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Auty JM, Jenkins CH, Hincks J, Straatman-Iwanowska AA, Allcock N, Turapov O, Galyov EE, Harding SV, Mukamolova GV. Generation of Distinct Differentially Culturable Forms of Burkholderia following Starvation at Low Temperature. Microbiol Spectr 2022; 10:e0211021. [PMID: 34985335 PMCID: PMC8729786 DOI: 10.1128/spectrum.02110-21] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Accepted: 12/04/2021] [Indexed: 11/20/2022] Open
Abstract
Bacteria have developed unique mechanisms to adapt to environmental stresses and challenges of the immune system. Here, we report that Burkholderia pseudomallei, the causative agent of melioidosis, and its laboratory surrogate, Burkholderia thailandensis, utilize distinct mechanisms for surviving starvation at different incubation temperatures. At 21°C, Burkholderia are present as short rods which can rapidly reactivate and form colonies on solid media. At 4°C, Burkholderia convert into coccoid forms that cannot be cultured on solid agar but can be resuscitated in liquid media supplemented with supernatant obtained from logarithmic phase cultures of B. thailandensis, or catalase and Tween 80, thus displaying characteristics of differentially culturable bacteria (DCB). These DCB have low intensity fluorescence when stained with SYTO 9, have an intact cell membrane (propidium iodide negative), and contain 16S rRNA at levels comparable with growing cells. We also present evidence that lytic transglycosylases, a family of peptidoglycan-remodeling enzymes, are involved in the generation of coccoid forms and their resuscitation to actively growing cells. A B. pseudomallei ΔltgGCFD mutant with four ltg genes deleted did not produce coccoid forms at 4°C and could not be resuscitated in the liquid media evaluated. Our findings provide insights into the adaptation of Burkholderia to nutrient limitation and the generation of differentially culturable bacteria. IMPORTANCE Bacterial pathogens exhibit physiologically distinct forms that enable their survival in an infected host, the environment and following exposure to antimicrobial agents. B. pseudomallei causes the disease melioidosis, which has a high mortality rate and is difficult to treat with antibiotics. The bacterium is endemic to several countries and detected in high abundance in the environment. Here, we report that during starvation at low temperature, B. pseudomallei produces coccoid forms that cannot grow in standard media and which, therefore, can be challenging to detect using common tools. We provide evidence that the formation of these cocci is mediated by cell wall-specialized enzymes and lytic transglycosylases, and that resuscitation of these forms occurs following the addition of catalase and Tween 80. Our findings have important implications for the disease control and detection of B. pseudomallei, an agent of both public health and defense interest.
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Affiliation(s)
- Joss M. Auty
- Department of Respiratory Sciences, University of Leicester, Leicester, United Kingdom
| | - Christopher H. Jenkins
- Defence Science and Technology Laboratory, Chemical, Biological and Radiological Division, Porton Down, Salisbury, Wiltshire, United Kingdom
| | - Jennifer Hincks
- FACS Facility Core Biotechnology Services, University of Leicester, Leicester, United Kingdom
| | - Anna A. Straatman-Iwanowska
- Electron Microscopy Facility, Core Biotechnology Services, University of Leicester, Leicester, United Kingdom
| | - Natalie Allcock
- Electron Microscopy Facility, Core Biotechnology Services, University of Leicester, Leicester, United Kingdom
| | - Obolbek Turapov
- Department of Respiratory Sciences, University of Leicester, Leicester, United Kingdom
| | - Edouard E. Galyov
- Department of Genetics and Genome Biology, University of Leicester, Leicester, United Kingdom
| | - Sarah V. Harding
- Department of Respiratory Sciences, University of Leicester, Leicester, United Kingdom
- Defence Science and Technology Laboratory, Chemical, Biological and Radiological Division, Porton Down, Salisbury, Wiltshire, United Kingdom
| | - Galina V. Mukamolova
- Department of Respiratory Sciences, University of Leicester, Leicester, United Kingdom
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Täuber S, Schmitz J, Blöbaum L, Fante N, Steinhoff H, Grünberger A. How to Perform a Microfluidic Cultivation Experiment—A Guideline to Success. BIOSENSORS 2021; 11:bios11120485. [PMID: 34940242 PMCID: PMC8699335 DOI: 10.3390/bios11120485] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 11/23/2021] [Accepted: 11/26/2021] [Indexed: 12/19/2022]
Abstract
As a result of the steadily ongoing development of microfluidic cultivation (MC) devices, a plethora of setups is used in biological laboratories for the cultivation and analysis of different organisms. Because of their biocompatibility and ease of fabrication, polydimethylsiloxane (PDMS)-glass-based devices are most prominent. Especially the successful and reproducible cultivation of cells in microfluidic systems, ranging from bacteria over algae and fungi to mammalians, is a fundamental step for further quantitative biological analysis. In combination with live-cell imaging, MC devices allow the cultivation of small cell clusters (or even single cells) under defined environmental conditions and with high spatio-temporal resolution. Yet, most setups in use are custom made and only few standardised setups are available, making trouble-free application and inter-laboratory transfer tricky. Therefore, we provide a guideline to overcome the most frequently occurring challenges during a MC experiment to allow untrained users to learn the application of continuous-flow-based MC devices. By giving a concise overview of the respective workflow, we give the reader a general understanding of the whole procedure and its most common pitfalls. Additionally, we complement the listing of challenges with solutions to overcome these hurdles. On selected case studies, covering successful and reproducible growth of cells in MC devices, we demonstrate detailed solutions to solve occurring challenges as a blueprint for further troubleshooting. Since developer and end-user of MC devices are often different persons, we believe that our guideline will help to enhance a broader applicability of MC in the field of life science and eventually promote the ongoing advancement of MC.
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Affiliation(s)
- Sarah Täuber
- Multiscale Bioengineering, Faculty of Technology, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany; (S.T.); (J.S.); (L.B.); (N.F.); (H.S.)
- Center for Biotechnology (CeBiTec), Bielefeld University, Universitätsstraße 27, 33615 Bielefeld, Germany
| | - Julian Schmitz
- Multiscale Bioengineering, Faculty of Technology, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany; (S.T.); (J.S.); (L.B.); (N.F.); (H.S.)
- Center for Biotechnology (CeBiTec), Bielefeld University, Universitätsstraße 27, 33615 Bielefeld, Germany
| | - Luisa Blöbaum
- Multiscale Bioengineering, Faculty of Technology, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany; (S.T.); (J.S.); (L.B.); (N.F.); (H.S.)
- Center for Biotechnology (CeBiTec), Bielefeld University, Universitätsstraße 27, 33615 Bielefeld, Germany
| | - Niklas Fante
- Multiscale Bioengineering, Faculty of Technology, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany; (S.T.); (J.S.); (L.B.); (N.F.); (H.S.)
| | - Heiko Steinhoff
- Multiscale Bioengineering, Faculty of Technology, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany; (S.T.); (J.S.); (L.B.); (N.F.); (H.S.)
- Center for Biotechnology (CeBiTec), Bielefeld University, Universitätsstraße 27, 33615 Bielefeld, Germany
| | - Alexander Grünberger
- Multiscale Bioengineering, Faculty of Technology, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany; (S.T.); (J.S.); (L.B.); (N.F.); (H.S.)
- Center for Biotechnology (CeBiTec), Bielefeld University, Universitätsstraße 27, 33615 Bielefeld, Germany
- Correspondence:
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Dong K, Pan H, Yang D, Rao L, Zhao L, Wang Y, Liao X. Induction, detection, formation, and resuscitation of viable but non‐culturable state microorganisms. Compr Rev Food Sci Food Saf 2019; 19:149-183. [DOI: 10.1111/1541-4337.12513] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 10/21/2019] [Accepted: 11/14/2019] [Indexed: 01/05/2023]
Affiliation(s)
- Kai Dong
- Beijing Advanced Innovation Center for Food Nutrition and Human HealthCollege of Food Science and Nutritional EngineeringChina Agricultural University Beijing China
- College of Food Science and Nutritional EngineeringChina Agricultural University Beijing China
- Key Lab of Fruit and Vegetable ProcessingMinistry of Agriculture and Rural Affairs Beijing China
| | - Hanxu Pan
- Beijing Advanced Innovation Center for Food Nutrition and Human HealthCollege of Food Science and Nutritional EngineeringChina Agricultural University Beijing China
- College of Food Science and Nutritional EngineeringChina Agricultural University Beijing China
- Key Lab of Fruit and Vegetable ProcessingMinistry of Agriculture and Rural Affairs Beijing China
| | - Dong Yang
- Beijing Advanced Innovation Center for Food Nutrition and Human HealthCollege of Food Science and Nutritional EngineeringChina Agricultural University Beijing China
- College of Food Science and Nutritional EngineeringChina Agricultural University Beijing China
- Key Lab of Fruit and Vegetable ProcessingMinistry of Agriculture and Rural Affairs Beijing China
| | - Lei Rao
- Beijing Advanced Innovation Center for Food Nutrition and Human HealthCollege of Food Science and Nutritional EngineeringChina Agricultural University Beijing China
- College of Food Science and Nutritional EngineeringChina Agricultural University Beijing China
- Key Lab of Fruit and Vegetable ProcessingMinistry of Agriculture and Rural Affairs Beijing China
| | - Liang Zhao
- College of Food Science and Nutritional EngineeringChina Agricultural University Beijing China
- Key Lab of Fruit and Vegetable ProcessingMinistry of Agriculture and Rural Affairs Beijing China
| | - Yongtao Wang
- College of Food Science and Nutritional EngineeringChina Agricultural University Beijing China
- Key Lab of Fruit and Vegetable ProcessingMinistry of Agriculture and Rural Affairs Beijing China
| | - Xiaojun Liao
- Beijing Advanced Innovation Center for Food Nutrition and Human HealthCollege of Food Science and Nutritional EngineeringChina Agricultural University Beijing China
- College of Food Science and Nutritional EngineeringChina Agricultural University Beijing China
- Key Lab of Fruit and Vegetable ProcessingMinistry of Agriculture and Rural Affairs Beijing China
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Richter LV, Mansfeldt CB, Kuan MM, Cesare AE, Menefee ST, Richardson RE, Ahner BA. Altered Microbiome Leads to Significant Phenotypic and Transcriptomic Differences in a Lipid Accumulating Chlorophyte. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:6854-6863. [PMID: 29750518 DOI: 10.1021/acs.est.7b06581] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Given the challenges facing the economically favorable production of products from microalgae, understanding factors that might impact productivity rates including growth rates and accumulation of desired products, for example, triacylglycerols (TAG) for biodiesel feedstock, remains critical. Although operational parameters such as media composition and reactor design can clearly effect growth rates, the role of microbe-microbe interactions is just beginning to be elucidated. In this study an oleaginous marine algae Chlorella spp. C596 culture is shown to be better described as a microbial community. Perturbations to this microbial community showed a significant impact on phenotypes including sustained differences in growth rate and TAG accumulation of 2.4 and 2.5 fold, respectively. Characterization of the associated community using Illumina 16S rRNA amplicon and random shotgun transcriptomic analyses showed that the fast growth rate correlated with two specific bacterial species ( Ruegeria and Rhodobacter spp). The transcriptomic response of the Chlorella species revealed that the slower growing algal consortium C596-S1 upregulated genes associated with photosynthesis and resource scavenging and decreased the expression of genes associated with transcription and translation relative to the initial C596-R1. Our studies advance the appreciation of the effects microbiomes can have on algal growth in bioreactors and suggest that symbiotic interactions are involved in a range of critical processes including nitrogen, carbon cycling, and oxidative stress.
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Affiliation(s)
- Lubna V Richter
- Department of Biological and Environmental Engineering , Cornell University , Ithaca , New York 14853 , United States
| | - Cresten B Mansfeldt
- School of Civil and Environmental Engineering , Cornell University , Ithaca , New York 14853 , United States
| | - Michael M Kuan
- Department of Biological and Environmental Engineering , Cornell University , Ithaca , New York 14853 , United States
| | - Alexandra E Cesare
- Department of Biological and Environmental Engineering , Cornell University , Ithaca , New York 14853 , United States
| | - Stephen T Menefee
- Department of Biological and Environmental Engineering , Cornell University , Ithaca , New York 14853 , United States
| | - Ruth E Richardson
- School of Civil and Environmental Engineering , Cornell University , Ithaca , New York 14853 , United States
| | - Beth A Ahner
- Department of Biological and Environmental Engineering , Cornell University , Ithaca , New York 14853 , United States
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Ungphakorn W, Lagerbäck P, Nielsen EI, Tängdén T. Automated time-lapse microscopy a novel method for screening of antibiotic combination effects against multidrug-resistant Gram-negative bacteria. Clin Microbiol Infect 2017; 24:778.e7-778.e14. [PMID: 29108951 DOI: 10.1016/j.cmi.2017.10.029] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 09/28/2017] [Accepted: 10/31/2017] [Indexed: 02/02/2023]
Abstract
OBJECTIVES Antibiotic combinations are often used for carbapenemase-producing Enterobacteriaceae (CPE) but more data are needed on the optimal selection of drugs. This study aimed to evaluate the feasibility of a novel automated method based on time-lapse microscopy (the oCelloScope, Philips BioCell A/S, Allerød, Denmark) to determine in vitro combination effects against CPE and to discuss advantages and limitations of the oCelloScope in relation to standard methods. METHODS Four Klebsiella pneumoniae and two Escherichia coli were exposed to colistin, meropenem, rifampin and tigecycline, alone and in combination. In the oCelloScope experiments, a background corrected absorption (BCA) value of ≤8 at 24 h was used as a primary cut-off indicating inhibition of bacterial growth. A new approach was used to determine synergy, indifference and antagonism based on the number of objects (bacteria) in the images. Static time-kill experiments were performed for comparison. RESULTS The time-kill experiments showed synergy with 12 of 36 regimens, most frequently with colistin plus rifampin. BCA values ≤8 consistently correlated with 24-h bacterial concentrations ≤6 log10 CFU/mL. The classification of combination effects agreed with the time-kill results for 33 of 36 regimens. In three cases, the interactions could not be classified with the microscopy method because of low object counts. CONCLUSIONS Automated time-lapse microscopy can accurately determine the effects of antibiotic combinations. The novel method is highly efficient compared with time-kill experiments, more informative than checkerboards and can be useful to accelerate the screening for combinations active against multidrug-resistant Gram-negative bacteria.
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Affiliation(s)
- W Ungphakorn
- Department of Medical Sciences, Uppsala University, Uppsala, Sweden
| | - P Lagerbäck
- Department of Medical Sciences, Uppsala University, Uppsala, Sweden
| | - E I Nielsen
- Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
| | - T Tängdén
- Department of Medical Sciences, Uppsala University, Uppsala, Sweden.
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Gómez-Govea MA, García S, Heredia N. Bacterial metabolites from intra- and inter-species influencing thermotolerance: the case of Bacillus cereus and Geobacillus stearothermophilus. Folia Microbiol (Praha) 2016; 62:183-189. [PMID: 27896600 DOI: 10.1007/s12223-016-0487-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Accepted: 11/23/2016] [Indexed: 11/29/2022]
Abstract
Bacterial metabolites with communicative functions could provide protection against stress conditions to members of the same species. Yet, information remains limited about protection provided by metabolites in Bacillus cereus and inter-species. This study investigated the effect of extracellular compounds derived from heat shocked (HS) and non-HS cultures of B. cereus and Geobacillus stearothermophilus on the thermotolerance of non-HS vegetative and sporulating B. cereus. Cultures of B. cereus and G. stearothermophilus were subjected to HS (42 or 65 °C respectively for 30 min) or non-HS treatments. Cells and supernatants were separated, mixed in a combined array, and then exposed to 50 °C for 60 min and viable cells determined. For spores, D values (85 and 95 °C) were evaluated after 120 h. In most cases, supernatants from HS B. cereus cultures added to non-HS B. cereus cells caused their thermotolerance to increase (D 50 12.2-51.9) when compared to supernatants from non-HS cultures (D 50 7.4-21.7). While the addition of supernatants from HS and non-HS G. stearothermophilus cultures caused the thermotolerance of non-HS cells from B. cereus to decrease initially (D 50 3.7-7.1), a subsequent increase was detected in most cases (D 50 18-97.7). In most cases, supernatants from sporulating G. stearothermophilus added to sporulating cells of B. cereus caused the thermotolerance of B. cereus 4810 spores to decline, whereas that of B. cereus 14579 increased. This study clearly shows that metabolites in supernatants from either the same or different species (such as G. stearothermophilus) influence the thermotolerance of B. cereus.
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Affiliation(s)
- Mayra Alejandra Gómez-Govea
- Universidad Autónoma de Nuevo León, Facultad de Ciencias Biológicas, Laboratorio de Bioquímica y Genética de Microorganismos, Ciudad Universitaria, 66455, San Nicolás de los Garza, N.L, Mexico
| | - Santos García
- Universidad Autónoma de Nuevo León, Facultad de Ciencias Biológicas, Laboratorio de Bioquímica y Genética de Microorganismos, Ciudad Universitaria, 66455, San Nicolás de los Garza, N.L, Mexico
| | - Norma Heredia
- Universidad Autónoma de Nuevo León, Facultad de Ciencias Biológicas, Laboratorio de Bioquímica y Genética de Microorganismos, Ciudad Universitaria, 66455, San Nicolás de los Garza, N.L, Mexico.
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7
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Ungphakorn W, Malmberg C, Lagerbäck P, Cars O, Nielsen EI, Tängdén T. Evaluation of automated time-lapse microscopy for assessment of in vitro activity of antibiotics. J Microbiol Methods 2016; 132:69-75. [PMID: 27836633 DOI: 10.1016/j.mimet.2016.11.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Revised: 11/03/2016] [Accepted: 11/03/2016] [Indexed: 11/17/2022]
Abstract
This study aimed to evaluate the potential of a new time-lapse microscopy based method (oCelloScope) to efficiently assess the in vitro antibacterial effects of antibiotics. Two E. coli and one P. aeruginosa strain were exposed to ciprofloxacin, colistin, ertapenem and meropenem in 24-h experiments. Background corrected absorption (BCA) derived from the oCelloScope was used to detect bacterial growth. The data obtained with the oCelloScope were compared with those of the automated Bioscreen C method and standard time-kill experiments and a good agreement in results was observed during 6-24h of experiments. Viable counts obtained at 1, 4, 6 and 24h during oCelloScope and Bioscreen C experiments were well correlated with the corresponding BCA and optical density (OD) data. Initial antibacterial effects during the first 6h of experiments were difficult to detect with the automated methods due to their high detection limits (approximately 105CFU/mL for oCelloScope and 107CFU/mL for Bioscreen C), the inability to distinguish between live and dead bacteria and early morphological changes of bacteria during exposure to ciprofloxacin, ertapenem and meropenem. Regrowth was more frequently detected in time-kill experiments, possibly related to the larger working volume with an increased risk of pre-existing or emerging resistance. In comparison with Bioscreen C, the oCelloScope provided additional information on bacterial growth dynamics in the range of 105 to 107CFU/mL and morphological features. In conclusion, the oCelloScope would be suitable for detection of in vitro effects of antibiotics, especially when a large number of regimens need to be tested.
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Affiliation(s)
- Wanchana Ungphakorn
- Department of Medical Sciences, Section of Infectious Diseases, Uppsala University, Uppsala, Sweden; Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
| | - Christer Malmberg
- Department of Medical Sciences, Section of Infectious Diseases, Uppsala University, Uppsala, Sweden
| | - Pernilla Lagerbäck
- Department of Medical Sciences, Section of Infectious Diseases, Uppsala University, Uppsala, Sweden
| | - Otto Cars
- Department of Medical Sciences, Section of Infectious Diseases, Uppsala University, Uppsala, Sweden
| | - Elisabet I Nielsen
- Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
| | - Thomas Tängdén
- Department of Medical Sciences, Section of Infectious Diseases, Uppsala University, Uppsala, Sweden.
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Calo JR, Park SH, Baker CA, Ricke SC. Specificity of Salmonella Typhimurium strain (ATCC 14028) growth responses to Salmonella serovar-generated spent media. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART. B, PESTICIDES, FOOD CONTAMINANTS, AND AGRICULTURAL WASTES 2015; 50:422-429. [PMID: 25844864 DOI: 10.1080/03601234.2015.1011962] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Salmonella enterica is one of the most prevalent pathogens responsible for foodborne illness worldwide. Numerous Salmonella serovars have been associated with the consumption of a variety of products, and limiting food-borne illness due to Salmonella serovars is a continuing problem for food producers and public health. The emergence and prevalence of Salmonella serovars has been studied but the predominant serovars have varied somewhat over the years. The aims of this research were to compare the aerobic growth responses of selected predominant foodborne Salmonella serovars, and evaluate how the spent media from different serovars affects the growth of a well-characterized Salmonella Typhimurium strain. Growth responses were similar for most strains in spent media except for S. Typhimurium (ATCC 14028), which exhibited a decrease in growth in the presence of Salmonella Heidelberg (ARI-14) spent media. This research will provide a better understanding of the growth differences among several Salmonella serovars in nutrient limited spent media.
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Affiliation(s)
- Juliany Rivera Calo
- a Center for Food Safety and Department of Food Science , University of Arkansas , Fayetteville , Arkansas , USA
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Li L, Mendis N, Trigui H, Oliver JD, Faucher SP. The importance of the viable but non-culturable state in human bacterial pathogens. Front Microbiol 2014; 5:258. [PMID: 24917854 PMCID: PMC4040921 DOI: 10.3389/fmicb.2014.00258] [Citation(s) in RCA: 553] [Impact Index Per Article: 55.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Accepted: 05/12/2014] [Indexed: 12/12/2022] Open
Abstract
Many bacterial species have been found to exist in a viable but non-culturable (VBNC) state since its discovery in 1982. VBNC cells are characterized by a loss of culturability on routine agar, which impairs their detection by conventional plate count techniques. This leads to an underestimation of total viable cells in environmental or clinical samples, and thus poses a risk to public health. In this review, we present recent findings on the VBNC state of human bacterial pathogens. The characteristics of VBNC cells, including the similarities and differences to viable, culturable cells and dead cells, and different detection methods are discussed. Exposure to various stresses can induce the VBNC state, and VBNC cells may be resuscitated back to culturable cells under suitable stimuli. The conditions that trigger the induction of the VBNC state and resuscitation from it are summarized and the mechanisms underlying these two processes are discussed. Last but not least, the significance of VBNC cells and their potential influence on human health are also reviewed.
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Affiliation(s)
- Laam Li
- Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University Ste-Anne-de-Bellevue, QC, Canada
| | - Nilmini Mendis
- Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University Ste-Anne-de-Bellevue, QC, Canada
| | - Hana Trigui
- Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University Ste-Anne-de-Bellevue, QC, Canada
| | - James D Oliver
- Department of Biology, University of North Carolina at Charlotte Charlotte, NC, USA
| | - Sebastien P Faucher
- Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University Ste-Anne-de-Bellevue, QC, Canada
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Calidas D, Lyon H, Culver GM. The N-terminal extension of S12 influences small ribosomal subunit assembly in Escherichia coli. RNA (NEW YORK, N.Y.) 2014; 20:321-30. [PMID: 24442609 PMCID: PMC3923127 DOI: 10.1261/rna.042432.113] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
The small subunit (SSU) of the ribosome of E. coli consists of a core of ribosomal RNA (rRNA) surrounded peripherally by ribosomal proteins (r-proteins). Ten of the 15 universally conserved SSU r-proteins possess nonglobular regions called extensions. The N-terminal noncanonically structured extension of S12 traverses from the solvent to intersubunit surface of the SSU and is followed by a more C-terminal globular region that is adjacent to the decoding center of the SSU. The role of the globular region in maintaining translational fidelity is well characterized, but a role for the S12 extension in SSU structure and function is unknown. We examined the effect of stepwise truncation of the extension of S12 in SSU assembly and function in vitro and in vivo. Examination of in vitro assembly in the presence of sequential N-terminal truncated variants of S12 reveals that N-terminal deletions of greater than nine amino acids exhibit decreased tRNA-binding activity and altered 16S rRNA architecture particularly in the platform of the SSU. While wild-type S12 expressed from a plasmid can rescue a genomic deletion of the essential gene for S12, rpsl; N-terminal deletions of S12 exhibit deleterious phenotypic consequences. Partial N-terminal deletions of S12 are slow growing and cold sensitive. Strains bearing these truncations as the sole copy of S12 have increased levels of free SSUs and immature 16S rRNA as compared with the wild-type S12. These differences are hallmarks of SSU biogenesis defects, indicating that the extension of S12 plays an important role in SSU assembly.
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Affiliation(s)
- Deepika Calidas
- Department of Biology, Center for RNA Biology: From Genome to Therapeutics, University of Rochester Medical Center, Rochester, New York 14627, USA
| | - Hiram Lyon
- Department of Biology, Center for RNA Biology: From Genome to Therapeutics, University of Rochester Medical Center, Rochester, New York 14627, USA
| | - Gloria M. Culver
- Department of Biology, Center for RNA Biology: From Genome to Therapeutics, University of Rochester Medical Center, Rochester, New York 14627, USA
- Corresponding authorE-mail
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Madar D, Dekel E, Bren A, Zimmer A, Porat Z, Alon U. Promoter activity dynamics in the lag phase of Escherichia coli. BMC SYSTEMS BIOLOGY 2013; 7:136. [PMID: 24378036 PMCID: PMC3918108 DOI: 10.1186/1752-0509-7-136] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Accepted: 11/21/2013] [Indexed: 11/25/2022]
Abstract
Background Lag phase is a period of time with no growth that occurs when stationary phase bacteria are transferred to a fresh medium. Bacteria in lag phase seem inert: their biomass does not increase. The low number of cells and low metabolic activity make it difficult to study this phase. As a consequence, it has not been studied as thoroughly as other bacterial growth phases. However, lag phase has important implications for bacterial infections and food safety. We asked which, if any, genes are expressed in the lag phase of Escherichia coli, and what is their dynamic expression pattern. Results We developed an assay based on imaging flow cytometry of fluorescent reporter cells that overcomes the challenges inherent in studying lag phase. We distinguish between lag1 phase- in which there is no biomass growth, and lag2 phase- in which there is biomass growth but no cell division. We find that in lag1 phase, most promoters are not active, except for the enzymes that utilize the specific carbon source in the medium. These genes show promoter activities that increase exponentially with time, despite the fact that the cells do not measurably increase in size. An oxidative stress promoter, katG, is also active. When cells enter lag2 and begin to grow in size, they switch to a full growth program of promoter activity including ribosomal and metabolic genes. Conclusions The observed exponential increase in enzymes for the specific carbon source followed by an abrupt switch to production of general growth genes is a solution of an optimal control model, known as bang-bang control. The present approach contributes to the understanding of lag phase, the least studied of bacterial growth phases.
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Affiliation(s)
| | | | | | | | | | - Uri Alon
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel.
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Pinto D, Santos MA, Chambel L. Thirty years of viable but nonculturable state research: unsolved molecular mechanisms. Crit Rev Microbiol 2013; 41:61-76. [PMID: 23848175 DOI: 10.3109/1040841x.2013.794127] [Citation(s) in RCA: 211] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Viable but nonculturable (VBNC) cells were recognized 30 years ago; and despite decades of research on the topic, most results are disperse and apparently incongruous. Since its description, a huge controversy arose regarding the ecological significance of this state: is it a degradation process without real significance for bacterial life cycles or is it an adaptive strategy of bacteria to cope with stressful conditions? In order to solve the molecular mechanisms of VBNC state induction and resuscitation, researchers in the field must be aware and overcome common issues delaying research progress. In this review, we discuss the intrinsic characteristic features of VBNC cells, the first clues on what is behind the VBNC state's induction, the models proposed for their resuscitation and the current methods to prove not only that cells are in VBNC state but also that they are able to resuscitate.
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Affiliation(s)
- Daniela Pinto
- Center for Biodiversity, Functional and Integrative Genomics (BioFIG), Faculty of Sciences, University of Lisbon , Lisbon , Portugal
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13
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Affiliation(s)
- Melissa Ivey
- Department of Food, Bioprocessing, and Nutrition Sciences, North Carolina State University, Raleigh, North Carolina 27695
| | - Mara Massel
- Department of Food, Bioprocessing, and Nutrition Sciences, North Carolina State University, Raleigh, North Carolina 27695
| | - Trevor G. Phister
- Division of Food Science, Brewing Science Program, School of Biological Sciences, University of Nottingham, Sutton Bonington LE12 5RD, United Kingdom;
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14
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Williams HE, Steele JCP, Clements MO, Keshavarz T. γ-Heptalactone is an endogenously produced quorum-sensing molecule regulating growth and secondary metabolite production by Aspergillus nidulans. Appl Microbiol Biotechnol 2012; 96:773-81. [DOI: 10.1007/s00253-012-4065-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2012] [Revised: 03/28/2012] [Accepted: 03/29/2012] [Indexed: 11/24/2022]
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15
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Pin C, Rolfe MD, Muñoz-Cuevas M, Hinton JCD, Peck MW, Walton NJ, Baranyi J. Network analysis of the transcriptional pattern of young and old cells of Escherichia coli during lag phase. BMC SYSTEMS BIOLOGY 2009; 3:108. [PMID: 19917103 PMCID: PMC2780417 DOI: 10.1186/1752-0509-3-108] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/15/2009] [Accepted: 11/16/2009] [Indexed: 11/18/2022]
Abstract
Background The aging process of bacteria in stationary phase is halted if cells are subcultured and enter lag phase and it is then followed by cellular division. Network science has been applied to analyse the transcriptional response, during lag phase, of bacterial cells starved previously in stationary phase for 1 day (young cells) and 16 days (old cells). Results A genome scale network was constructed for E. coli K-12 by connecting genes with operons, transcription and sigma factors, metabolic pathways and cell functional categories. Most of the transcriptional changes were detected immediately upon entering lag phase and were maintained throughout this period. The lag period was longer for older cells and the analysis of the transcriptome revealed different intracellular activity in young and old cells. The number of genes differentially expressed was smaller in old cells (186) than in young cells (467). Relatively, few genes (62) were up- or down-regulated in both cultures. Transcription of genes related to osmotolerance, acid resistance, oxidative stress and adaptation to other stresses was down-regulated in both young and old cells. Regarding carbohydrate metabolism, genes related to the citrate cycle were up-regulated in young cells while old cells up-regulated the Entner Doudoroff and gluconate pathways and down-regulated the pentose phosphate pathway. In both old and young cells, anaerobic respiration and fermentation pathways were down-regulated, but only young cells up-regulated aerobic respiration while there was no evidence of aerobic respiration in old cells. Numerous genes related to DNA maintenance and replication, translation, ribosomal biosynthesis and RNA processing as well as biosynthesis of the cell envelope and flagellum and several components of the chemotaxis signal transduction complex were up-regulated only in young cells. The genes for several transport proteins for iron compounds were up-regulated in both young and old cells. Numerous genes encoding transporters for carbohydrates and organic alcohols and acids were down-regulated in old cells only. Conclusion Network analysis revealed very different transcriptional activities during the lag period in old and young cells. Rejuvenation seems to take place during exponential growth by replicative dilution of old cellular components.
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Affiliation(s)
- Carmen Pin
- Institute of Food Research, Norwich NR4 7UA, UK.
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16
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Brehm-Stecher B, Young C, Jaykus LA, Tortorello ML. Sample preparation: the forgotten beginning. J Food Prot 2009; 72:1774-89. [PMID: 19722419 DOI: 10.4315/0362-028x-72.8.1774] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Advances in molecular technologies and automated instrumentation have provided many opportunities for improved detection and identification of microorganisms; however, the upstream sample preparation steps needed to apply these advances to foods have not been adequately researched or developed. Thus, the extent to which these advances have improved food microbiology has been limited. The purpose of this review is to present the current state of sample preparation, to identify knowledge gaps and opportunities for improvement, and to recognize the need to support greater research and development efforts on preparative methods in food microbiology. The discussion focuses on the need to push technological developments toward methods that do not rely on enrichment culture. Among the four functional components of microbiological analysis (i.e., sampling, separation, concentration, detection), the separation and concentration components need to be researched more extensively to achieve rapid, direct, and quantitative methods. The usefulness of borrowing concepts of separation and concentration from other disciplines and the need to regard the microorganism as a physicochemical analyte that may be directly extracted from the food matrix are discussed. The development of next-generation systems that holistically integrate sample preparation with rapid, automated detection will require interdisciplinary collaboration and substantially increased funding.
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Affiliation(s)
- Byron Brehm-Stecher
- Department of Food Science and Human Nutrition, Iowa State University, Ames, Iowa 50011, USA
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17
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Heredia N, Ybarra P, Hernández C, García S. Extracellular protectants produced byClostridium perfringenscells at elevated temperatures. Lett Appl Microbiol 2009; 48:133-9. [DOI: 10.1111/j.1472-765x.2008.02504.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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18
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Garton NJ, Waddell SJ, Sherratt AL, Lee SM, Smith RJ, Senner C, Hinds J, Rajakumar K, Adegbola RA, Besra GS, Butcher PD, Barer MR. Cytological and transcript analyses reveal fat and lazy persister-like bacilli in tuberculous sputum. PLoS Med 2008; 5:e75. [PMID: 18384229 PMCID: PMC2276522 DOI: 10.1371/journal.pmed.0050075] [Citation(s) in RCA: 313] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/24/2007] [Accepted: 02/14/2008] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Tuberculous sputum provides a sample of bacilli that must be eliminated by chemotherapy and that may go on to transmit infection. A preliminary observation that Mycobacterium tuberculosis cells contain triacylglycerol lipid bodies in sputum, but not when growing in vitro, led us to investigate the extent of this phenomenon and its physiological basis. METHODS AND FINDINGS Microscopy-positive sputum samples from the UK and The Gambia were investigated for their content of lipid body-positive mycobacteria by combined Nile red and auramine staining. All samples contained a lipid body-positive population varying from 3% to 86% of the acid-fast bacilli present. The recent finding that triacylglycerol synthase is expressed by mycobacteria when they enter in vitro nonreplicating persistence led us to investigate whether this state was also associated with lipid body formation. We found that, when placed in laboratory conditions inducing nonreplicating persistence, two M. tuberculosis strains had lipid body levels comparable to those found in sputum. We investigated these physiological findings further by comparing the M. tuberculosis transcriptome of growing and nonreplicating persistence cultures with that obtained directly from sputum samples. Although sputum has traditionally been thought to contain actively growing tubercle bacilli, our transcript analyses refute the hypothesis that these cells predominate. Rather, they reinforce the results of the lipid body analyses by revealing transcriptional signatures that can be clearly attributed to slowly replicating or nonreplicating mycobacteria. Finally, the lipid body count was highly correlated (R(2) = 0.64, p < 0.03) with time to positivity in diagnostic liquid cultures, thereby establishing a direct link between this cytological feature and the size of a potential nonreplicating population. CONCLUSION As nonreplicating tubercle bacilli are tolerant to the cidal action of antibiotics and resistant to multiple stresses, identification of this persister-like population of tubercle bacilli in sputum presents exciting and tractable new opportunities to investigate both responses to chemotherapy and the transmission of tuberculosis.
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Affiliation(s)
- Natalie J Garton
- Department of Infection, Immunity and Inflammation, University of Leicester Medical School, Leicester, United Kingdom
| | - Simon J Waddell
- Medical Microbiology, Division of Cellular and Molecular Medicine, St George's University of London, London, United Kingdom
| | - Anna L Sherratt
- Department of Infection, Immunity and Inflammation, University of Leicester Medical School, Leicester, United Kingdom
| | - Su-Min Lee
- Department of Infection, Immunity and Inflammation, University of Leicester Medical School, Leicester, United Kingdom
| | - Rebecca J Smith
- Department of Infection, Immunity and Inflammation, University of Leicester Medical School, Leicester, United Kingdom
| | - Claire Senner
- Medical Microbiology, Division of Cellular and Molecular Medicine, St George's University of London, London, United Kingdom
| | - Jason Hinds
- Medical Microbiology, Division of Cellular and Molecular Medicine, St George's University of London, London, United Kingdom
| | - Kumar Rajakumar
- Department of Infection, Immunity and Inflammation, University of Leicester Medical School, Leicester, United Kingdom
- Department of Clinical Microbiology, University Hospitals of Leicester National Health Service Trust, Leicester, United Kingdom
| | | | - Gurdyal S Besra
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Philip D Butcher
- Medical Microbiology, Division of Cellular and Molecular Medicine, St George's University of London, London, United Kingdom
- * To whom correspondence should be addressed. E-mail: (PDB); (MRB)
| | - Michael R Barer
- Department of Infection, Immunity and Inflammation, University of Leicester Medical School, Leicester, United Kingdom
- Department of Clinical Microbiology, University Hospitals of Leicester National Health Service Trust, Leicester, United Kingdom
- * To whom correspondence should be addressed. E-mail: (PDB); (MRB)
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20
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Kell DB, Brown M, Davey HM, Dunn WB, Spasic I, Oliver SG. Metabolic footprinting and systems biology: the medium is the message. Nat Rev Microbiol 2005; 3:557-65. [PMID: 15953932 DOI: 10.1038/nrmicro1177] [Citation(s) in RCA: 261] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
One element of classical systems analysis treats a system as a black or grey box, the inner structure and behaviour of which can be analysed and modelled by varying an internal or external condition, probing it from outside and studying the effect of the variation on the external observables. The result is an understanding of the inner make-up and workings of the system. The equivalent of this in biology is to observe what a cell or system excretes under controlled conditions - the 'metabolic footprint' or exometabolome - as this is readily and accurately measurable. Here, we review the principles, experimental approaches and scientific outcomes that have been obtained with this useful and convenient strategy.
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Affiliation(s)
- Douglas B Kell
- School of Chemistry, University of Manchester, Faraday Building, PO Box 88, Sackville Street, Manchester M60 1QD, UK.
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Chen H, Fujita M, Feng Q, Clardy J, Fink GR. Tyrosol is a quorum-sensing molecule in Candida albicans. Proc Natl Acad Sci U S A 2004; 101:5048-52. [PMID: 15051880 PMCID: PMC387371 DOI: 10.1073/pnas.0401416101] [Citation(s) in RCA: 313] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The human fungal pathogen Candida albicans shows a significant lag in growth when diluted into fresh minimal medium. This lag is abolished by the addition of conditioned medium from a high-density culture. The active component of conditioned medium is tyrosol, which is released into the medium continuously during growth. Under conditions permissive for germ-tube formation, tyrosol stimulates the formation of these filamentous protrusions. Because germ-tube formation is inhibited by farnesol, another quorum-sensing molecule, this process must be under complex positive and negative control by environmental conditions. The identification of tyrosol as an autoregulatory molecule has important implications on the dynamics of growth and morphogenesis in Candida.
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Affiliation(s)
- Hao Chen
- Whitehead Institute for Biomedical Research, Nine Cambridge Center, Cambridge, MA 02142, USA
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Taylor-Robinson JD, Child M, Pickup R, Strike P, Edwards C. Cell-cell interactions influence resistance and survival of Salmonella serotype Typhimurium to environmental stress. J Appl Microbiol 2003; 94:95-102. [PMID: 12492929 DOI: 10.1046/j.1365-2672.2003.01808.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
AIMS The aim of this work was to study the effects of prolonged nutrient stress on survival, cell interactions and resistance to inimical processes in Salmonella serotype Typhimurium. METHODS AND RESULTS Salmonella Typhimurium cells were subjected to prolonged incubation in the stationary phase of growth and the properties of starved cells (old) were investigated with reference to those of exponentially-growing cells (young). Competition experiments between old and young cells revealed cell-cell interactions that influenced stationary phase survival and response of the bacterium to heat stress. During prolonged incubation of cells, cycles of resistance and sensitivity to heat stress were identified. Competition experiments between old and young cells revealed that the resistance of young cells to heat increased to levels more like those of stationary phase cells than growing cells. The presence of old cells influenced the phenotype of young cells, possibly by means of cell-cell interactions. There was no evidence for the involvement of any extracellularly-produced factors in this phenomenon, but a requirement that the old competitor cells be viable could be demonstrated. CONCLUSIONS It is proposed that the complex interactions within stationary phase cultures of Salm. Typhimurium may be due to cycles of mutation in concert with an as yet undefined interaction between old cells and growing ones. SIGNIFICANCE AND IMPACT OF THE STUDY This study provides evidence for active and diverse responses to nutrient stress within populations of Salm. Typhimurium that promote survival and that may be important for the success of this bacterium as a pathogen.
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Carbonell X, Corchero JL, Cubarsí R, Vila P, Villaverde A. Control of Escherichia coli growth rate through cell density. Microbiol Res 2003; 157:257-65. [PMID: 12501989 DOI: 10.1078/0944-5013-00167] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The transition from the exponential to the stationary phase of Escherichia coli cultures has been investigated regarding nutrient availability. This analysis strongly suggests that the declining of the cell division rate is not caused by mere nutrient limitation but also by an immediate sensing of cell concentration. In addition, both the growth rate and the final biomass achieved by a batch culture can be manipulated by altering its density during the early exponential phase. This result, which has been confirmed by using different experimental approaches, supports the hypothesis that the E. coli quorum sensing is not only determined by the release of soluble cell-to-cell communicators. Cell-associated sensing elements might also be involved in modulating the bacterial growth even in the presence of non-limiting (although declining) nutrient concentrations, thus promoting their economical utilisation in dense populations.
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Affiliation(s)
- Xavier Carbonell
- Institut de Biotecnologia i de Biomedicina and Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, Bellaterra 08193 Barcelona, Spain
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24
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Mukamolova GV, Kaprelyants AS, Kell DB, Young M. Adoption of the transiently non-culturable state — a bacterial survival strategy? Adv Microb Physiol 2003; 47:65-129. [PMID: 14560663 DOI: 10.1016/s0065-2911(03)47002-1] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Microbial culturability can be ephemeral. Cells are not merely either dead or alive but can adopt physiological states in which they appear to be (transiently) non-culturable under conditions in which they are known normally to be able to grow and divide. The reacquisition of culturability from such states is referred to as resuscitation. We here develop the idea that this "transient non-culturability" is a consequence of a special survival strategy, and summarise the morphological, physiological and genetic evidence underpinning such behaviour and its adaptive significance.
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Affiliation(s)
- Galina V Mukamolova
- Institute of Biological Sciences, University of Wales, Aberystwyth, Ceredigion SY23 3DD, UK
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25
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DeLisa MP, Bentley WE. Bacterial autoinduction: looking outside the cell for new metabolic engineering targets. Microb Cell Fact 2002; 1:5. [PMID: 12537600 PMCID: PMC149432 DOI: 10.1186/1475-2859-1-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2002] [Accepted: 12/20/2002] [Indexed: 01/29/2023] Open
Abstract
Recent evidence has demonstrated that cell-to-cell signaling is a fundamental activity carried out by numerous microorganisms. A number of specialized processes are reported to be regulated by density-dependent signaling molecules including antibiotic production, bioluminescence, biofilm formation, genetic competence, sporulation, swarming motility and virulence. However, a more centralized role for quorum sensing is emerging where quorum signaling pathways overlap with stress and starvation circuits to regulate cellular adaptation to changing environmental conditions. The interplay of these phenomena is especially critical in the expression of recombinant proteins where elicitation of stress responses can dramatically impact cellular productivity.
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Affiliation(s)
- Matthew P DeLisa
- Department of Chemical Engineering, University of Texas, Austin, Texas, USA 78712
- new address: School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York, USA 14853
| | - William E Bentley
- Center for Biosystems Research, University of Maryland Biotechnology Institute, Baltimore, Maryland, USA 20742
- Department of Chemical Engineering, University of Maryland, College Park, Maryland, USA 20742
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