1
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Trunet C, Vischer N, Coroller L, Brul S. Germination and outgrowth of Bacillus mycoides KBAB4 spores are impacted by environmental pH, quantitatively analyzed at single cell level with sporetracker. Food Microbiol 2024; 121:104509. [PMID: 38637073 DOI: 10.1016/j.fm.2024.104509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Revised: 02/06/2024] [Accepted: 02/24/2024] [Indexed: 04/20/2024]
Abstract
Quantifying spore germination and outgrowth heterogeneity is challenging. Single cell level analysis should provide supplementary knowledge regarding the impact of unfavorable conditions on germination and outgrowth dynamics. This work aimed to quantify the impact of pH on spore germination and outgrowth, investigating the behavior of individual spore crops, produced under optimal and suboptimal conditions. Bacillus mycoides (formerly B. weihenstephanensis) KBAB4 spores, produced at pH 7.4 and at pH 5.5 were incubated at different pH values, from pH 5.2 to 7.4. The spores were monitored by microscopy live imaging, in controlled conditions, at 30 °C. The images were analyzed using SporeTracker, to determine the state of single cells. The impact of pH on germination and outgrowth times and rates was estimated and the correlation between these parameters was quantified. The correlation between germination and outgrowth times was significantly higher at low pH. These results suggest that an environmental pressure highlights the heterogeneity of spore germination and outgrowth within a spore population. Results were consistent with previous observations at population level, now confirmed and extended to single cell level. Therefore, single cell level analyses can be used to quantify the heterogeneity of spore populations, which is of interest in order to control the development of spore-forming bacteria, responsible for food safety issues.
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Affiliation(s)
- C Trunet
- Univ Brest, INRAE, Laboratoire Universitaire de Biodiversité et Écologie Microbienne, F-29000, Quimper, France.
| | - N Vischer
- Laboratory for Molecular Biology and Microbial Food Safety, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, the Netherlands
| | - L Coroller
- Univ Brest, INRAE, Laboratoire Universitaire de Biodiversité et Écologie Microbienne, F-29000, Quimper, France
| | - S Brul
- Laboratory for Molecular Biology and Microbial Food Safety, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, the Netherlands
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2
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Gautham AK, Miner LE, Franco MN, Thornquist SC, Crickmore MA. Dopamine biases decisions by limiting temporal integration. Nature 2024; 632:850-857. [PMID: 39085606 DOI: 10.1038/s41586-024-07749-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Accepted: 06/24/2024] [Indexed: 08/02/2024]
Abstract
Motivations bias our responses to stimuli, producing behavioural outcomes that match our needs and goals. Here we describe a mechanism behind this phenomenon: adjusting the time over which stimulus-derived information is permitted to accumulate towards a decision. As a Drosophila copulation progresses, the male becomes less likely to continue mating through challenges1-3. We show that a set of copulation decision neurons (CDNs) flexibly integrates information about competing drives to mediate this decision. Early in mating, dopamine signalling restricts CDN integration time by potentiating Ca2+/calmodulin-dependent protein kinase II (CaMKII) activation in response to stimulatory inputs, imposing a high threshold for changing behaviours. Later into mating, the timescale over which the CDNs integrate termination-promoting information expands, increasing the likelihood of switching behaviours. We suggest scalable windows of temporal integration at dedicated circuit nodes as a key but underappreciated variable in state-based decision-making.
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Affiliation(s)
- Aditya K Gautham
- F. M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Lauren E Miner
- F. M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Marco N Franco
- F. M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Stephen C Thornquist
- F. M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.
- Laboratory of Integrative Brain Function, The Rockefeller University, New York, NY, USA.
| | - Michael A Crickmore
- F. M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.
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3
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Gautham AK, Miner LE, Franco MN, Thornquist SC, Crickmore MA. Molecular control of temporal integration matches decision-making to motivational state. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.01.582988. [PMID: 38496671 PMCID: PMC10942309 DOI: 10.1101/2024.03.01.582988] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
Motivations bias our responses to stimuli, producing behavioral outcomes that match our needs and goals. We describe a mechanism behind this phenomenon: adjusting the time over which stimulus-derived information is permitted to accumulate toward a decision. As a Drosophila copulation progresses, the male becomes less likely to continue mating through challenges. We show that a set of Copulation Decision Neurons (CDNs) flexibly integrates information about competing drives to mediate this decision. Early in mating, dopamine signaling restricts CDN integration time by potentiating CaMKII activation in response to stimulatory inputs, imposing a high threshold for changing behaviors. Later into mating, the timescale over which the CDNs integrate termination-promoting information expands, increasing the likelihood of switching behaviors. We suggest scalable windows of temporal integration at dedicated circuit nodes as a key but underappreciated variable in state-based decision-making.
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Affiliation(s)
- Aditya K. Gautham
- FM Kirby Neurobiology Center, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115
| | - Lauren E. Miner
- FM Kirby Neurobiology Center, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115
| | - Marco N. Franco
- FM Kirby Neurobiology Center, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115
| | | | - Michael A. Crickmore
- FM Kirby Neurobiology Center, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115
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4
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Li YQ, He L, Aryal M, Wicander J, Korza G, Setlow P. Thioflavin-T does not report on electrochemical potential and memory of dormant or germinating bacterial spores. mBio 2023; 14:e0222023. [PMID: 37830807 PMCID: PMC10653816 DOI: 10.1128/mbio.02220-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Accepted: 08/24/2023] [Indexed: 10/14/2023] Open
Abstract
IMPORTANCE Bacillus and Clostridium spores cause food spoilage and disease because of spores' dormancy and resistance to microbicides. However, when spores "come back to life" in germination, their resistance properties are lost. Thus, understanding the mechanisms of spore germination could facilitate the development of "germinate to eradicate" strategies. One germination feature is the memory of a pulsed germinant stimulus leading to greater germination following a second pulse. Recent observations of increases in spore binding of the potentiometric dye thioflavin-T early in their germination of spores led to the suggestion that increasing electrochemical potential is how spores "remember" germinant pulses. However, new work finds no increased thioflavin-T binding in the physiological germination of Coatless spores or of intact spores germinating with dodecylamine, even though spore memory is seen in both cases. Thus, using thioflavin-T uptake by germinating spores to assess the involvement of electrochemical potential in memory of germinant exposure, as suggested recently, is questionable.
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Affiliation(s)
- Yong-qing Li
- School of Electrical Engineering and Intelligentization, Dongguan University of Technology, Dongguan, Guangdong, China
- Department of Physics, East Carolina University, Greenville, North Carolina, USA
| | - Lin He
- School of Electrical Engineering and Intelligentization, Dongguan University of Technology, Dongguan, Guangdong, China
| | - Makunda Aryal
- Department of Physics, East Carolina University, Greenville, North Carolina, USA
| | - James Wicander
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, Connecticut, USA
| | - George Korza
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, Connecticut, USA
| | - Peter Setlow
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, Connecticut, USA
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5
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Gao Y, Amon JD, Artzi L, Ramírez-Guadiana FH, Brock KP, Cofsky JC, Marks DS, Kruse AC, Rudner DZ. Bacterial spore germination receptors are nutrient-gated ion channels. Science 2023; 380:387-391. [PMID: 37104613 PMCID: PMC11154005 DOI: 10.1126/science.adg9829] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Accepted: 03/29/2023] [Indexed: 04/29/2023]
Abstract
Bacterial spores resist antibiotics and sterilization and can remain metabolically inactive for decades, but they can rapidly germinate and resume growth in response to nutrients. Broadly conserved receptors embedded in the spore membrane detect nutrients, but how spores transduce these signals remains unclear. Here, we found that these receptors form oligomeric membrane channels. Mutations predicted to widen the channel initiated germination in the absence of nutrients, whereas those that narrow it prevented ion release and germination in response to nutrients. Expressing receptors with widened channels during vegetative growth caused loss of membrane potential and cell death, whereas the addition of germinants to cells expressing wild-type receptors triggered membrane depolarization. Therefore, germinant receptors act as nutrient-gated ion channels such that ion release initiates exit from dormancy.
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Affiliation(s)
- Yongqiang Gao
- Department of Microbiology, Harvard Medical ScF(2hool, 77 Avenue Louis Pasteur, Boston MA 02115
| | - Jeremy D. Amon
- Department of Microbiology, Harvard Medical ScF(2hool, 77 Avenue Louis Pasteur, Boston MA 02115
- Present Address: Moderna Genomics, 200 Technology Square, Cambridge MA 02139
| | - Lior Artzi
- Department of Microbiology, Harvard Medical ScF(2hool, 77 Avenue Louis Pasteur, Boston MA 02115
- Present Address: Evolved By Nature, 196 Boston Ave, Medford MA 02155
| | | | - Kelly P. Brock
- Department of Systems Biology, Harvard Medical School, 200 Longwood Avenue, Boston MA 02115
- Present Address: Kernal Biologics, 238 Main Street, Cambrdige MA 02142
| | - Joshua C. Cofsky
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 250 Longwood Avenue, Boston MA 02115
| | - Deborah S. Marks
- Department of Systems Biology, Harvard Medical School, 200 Longwood Avenue, Boston MA 02115
| | - Andrew C. Kruse
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 250 Longwood Avenue, Boston MA 02115
| | - David Z. Rudner
- Department of Microbiology, Harvard Medical ScF(2hool, 77 Avenue Louis Pasteur, Boston MA 02115
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6
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Kikuchi K, Galera-Laporta L, Weatherwax C, Lam JY, Moon EC, Theodorakis EA, Garcia-Ojalvo J, Süel GM. Electrochemical potential enables dormant spores to integrate environmental signals. Science 2022; 378:43-49. [PMID: 36201591 PMCID: PMC10593254 DOI: 10.1126/science.abl7484] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/13/2023]
Abstract
The dormant state of bacterial spores is generally thought to be devoid of biological activity. We show that despite continued dormancy, spores can integrate environmental signals over time through a preexisting electrochemical potential. Specifically, we studied thousands of individual Bacillus subtilis spores that remain dormant when exposed to transient nutrient pulses. Guided by a mathematical model of bacterial electrophysiology, we modulated the decision to exit dormancy by genetically and chemically targeting potassium ion flux. We confirmed that short nutrient pulses result in step-like changes in the electrochemical potential of persistent spores. During dormancy, spores thus gradually release their stored electrochemical potential to integrate extracellular information over time. These findings reveal a decision-making mechanism that operates in physiologically inactive cells.
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Affiliation(s)
- Kaito Kikuchi
- Molecular Biology Section, Division of Biological Sciences, University of California San Diego; La Jolla, CA 92093, USA
| | - Leticia Galera-Laporta
- Molecular Biology Section, Division of Biological Sciences, University of California San Diego; La Jolla, CA 92093, USA
| | - Colleen Weatherwax
- Molecular Biology Section, Division of Biological Sciences, University of California San Diego; La Jolla, CA 92093, USA
| | - Jamie Y Lam
- Department of Chemistry and Biochemistry, University of California San Diego; La Jolla, CA 92093, USA
| | - Eun Chae Moon
- Molecular Biology Section, Division of Biological Sciences, University of California San Diego; La Jolla, CA 92093, USA
| | - Emmanuel A Theodorakis
- Department of Chemistry and Biochemistry, University of California San Diego; La Jolla, CA 92093, USA
| | - Jordi Garcia-Ojalvo
- Department of Medicine and Life Sciences, Universitat Pompeu Fabra; 08003 Barcelona, Spain
- Senior author
| | - Gürol M Süel
- Molecular Biology Section, Division of Biological Sciences, University of California San Diego; La Jolla, CA 92093, USA
- San Diego Center for Systems Biology, University of California San Diego; La Jolla, CA 92093-0380, USA
- Center for Microbiome Innovation, University of California San Diego; La Jolla, CA 92093-0380, USA
- Senior author
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7
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Christie G, Setlow P. Bacillus spore germination: Knowns, unknowns and what we need to learn. Cell Signal 2020; 74:109729. [PMID: 32721540 DOI: 10.1016/j.cellsig.2020.109729] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 07/18/2020] [Accepted: 07/21/2020] [Indexed: 01/06/2023]
Abstract
How might a microbial cell that is entirely metabolically dormant - and which has the ability to remain so for extended periods of time - irreversibly commit itself to resuming vegetative growth within seconds of being exposed to certain amino acids or sugars? That this process takes place in the absence of any detectable ATP or de novo protein synthesis, and relies upon a pre-formed apparatus that is immobilised, respectively, in a semi-crystalline membrane or multi-layered proteinaceous coat, only exacerbates the challenge facing spores of Bacillales species when stimulated to germinate. Whereas the process by which spores are formed in response to nutrient starvation - sporulation - involves the orchestrated interplay between hundreds of distinct proteins, the process by which spores return to life - germination - is a much simpler affair, requiring a handful of receptor and channel proteins complemented with specialized peptidoglycan lysins. Despite this relative simplicity, and research effort spanning many decades, comprehensive understanding of key molecular and biochemical details and, in particular signal transduction mechanisms associated with spore germination, has remained elusive. In this review we provide an up to date overview of the field while identifying what we consider to be the key gaps in knowledge associated with germination of Bacillales spores, suggesting also technical approaches that may provide fresh insight to this unique biological process.
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Affiliation(s)
- Graham Christie
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 OAS, United Kingdom.
| | - Peter Setlow
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, CT 06030-3305, USA.
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8
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Pickering DS, Vernon JJ, Freeman J, Wilcox MH, Chilton CH. Investigating the transient and persistent effects of heat on Clostridium difficile spores. J Med Microbiol 2019; 68:1445-1454. [PMID: 31429817 DOI: 10.1099/jmm.0.001048] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Purpose. Clostridium difficile spores are extremely resilient to high temperatures. Sublethal temperatures are associated with the 'reactivation' of dormant spores, and are utilized to maximize C. difficile spore recovery. Spore eradication is of vital importance to the food industry. The current study seeks to elucidate the transient and persisting effects of heating C. difficile spores at various temperatures.Methods. Spores of five C. difficile strains of different ribotypes (001, 015, 020, 027 and 078) were heated at 50, 60 and 70-80 °C for 60 min in phosphate-buffered saline (PBS) and enumerated at 0, 15, 30, 45 and 60 min. GInaFiT was used to model the kinetics of spore inactivation. In subsequent experiments, spores were transferred to enriched brain heart infusion (BHI) broths after 10 min of 80 °C heat treatment in PBS; samples were enumerated at 90 min and 24 h.Results. The spores of all strains demonstrated log-linear inactivation with tailing when heated for 60 min at 80 °C [(x̄=7.54±0.04 log10 vs 4.72±0.09 log10 colony-forming units (c.f.u.) ml- 1; P<0.001]. At 70 °C, all strains except 078 exhibited substantial decline in recovery over 60 min. Interestingly, 50 °C heat treatment had an inhibitory effect on 078 spore recovery at 0 vs 60 min (7.61±0.06 log10 c.f.u. ml- 1 vs 6.13±0.05 log10 c.f.u. ml- 1; P<0.001). Heating at 70/80 °C inhibited the initial germination and outgrowth of both newly produced and aged spores in enriched broths. This inhibition appeared to be transient; after 24 h vegetative counts were higher in heat-treated vs non-heat-treated spores (x̄=7.65±0.04 log10 c.f.u. ml- 1 vs 6.79±0.06 log10 c.f.u. ml- 1; P<0.001).Conclusions. The 078 spores were more resistant to the inhibitory effects of higher temperatures. Heat initially inhibits spore germination, but the subsequent outgrowth of vegetative populations accelerates after the initial inhibitory period.
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Affiliation(s)
- D S Pickering
- Healthcare Associated Infections Research Group, Leeds Institute for Biomedical and Clinical Sciences, University of Leeds, West Yorkshire, UK
| | - J J Vernon
- Healthcare Associated Infections Research Group, Leeds Institute for Biomedical and Clinical Sciences, University of Leeds, West Yorkshire, UK
| | - J Freeman
- Microbiology, Leeds Teaching Hospitals Trust, Leeds, UK
| | - M H Wilcox
- Microbiology, Leeds Teaching Hospitals Trust, Leeds, UK.,Healthcare Associated Infections Research Group, Leeds Institute for Biomedical and Clinical Sciences, University of Leeds, West Yorkshire, UK
| | - C H Chilton
- Healthcare Associated Infections Research Group, Leeds Institute for Biomedical and Clinical Sciences, University of Leeds, West Yorkshire, UK
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9
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Virmani R, Sajid A, Singhal A, Gaur M, Joshi J, Bothra A, Garg R, Misra R, Singh VP, Molle V, Goel AK, Singh A, Kalia VC, Lee JK, Hasija Y, Arora G, Singh Y. The Ser/Thr protein kinase PrkC imprints phenotypic memory in Bacillus anthracis spores by phosphorylating the glycolytic enzyme enolase. J Biol Chem 2019; 294:8930-8941. [PMID: 30952697 DOI: 10.1074/jbc.ra118.005424] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2018] [Revised: 02/18/2019] [Indexed: 01/05/2023] Open
Abstract
Bacillus anthracis is the causative agent of anthrax in humans, bovine, and other animals. B. anthracis pathogenesis requires differentiation of dormant spores into vegetative cells. The spores inherit cellular components as phenotypic memory from the parent cell, and this memory plays a critical role in facilitating the spores' revival. Because metabolism initiates at the beginning of spore germination, here we metabolically reprogrammed B. anthracis cells to understand the role of glycolytic enzymes in this process. We show that increased expression of enolase (Eno) in the sporulating mother cell decreases germination efficiency. Eno is phosphorylated by the conserved Ser/Thr protein kinase PrkC which decreases the catalytic activity of Eno. We found that phosphorylation also regulates Eno expression and localization, thereby controlling the overall spore germination process. Using MS analysis, we identified the sites of phosphorylation in Eno, and substitution(s) of selected phosphorylation sites helped establish the functional correlation between phosphorylation and Eno activity. We propose that PrkC-mediated regulation of Eno may help sporulating B. anthracis cells in adapting to nutrient deprivation. In summary, to the best of our knowledge, our study provides the first evidence that in sporulating B. anthracis, PrkC imprints phenotypic memory that facilitates the germination process.
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Affiliation(s)
- Richa Virmani
- From the Department of Zoology, University of Delhi, Delhi 110007, India.,Council of Scientific and Industrial Research (CSIR)-Institute of Genomics and Integrative Biology, Delhi 110007, India.,Delhi Technological University, Delhi 110042, India
| | - Andaleeb Sajid
- Council of Scientific and Industrial Research (CSIR)-Institute of Genomics and Integrative Biology, Delhi 110007, India
| | - Anshika Singhal
- Council of Scientific and Industrial Research (CSIR)-Institute of Genomics and Integrative Biology, Delhi 110007, India
| | - Mohita Gaur
- From the Department of Zoology, University of Delhi, Delhi 110007, India
| | - Jayadev Joshi
- Council of Scientific and Industrial Research (CSIR)-Institute of Genomics and Integrative Biology, Delhi 110007, India
| | - Ankur Bothra
- Council of Scientific and Industrial Research (CSIR)-Institute of Genomics and Integrative Biology, Delhi 110007, India
| | - Richa Garg
- Council of Scientific and Industrial Research (CSIR)-Institute of Genomics and Integrative Biology, Delhi 110007, India
| | - Richa Misra
- From the Department of Zoology, University of Delhi, Delhi 110007, India.,Sri Venkateswara College, University of Delhi, Delhi 110021, India
| | - Vijay Pal Singh
- Council of Scientific and Industrial Research (CSIR)-Institute of Genomics and Integrative Biology, Delhi 110007, India
| | - Virginie Molle
- Dynamique des Interactions Membranaires Normales et Pathologiques (DIMNP), CNRS, University of Montpellier, Montpellier 34000, France
| | - Ajay K Goel
- Defence Research and Development Establishment, Gwalior 474002, India
| | - Archana Singh
- Council of Scientific and Industrial Research (CSIR)-Institute of Genomics and Integrative Biology, Delhi 110007, India
| | - Vipin C Kalia
- Department of Chemical Engineering, Konkuk University, 1 Hwayang-Dong, Gwangjin-Gu, Seoul 05029, Republic of Korea, and
| | - Jung-Kul Lee
- Department of Chemical Engineering, Konkuk University, 1 Hwayang-Dong, Gwangjin-Gu, Seoul 05029, Republic of Korea, and
| | - Yasha Hasija
- Delhi Technological University, Delhi 110042, India
| | - Gunjan Arora
- From the Department of Zoology, University of Delhi, Delhi 110007, India, .,Laboratory of Immunogenetics, NIAID, National Institutes of Health, Rockville, Maryland 20851
| | - Yogendra Singh
- From the Department of Zoology, University of Delhi, Delhi 110007, India, .,Council of Scientific and Industrial Research (CSIR)-Institute of Genomics and Integrative Biology, Delhi 110007, India
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10
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Abhyankar WR, Wen J, Swarge BN, Tu Z, de Boer R, Smelt JPPM, de Koning LJ, Manders E, de Koster CG, Brul S. Proteomics and microscopy tools for the study of antimicrobial resistance and germination mechanisms of bacterial spores. Food Microbiol 2018; 81:89-96. [PMID: 30910091 DOI: 10.1016/j.fm.2018.03.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Revised: 02/21/2018] [Accepted: 03/13/2018] [Indexed: 10/17/2022]
Abstract
Bacterial spores are ubiquitous in nature and can withstand both chemical and physical stresses. Spores can survive food preservation processes and upon outgrowth cause food spoilage as well as safety risks. The heterogeneous germination and outgrowth behavior of isogenic spore populations exacerbates this risk. A major unknown factor of spores is likely to be the inherently heterogeneous spore protein composition. The proteomics methods discussed here help in broadening the knowledge about spore structure and identification of putative target proteins from spores of different spore formers. Approaches to synchronize Bacillus subtilis spore formation, and to analyze spore proteins as well as the physiology of spore germination and outgrowth are also discussed. Live-imaging and fluorescence microscopy techniques discussed here allow analysis, at single cell level, of the 'germinosome', the process of spore germination itself, spore outgrowth and the spore intracellular pH dynamics. For the latter, a recently published improved pHluorin (IpHluorin) under control of the ptsG promoter is applicable. While the data obtained from such tools offers novel insight in the mechanisms of bacterial spore awakening, it may also be used to probe candidate antimicrobial compounds for inhibitory effects on spore germination and strengthen microbial risk assessment.
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Affiliation(s)
- W R Abhyankar
- Department of Molecular Biology and Microbial Food Safety, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands; Department of Mass Spectrometry of Bio-macromolecules, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - J Wen
- Department of Molecular Biology and Microbial Food Safety, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands; Van Leeuwenhoek Centre for Advanced Microscopy, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - B N Swarge
- Department of Molecular Biology and Microbial Food Safety, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands; Department of Mass Spectrometry of Bio-macromolecules, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - Z Tu
- Department of Molecular Biology and Microbial Food Safety, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands; Department of Mass Spectrometry of Bio-macromolecules, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - R de Boer
- Department of Molecular Biology and Microbial Food Safety, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - J P P M Smelt
- Department of Molecular Biology and Microbial Food Safety, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - L J de Koning
- Department of Mass Spectrometry of Bio-macromolecules, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - E Manders
- Van Leeuwenhoek Centre for Advanced Microscopy, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - C G de Koster
- Department of Mass Spectrometry of Bio-macromolecules, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - S Brul
- Department of Molecular Biology and Microbial Food Safety, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands.
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11
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Wang S, Brunt J, Peck MW, Setlow P, Li YQ. Analysis of the Germination of Individual Clostridium sporogenes Spores with and without Germinant Receptors and Cortex-Lytic Enzymes. Front Microbiol 2017; 8:2047. [PMID: 29118741 PMCID: PMC5661016 DOI: 10.3389/fmicb.2017.02047] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Accepted: 10/06/2017] [Indexed: 12/05/2022] Open
Abstract
The Gram-positive spore-forming anaerobe Clostridium sporogenes is a significant cause of food spoilage, and it is also used as a surrogate for C. botulinum spores for testing the efficacy of commercial sterilization. C. sporogenes spores have also been proposed as a vector to deliver drugs to tumor cells for cancer treatments. Such an application of C. sporogenes spores requires their germination and return to life. In this study, Raman spectroscopy and differential interference contrast (DIC) microscopy were used to analyze the germination kinetics of multiple individual C. sporogenes wild-type and germination mutant spores. Most individual C. sporogenes spores germinated with L-alanine began slow leakage of ∼5% of their large Ca-dipicolinic acid (CaDPA) depot at T1, all transitioned to rapid CaDPA release at Tlag1, completed CaDPA release at Trelease, and finished peptidoglycan cortex hydrolysis at Tlys. T1, Tlag1, Trelease, and Tlys times for individual spores were heterogeneous, but ΔTrelease (Trelease – Tlag1) periods were relatively constant. However, variability in T1 (or Tlag1) times appeared to be the major reason for the heterogeneity between individual spores in their germination times. After Trelease, some spores also displayed another lag in rate of change in DIC image intensity before the start of a second obvious DIC image intensity decline of 25–30% at Tlag2 prior to Tlys. This has not been seen with spores of other species. Almost all C. sporogenes spores lacking the cortex-lytic enzyme (CLE) CwlJ spores exhibited a Tlag2 in L-alanine germination. Sublethal heat treatment potentiated C. sporogenes spore germination with L-alanine, primarily by shortening T1 times. Spores without the CLEs SleB or CwlJ exhibited greatly slowed germination with L-alanine, but spores lacking all germinant receptor proteins did not germinate with L-alanine. The absence of these various germination proteins also decreased but did not abolish germination with the non-GR-dependent germinants dodecylamine and CaDPA, but spores without CwlJ exhibited no germination with CaDPA. Finally, C. sporogenes spores displayed commitment in germination, but memory in GR-dependent germination was small, and less than the memory in Bacillus spore germination.
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Affiliation(s)
- Shiwei Wang
- School of Chemical Engineering and Energy Technology, Dongguan University of Technology, Dongguan, China
| | - Jason Brunt
- Gut Health and Food Safety, Quadram Institute Bioscience, Norwich, United Kingdom
| | - Michael W Peck
- Gut Health and Food Safety, Quadram Institute Bioscience, Norwich, United Kingdom
| | - Peter Setlow
- Department of Molecular Biology and Biophysics, University of Connecticut Health Center, Farmington, CT, United States
| | - Yong-Qing Li
- School of Electronic Engineering, Dongguan University of Technology, Dongguan, China.,Department of Physics, East Carolina University, Greenville, NC, United States
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Abstract
Dormant Bacillales and Clostridiales spores begin to grow when small molecules (germinants) trigger germination, potentially leading to food spoilage or disease. Germination-specific proteins sense germinants, transport small molecules, and hydrolyze specific bonds in cortex peptidoglycan and specific proteins. Major events in germination include (a) germinant sensing; (b) commitment to germinate; (c) release of spores' depot of dipicolinic acid (DPA); (d) hydrolysis of spores' peptidoglycan cortex; and (e) spore core swelling and water uptake, cell wall peptidoglycan remodeling, and restoration of core protein and inner spore membrane lipid mobility. Germination is similar between Bacillales and Clostridiales, but some species differ in how germinants are sensed and how cortex hydrolysis and DPA release are triggered. Despite detailed knowledge of the proteins and signal transduction pathways involved in germination, precisely what some germination proteins do and how they do it remain unclear.
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Affiliation(s)
- Peter Setlow
- Molecular Biology and Biophysics, UConn Health, Farmington, Connecticut 06030-3305;
| | - Shiwei Wang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China;
| | - Yong-Qing Li
- Department of Physics, East Carolina University, Greenville, North Carolina 27858-4353;
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Spore Heat Activation Requirements and Germination Responses Correlate with Sequences of Germinant Receptors and with the Presence of a Specific spoVA2mob Operon in Foodborne Strains of Bacillus subtilis. Appl Environ Microbiol 2017; 83:AEM.03122-16. [PMID: 28130296 DOI: 10.1128/aem.03122-16] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2016] [Accepted: 01/21/2017] [Indexed: 01/19/2023] Open
Abstract
Spore heat resistance, germination, and outgrowth are problematic bacterial properties compromising food safety and quality. Large interstrain variation in these properties makes prediction and control of spore behavior challenging. High-level heat resistance and slow germination of spores of some natural Bacillus subtilis isolates, encountered in foods, have been attributed to the occurrence of the spoVA2mob operon carried on the Tn1546 transposon. In this study, we further investigate the correlation between the presence of this operon in high-level-heat-resistant spores and their germination efficiencies before and after exposure to various sublethal heat treatments (heat activation, or HA), which are known to significantly improve spore responses to nutrient germinants. We show that high-level-heat-resistant spores harboring spoVA2mob required higher HA temperatures for efficient germination than spores lacking spoVA2mob The optimal spore HA requirements additionally depended on the nutrients used to trigger germination, l-alanine (l-Ala), or a mixture of l-asparagine, d-glucose, d-fructose, and K+ (AGFK). The distinct HA requirements of these two spore germination pathways are likely related to differences in properties of specific germinant receptors. Moreover, spores that germinated inefficiently in AGFK contained specific changes in sequences of the GerB and GerK germinant receptors, which are involved in this germination response. In contrast, no relation was found between transcription levels of main germination genes and spore germination phenotypes. The findings presented in this study have great implications for practices in the food industry, where heat treatments are commonly used to inactivate pathogenic and spoilage microbes, including bacterial spore formers.IMPORTANCE This study describes a strong variation in spore germination capacities and requirements for a heat activation treatment, i.e., an exposure to sublethal heat that increases spore responsiveness to nutrient germination triggers, among 17 strains of B. subtilis, including 9 isolates from spoiled food products. Spores of industrial foodborne isolates exhibited, on average, less efficient and slower germination responses and required more severe heat activation than spores from other sources. High heat activation requirements and inefficient, slow germination correlated with elevated resistance of spores to heat and with specific genetic features, indicating a common genetic basis of these three phenotypic traits. Clearly, interstrain variation and numerous factors that shape spore germination behavior challenge standardization of methods to recover highly heat-resistant spores from the environment and have an impact on the efficacy of preservation techniques used by the food industry to control spores.
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Porębska I, Sokołowska B, Skąpska S, Rzoska SJ. Treatment with high hydrostatic pressure and supercritical carbon dioxide to control Alicyclobacillus acidoterrestris spores in apple juice. Food Control 2017. [DOI: 10.1016/j.foodcont.2016.06.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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‘Omics’ for microbial food stability: Proteomics for the development of predictive models for bacterial spore stress survival and outgrowth. Int J Food Microbiol 2017; 240:11-18. [DOI: 10.1016/j.ijfoodmicro.2016.05.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 05/03/2016] [Accepted: 05/06/2016] [Indexed: 12/25/2022]
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Use of Raman Spectroscopy and Phase-Contrast Microscopy To Characterize Cold Atmospheric Plasma Inactivation of Individual Bacterial Spores. Appl Environ Microbiol 2016; 82:5775-84. [PMID: 27422840 DOI: 10.1128/aem.01669-16] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Accepted: 07/13/2016] [Indexed: 12/22/2022] Open
Abstract
UNLABELLED Raman spectroscopy and phase-contrast microscopy were used to examine calcium dipicolinate (CaDPA) levels and rates of nutrient and nonnutrient germination of multiple individual Bacillus subtilis spores treated with cold atmospheric plasma (CAP). Major results for this work include the following: (i) >5 logs of spores deposited on glass surfaces were inactivated by CAP treatment for 3 min, while deposited spores placed inside an impermeable plastic bag were inactivated only ∼2 logs in 30 min; (ii) >80% of the spores treated for 1 to 3 min with CAP were nonculturable and retained CaDPA in their core, while >95% of spores treated with CAP for 5 to 10 min lost all CaDPA; (iii) Raman measurements of individual CAP-treated spores without CaDPA showed differences from spores that germinated with l-valine in terms of nucleic acids, lipids, and proteins; and (iv) 1 to 2 min of CAP treatment killed 99% of spores, but these spores still germinated with nutrients or exogenous CaDPA, albeit more slowly and to a lesser extent than untreated spores, while spores CAP treated for >3 min that retained CaDPA did not germinate via nutrients or CaDPA. However, even after 1 to 3 min of CAP treatment, spores germinated normally with dodecylamine. These results suggest that exposure to the present CAP configuration severely damages a spore's inner membrane and key germination proteins, such that the treated spores either lose CaDPA or can neither initiate nor complete germination with nutrients or CaDPA. Analysis of the various CAP components indicated that UV photons contributed minimally to spore inactivation, while charged particles and reactive oxygen species contributed significantly. IMPORTANCE Much research has shown that cold atmospheric plasma (CAP) is a promising tool for the inactivation of spores in the medical and food industries. However, knowledge about the effects of plasma treatment on spore properties is limited, especially at the single-cell level. In this study, Raman spectroscopy and phase-contrast microscopy were used to analyze CaDPA levels and kinetics of nutrient- and non-nutrient-germinant-induced germination of multiple individual spores of Bacillus subtilis that were treated by a planar CAP device. The roles of different plasma species involved in spore inactivation were also investigated. The knowledge obtained in this study will aid in understanding the mechanism(s) of spore inactivation by CAP and potentially facilitate the development of more effective and efficient plasma sterilization techniques in various applications.
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