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Jenull S, Bauer T, Silbermayr K, Dreer M, Stark TD, Ehling-Schulz M. The toxicological spectrum of the Bacillus cereus toxin cereulide points towards niche-specific specialisation. Environ Microbiol 2023; 25:2231-2249. [PMID: 37354053 DOI: 10.1111/1462-2920.16454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 06/06/2023] [Indexed: 06/26/2023]
Abstract
Most microbes share their environmental niches with very different forms of life thereby engaging in specialised relationships to enable their persistence. The bacterium Bacillus cereus occurs ubiquitously in the environment with certain strain backgrounds causing foodborne and opportunistic infections in humans. The emetic lineage of B. cereus is capable of producing the toxin cereulide, which evokes emetic illnesses. Although food products favouring the accumulation of cereulide are known, the ecological role of cereulide and the environmental niche of emetic B. cereus remain elusive. To better understand the ecology of cereulide-producing B. cereus, we systematically assayed the toxicological spectrum of cereulide on a variety of organisms belonging to different kingdoms. As cereulide is a potassium ionophore, we further tested the effect of environmental potassium levels on the action of cereulide. We found that adverse effects of cereulide exposure are species-specific, which can be exacerbated with increased environmental potassium. Additionally, we demonstrate that cereulide is produced within an insect cadaver indicating its potential ecological function for a saprophytic lifestyle. Collectively, distinct cereulide susceptibilities of other organisms may reflect its role in enabling competitive niche specialization of emetic B. cereus.
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Affiliation(s)
- Sabrina Jenull
- Institute of Microbiology, Department of Pathobiology, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Tobias Bauer
- Institute of Microbiology, Department of Pathobiology, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Katja Silbermayr
- Institute of Parasitology, Department of Pathobiology, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Maximilian Dreer
- Department of Functional and Evolutionary Ecology, Archaea Biology and Ecogenomics Unit, University of Vienna, Vienna, Austria
| | - Timo D Stark
- Food Chemistry and Molecular Sensory Science, Technical University of Munich, Freising, Germany
| | - Monika Ehling-Schulz
- Institute of Microbiology, Department of Pathobiology, University of Veterinary Medicine Vienna, Vienna, Austria
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2
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Al-Theyab N, Alrasheed O, Abuelizz HA, Liang M. Draft genome sequence of potato crop bacterial isolates and nanoparticles-intervention for the induction of secondary metabolites biosynthesis. Saudi Pharm J 2023; 31:783-794. [PMID: 37228327 PMCID: PMC10203779 DOI: 10.1016/j.jsps.2023.04.016] [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: 02/27/2023] [Accepted: 04/17/2023] [Indexed: 05/27/2023] Open
Abstract
Introduction Insights about the effects of gold nanoparticles (AuNPs) on the biosynthetic manipulation of unknown microbe secondary metabolites could be a promising technique for prospective research on nano-biotechnology. Aim In this research, we aimed to isolate a fresh, non-domesticated unknown bacterium strain from a common scab of potato crop located in Saudi Arabia and study the metabolic profile. Methodology This was achieved through genomic DNA (gDNA) sequencing using Oxford Nanopore Technology. The genomic data were subjected to several bioinformatics tools, including canu-1.9 software, Prokka, DFAST, Geneious Prime, and AntiSMASH. We exposed the culture of the bacterial isolate with different concentrations of AuNPs and investigated the effects of AuNPs on secondary metabolites biosynthesis using several analytical techniques. Furthermore, Tandem-mass spectrometric (MS/MS) technique was optimized for the characterization of several significant sub-classes. Results The genomic draft sequence assembly, alignment, and annotation have verified the bacterial isolate as Priestia megaterium. This bacterium has secondary metabolites related to different biosynthetic gene clusters. AuNPs intervention showed an increase in the production of compounds with the molecular weights of 254 and 270 Da in a direct-dependent manner with the increase of the AuNPs concentrations. Conclusion The increase in the yields of compound 1 and 2 concomitantly with the increase in the concentration of the added AuNPs provide evidences about the effects of nanoparticles on the biosynthesis of the secondary metabolites. It contributes to the discovery of genes involved in different biosynthetic gene clusters (BGCs) and prediction of the structures of the natural products.
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Affiliation(s)
- Nada Al-Theyab
- School of Biomedical Science and Pharmacy, University of Newcastle, Callaghan, New South Wales, Australia
- Department of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia
| | - Omar Alrasheed
- Department of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia
| | - Hatem A. Abuelizz
- Department of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia
| | - Mingtao Liang
- School of Biomedical Science and Pharmacy, University of Newcastle, Callaghan, New South Wales, Australia
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3
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Dhungel L, Bonner R, Cook M, Henson D, Moulder T, Benbow ME, Jordan H. Impact of Temperature and Oxygen Availability on Gene Expression Patterns of Mycobacterium ulcerans. Microbiol Spectr 2023; 11:e0496822. [PMID: 36912651 PMCID: PMC10100886 DOI: 10.1128/spectrum.04968-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Accepted: 01/29/2023] [Indexed: 03/14/2023] Open
Abstract
Buruli ulcer disease is a neglected tropical disease caused by the environmental pathogen Mycobacterium ulcerans. The M. ulcerans major virulence factor is mycolactone, a lipid cytotoxic compound whose genes are carried on a plasmid. Although an exact reservoir and mode(s) of transmission are unknown, data provide evidence of both. First, Buruli ulcer incidence and M. ulcerans presence have been linked to slow-moving water with low oxygen. M. ulcerans has also been suggested to be sensitive to UV due to termination in crtI, encoding a phytoene dehydrogenase, required for carotenoid production. Further, M. ulcerans has been shown to cause disease following puncture but not when introduced to open abrasion sites, suggesting that puncture is necessary for transmission and pathology. Despite these findings, the function and modulation of mycolactone and other genes in response to dynamic abiotic conditions such as UV, temperature, and oxygen have not been shown. In this study, we investigated modulation of mycolactone and other genes on exposure to changing UV and oxygen microenvironmental conditions. Mycolactone expression was downregulated on exposure to the single stress high temperature and did not change significantly with exposure to UV; however, it was upregulated when exposed to microaerophilic conditions. Mycolactone expression was downregulated under combined stresses of high temperature and low oxygen, but there was upregulation of several stress response genes. Taken together, results suggest that temperature shapes M. ulcerans metabolic response more so than UV exposure or oxygen requirements. These data help to define the environmental niche of M. ulcerans and metabolic responses during initial human infection. IMPORTANCE Buruli ulcer is a debilitating skin disease caused by the environmental pathogen Mycobacterium ulcerans. M. ulcerans produces a toxic compound, mycolactone, which leads to tissue necrosis and ulceration. Barriers to preventing Buruli ulcer include an incomplete understanding of M. ulcerans reservoirs, how the pathogen is transmitted, and under what circumstances mycolactone and other M. ulcerans genes are expressed and produced in its natural environment and in the host. We conducted a study to investigate M. ulcerans gene expression under several individual or combined abiotic conditions. Our data showed that mycolactone expression was downregulated under combined stresses of high temperature and low oxygen but there was upregulation of several stress response genes. These data are among only a few studies measuring modulation of mycolactone and other M. ulcerans genes that could be involved in pathogen fitness in its natural environment and virulence while within the host.
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Affiliation(s)
- Laxmi Dhungel
- Department of Biological Sciences, Mississippi State University, Mississippi State, Mississippi, USA
| | - Raisa Bonner
- Department of Biological Sciences, Mississippi State University, Mississippi State, Mississippi, USA
| | - Meagan Cook
- Department of Biological Sciences, Mississippi State University, Mississippi State, Mississippi, USA
| | - Duncan Henson
- Department of Biological Sciences, Mississippi State University, Mississippi State, Mississippi, USA
| | - Trent Moulder
- Department of Biological Sciences, Mississippi State University, Mississippi State, Mississippi, USA
| | - M. Eric Benbow
- Department of Entomology, Michigan State University, East Lansing, Michigan, USA
- Ecology, Evolution and Behavior Program, Michigan State University, East Lansing, Michigan, USA
- AgBioResearch, Michigan State University, East Lansing, Michigan, USA
- Department of Osteopathic Medical Specialties, Michigan State University, East Lansing, Michigan, USA
| | - Heather Jordan
- Department of Biological Sciences, Mississippi State University, Mississippi State, Mississippi, USA
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4
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Yang S, Wang Y, Liu Y, Jia K, Zhang Z, Dong Q. Cereulide and Emetic Bacillus cereus: Characterizations, Impacts and Public Precautions. Foods 2023; 12:833. [PMID: 36832907 PMCID: PMC9956921 DOI: 10.3390/foods12040833] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 02/10/2023] [Accepted: 02/12/2023] [Indexed: 02/18/2023] Open
Abstract
Cereulide, which can be produced by Bacillus cereus, is strongly associated with emetic-type food poisoning outbreaks. It is an extremely stable emetic toxin, which is unlikely to be inactivated by food processing. Considering the high toxicity of cereulide, its related hazards raise public concerns. A better understanding of the impact of B. cereus and cereulide is urgently needed to prevent contamination and toxin production, thereby protecting public health. Over the last decade, a wide range of research has been conducted regarding B. cereus and cereulide. Despite this, summarized information highlighting precautions at the public level involving the food industry, consumers and regulators is lacking. Therefore, the aim of the current review is to summarize the available data describing the characterizations and impacts of emetic B. cereus and cereulide; based on this information, precautions at the public level are proposed.
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Affiliation(s)
| | | | | | | | | | - Qingli Dong
- School of Health Science and Engineering, University of Shanghai for Science and Technology, Jungong Road No. 334, Yangpu District, Shanghai 200093, China
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5
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Intraspecific Diversity and Pathogenicity of Bacillus thuringiensis Isolates from an Emetic Illness. Toxins (Basel) 2023; 15:toxins15020089. [PMID: 36828404 PMCID: PMC9963800 DOI: 10.3390/toxins15020089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 01/10/2023] [Accepted: 01/12/2023] [Indexed: 01/21/2023] Open
Abstract
This study describes an emetic food-borne intoxication associated with a Bacillus cereus group species and the characterization of the bacterial isolates from the incident in aspects of molecular tying, genetic factors, cytotoxicity, and pathogenic mechanisms relating to emetic illness. Through the polyphasic identification approach, all seven isolates obtained from food and clinical samples were identified as Bacillus thuringiensis. According to multilocus sequence typing (MLST) analysis, intraspecific diversity was found within the B. thuringiensis isolates. Four allelic profiles were found, including two previously known STs (ST8 and ST15) and two new STs (ST2804 and ST2805). All isolates harbored gene fragments located in the cereulide synthetase (ces) gene cluster. The heat-treated culture supernatants of three emetic B. thuringiensis isolates, FC2, FC7, and FC8, caused vacuolation and exhibited toxicity to Caco-2 cells, with CC50 values of 56.57, 72.17, and 79.94 µg/mL, respectively. The flow cytometry with the Annexin V/PI assay revealed both apoptosis and necrosis mechanisms, but necrosis was the prominent mechanism that caused Caco-2 cell destruction by FC2, the most toxic isolate.
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6
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Lin Y, Briandet R, Kovács ÁT. Bacillus cereus sensu lato biofilm formation and its ecological importance. Biofilm 2022; 4:100070. [PMID: 35243332 PMCID: PMC8861577 DOI: 10.1016/j.bioflm.2022.100070] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 02/04/2022] [Accepted: 02/05/2022] [Indexed: 12/20/2022] Open
Abstract
Biofilm formation is a ubiquitous process of bacterial communities that enables them to survive and persist in various environmental niches. The Bacillus cereus group includes phenotypically diversified species that are widely distributed in the environment. Often, B. cereus is considered a soil inhabitant, but it is also commonly isolated from plant roots, nematodes, and food products. Biofilms differ in their architecture and developmental processes, reflecting adaptations to specific niches. Importantly, some B. cereus strains are foodborne pathogens responsible for two types of gastrointestinal diseases, diarrhea and emesis, caused by distinct toxins. Thus, the persistency of biofilms is of particular concern for the food industry, and understanding the underlying mechanisms of biofilm formation contributes to cleaning procedures. This review focuses on the genetic background underpinning the regulation of biofilm development, as well as the matrix components associated with biofilms. We also reflect on the correlation between biofilm formation and the development of highly resistant spores. Finally, advances in our understanding of the ecological importance and evolution of biofilm formation in the B. cereus group are discussed.
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Affiliation(s)
- Yicen Lin
- Bacterial Interactions and Evolution Group, DTU Bioengineering, Technical University of Denmark, 2800, Lyngby, Denmark
| | - Romain Briandet
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, 78350, Jouy-en-Josas, France
| | - Ákos T. Kovács
- Bacterial Interactions and Evolution Group, DTU Bioengineering, Technical University of Denmark, 2800, Lyngby, Denmark
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7
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Wong JX, Ramli S, Desa S, Chen SN. Use of Centella asiatica extract in reducing microbial contamination and browning effect in fresh cut fruits and vegetables during storage: A potential alternative of synthetic preservatives. Lebensm Wiss Technol 2021. [DOI: 10.1016/j.lwt.2021.112229] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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8
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Lin Y, Alstrup M, Pang JKY, Maróti G, Er-Rafik M, Tourasse N, Økstad OA, Kovács ÁT. Adaptation of Bacillus thuringiensis to Plant Colonization Affects Differentiation and Toxicity. mSystems 2021; 6:e0086421. [PMID: 34636664 PMCID: PMC8510532 DOI: 10.1128/msystems.00864-21] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 09/27/2021] [Indexed: 01/11/2023] Open
Abstract
The Bacillus cereus group (Bacillus cereus sensu lato) has a diverse ecology, including various species that are vertebrate or invertebrate pathogens. Few isolates from the B. cereus group have however been demonstrated to benefit plant growth. Therefore, it is crucial to explore how bacterial development and pathogenesis evolve during plant colonization. Herein, we investigated Bacillus thuringiensis (Cry-) adaptation to the colonization of Arabidopsis thaliana roots and monitored changes in cellular differentiation in experimentally evolved isolates. Isolates from two populations displayed improved iterative ecesis on roots and increased virulence against insect larvae. Molecular dissection and recreation of a causative mutation revealed the importance of a nonsense mutation in the rho transcription terminator gene. Transcriptome analysis revealed how Rho impacts various B. thuringiensis genes involved in carbohydrate metabolism and virulence. Our work suggests that evolved multicellular aggregates have a fitness advantage over single cells when colonizing plants, creating a trade-off between swimming and multicellularity in evolved lineages, in addition to unrelated alterations in pathogenicity. IMPORTANCE Biologicals-based plant protection relies on the use of safe microbial strains. During application of biologicals to the rhizosphere, microbes adapt to the niche, including genetic mutations shaping the physiology of the cells. Here, the experimental evolution of Bacillus thuringiensis lacking the insecticide crystal toxins was examined on the plant root to reveal how adaptation shapes the differentiation of this bacterium. Interestingly, evolution of certain lineages led to increased hemolysis and insect larva pathogenesis in B. thuringiensis driven by transcriptional rewiring. Further, our detailed study reveals how inactivation of the transcription termination protein Rho promotes aggregation on the plant root in addition to altered differentiation and pathogenesis in B. thuringiensis.
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Affiliation(s)
- Yicen Lin
- Bacterial Interactions and Evolution Group, DTU Bioengineering, Technical University of Denmark, Lyngby, Denmark
| | - Monica Alstrup
- Bacterial Interactions and Evolution Group, DTU Bioengineering, Technical University of Denmark, Lyngby, Denmark
| | - Janet Ka Yan Pang
- Bacterial Interactions and Evolution Group, DTU Bioengineering, Technical University of Denmark, Lyngby, Denmark
| | - Gergely Maróti
- Institute of Plant Biology, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary
| | - Mériem Er-Rafik
- National Centre for Nano Fabrication and Characterization, Technical University of Denmark, Lyngby, Denmark
| | - Nicolas Tourasse
- Université Bordeaux, CNRS, INSERM, ARNA, UMR 5320, U1212, Bordeaux, France
| | - Ole Andreas Økstad
- Centre for Integrative Microbial Evolution, University of Oslo, Oslo, Norway
- Section for Pharmacology and Pharmaceutical Biosciences, Department of Pharmacy, University of Oslo, Oslo, Norway
| | - Ákos T. Kovács
- Bacterial Interactions and Evolution Group, DTU Bioengineering, Technical University of Denmark, Lyngby, Denmark
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9
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Cereulide Exposure Caused Cytopathogenic Damages of Liver and Kidney in Mice. Int J Mol Sci 2021; 22:ijms22179148. [PMID: 34502057 PMCID: PMC8431326 DOI: 10.3390/ijms22179148] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2021] [Revised: 08/20/2021] [Accepted: 08/20/2021] [Indexed: 12/18/2022] Open
Abstract
Cereulide is one of the main food-borne toxins for vomiting synthesized by Bacillus cereus, and it widely contaminates meat, eggs, milk, and starchy foods. However, the toxicological effects and mechanisms of the long-time exposure of cereulide in vivo remain unknown. In this study, oral administration of 50 and 200 μg/kg body weight cereulide in the mice for 28 days caused oxidative stress in liver and kidney tissues and induce abnormal expression of inflammatory factors. In pathogenesis, cereulide exposure activated endoplasmic reticulum stress (ER stress) via the pathways of inositol-requiring enzyme 1α (IRE1α)/Xbox binding protein (XBP1) and PRKR-like ER kinase (PERK)/eukaryotic translation initiation factor 2α (eIF2α), and consequently led to the apoptosis and tissue damages in mouse liver and kidney. In vitro, we confirmed that the accumulation of reactive oxygen species (ROS) caused by cereulide is the main factor leading to ER stress in HepaRG and HEK293T cells. Supplementation of sodium butyrate (NaB) inhibited the activations of IRE1α/XBP1 and PERK/eIF2α pathways caused by cereulide exposure in mice, and reduced the cell apoptosis in liver and kidney. In conclusion, this study provides a new insight in understanding the toxicological mechanism and prevention of cereulide exposure.
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10
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Jovanovic J, Ornelis VFM, Madder A, Rajkovic A. Bacillus cereus food intoxication and toxicoinfection. Compr Rev Food Sci Food Saf 2021; 20:3719-3761. [PMID: 34160120 DOI: 10.1111/1541-4337.12785] [Citation(s) in RCA: 55] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 05/13/2021] [Accepted: 05/15/2021] [Indexed: 12/12/2022]
Abstract
Bacillus cereus is one of the leading etiological agents of toxin-induced foodborne diseases. Its omnipresence in different environments, spore formation, and its ability to adapt to varying conditions and produce harmful toxins make this pathogen a health hazard that should not be underestimated. Food poisoning by B. cereus can manifest itself as an emetic or diarrheal syndrome. The former is caused by the release of the potent peptide toxin cereulide, whereas the latter is the result of proteinaceous enterotoxins (e.g., hemolysin BL, nonhemolytic enterotoxin, and cytotoxin K). The final harmful effect is not only toxin and strain dependent, but is also affected by the stress responses, accessory virulence factors, and phenotypic properties under extrinsic, intrinsic, and explicit food conditions and host-related environment. Infamous portrait of B. cereus as a foodborne pathogen, as well as a causative agent of nongastrointestinal infections and even nosocomial complications, has inspired vast volumes of multidisciplinary research in food and clinical domains. As a result, extensive original data became available asking for a new, both broad and deep, multifaceted look into the current state-of-the art regarding the role of B. cereus in food safety. In this review, we first provide an overview of the latest knowledge on B. cereus toxins and accessory virulence factors. Second, we describe the novel taxonomy and some of the most pertinent phenotypic characteristics of B. cereus related to food safety. We link these aspects to toxin production, overall pathogenesis, and interactions with its human host. Then we reflect on the prevalence of different toxinotypes in foods opening the scene for epidemiological aspects of B. cereus foodborne diseases and methods available to prevent food poisoning including overview of the different available methods to detect B. cereus and its toxins.
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Affiliation(s)
- Jelena Jovanovic
- Department of Food Technology, Safety and Health, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
| | - Vincent F M Ornelis
- Department of Organic and Macromolecular Chemistry, Faculty of Sciences, Ghent University, Ghent, Belgium
| | - Annemieke Madder
- Department of Organic and Macromolecular Chemistry, Faculty of Sciences, Ghent University, Ghent, Belgium
| | - Andreja Rajkovic
- Department of Food Technology, Safety and Health, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
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11
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Zhao Y, Jiang S, Zhang J, Guan XL, Sun BG, Sun L. A virulent Bacillus cereus strain from deep-sea cold seep induces pyroptosis in a manner that involves NLRP3 inflammasome, JNK pathway, and lysosomal rupture. Virulence 2021; 12:1362-1376. [PMID: 34009097 PMCID: PMC8143241 DOI: 10.1080/21505594.2021.1926649] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Recent studies indicate that the Bacillus species is distributed in deep-sea environments. However, no specific studies on deep-sea Bacillus cereus have been documented. In the present work, we isolated a B. cereus strain, H2, from the deep-sea cold seep in South China Sea. We characterized the pathogenic potential of H2 and investigated H2-induced death of different types of cells. We found that H2 was capable of tissue dissemination and causing acute mortality in mice and fish following intraperitoneal/intramuscular injection. In vitro studies revealed that H2 infection of macrophages induced pyroptosis and activation of the NLRP3 inflammasome pathway that contributed partly to cell death. H2 infection activated p38, JNK, and ERK, but only JNK proved to participate in H2-triggered cell death. Reactive oxygen species (ROS) and intracellular Ca2+ were essential to H2-induced activation of JNK and NLRP3 inflammasome. In contrast, lysosomal rupture and cathepsins were required for H2-induced NLRP3 inflammasome activation but not for JNK activation. This study revealed for the first time the virulence characteristics of deep-sea B. cereus and provided new insights into the mechanism of B. cereus infection.
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Affiliation(s)
- Yan Zhao
- College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, China.,Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, China.,CAS and Shandong Province Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China
| | - Shuai Jiang
- Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, China.,CAS and Shandong Province Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China
| | - Jian Zhang
- Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, China.,CAS and Shandong Province Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China.,Deep Sea Research Center, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China
| | - Xiao-Lu Guan
- Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, China.,CAS and Shandong Province Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China
| | - Bo-Guang Sun
- Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, China.,CAS and Shandong Province Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China
| | - Li Sun
- Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, China.,CAS and Shandong Province Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China
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12
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Jessberger N, Dietrich R, Granum PE, Märtlbauer E. The Bacillus cereus Food Infection as Multifactorial Process. Toxins (Basel) 2020; 12:E701. [PMID: 33167492 PMCID: PMC7694497 DOI: 10.3390/toxins12110701] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 10/30/2020] [Accepted: 11/02/2020] [Indexed: 02/06/2023] Open
Abstract
The ubiquitous soil bacterium Bacillus cereus presents major challenges to food safety. It is responsible for two types of food poisoning, the emetic form due to food intoxication and the diarrheal form emerging from food infections with enteropathogenic strains, also known as toxico-infections, which are the subject of this review. The diarrheal type of food poisoning emerges after production of enterotoxins by viable bacteria in the human intestine. Basically, the manifestation of the disease is, however, the result of a multifactorial process, including B. cereus prevalence and survival in different foods, survival of the stomach passage, spore germination, motility, adhesion, and finally enterotoxin production in the intestine. Moreover, all of these processes are influenced by the consumed foodstuffs as well as the intestinal microbiota which have, therefore, to be considered for a reliable prediction of the hazardous potential of contaminated foods. Current knowledge regarding these single aspects is summarized in this review aiming for risk-oriented diagnostics for enteropathogenic B. cereus.
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Affiliation(s)
- Nadja Jessberger
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Schönleutnerstr. 8, 85764 Oberschleißheim, Germany; (R.D.); (E.M.)
| | - Richard Dietrich
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Schönleutnerstr. 8, 85764 Oberschleißheim, Germany; (R.D.); (E.M.)
| | - Per Einar Granum
- Department of Food Safety and Infection Biology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, P.O. Box 5003 NMBU, 1432 Ås, Norway;
| | - Erwin Märtlbauer
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Schönleutnerstr. 8, 85764 Oberschleißheim, Germany; (R.D.); (E.M.)
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13
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Acosta-Cortés AG, Martinez-Ledezma C, López-Chuken UJ, Kaushik G, Nimesh S, Villarreal-Chiu JF. Polyphosphate recovery by a native Bacillus cereus strain as a direct effect of glyphosate uptake. THE ISME JOURNAL 2019; 13:1497-1505. [PMID: 30742059 PMCID: PMC6776029 DOI: 10.1038/s41396-019-0366-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 01/15/2019] [Accepted: 01/22/2019] [Indexed: 11/18/2022]
Abstract
Seven bacterial strains isolated from a glyphosate-exposed orange plantation site were exposed to 1 mM N-(phosphonomethyl)glycine supplied as a phosphorus source. While some exhibited good biodegradation profiles, the strain 6 P, identified as Bacillus cereus, was the only strain capable of releasing inorganic phosphate to the culture supernatant, while accumulating polyphosphate intracellularly along the experimentation time. The composition and purity of the intracellular polyphosphate accumulated by the strain 6 P were confirmed by FTIR analysis. To date, the biological conversion of glyphosate into polyphosphate has not been reported. However, given the importance of this biopolymer in the survival of microorganisms, it can be expected that this process could represent an important ecological advantage for the adaptation of this strain to an ecological niche exposed to this herbicide. The polyphosphate production yield was calculated as 4 mg l-1, while the glyphosate biodegradation kinetic constant was calculated on 0.003 h-1 using the modified Hockey-Stick first-order kinetic model, with a half-life of 279 h. Our results suggest that B. cereus 6 P is a potential candidate for the generation of an innovative biotechnological process to produce polyphosphate through the biodegradation of the herbicide glyphosate.
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Affiliation(s)
- Alejandra Guadalupe Acosta-Cortés
- Universidad Autónoma de Nuevo León, Facultad de Ciencias Químicas, Laboratorio de Biotecnología. Av, Universidad S/N Ciudad Universitaria, San Nicolás de los Garza, Nuevo León, 66455, Mexico
| | - Cesar Martinez-Ledezma
- Universidad Autónoma de Nuevo León, Facultad de Ciencias Químicas, Laboratorio de Biotecnología. Av, Universidad S/N Ciudad Universitaria, San Nicolás de los Garza, Nuevo León, 66455, Mexico
| | - Ulrico Javier López-Chuken
- Universidad Autónoma de Nuevo León, Facultad de Ciencias Químicas, Laboratorio de Investigación en Ciencias Ambientales. Av, Universidad S/N Ciudad Universitaria, San Nicolás de los Garza, Nuevo León, 66455, Mexico
| | - Garima Kaushik
- Department of Environmental Science. School of Earth Science, Central University of Rajasthan, Ajmer, Rajasthan, 305817, India
| | - Surendra Nimesh
- Department of Biotechnology. School of Life Sciences, Central University of Rajasthan, Ajmer, Rajasthan, 305817, India
| | - Juan Francisco Villarreal-Chiu
- Universidad Autónoma de Nuevo León, Facultad de Ciencias Químicas, Laboratorio de Biotecnología. Av, Universidad S/N Ciudad Universitaria, San Nicolás de los Garza, Nuevo León, 66455, Mexico.
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14
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Ehling-Schulz M, Lereclus D, Koehler TM. The Bacillus cereus Group: Bacillus Species with Pathogenic Potential. Microbiol Spectr 2019; 7:10.1128/microbiolspec.gpp3-0032-2018. [PMID: 31111815 PMCID: PMC6530592 DOI: 10.1128/microbiolspec.gpp3-0032-2018] [Citation(s) in RCA: 235] [Impact Index Per Article: 47.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Indexed: 12/17/2022] Open
Abstract
The Bacillus cereus group includes several Bacillus species with closely related phylogeny. The most well-studied members of the group, B. anthracis, B. cereus, and B. thuringiensis, are known for their pathogenic potential. Here, we present the historical rationale for speciation and discuss shared and unique features of these bacteria. Aspects of cell morphology and physiology, and genome sequence similarity and gene synteny support close evolutionary relationships for these three species. For many strains, distinct differences in virulence factor synthesis provide facile means for species assignment. B. anthracis is the causative agent of anthrax. Some B. cereus strains are commonly recognized as food poisoning agents, but strains can also cause localized wound and eye infections as well as systemic disease. Certain B. thuringiensis strains are entomopathogens and have been commercialized for use as biopesticides, while some strains have been reported to cause infection in immunocompromised individuals. In this article we compare and contrast B. anthracis, B. cereus, and B. thuringiensis, including ecology, cell structure and development, virulence attributes, gene regulation and genetic exchange systems, and experimental models of disease.
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Affiliation(s)
- Monika Ehling-Schulz
- Institute of Microbiology, Department of Pathology, University of Veterinary Medicine, 1210 Vienna, Austria
| | - Didier Lereclus
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France
| | - Theresa M Koehler
- Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center - Houston, Houston, TX 77030
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15
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Tian S, Xiong H, Geng P, Yuan Z, Hu X. CesH Represses Cereulide Synthesis as an Alpha/Beta Fold Hydrolase in Bacillus cereus. Toxins (Basel) 2019; 11:E231. [PMID: 31010094 PMCID: PMC6521208 DOI: 10.3390/toxins11040231] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 04/13/2019] [Accepted: 04/20/2019] [Indexed: 12/18/2022] Open
Abstract
Cereulide is notorious as a heat-stable emetic toxin produced by Bacillus cereus and glucose is supposed to be an ingredient supporting its formation. This study showed that glucose addition benefited on cell growth and the early transcription of genes involved in substrate accumulation and toxin synthesis, but it played a negative role in the final production of cereulide. Meanwhile, a lasting enhancement of cesH transcription was observed with the addition of glucose. Moreover, the cereulide production in ΔcesH was obviously higher than that in the wild type. This indicates that CesH has a repression effect on cereulide production. Bioinformatics analysis revealed that CesH was an alpha/beta hydrolase that probably associated with the cell membrane, which was verified by subcellular localization. The esterase activity against para-nitrophenyl acetate (PNPC2) of the recombinant CesH was confirmed. Although no sign of ester bond cleavage in cereulide or valinomycin was demonstrated in in vitro assays, CesH could reverse the cereulide analogue sensitivity of Bacillus subtilis in vivo, by which toxin degradation was facilitated. Moreover, site directed mutations identified that the conserved catalytic triad of CesH might consist of Serine 86, Glutamate 199, and Histidine 227. These results help us to understand the regulation of cereulide production and provide clues for developing control measurements.
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Affiliation(s)
- Shen Tian
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China.
- University of the Chinese Academy of Sciences, Beijing 100049, China.
| | - Hairong Xiong
- College of Life Science, South-Central University for Nationalities, Wuhan 430074, China.
| | - Peiling Geng
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China.
- University of the Chinese Academy of Sciences, Beijing 100049, China.
| | - Zhiming Yuan
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China.
| | - Xiaomin Hu
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China.
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16
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Ducrest PJ, Pfammatter S, Stephan D, Vogel G, Thibault P, Schnyder B. Rapid detection of Bacillus ionophore cereulide in food products. Sci Rep 2019; 9:5814. [PMID: 30967595 PMCID: PMC6456620 DOI: 10.1038/s41598-019-42167-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 03/22/2019] [Indexed: 12/17/2022] Open
Abstract
Cereulide is a toxic cyclic depsipeptide produced by certain strains of Bacillus cereus found in soil and food products. While some harmless strains of Bacillus are used as probiotic, others can cause nausea and vomiting, and represent an important food safety concern. Current detection methods are time consuming and do not necessarily detect toxic cereulide. Here, we developed a rapid protocol using Matrix Assisted Laser Desorption/Ionization-Time of Flight (MALDI-TOF) mass spectrometry that detects the toxin originating from a colony smear of B. cereus. The distinct molecular feature of the toxin peak at m/z 1,191 was clearly identified from bacterial extracts with a limit of detection (LOD) of 30 ng/mL. Final optimisation of the sample preparation was based on cereulide chelating cations to produce the alkali adduct [M + K]+ without the use of a MALDI matrix, and provided a 1,000-fold improvement of LOD with 30 pg/mL of cereulide. We evaluated the application of this method for the detection of cereulide in rice, milk, and different ready-to-eat meals. The proposed protocol is quick, easy and provides an improvement over conventional methods for the detection of B. cereus toxin.
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Affiliation(s)
- P J Ducrest
- University of Applied Sciences, HES-SO Valais//Wallis, Institute of Life Technologies, Sion, Switzerland
| | - S Pfammatter
- University of Montreal, Institute for Research in Immunology and Cancer, Montreal, Quebec, Canada
| | - D Stephan
- University of Applied Sciences, HES-SO Valais//Wallis, Institute of Life Technologies, Sion, Switzerland
| | - G Vogel
- Mabritec AG, Riehen, Switzerland
| | - P Thibault
- University of Montreal, Institute for Research in Immunology and Cancer, Montreal, Quebec, Canada
| | - B Schnyder
- University of Applied Sciences, HES-SO Valais//Wallis, Institute of Life Technologies, Sion, Switzerland.
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17
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Decleer M, Jovanovic J, Vakula A, Udovicki B, Agoua RSEK, Madder A, De Saeger S, Rajkovic A. Oxygen Consumption Rate Analysis of Mitochondrial Dysfunction Caused by Bacillus cereus Cereulide in Caco-2 and HepG2 Cells. Toxins (Basel) 2018; 10:E266. [PMID: 30004412 PMCID: PMC6070949 DOI: 10.3390/toxins10070266] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Revised: 06/20/2018] [Accepted: 06/22/2018] [Indexed: 12/28/2022] Open
Abstract
The emetic syndrome of Bacillus cereus is a food intoxication caused by cereulide (CER) and manifested by emesis, nausea and in most severe cases with liver failure. While acute effects have been studied in the aftermath of food intoxication, an exposure to low doses of cereulide might cause unnoticed damages to the intestines and liver. The toxicity which relies on the mitochondrial dysfunction was assessed on Caco-2 and HepG2 cells after exposure of one, three and ten days to a range of low doses of cereulide. Oxygen consumption rate analyses were used to study the impact of low doses of CER on the bioenergetics functions of undifferentiated Caco-2 and HepG2 cells using Seahorse XF extracellular flux analyzer. Both Caco-2 and HepG2 cells experienced measurable mitochondrial impairment after prolonged exposure of 10 days to 0.25 nM of cereulide. Observed mitochondrial dysfunction was greatly reflected in reduction of maximal cell respiration. At 0.50 nM CER, mitochondrial respiration was almost completely shut down, especially in HepG2 cells. These results corresponded with a severe reduction in the amount of cells and an altered morphology, observed by microscopic examination of the cells. Accurate and robust quantification of basal respiration, ATP production, proton leak, maximal respiration, spare respiratory capacity, and non-mitochondrial respiration allowed better understanding of the effects of cereulide in underlying respiratory malfunctions in low-dose exposure.
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Affiliation(s)
- Marlies Decleer
- Department of Food Technology, Food Safety and Health, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium.
- Laboratory of Food Analysis, Department of Bioanalysis, Faculty of Pharmaceutical Sciences, Ghent University, Ottergemsesteenweg 460, 9000 Ghent, Belgium.
| | - Jelena Jovanovic
- Department of Food Technology, Food Safety and Health, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium.
| | - Anita Vakula
- Department of Food Preservation Engineering, Faculty of Technology, University of Novi Sad, Bulevar Cara Lazara 1, 21000 Novi Sad, Serbia.
| | - Bozidar Udovicki
- Department of Food Safety and Food Quality Management, Faculty of Agriculture, University of Belgrade, Nemanjina 6, 11081 Zemun-Belgrade, Serbia.
| | - Rock-Seth E K Agoua
- Department of Food Technology, Food Safety and Health, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium.
| | - Annemieke Madder
- Department of Organic and Macromolecular Chemistry, Organic and Biomimetic Chemistry Research Group, Faculty of Sciences, Campus Sterre, Krijgslaan 281, Building S4, 9000 Gent, Belgium.
| | - Sarah De Saeger
- Laboratory of Food Analysis, Department of Bioanalysis, Faculty of Pharmaceutical Sciences, Ghent University, Ottergemsesteenweg 460, 9000 Ghent, Belgium.
| | - Andreja Rajkovic
- Department of Food Technology, Food Safety and Health, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium.
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18
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Lopes R, Tsui S, Gonçalves PJRO, de Queiroz MV. A look into a multifunctional toolbox: endophytic Bacillus species provide broad and underexploited benefits for plants. World J Microbiol Biotechnol 2018; 34:94. [PMID: 29900507 DOI: 10.1007/s11274-018-2479-7] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Accepted: 06/12/2018] [Indexed: 12/12/2022]
Abstract
One of the major challenges of agriculture currently is to obtain higher crop yield. Environmental conditions, cultivar quality, and plant diseases greatly affect plant productivity. On the other hand, several endophytic Bacillus species have emerged as a complementary, efficient, and safe alternative to current crop management practices. The ability of Bacillus species to form spores, which resist adverse conditions, is an advantage of the genus for use in formulations. Endophytic Bacillus species provide plants with a wide range of benefits, including protection against phytopathogenic microorganisms, insects, and nematodes, eliciting resistance, and promoting plant growth, without causing damage to the environment. Bacillus thuringiensis, B. subtilis, B. amyloliquefaciens, B. velezensis, B. cereus, B. pumilus, and B. licheniformis are the most studied Bacillus species for application in agriculture, although other species within the genus have also shown great potential. Due to the increasing number of whole-genome sequenced endophytic Bacillus spp. strains, various bioactive compounds have been predicted. These data reveal endophytic Bacillus species as an underexploited source of novel molecules of biotechnological interest. In this review, we discuss how endophytic Bacillus species are a valuable multifunctional toolbox to be integrated with crop management practices for achieving higher crop yield.
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Affiliation(s)
- Ralf Lopes
- Department of Microbiology, Institute of Biomedical Sciences, Universidade de São Paulo, 1374 Professor Lineu Prestes Avenue, São Paulo, SP, 05508-000, Brazil
| | - Sarina Tsui
- Department of Microbiology, Institute of Biomedical Sciences, Universidade de São Paulo, 1374 Professor Lineu Prestes Avenue, São Paulo, SP, 05508-000, Brazil
| | - Priscila J R O Gonçalves
- Department of Microbiology, Institute of Biomedical Sciences, Universidade de São Paulo, 1374 Professor Lineu Prestes Avenue, São Paulo, SP, 05508-000, Brazil
| | - Marisa Vieira de Queiroz
- Department of Microbiology, Institute of Biotechnology Applied to Agriculture, Universidade Federal de Viçosa, P. H. Rolfs Avenue, Viçosa, MG, 36570-900, Brazil.
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Mikkola R, Andersson MA, Grigoriev P, Heinonen M, Salkinoja-Salonen MS. The toxic mode of action of cyclic lipodepsipeptide fusaricidins, produced by Paenibacillus polymyxa, toward mammalian cells. J Appl Microbiol 2017; 123:436-449. [PMID: 28557348 DOI: 10.1111/jam.13498] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 04/28/2017] [Accepted: 05/23/2017] [Indexed: 01/09/2023]
Abstract
AIMS Toxigenic strains of Paenibacillus polymyxa were isolated from buildings connected with the symptoms of ill health. Our aim was to identify the toxic compounds of Paenibacillus polymyxa and to describe their toxic actions. METHODS AND RESULTS The toxins of Paenibacillus polymyxa were purified and analysed by HPLC and mass spectrometry. Toxic fusaricidins A and B, and LI-F05a with mass ions at m/z 883·7, 897·6 and 897·6, respectively, were found. The cytotoxicity of purified fusaricidins A and B was measured using boar sperm, porcine tubular kidney epithelial cells and murine fibroblasts. The ion channel forming properties of fusaricidins were studied using the black lipid membrane (BLM) technique. Fusaricidins A and B depolarized the mitochondria of boar sperm, porcine tubular kidney epithelial cells and murine fibroblasts at concentrations of 0·5-1 μg ml-1 and caused nuclear fragmentation and induced apoptosis at concentrations of 2·5-5 μg ml-1 . Furthermore, fusaricidins A and B induced K+ permeating single channels. CONCLUSIONS It was concluded that fusaricidins were toxic to mitochondria and induced apoptosis in mammalian cells. It was proposed that the observed toxicity of fusaricidins is due their ion channel forming properties. SIGNIFICANCE AND IMPACT OF THE STUDY This paper revealed, for the first time, the mode of action of Paenibacillus polymyxa fusaricidins toxins towards mammalian cells. Fusaricidins, due to their potassium ionophoricity and mitochondria depolarizing impacts, may have contributed to the health damage observed at sites where the producer strains were isolated at high density.
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Affiliation(s)
- R Mikkola
- Department of Civil Engineering, School of Engineering, Aalto University, Aalto, Finland
| | - M A Andersson
- Department of Civil Engineering, School of Engineering, Aalto University, Aalto, Finland.,Department of Food and Environmental Science, University of Helsinki, Helsinki, Finland
| | - P Grigoriev
- Department of Food and Environmental Science, University of Helsinki, Helsinki, Finland.,Institute of Biophysics of Cell, Russian Academy of Science, Pushchino, Moscow Region, Russia
| | - M Heinonen
- Department of Production Animal Medicine, University of Helsinki, Helsinki, Finland
| | - M S Salkinoja-Salonen
- Department of Food and Environmental Science, University of Helsinki, Helsinki, Finland
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20
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Teplova VV, Belosludtsev KN, Kruglov AG. Mechanism of triclosan toxicity: Mitochondrial dysfunction including complex II inhibition, superoxide release and uncoupling of oxidative phosphorylation. Toxicol Lett 2017; 275:108-117. [DOI: 10.1016/j.toxlet.2017.05.004] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Revised: 04/25/2017] [Accepted: 05/03/2017] [Indexed: 01/15/2023]
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21
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Salin JT, Salkinoja-Salonen M, Salin PJ, Nelo K, Holma T, Ohtonen P, Syrjälä H. Building-related symptoms are linked to the in vitro toxicity of indoor dust and airborne microbial propagules in schools: A cross-sectional study. ENVIRONMENTAL RESEARCH 2017; 154:234-239. [PMID: 28107741 DOI: 10.1016/j.envres.2017.01.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Revised: 01/10/2017] [Accepted: 01/12/2017] [Indexed: 06/06/2023]
Abstract
INTRODUCTION Indoor microbial toxicity is suspected to cause some building-related symptoms, but supporting epidemiological data are lacking. OBJECTIVE We examined whether the in vitro toxicity of indoor samples from school buildings was associated with work-related health symptoms (building-related symptoms, BRS). METHODS Administrators of the Helsinki City Real Estate Department selected 15 schools for the study, and a questionnaire on symptoms connected to work was sent to the teachers in the selected schools for voluntary completion. The cellular toxicity of classroom samples was determined by testing substances extracted from wiped indoor dust and by testing microbial biomass that was cultured on fallout plates. Boar sperm cells were used as indicator cells, and motility loss was the indicator for toxic effects. The effects were expressed as the half maximal effective concentration (EC50) at which >50% of the exposed boar sperm cells were immobile compared to vehicle control. RESULTS Completed symptom questionnaires were received from 232 teachers [median age, 43 years; 190 (82.3%) women] with a median time of 6 years working at their school. Samples from their classrooms were available and were assessed for cellular toxicity. The Poisson regression model showed that the impact of extracts of surface-wiped school classroom dust on teacher work-related BRS was 2.8-fold (95% CI: 1.6-4.9) higher in classrooms with a toxic threshold EC50 of 6µgml-1 versus classrooms with insignificant EC50 values (EC50 >50µgml-1); P<0.001. The number of symptoms that were alleviated during vacation was higher in school classrooms with high sperm toxicity compared to less toxic sites; the RR was 1.9 (95% CI: 1.1-3.3, P=0.03) for wiped dust extracts. CONCLUSIONS Teachers working in classrooms where the samples showed high sperm toxicity had more BRS. The boar sperm cell motility inhibition assay appears promising as a tool for demonstrating the presence of indoor substances associated with BRS.
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Affiliation(s)
- J T Salin
- Department of Infection Control, Oulu University Hospital, Finland
| | - M Salkinoja-Salonen
- Department of Food and Environmental Sciences, FI 00014 University of Helsinki, Finland; Department of Electrical Engineering and Automation, Aalto University, Espoo, Finland
| | - P J Salin
- Oulu University Hospital, Inspector Sec Oy Laboratories, Oulu, Finland; Department of Food and Environmental Sciences, FI 00014 University of Helsinki, Finland
| | - K Nelo
- Oulu University Hospital, Inspector Sec Oy Laboratories, Oulu, Finland
| | - T Holma
- Department of Otorhinolaryngology and Head and Neck Surgery, Oulu University Hospital, Finland; PEDEGO Research Unit, University of Oulu, Finland; Medical Research Center Oulu, Finland
| | - P Ohtonen
- Division of Operative Care and Medical Research Center, Finland
| | - H Syrjälä
- Department of Infection Control, Oulu University Hospital, Finland.
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22
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Risks for public health related to the presence of Bacillus cereus and other Bacillus spp. including Bacillus thuringiensis in foodstuffs. EFSA J 2016. [DOI: 10.2903/j.efsa.2016.4524] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
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23
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Phat C, Kim S, Park J, Lee C. Detection of Emetic Toxin Genes inBacillus cereusIsolated from Food and their Production of Cereulide in Liquid Culture. J Food Saf 2016. [DOI: 10.1111/jfs.12293] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Chanvorleak Phat
- School of Food Science and Technology; Chung-Ang University; Anseong-Si Gyeonggi-Do 456-756 Republic of Korea
| | - Suhwan Kim
- School of Food Science and Technology; Chung-Ang University; Anseong-Si Gyeonggi-Do 456-756 Republic of Korea
| | - Juhee Park
- School of Food Science and Technology; Chung-Ang University; Anseong-Si Gyeonggi-Do 456-756 Republic of Korea
| | - Chan Lee
- School of Food Science and Technology; Chung-Ang University; Anseong-Si Gyeonggi-Do 456-756 Republic of Korea
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Rasimus-Sahari S, Mikkola R, Andersson MA, Jestoi M, Salkinoja-Salonen M. Streptomyces strains producing mitochondriotoxic antimycin A found in cereal grains. Int J Food Microbiol 2016; 218:78-85. [DOI: 10.1016/j.ijfoodmicro.2015.11.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2015] [Revised: 11/06/2015] [Accepted: 11/14/2015] [Indexed: 01/28/2023]
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The Endospore-Forming Pathogen Bacillus cereus Exploits a Small Colony Variant-Based Diversification Strategy in Response to Aminoglycoside Exposure. mBio 2015; 6:e01172-15. [PMID: 26646008 PMCID: PMC4676280 DOI: 10.1128/mbio.01172-15] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Bacillus cereus is among the microorganisms most often isolated from cases of food spoilage and causes gastrointestinal diseases as well as nongastrointestinal infections elicited by the emetic toxin cereulide, enterotoxins, and a panel of tissue-destructive virulence factors. This opportunistic pathogen is increasingly associated with rapidly fatal clinical infections especially linked to neonates and immunocompromised individuals. Fatality results from either the misdiagnosis of B. cereus as a contaminant of the clinical specimen or from failure of antibiotic therapy. Here we report for the first time that exposure to aminoglycoside antibiotics induces a phenotype switching of emetic B. cereus subpopulations to a slow-growing small colony variant (SCV) state. Along with altered antibiotic resistance, SCVs showed distinct phenotypic and metabolic properties, bearing the risk of antibiotic treatment failure and of clinical misdiagnosis by standard identification tests used in routine diagnostic. The SCV subpopulation is characterized by enhanced production of the toxin cereulide, but it does not secrete tissue-destructive and immune system-affecting enzymes such as sphingomyelinase and phospholipase. SCVs showed significantly prolonged persistence and decreased virulence in the Galleria mellonella model for bacterial infections, indicating diversification concerning their ecological lifestyle. Importantly, diversification into coexisting wild-type and SCV subpopulations also emerged during amikacin pressure during in vivo infection experiments. This study shows for the first time that pathogenic spore-forming B. cereus strains are able to switch to a so far unreported slow-growing lifestyle, which differs substantially in terms of developmental, phenotypic, metabolic, and virulence traits from the wild-type populations. This underpins the necessity of molecular-based differential diagnostics and a well-chosen therapeutic treatment strategy in clinical environments to combat B. cereus in a tailored manner. The reported induction of SCV in an endospore-forming human pathogen requires further research to broaden our understanding of a yet unexplored antibiotic resistance mechanism in sporulating bacteria. Our work also raises a general question about the ecological meaning of SCV subpopulation emergence and importance of SCV in sporeformer populations as an alternative route, next to sporulation, to cope with stresses encountered in natural niches, such as soil or host interfaces.
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Ehling-Schulz M, Frenzel E, Gohar M. Food-bacteria interplay: pathometabolism of emetic Bacillus cereus. Front Microbiol 2015; 6:704. [PMID: 26236290 PMCID: PMC4500953 DOI: 10.3389/fmicb.2015.00704] [Citation(s) in RCA: 95] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2015] [Accepted: 06/26/2015] [Indexed: 11/25/2022] Open
Abstract
Bacillus cereus is a Gram-positive endospore forming bacterium known for its wide spectrum of phenotypic traits, enabling it to occupy diverse ecological niches. Although the population structure of B. cereus is highly dynamic and rather panmictic, production of the emetic B. cereus toxin cereulide is restricted to strains with specific genotypic traits, associated with distinct environmental habitats. Cereulide is an ionophoric dodecadepsipeptide that is produced non-ribosomally by an enzyme complex with an unusual modular structure, named cereulide synthetase (Ces non-ribosomal peptide synthetase). The ces gene locus is encoded on a mega virulence plasmid related to the B. anthracis toxin plasmid pXO1. Cereulide, a highly thermo- and pH- resistant molecule, is preformed in food, evokes vomiting a few hours after ingestion, and was shown to be the direct cause of gastroenteritis symptoms; occasionally it is implicated in severe clinical manifestations including acute liver failures. Control of toxin gene expression in emetic B. cereus involves central transcriptional regulators, such as CodY and AbrB, thereby inextricably linking toxin gene expression to life cycle phases and specific conditions, such as the nutrient supply encountered in food matrices. While in recent years considerable progress has been made in the molecular and biochemical characterization of cereulide toxin synthesis, far less is known about the embedment of toxin synthesis in the life cycle of B. cereus. Information about signals acting on toxin production in the food environment is lacking. We summarize the data available on the complex regulatory network controlling cereulide toxin synthesis, discuss the role of intrinsic and extrinsic factors acting on toxin biosynthesis in emetic B. cereus and stress how unraveling these processes can lead to the development of novel effective strategies to prevent toxin synthesis in the food production and processing chain.
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Affiliation(s)
- Monika Ehling-Schulz
- Functional Microbiology, Institute of Microbiology, Department of Pathobiology, University of Veterinary Medicine ViennaVienna, Austria
| | - Elrike Frenzel
- Functional Microbiology, Institute of Microbiology, Department of Pathobiology, University of Veterinary Medicine ViennaVienna, Austria
| | - Michel Gohar
- INRA, UMR1319 Micalis, AgroParistech – Domaine de Vilvert, Génétique Microbienne et EnvironnementJouy-en-Josas, France
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Vangoitsenhoven R, Maris M, Overbergh L, Van Loco J, Mathieu C, Van der Schueren B. Cereulide food toxin, beta cell function and diabetes: Facts and hypotheses. Diabetes Res Clin Pract 2015; 109:1-5. [PMID: 25998918 DOI: 10.1016/j.diabres.2015.04.029] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Accepted: 04/28/2015] [Indexed: 01/11/2023]
Abstract
The incidence of both type 1 and type 2 diabetes is increasing and although environmental pollutants are believed to be potential culprits, the extent to which they can be held responsible remains uncertain. Some bacterial strains of the Bacillus cereus produce a toxin, cereulide, which is frequently found in starchy meals and which is difficult to eradicate from the food chain as it is highly resistant to heat, acidity and proteolysis. While cereulide is well known to cause acute emetic toxicity when ingested at high doses, several in vitro studies have shown that also extremely low doses of cereulide can be toxic, with beta cells being particularly sensitive. Mechanistically, such low doses impair the mitochondrial activity of the beta cells thereby leading to hampered insulin secretion and cell death, both key traits in the pathophysiology of diabetes. In vivo studies of chronic or repeated low dose exposure to cereulide are currently lacking, but should be performed to further clarify the true relevance of cereulide as a potential environmental contributor to the ongoing diabetes epidemic.
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Affiliation(s)
| | - Michael Maris
- Clinical and Experimental Endocrinology, KU Leuven, Leuven, Belgium
| | - Lut Overbergh
- Clinical and Experimental Endocrinology, KU Leuven, Leuven, Belgium
| | - Joris Van Loco
- Scientific Institute of Public Health, Brussels, Belgium
| | - Chantal Mathieu
- Clinical and Experimental Endocrinology, KU Leuven, Leuven, Belgium
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Ajao C, Andersson MA, Teplova VV, Nagy S, Gahmberg CG, Andersson LC, Hautaniemi M, Kakasi B, Roivainen M, Salkinoja-Salonen M. Mitochondrial toxicity of triclosan on mammalian cells. Toxicol Rep 2015; 2:624-637. [PMID: 28962398 PMCID: PMC5598359 DOI: 10.1016/j.toxrep.2015.03.012] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Revised: 03/29/2015] [Accepted: 03/30/2015] [Indexed: 01/08/2023] Open
Abstract
Effects of triclosan (5-chloro-2'-(2,4-dichlorophenoxy)phenol) on mammalian cells were investigated using human peripheral blood mono nuclear cells (PBMC), keratinocytes (HaCaT), porcine spermatozoa and kidney tubular epithelial cells (PK-15), murine pancreatic islets (MIN-6) and neuroblastoma cells (MNA) as targets. We show that triclosan (1-10 μg ml-1) depolarised the mitochondria, upshifted the rate of glucose consumption in PMBC, HaCaT, PK-15 and MNA, and subsequently induced metabolic acidosis. Triclosan induced a regression of insulin producing pancreatic islets into tiny pycnotic cells and necrotic death. Short exposure to low concentrations of triclosan (30 min, ≤1 μg/ml) paralyzed the high amplitude tail beating and progressive motility of spermatozoa, within 30 min exposure, depolarized the spermatozoan mitochondria and hyperpolarised the acrosome region of the sperm head and the flagellar fibrous sheath (distal part of the flagellum). Experiments with isolated rat liver mitochondria showed that triclosan impaired oxidative phosphorylation, downshifted ATP synthesis, uncoupled respiration and provoked excessive oxygen uptake. These exposure concentrations are 100-1000 fold lower that those permitted in consumer goods. The mitochondriotoxic mechanism of triclosan differs from that of valinomycin, cereulide and the enniatins by not involving potassium ionophoric activity.
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Key Words
- Acidosis
- BCF, bioconcentration factor
- EC50, concentration that diminishes the respective vitality parameter by ≥50%
- Electric transmembrane potential
- Glycolysis
- HaCaT, a spontaneously immortalized (non-neoplastic) keratinocyte cell line
- JC-1, 5,5′,6,6′-tetrachloro-1,1′,3,3′-tetraethylbenzimidazolyl-carbocyanine iodide
- MIC, minimal inhibitory concentration
- MIN-6, a murine pancreatic beta cell line
- MNA, a murine neuroblastoma cells
- Oxidative phosphorylation
- PBMC, monocyte-enriched peripheral blood mononuclear cells
- PI, propidium iodide
- PK-15, a porcine kidney tubular epithelial cell line
- PN, pyridine nucleotides
- RLM, rat liver mitochondria
- Sperm motility
- TPP+, tetraphenylphosphonium
- Uncoupler
- ΔΨ, electric transmembrane potential
- ΔΨm, membrane potential of the mitochondrial membrane
- ΔΨp, membrane potential of the plasma membrane
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Affiliation(s)
- Charmaine Ajao
- Department of Food and Environmental Sciences, Haartman Institute, University of Helsinki, POB 56, FI-00014, Finland
| | - Maria A. Andersson
- Department of Food and Environmental Sciences, Haartman Institute, University of Helsinki, POB 56, FI-00014, Finland
| | - Vera V. Teplova
- Institute of Theoretical and Experimental Biophysics, RAS, Puschino, Moscow Region, Russia
| | - Szabolcs Nagy
- Department of Animal Science and Animal Husbandry, University of Pannonia, Georgikon Faculty, Deak F. u.,16, H8360 Keszthely, Hungary
| | - Carl G. Gahmberg
- Dept. of Bio- and Environmental Sciences, Haartman Institute, University of Helsinki, FI-00014, Finland
| | - Leif C. Andersson
- Dept. of Pathology, Haartman Institute, University of Helsinki, FI-00014, Finland
| | - Maria Hautaniemi
- Finnish Food Safety Authority (EVIRA), Research and Laboratory Department, Veterinary Virology Research Unit, Mustialankatu 3, FI 00790 Helsinki, Finland
| | - Balazs Kakasi
- Institute of Environmental Sciences, University of Pannonia, Egyetem u. 10, H-8200 Veszprem, Hungary
| | - Merja Roivainen
- National Institute for Health and Welfare, Department of Virology, Mannerheimintie 166, 00300 Helsinki, Finland
| | - Mirja Salkinoja-Salonen
- Department of Food and Environmental Sciences, Haartman Institute, University of Helsinki, POB 56, FI-00014, Finland
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The peptide toxin amylosin of Bacillus amyloliquefaciens from moisture-damaged buildings is immunotoxic, induces potassium efflux from mammalian cells, and has antimicrobial activity. Appl Environ Microbiol 2015; 81:2939-49. [PMID: 25681192 DOI: 10.1128/aem.03430-14] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Amylosin, a heat-stable channel-forming non-ribosomally synthesized peptide toxin produced by strains of Bacillus amyloliquefaciens isolated from moisture-damaged buildings, is shown in this paper to have immunotoxic and cytotoxic effects on human cells as well as antagonistic effects on microbes. Human macrophages exposed to 50 ng of amylosin ml(-1) secreted high levels of cytokines interleukin-1β (IL-1β) and IL-18 within 2 h, indicating activation of the NLRP3 inflammasome, an integral part of the innate immune system. At the same exposure level, expression of IL-1β and IL-18 mRNA increased. Amylosin caused dose-dependent potassium ion efflux from all tested mammalian cells (human monocytes and keratinocytes and porcine sperm cells) at 1 to 2 μM exposure. Amylosin also inhibited the motility of porcine sperm cells and depolarized the mitochondria of human keratinocytes. Amylosin may thus trigger the activation of the NLRP3 inflammasome and subsequently cytokine release by causing potassium efflux from exposed cells. The results of this study indicate that exposure to amylosin activates the innate immune system, which could offer an explanation for the inflammatory symptoms experienced by occupants of moisture-damaged buildings. In addition, the amylosin-producing B. amyloliquefaciens inhibited the growth of both prokaryotic and eukaryotic indoor microbes, and purified amylosin also had an antimicrobial effect. These antimicrobial effects could make amylosin producers dominant and therefore significant causal agents of health problems in some moisture-damaged sites.
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Vangoitsenhoven R, Rondas D, Crèvecoeur I, D'Hertog W, Baatsen P, Masini M, Andjelkovic M, Van Loco J, Matthys C, Mathieu C, Overbergh L, Van der Schueren B. Foodborne cereulide causes beta-cell dysfunction and apoptosis. PLoS One 2014; 9:e104866. [PMID: 25119564 PMCID: PMC4132018 DOI: 10.1371/journal.pone.0104866] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Accepted: 07/14/2014] [Indexed: 01/10/2023] Open
Abstract
Aims/Hypothesis To study the effects of cereulide, a food toxin often found at low concentrations in take-away meals, on beta-cell survival and function. Methods Cell death was quantified by Hoechst/Propidium Iodide in mouse (MIN6) and rat (INS-1E) beta-cell lines, whole mouse islets and control cell lines (HepG2 and COS-1). Beta-cell function was studied by glucose-stimulated insulin secretion (GSIS). Mechanisms of toxicity were evaluated in MIN6 cells by mRNA profiling, electron microscopy and mitochondrial function tests. Results 24 h exposure to 5 ng/ml cereulide rendered almost all MIN6, INS-1E and pancreatic islets apoptotic, whereas cell death did not increase in the control cell lines. In MIN6 cells and murine islets, GSIS capacity was lost following 24 h exposure to 0.5 ng/ml cereulide (P<0.05). Cereulide exposure induced markers of mitochondrial stress including Puma (p53 up-regulated modulator of apoptosis, P<0.05) and general pro-apoptotic signals as Chop (CCAAT/-enhancer-binding protein homologous protein). Mitochondria appeared swollen upon transmission electron microscopy, basal respiration rate was reduced by 52% (P<0.05) and reactive oxygen species increased by more than twofold (P<0.05) following 24 h exposure to 0.25 and 0.50 ng/ml cereulide, respectively. Conclusions/Interpretation Cereulide causes apoptotic beta-cell death at low concentrations and impairs beta-cell function at even lower concentrations, with mitochondrial dysfunction underlying these defects. Thus, exposure to cereulide even at concentrations too low to cause systemic effects appears deleterious to the beta-cell.
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Affiliation(s)
- Roman Vangoitsenhoven
- Laboratory for Clinical and Experimental Medicine and Endocrinology, KU Leuven, Leuven, Belgium
| | - Dieter Rondas
- Laboratory for Clinical and Experimental Medicine and Endocrinology, KU Leuven, Leuven, Belgium
| | - Inne Crèvecoeur
- Laboratory for Clinical and Experimental Medicine and Endocrinology, KU Leuven, Leuven, Belgium
| | - Wannes D'Hertog
- Laboratory for Clinical and Experimental Medicine and Endocrinology, KU Leuven, Leuven, Belgium
| | - Pieter Baatsen
- EM Facility, VIB Bio Imaging Core and VIB department for the Biology of Disease, KU Leuven, Leuven, Belgium
| | - Matilde Masini
- Department of Translational Research and of New Surgical and Medical Technologies, University of Pisa, Pisa, Italy
| | - Mirjana Andjelkovic
- Food, Medicines, and Consumer Safety, Scientific Institute of Public Health, Brussels, Belgium
| | - Joris Van Loco
- Food, Medicines, and Consumer Safety, Scientific Institute of Public Health, Brussels, Belgium
| | - Christophe Matthys
- Laboratory for Clinical and Experimental Medicine and Endocrinology, KU Leuven, Leuven, Belgium
| | - Chantal Mathieu
- Laboratory for Clinical and Experimental Medicine and Endocrinology, KU Leuven, Leuven, Belgium
| | - Lut Overbergh
- Laboratory for Clinical and Experimental Medicine and Endocrinology, KU Leuven, Leuven, Belgium
| | - Bart Van der Schueren
- Laboratory for Clinical and Experimental Medicine and Endocrinology, KU Leuven, Leuven, Belgium
- * E-mail:
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