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Sundaresan A, Cheong I. Elucidating Bacterial Spore Dynamics through Lanthanide-Enhanced Live Imaging. ACS Sens 2024; 9:789-798. [PMID: 38221734 DOI: 10.1021/acssensors.3c02083] [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] [Indexed: 01/16/2024]
Abstract
Identifying and distinguishing dormant and active bacterial spores are vital for biosecurity, food safety, and space exploration. Yet, there is a lack of simple, quick, and nondestructive methods to achieve this. The common Schaeffer-Fulton method is both sample-destructive and requires significant operator involvement. In this study, we employed lanthanide-beta-diketonate complexes to directly observe both dormant and germinated single spores. Staining is instantaneous and requires minimal sample processing. The complex stains areas outside the core of dormant spores, leaving the core hollow and nonfluorescent. However, upon germination, the complex enters the core, making it brightly fluorescent. This difference was noted in five bacterial species including Bacillus, Clostridium, and Clostridioides. Various lanthanides and beta-diketonates can be mixed to form a range of spore-visualizing complexes. Due to their low toxicity, these complexes allow for live imaging of single germinating spores. We demonstrate low-cost imaging using a USB microscope as well as imaging of spores in milk matrices. This method provides a valuable tool for studying bacterial spores.
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Affiliation(s)
- Ajitha Sundaresan
- Temasek Life Sciences Laboratory, National University of Singapore, 117604 Singapore
- Department of Biological Sciences, National University of Singapore, 117558 Singapore
| | - Ian Cheong
- Temasek Life Sciences Laboratory, National University of Singapore, 117604 Singapore
- Department of Biological Sciences, National University of Singapore, 117558 Singapore
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Cetinkaya YN, Bulut O, Oktem HA, Yilmaz MD. Fluorescent silica nanoparticles as nano-chemosensors for the sequential detection of Pb 2+ ions and bacterial-spore biomarker dipicolinic acid (DPA) in aqueous solution. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2023; 303:123222. [PMID: 37542871 DOI: 10.1016/j.saa.2023.123222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 07/07/2023] [Accepted: 07/30/2023] [Indexed: 08/07/2023]
Abstract
Herein, we report fluorescein-labelled silica nanoparticles (FSNP) which serve as fluorescent nano-chemosensors for sequential detection of Pb2+ (which is a toxic heavy metal) and dipicolinic acid (DPA) (which is a distinctive indicator biomarker of bacterial spores) with high sensitivity and selectivity. The fluorescence of FSNP is quenched because of the complex formation between Pb2+ ions and surface amide groups, however, the fluorescence is recovered in contact with DPA, resulting from the association of DPA with surface bound Pb2+ ions. FSNP-Pb2+ complexes show high sensitivity towards DPA with a low detection limit of 850 nM which is approximately seventy times lower than the infectious dosage of bacterial spores (60 μM). Lateral flow test platform was further developed to show the applicability and practicability of our system.
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Affiliation(s)
- Yagmur Nur Cetinkaya
- Department of Materials Science and Nanotechnology, Graduate School of Natural and Applied Sciences, Konya Food and Agriculture University, 42080 Konya, Turkey
| | - Onur Bulut
- Department of Bioengineering, Faculty of Engineering and Architecture, Konya Food and Agriculture University, 42080 Konya, Turkey
| | - Huseyin Avni Oktem
- Department of Biological Sciences, Middle East Technical University, 06800 Ankara, Turkey; Nanobiz Technology Inc., Gallium Block No: 27 / 218, METU Technopolis, Ankara, Turkey
| | - M Deniz Yilmaz
- Department of Basic Sciences, Faculty of Engineering, Necmettin Erbakan University, 42140 Konya, Turkey; BITAM-Science and Technology Research and Application Center, Necmettin Erbakan University, 42140 Konya, Turkey.
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Wahia H, Fakayode OA, Mintah BK, Mustapha AT, Zhou C, Dabbour M. Effect of dual-frequency thermosonication, food matrix, and germinants on Alicyclobacillus acidoterrestris spore germination. Food Res Int 2023; 171:113054. [PMID: 37330854 DOI: 10.1016/j.foodres.2023.113054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Revised: 05/23/2023] [Accepted: 05/24/2023] [Indexed: 06/19/2023]
Abstract
The off-odors associated with spoilage of acidic beverages are linked to the germination and growth of Alicyclobacillus acidoterrestris (AAT) spores. As a consequence, we determined the influence of nutrients, non-nutrient germinants, dual-frequency thermosonication (DFTS), and food matrix on spore germination. AAT spores in orange juice (OJ), supplemented by L-alanine (L-ala), had the highest germination rate and lowest DPA content at 10 h of incubation. The formation of microscopic pores in cell membranes during DFTS caused irreversible damage in AAT spores in citrate buffer solution (CBS); however, it stimulated AAT spore germination in CBS containing L-ala. Hence, the germination potential was established in the order: L-ala > Calcium dipicolinate > asparagine, glucose, fructose, and potassium ion mixture (AGFK) > L-valine. The conductivity analysis indicated that membrane damage could be a key factor contributing to the artificial germination in CBS. AFM images revealed that after 2 h of adding L-ala, the protein content increased with increased germinated cells. TEM showed that membrane poration and coat detachment were the main pre-germination morphological changes detected after DFTS treatment. This study provides evidence that germination stimulated with DFTS might be an effective strategy for reducing A. acidoterrestris spores in fruit juices.
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Affiliation(s)
- Hafida Wahia
- School of Food and Biological Engineering, Jiangsu University, Zhenjiang 212013, PR China
| | | | | | | | - Cunshan Zhou
- School of Food and Biological Engineering, Jiangsu University, Zhenjiang 212013, PR China; School of Biological and Food Engineering, Chuzhou University, Chuzhou, 239000, PR China.
| | - Mokhtar Dabbour
- Department of Agricultural and Biosystems Engineering, Faculty of Agriculture, Benha University, PO Box 13736, Moshtohor, Qaluobia, Egypt
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Wahia H, Fakayode OA, Mustapha AT, Zhou C, Dabbour M. Application and potential of multifrequency ultrasound in juice industry: Comprehensive analysis of inactivation and germination of Alicyclobacillus acidoterrestris spores. Crit Rev Food Sci Nutr 2022; 64:4561-4586. [PMID: 36412233 DOI: 10.1080/10408398.2022.2143475] [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] [Indexed: 11/23/2022]
Abstract
The majority of acidic fruits are perishable owing to their high-water activity, which promotes microbial activity, thus exhibiting metabolic functions that cause spoilage. Along with sanitary practices, several treatments are used during processing and/or storage to inhibit the development of undesirable bacteria. To overcome the challenges caused by mild heat treatment, juice manufacturers have recently increased their involvement in developing novel non-thermal processing procedures. Ultrasonication alone or in combination with other hurdle technologies may be used to pasteurize processed fruit juices. Multifrequency ultrasound has gained popularity due to the fact that mono-frequency ultrasound has less impact on bacterial inactivation and bioactive compound enhancement of fruit juice. Here, we present and discuss the fundamental information and technological knowledge of how spoilage bacteria, specifically Alicyclobacillus acidoterrestris, assemble resistant spores and inactivate and germinate dormant spores in response to nutrient germinants and physical treatments such as heat and ultrasound. To the authors' knowledge, no prior review of ultrasonic inactivation and germination of A. acidoterrestris in fruit juice exists. Therefore, this article aims to provide a review of previously published research on the inactivation and germination of A. acidoterrestris in fruit juice by ultrasound and heat.
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Affiliation(s)
- Hafida Wahia
- School of Food and Biological Engineering, Jiangsu University, Zhenjiang, PR China
| | | | | | - Cunshan Zhou
- School of Food and Biological Engineering, Jiangsu University, Zhenjiang, PR China
- School of Biological and Food Engineering, Chuzhou University, Chuzhou, PR China
| | - Mokhtar Dabbour
- Department of Agricultural and Biosystems Engineering, Faculty of Agriculture, Benha University, Moshtohor, Qaluobia, Egypt
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Heat activation and inactivation of bacterial spores. Is there an overlap? Appl Environ Microbiol 2022; 88:e0232421. [PMID: 35020450 DOI: 10.1128/aem.02324-21] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Heat activation at a sublethal temperature is widely applied to promote Bacillus species spore germination. This treatment also has potential to be employed in food processing to eliminate undesired bacterial spores by enhancing their germination, and then inactivating the less heat resistant germinated spores at a milder temperature. However, incorrect heat treatment could also generate heat damage in spores, and lead to more heterogeneous spore germination. Here, the heat activation and heat damage profile of Bacillus subtilis spores was determined by testing spore germination and outgrowth at both population and single spore levels. The heat treatments used were 40-80°C, and for 0-300 min. The results were as follows. 1) Heat activation at 40-70°C promoted L-valine and L-asparagine-glucose-fructose-potassium (AGFK) induced germination in a time dependent manner. 2) The optimal heat activation temperatures for AGFK and L-valine germination via the GerB plus GerK or GerA germinant receptors were 65 and 50-65°C, respectively. 3) Heat inactivation of dormant spores appeared at 70°C, and the heat damage of molecules essential for germination and growth began at 70 and 65°C, respectively. 4) Heat treatment at 75°C resulted in both activation of germination and damage to the germination apparatus, and 80°C treatment caused more pronounced heat damage. 5) For the spores that should withstand adverse environmental temperatures in nature, heat activation seems functional for a subsequent optimal germination process, while heat damage affected both germination and outgrowth. Importance Bacterial spores are thermal resistant structures that can thus survive preservation strategies and revive through the process of spore germination. The more heat resistant spores are the more heterogeneous they germinate upon adding germinants. Upon germination spores can cause food spoilage and cause food intoxication. Here we provide new information on both heat activation and inactivation regimes and their effects on the (heterogeneity of) spore germination.
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Moderate high-pressure superdormancy in Bacillus spores: properties of superdormant spores and proteins potentially influencing moderate high-pressure germination. Appl Environ Microbiol 2021; 88:e0240621. [PMID: 34910565 PMCID: PMC8863042 DOI: 10.1128/aem.02406-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Resistant bacterial spores are a major concern in industrial decontamination processes. An approach known as pressure-mediated germination-inactivation strategy aims to artificially germinate spores by isostatic pressure to mitigate their resistance to inactivation processes. The successful implementation of such a germination-inactivation strategy relies on the germination of all spores. However, germination is heterogeneous, with some “superdormant” spores germinating extremely slowly or not at all. The present study investigated potential underlying reasons for moderate high-pressure (150 MPa; 37°C) superdormancy of Bacillus subtilis spores. The water and dipicolinic acid content of superdormant spores was compared with that of the initial dormant spore population. The results suggest that water and dipicolinic acid content are not major drivers of moderate high-pressure superdormancy. A proteomic analysis was used to identify proteins that were quantified at significantly different levels in superdormant spores. Subsequent validation of the germination capacity of deletion mutants revealed that the presence of protein YhcN is required for efficient moderate high-pressure germination and that proteins MinC, cse60, and SspK may also play a role, albeit a minor one. IMPORTANCE Spore-forming bacteria are ubiquitous in nature and, as a consequence, inevitably enter the food chain or other processing environments. Their presence can lead to significant spoilage or safety-related issues. Intensive treatment is usually required to inactivate them; however, this treatment harms important product quality attributes. A pressure-mediated germination-inactivation approach can balance the need for effective spore inactivation and retention of sensitive ingredients. However, superdormant spores are the bottleneck preventing the successful and safe implementation of such a strategy. An in-depth understanding of moderate high-pressure germination and the underlying causes of superdormancy is necessary to advance the development of mild high pressure-based spore control technologies. The approach used in this work allowed the identification of proteins that have not yet been associated with reduced germination at moderate high pressure. This research paves the way for further studies on the germination and superdormancy mechanisms in spores, assisting the development of mild spore inactivation strategies.
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Ryu Y, Hong M, Kim SB, Lee TK, Park W. Raman spectroscopy reveals alteration of spore compositions under different nutritional conditions in Lysinibacillus boronitolerans YS11. J Microbiol 2021; 59:491-499. [PMID: 33779962 DOI: 10.1007/s12275-021-0679-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 01/28/2021] [Accepted: 02/08/2021] [Indexed: 01/01/2023]
Abstract
Little is known about final spores components when bacteria undergo sporulation under different nutrient conditions. Different degrees of resistance and germination rates were observed in the three types of spores of Lysinibacillus boronitolerans YS11 (SD, Spores formed in Difco sporulation medium™; SC and SF, Spores formed in an agricultural byproduct medium with 10 mM CaCl2 and with 10 mM FeSO4, respectively). Stronger UV resistance was recorded for SF with 1.8-2.3-fold greater survival than SC and SD under UV treatment. The three spore types showed similar heat resistances at 80°C, but survival rates of SC and SD were much higher (∼1,000 times) than those of SF at 90°C. However, germination capacity of SF was 20% higher than those of SD and SC on Luria-Bertani agar plates for 24 h. SF germinated more rapidly in a liquid medium with high NaCl concentrations than SC and SD, but became slower under alkaline conditions. Raman spectroscopy was used to analyze the heterogeneities in the three types of vegetative cells and their spores under different nutritional conditions. Exponentially grown-each vegetative cells had different overall Raman peak values. Raman peaks of SC, SD, and SF also showed differences in adenine and amide III compositions and nucleic acid contents. Our data along with Raman spectroscopy provided the evidence that spores formed under under different growth conditions possess very different cellular components, which affected their survival and germination rates.
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Affiliation(s)
- Youngung Ryu
- Laboratory of Molecular Environmental Microbiology, Department of Environmental Science and Ecological Engineering, Korea University, Seoul, 02841, Republic of Korea
| | - Minyoung Hong
- Laboratory of Molecular Environmental Microbiology, Department of Environmental Science and Ecological Engineering, Korea University, Seoul, 02841, Republic of Korea
| | - Soo Bin Kim
- Department of Environmental Engineering, Yonsei University, Wonju, 26493, Republic of Korea
| | - Tae Kwon Lee
- Department of Environmental Engineering, Yonsei University, Wonju, 26493, Republic of Korea
| | - Woojun Park
- Laboratory of Molecular Environmental Microbiology, Department of Environmental Science and Ecological Engineering, Korea University, Seoul, 02841, Republic of Korea.
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Predicting the Structure and Dynamics of Membrane Protein GerAB from Bacillus subtilis. Int J Mol Sci 2021; 22:ijms22073793. [PMID: 33917581 PMCID: PMC8038838 DOI: 10.3390/ijms22073793] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Revised: 03/30/2021] [Accepted: 04/01/2021] [Indexed: 12/12/2022] Open
Abstract
Bacillus subtilis forms dormant spores upon nutrient depletion. Germinant receptors (GRs) in spore’s inner membrane respond to ligands such as L-alanine, and trigger spore germination. In B. subtilis spores, GerA is the major GR, and has three subunits, GerAA, GerAB, and GerAC. L-Alanine activation of GerA requires all three subunits, but which binds L-alanine is unknown. To date, how GRs trigger germination is unknown, in particular due to lack of detailed structural information about B subunits. Using homology modelling with molecular dynamics (MD) simulations, we present structural predictions for the integral membrane protein GerAB. These predictions indicate that GerAB is an α-helical transmembrane protein containing a water channel. The MD simulations with free L-alanine show that alanine binds transiently to specific sites on GerAB. These results provide a starting point for unraveling the mechanism of L-alanine mediated signaling by GerAB, which may facilitate early events in spore germination.
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Podrzaj L, Burtscher J, Küller F, Domig KJ. Strain-Dependent Cheese Spoilage Potential of Clostridium tyrobutyricum. Microorganisms 2020; 8:microorganisms8111836. [PMID: 33266400 PMCID: PMC7700369 DOI: 10.3390/microorganisms8111836] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 11/18/2020] [Accepted: 11/19/2020] [Indexed: 11/23/2022] Open
Abstract
Clostridium tyrobutyricum, a Gram-positive, anaerobic, spore-forming bacterium, is considered as one of the main causative agents for spoilage of hard and semihard cheeses. Growth of C. tyrobutyricum in cheese is critically influenced by ripening temperature and time, pH, salt and lactic acid concentration, moisture and fat content, and the presence of other microorganisms. Previous studies revealed high intraspecies diversity of C. tyrobutyricum strains and variable tolerance toward pH, temperatures, and salt concentrations. These findings indicate that strain-dependent characteristics may be relevant to assess the risk for cheese spoilage if clostridial contamination occurs. In this study, we aimed to compare the phenotypes of 12 C. tyrobutyricum strains which were selected from 157 strains on the basis of genotypic and proteotypic variability. The phenotypic analysis comprised the assessment of gas production and organic acid concentrations in an experimental cheese broth incubated at different temperatures (37, 20, and 14 °C). For all tested strains, delayed gas production at lower incubation temperatures and a strong correlation between gas production and the change in organic acid concentrations were observed. However, considering the time until gas production was visible at different incubation temperatures, a high degree of heterogeneity was found among the tested strains. In addition, variation among replicates of the same strain and differences due to different inoculum levels became evident. This study shows, that, among other factors, strain-specific germination and growth characteristics should be considered to evaluate the risk of cheese spoilage by C. tyrobutyricum.
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Affiliation(s)
- Lucija Podrzaj
- Institute of Food Science, University of Natural Resources and Life Sciences Vienna (BOKU), 1190 Vienna, Austria; (L.P.); (F.K.); (K.J.D.)
- Austrian Competence Centre for Feed and Food Quality, Safety and Innovation (FFoQSI GmbH), Technopark 1C, 3430 Tulln, Austria
| | - Johanna Burtscher
- Institute of Food Science, University of Natural Resources and Life Sciences Vienna (BOKU), 1190 Vienna, Austria; (L.P.); (F.K.); (K.J.D.)
- Correspondence: ; Tel.: +43-1-47654-75456
| | - Franziska Küller
- Institute of Food Science, University of Natural Resources and Life Sciences Vienna (BOKU), 1190 Vienna, Austria; (L.P.); (F.K.); (K.J.D.)
- Austrian Competence Centre for Feed and Food Quality, Safety and Innovation (FFoQSI GmbH), Technopark 1C, 3430 Tulln, Austria
| | - Konrad J. Domig
- Institute of Food Science, University of Natural Resources and Life Sciences Vienna (BOKU), 1190 Vienna, Austria; (L.P.); (F.K.); (K.J.D.)
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Rao L, Wang Y, Chen F, Hu X, Liao X, Zhao L. High pressure CO2 reduces the wet heat resistance of Bacillus subtilis spores by perturbing the inner membrane. INNOV FOOD SCI EMERG 2020. [DOI: 10.1016/j.ifset.2020.102291] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Ghosh S, Joseph G, Korza G, He L, Yuan J, Dong W, Setlow B, Li Y, Savage P, Setlow P. Effects of the microbicide ceragenin CSA‐13 on and properties ofBacillus subtilisspores prepared on two very different media. J Appl Microbiol 2019; 127:109-120. [DOI: 10.1111/jam.14300] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 03/23/2019] [Accepted: 04/30/2019] [Indexed: 12/25/2022]
Affiliation(s)
- S. Ghosh
- Department of Molecular Biology and Biophysics UConn Health Farmington CT USA
- Department of Science and Mathematics Capital Community College Hartford CT USA
| | - G. Joseph
- Department of Molecular Biology and Biophysics UConn Health Farmington CT USA
| | - G. Korza
- Department of Molecular Biology and Biophysics UConn Health Farmington CT USA
| | - L. He
- Department of Physics East Carolina University Greenville NC USA
- School of Electronic Engineering Dongguan University of Technology Dongguan People’s Republic of China
| | - J.‐H. Yuan
- Department of Physics East Carolina University Greenville NC USA
| | - W. Dong
- Department of Molecular Biology and Biophysics UConn Health Farmington CT USA
- School of Resource and Environmental Engineering Jiangxi University of Science and Technology Ganzhou China
| | - B. Setlow
- Department of Molecular Biology and Biophysics UConn Health Farmington CT USA
| | - Y.‐Q. Li
- Department of Physics East Carolina University Greenville NC USA
- School of Electronic Engineering Dongguan University of Technology Dongguan People’s Republic of China
| | - P.B. Savage
- Department of Chemistry and Biochemistry Brigham Young University Provo UT USA
| | - P. Setlow
- Department of Molecular Biology and Biophysics UConn Health Farmington CT USA
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Zhang Y, Mathys A. Superdormant Spores as a Hurdle for Gentle Germination-Inactivation Based Spore Control Strategies. Front Microbiol 2019; 9:3163. [PMID: 30662433 PMCID: PMC6328458 DOI: 10.3389/fmicb.2018.03163] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Accepted: 12/06/2018] [Indexed: 02/04/2023] Open
Abstract
Bacterial spore control strategies based on the germination-inactivation principle can lower the thermal load needed to inactivate bacterial spores and thus preserve food quality better. However, the success of this strategy highly depends on the germination of spores, and a subpopulation of spores that fail to germinate or germinate extremely slowly hinders the application of this strategy. This subpopulation of spores is termed 'superdormant (SD) spores.' Depending on the source of the germination stimulus, SD spores are categorized as nutrient-SD spores, Ca2+-dipicolinic acid SD spores, dodecylamine-SD spores, and high pressure SD spores. In recent decades, research has been done to isolate these different groups of SD spores and unravel the cause of their germination deficiency as well as their germination capacities. This review summarizes the challenges caused by SD spores, their isolation and characterization, the underlying mechanisms of their germination deficiency, and the future research directions needed to tackle this topic in further depth.
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Affiliation(s)
| | - Alexander Mathys
- Sustainable Food Processing Laboratory, Institute of Food, Nutrition and Health, Department of Health Science and Technology, ETH Zurich, Zurich, Switzerland
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Dong W, Setlow P. Fluoride movement into and out of Bacillus spores and growing cells and effects of fluoride accumulation on spore properties. J Appl Microbiol 2018; 126:503-515. [PMID: 30430725 DOI: 10.1111/jam.14155] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 11/04/2018] [Accepted: 11/05/2018] [Indexed: 12/25/2022]
Abstract
AIMS To investigate effects of fluoride ion (F- ) on, and kinetics of its movement into and out of, spores and growing cells of Bacillus species. METHODS AND RESULTS Effects of F- on Bacillus cell growth, spore germination and outgrowth and heat resistance were investigated, as well as F- movement into and out of spores using 19 F-NMR. F- inhibited Bacillus subtilis spore germination and outgrowth, and YhdU, now named FluC, was crucial to prevent F- accumulation in growing cells and to minimize F- inhibition of spore germination. Dormant wild-type, yhdU and coat defective B. subtilis spores, and Bacillus cereus spores incubated in 40 mmol l-1 NaF for 48 h accumulated 2-2·6 mol l-1 F- and its movement into Bacillus spores was highest at low pH. Bacillus subtilis spores lacking Ca-dipicolinic acid accumulated higher F- levels than wild-type spores. CONCLUSIONS These results are consistent with F- incorporation into the dormant spore core, and as HF and/or NaF, but not CaF2 . YhdU played no significant role in F- uptake or efflux in dormant spores, but assisted in F- export early in spore germination. SIGNIFICANCE AND IMPACT OF STUDY This knowledge provides new insight into effects of F- on Bacillus cells and spores and how this anion moves into, and out of spores.
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Affiliation(s)
- W Dong
- School of Resource and Environmental Engineering, Jiangxi University of Science and Technology, Ganzhou, China.,Department of Molecular Biology and Biophysics, UConn Health, Farmington, CT, USA
| | - P Setlow
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, CT, USA
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14
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Microbiota of milk powders and the heat resistance and spoilage potential of aerobic spore-forming bacteria. Int Dairy J 2018. [DOI: 10.1016/j.idairyj.2018.06.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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15
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16
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Rao L, Feeherry FE, Ghosh S, Liao X, Lin X, Zhang P, Li Y, Doona CJ, Setlow P. Effects of lowering water activity by various humectants on germination of spores of Bacillus species with different germinants. Food Microbiol 2018; 72:112-127. [DOI: 10.1016/j.fm.2017.11.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 11/19/2017] [Accepted: 11/23/2017] [Indexed: 10/18/2022]
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17
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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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Walking dead: Permeabilization of heat-treated Geobacillus stearothermophilus ATCC 12980 spores under growth-preventing conditions. Food Microbiol 2017; 64:126-134. [DOI: 10.1016/j.fm.2016.12.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Revised: 12/19/2016] [Accepted: 12/19/2016] [Indexed: 11/20/2022]
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20
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Kostrzewska-Szlakowska I, Kiersztyn B. Microbial Biomass and Enzymatic Activity of the Surface Microlayer and Subsurface Water in Two Dystrophic Lakes. Pol J Microbiol 2017; 66:75-84. [PMID: 29359687 DOI: 10.5604/17331331.1234995] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Nutrient and organic matter concentration, microbial biomass and activities were studied at the surface microlayers (SML) and subsurface waters (SSW) in two small forest lakes of different water colour. The SML in polyhumic lake is more enriched with dissolved inorganic nitrogen (0.141 mg l-1) than that of oligohumic lake (0.124 mg l-1), the former also contains higher levels of total nitrogen (2.66 mg l-1). Higher activities of lipase (Vmax 2290 nmol l-1 h-1 in oligo- and 6098 in polyhumic) and glucosidase (Vmax 41 nmol l-1 h-1 in oligo- and 49 in polyhumic) were in the SMLs in both lakes. Phosphatase activity was higher in the oligohumic SML than in SSW (Vmax 632 vs. 339 nmol l-1 h-1) while in polyhumic lake was higher in SSW (Vmax 2258 nmol l-1 h-1 vs. 1908 nmol l-1 h-1). Aminopeptidase activity in the SSW in both lakes was higher than in SMLs (Vmax 2117 in oligo- and 1213 nmol l-1 h-1 in polyhumic). It seems that solar radiation does inhibit neuston microbial community as a whole because secondary production and the share of active bacteria in total bacteria number were higher in SSW. However, in the oligohumic lake the abundance of bacteria in the SML was always higher than in the SSW (4.07 vs. 2.69 × 106 cells ml-1) while in the polyhumic lake was roughly equal (4.48 vs. 4.33 × 106 cells ml-1) in both layers. Results may also suggest that surface communities are not supplemented by immigration from bulk communities. The SML of humic lakes may act as important sinks for allochthonous nutrient resources and may then generate considerable energy pools for microbial food webs.
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Affiliation(s)
| | - Bartosz Kiersztyn
- Department of Microbial Ecology and Environmental Biotechnology, Institute of Botany, University of Warsaw; Biological and Chemical Research Centre, Warszawa, Poland
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Johnson CL, Moir A. Proteins YlaJ and YhcN contribute to the efficiency of spore germination in Bacillus subtilis. FEMS Microbiol Lett 2017; 364:3045907. [DOI: 10.1093/femsle/fnx047] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Accepted: 02/22/2017] [Indexed: 11/14/2022] Open
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Draft Genome Sequences of 10 Bacillus subtilis Strains That Form Spores with High or Low Heat Resistance. GENOME ANNOUNCEMENTS 2016; 4:4/2/e00124-16. [PMID: 26988043 PMCID: PMC4796122 DOI: 10.1128/genomea.00124-16] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Here, we report the draft genome sequences of 10 isolates of Bacillus subtilis, a spore forming Gram-positive bacterium. The strains were selected from food products and produced spores with either high or low heat resistance.
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23
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Abstract
Bacterial spores, despite being metabolically dormant, possess the remarkable capacity to detect nutrients and other molecules in their environment through a biochemical sensory apparatus that can trigger spore germination, allowing the return to vegetative growth within minutes of exposure of germinants. We demonstrate here that bacterial spores of multiple species retain memory of transient exposures to germinant stimuli that can result in altered responses to subsequent exposure. The magnitude and decay of these memory effects depend on the pulse duration as well as on the separation time, incubation temperature, and pH values between the pulses. Spores of Bacillus species germinate in response to nutrients that interact with germinant receptors (GRs) in the spore’s inner membrane, with different nutrient types acting on different receptors. In our experiments, B. subtilis spores display memory when the first and second germinant pulses target different receptors, suggesting that some components of spore memory are downstream of GRs. Furthermore, nonnutrient germinants, which do not require GRs, exhibit memory either alone or in combination with nutrient germinants, and memory of nonnutrient stimulation is found to be more persistent than that induced by GR-dependent stimuli. Spores of B. cereus and Clostridium difficile also exhibit germination memory, suggesting that memory may be a general property of bacterial spores. These observations along with experiments involving strains with mutations in various germination proteins suggest a model in which memory is stored primarily in the metastable states of SpoVA proteins, which comprise a channel for release of dipicolinic acid, a major early event in spore germination. Cellular memory is defined as a sustained response to a transient environmental stimulus, and yet its generation and storage have not been described in bacterial spores. We demonstrate here that bacterial spores of multiple species retain memory of transient exposures to germinant stimuli that can result in altered responses to subsequent exposure. Memory was induced by activation of germinant receptors (GRs) or by GR-independent germinants and was accessed by both GR-dependent and GR-independent germinants. Analysis of effects on memory of exposure to GR-dependent and GR-independent germinants as well as in spores lacking various germination proteins suggests a model in which memory is stored primarily in metastable states of SpoVA proteins which comprise a channel for release of spore dipicolinic acid. Spore memory can also significantly reduce the concentration of nutrient germinants necessary to trigger germination, and this may be used to respond to low levels of nutrient germinants.
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Characterization of the Dynamic Germination of Individual Clostridium difficile Spores Using Raman Spectroscopy and Differential Interference Contrast Microscopy. J Bacteriol 2015; 197:2361-73. [PMID: 25939833 DOI: 10.1128/jb.00200-15] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2015] [Accepted: 04/27/2015] [Indexed: 12/18/2022] Open
Abstract
UNLABELLED The Gram-positive spore-forming anaerobe Clostridium difficile is a leading cause of nosocomial diarrhea. Spores of C. difficile initiate infection when triggered to germinate by bile salts in the gastrointestinal tract. We analyzed germination kinetics of individual C. difficile spores using Raman spectroscopy and differential interference contrast (DIC) microscopy. Similar to Bacillus spores, individual C. difficile spores germinating with taurocholate plus glycine began slow leakage of a ∼15% concentration of a chelate of Ca(2+) and dipicolinic acid (CaDPA) at a heterogeneous time T1, rapidly released CaDPA at Tlag, completed CaDPA release at Trelease, and finished peptidoglycan cortex hydrolysis at Tlysis. T1 and Tlag values for individual spores were heterogeneous, but ΔTrelease periods (Trelease - Tlag) were relatively constant. In contrast to Bacillus spores, heat treatment did not stimulate spore germination in the two C. difficile strains tested. C. difficile spores did not germinate with taurocholate or glycine alone, and different bile salts differentially promoted spore germination, with taurocholate and taurodeoxycholate being best. Transient exposure of spores to taurocholate plus glycine was sufficient to commit individual spores to germinate. C. difficile spores did not germinate with CaDPA, in contrast to B. subtilis and C. perfringens spores. However, the detergent dodecylamine induced C. difficile spore germination, and rates were increased by spore coat removal although cortex hydrolysis did not follow Trelease, in contrast with B. subtilis. C. difficile spores lacking the cortex-lytic enzyme, SleC, germinated extremely poorly, and cortex hydrolysis was not observed in the few sleC spores that partially germinated. Overall, these findings indicate that C. difficile and B. subtilis spore germination exhibit key differences. IMPORTANCE Spores of the Gram-positive anaerobe Clostridium difficile are responsible for initiating infection by this important nosocomial pathogen. When exposed to germinants such as bile salts, C. difficile spores return to life through germination in the gastrointestinal tract and cause disease, but their germination has been studied only with population-wide measurements. In this work we used Raman spectroscopy and DIC microscopy to monitor the kinetics of germination of individual C. difficile spores, the commitment of spores to germination, and the effect of germinant type and concentration, sublethal heat shock, and spore decoating on germination. Our data suggest that the order of germination events in C. difficile spores differs from that in Bacillus spores and provide new insights into C. difficile spore germination.
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Slow leakage of Ca-dipicolinic acid from individual bacillus spores during initiation of spore germination. J Bacteriol 2015; 197:1095-103. [PMID: 25583976 DOI: 10.1128/jb.02490-14] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
When exposed to nutrient or nonnutrient germinants, individual Bacillus spores can return to life through germination followed by outgrowth. Laser tweezers, Raman spectroscopy, and either differential interference contrast or phase-contrast microscopy were used to analyze the slow dipicolinic acid (DPA) leakage (normally ∼20% of spore DPA) from individual spores that takes place prior to the lag time, Tlag, when spores begin rapid release of remaining DPA. Major conclusions from this work with Bacillus subtilis spores were as follows: (i) slow DPA leakage from wild-type spores germinating with nutrients did not begin immediately after nutrient exposure but only at a later heterogeneous time T1; (ii) the period of slow DPA leakage (ΔTleakage = Tlag - T1) was heterogeneous among individual spores, although the amount of DPA released in this period was relatively constant; (iii) increases in germination temperature significantly decreased T1 times but increased values of ΔTleakage; (iv) upon germination with l-valine for 10 min followed by addition of d-alanine to block further germination, all germinated spores had T1 times of less than 10 min, suggesting that T1 is the time when spores become committed to germinate; (v) elevated levels of SpoVA proteins involved in DPA movement in spore germination decreased T1 and Tlag times but not the amount of DPA released in ΔTleakage; (vi) lack of the cortex-lytic enzyme CwlJ increased DPA leakage during germination due to longer ΔTleakage times in which more DPA was released; and (vii) there was slow DPA leakage early in germination of B. subtilis spores by the nonnutrients CaDPA and dodecylamine and in nutrient germination of Bacillus cereus and Bacillus megaterium spores. Overall, these findings have identified and characterized a new early event in Bacillus spore germination.
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