI: 10.1016/0168-1605(95)00066-6] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- J Ueckert
- Unilever Research Laboratorium, Vlaardingen, The Netherlands
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45
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Bolhuis H, Poelarends G, van Veen HW, Poolman B, Driessen AJ, Konings WN. The Lactococcal lmrP gene encodes a proton motive force-dependent drug transporter. J Biol Chem 1995; 270:26092-8. [PMID: 7592810 DOI: 10.1074/jbc.270.44.26092] [Citation(s) in RCA: 91] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
To genetically dissect the drug extrusion systems of Lactococcus lactis, a chromosomal DNA library was made in Escherichia coli and recombinant strains were selected for resistance to high concentrations of ethidium bromide. Recombinant strains were found to be resistant not only to ethidium bromide but also to daunomycin and tetraphenylphosphonium. The drug resistance is conferred by the lmrP gene, which encodes a hydrophobic polypeptide of 408 amino acid residues with 12 putative membrane-spanning segments. Some sequence elements in this novel membrane protein share similarity to regions in the transposon Tn10-encoded tetracycline resistance determinant TetA, the multidrug transporter Bmr from Bacillus subtilis, and the bicyclomycin resistance determinant Bcr from E. coli. Drug resistance associated with lmrP expression correlated with energy-dependent extrusion of the molecules. Drug extrusion was inhibited by ionophores that dissipate the proton motive force but not by the ATPase inhibitor ortho-vanadate. These observations are indicative for a drug-proton antiport system. A lmrP deletion mutant was constructed via homologous recombinant using DNA fragments of the flanking region of the gene. The L. lactis (delta lmrP) strain exhibited residual ethidium extrusion activity, which in contrast to the parent strain was inhibited by ortho-vanadate. The results indicate that in the absence of the functional drug-proton anti-porter LmrP, L. lactis is able to overexpress another, ATP-dependent, drug extrusion system. These findings substantiate earlier studies on the isolation and characterization of drug-resistant mutants of L. lactis (Bolhuis, H., Molenaar, D., Poelarends, G., van Veen, H. W., Poolman, B., Driessen, A. J. M., and Konings, W. N. (1994) J. Bacteriol. 176, 6957-6964).
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Affiliation(s)
- H Bolhuis
- Department of Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Haren, The Netherlands
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46
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Oude Elferink RP, Meijer DK, Kuipers F, Jansen PL, Groen AK, Groothuis GM. Hepatobiliary secretion of organic compounds; molecular mechanisms of membrane transport. BIOCHIMICA ET BIOPHYSICA ACTA 1995; 1241:215-68. [PMID: 7640297 DOI: 10.1016/0304-4157(95)00006-d] [Citation(s) in RCA: 249] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- R P Oude Elferink
- Department of Gastrointestinal and Liver Diseases, Academic Medical Center, AZ Amsterdam, The Netherlands
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47
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Abstract
Microbial transformations of cyclic hydrocarbons have received much attention during the past three decades. Interest in the degradation of environmental pollutants as well as in applications of microorganisms in the catalysis of chemical reactions has stimulated research in this area. The metabolic pathways of various aromatics, cycloalkanes, and terpenes in different microorganisms have been elucidated, and the genetics of several of these routes have been clarified. The toxicity of these compounds to microorganisms is very important in the microbial degradation of hydrocarbons, but not many researchers have studied the mechanism of this toxic action. In this review, we present general ideas derived from the various reports mentioning toxic effects. Most importantly, lipophilic hydrocarbons accumulate in the membrane lipid bilayer, affecting the structural and functional properties of these membranes. As a result of accumulated hydrocarbon molecules, the membrane loses its integrity, and an increase in permeability to protons and ions has been observed in several instances. Consequently, dissipation of the proton motive force and impairment of intracellular pH homeostasis occur. In addition to the effects of lipophilic compounds on the lipid part of the membrane, proteins embedded in the membrane are affected. The effects on the membrane-embedded proteins probably result to a large extent from changes in the lipid environment; however, direct effects of lipophilic compounds on membrane proteins have also been observed. Finally, the effectiveness of changes in membrane lipid composition, modification of outer membrane lipopolysaccharide, altered cell wall constituents, and active excretion systems in reducing the membrane concentrations of lipophilic compounds is discussed. Also, the adaptations (e.g., increase in lipid ordering, change in lipid/protein ratio) that compensate for the changes in membrane structure are treated.
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Affiliation(s)
- J Sikkema
- Department of Food Science, Wageningen Agricultural University, The Netherlands
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48
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Abstract
Microbial transformations of cyclic hydrocarbons have received much attention during the past three decades. Interest in the degradation of environmental pollutants as well as in applications of microorganisms in the catalysis of chemical reactions has stimulated research in this area. The metabolic pathways of various aromatics, cycloalkanes, and terpenes in different microorganisms have been elucidated, and the genetics of several of these routes have been clarified. The toxicity of these compounds to microorganisms is very important in the microbial degradation of hydrocarbons, but not many researchers have studied the mechanism of this toxic action. In this review, we present general ideas derived from the various reports mentioning toxic effects. Most importantly, lipophilic hydrocarbons accumulate in the membrane lipid bilayer, affecting the structural and functional properties of these membranes. As a result of accumulated hydrocarbon molecules, the membrane loses its integrity, and an increase in permeability to protons and ions has been observed in several instances. Consequently, dissipation of the proton motive force and impairment of intracellular pH homeostasis occur. In addition to the effects of lipophilic compounds on the lipid part of the membrane, proteins embedded in the membrane are affected. The effects on the membrane-embedded proteins probably result to a large extent from changes in the lipid environment; however, direct effects of lipophilic compounds on membrane proteins have also been observed. Finally, the effectiveness of changes in membrane lipid composition, modification of outer membrane lipopolysaccharide, altered cell wall constituents, and active excretion systems in reducing the membrane concentrations of lipophilic compounds is discussed. Also, the adaptations (e.g., increase in lipid ordering, change in lipid/protein ratio) that compensate for the changes in membrane structure are treated.
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Affiliation(s)
- J Sikkema
- Department of Food Science, Wageningen Agricultural University, The Netherlands
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49
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Breeuwer P, Drocourt JL, Bunschoten N, Zwietering MH, Rombouts FM, Abee T. Characterization of uptake and hydrolysis of fluorescein diacetate and carboxyfluorescein diacetate by intracellular esterases in Saccharomyces cerevisiae, which result in accumulation of fluorescent product. Appl Environ Microbiol 1995; 61:1614-9. [PMID: 7747975 PMCID: PMC167417 DOI: 10.1128/aem.61.4.1614-1619.1995] [Citation(s) in RCA: 149] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Flow cytometry is a rapid and sensitive method which may be used for the detection of microorganisms in foods and drinks. A key requirement for this method is a sufficient fluorescence staining of the target cells. The mechanism of staining of the yeast Saccharomyces cerevisiae by fluorescein diacetate (FDA) and 5- (and 6-)carboxyfluorescein diacetate (cFDA) was studied in detail. The uptake rate of the prefluorochromes increased in direct proportion to the concentration and was not saturable, which suggests that transport occurs via a passive diffusion process. The permeability coefficient for cFDA was 1.3 x 10(-8) m s-1. Once inside the cell, the esters were hydrolyzed by intracellular esterases and their fluorescent products accumulated. FDA hydrolysis (at 40 degrees C) in cell extracts could be described by first-order reaction kinetics, and a rate constant (K) of 0.33 s-1 was calculated. Hydrolysis of cFDA (at 40 degrees C) in cell extracts was described by Michaelis-Menten kinetics with an apparent Vmax and Km of 12.3 nmol.min-1.mg of protein-1 and 0.29 mM, respectively. Accumulation of fluorescein was most likely limited by the esterase activity, since transport of FDA was faster than the hydrolysis rate. In contrast, accumulation of carboxyfluorescein was limited by the much slower transport of cFDA through the cell envelope. A simple mathematical model was developed to describe the fluorescence staining. The implications for optimal staining of yeast cells with FDA and cFDA are discussed.
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50
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Bolhuis H, Molenaar D, Poelarends G, van Veen HW, Poolman B, Driessen AJ, Konings WN. Proton motive force-driven and ATP-dependent drug extrusion systems in multidrug-resistant Lactococcus lactis. J Bacteriol 1994; 176:6957-64. [PMID: 7961458 PMCID: PMC197067 DOI: 10.1128/jb.176.22.6957-6964.1994] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Three mutants of Lactococcus lactis subsp. lactis MG1363, termed EthR, DauR, and RhoR, were selected for resistance to high concentrations of ethidium bromide, daunomycin, and rhodamine 6G, respectively. These mutants were found to be cross resistant to a number of structurally and functionally unrelated drugs, among which were typical substrates of the mammalian multidrug transporter (P-glycoprotein) such as daunomycin, quinine, actinomycin D, gramicidin D, and rhodamine 6G. The three multidrug-resistant strains showed an increased rate of energy-dependent ethidium and daunomycin efflux compared with that of the wild-type strain. This suggests that resistance to these toxic compounds is at least partly due to active efflux. Efflux of ethidium from the EthR strain could occur against a 37-fold inwardly directed concentration gradient. In all strains, ethidium efflux was inhibited by reserpine, a well-known inhibitor of P-glycoprotein. Ionophores which selectively dissipate the membrane potential or the pH gradient across the membrane inhibited ethidium and daunomycin efflux in the wild-type strain, corresponding with a proton motive force-driven efflux system. The ethidium efflux system in the EthR strain, on the other hand, was inhibited by ortho-vanadate and not upon dissipation of the proton motive force, which suggests the involvement of ATP in the energization of transport. The partial inhibition of ethidium efflux by ortho-vanadate and nigericin in the DauR and RhoR strains suggest that a proton motive force-dependent and an ATP-dependent system are expressed simultaneously. This is the first report of an ATP-dependent transport system in prokaryotes which confers multidrug resistance to the organism.
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Affiliation(s)
- H Bolhuis
- Department of Microbiology, University of Groningen, Haren, The Netherlands
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