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Heckler C, Vale MG, Canales HDS, Stradiotto GC, Giordano ALPL, Schreiber AZ, Sant'Ana AS. Spore-forming bacteria in gelatin: Characterization, identification by 16S rRNA and MALDI-TOF mass spectrometry (MS), and presence of heat resistance and virulence genes. Int J Food Microbiol 2024; 422:110813. [PMID: 38970997 DOI: 10.1016/j.ijfoodmicro.2024.110813] [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: 02/05/2024] [Revised: 06/20/2024] [Accepted: 06/27/2024] [Indexed: 07/08/2024]
Abstract
Gelatin, a versatile protein derived from collagen, is widely used in the food, pharmaceutical and medical sectors. However, bacterial contamination by spore-forming bacteria during gelatin processing represents a significant concern for product safety and quality. In this study, an investigation was carried out to explore the heat and chemical resistance, as well as the identification and characterization of spore-forming bacteria isolated from gelatin processing. The methodologies involved chemical resistance tests with drastic pH in microplates and thermal resistance tests in capillary tubes of various isolates obtained at different processing stages. In addition, phenotypic and genotypic analyses were carried out to characterize the most resistant isolates of spore-forming bacteria. The findings of this study revealed the presence of several species, including Bacillus cereus, Bacillus licheniformis, Bacillus sonorensis, Bacillus subtilis, Geobacillus stearothermophilus, and Clostridium sporogenes, with some isolates exhibiting remarkable chemical and heat resistances. In addition, a significant proportion of the most resistant isolates showed gelatinase activity (n = 19/21; 90.5 %) and the presence of heat resistance (n = 5/21; 23.8 %), and virulence genes (n = 11/21; 52.4 %). The results of this study suggest that interventions should be done in quality control practices and that process parameter adjustments and effective contamination reduction strategies should be implemented through gelatin processing.
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Affiliation(s)
- Caroline Heckler
- Department of Food Science and Nutrition, Faculty of Food Engineering, University of Campinas, Campinas, São Paulo, Brazil
| | - Matheus G Vale
- Department of Integrated Systems, Faculty of Mechanical Engineering, University of Campinas, Campinas, São Paulo, Brazil
| | - Héctor D S Canales
- Department of Food Science and Nutrition, Faculty of Food Engineering, University of Campinas, Campinas, São Paulo, Brazil
| | - Graziele C Stradiotto
- Department of Food Science and Nutrition, Faculty of Food Engineering, University of Campinas, Campinas, São Paulo, Brazil
| | - Ana Luisa P L Giordano
- Department of Clinical Pathology, Faculty of Medical Sciences, University of Campinas, Campinas, São Paulo, Brazil
| | - Angelica Z Schreiber
- Department of Clinical Pathology, Faculty of Medical Sciences, University of Campinas, Campinas, São Paulo, Brazil
| | - Anderson S Sant'Ana
- Department of Food Science and Nutrition, Faculty of Food Engineering, University of Campinas, Campinas, São Paulo, Brazil.
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2
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Heydenreich R, Delbrück AI, Peternell C, Trunet C, Mathys A. Characterization of high-pressure-treated Bacillus subtilis spore populations using flow cytometry - Shedding light on spore superdormancy at 550 MPa. Int J Food Microbiol 2024; 422:110812. [PMID: 38970996 DOI: 10.1016/j.ijfoodmicro.2024.110812] [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: 03/10/2024] [Revised: 06/04/2024] [Accepted: 06/23/2024] [Indexed: 07/08/2024]
Abstract
Mild spore inactivation can be challenging in industry because of the remarkable resistance of bacterial spores. High pressure (HP) can trigger spore germination, which reduces the spore's resistance, and thereby allows mild spore inactivation. However, spore germination is heterogenous. Some slowly germinating or non-germinating spores called superdormant spores remain resistant and can survive. Therefore, superdormant spores need to be characterized to understand the causes of their germination deficiency. Bacillus subtilis spores were pressurized for 50 s - 6 min at a very high pressure (vHP) level of 550 MPa and 60 °C in buffer to trigger germination. For a rapid quantification of the remaining ungerminated superdormant spores, flow cytometry (FCM) analysis was validated using single cell sorting and growth analysis. FCM based on propidium iodide (PI) and SYTO16 can be used for 550 MPa-superdormant spores after short vHP treatments of ≤1 min and post-HP incubation at 37 °C or 60 °C. The need for a post-HP incubation is particular for vHP treatments. The incubation was successful to separate FCM signals from superdormant and germinated spores, thus allowing superdormant spore quantification. The SYTO16 and PI fluorescence levels did not necessarily indicate superdormancy or apparent viability. This highlights the general need for FCM validation for different HP treatment conditions. The ∼7 % of ungerminated, i.e., superdormant, spores were isolated after a vHP treatment (550 MPa, 60 °C, 43-52 s). This allowed the characterization of vHP superdormant spores for the first time. The superdormant spores had a similar dipicolinic acid content as spores of the initial dormant population. Descendants of superdormant spores had a normal vHP germination capacity. The causes of vHP superdormancy were thus unlikely linked to the dipicolinic acid content or a permanent genetic change. Isolated superdormant spores germinated better in a second vHP treatment compared to the initial spore population. This has not been observed for other germination stimuli so far. In addition, the germination capacity of the initial spore population was time-dependent. A vHP germination deficiency can therefore be lost over time and seems to be caused by transient factors. Permanent cellular properties played a minor role as causes of superdormancy under chosen HP treatment conditions. The study gained new fundamental insights in vHP superdormancy which are of applied interest. Understanding superdormancy helps to efficiently develop a strategy to avoid superdormant spores and hence to inactivate all spores. The development of a mild HP spore germination-inactivation process aims at better preserving the food quality.
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Affiliation(s)
- Rosa Heydenreich
- Sustainable Food Processing Laboratory, Institute of Food, Nutrition, and Health, Department of Health Science and Technology, ETH Zurich, Zurich, Switzerland
| | - Alessia I Delbrück
- Sustainable Food Processing Laboratory, Institute of Food, Nutrition, and Health, Department of Health Science and Technology, ETH Zurich, Zurich, Switzerland
| | - Christina Peternell
- Sustainable Food Processing Laboratory, Institute of Food, Nutrition, and Health, Department of Health Science and Technology, ETH Zurich, Zurich, Switzerland
| | - Clément Trunet
- Univ Brest, INRAE, Laboratoire Universitaire de Biodiversité et Écologie Microbienne, Quimper, France.
| | - 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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Huang Y, Swarge BN, Roseboom W, Bleeker JD, Brul S, Setlow P, Kramer G. Integrative Metabolomics and Proteomics Allow the Global Intracellular Characterization of Bacillus subtilis Cells and Spores. J Proteome Res 2024; 23:596-608. [PMID: 38190553 PMCID: PMC10845140 DOI: 10.1021/acs.jproteome.3c00386] [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: 06/29/2023] [Revised: 12/01/2023] [Accepted: 12/08/2023] [Indexed: 01/10/2024]
Abstract
Reliable and comprehensive multi-omics analysis is essential for researchers to understand and explore complex biological systems more completely. Bacillus subtilis (B. subtilis) is a model organism for Gram-positive spore-forming bacteria, and in-depth insight into the physiology and molecular basis of spore formation and germination in this organism requires advanced multilayer molecular data sets generated from the same sample. In this study, we evaluated two monophasic methods for polar and nonpolar compound extraction (acetonitrile/methanol/water; isopropanol/water, and 60% ethanol) and two biphasic methods (chloroform/methanol/water, and methyl tert-butyl ether/methanol/water) on coefficients of variation of analytes, identified metabolite composition, and the quality of proteomics profiles. The 60% EtOH protocol proved to be the easiest in sample processing and was more amenable to automation. Collectively, we annotated 505 and 484 metabolites and identified 1665 and 1562 proteins in B. subtilis vegetative cells and spores, respectively. We also show differences between vegetative cells and spores from a multi-omics perspective and demonstrate that an integrative multi-omics analysis can be implemented from one sample using the 60% EtOH protocol. The results obtained by the 60% EtOH protocol provide comprehensive insight into differences in the metabolic and protein makeup of B. subtilis vegetative cells and spores.
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Affiliation(s)
- Yixuan Huang
- Laboratory
for Mass Spectrometry of Biomolecules, Swammerdam Institute for Life
Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
- Molecular
Biology and Microbial Food Safety, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - Bhagyashree N. Swarge
- Laboratory
for Mass Spectrometry of Biomolecules, Swammerdam Institute for Life
Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
- Molecular
Biology and Microbial Food Safety, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - Winfried Roseboom
- Laboratory
for Mass Spectrometry of Biomolecules, Swammerdam Institute for Life
Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - Jurre D. Bleeker
- Laboratory
for Mass Spectrometry of Biomolecules, Swammerdam Institute for Life
Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - Stanley Brul
- Molecular
Biology and Microbial Food Safety, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - Peter Setlow
- Department
of Molecular Biology and Biophysics, UConn
Health, Farmington, Connecticut 06030-3305, United States
| | - Gertjan Kramer
- Laboratory
for Mass Spectrometry of Biomolecules, Swammerdam Institute for Life
Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
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Mortier J, Govers SK, Cambré A, Van Eyken R, Verheul J, den Blaauwen T, Aertsen A. Protein aggregates act as a deterministic disruptor during bacterial cell size homeostasis. Cell Mol Life Sci 2023; 80:360. [PMID: 37971522 PMCID: PMC11072981 DOI: 10.1007/s00018-023-05002-4] [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: 05/02/2023] [Revised: 10/13/2023] [Accepted: 10/15/2023] [Indexed: 11/19/2023]
Abstract
Mechanisms underlying deviant cell size fluctuations among clonal bacterial siblings are generally considered to be cryptic and stochastic in nature. However, by scrutinizing heat-stressed populations of the model bacterium Escherichia coli, we uncovered the existence of a deterministic asymmetry in cell division that is caused by the presence of intracellular protein aggregates (PAs). While these structures typically locate at the cell pole and segregate asymmetrically among daughter cells, we now show that the presence of a polar PA consistently causes a more distal off-center positioning of the FtsZ division septum. The resulting increased length of PA-inheriting siblings persists over multiple generations and could be observed in both E. coli and Bacillus subtilis populations. Closer investigation suggests that a PA can physically perturb the nucleoid structure, which subsequently leads to asymmetric septation.
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Affiliation(s)
- Julien Mortier
- Department of Microbial and Molecular Systems, KU Leuven, Leuven, Belgium
| | - Sander K Govers
- Department of Microbial and Molecular Systems, KU Leuven, Leuven, Belgium
- Department of Biology, KU Leuven, Leuven, Belgium
| | - Alexander Cambré
- Department of Microbial and Molecular Systems, KU Leuven, Leuven, Belgium
| | - Ronald Van Eyken
- Department of Microbial and Molecular Systems, KU Leuven, Leuven, Belgium
| | - Jolanda Verheul
- Swammerdam Institute for Life Sciences, Bacterial Cell Biology and Physiology, University of Amsterdam, Amsterdam, The Netherlands
| | - Tanneke den Blaauwen
- Swammerdam Institute for Life Sciences, Bacterial Cell Biology and Physiology, University of Amsterdam, Amsterdam, The Netherlands
| | - Abram Aertsen
- Department of Microbial and Molecular Systems, KU Leuven, Leuven, Belgium.
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5
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Smita N, Sasikala C, Ramana C. New insights into peroxide toxicology: sporulenes help Bacillus subtilis endospores from hydrogen peroxide. J Appl Microbiol 2023; 134:lxad238. [PMID: 37863832 DOI: 10.1093/jambio/lxad238] [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: 08/17/2023] [Revised: 09/11/2023] [Accepted: 10/19/2023] [Indexed: 10/22/2023]
Abstract
AIM The purpose of the present study was to understand the possible events involved in the toxicity of hydrogen peroxide (H2O2) to wild and sporulene-deficient spores of Bacillus subtilis, as H2O2 was previously shown to have deleterious effects. METHODS AND RESULTS The investigation utilized two strains of B. subtilis, namely the wild-type PY79 (WT) and the sporulene-deficient TB10 (ΔsqhC mutant). Following treatment with 0.05% H2O2 (v/v), spore viability was assessed using a plate count assay, which revealed a significant decrease in cultivability of 80% for the ΔsqhC mutant spores. Possible reasons for the loss of spore viability were investigated with microscopic analysis, dipicholinic acid (DPA) quantification and propidium iodide (PI) staining. Microscopic examinations revealed the presence of withered and deflated morphologies in spores of ΔsqhC mutants treated with H2O2, indicating a compromised membrane permeability. This was further substantiated by the absence of DPA and a high frequency (50%-75%) of PI infiltration. The results of fatty acid methyl ester analysis and protein profiling indicated that the potentiation of H2O2-induced cellular responses was manifested in the form of altered spore composition in ΔsqhC B. subtilis. The slowed growth rates of the ΔsqhC mutant and the heightened sporulene biosynthesis pathways in the WT strain, both upon exposure to H2O2, suggested a protective function for sporulenes in vegetative cells. CONCLUSIONS Sporulenes serve as a protective layer for the inner membrane of spores, thus assuming a significant role in mitigating the adverse effects of H2O2 in WT B. subtilis. The toxic effects of H2O2 were even more pronounced in the spores of the ΔsqhC mutant, which lacks this protective barrier of sporulenes.
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Affiliation(s)
- N Smita
- Department of Plant Sciences, School of Life Sciences, University of Hyderabad, P.O. Central University, Hyderabad 500046, India
| | - Ch Sasikala
- Bacterial Discovery Laboratory, Centre for Environment, Institute of Science and Technology, J.N.T. University Hyderabad, Hyderabad 500085, India
| | - ChV Ramana
- Department of Plant Sciences, School of Life Sciences, University of Hyderabad, P.O. Central University, Hyderabad 500046, India
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Kamoun F, Weekers F, Ayed RB, Mechri S, Jabeur F, Thonart P, Jaouadi B. Multiple linear regression models to simulate spore yields of Bacillus amyloliquefaciens BS13 through optimization of medium composition. Biotechnol Appl Biochem 2022; 69:2686-2697. [PMID: 34994000 DOI: 10.1002/bab.2315] [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: 08/26/2021] [Accepted: 12/28/2021] [Indexed: 12/27/2022]
Abstract
Bacillus amyloliquefaciens is a food spoilage spore-forming bacterium. Its spores are useful for multiple biotechnological applications. Nevertheless, few reports are available regarding the achievement of a high cell density and good sporulation effectiveness under fermentation conditions. Therefore, the current study was designed to optimize a low-cost fermentation medium allowing the highest sporulation yield by B. amyloliquefaciens strain BS13. Our data revealed that tryptone and starch were the best carbon and energy sources. In addition, two nitrogen sources namely, corn steep liquor (CSL) and yeast extract (YE), allowed a significant enhancement of spore production and they were both retained for further optimization. A combination of CaCl2 , MgSO4 , and MnSO4 showed a positive impact on spores' production. The composition of the optimized medium was (in g/L); tryptone 3, starch 15, CSL 13.5, YE 1.5, CaCl2 0.1, MgSO4 ·7H2 O 0.012, and MnSO4 ·7H2 O 0.0012. Such medium was further validated in a 400-L fermentor. The spore yield by B. amyloliquefaciens strain BS13 was enhanced from 3.0 × 1010 spores/mL under flask culture conditions to 6.2 × 1010 spores/mL when cultures were performed on large scale. Therefore, strain BS13 spore preparation could be proposed as a promising probiotic and a biocontrol agent useful for plants, animals, and humans.
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Affiliation(s)
- Fakher Kamoun
- Laboratoire des Biotechnologies Microbiennes et Enzymatiques et Biomolécules, Centre de Biotechnologie de Sfax, Université de Sfax, Sfax, Tunisia
| | | | - Rayda Ben Ayed
- Laboratoire de Procédés de Criblage Moléculaire et Cellulaire, Centre de Biotechnologie de Sfax, Université de Sfax, Sfax, Tunisia
| | - Sondes Mechri
- Laboratoire des Biotechnologies Microbiennes et Enzymatiques et Biomolécules, Centre de Biotechnologie de Sfax, Université de Sfax, Sfax, Tunisia
| | - Fadoua Jabeur
- Laboratoire des Biotechnologies Microbiennes et Enzymatiques et Biomolécules, Centre de Biotechnologie de Sfax, Université de Sfax, Sfax, Tunisia
| | - Philippe Thonart
- Centre Wallon de Biologie Industrielle, Unité de Technologie Microbienne, Université de Liège, Liège, Belgium
| | - Bassem Jaouadi
- Laboratoire des Biotechnologies Microbiennes et Enzymatiques et Biomolécules, Centre de Biotechnologie de Sfax, Université de Sfax, Sfax, Tunisia
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7
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Wang W, Liu Y, Li G, Liu Z, Wong PK, An T. Mechanism insights into bacterial sporulation at natural sphalerite interface with and without light irradiation: The suppressing role in bacterial sporulation by photocatalysis. ENVIRONMENT INTERNATIONAL 2022; 168:107460. [PMID: 35981477 DOI: 10.1016/j.envint.2022.107460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 07/22/2022] [Accepted: 08/07/2022] [Indexed: 06/15/2023]
Abstract
Unveiling the mechanisms of bacterial sporulation at natural mineral interfaces is crucial to fully understand the interactions of mineral with microorganism in aquatic environment. In this study, the bacterial sporulation mechanisms of Bacillus subtilis (B. subtilis) at natural sphalerite (NS) interface with and without light irradiation were systematically investigated for the first time. Under dark condition, NS was found to inactivate vegetative cells of B. subtilis and promote their sporulation simultaneously. The released Zn2+ from NS was mainly responsible for the bacterial inactivation and sporulation. With light irradiation, the photocatalytic effect from NS could increase the bacterial inactivation efficiency, while the bacterial sporulation efficiency was decreased from 8.1 % to 4.5 %. The photo-generated H2O2 and O2- played the major roles in enhancing bacterial inactivation and suppressing bacterial sporulation process. The intracellular synthesis of dipicolinic acid (DPA) as biomarker for sporulation was promoted by NS in dark, which was suppressed by the photocatalytic effect of NS with light irradiation. The transformation process from vegetative cells to spores was monitored by both 3D-fluerecence EEM and SEM observations. Compared with the NS alone system, the NS/light combined system induced higher level of intracellular ROSs, up-regulated antioxidant enzyme activity and decreased cell metabolism activity, which eventually led to enhanced inactivation of vegetative cells and suppressed bacterial sporulation. These results not only provide in-depth understanding about bacterial sporulation as a new mode of sub-lethal stress response at NS interface, but also shed lights on putting forward suitable strategies for controlling spore-producing bacteria by suppressing their sporulation during water disinfection.
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Affiliation(s)
- Wanjun Wang
- Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, Guangdong-Hong Kong-Macao Joint Laboratory for Contaminants Exposure and Health, Institute of Environmental Health and Pollution control, Guangdong University of Technology, Guangzhou 510006, China; Guangzhou Key Laboratory of Environmental Catalysis and Pollution Control, Guangdong Engineering Technology Research Center for Photocatalytic Technology Integration and Equipment, School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, China
| | - Yan Liu
- Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, Guangdong-Hong Kong-Macao Joint Laboratory for Contaminants Exposure and Health, Institute of Environmental Health and Pollution control, Guangdong University of Technology, Guangzhou 510006, China; Guangzhou Key Laboratory of Environmental Catalysis and Pollution Control, Guangdong Engineering Technology Research Center for Photocatalytic Technology Integration and Equipment, School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, China
| | - Guiying Li
- Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, Guangdong-Hong Kong-Macao Joint Laboratory for Contaminants Exposure and Health, Institute of Environmental Health and Pollution control, Guangdong University of Technology, Guangzhou 510006, China; Guangzhou Key Laboratory of Environmental Catalysis and Pollution Control, Guangdong Engineering Technology Research Center for Photocatalytic Technology Integration and Equipment, School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, China
| | - Zhenni Liu
- Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, Guangdong-Hong Kong-Macao Joint Laboratory for Contaminants Exposure and Health, Institute of Environmental Health and Pollution control, Guangdong University of Technology, Guangzhou 510006, China; Guangzhou Key Laboratory of Environmental Catalysis and Pollution Control, Guangdong Engineering Technology Research Center for Photocatalytic Technology Integration and Equipment, School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, China
| | - Po Keung Wong
- Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, Guangdong-Hong Kong-Macao Joint Laboratory for Contaminants Exposure and Health, Institute of Environmental Health and Pollution control, Guangdong University of Technology, Guangzhou 510006, China; Guangzhou Key Laboratory of Environmental Catalysis and Pollution Control, Guangdong Engineering Technology Research Center for Photocatalytic Technology Integration and Equipment, School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, China
| | - Taicheng An
- Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control, Guangdong-Hong Kong-Macao Joint Laboratory for Contaminants Exposure and Health, Institute of Environmental Health and Pollution control, Guangdong University of Technology, Guangzhou 510006, China; Guangzhou Key Laboratory of Environmental Catalysis and Pollution Control, Guangdong Engineering Technology Research Center for Photocatalytic Technology Integration and Equipment, School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, China.
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8
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Acuff H, G. Aldrich C. A Review of Application Strategies and Efficacy of Probiotics in Pet Food. Vet Med Sci 2022. [DOI: 10.5772/intechopen.105829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
In companion animal nutrition, probiotics (direct-fed microbials) are marketed as functional ingredients that add value to pet foods due to the impact they have on gastrointestinal and immune health of dogs and cats. The nature of the beneficial effect each probiotic strain exerts depends on its metabolic properties and perhaps most importantly, the arrival of a sufficient number of viable cells to the large bowel of the host. Pet food manufacturing processes are designed to improve food safety and prolong shelf-life, which is counterproductive to the survival of direct-fed microbials. Therefore, a prerequisite for the effective formulation of pet foods with probiotics is an understanding of the conditions each beneficial bacterial strain needs to survive. The aims of this chapter are: (1) To summarize the inherent characteristics of probiotic strains used in commercial pet foods, and (2) To review recently published literature on the applications of probiotics to pet foods and their associated challenges to viability.
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Photocatalytic Inactivation of Bacillus subtilis Spores by Natural Sphalerite with Persulfate under Visible Light Irradiation. COATINGS 2022. [DOI: 10.3390/coatings12040528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Bacterial spores are highly resistant to be inactivated by conventional water disinfection methods. In this study, the inactivation efficiency and mechanisms of Bacillus subtitles (B. subtilis) spores by natural sphalerite (NS) with persulfate (PS) under visible light (Vis) irradiation were investigated for the first time. The NS was composed of ZnS doped with trace amounts of metal ions, including As, Fe, Cd, and Mn. The results showed that 7 log of B. subtilis spores could be completely inactivated within 5 h in the Vis/NS/PS photocatalytic system, and the inactivation efficiency was about four and seven times higher than that of the NS/PS system and the Vis/PS system, respectively. The photo-generated electrons are generated by the excitation of NS under the illumination activated PS to form PS radicals (∙SO4−) and hydroxyl radicals (∙OH), which are the main active species for spore inactivation. Mechanism studies further showed that spore inactivation was related to physiological responses, including the increase in intracellular reactive oxygen species, the change of induced antioxidant enzyme activity, and the change of total protein. Furthermore, the dynamic changes of cells during spore inactivation were observed by SEM. These results not only clarify the relationship between the cell physiological stress response and inactivation mechanism of spores, but also reveal the interaction between minerals and PS under Vis, which provides technical methods for the inactivation of bacterial spores in the field of water disinfection.
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High-Throughput Time-Lapse Fluorescence Microscopy Screening for Heterogeneously Expressed Genes in Bacillus subtilis. Microbiol Spectr 2022; 10:e0204521. [PMID: 35171018 PMCID: PMC8849057 DOI: 10.1128/spectrum.02045-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Elucidating phenotypic heterogeneity in clonal bacterial populations is important for both the fundamental understanding of bacterial behavior and the synthetic engineering of bacteria in biotechnology. In this study, we present and validate a high-throughput and high-resolution time-lapse fluorescence microscopy-based strategy to easily and systematically screen for heterogeneously expressed genes in the Bacillus subtilis model bacterium. This screen allows detection of expression patterns at high spatial and temporal resolution, which often escape detection by other approaches, and can readily be extrapolated to other bacteria. A proof-of-concept screening in B. subtilis revealed both recognized and yet unrecognized heterogeneously expressed genes, thereby validating the approach. IMPORTANCE Differential gene expression among isogenic siblings often leads to phenotypic heterogeneity and the emergence of complex social behavior and functional capacities within clonal bacterial populations. Despite the importance of such features for both the fundamental understanding and synthetic engineering of bacterial behavior, approaches to systematically map such population heterogeneity are scarce. In this context, we have elaborated a new time-lapse fluorescence microscopy-based strategy to easily and systematically screen for such heterogeneously expressed genes in bacteria with high resolution and throughput. A proof-of-concept screening in the Bacillus subtilis model bacterium revealed both recognized and yet unrecognized heterogeneously expressed genes, thereby validating our approach.
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11
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Du H, Yao W, Kulyar MFEA, Ding Y, Zhu H, Pan H, Li K, Bhutta ZA, Liu S, Li J. Effects of Bacillus amyloliquefaciens TL106 Isolated from Tibetan Pigs on Probiotic Potential and Intestinal Microbes in Weaned Piglets. Microbiol Spectr 2022; 10:e0120521. [PMID: 35080439 PMCID: PMC8791190 DOI: 10.1128/spectrum.01205-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2021] [Accepted: 12/16/2021] [Indexed: 11/20/2022] Open
Abstract
Bacillus amyloliquefaciens is a nonpathogenic microorganism whose highly active amylase is widely isolated from soil and plants. TL106 is an isolate of Bacillus amyloliquefaciens isolated from cold- and disease-resistant Tibetan pigs in Linzhi, Tibet. Here, we report that TL106 not only could survive in acidic environments, high bile salt concentrations, and high-temperature conditions but also was resistant to antibiotics. It significantly improved the growth performance of weaned piglets, especially in the prevention of diarrhea. The crude fiber and crude ash digestibility in weaned piglets after TL106 administration was considerably higher than that in other groups. The results of 16S rRNA sequencing conveyed that TL106 stabilized gut microbiota that was disturbed by the weaning process with an increased level of Lachnospiraceae, Peptococcaceae.rc4_4, Erysipelotrichaceae.L7A_E11, and Mollicutes.RF39. Hence, this study proved that Bacillus amyloliquefaciens TL106 might be a candidate for antibiotics in Duroc×Landrace×Yorkshire weaned piglets. IMPORTANCE Antibiotics are often used to promote animal growth and prevent diarrhea in weanling piglets. Nevertheless, intestinal pathogenic bacterial resistance and drug residues caused by antibiotic overuse are worthy of concern and demand an urgent solution. Bacillus amyloliquefaciens TL106 has been isolated from cold- and disease-resistant Tibetan pigs in Linzhi, Tibet. It significantly improved the growth performance, decreased diarrhea, increased the absorption of crude substances, and regulated the gut flora homeostasis in Duroc×Landrace×Yorkshire weaned piglets. As an antibiotic candidate, TL106 perfectly displayed its probiotic potential and pollution-free properties.
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Affiliation(s)
- Haitao Du
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, People’s Republic of China
- Guangxi Yangxiang co., LTD, Guigang City, Guangxi, People’s Republic of China
| | - Wangyuan Yao
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, People’s Republic of China
| | | | - Yanmei Ding
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, People’s Republic of China
| | - Huaisen Zhu
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, People’s Republic of China
| | - Huachun Pan
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, People’s Republic of China
| | - Kewei Li
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, People’s Republic of China
| | - Zeeshan Ahmad Bhutta
- The Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian, Scotland, United Kingdom
| | - Suozhu Liu
- College of Animals Husbandry and Veterinary Medicine, Tibet Agricultural and Animal Husbandry University, Linzhi, Tibet, People’s Republic China
| | - Jiakui Li
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, People’s Republic of China
- College of Animals Husbandry and Veterinary Medicine, Tibet Agricultural and Animal Husbandry University, Linzhi, Tibet, People’s Republic China
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12
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Pawluk AM, Kim D, Jin YH, Jeong KC, Mah JH. Biofilm-associated heat resistance of Bacillus cereus spores in vitro and in a food model, Cheonggukjang jjigae. Int J Food Microbiol 2021; 363:109505. [PMID: 34973549 DOI: 10.1016/j.ijfoodmicro.2021.109505] [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: 08/28/2021] [Revised: 11/19/2021] [Accepted: 12/12/2021] [Indexed: 11/15/2022]
Abstract
Bacillus cereus, a foodborne pathogen, is capable of forming spores and biofilms as methods to withstand environmental stresses. These bacterial structures are an issue for food safety as they aid the bacteria survive heat sterilisation processes of foods and food contact surfaces. This study was conducted to investigate the role of the biofilm structure in providing an extra layer of protection to spores against heat treatments. For this, heat resistance of B. cereus spores in intact biofilms was compared to that of planktonic spores in vitro and in a Cheonggukjang jjigae food model. Using methods developed in this study to measure the wet and dry heat resistance of spores in intact biofilms, it was found that B. cereus spores have significantly higher heat resistances when present in biofilms rather than as planktonic spores, and that dry heat is less effective than wet heat at killing spores in biofilms. In further detail, for wet heat treatments, spores in biofilms of the strain isolated from Cheonggukjang (Korean fermented whole soybean), B. cereus CH3, had generally higher wet heat resistances than the reference strain, B. cereus ATCC 10987, both in vitro and in the Cheonggukjang jjigae food model. However, the spores in biofilms of the two strains showed similar heat resistance to dry heat, with some exceptions, when biofilms were formed in vitro or in Cheonggukjang jjigae broth. Meanwhile, B. cereus ATCC 10987 spores in biofilms had higher or similar wet heat resistances in vitro compared to in Cheonggukjang jjigae broth. Wet heat resistances of B. cereus CH3 spores in biofilms were all statistically similar regardless of biofilm formation media (brain heart infusion and Cheonggukjang jjigae broths). For dry heat, spores in biofilms of both B. cereus strains were more heat resistant when biofilms were formed in the Cheonggukjang jjigae food model rather than in vitro. Altogether, heat resistances of spores in biofilms formed in vitro and in the food environment were found to be different depending on the tested B. cereus strain, but higher than planktonic spores in any case. This is the first study examining the heat resistance of B. cereus spores in intact biofilms matrices attached to the surface, both in vitro and in a food model. Therefore, this research is valuable to understand the protective effects of biofilms formed in food environments and to reduce the food safety risks associated with B. cereus.
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Affiliation(s)
| | - Dabin Kim
- Department of Food and Biotechnology, Korea University, Sejong 30019, Republic of Korea
| | - Young Hun Jin
- Department of Food and Biotechnology, Korea University, Sejong 30019, Republic of Korea
| | - KwangCheol Casey Jeong
- Department of Animal Sciences, University of Florida, Florida, FL 32611, USA; Emerging Pathogens Institute, University of Florida, Florida, FL 32611, USA
| | - Jae-Hyung Mah
- Department of Food and Biotechnology, Korea University, Sejong 30019, Republic of Korea.
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13
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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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14
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Shi R, Ow H, Thomas GM, Chang S, Chen H, Wang W, Yoon B. Zwitterionic Dipicolinic Acid-Based Tracers for Reservoir Surveillance Application. Ind Eng Chem Res 2021. [DOI: 10.1021/acs.iecr.1c03468] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Rena Shi
- Aramco Research Center─Boston, Aramco Services Company, 400 Technology Square, Cambridge, Massachusetts 02139, United States
| | - Hooisweng Ow
- Aramco Research Center─Boston, Aramco Services Company, 400 Technology Square, Cambridge, Massachusetts 02139, United States
| | - Gawain M. Thomas
- Aramco Research Center─Boston, Aramco Services Company, 400 Technology Square, Cambridge, Massachusetts 02139, United States
| | - Sehoon Chang
- Aramco Research Center─Boston, Aramco Services Company, 400 Technology Square, Cambridge, Massachusetts 02139, United States
| | - Hsieh Chen
- Aramco Research Center─Boston, Aramco Services Company, 400 Technology Square, Cambridge, Massachusetts 02139, United States
| | - Wei Wang
- Aramco Research Center─Boston, Aramco Services Company, 400 Technology Square, Cambridge, Massachusetts 02139, United States
| | - Bora Yoon
- Aramco Research Center─Boston, Aramco Services Company, 400 Technology Square, Cambridge, Massachusetts 02139, United States
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15
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Huang Y, Flint SH, Palmer JS. The heat resistance of spores from biofilms of Bacillus cereus grown in tryptic soy broth and milk. Int Dairy J 2021. [DOI: 10.1016/j.idairyj.2021.105169] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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16
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Amoah K, Dong XH, Tan BP, Zhang S, Kuebutornye FKA, Chi SY, Yang QH, Liu HY, Zhang HT, Yang YZ. In vitro Assessment of the Safety and Potential Probiotic Characteristics of Three Bacillus Strains Isolated From the Intestine of Hybrid Grouper ( Epinephelus fuscoguttatus♀ × Epinephelus lanceolatus♂). Front Vet Sci 2021; 8:675962. [PMID: 34124228 PMCID: PMC8193502 DOI: 10.3389/fvets.2021.675962] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 04/07/2021] [Indexed: 12/20/2022] Open
Abstract
Probiotics serving as an alternative to the criticized antibiotics mainly focus on improving animal's growth and health. After realizing the dangers posed by diseases that have led to lots of economic losses, aquaculture scientists have sought the usage of probiotics. However, most probiotics are ineffective in eliciting aquatic animals' preferred effects, since they are from non-fish sources. Again, there are even a few marine aquatic probiotics. Given this, a study was conducted to investigate the probiotic potential of the bacteria species isolated from the digestive tract of hybrid grouper (Epinephelus fuscoguttatus♀ × Epinephelus lanceolatus♂). Based on the morphological, biochemical, 16S rRNA sequencing analysis and evolutionary relationships, the isolated species were identified as Bacillus tequilensis GPSAK2 (MW548630), Bacillus velezensis GPSAK4 (MW548635), and Bacillus subtilis GPSAK9 (MW548634), which were designated as GPSAK2, GPSAK4, and GPSAK9 strains, respectively. Their probiotic potentials including their ability to tolerate high bile salt concentration, low pH, high temperatures, adhesion ability (auto-aggregation and cell-surface hydrophobicity), antimicrobial activity and biosafety test, compatibility test, hemolytic activity, and antibiotic susceptibility test were evaluated. While GPSAK2 and GPSAK9 strains were γ-hemolytic, that of GPSAK4 was α-hemolytic. All the isolates were resistant to low pH (1) and higher bile salt concentration (0.5%), showed higher viability ability after higher temperature exposure (80, 90, and 100°C), as well as higher cell-surface percentage hydrophobicity and auto-aggregation. All isolates exhibited positive compatibility with each other, signifying their ability to be used as multispecies. The three strains were susceptible to ampicillin (except GPSAK9, which was resistant), penicillin, kanamycin, ceftriaxone, chloramphenicol, erythromycin, clindamycin, furazolidone (except GPSAK2 and GPSAK9, which were moderately susceptible and resistant, respectively), polymyxin B, vancomycin (except GPSAK9, which was resistant), sulfamethoxazole (except GPSAK9, which was moderately susceptible), amikacin, minocycline, ofloxacin, norfloxacin, doxycycline, neomycin, gentamicin, tetracycline, carbenicillin, midecamycin (except GPSAK9, which was moderately susceptible), ciprofloxacin, piperacillin, and cefoperazone. All isolates demonstrated good antimicrobial activity against four pathogens, viz. Streptococcus agalactiae, Streptococcus iniae, Vibrio harveyi, and Vibrio alginolyticus. The results collectively suggest that Bacillus strains GPSAK2, GPSAK4, and GPSAK9 could serve as potential probiotic candidates that can be used to improve the growth and health status of aquatic animals, especially grouper.
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Affiliation(s)
- Kwaku Amoah
- Laboratory of Aquatic Animal Nutrition and Feed, College of Fisheries, Guangdong Ocean University, Zhanjiang, China.,Aquatic Animals Precision Nutrition and High-Efficiency Feed Engineering Research Centre of Guangdong Province, Zhanjiang, China
| | - Xiao-Hui Dong
- Laboratory of Aquatic Animal Nutrition and Feed, College of Fisheries, Guangdong Ocean University, Zhanjiang, China.,Aquatic Animals Precision Nutrition and High-Efficiency Feed Engineering Research Centre of Guangdong Province, Zhanjiang, China.,Key Laboratory of Aquatic, Livestock and Poultry Feed Science and Technology in South China, Ministry of Agriculture, Zhanjiang, China
| | - Bei-Ping Tan
- Laboratory of Aquatic Animal Nutrition and Feed, College of Fisheries, Guangdong Ocean University, Zhanjiang, China.,Aquatic Animals Precision Nutrition and High-Efficiency Feed Engineering Research Centre of Guangdong Province, Zhanjiang, China.,Key Laboratory of Aquatic, Livestock and Poultry Feed Science and Technology in South China, Ministry of Agriculture, Zhanjiang, China
| | - Shuang Zhang
- Laboratory of Aquatic Animal Nutrition and Feed, College of Fisheries, Guangdong Ocean University, Zhanjiang, China.,Aquatic Animals Precision Nutrition and High-Efficiency Feed Engineering Research Centre of Guangdong Province, Zhanjiang, China.,Key Laboratory of Aquatic, Livestock and Poultry Feed Science and Technology in South China, Ministry of Agriculture, Zhanjiang, China
| | - Felix K A Kuebutornye
- Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Animals, Zhanjiang, China
| | - Shu-Yan Chi
- Laboratory of Aquatic Animal Nutrition and Feed, College of Fisheries, Guangdong Ocean University, Zhanjiang, China.,Aquatic Animals Precision Nutrition and High-Efficiency Feed Engineering Research Centre of Guangdong Province, Zhanjiang, China.,Key Laboratory of Aquatic, Livestock and Poultry Feed Science and Technology in South China, Ministry of Agriculture, Zhanjiang, China
| | - Qi-Hui Yang
- Laboratory of Aquatic Animal Nutrition and Feed, College of Fisheries, Guangdong Ocean University, Zhanjiang, China.,Aquatic Animals Precision Nutrition and High-Efficiency Feed Engineering Research Centre of Guangdong Province, Zhanjiang, China.,Key Laboratory of Aquatic, Livestock and Poultry Feed Science and Technology in South China, Ministry of Agriculture, Zhanjiang, China
| | - Hong-Yu Liu
- Laboratory of Aquatic Animal Nutrition and Feed, College of Fisheries, Guangdong Ocean University, Zhanjiang, China.,Aquatic Animals Precision Nutrition and High-Efficiency Feed Engineering Research Centre of Guangdong Province, Zhanjiang, China.,Key Laboratory of Aquatic, Livestock and Poultry Feed Science and Technology in South China, Ministry of Agriculture, Zhanjiang, China
| | - Hai-Tao Zhang
- Key Laboratory of Aquatic, Livestock and Poultry Feed Science and Technology in South China, Ministry of Agriculture, Zhanjiang, China
| | - Yuan-Zhi Yang
- Laboratory of Aquatic Animal Nutrition and Feed, College of Fisheries, Guangdong Ocean University, Zhanjiang, China
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17
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Evelyn, Utami SP, Chairul. Effect of temperature and soluble solid on Bacillus subtilis and Bacillus licheniformis spore inactivation and quality degradation of pineapple juice. FOOD SCI TECHNOL INT 2021; 28:285-296. [PMID: 34018829 DOI: 10.1177/10820132211019143] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Bacillus subtilis and Bacillus licheniformis spores can survive processing temperatures used in the thermal processes of high-acid foods. Therefore, this study investigated the thermal inactivation of B. subtilis and B. licheniformis spores in pineapple juice at different temperatures (85-100°C) and soluble solids (SS, 11-30°Brix). The quality of juices and microbial loads after the thermal treatments during storage at 4 °C for 35 days was then checked. A linear decrease in D-value was observed with increasing temperature of treatment. Furthermore, the D-values determined in pineapple juice were: D90°C=13.2 ± 0.5 mins, D95°C = 6.8 ± 0.9 mins and D100°C = 2.1 ± 1.7 mins for B. subtilis spores, and D85°C = 16.6 ± 0.4 mins, D90°C = 7.6 ± 0.5 mins and D95°C = 3.6 ± 1.5 min, for B. licheniformis. Generally, the susceptibility of the bacteria to soluble solid change was affected by the interaction between temperature, SS and strain. In addition, pasteurization processes of ≥95°C for ≥33.8 mins was needed to ensure a recommended 5-log reduction of B. subtilis spores and limit vitamin C degradation of pineapple juice within three-week of storage at 4 °C.
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Affiliation(s)
- Evelyn
- Department of Chemical Engineering, University of Riau, Pekanbaru, Indonesia
| | - Syelvia Putri Utami
- Department of Chemical Engineering, University of Riau, Pekanbaru, Indonesia
| | - Chairul
- Department of Chemical Engineering, University of Riau, Pekanbaru, Indonesia
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18
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Tu Z, Setlow P, Brul S, Kramer G. Molecular Physiological Characterization of a High Heat Resistant Spore Forming Bacillus subtilis Food Isolate. Microorganisms 2021; 9:667. [PMID: 33807113 PMCID: PMC8005191 DOI: 10.3390/microorganisms9030667] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 03/18/2021] [Accepted: 03/20/2021] [Indexed: 02/07/2023] Open
Abstract
Bacterial endospores (spores) are among the most resistant living forms on earth. Spores of Bacillus subtilis A163 show extremely high resistance to wet heat compared to spores of laboratory strains. In this study, we found that spores of B. subtilis A163 were indeed very wet heat resistant and released dipicolinic acid (DPA) very slowly during heat treatment. We also determined the proteome of vegetative cells and spores of B. subtilis A163 and the differences in these proteomes from those of the laboratory strain PY79, spores of which are much less heat resistant. This proteomic characterization identified 2011 proteins in spores and 1901 proteins in vegetative cells of B. subtilis A163. Surprisingly, spore morphogenic protein SpoVM had no homologs in B. subtilis A163. Comparing protein expression between these two strains uncovered 108 proteins that were differentially present in spores and 93 proteins differentially present in cells. In addition, five of the seven proteins on an operon in strain A163, which is thought to be primarily responsible for this strain's spores high heat resistance, were also identified. These findings reveal proteomic differences of the two strains exhibiting different resistance to heat and form a basis for further mechanistic analysis of the high heat resistance of B. subtilis A163 spores.
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Affiliation(s)
- Zhiwei Tu
- Laboratory for Molecular Biology and Microbial Food Safety, University of Amsterdam, 1098 XH Amsterdam, The Netherlands;
- Laboratory for Mass Spectrometry of Biomolecules, University of Amsterdam, 1098 XH Amsterdam, The Netherlands;
| | - Peter Setlow
- Department of Molecular Biology and Biophysics, UCONN Health, Farmington, CT 06030-3303, USA;
| | - Stanley Brul
- Laboratory for Molecular Biology and Microbial Food Safety, University of Amsterdam, 1098 XH Amsterdam, The Netherlands;
| | - Gertjan Kramer
- Laboratory for Mass Spectrometry of Biomolecules, University of Amsterdam, 1098 XH Amsterdam, The Netherlands;
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19
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Isolation, stability, and characteristics of high-pressure superdormant Bacillus subtilis spores. Int J Food Microbiol 2021; 343:109088. [PMID: 33621831 DOI: 10.1016/j.ijfoodmicro.2021.109088] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 11/15/2020] [Accepted: 01/30/2021] [Indexed: 12/26/2022]
Abstract
Bacterial spores are a major challenge in industrial decontamination processes owing to their extreme resistance. High-pressure (HP) of 150 MPa at 37 °C can trigger the germination of spores, making them lose their extreme resistance. Once their resistance is lost, germinated spores can easily be inactivated by a mild decontamination step. The implementation of this gentle germination-inactivation strategy is hindered by the presence of a subpopulation of so-called high-pressure superdormant (HPSD) spores, which resist germination or germinate only very slowly in response to HP. It is essential to understand the properties of HPSD spores and the underlying causes of superdormancy to tackle superdormant spores and further develop germination-inactivation strategies involving HP. This study investigated factors influencing the prevalence of HPSD spores and successfully isolated them by combining buoyant density centrifugation and fluorescence-activated cell sorting, which allowed further characterisation of HPSD spores for the first time. The prevalence of HPSD spores was shown to be strongly dependent on the HP dwell time, with increasing treatment times reducing their prevalence. Spore mutants lacking major germinant receptors further showed a highly increased prevalence of HPSD spores; 93% of the spores remained dormant even after a prolonged HP dwell time of 40 min. In contrast to nutrient germination, sublethal heat treatment of 75 °C for 30 min prior to pressure treatment did not induce spore activation and increase germination. The isolated HPSD spores did not show visible structural differences compared to the initial dormant spores when investigated with transmission electron microscopy. Re-sporulated HPSD spores showed similar germination capacity compared to the initial dormant spores, indicating that HPSD spores are most likely not genetically different from the rest of the population. Moreover, the majority of HPSD spores germinated when exposed a second time to the same germination treatment; however, the germination capacity was lower than that of the initial population. The fact that the majority of spores lost superdormancy when exposed a second time to the same trigger makes it unlikely that there is one factor that determines whether a spore germinates with a certain HP treatment or not. Instead, it seems possible that there are other reversible or cumulative causes. This study investigated the factors influencing spore HP superdormancy to improve the understanding of HPSD spores with regard to their stability, germination capacity, and potential underlying causes of spore HP superdormancy. This knowledge will contribute to the development of HP-based germination-inactivation strategies for gentle but effective spore control.
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20
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Gold nanocluster-europium(III) ratiometric fluorescence assay for dipicolinic acid. Mikrochim Acta 2021; 188:26. [DOI: 10.1007/s00604-020-04667-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 11/23/2020] [Indexed: 10/22/2022]
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21
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Farag MA, Mesak MA, Saied DB, Ezzelarab NM. Uncovering the dormant food hazards, a review of foodborne microbial spores' detection and inactivation methods with emphasis on their application in the food industry. Trends Food Sci Technol 2021. [DOI: 10.1016/j.tifs.2020.10.037] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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22
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Rattray JE, Chakraborty A, Li C, Elizondo G, John N, Wong M, Radović JR, Oldenburg TBP, Hubert CRJ. Sensitive quantification of dipicolinic acid from bacterial endospores in soils and sediments. Environ Microbiol 2020; 23:1397-1406. [PMID: 33264453 PMCID: PMC8048543 DOI: 10.1111/1462-2920.15343] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 11/30/2020] [Indexed: 11/27/2022]
Abstract
Endospore-forming bacteria make up an important and numerically significant component of microbial communities in a range of settings including soils, industry, hospitals and marine sediments extending into the deep subsurface. Bacterial endospores are non-reproductive structures that protect DNA and improve cell survival during periods unfavourable for bacterial growth. An important determinant of endospores withstanding extreme environmental conditions is 2,6-pyridine dicarboxylic acid (i.e. dipicolinic acid, or DPA), which contributes heat resistance. This study presents an improved HPLC-fluorescence method for DPA quantification using a single 10-min run with pre-column Tb3+ chelation. Relative to existing DPA quantification methods, specific improvements pertain to sensitivity, detection limit and range, as well as the development of new free DPA and spore-specific DPA proxies. The method distinguishes DPA from intact and recently germinated spores, enabling responses to germinants in natural samples or experiments to be assessed in a new way. DPA-based endospore quantification depends on accurate spore-specific DPA contents, in particular, thermophilic spores are shown to have a higher DPA content, meaning that marine sediments with plentiful thermophilic spores may require spore number estimates to be revisited. This method has a wide range of potential applications for more accurately quantifying bacterial endospores in diverse environmental samples.
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Affiliation(s)
- Jayne E Rattray
- Department of Biological Sciences, University of Calgary, Calgary, T2N 1N4, Canada
| | - Anirban Chakraborty
- Department of Biological Sciences, University of Calgary, Calgary, T2N 1N4, Canada
| | - Carmen Li
- Department of Biological Sciences, University of Calgary, Calgary, T2N 1N4, Canada
| | - Gretta Elizondo
- Department of Biological Sciences, University of Calgary, Calgary, T2N 1N4, Canada
| | - Nisha John
- Department of Biological Sciences, University of Calgary, Calgary, T2N 1N4, Canada
| | - Michelle Wong
- Department of Biological Sciences, University of Calgary, Calgary, T2N 1N4, Canada
| | - Jagoš R Radović
- Department of Geoscience, University of Calgary, Calgary, T2N 1N4, Canada
| | | | - Casey R J Hubert
- Department of Biological Sciences, University of Calgary, Calgary, T2N 1N4, Canada
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23
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Soni A, Smith J, Archer R, Gardner A, Tong K, Brightwell G. Development of Bacterial Spore Pouches as a Tool to Evaluate the Sterilization Efficiency-A Case Study with Microwave Sterilization Using Clostridium sporogenes and Geobacillus stearothermophilus. Foods 2020; 9:E1342. [PMID: 32977443 PMCID: PMC7598248 DOI: 10.3390/foods9101342] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 09/18/2020] [Accepted: 09/20/2020] [Indexed: 11/16/2022] Open
Abstract
In this study, novel spore pouches were developed using mashed potato as a food model inoculated with either Geobacillus stearothermophilus or Clostridium sporogenes spores. These spore pouches were used to evaluate the sterilization efficiency of Coaxially induced microwave pasteurization and sterilization (CiMPAS) as a case study. CiMPAS technology combines microwave energy (915 MHz) along with hot water immersion to sterilize food in polymeric packages. The spore pouches were placed at pre-determined specific locations, especially cold spots in each food tray before being processed using two regimes (R-121 and R-65), which consisted of 121 °C and 65 °C at 12 and 22 kW, respectively, followed by recovery and enumeration of the surviving spores. To identify cold spots or the location for inoculation, mashed potato was spiked with Maillard precursors and processed through CiMPAS, followed by measurement of lightness values (*L-values). Inactivation equivalent to of 1-2 Log CFU/g and >6 Log CFU/g for Geobacillus stearothermophilus and Clostridium sporogenes spores, respectively was obtained on the cold spots using R-121, which comprised of a total processing time of 64.2 min. Whereas, inactivation of <1 and 2-3 Log CFU/g for G. stearothermophilus and C. sporogenes spores, respectively on the cold spots was obtained using R-65 (total processing time of 68.3 min), whereas inactivation of 1-3 Log CFU/g of C. sporogenes spores was obtained on the sides of the tray. The results were reproducible across three processing replicates for each regime and inactivation at the specific locations were clearly distinguishable. The study indicated a strong potential to use spore pouches as a tool for validation studies of microwave-induced sterilization.
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Affiliation(s)
- Aswathi Soni
- Food Assurance, AgResearch, Palmerston North 4410, New Zealand; (A.G.); (G.B.)
| | - Jeremy Smith
- School of Food & Advanced Technology, Massey University, Palmerston North 4410, New Zealand; (J.S.); (R.A.); (K.T.)
| | - Richard Archer
- School of Food & Advanced Technology, Massey University, Palmerston North 4410, New Zealand; (J.S.); (R.A.); (K.T.)
| | - Amanda Gardner
- Food Assurance, AgResearch, Palmerston North 4410, New Zealand; (A.G.); (G.B.)
| | - Kris Tong
- School of Food & Advanced Technology, Massey University, Palmerston North 4410, New Zealand; (J.S.); (R.A.); (K.T.)
| | - Gale Brightwell
- Food Assurance, AgResearch, Palmerston North 4410, New Zealand; (A.G.); (G.B.)
- New Zealand Food Safety Science Research Centre, Palmerston North 4410, New Zealand
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Abstract
This study demonstrated the progress of macromolecular synthesis during Bacillus subtilis spore germination and outgrowth. The transcriptome analysis has additionally allowed us to trace gene expression during this transformation process. For the first time, the basic survival kit for spore-based life has been identified. In addition, in this analysis based on monitoring of protein levels in germinating and outgrowing spores, the transition from (ribo)nucleotide and amino acid biosynthesis to the restoration of all metabolic pathways can be clearly seen. The integrative multi-omics approach applied in this study thus has helped us to achieve a comprehensive overview of the molecular mechanisms at the basis of spore germination and outgrowth as well as to identify important knowledge gaps in need of further study. Bacillus subtilis spores can reactivate their metabolism through germination upon contact with germinants and can develop into vegetative cells upon outgrowth. However, the mechanisms at the basis of the molecular machinery that triggers the spore germination and outgrowth processes are still largely unclear. To gain further insights into these processes, the transcriptome and proteome changes occurring during the conversion of spores to vegetative cells were analyzed in the present study. For each time point sampled, the changes in the spore proteome were quantitatively monitored relative to the proteome of metabolically 15N-labeled vegetative cells. Of the quantified proteins, 60% are shared by vegetative cells and spores, indicating that the spores have a minimal protein set, sufficient to resume metabolism upon completion of germination. These shared proteins thus represent the most basic “survival kit” for spore-based life. We observed no significant change in the proteome or the transcriptome until the spore’s completion of germination. Our analysis identified 34 abundant mRNA transcripts in the dormant spores, 31 of which are rapidly degraded after germination. In outgrowing spores, we identified 3,152 differentially expressed genes and have demonstrated the differential expression of 322 proteins with our mass spectrometry analyses. Our data also showed that 173 proteins from dormant spores, including both proteins unique to spores and proteins shared with vegetative cells, were lost after completion of germination. The observed diverse timings of synthesis of different protein sets in spore outgrowth revealed a putative core strategy underlying the revival of ‘life’ from the B. subtilis spore. IMPORTANCE This study demonstrated the progress of macromolecular synthesis during Bacillus subtilis spore germination and outgrowth. The transcriptome analysis has additionally allowed us to trace gene expression during this transformation process. For the first time, the basic survival kit for spore-based life has been identified. In addition, in this analysis based on monitoring of protein levels in germinating and outgrowing spores, the transition from (ribo)nucleotide and amino acid biosynthesis to the restoration of all metabolic pathways can be clearly seen. The integrative multi-omics approach applied in this study thus has helped us to achieve a comprehensive overview of the molecular mechanisms at the basis of spore germination and outgrowth as well as to identify important knowledge gaps in need of further study.
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Tu Z, R. Abhyankar W, N. Swarge B, van der Wel N, Kramer G, Brul S, J. de Koning L. Artificial Sporulation Induction (ASI) by kinA Overexpression Affects the Proteomes and Properties of Bacillus subtilis Spores. Int J Mol Sci 2020; 21:ijms21124315. [PMID: 32560401 PMCID: PMC7352945 DOI: 10.3390/ijms21124315] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 06/07/2020] [Accepted: 06/16/2020] [Indexed: 12/15/2022] Open
Abstract
To facilitate more accurate spore proteomic analysis, the current study focuses on inducing homogeneous sporulation by overexpressing kinA and assesses the effect of synchronized sporulation initiation on spore resistance, structures, the germination behavior at single-spore level and the proteome. The results indicate that, in our set up, the sporulation by overexpressing kinA can generate a spore yield of 70% within 8 h. The procedure increases spore wet heat resistance and thickness of the spore coat and cortex layers, whilst delaying the time to spore phase-darkening and burst after addition of germinant. The proteome analysis reveals that the upregulated proteins in the kinA induced spores, compared to spores without kinA induction, as well as the 'wildtype' spores, are mostly involved in spore formation. The downregulated proteins mostly belong to the categories of coping with stress, carbon and nitrogen metabolism, as well as the regulation of sporulation. Thus, while kinA overexpression enhances synchronicity in sporulation initiation, it also has profound effects on the central equilibrium of spore formation and spore germination, through modulation of the spore molecular composition and stress resistance physiology.
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Affiliation(s)
- Zhiwei Tu
- Laboratory for Molecular Biology and Microbial Food Safety, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands; (Z.T.); (W.R.A.); (B.N.S.)
- Laboratory for Mass Spectrometry of Biomolecules, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands; (G.K.); (L.J.d.K.)
| | - Wishwas R. Abhyankar
- Laboratory for Molecular Biology and Microbial Food Safety, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands; (Z.T.); (W.R.A.); (B.N.S.)
- Laboratory for Mass Spectrometry of Biomolecules, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands; (G.K.); (L.J.d.K.)
| | - Bhagyashree N. Swarge
- Laboratory for Molecular Biology and Microbial Food Safety, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands; (Z.T.); (W.R.A.); (B.N.S.)
- Laboratory for Mass Spectrometry of Biomolecules, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands; (G.K.); (L.J.d.K.)
| | - Nicole van der Wel
- Department of Medical Biology, Electron Microscopy Centre Amsterdam, Amsterdam University Medical Centers, University of Amsterdam, 1100 DD Amsterdam, The Netherlands;
| | - Gertjan Kramer
- Laboratory for Mass Spectrometry of Biomolecules, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands; (G.K.); (L.J.d.K.)
| | - Stanley Brul
- Laboratory for Molecular Biology and Microbial Food Safety, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands; (Z.T.); (W.R.A.); (B.N.S.)
- Correspondence: ; Tel.: +31-20-525-7079 (ext. 6970)
| | - Leo J. de Koning
- Laboratory for Mass Spectrometry of Biomolecules, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands; (G.K.); (L.J.d.K.)
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Harirchi S, Etemadifar Z, Mahboubi A, Yazdian F, Taherzadeh MJ. The Effect of Calcium/Magnesium Ratio on the Biomass Production of a Novel Thermoalkaliphilic Aeribacillus pallidus Strain with Highly Heat-Resistant Spores. Curr Microbiol 2020; 77:2565-2574. [PMID: 32361845 DOI: 10.1007/s00284-020-02010-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2019] [Accepted: 04/24/2020] [Indexed: 12/29/2022]
Abstract
Hot springs are fascinating extreme environments for the isolation of polyextremophilic microorganisms with extraordinary characteristics. Since polyextremophilic bacterial growth are not as high as routine bacteria, the objective of this study was to investigate the effect of some environmental factors on biomass and metabolites productions in the newly isolated strain, from Larijan hot spring in Iran. The strain was identified as Aeribacillus pallidus Lhs-10 and deposited as CCUG 72355 and IBRC-M 11202 in Sweden and Iran, respectively. This thermoalkaliphilic strain can grow best at 50 °C, pH 8 and in the presence of 25 g/l NaCl. The physiological characterization of this strain show that [Ca/Mg] ratio affect its growth and biomass production with the best results obtained at the ratio of 2.5. Moreover, lactic and acetic acids production by this strain was affected by pH, aeration, and temperature, where a metabolic shift was detected from lactate to acetate production when the culture was aerated. Besides, its spores could tolerate heating at 80, 85, 90, 95 and 98 °C for 30 min without any reduction in the initial spore population, whereas D-value was defined 50 min at 98 °C. This newly lactic acid-producing strain of A. pallidus can be a promising strain that can be used in the harsh conditions in industrial processes.
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Affiliation(s)
- Sharareh Harirchi
- Department of Cell and Molecular Biology & Microbiology, Faculty of Biological Science and Technology, University of Isfahan, 8174673441, Isfahan, Iran
| | - Zahra Etemadifar
- Department of Cell and Molecular Biology & Microbiology, Faculty of Biological Science and Technology, University of Isfahan, 8174673441, Isfahan, Iran.
| | - Amir Mahboubi
- Swedish Centre for Resource Recovery, University of Borås, 501 90, Borås, Sweden
| | - Fatemeh Yazdian
- Department of Life Science Engineering, Faculty of New Sciences and Technologies, University of Tehran, Tehran, Iran
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Kim SS, Kim SH, Park SH, Kang DH. Inactivation of Bacillus cereus Spores on Stainless Steel by Combined Superheated Steam and UV-C Irradiation Treatment. J Food Prot 2020; 83:13-16. [PMID: 31804873 DOI: 10.4315/0362-028x.jfp-19-133] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Bacillus cereus spore contamination on food contact surfaces is of great concern in the food industry. Thus, in the present study, superheated steam (SHS) was used alone or combined with UV-C irradiation for inactivation of B. cereus spores inoculated on stainless steel coupons. Temperatures higher than 250°C were needed to effectively inactivate B. cereus spores by SHS treatment alone, while a synergistic bactericidal effect resulted from the sequential treatment of SHS before or after UV-C irradiation. The increased dipicolinic acid ratio obtained by the combined treatment had a significant role in the synergistic bactericidal effect. Therefore, the combined treatment of SHS and UV-C could be used effectively to inactivate B. cereus on stainless steel. It is recommended to use hurdle technology with reduced energy consumption to ensure microbiological safety on food contact surfaces.
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Affiliation(s)
- Sang-Soon Kim
- Department of Food Engineering, Dankook University, Cheonan, Chungnam 31116, Republic of Korea
| | - Soo-Hwan Kim
- Department of Agricultural Biotechnology, Center for Food and Bioconvergence, and Research Institute for Agricultural and Life Sciences, Seoul National University, Seoul 08826, Republic of Korea
| | - Sang-Hyun Park
- Department of Food Science and Technology, Kongju National University, Yesan, Chungnam 32439, Republic of Korea
| | - Dong-Hyun Kang
- Department of Agricultural Biotechnology, Center for Food and Bioconvergence, and Research Institute for Agricultural and Life Sciences, Seoul National University, Seoul 08826, Republic of Korea.,Institutes of Green Bio Science & Technology, Seoul National University, Pyeongchang-gun, Gangwon do, 25354, Republic of Korea
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Chen H, Shi R, Ow H. Predicting Stability Constants for Terbium(III) Complexes with Dipicolinic Acid and 4-Substituted Dipicolinic Acid Analogues using Density Functional Theory. ACS OMEGA 2019; 4:20665-20671. [PMID: 31858052 PMCID: PMC6906780 DOI: 10.1021/acsomega.9b02851] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 11/14/2019] [Indexed: 06/10/2023]
Abstract
The relative stability constants of Tb(III) complexes exhibiting binding to a series of 4-substituted analogues of dipicolinic acid (2,6-pyridinedicarboxylic acid) (DPA) were calculated using density functional theory (DFT) with the standard thermodynamic cycle. DFT calculations showed that the strengths of the stability constants were modified by the substituents in the following (decreasing) order: -NH2 > -OH ∼ -CH2OH > -imidazole ∼ -Cl ∼ -Br ∼ -H > -F > -I, with the differences among them falling within one to two log units except for -NH2. Through population and structural analysis, we observed that the -NH2, -OH, -CH2OH, and halide substituents can donate electrons via resonance effect to the pyridine ring of DPA while inductively withdrawing electrons with different strengths, thus resulting in the different binding strengths of the 4-substituted DPAs to the Tb(III) ions. We believe that these observations possess utility not only in the ongoing development of luminescent probes for bioanalytical studies but also for more recent cross-industrial efforts to enhance reservoir surveillance capabilities using chemical tracers within the oil and gas sector.
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Song S, Wang X, Xu K, Ning L, Yang X. Rapid identification and quantitation of the viable cells of Lactobacillus casei in fermented dairy products using an aptamer-based strategy powered by a novel cell-SELEX protocol. J Dairy Sci 2019; 102:10814-10824. [DOI: 10.3168/jds.2019-16693] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Accepted: 08/08/2019] [Indexed: 01/12/2023]
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Webb MD, Barker GC, Goodburn KE, Peck MW. Risk presented to minimally processed chilled foods by psychrotrophic Bacillus cereus. Trends Food Sci Technol 2019; 93:94-105. [PMID: 31764911 PMCID: PMC6853023 DOI: 10.1016/j.tifs.2019.08.024] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 08/19/2019] [Accepted: 08/29/2019] [Indexed: 11/13/2022]
Abstract
BACKGROUND Spores of psychrotrophic Bacillus cereus may survive the mild heat treatments given to minimally processed chilled foods. Subsequent germination and cell multiplication during refrigerated storage may lead to bacterial concentrations that are hazardous to health. SCOPE AND APPROACH This review is concerned with the characterisation of factors that prevent psychrotrophic B. cereus reaching hazardous concentrations in minimally processed chilled foods and associated foodborne illness. A risk assessment framework is used to quantify the risk associated with B. cereus and minimally processed chilled foods. KEY FINDINGS AND CONCLUSIONS Bacillus cereus is responsible for two types of food poisoning, diarrhoeal (an infection) and emetic (an intoxication); however, no reported outbreaks of food poisoning have been associated with B. cereus and correctly stored commercially-produced minimally processed chilled foods. In the UK alone, more than 1010 packs of these foods have been sold in recent years without reported illness, thus the risk presented is very low. Further quantification of the risk is merited, and this requires additional data. The lack of association between diarrhoeal food poisoning and correctly stored commercially-produced minimally processed chilled foods indicates that an infectious dose has not been reached. This may reflect low pathogenicity of psychrotrophic strains. The lack of reported association of psychrotrophic B. cereus with emetic illness and correctly stored commercially-produced minimally processed chilled foods indicates that a toxic dose of the emetic toxin has not been formed. Laboratory studies show that strains form very small quantities of emetic toxin at chilled temperatures.
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Affiliation(s)
- Martin D. Webb
- Quadram Institute Bioscience, Norwich Research Park, Norwich, NR4 7UQ, UK
| | - Gary C. Barker
- Quadram Institute Bioscience, Norwich Research Park, Norwich, NR4 7UQ, UK
| | - Kaarin E. Goodburn
- Chilled Food Associates, c/o 3 Weekley Wood Close, Kettering, NN14 1UQ, UK
| | - Michael W. Peck
- Quadram Institute Bioscience, Norwich Research Park, Norwich, NR4 7UQ, UK
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The Copy Number of the spoVA 2mob Operon Determines Pressure Resistance of Bacillus Endospores. Appl Environ Microbiol 2019; 85:AEM.01596-19. [PMID: 31375487 DOI: 10.1128/aem.01596-19] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Accepted: 07/27/2019] [Indexed: 12/27/2022] Open
Abstract
The spoVA 2mob operon confers heat resistance to Bacillus spp., and the resistance correlates to the copy number of the operon. Bacillus endospores also exhibit a strong variation in resistance to pressure, but the underlying mechanisms of endospore resistance to pressure are not fully understood. We determined the effects of multiple spoVA 2mob operons on high-pressure resistance in Bacillus endospores. The copy numbers of the spoVA 2mob operon in 17 strains of Bacillus subtilis, Bacillus amyloliquefaciens, Bacillus cereus, Bacillus velezensis, and Bacillus pumilus were determined via droplet digital PCR (ddPCR) and genome sequencing. These strains contained between 0 and 3 copies of the spoVA 2mob operon; the quantification of the gene copy number by ddPCR was as accurate as whole-genome sequencing. We further tested the pressure resistance of 17 Bacillus endospores at 600 MPa and 80°C. Strains with one or no spoVA 2mob operon had significantly lower pressure resistance than strains with two or three copies of the operons (P < 0.001), indicating that redundant spoVA 2mob operons in Bacillus contributed to higher pressure resistance of endospores. The copy number of the spoVA 2mob operon was not related to the dipicolinic acid (DPA) content of endospores. Overall, the copy number of the spoVA 2mob operon contributes to pressure resistance of Bacillus endospores. This improves our understanding of the pressure resistance mechanisms in Bacillus spp. and may inform the development of high-pressure sterilization in food processing.IMPORTANCE Bacillus spp. are considered pressure-resistant microorganisms, but the resistance mechanisms remain unknown. The spoVA 2mob operon is a mobile genetic element, and it can transfer to pathogenic or spoilage organisms by horizontal gene transfer. Results in this study indicate that multiple copies of the spoVA 2mob operon mediate high-pressure resistance of Bacillus endospores, and it might contribute to the identification of the source of pressure-resistant pathogens and spoilage organisms that may contaminate the food supply. The droplet digital PCR (ddPCR) system is well suited for analysis in some human diseases due to its high efficiency and capability to provide high precision; however, no relevant studies in food microbiology have been reported so far. This study demonstrates a novel application of ddPCR in food microbiology.
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Liang R, Lau MCY, Baars O, Robb FT, Onstott TC. Aspartic acid racemization constrains long-term viability and longevity of endospores. FEMS Microbiol Ecol 2019; 95:5553460. [DOI: 10.1093/femsec/fiz132] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 08/20/2019] [Indexed: 11/12/2022] Open
Abstract
ABSTRACT
Certain microorganisms survive long periods of time as endospores to cope with adverse conditions. Since endospores are metabolically inactive, the extent of aspartic acid (Asp) racemization will increase over time and might kill the spores by preventing their germination. Therefore, understanding the relationship between endospore survivability and Asp racemization is important for constraining the long-term survivability and global dispersion of spore-forming bacteria in nature. Geobacillus stearothermophilus was selected as a model organism to investigate racemization kinetics and survivability of its endospores at 65°C, 75°C and 98°C. This study found that the Asp racemization rates of spores and autoclaved spores were similar at all temperatures. The Asp racemization rate of spores was not significantly different from that of vegetative cells at 65°C. The Asp racemization rate of G. stearothermophilus spores was not significantly different from that of Bacillus subtilis spores at 98°C. The viability of spores and vegetative cells decreased dramatically over time, and the mortality of spores correlated exponentially with the degree of racemization (R2 = 0.9). This latter correlation predicts spore half-lives on the order of hundreds of years for temperatures typical of shallow marine sediments, a result consistent with studies about the survivability of thermophilic spores found in these environments.
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Affiliation(s)
- Renxing Liang
- Department of Geosciences, Princeton University, Princeton, NJ, 08544, USA
| | - Maggie C Y Lau
- Department of Geosciences, Princeton University, Princeton, NJ, 08544, USA
| | - Oliver Baars
- Department of Geosciences, Princeton University, Princeton, NJ, 08544, USA
| | - Frank T Robb
- Department of Microbiology and Immunology, University of Maryland, Baltimore, MD, 21202, USA
| | - Tullis C Onstott
- Department of Geosciences, Princeton University, Princeton, NJ, 08544, USA
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Schottroff F, Pyatkovskyy T, Reineke K, Setlow P, Sastry SK, Jaeger H. Mechanisms of enhanced bacterial endospore inactivation during sterilization by ohmic heating. Bioelectrochemistry 2019; 130:107338. [PMID: 31377394 DOI: 10.1016/j.bioelechem.2019.107338] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 07/24/2019] [Accepted: 07/24/2019] [Indexed: 02/06/2023]
Abstract
During ohmic heating, the electric field may additionally inactivate bacterial endospores. However, the exact mechanism of action is unclear. Thus, a mechanistic study was carried out, investigating the possible target of electric fields inside the spore. Bacillus subtilis spores were heated by conventional and ohmic heating in a capillary system under almost identical thermal conditions. Wild-type (PS533) spores were used, as well as isogenic mutants lacking certain components known for their contribution to spores' heat resistance: small-acid soluble proteins (SASP) protecting DNA (PS578); the coat covering the spore (PS3328); and the spore germination enzyme SleB (FB122(+)). Treatment-dependent release of the spore core's depot of dipicolinic acid (DPA) was further evaluated. Up to 2.4 log10 additional inactivation of PS533 could be achieved by ohmic heating, compared to conventional heating. The difference varied for the mutants, with a decreasing difference indicating a decreased effect of the electric field and vice versa. In particular, mutant spores lacking SASPs showed a behavior more similar to thermal inactivation alone. The combination of heat and electric field was shown to be necessary for enhanced spore inactivation. Thus, it is hypothesized that either the heat treatment makes the spore susceptible to the electric field, or vice versa.
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Affiliation(s)
- Felix Schottroff
- Institute of Food Technology, University of Natural Resources and Life Sciences (BOKU), Vienna, Austria; Department of Food, Agricultural and Biological Engineering, Ohio State University, Columbus, OH, USA.
| | - Taras Pyatkovskyy
- Department of Food, Agricultural and Biological Engineering, Ohio State University, Columbus, OH, USA
| | | | - Peter Setlow
- Department of Molecular Biology and Biophysics, UCONN Health, Farmington, CT, USA
| | - Sudhir K Sastry
- Department of Food, Agricultural and Biological Engineering, Ohio State University, Columbus, OH, USA
| | - Henry Jaeger
- Institute of Food Technology, University of Natural Resources and Life Sciences (BOKU), Vienna, Austria
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Mawatari KI, Atsumi M, Nakamura F, Yasuda M, Fukuuchi T, Yamaoka N, Kaneko K, Nakagomi K, Oku N. Determination of Dipicolinic Acid in "Natto" by High-Performance Liquid Chromatography Coupled With Postcolumn Photoirradiation With Zinc Acetate. Int J Tryptophan Res 2019; 12:1178646919852120. [PMID: 31258330 PMCID: PMC6585242 DOI: 10.1177/1178646919852120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 04/22/2019] [Indexed: 11/16/2022] Open
Abstract
A system was developed for determining dipicolinic acid in “natto” using liquid chromatography with fluorometric detection. The compound was separated by reversed-phase chromatography using a mobile phase of 0.1 mol/L disodium hydrogen phosphate, 0.05 mol/L citric acid buffer (adjusted to pH 3.0) containing 3.0 mmol/L zinc acetate and 35 mmol/L perchloric acid. The compound in the column effluent was irradiated with ultraviolet light to produce fluorescence. This fluorescence was monitored at an excitation at 336 nm and an emission at 448 nm. The calibration curve for dipicolinic acid was observed to be linear in a range of 0.2 to 112 ng. The dipicolinic acid content of natto was 7.24 ± 0.54 mg/100 g (wet weight, mean ± standard deviation [SD], n = 6).
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Affiliation(s)
- Ken-Ichi Mawatari
- Department of Bioanalytical Chemistry, Faculty of Pharma-Science, Teikyo University, Tokyo, Japan
| | - Motomasa Atsumi
- Department of Bioanalytical Chemistry, Faculty of Pharma-Science, Teikyo University, Tokyo, Japan
| | - Fumiya Nakamura
- Department of Bioanalytical Chemistry, Faculty of Pharma-Science, Teikyo University, Tokyo, Japan
| | - Makoto Yasuda
- Department of Bioanalytical Chemistry, Faculty of Pharma-Science, Teikyo University, Tokyo, Japan
| | - Tomoko Fukuuchi
- Department of Bioanalytical Chemistry, Faculty of Pharma-Science, Teikyo University, Tokyo, Japan
| | - Noriko Yamaoka
- Department of Bioanalytical Chemistry, Faculty of Pharma-Science, Teikyo University, Tokyo, Japan
| | - Kiyoko Kaneko
- Department of Bioanalytical Chemistry, Faculty of Pharma-Science, Teikyo University, Tokyo, Japan
| | - Kazuya Nakagomi
- Department of Bioanalytical Chemistry, Faculty of Pharma-Science, Teikyo University, Tokyo, Japan
| | - Naoto Oku
- Department of Bioanalytical Chemistry, Faculty of Pharma-Science, Teikyo University, Tokyo, Japan
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Ebrahimi A, Csonka LN, Alam MA. Analyzing Thermal Stability of Cell Membrane of Salmonella Using Time-Multiplexed Impedance Sensing. Biophys J 2019; 114:609-618. [PMID: 29414707 DOI: 10.1016/j.bpj.2017.10.032] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 09/12/2017] [Accepted: 10/17/2017] [Indexed: 01/16/2023] Open
Abstract
Heat treatment is one of the most widely used methods for inactivation of bacteria in food products. Heat-induced loss of bacterial viability has been variously attributed to protein denaturation, oxidative stress, or membrane leakage; indeed, it is likely to involve a combination of these processes. We examine the effect of mild heat stress (50-55°C for ≤12 min) on cell permeability by directly measuring the electrical conductance of samples of Salmonella enterica serovar Typhimurium to answer a fundamental biophysical question, namely, how bacteria die under mild heat stress. Our results show that when exposed to heat shock, the cell membrane is damaged and cells die mainly due to the leakage of small cytoplasmic species to the surrounding media without lysis (confirmed by fluorescent imaging). We measured the conductance change, ΔY, of wild-type versus genetically modified heat-resistant (HR) cells in response to pulse and ramp heating profiles with different thermal time constants. In addition, we developed a phenomenological model to correlate the membrane damage, cytoplasmic leakage, and cell viability. This model traces the differential viability and ΔY of wild-type and HR cells to the difference in the effective activation energies needed to permeabilize the cells, implying that HR cells are characterized by stronger lateral interactions between molecules, such as lipids, in their cell envelope.
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Affiliation(s)
- Aida Ebrahimi
- School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana; Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana
| | - Laszlo N Csonka
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana
| | - Muhammad A Alam
- School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana; Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana.
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Characterization of the virulence of a non-RT027, non-RT078 and binary toxin-positive Clostridium difficile strain associated with severe diarrhea. Emerg Microbes Infect 2018; 7:211. [PMID: 30542069 PMCID: PMC6291415 DOI: 10.1038/s41426-018-0211-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 11/01/2018] [Accepted: 11/11/2018] [Indexed: 02/06/2023]
Abstract
The expression of the Clostridium difficile binary toxin CDT is generally observed in the RT027 (ST1) and RT078 (ST11) C. difficile isolates, which are associated with severe C. difficile infection (CDI). However, we recently reported that the non-RT027 and non-RT078 C. difficile strain LC693 (TcdA+TcdB+ CDT+, ST201) caused severe diarrhea in a patient in Xiangya Hospital in China. C.difficile LC693 is a member of Clade 3, and in this study, we identified LC693 as RT871 and compared its virulence and pathogenicity to those of C.difficile R20291 (TcdA+TcdB+CDT+, ST1/RT027), UK6 (TcdA+TcdB+CDT+, ST35/RT027), CD630 (TcdA+TcdB+CDT−, ST54, RT012), and 1379 (TcdA+TcdB+CDT−, ST54/RT012), with strain 1379 being an epidemic C.difficile isolate from the same hospital. LC693 displayed a higher sporulation rate than R20291, CD630 or strain 1379. LC693 was comparable to R20291 with respect to spore germination, motility, and biofilm formation, but showed a faster germination rate, higher motility and a higher biofilm formation capability compared to CD630 and strain 1379. The adherence of spores to human gut epithelial cells was similar for all strains.The total toxin release of LC693 was lower than that of R20291, but higher than that of CD630 and strain 1379. Finally, in a mouse model of CDI, LC693 was capable of causing moderate to severe disease. Our findings demonstrate the pathogenicity of non-RT027 and non-RT078 binary toxin-positive C. difficile strains. Furthermore, our data indicate that LC693 may be more virulent than strain 1379, an epidemic strain from the same hospital, and provide the first phenotypic characterization of a non-RT027 and non-RT078 binary toxin-positive ST201 isolate.
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Daqu Fermentation Selects for Heat-Resistant Enterobacteriaceae and Bacilli. Appl Environ Microbiol 2018; 84:AEM.01483-18. [PMID: 30120119 DOI: 10.1128/aem.01483-18] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2018] [Accepted: 08/15/2018] [Indexed: 11/20/2022] Open
Abstract
Daqu is a spontaneous solid-state cereal fermentation used as saccharification and starter culture in Chinese vinegar and liquor production. The evolution of microbiota in this spontaneous fermentation is controlled by the temperature profile, which reaches temperatures from 50 to 65°C for several days. Despite these high temperatures, mesophilic Enterobacteriaceae (including Cronobacter) and bacilli are present throughout Daqu fermentation. This study aimed to determine whether Daqu spontaneous solid-state fermentation selects for heat-resistant variants of these organisms. Heat resistance in Enterobacteriaceae is mediated by the locus of heat resistance (LHR). One LHR-positive strain of Kosakonia cowanii was identified in Daqu, and it exhibited higher heat resistance than the LHR-negative K. cowanii isolated from malted oats. Heat resistance in Bacillus endospores is mediated by the spoVA 2mob operon. Out of 10 Daqu isolates of the species Bacillus licheniformis, Brevibacillus parabrevis, Bacillus subtilis, Bacillus amyloliquefaciens, and Bacillus velezensis, 5 did not contain spoVA 2mob, 3 contained one copy, and 2 contained two copies. The presence and copy number of the spoVA 2mob operon increased the resistance of spores to treatment with 110°C. To confirm the selection of LHR- and spoVA 2mob-positive strains during Daqu fermentation, the copy numbers of these genetic elements in Daqu samples were quantified by quantitative PCR (qPCR). The abundance of LHR and the spoVA 2mob operon in community DNA relative to that of total bacterial 16S rRNA genes increased 3-fold and 5-fold, respectively, during processing. In conclusion, culture-dependent and culture-independent analyses suggest that Daqu fermentation selects for heat-resistant Enterobacteriaceae and bacilli.IMPORTANCE Daqu fermentations select for mobile genetic elements conferring heat resistance in Enterobacteriaceae and bacilli. The locus of heat resistance (LHR), a genomic island conferring heat resistance in Enterobacteriaceae, and the spoVA 2mob operon, conferring heat resistance on bacterial endospores, were enriched 3- to 5-fold during Daqu fermentation and maturation. It is therefore remarkable that the LHR and the spoVA 2mob operon are accumulated in the same food fermentation. The presence of heat-resistant Kosakonia spp. and Bacillus spp. in Daqu is not of concern for food safety; however, both genomic islands are mobile and transferable to pathogenic bacteria or toxin-producing bacteria by horizontal gene transfer. The identification of the LHR and the spoVA 2mob operon as indicators of fitness of Enterobacteriaceae and bacilli in Daqu fermentation provides insights into environmental sources of heat-resistant organisms that may contaminate the food supply.
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Swarge BN, Roseboom W, Zheng L, Abhyankar WR, Brul S, de Koster CG, de Koning LJ. "One-Pot" Sample Processing Method for Proteome-Wide Analysis of Microbial Cells and Spores. Proteomics Clin Appl 2018; 12:e1700169. [PMID: 29484825 PMCID: PMC6174930 DOI: 10.1002/prca.201700169] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Revised: 01/22/2018] [Indexed: 11/15/2022]
Abstract
PURPOSE Bacterial endospores, the transmissible forms of pathogenic bacilli and clostridia, are heterogeneous multilayered structures composed of proteins. These proteins protect the spores against a variety of stresses, thus helping spore survival, and assist in germination, by interacting with the environment to form vegetative cells. Owing to the complexity, insolubility, and dynamic nature of spore proteins, it has been difficult to obtain their comprehensive protein profiles. EXPERIMENTAL DESIGN The intact spores of Bacillus subtilis, Bacillus cereus, and Peptoclostridium difficile and their vegetative counterparts were disrupted by bead beating in 6 m urea under reductive conditions. The heterogeneous mixture was then double digested with LysC and trypsin. Next, the peptide mixture was pre-fractionated with zwitterionic hydrophilic interaction liquid chromatography (ZIC-HILIC) followed by reverse-phase LC-FT-MS analysis of the fractions. RESULTS "One-pot" method is a simple, robust method that yields identification of >1000 proteins with high confidence, across all spore layers from B. subtilis, B. cereus, and P. difficile. CONCLUSIONS AND MEDICAL RELEVANCE This method can be employed for proteome-wide analysis of non-spore-forming as well as spore-forming pathogens. Analysis of spore protein profile will help to understand the sporulation and germination processes and to distinguish immunogenic protein markers.
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Affiliation(s)
- Bhagyashree Nandakishor Swarge
- Department of Mass Spectrometry of Bio macromolecules, University of Amsterdam, Amsterdam, The Netherlands
- Department of Molecular Biology and Microbial Food Safety, Swammerdam Institutes of Life Sciences, University of Amsterdam, The Netherlands
| | - Winfried Roseboom
- Department of Mass Spectrometry of Bio macromolecules, University of Amsterdam, Amsterdam, The Netherlands
| | - Linli Zheng
- Department of Mass Spectrometry of Bio macromolecules, University of Amsterdam, Amsterdam, The Netherlands
- Department of Molecular Biology and Microbial Food Safety, Swammerdam Institutes of Life Sciences, University of Amsterdam, The Netherlands
| | - Wishwas R Abhyankar
- Department of Mass Spectrometry of Bio macromolecules, University of Amsterdam, Amsterdam, The Netherlands
- Department of Molecular Biology and Microbial Food Safety, Swammerdam Institutes of Life Sciences, University of Amsterdam, The Netherlands
| | - Stanley Brul
- Department of Molecular Biology and Microbial Food Safety, Swammerdam Institutes of Life Sciences, University of Amsterdam, The Netherlands
| | - Chris G de Koster
- Department of Mass Spectrometry of Bio macromolecules, University of Amsterdam, Amsterdam, The Netherlands
| | - Leo J de Koning
- Department of Mass Spectrometry of Bio macromolecules, University of Amsterdam, Amsterdam, The Netherlands
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Sun J, Moore L, Xue W, Kim J, Zborowski M, Chalmers JJ. Correlation of simulation/finite element analysis to the separation of intrinsically magnetic spores and red blood cells using a microfluidic magnetic deposition system. Biotechnol Bioeng 2018; 115:1288-1300. [PMID: 29337367 PMCID: PMC6338348 DOI: 10.1002/bit.26550] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Revised: 11/11/2017] [Accepted: 01/09/2018] [Indexed: 01/08/2023]
Abstract
Magnetic separation of cells has been, and continues to be, widely used in a variety of applications, ranging from healthcare diagnostics to detection of food contamination. Typically, these technologies require cells labeled with antibody magnetic particle conjugate and a high magnetic energy gradient created in the flow containing the labeled cells (i.e., a column packed with magnetically inducible material), or dense packing of magnetic particles next to the flow cell. Such designs, while creating high magnetic energy gradients, are not amenable to easy, highly detailed, mathematic characterization. Our laboratories have been characterizing and developing analysis and separation technology that can be used on intrinsically magnetic cells or spores which are typically orders of magnitude weaker than typically immunomagnetically labeled cells. One such separation system is magnetic deposition microscopy (MDM) which not only separates cells, but deposits them in specific locations on slides for further microscopic analysis. In this study, the MDM system has been further characterized, using finite element and computational fluid mechanics software, and separation performance predicted, using a model which combines: 1) the distribution of the intrinsic magnetophoretic mobility of the cells (spores); 2) the fluid flow within the separation device; and 3) accurate maps of the values of the magnetic field (max 2.27 T), and magnetic energy gradient (max of 4.41 T2 /mm) within the system. Guided by this model, experimental studies indicated that greater than 95% of the intrinsically magnetic Bacillus spores can be separated with the MDM system. Further, this model allows analysis of cell trajectories which can assist in the design of higher throughput systems.
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Affiliation(s)
- Jianxin Sun
- William G. Lowrie Department of Chemical and Biomolecular Engineering Director, Analytical Cytometry Shared Resource, The OSU Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio
| | - Lee Moore
- Department of Biomedical Engineering Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio
| | - Wei Xue
- William G. Lowrie Department of Chemical and Biomolecular Engineering Director, Analytical Cytometry Shared Resource, The OSU Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio
| | - James Kim
- William G. Lowrie Department of Chemical and Biomolecular Engineering Director, Analytical Cytometry Shared Resource, The OSU Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio
| | - Maciej Zborowski
- Department of Biomedical Engineering Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio
| | - Jeffrey J Chalmers
- William G. Lowrie Department of Chemical and Biomolecular Engineering Director, Analytical Cytometry Shared Resource, The OSU Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio
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den Besten HM, Wells-Bennik MH, Zwietering MH. Natural Diversity in Heat Resistance of Bacteria and Bacterial Spores: Impact on Food Safety and Quality. Annu Rev Food Sci Technol 2018; 9:383-410. [DOI: 10.1146/annurev-food-030117-012808] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Heidy M.W. den Besten
- Laboratory of Food Microbiology, Wageningen University, 6700 AA Wageningen, The Netherlands
- Top Institute Food and Nutrition, 6709 PA, Wageningen, The Netherlands
| | - Marjon H.J. Wells-Bennik
- NIZO Food Research B.V., 6718 ZB, Ede, The Netherlands
- Top Institute Food and Nutrition, 6709 PA, Wageningen, The Netherlands
| | - Marcel H. Zwietering
- Laboratory of Food Microbiology, Wageningen University, 6700 AA Wageningen, The Netherlands
- Top Institute Food and Nutrition, 6709 PA, Wageningen, The Netherlands
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Gold nanoparticle-based colorimetric sensing of dipicolinic acid from complex samples. Anal Bioanal Chem 2018; 410:1805-1815. [DOI: 10.1007/s00216-017-0836-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2017] [Revised: 11/24/2017] [Accepted: 12/15/2017] [Indexed: 12/29/2022]
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Hsu SK, Chang ZJ, Chang SM. Fluorescent Determination of Copper(II) in Industrial Wastewater Using Thiol-Capped Cadmium Sulfide–Zinc Sulfide Quantum Dots as the Probe. ANAL LETT 2017. [DOI: 10.1080/00032719.2017.1338715] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Shu-Kang Hsu
- Institute of Environmental Engineering, National Chiao Tung University, Hsinchu, Taiwan
| | - Zhao-Jun Chang
- Material and Chemical Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan
| | - Sue-Min Chang
- Institute of Environmental Engineering, National Chiao Tung University, Hsinchu, Taiwan
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Clauwers C, Lood C, Van den Bergh B, van Noort V, Michiels CW. Canonical germinant receptor is dispensable for spore germination in Clostridium botulinum group II strain NCTC 11219. Sci Rep 2017; 7:15426. [PMID: 29133849 PMCID: PMC5684421 DOI: 10.1038/s41598-017-15839-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Accepted: 11/03/2017] [Indexed: 02/07/2023] Open
Abstract
Clostridium botulinum is an anaerobic sporeforming bacterium that is notorious for producing a potent neurotoxin. Spores of C. botulinum can survive mild food processing treatments and subsequently germinate, multiply, produce toxin and cause botulism. Control of spore germination and outgrowth is therefore essential for the safety of mildly processed foods. However, little is known about the process of spore germination in group II C. botulinum (gIICb), which are a major concern in chilled foods because they are psychrotrophic. The classical model of spore germination states that germination is triggered by the binding of a germinant molecule to a cognate germinant receptor. Remarkably, unlike many other sporeformers, gIICb has only one predicted canonical germinant receptor although it responds to multiple germinants. Therefore, we deleted the gerBAC locus that encodes this germinant receptor to determine its role in germination. Surprisingly, the deletion did not affect germination by any of the nutrient germinants, nor by the non-nutrient dodecylamine. We conclude that one or more other, so far unidentified, germinant receptors must be responsible for nutrient induced germination in gIICb. Furthermore, the gerBAC locus was strongly conserved with intact open reading frames in 159 gIICb genomes, suggesting that it has nevertheless an important function.
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Affiliation(s)
- Charlien Clauwers
- Laboratory of Food Microbiology and Leuven Food Science and Nutrition Research Centre (LFoRCe), KU Leuven, Leuven, Belgium
| | - Cédric Lood
- Centre of Microbial and Plant Genetics, KU Leuven, Leuven, Belgium
| | | | - Vera van Noort
- Centre of Microbial and Plant Genetics, KU Leuven, Leuven, Belgium
| | - Chris W Michiels
- Laboratory of Food Microbiology and Leuven Food Science and Nutrition Research Centre (LFoRCe), KU Leuven, Leuven, Belgium.
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Rozali SNM, Milani EA, Deed RC, Silva FVM. Bacteria, mould and yeast spore inactivation studies by scanning electron microscope observations. Int J Food Microbiol 2017; 263:17-25. [PMID: 29024903 DOI: 10.1016/j.ijfoodmicro.2017.10.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 09/07/2017] [Accepted: 10/03/2017] [Indexed: 11/18/2022]
Abstract
Spores are the most resistant form of microbial cells, thus difficult to inactivate. The pathogenic or food spoilage effects of certain spore-forming microorganisms have been the primary basis of sterilization and pasteurization processes. Thermal sterilization is the most common method to inactivate spores present on medical equipment and foods. High pressure processing (HPP) is an emerging and commercial non-thermal food pasteurization technique. Although previous studies demonstrated the effectiveness of thermal and non-thermal spore inactivation, the in-depth mechanisms of spore inactivation are as yet unclear. Live and dead forms of two food spoilage bacteria, a mould and a yeast were examined using scanning electron microscopy before and after the inactivation treatment. Alicyclobacillus acidoterrestris and Geobacillus stearothermophilus bacteria are indicators of acidic foods pasteurization and sterilization processes, respectively. Neosartorya fischeri is a phyto-pathogenic mould attacking fruits. Saccharomyces cerevisiae is a yeast with various applications for winemaking, brewing, baking and the production of biofuel from crops (e.g. sugar cane). Spores of the four microbial species were thermally inactivated. Spores of S. cerevisiae were observed in the ascus and free form after thermal and HPP treatments. Different forms of damage and cell destruction were observed for each microbial spore. Thermal treatment inactivated bacterial spores of A. acidoterrestris and G. stearothermophilus by attacking the inner core of the spore. The heat first altered the membrane permeability allowing the release of intracellular components. Subsequently, hydration of spores, physicochemical modifications of proteins, flattening and formation of indentations occurred, with subsequent spore death. Regarding N. fischeri, thermal inactivation caused cell destruction and leakage of intracellular components. Both thermal and HPP treatments of S. cerevisiae free spores attacked the inner membrane, altering its permeability, and allowing in final stages the transfer of intracellular components to the outside. The spore destruction caused by thermal treatment was more severe than HPP, as HPP had less effect on the spore core. All injured spores have undergone irreversible volume and shape changes. While some of the leakage of spore contents is visible around the deformed but fully shaped spore, other spores exhibited large indentations and were completely deformed, apparently without any contents inside. This current study contributed to the understanding of spore inactivation by thermal and non-thermal processes.
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Affiliation(s)
- Siti N M Rozali
- Chemical and Materials Engineering Department, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Elham A Milani
- Chemical and Materials Engineering Department, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Rebecca C Deed
- School of Biological Sciences, School of Chemical Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Filipa V M Silva
- Chemical and Materials Engineering Department, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand.
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Two complementary approaches to quantify variability in heat resistance of spores of Bacillus subtilis. Int J Food Microbiol 2017; 253:48-53. [DOI: 10.1016/j.ijfoodmicro.2017.04.014] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 03/10/2017] [Accepted: 04/23/2017] [Indexed: 11/20/2022]
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Trunet C, Carlin F, Coroller L. Investigating germination and outgrowth of bacterial spores at several scales. Trends Food Sci Technol 2017. [DOI: 10.1016/j.tifs.2017.03.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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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: 17] [Impact Index Per Article: 2.4] [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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Volpi M, Lomstein BA, Sichert A, Røy H, Jørgensen BB, Kjeldsen KU. Identity, Abundance, and Reactivation Kinetics of Thermophilic Fermentative Endospores in Cold Marine Sediment and Seawater. Front Microbiol 2017; 8:131. [PMID: 28220111 PMCID: PMC5292427 DOI: 10.3389/fmicb.2017.00131] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Accepted: 01/18/2017] [Indexed: 11/23/2022] Open
Abstract
Cold marine sediments harbor endospores of fermentative and sulfate-reducing, thermophilic bacteria. These dormant populations of endospores are believed to accumulate in the seabed via passive dispersal by ocean currents followed by sedimentation from the water column. However, the magnitude of this process is poorly understood because the endospores present in seawater were so far not identified, and only the abundance of thermophilic sulfate-reducing endospores in the seabed has been quantified. We investigated the distribution of thermophilic fermentative endospores (TFEs) in water column and sediment of Aarhus Bay, Denmark, to test the role of suspended dispersal and determine the rate of endospore deposition and the endospore abundance in the sediment. We furthermore aimed to determine the time course of reactivation of the germinating TFEs. TFEs were induced to germinate and grow by incubating pasteurized sediment and water samples anaerobically at 50°C. We observed a sudden release of the endospore component dipicolinic acid immediately upon incubation suggesting fast endospore reactivation in response to heating. Volatile fatty acids (VFAs) and H2 began to accumulate exponentially after 3.5 h of incubation showing that reactivation was followed by a short phase of outgrowth before germinated cells began to divide. Thermophilic fermenters were mainly present in the sediment as endospores because the rate of VFA accumulation was identical in pasteurized and non-pasteurized samples. Germinating TFEs were identified taxonomically by reverse transcription, PCR amplification and sequencing of 16S rRNA. The water column and sediment shared the same phylotypes, thereby confirming the potential for seawater dispersal. The abundance of TFEs was estimated by most probable number enumeration, rates of VFA production, and released amounts of dipicolinic acid during germination. The surface sediment contained ∼105-106 inducible TFEs cm-3. TFEs thus outnumber thermophilic sulfate-reducing endospores by an order of magnitude. The abundance of cultivable TFEs decreased exponentially with sediment depth with a half-life of 350 years. We estimate that 6 × 109 anaerobic thermophilic endospores are deposited on the seafloor per m2 per year in Aarhus Bay, and that these thermophiles represent >10% of the total endospore community in the surface sediment.
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Affiliation(s)
- Marta Volpi
- Center for Geomicrobiology, Department of Bioscience, Aarhus UniversityAarhus, Denmark
| | | | | | | | | | - Kasper U. Kjeldsen
- Center for Geomicrobiology, Department of Bioscience, Aarhus UniversityAarhus, Denmark
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Antibacterial Properties of Visible-Light-Responsive Carbon-Containing Titanium Dioxide Photocatalytic Nanoparticles against Anthrax. NANOMATERIALS 2016; 6:nano6120237. [PMID: 28335365 PMCID: PMC5302719 DOI: 10.3390/nano6120237] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 11/28/2016] [Accepted: 12/06/2016] [Indexed: 01/12/2023]
Abstract
The bactericidal activity of conventional titanium dioxide (TiO2) photocatalyst is effective only on irradiation by ultraviolet light, which restricts the applications of TiO2 for use in living environments. Recently, carbon-containing TiO2 nanoparticles [TiO2(C) NP] were found to be a visible-light-responsive photocatalyst (VLRP), which displayed significantly enhanced antibacterial properties under visible light illumination. However, whether TiO2(C) NPs exert antibacterial properties against Bacillus anthracis remains elusive. Here, we evaluated these VLRP NPs in the reduction of anthrax-induced pathogenesis. Bacteria-killing experiments indicated that a significantly higher proportion (40%–60%) of all tested Bacillus species, including B. subtilis, B. cereus, B. thuringiensis, and B. anthracis, were considerably eliminated by TiO2(C) NPs. Toxin inactivation analysis further suggested that the TiO2(C) NPs efficiently detoxify approximately 90% of tested anthrax lethal toxin, a major virulence factor of anthrax. Notably, macrophage clearance experiments further suggested that, even under suboptimal conditions without considerable bacterial killing, the TiO2(C) NP-mediated photocatalysis still exhibited antibacterial properties through the reduction of bacterial resistance against macrophage killing. Our results collectively suggested that TiO2(C) NP is a conceptually feasible anti-anthrax material, and the relevant technologies described herein may be useful in the development of new strategies against anthrax.
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50
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Berendsen EM, Koning RA, Boekhorst J, de Jong A, Kuipers OP, Wells-Bennik MHJ. High-Level Heat Resistance of Spores of Bacillus amyloliquefaciens and Bacillus licheniformis Results from the Presence of a spoVA Operon in a Tn 1546 Transposon. Front Microbiol 2016; 7:1912. [PMID: 27994575 PMCID: PMC5133452 DOI: 10.3389/fmicb.2016.01912] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 11/15/2016] [Indexed: 11/19/2022] Open
Abstract
Bacterial endospore formers can produce spores that are resistant to many food processing conditions, including heat. Some spores may survive heating processes aimed at production of commercially sterile foods. Recently, it was shown that a spoVA operon, designated spoVA2mob, present on a Tn1546 transposon in Bacillus subtilis, leads to profoundly increased wet heat resistance of B. subtilis spores. Such Tn1546 transposon elements including the spoVA2mob operon were also found in several strains of Bacillus amyloliquefaciens and Bacillus licheniformis, and these strains were shown to produce spores with significantly higher resistances to wet heat than their counterparts lacking this transposon. In this study, the locations and compositions of Tn1546 transposons encompassing the spoVA2mob operons in B. amyloliquefaciens and B. licheniformis were analyzed. Introduction of these spoVA2mob operons into B. subtilis 168 (producing spores that are not highly heat resistant) rendered mutant 168 strains that produced high-level heat resistant spores, demonstrating that these elements in B. amyloliquefaciens and B. licheniformis are responsible for high level heat resistance of spores. Assessment of growth of the nine strains of each species between 5.2°C and 57.7°C showed some differences between strains, especially at lower temperatures, but all strains were able to grow at 57.7°C. Strains of B. amyloliquefaciens and B. licheniformis that contain the Tn1546 elements (and produce high-level heat resistant spores) grew at temperatures similar to those of their Tn1546-negative counterparts that produce low-level heat resistant spores. The findings presented in this study allow for detection of B. amyloliquefaciens and B. licheniformis strains that produce highly heat resistant spores in the food chain.
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Affiliation(s)
- Erwin M Berendsen
- Top Institute Food and NutritionWageningen, Netherlands; Laboratory of Molecular Genetics, University of GroningenGroningen, Netherlands; NIZO Food ResearchEde, Netherlands
| | - Rosella A Koning
- Top Institute Food and NutritionWageningen, Netherlands; NIZO Food ResearchEde, Netherlands
| | - Jos Boekhorst
- Top Institute Food and NutritionWageningen, Netherlands; NIZO Food ResearchEde, Netherlands
| | - Anne de Jong
- Top Institute Food and NutritionWageningen, Netherlands; Laboratory of Molecular Genetics, University of GroningenGroningen, Netherlands
| | - Oscar P Kuipers
- Top Institute Food and NutritionWageningen, Netherlands; Laboratory of Molecular Genetics, University of GroningenGroningen, Netherlands
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