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The Morphogenetic Protein CotE Positions Exosporium Proteins CotY and ExsY during Sporulation of Bacillus cereus. mSphere 2021; 6:6/2/e00007-21. [PMID: 33883264 PMCID: PMC8546674 DOI: 10.1128/msphere.00007-21] [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: 12/02/2022] Open
Abstract
The exosporium is the outermost spore layer of some Bacillus and Clostridium species and related organisms. It mediates the interactions of spores with their environment, modulates spore adhesion and germination, and has been implicated in pathogenesis. In Bacillus cereus, the exosporium consists of a crystalline basal layer, formed mainly by the two cysteine-rich proteins CotY and ExsY, surrounded by a hairy nap composed of glycoproteins. The morphogenetic protein CotE is necessary for the integrity of the B. cereus exosporium, but how CotE directs exosporium assembly remains unknown. Here, we used super-resolution fluorescence microscopy to follow the localization of SNAP-tagged CotE, CotY, and ExsY during B. cereus sporulation and evidenced the interdependencies among these proteins. Complexes of CotE, CotY, and ExsY are present at all sporulation stages, and the three proteins follow similar localization patterns during endospore formation that are reminiscent of the localization pattern of Bacillus subtilis CotE. We show that B. cereus CotE guides the formation of one cap at both forespore poles by positioning CotY and then guides forespore encasement by ExsY, thereby promoting exosporium elongation. By these two actions, CotE ensures the formation of a complete exosporium. Importantly, we demonstrate that the assembly of the exosporium is not a unidirectional process, as previously proposed, but occurs through the formation of two caps, as observed during B. subtilis coat morphogenesis, suggesting that a general principle governs the assembly of the spore surface layers of Bacillaceae. IMPORTANCE Spores of Bacillaceae are enveloped in an outermost glycoprotein layer. In the B. cereus group, encompassing the Bacillus anthracis and B. cereus pathogens, this layer is easily recognizable by a characteristic balloon-like appearance and separation from the underlying coat by an interspace. In spite of its importance for the environmental interactions of spores, including those with host cells, the mechanism of assembly of the exosporium is poorly understood. We used super-resolution fluorescence microscopy to directly visualize the formation of the exosporium during the sporulation of B. cereus, and we studied the localization and interdependencies of proteins essential for exosporium morphogenesis. We discovered that these proteins form a morphogenetic scaffold before a complete exosporium or coat is detectable. We describe how the different proteins localize to the scaffold and how they subsequently assemble around the spore, and we present a model for the assembly of the exosporium.
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Qiu Y, Zhai C, Chen L, Liu X, Yeo J. Current Insights on the Diverse Structures and Functions in Bacterial Collagen-like Proteins. ACS Biomater Sci Eng 2021. [PMID: 33871954 DOI: 10.1021/acsbiomaterials.1c00018] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The dearth of knowledge on the diverse structures and functions in bacterial collagen-like proteins is in stark contrast to the deep grasp of structures and functions in mammalian collagen, the ubiquitous triple-helical scleroprotein that plays a central role in tissue architecture, extracellular matrix organization, and signal transduction. To fill and highlight existing gaps due to the general paucity of data on bacterial CLPs, we comprehensively reviewed the latest insight into their functional and structural diversity from multiple perspectives of biology, computational simulations, and materials engineering. The origins and discovery of bacterial CLPs were explored. Their genetic distribution and molecular architecture were analyzed, and their structural and functional diversity in various bacterial genera was examined. The principal roles of computational techniques in understanding bacterial CLPs' structural stability, mechanical properties, and biological functions were also considered. This review serves to drive further interest and development of bacterial CLPs, not only for addressing fundamental biological problems in collagen but also for engineering novel biomaterials. Hence, both biology and materials communities will greatly benefit from intensified research into the diverse structures and functions in bacterial collagen-like proteins.
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Affiliation(s)
- Yimin Qiu
- National Biopesticide Engineering Technology Research Center, Hubei Biopesticide Engineering Research Center, Hubei Academy of Agricultural Sciences, Biopesticide Branch of Hubei Innovation Centre of Agricultural Science and Technology, Wuhan 430064, PR China.,State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, Wuhan 430062, PR China
| | - Chenxi Zhai
- J2 Lab for Engineering Living Materials, Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, New York 14850, United States
| | - Ling Chen
- National Biopesticide Engineering Technology Research Center, Hubei Biopesticide Engineering Research Center, Hubei Academy of Agricultural Sciences, Biopesticide Branch of Hubei Innovation Centre of Agricultural Science and Technology, Wuhan 430064, PR China
| | - Xiaoyan Liu
- National Biopesticide Engineering Technology Research Center, Hubei Biopesticide Engineering Research Center, Hubei Academy of Agricultural Sciences, Biopesticide Branch of Hubei Innovation Centre of Agricultural Science and Technology, Wuhan 430064, PR China
| | - Jingjie Yeo
- J2 Lab for Engineering Living Materials, Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, New York 14850, United States
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Bacterial Spore-Based Hygromorphs: A Novel Active Material with Potential for Architectural Applications. SUSTAINABILITY 2021. [DOI: 10.3390/su13074030] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
This paper introduces a new active material which responds to changes in environmental humidity. There has been growing interest in active materials which are able to respond to their environment, creating dynamic architectural systems without the need for energy input or complex systems of sensors and actuators. A subset of these materials are hygromorphs, which respond to changes in relative humidity (RH) and wetting through shape change. Here, we introduce a novel hygromorphic material in the context of architectural design, composed of multiple monolayers of microbial spores of Bacillus subtilis and latex sheets. Methods of fabrication and testing for this new material are described, showing that small actuators made from this material demonstrate rapid, reversible and repeatable deflection in response to changes in RH. It is demonstrated that the hygromorphic actuators are able to lift at least 150% of their own mass. Investigations are also extended to understanding this new biomaterial in terms of meaningful work.
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54
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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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Updegrove TB, Harke J, Anantharaman V, Yang J, Gopalan N, Wu D, Piszczek G, Stevenson DM, Amador-Noguez D, Wang JD, Aravind L, Ramamurthi KS. Reformulation of an extant ATPase active site to mimic ancestral GTPase activity reveals a nucleotide base requirement for function. eLife 2021; 10:65845. [PMID: 33704064 PMCID: PMC7952092 DOI: 10.7554/elife.65845] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 02/05/2021] [Indexed: 12/23/2022] Open
Abstract
Hydrolysis of nucleoside triphosphates releases similar amounts of energy. However, ATP hydrolysis is typically used for energy-intensive reactions, whereas GTP hydrolysis typically functions as a switch. SpoIVA is a bacterial cytoskeletal protein that hydrolyzes ATP to polymerize irreversibly during Bacillus subtilis sporulation. SpoIVA evolved from a TRAFAC class of P-loop GTPases, but the evolutionary pressure that drove this change in nucleotide specificity is unclear. We therefore reengineered the nucleotide-binding pocket of SpoIVA to mimic its ancestral GTPase activity. SpoIVAGTPase functioned properly as a GTPase but failed to polymerize because it did not form an NDP-bound intermediate that we report is required for polymerization. Further, incubation of SpoIVAGTPase with limiting ATP did not promote efficient polymerization. This approach revealed that the nucleotide base, in addition to the energy released from hydrolysis, can be critical in specific biological functions. We also present data suggesting that increased levels of ATP relative to GTP at the end of sporulation was the evolutionary pressure that drove the change in nucleotide preference in SpoIVA.
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Affiliation(s)
- Taylor B Updegrove
- Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, United States
| | - Jailynn Harke
- Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, United States
| | - Vivek Anantharaman
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, United States
| | - Jin Yang
- Department of Bacteriology, University of Wisconsin, Madison, United States
| | - Nikhil Gopalan
- Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, United States
| | - Di Wu
- Biophysics Core Facility, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, United States
| | - Grzegorz Piszczek
- Biophysics Core Facility, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, United States
| | - David M Stevenson
- Department of Bacteriology, University of Wisconsin, Madison, United States
| | | | - Jue D Wang
- Department of Bacteriology, University of Wisconsin, Madison, United States
| | - L Aravind
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, United States
| | - Kumaran S Ramamurthi
- Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, United States
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56
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Bassères E, Endres BT, Montes-Bravo N, Pérez-Soto N, Rashid T, Lancaster C, Begum K, Alam MJ, Paredes-Sabja D, Garey KW. Visualization of fidaxomicin association with the exosporium layer of Clostridioides difficile spores. Anaerobe 2021; 69:102352. [PMID: 33640461 DOI: 10.1016/j.anaerobe.2021.102352] [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] [Received: 01/13/2021] [Revised: 02/18/2021] [Accepted: 02/19/2021] [Indexed: 11/17/2022]
Abstract
BACKGROUND Fidaxomicin has novel pharmacologic effects on C. difficile spore formation including outgrowth inhibition and persistent spore attachment. However, the mechanism of fidaxomicin attachment on spores has not undergone rigorous microscopic studies. MATERIALS & METHODS Fidaxomicin attachment to C. difficile spores of three distinct ribotypes and C. difficile mutant spores with inactivation of exosporium or spore-coat protein-coding genes were visualized using confocal microscopy with a fidaxomicin-bodipy compound (green fluorescence). The pharmacologic effect of the fidaxomicin-bodipy compound was determined. Confocal microscopy experiments included direct effect on C. difficile wild-type and mutant spores, effect of exosporium removal, and direct attachment to a comparator spore forming organism, Bacillus subtilis. RESULTS The fidaxomicin-bodipy compound MIC was 1 mg/L compared to 0.06 mg/L for unlabeled fidaxomicin, a 16-fold increase. Using confocal microscopy, the intracellular localization of fidaxomicin into vegetative C. difficile cells was observed consistent with its RNA polymerase mechanism of action and inhibited spore outgrowth. The fidaxomicin-bodipy compound was visualized outside of the core of C. difficile spores with no co-localization with the membrane staining dye FM4-64. Exosporium removal reduced fidaxomicin-bodipy association with C. difficile spores. Reduced fidaxomicin-bodipy was observed in C. difficile mutant spores for the spore surface proteins CdeC and CotE. CONCLUSION This study visualized a direct attachment of fidaxomicin to C. difficile spores that was diminished with mutants of specific exosporium and spore coat proteins. These data provide advanced insight regarding the anti-spore properties of fidaxomicin.
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Affiliation(s)
| | | | - Nicolás Montes-Bravo
- Microbiota-Host Interactions and Clostridia Research Group, Facultad de Ciencias de La Vida, Universidad Andrés Bello, Santiago, Chile; ANID - Millennium Science Initiative Program - Millennium Nucleus in the Biology of the Intestinal Microbiota, Santiago, Chile
| | - Nicolás Pérez-Soto
- Microbiota-Host Interactions and Clostridia Research Group, Facultad de Ciencias de La Vida, Universidad Andrés Bello, Santiago, Chile; ANID - Millennium Science Initiative Program - Millennium Nucleus in the Biology of the Intestinal Microbiota, Santiago, Chile
| | - Tasnuva Rashid
- University of Houston College of Pharmacy, Houston, TX, USA
| | | | - Khurshida Begum
- University of Houston College of Pharmacy, Houston, TX, USA.
| | | | - Daniel Paredes-Sabja
- Microbiota-Host Interactions and Clostridia Research Group, Facultad de Ciencias de La Vida, Universidad Andrés Bello, Santiago, Chile; ANID - Millennium Science Initiative Program - Millennium Nucleus in the Biology of the Intestinal Microbiota, Santiago, Chile; Department of Biology, Texas A&M University, College Station, TX, 77843, USA
| | - Kevin W Garey
- University of Houston College of Pharmacy, Houston, TX, USA.
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57
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Egan M, Dempsey E, Ryan CA, Ross RP, Stanton C. The Sporobiota of the Human Gut. Gut Microbes 2021; 13:1-17. [PMID: 33406976 PMCID: PMC7801112 DOI: 10.1080/19490976.2020.1863134] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 12/01/2020] [Accepted: 12/04/2020] [Indexed: 02/04/2023] Open
Abstract
The human gut microbiome is a diverse and complex ecosystem that plays a critical role in health and disease. The composition of the gut microbiome has been well studied across all stages of life. In recent years, studies have investigated the production of endospores by specific members of the gut microbiome. An endospore is a tough, dormant structure formed by members of the Firmicutes phylum, which allows for greater resistance to otherwise inhospitable conditions. This innate resistance has consequences for human health and disease, as well as in biotechnology. In particular, the formation of endospores is strongly linked to antibiotic resistance and the spread of antibiotic resistance genes, also known as the resistome. The term sporobiota has been used to define the spore-forming cohort of a microbial community. In this review, we present an overview of the current knowledge of the sporobiota in the human gut. We discuss the development of the sporobiota in the infant gut and the perinatal factors that may have an effect on vertical transmission from mother to infant. Finally, we examine the sporobiota of critically important food sources for the developing infant, breast milk and powdered infant formula.
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Affiliation(s)
- Muireann Egan
- Food Biosciences Department, Teagasc Food Research Centre, Moorepark, Fermoy, Co. Cork, Ireland
- APC Microbiome Ireland, University College Cork, Cork, Ireland
| | - Eugene Dempsey
- APC Microbiome Ireland, University College Cork, Cork, Ireland
- Department of Neonatology, Cork University Maternity Hospital, Cork, Ireland
| | - C. Anthony Ryan
- APC Microbiome Ireland, University College Cork, Cork, Ireland
- Department of Neonatology, Cork University Maternity Hospital, Cork, Ireland
| | - R. Paul Ross
- APC Microbiome Ireland, University College Cork, Cork, Ireland
| | - Catherine Stanton
- Food Biosciences Department, Teagasc Food Research Centre, Moorepark, Fermoy, Co. Cork, Ireland
- APC Microbiome Ireland, University College Cork, Cork, Ireland
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58
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Freitas C, Plannic J, Isticato R, Pelosi A, Zilhão R, Serrano M, Baccigalupi L, Ricca E, Elsholz AKW, Losick R, O. Henriques A. A protein phosphorylation module patterns the Bacillus subtilis spore outer coat. Mol Microbiol 2020; 114:934-951. [PMID: 32592201 PMCID: PMC7821199 DOI: 10.1111/mmi.14562] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2019] [Revised: 06/17/2020] [Indexed: 01/09/2023]
Abstract
Assembly of the Bacillus subtilis spore coat involves over 80 proteins which self-organize into a basal layer, a lamellar inner coat, a striated electrodense outer coat and a more external crust. CotB is an abundant component of the outer coat. The C-terminal moiety of CotB, SKRB , formed by serine-rich repeats, is polyphosphorylated by the Ser/Thr kinase CotH. We show that another coat protein, CotG, with a central serine-repeat region, SKRG , interacts with the C-terminal moiety of CotB and promotes its phosphorylation by CotH in vivo and in a heterologous system. CotG itself is phosphorylated by CotH but phosphorylation is enhanced in the absence of CotB. Spores of a strain producing an inactive form of CotH, like those formed by a cotG deletion mutant, lack the pattern of electrondense outer coat striations, but retain the crust. In contrast, deletion of the SKRB region, has no major impact on outer coat structure. Thus, phosphorylation of CotG by CotH is a key factor establishing the structure of the outer coat. The presence of the cotB/cotH/cotG cluster in several species closely related to B. subtilis hints at the importance of this protein phosphorylation module in the morphogenesis of the spore surface layers.
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Affiliation(s)
- Carolina Freitas
- Instituto de Tecnologia Química e BiológicaUniversidade Nova de LisboaOeirasPortugal
- Present address:
Department of EcophysiologyMax‐Planck Institute for Terrestrial MicrobiologyKarl‐von‐Frisch‐Str. 10MarburgD‐35043Germany
| | - Jarnaja Plannic
- Instituto de Tecnologia Química e BiológicaUniversidade Nova de LisboaOeirasPortugal
- University of LjubljanaLjubljanaSlovenia
| | | | | | - Rita Zilhão
- Instituto de Tecnologia Química e BiológicaUniversidade Nova de LisboaOeirasPortugal
- Departamento de Biologia VegetalUniversidade de LisboaLisboaPortugal
| | - Mónica Serrano
- Instituto de Tecnologia Química e BiológicaUniversidade Nova de LisboaOeirasPortugal
| | | | - Ezio Ricca
- Department of BiologyUniversity Federico IINaplesItaly
| | - Alexander K. W. Elsholz
- Biological LaboratoriesHarvard UniversityCambridgeMAUSA
- Present address:
Max Planck Unit for the Science of PathogensCharitèplatz 1Berlin10117Germany
| | | | - Adriano O. Henriques
- Instituto de Tecnologia Química e BiológicaUniversidade Nova de LisboaOeirasPortugal
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59
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Barreto HC, Cordeiro TN, Henriques AO, Gordo I. Rampant loss of social traits during domestication of a Bacillus subtilis natural isolate. Sci Rep 2020; 10:18886. [PMID: 33144634 PMCID: PMC7642357 DOI: 10.1038/s41598-020-76017-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 10/22/2020] [Indexed: 12/16/2022] Open
Abstract
Most model bacteria have been domesticated in laboratory conditions. Yet, the tempo with which a natural isolate diverges from its ancestral phenotype under domestication to a novel laboratory environment is poorly understood. Such knowledge, however is essential to understanding the rate of evolution, the time scale over which a natural isolate can be propagated without loss of its natural adaptive traits, and the reliability of experimental results across labs. Using experimental evolution, phenotypic assays, and whole-genome sequencing, we show that within a week of propagation in a common laboratory environment, a natural isolate of Bacillus subtilis acquires mutations that cause changes in a multitude of traits. A single adaptive mutational step in the gene coding for the transcriptional regulator DegU impairs a DegU-dependent positive autoregulatory loop and leads to loss of robust biofilm architecture, impaired swarming motility, reduced secretion of exoproteases, and to changes in the dynamics of sporulation across environments. Importantly, domestication also resulted in improved survival when the bacteria face pressure from cells of the innate immune system. These results show that degU is a target for mutations during domestication and underscores the importance of performing careful and extremely short-term propagations of natural isolates to conserve the traits encoded in their original genomes.
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Affiliation(s)
- Hugo C Barreto
- Instituto Gulbenkian de Ciência, Oeiras, Portugal.,Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Tiago N Cordeiro
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Adriano O Henriques
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal.
| | - Isabel Gordo
- Instituto Gulbenkian de Ciência, Oeiras, Portugal.
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Ugwuodo CJ, Nwagu TN. Stabilizing enzymes by immobilization on bacterial spores: A review of literature. Int J Biol Macromol 2020; 166:238-250. [PMID: 33115650 DOI: 10.1016/j.ijbiomac.2020.10.171] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 10/16/2020] [Accepted: 10/21/2020] [Indexed: 10/23/2022]
Abstract
The ever-increasing applications of enzymes are limited by the relatively poor performance in harsh processing conditions. As a result, there are constant innovations in immobilization protocols for improving biocatalyst activity and stability. Bacterial spores are cheap to generate and highly resistant to environmental stress. The spore core is sheathed by an inner membrane, the germ cell wall, the cortex, outer membrane, spore coat and in some species the exosporium. The spore surface is anion-rich, hydrophobic and contains several reactive groups capable of interacting and stabilizing enzyme molecules through electrostatic forces, hydrophobic interactions and covalent bonding. The probiotic nature of spores obtained from non-toxic bacterial species makes them suitable carriers for the enzyme immobilization, especially food-grade enzymes or those intended for therapeutic use. Immobilization on spores is by direct adsorption, covalent attachment or surface display during the sporulation phase. Hindrances to the immobilization on spore matrix include the production rates, operational instability, and reduced catalytic properties due to conformational changes in enzyme. This paper reviews bacterial spore as a heterofunctional support matrix gives reasons why probiotic bacillus spores are better options and the diverse technologies adopted for spore-enzyme immobilization. It further suggests directions for future use and discusses the commercialization prospects.
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Secaira-Morocho H, Castillo JA, Driks A. Diversity and evolutionary dynamics of spore-coat proteins in spore-forming species of Bacillales. Microb Genom 2020; 6. [PMID: 33052805 PMCID: PMC7725329 DOI: 10.1099/mgen.0.000451] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Among members of the Bacillales order, there are several species capable of forming a structure called an endospore. Endospores enable bacteria to survive under unfavourable growth conditions and germinate when environmental conditions are favourable again. Spore-coat proteins are found in a multilayered proteinaceous structure encasing the spore core and the cortex. They are involved in coat assembly, cortex synthesis and germination. Here, we aimed to determine the diversity and evolutionary processes that have influenced spore-coat genes in various spore-forming species of Bacillales using an in silico approach. For this, we used sequence similarity searching algorithms to determine the diversity of coat genes across 161 genomes of Bacillales. The results suggest that among Bacillales, there is a well-conserved core genome, composed mainly by morphogenetic coat proteins and spore-coat proteins involved in germination. However, some spore-coat proteins are taxa-specific. The best-conserved genes among different species may promote adaptation to changeable environmental conditions. Because most of the Bacillus species harbour complete or almost complete sets of spore-coat genes, we focused on this genus in greater depth. Phylogenetic reconstruction revealed eight monophyletic groups in the Bacillus genus, of which three are newly discovered. We estimated the selection pressures acting over spore-coat genes in these monophyletic groups using classical and modern approaches and detected horizontal gene transfer (HGT) events, which have been further confirmed by scanning the genomes to find traces of insertion sequences. Although most of the genes are under purifying selection, there are several cases with individual sites evolving under positive selection. Finally, the HGT results confirm that sporulation is an ancestral feature in Bacillus.
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Affiliation(s)
- Henry Secaira-Morocho
- School of Biological Sciences and Engineering, Yachay Tech University, San Miguel de Urcuquí, Imbabura, Ecuador
| | - José A Castillo
- School of Biological Sciences and Engineering, Yachay Tech University, San Miguel de Urcuquí, Imbabura, Ecuador
| | - Adam Driks
- Department of Microbiology and Immunology, Loyola University Chicago, Chicago, IL, USA
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Role of SpoIVA ATPase Motifs during Clostridioides difficile Sporulation. J Bacteriol 2020; 202:JB.00387-20. [PMID: 32817091 PMCID: PMC7549369 DOI: 10.1128/jb.00387-20] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 08/04/2020] [Indexed: 01/04/2023] Open
Abstract
The major pathogen Clostridioides difficile depends on its spore form to transmit disease. However, the mechanism by which C. difficile assembles spores remains poorly characterized. We previously showed that binding between the spore morphogenetic proteins SpoIVA and SipL regulates assembly of the protective coat layer around the forespore. In this study, we determined that mutations in the C. difficile SpoIVA ATPase motifs result in relatively minor defects in spore formation, in contrast with Bacillus subtilis. Nevertheless, our data suggest that SipL preferentially recognizes the ATP-bound form of SpoIVA and identify a specific residue in the SipL C-terminal LysM domain that is critical for recognizing the ATP-bound form of SpoIVA. These findings advance our understanding of how SpoIVA-SipL interactions regulate C. difficile spore assembly. The nosocomial pathogen Clostridioides difficile is a spore-forming obligate anaerobe that depends on its aerotolerant spore form to transmit infections. Functional spore formation depends on the assembly of a proteinaceous layer known as the coat around the developing spore. In C. difficile, coat assembly depends on the conserved spore protein SpoIVA and the clostridial-organism-specific spore protein SipL, which directly interact. Mutations that disrupt their interaction cause the coat to mislocalize and impair spore formation. In Bacillus subtilis, SpoIVA is an ATPase that uses ATP hydrolysis to drive its polymerization around the forespore. Loss of SpoIVA ATPase activity impairs B. subtilis SpoIVA encasement of the forespore and activates a quality control mechanism that eliminates these defective cells. Since this mechanism is lacking in C. difficile, we tested whether mutations in the C. difficile SpoIVA ATPase motifs impact functional spore formation. Disrupting C. difficile SpoIVA ATPase motifs resulted in phenotypes that were typically >104-fold less severe than the equivalent mutations in B. subtilis. Interestingly, mutation of ATPase motif residues predicted to abrogate SpoIVA binding to ATP decreased the SpoIVA-SipL interaction, whereas mutation of ATPase motif residues predicted to disrupt ATP hydrolysis but maintain ATP binding enhanced the SpoIVA-SipL interaction. When a sipL mutation known to reduce binding to SpoIVA was combined with a spoIVA mutation predicted to prevent SpoIVA binding to ATP, spore formation was severely exacerbated. Since this phenotype is allele specific, our data imply that SipL recognizes the ATP-bound form of SpoIVA and highlight the importance of this interaction for functional C. difficile spore formation. IMPORTANCE The major pathogen Clostridioides difficile depends on its spore form to transmit disease. However, the mechanism by which C. difficile assembles spores remains poorly characterized. We previously showed that binding between the spore morphogenetic proteins SpoIVA and SipL regulates assembly of the protective coat layer around the forespore. In this study, we determined that mutations in the C. difficile SpoIVA ATPase motifs result in relatively minor defects in spore formation, in contrast with Bacillus subtilis. Nevertheless, our data suggest that SipL preferentially recognizes the ATP-bound form of SpoIVA and identify a specific residue in the SipL C-terminal LysM domain that is critical for recognizing the ATP-bound form of SpoIVA. These findings advance our understanding of how SpoIVA-SipL interactions regulate C. difficile spore assembly.
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Ziegler I, Vollmar P, Knüpfer M, Braun P, Stoecker K. Reevaluating limits of detection of 12 lateral flow immunoassays for the detection of Yersinia pestis, Francisella tularensis, and Bacillus anthracis spores using viable risk group-3 strains. J Appl Microbiol 2020; 130:1173-1180. [PMID: 32970936 DOI: 10.1111/jam.14863] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 08/28/2020] [Accepted: 09/17/2020] [Indexed: 11/27/2022]
Abstract
AIM Rapid detection of biological agents in biodefense is critical for operational, tactical and strategic levels as well as for medical countermeasures. Yersinia pestis, Francisella tularensis, and Bacillus anthracis are high priority agents of biological warfare or bioterrorism and many response forces use lateral flow assays (LFAs) for their detection. Several companies produce these assays, which offer results in short time and are easy to use. Despite their importance, only few publications on the limits of detection (LOD) for LFAs are available. Most of these studies used inactivated bacteria or risk group-2 strains. As the inactivation process in previous studies might have affected the tests' performances, it was our aim in this study to determine and compare the LOD of several commercially available LFAs using viable risk group-3 strains. METHODS AND RESULTS Lateral flow assays from four different companies for the detection of following bacteria were evaluated: Y. pestis, F. tularensis and B. anthracis spores. Two independent quantification methods for each target organism were applied, in order to ensure high quantification accuracy. LODs varied greatly between tests and organisms and ranged between 104 for Y. pestis-tests and as high as >109 for one B. anthracis-test. CONCLUSION This work precisely determined the LODs of LFAs from four commercial suppliers. The herein determined LODs differed from results of previous studies. This illustrates the need for using accurately quantified viable risk group 3-strains for determining such LODs. SIGNIFICANCE AND IMPACT OF THE STUDY Our work bridges an important knowledge gap with regard to LFA LOD. The LODs determined in this study will facilitate better assessment of LFA-results. They illustrate that a negative LFA result is not suited to exclude the presence of the respective agent in the analyzed sample.
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Affiliation(s)
- I Ziegler
- Bundeswehr Institute for Microbiology, Munich, Germany
| | - P Vollmar
- Bundeswehr Institute for Microbiology, Munich, Germany
| | - M Knüpfer
- Bundeswehr Institute for Microbiology, Munich, Germany
| | - P Braun
- Bundeswehr Institute for Microbiology, Munich, Germany
| | - K Stoecker
- Bundeswehr Institute for Microbiology, Munich, Germany
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Francés-Monerris A, Hognon C, Douki T, Monari A. Photoinduced DNA Lesions in Dormant Bacteria: The Peculiar Route Leading to Spore Photoproducts Characterized by Multiscale Molecular Dynamics*. Chemistry 2020; 26:14236-14241. [PMID: 32597544 DOI: 10.1002/chem.202002484] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Indexed: 11/07/2022]
Abstract
Some bacterial species enter a dormant state in the form of spores to resist to unfavorable external conditions. Spores are resistant to a wide series of stress agents, including UV radiation, and can last for tens to hundreds of years. Due to the suspension of biological functions, such as DNA repair, they accumulate DNA damage upon exposure to UV radiation. Differently from active organisms, the most common DNA photoproducts in spores are not cyclobutane pyrimidine dimers, but rather the so-called spore photoproducts. This noncanonical photochemistry results from the dry state of DNA and its binding to small, acid-soluble proteins that drastically modify the structure and photoreactivity of the nucleic acid. Herein, multiscale molecular dynamics simulations, including extended classical molecular dynamics and quantum mechanics/molecular mechanics based dynamics, are used to elucidate the coupling of electronic and structural factors that lead to this photochemical outcome. In particular, the well-described impact of the peculiar DNA environment found in spores on the favored formation of the spore photoproduct, given the small free energy barrier found for this path, is rationalized. Meanwhile, the specific organization of spore DNA precludes the photochemical path that leads to cyclobutane pyrimidine dimer formation.
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Affiliation(s)
- Antonio Francés-Monerris
- Université de Lorraine and CNRS, LPCT UMR 7019, 54000, Nancy, France
- Departament de Química Física, Universitat de València, 46100, Burjassot, Spain
| | - Cécilia Hognon
- Université de Lorraine and CNRS, LPCT UMR 7019, 54000, Nancy, France
- Université de Lorraine and CNRS, CRAN UMR 7039, 54000, Nancy, France
| | - Thierry Douki
- SyMMES, CEA, CNRS, IRIG, University Grenoble Alpes, 38000, Grenoble, France
| | - Antonio Monari
- Université de Lorraine and CNRS, LPCT UMR 7019, 54000, Nancy, France
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Player JK, Despain JT, Robison RA. Correlations between available primary amines, endospore coat thickness, and alkaline glutaraldehyde sensitivity for spores of select Bacillus species. Microbiologyopen 2020; 9:e1117. [PMID: 32996289 PMCID: PMC7658453 DOI: 10.1002/mbo3.1117] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 08/12/2020] [Accepted: 08/18/2020] [Indexed: 11/13/2022] Open
Abstract
Alkaline glutaraldehyde (GTA) is a high‐level chemical disinfectant/sterilant and has a broad microbial kill spectrum. The precise antimicrobial mechanism of GTA remains debated. GTA kill times are extremely variable across different organisms, illustrating the need for a better understanding of GTA kill mechanisms related to different organisms. A commonly proposed GTA kill mechanism suggests that it works by cross‐linking accessible primary amines on important surface proteins. If true, the antimicrobial activity of GTA may directly correlate to the number of these available functional groups. Bacillus species form highly resistant bacterial endospores that are commonly used as one of the most stringent test organisms for disinfection and sterilization. In this study, we compared the log reduction times of alkaline GTA on spores from 4 Bacillus species to fluorescent profiles generated using Alexa Fluor™ amine‐reactive dyes. GTA kill times were also compared to mean spore coat thicknesses as measured with scanning electron microscopy (SEM). Fluorescence values generated from bound amine‐reactive dye showed a strong, positive correlation to GTA susceptibility, as measured by GTA 6‐log10 reduction times. Spore coat thickness also showed a strong, positive correlation to reduction time values. Results support the hypothesis that GTA kill times are directly related to the number of available primary amines on bacterial endospores. Results also indicated that the killing efficacy of GTA may be influenced by its ability to penetrate the spore coat to reach additional targets, suggesting that damaging important biomolecules beyond surface proteins may be involved in GTA killing mechanisms.
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Affiliation(s)
- Jacob Kent Player
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, USA
| | - Justen Thalmus Despain
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, USA
| | - Richard A Robison
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, USA
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Wambui J, Cernela N, Corti S, Stephan R. Comparative Genome Analysis and Phenotypic Characterization of Clostridium gasigenes CGAS001 Isolated From Chilled Vacuum-Packed Lamb Meat. Front Microbiol 2020; 11:2048. [PMID: 32983035 PMCID: PMC7476324 DOI: 10.3389/fmicb.2020.02048] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Accepted: 08/04/2020] [Indexed: 12/17/2022] Open
Abstract
Genomic data for psychrophilic bacteria causing blown pack spoilage (BPS) are limited. This study characterizes the genome of a novel Clostridium gasigenes strain CGAS001 isolated from meat juice sample (MJS) of vacuum-packed lamb meat by comparing it with the type strain C. gasigenes DSM 12272 and five strains representing four other BPS-causing Clostridium sensu stricto species. Phenotypic characteristics of the strain, which include biochemical characteristics, antimicrobial resistance and production of putative polyketide, have been determined. The size of its draft genome is 4.1 Mb with 3,845 coding sequences, 28.7% GC content and 95 RNA genes that include 75 tRNAs, 17 rRNAs, and 3 ncRNAs. Average Nucleotide Identity (ANI) and digital DNA-DNA Hybridization (dDDH) predict that C. gasigenes CGAS001 and DSM 12272 constitute a single species (ANI and dDDH = 98.3% for speciation) but two distinct subspecies (dDDH = 73.3% for subspeciation). The genome is characterized by saccharolytic, lipolytic and proteolytic genes as well as hemolysins and phospholipases, which are consistent with its phenotype. The genome also reveals the ability of C. gasigenes to synthesize polyketides which is demonstrated by the antimicrobial activity of a crude polyketide extract against Listeria monocytogenes and Enterococcus devriesei. The strain is resistant to polymyxin B and streptomycin. The genetic and phenotypic analyses suggest that CGAS001 constitutes a novel subspecies of C. gasigenes adapted to a saprophytic lifestyle and can synthesize narrow spectrum antimicrobial compounds.
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Affiliation(s)
- Joseph Wambui
- Institute for Food Safety and Hygiene, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Nicole Cernela
- Institute for Food Safety and Hygiene, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Sabrina Corti
- Institute for Food Safety and Hygiene, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Roger Stephan
- Institute for Food Safety and Hygiene, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
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Kang SJ, Jun JS, Moon JA, Hong KW. Surface display of p75, a Lactobacillus rhamnosus GG derived protein, on Bacillus subtilis spores and its antibacterial activity against Listeria monocytogenes. AMB Express 2020; 10:139. [PMID: 32770428 PMCID: PMC7415045 DOI: 10.1186/s13568-020-01073-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Accepted: 07/25/2020] [Indexed: 01/05/2023] Open
Abstract
Lactobacillus rhamnosus p75 protein with peptidoglycan hydrolase (PGH) activity is one of the key molecules exhibiting anti-apoptotic and cell-protective activity for human intestinal epithelial cells. In this study, with the goal of developing new probiotics, the p75 protein was displayed on the surface of Bacillus subtilis spores using spore coat protein CotG as an anchoring motif. The PGH activity, stability, and the antibacterial activity of the spore-displayed p75 (CotG-p75) protein were also investigated. The PGH activity of the CotG-p75 against peptidoglycan extracted from B. subtilis was confirmed by the ninhydrin test. Under various harsh conditions, compared to the control groups, the PGH activities of CotG-p75 were very stable in the range of pH 3–7 and maintained at 70% at 50 °C. In addition, the antibacterial activity of CotG-p75 against Listeria monocytogenes was evaluated by a time-kill assay. After 6 h incubation in phosphate-buffered saline, CotG-p75 reduced the number of viable cells of L. monocytogenes by up to 2.0 log. Scanning electron microscopy analysis showed that the cell wall of L. monocytogenes was partially damaged by the treatment with CotG-p75. Our preliminary results show that CotG-p75 could be a good candidate for further research to develop new genetically engineered probiotics.
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68
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Xiang M, Kang Q, Zhang D. Advances on systems metabolic engineering of Bacillus subtilis as a chassis cell. Synth Syst Biotechnol 2020; 5:245-251. [PMID: 32775709 PMCID: PMC7394859 DOI: 10.1016/j.synbio.2020.07.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 07/22/2020] [Accepted: 07/23/2020] [Indexed: 12/15/2022] Open
Abstract
The Gram-positive model bacterium Bacillus subtilis, has been broadly applied in various fields because of its low pathogenicity and strong protein secretion ability, as well as its well-developed fermentation technology. B. subtilis is considered as an attractive host in the field of metabolic engineering, in particular for protein expression and secretion, so it has been well studied and applied in genetic engineering. In this review, we discussed why B. subtilis is a good chassis cell for metabolic engineering. We also summarized the latest research progress in systematic biology, synthetic biology and evolution-based engineering of B. subtilis, and showed systemic metabolic engineering expedite the harnessing B. subtilis for bioproduction.
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Affiliation(s)
- Mengjie Xiang
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, People's Republic of China.,Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, People's Republic of China.,University of Chinese Academy of Sciences, Beijing, 100049, People's Republic of China
| | - Qian Kang
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, People's Republic of China.,Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, People's Republic of China.,University of Chinese Academy of Sciences, Beijing, 100049, People's Republic of China
| | - Dawei Zhang
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, People's Republic of China.,Key Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, People's Republic of China.,University of Chinese Academy of Sciences, Beijing, 100049, People's Republic of China
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69
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Hu Z, Liu H, Zhang H, Zhang X, Zhou M, Lou L, Zheng P, Xi C, Hu B. Temporal discrepancy of airborne total bacteria and pathogenic bacteria between day and night. ENVIRONMENTAL RESEARCH 2020; 186:109540. [PMID: 32339956 DOI: 10.1016/j.envres.2020.109540] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Revised: 04/14/2020] [Accepted: 04/14/2020] [Indexed: 06/11/2023]
Abstract
As the most abundant microbes in the atmosphere, airborne bacteria are closely involved in affecting human health, regional climate and ecological balance. The mobility of airborne microorganisms makes it necessary to study the community dynamic in short cycle. Nevertheless, it remains obscure how the airborne bacteria especially the pathogenic bacteria vary on the small time scale of day and night. To investigate the nycterohemeral discrepancy of airborne total bacteria and pathogenic bacteria, PM2.5 samples were collected in Hangzhou between day and night. Microbial taxonomic information was obtained through 16S rRNA gene sequencing and "human pathogens database" screening. Further analyses based on Multiple Regression Matrices (MRM) approach and Concentration Weighted Trajectory (CWT) model were conducted to elucidate the effect of local environmental factors and long-range transport. The community composition of total bacteria tended to be similar in the daytime while pathogenic bacteria turned out to be homogeneous in the nighttime. To be vigilant, the diversity of airborne pathogenic bacteria echoed the frequency of anthropogenic activities with the pathogen inhalation rate roughly at 428 copies/h and 235 copies/h respectively in daytime and nighttime. The nycterohemeral discrepancy of total bacteria was principally driven by the filtering of environmental factors, i.e., CO and NO2, indicating that anthropogenic activities brought about the homogeneity. Airborne pathogenic bacteria coupled with the strong resistances of environmental filtering stood out from their non-pathogenic counterpart, which enabled the long-range transport. Indeed, the nycterohemeral discrepancy of pathogenic bacteria was shaped by the transport of air masses. This research filled the gaps in temporal variance of airborne microorganisms on the small time scale of day and night, providing crucial foundation for precisely predicting ecological and health effects of bioaerosols.
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Affiliation(s)
- Zhichao Hu
- Department of Environmental Engineering, Zhejiang University, Hangzhou, 310058, China
| | - Huan Liu
- Department of Environmental Engineering, Zhejiang University, Hangzhou, 310058, China
| | - Hao Zhang
- Department of Environmental Engineering, Zhejiang University, Hangzhou, 310058, China
| | - Xu Zhang
- Department of Environmental Engineering, Zhejiang University, Hangzhou, 310058, China
| | - Meng Zhou
- Department of Environmental Engineering, Zhejiang University, Hangzhou, 310058, China
| | - Liping Lou
- Department of Environmental Engineering, Zhejiang University, Hangzhou, 310058, China
| | - Ping Zheng
- Department of Environmental Engineering, Zhejiang University, Hangzhou, 310058, China
| | - Chuanwu Xi
- Department of Environmental Health Sciences, School of Public Health, University of Michigan, Ann Arbor, MI, USA.
| | - Baolan Hu
- Department of Environmental Engineering, Zhejiang University, Hangzhou, 310058, China; Research Center for Air Pollution and Health, Zhejiang University, Hangzhou, 310058, China; Key Laboratory of Environment Remediation and Ecological Health, Ministry of Education, College of Environmental Resource Sciences, Zhejiang University, Hangzhou, 310058, China.
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Stier P, Kulozik U. Effect of Sporulation Conditions Following Submerged Cultivation on the Resistance of Bacillus atrophaeus Spores against Inactivation by H 2O 2. Molecules 2020; 25:molecules25132985. [PMID: 32629775 PMCID: PMC7412142 DOI: 10.3390/molecules25132985] [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: 05/27/2020] [Revised: 06/16/2020] [Accepted: 06/29/2020] [Indexed: 12/02/2022] Open
Abstract
The resistance formation of spores in general and of Bacillus atrophaeus in particular has long been the focus of science in the bio-defense, pharmaceutical and food industries. In the food industry, it is used as a biological indicator (BI) for the evaluation of the inactivation effects of hydrogen peroxide in processing and end packaging lines’ sterilization. Defined BI resistances are critical to avoid false positive and negative tests, which are salient problems due to the variable resistance of currently available commercial BIs. Although spores for use as BIs have been produced for years, little is known about the influence of sporulation conditions on the resistance as a potential source of random variability. This study therefore examines the dependence of spore resistance on the temperature, pH and partial oxygen saturation during submerged production in a bioreactor. For this purpose, spores were produced under different sporulation conditions and their resistance, defined by the D-value, was determined using a count reduction test in tempered 35% liquid hydrogen peroxide. The statistical analysis of the test results shows a quadratic dependence of the resistance on the pH, with the highest D-values at neutral pH. The sporulation temperature has a linear influence on the resistance. The higher the temperature, the higher the D-value. However, these factors interact with each other, which means that the temperature only influences the resistance when the pH is within a certain range. The oxygen partial pressure during sporulation has no significant influence. Based on the data obtained, a model could be developed enabling the resistance of BIs to be calculated, predicted and standardized depending on the sporulation conditions. BI manufacturers could thus produce BIs with defined resistances for the validation of sterilization effects in aseptic packaging/filling lines for the reliable manufacture of shelf-stable and safe food products.
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71
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Brivio MF, Mastore M. When Appearance Misleads: The Role of the Entomopathogen Surface in the Relationship with Its Host. INSECTS 2020; 11:E387. [PMID: 32585858 PMCID: PMC7348879 DOI: 10.3390/insects11060387] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 06/18/2020] [Accepted: 06/20/2020] [Indexed: 12/14/2022]
Abstract
Currently, potentially harmful insects are controlled mainly by chemical synthetic insecticides, but environmental emergencies strongly require less invasive control techniques. The use of biological insecticides in the form of entomopathogenic organisms is undoubtedly a fundamental resource for the biological control of insect pests in the future. These infectious agents and endogenous parasites generally act by profoundly altering the host's physiology to death, but their success is closely related to the neutralization of the target insect's immune response. In general, entomopathogen parasites, entomopathogenic bacteria, and fungi can counteract immune processes through the effects of secretion/excretion products that interfere with and damage the cells and molecules typical of innate immunity. However, these effects are observed in the later stages of infection, whereas the risk of being recognized and neutralized occurs very early after penetration and involves the pathogen surface components and molecular architecture; therefore, their role becomes crucial, particularly in the earliest pathogenesis. In this review, we analyze the evasion/interference strategies that entomopathogens such as the bacterium Bacillus thuringiensis, fungi, nematocomplexes, and wasps implement in the initial stages of infection, i.e., the phases during which body or cell surfaces play a key role in the interaction with the host receptors responsible for the immunological discrimination between self and non-self. In this regard, these organisms demonstrate evasive abilities ascribed to their body surface and cell wall; it appears that the key process of these mechanisms is the capability to modify the surface, converting it into an immunocompatible structure, or interaction that is more or less specific to host factors.
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Affiliation(s)
- Maurizio Francesco Brivio
- Laboratory of Comparative Immunology and Parasitology, Department of Theoretical and Applied Sciences, University of Insubria, 21100 Varese, Italy;
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The molecular dynamics of bacterial spore and the role of calcium dipicolinate in core properties at the sub-nanosecond time-scale. Sci Rep 2020; 10:8265. [PMID: 32427943 PMCID: PMC7237433 DOI: 10.1038/s41598-020-65093-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 04/21/2020] [Indexed: 11/18/2022] Open
Abstract
Bacterial spores are among the most resistant forms of life on Earth. Their exceptional resistance properties rely on various strategies, among them the core singular structure, organization and hydration. By using elastic incoherent neutron scattering, we probed the dynamics of Bacillus subtilis spores to determine whether core macromolecular motions at the sub-nanosecond timescale could also contribute to their resistance to physical stresses. In addition, in order to better specify the role of the various spore components, we used different mutants lacking essential structure such as the coat (PS4150 mutant), or the calcium dipicolinic acid complex (CaDPA) located in the core (FB122 mutant). PS4150 allows to better probe the core’s dynamics, as proteins of the coat represent an important part of spore proteins, and FB122 gives information about the role of the large CaDPA depot for the mobility of core’s components. We show that core’s macromolecular mobility is not particularly constrained at the sub-nanosecond timescale in spite of its low water content as some dynamical characteristics as force constants are very close to those of vegetative bacteria such as Escherichia coli or to those of fully hydrated proteins. Although the force constants of the coatless mutant are similar to the wild-type’s ones, it has lower mean square displacements (MSDs) at high Q showing that core macromolecules are somewhat more constrained than the rest of spore components. However, no behavior reflecting the glassy state regularly evoked in the literature could be drawn from our data. As hydration and macromolecules’ mobility are highly correlated, the previous assumption, that core low water content might explain spores’ exceptional resistance properties seems unlikely. Thus, we confirm recent theories, suggesting that core water is mostly as free as bulk water and proteins/macromolecules are fully hydrated. The germination of spores leads to a much less stable system with a force constant of 0.1 N/m and MSDs ~2.5 times higher at low Q than in the dormant state. DPA has also an influence on core mobility with a slightly lower force constant for the DPA-less mutant than for the wild-type, and MSDs that are ~ 1.8 times higher on average than for the wild-type at low Q. At high Q, germinated and DPA-less spores were very similar to the wild-type ones, showing that DPA and core compact structure might influence large amplitude motions rather than local dynamics of macromolecules.
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Feizollahi E, Misra NN, Roopesh MS. Factors influencing the antimicrobial efficacy of Dielectric Barrier Discharge (DBD) Atmospheric Cold Plasma (ACP) in food processing applications. Crit Rev Food Sci Nutr 2020; 61:666-689. [PMID: 32208859 DOI: 10.1080/10408398.2020.1743967] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Atmospheric cold plasma (ACP) is an emerging technology in the food industry with a huge antimicrobial potential to improve safety and extend the shelf life of food products. Dielectric barrier discharge (DBD) is a popular approach for generating ACP. Thanks to the numerous advantages of DBD ACP, it is proving to be successful in a number of applications, including microbial decontamination of foods. The antimicrobial efficacy of DBD ACP is influenced by multiple factors. This review presents an overview of ACP sources, with an emphasis on DBD, and an analysis of their antimicrobial efficacy in foods in open atmosphere and in-package modes. Specifically, the influence of process, product, and microbiological factors influencing the antimicrobial efficacy of DBD ACP are critically reviewed. DBD ACP is a promising technology that can improve food safety with minimal impact on food quality under optimal conditions. Once the issues pertinent to scale-up of plasma sources are appropriately addressed, the DBD ACP technology will find wider adaptation in food industry.
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Affiliation(s)
- Ehsan Feizollahi
- Department of Agricultural, Food & Nutritional Science, University of Alberta, Edmonton, Canada
| | - N N Misra
- Department of Engineering, Faculty of Agriculture, Dalhousie University, Halifax, NS, Canada
| | - M S Roopesh
- Department of Agricultural, Food & Nutritional Science, University of Alberta, Edmonton, Canada
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Reineke K, Mathys A. Endospore Inactivation by Emerging Technologies: A Review of Target Structures and Inactivation Mechanisms. Annu Rev Food Sci Technol 2020; 11:255-274. [DOI: 10.1146/annurev-food-032519-051632] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Recent developments in preservation technologies allow for the delivery of food with nutritional value and superior taste. Of special interest are low-acid, shelf-stable foods in which the complete control or inactivation of bacterial endospores is the crucial step to ensure consumer safety. Relevant preservation methods can be classified into physicochemical or physical hurdles, and the latter can be subclassified into thermal and nonthermal processes. The underlying inactivation mechanisms for each of these physicochemical or physical processes impact different morphological or molecular structures essential for spore germination and integrity in the dormant state. This review provides an overview of distinct endospore defense mechanisms that affect emerging physical hurdles as well as which technologies address these mechanisms. The physical spore-inactivation technologies considered include thermal, dynamic, and isostatic high pressure and electromagnetic technologies, such as pulsed electric fields, UV light, cold atmospheric pressure plasma, and high- or low-energy electron beam.
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Affiliation(s)
| | - Alexander Mathys
- Sustainable Food Processing Laboratory, Department of Health Science and Technology, ETH Zurich, CH-8092 Zurich, Switzerland
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Lv R, Muhammad AI, Zou M, Yu Y, Fan L, Zhou J, Ding T, Ye X, Guo M, Liu D. Hurdle enhancement of acidic electrolyzed water antimicrobial efficacy on Bacillus cereus spores using ultrasonication. Appl Microbiol Biotechnol 2020; 104:4505-4513. [PMID: 32215708 DOI: 10.1007/s00253-020-10393-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 12/30/2019] [Accepted: 01/19/2020] [Indexed: 12/20/2022]
Abstract
This study evaluated the inactivation effect of ultrasonic treatment combined with acidic electrolyzed water (AEW) on Bacillus cereus spores. AEW treatment reduced the spores by 1.05-1.37 log CFU/mL while the sporicidal effect of ultrasound was minor. More strikingly, simultaneous ultrasonic and AEW treatments for 30 min led to 2.29 log CFU/mL reduction and thus, considered a synergistic effect. Flow cytometry combined with SYTO/PI staining analysis revealed that ultrasound hydrolyzed the cortex while the AEW partially damaged the integrity of the inner membrane. Scanning and transmission electron microscopies were used to characterize the ultrastructural changes. The detachment of the exosporium induced by ultrasound was the most apparent difference compared with the control group, and the electron density of spores appeared to be heterogeneous after treatment with AEW. These results indicated that combining ultrasound with AEW is a promising decontamination technology with potential uses in the food industry and environmental remediation.
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Affiliation(s)
- Ruiling Lv
- College of Biosystems Engineering and Food Science, National-Local Joint Engineering Laboratory of Intelligent Food Technology and Equipment, Zhejiang Key Laboratory for Agro-Food Processing, Zhejiang R & D Center for Food Technology and Equipment, Zhejiang University, Hangzhou, 310058, China
| | - Aliyu Idris Muhammad
- College of Biosystems Engineering and Food Science, National-Local Joint Engineering Laboratory of Intelligent Food Technology and Equipment, Zhejiang Key Laboratory for Agro-Food Processing, Zhejiang R & D Center for Food Technology and Equipment, Zhejiang University, Hangzhou, 310058, China
- Department of Agricultural and Environmental Engineering, Faculty of Engineering, Bayero University, Kano, Nigeria
| | - Mingming Zou
- College of Biosystems Engineering and Food Science, National-Local Joint Engineering Laboratory of Intelligent Food Technology and Equipment, Zhejiang Key Laboratory for Agro-Food Processing, Zhejiang R & D Center for Food Technology and Equipment, Zhejiang University, Hangzhou, 310058, China
| | - Yue Yu
- College of Biosystems Engineering and Food Science, National-Local Joint Engineering Laboratory of Intelligent Food Technology and Equipment, Zhejiang Key Laboratory for Agro-Food Processing, Zhejiang R & D Center for Food Technology and Equipment, Zhejiang University, Hangzhou, 310058, China
| | - Lihua Fan
- College of Biosystems Engineering and Food Science, National-Local Joint Engineering Laboratory of Intelligent Food Technology and Equipment, Zhejiang Key Laboratory for Agro-Food Processing, Zhejiang R & D Center for Food Technology and Equipment, Zhejiang University, Hangzhou, 310058, China
| | - Jianwei Zhou
- College of Biosystems Engineering and Food Science, National-Local Joint Engineering Laboratory of Intelligent Food Technology and Equipment, Zhejiang Key Laboratory for Agro-Food Processing, Zhejiang R & D Center for Food Technology and Equipment, Zhejiang University, Hangzhou, 310058, China
- Ningbo Institute of Technology, Zhejiang University, Ningbo, 315100, China
| | - Tian Ding
- College of Biosystems Engineering and Food Science, National-Local Joint Engineering Laboratory of Intelligent Food Technology and Equipment, Zhejiang Key Laboratory for Agro-Food Processing, Zhejiang R & D Center for Food Technology and Equipment, Zhejiang University, Hangzhou, 310058, China
| | - Xingqian Ye
- College of Biosystems Engineering and Food Science, National-Local Joint Engineering Laboratory of Intelligent Food Technology and Equipment, Zhejiang Key Laboratory for Agro-Food Processing, Zhejiang R & D Center for Food Technology and Equipment, Zhejiang University, Hangzhou, 310058, China
| | - Mingming Guo
- College of Biosystems Engineering and Food Science, National-Local Joint Engineering Laboratory of Intelligent Food Technology and Equipment, Zhejiang Key Laboratory for Agro-Food Processing, Zhejiang R & D Center for Food Technology and Equipment, Zhejiang University, Hangzhou, 310058, China
| | - Donghong Liu
- College of Biosystems Engineering and Food Science, National-Local Joint Engineering Laboratory of Intelligent Food Technology and Equipment, Zhejiang Key Laboratory for Agro-Food Processing, Zhejiang R & D Center for Food Technology and Equipment, Zhejiang University, Hangzhou, 310058, China.
- Ningbo Institute of Technology, Zhejiang University, Ningbo, 315100, China.
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Aistleitner K, Sieper T, Stürz I, Jeske R, Tritscheller S, Mantel S, Tscherne A, Zange S, Stoecker K, Wölfel R. NOTIFy (non-toxic lyophilized field)-FISH for the identification of biological agents by Fluorescence in situ Hybridization. PLoS One 2020; 15:e0230057. [PMID: 32142548 PMCID: PMC7059943 DOI: 10.1371/journal.pone.0230057] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 02/20/2020] [Indexed: 12/02/2022] Open
Abstract
The rapid and reliable diagnostics of highly pathogenic bacteria under restricted field conditions poses one of the major challenges to medical biodefense, especially since false positive or false negative reports might have far-reaching consequences. Fluorescence in situ hybridization (FISH) has the potential to represent a powerful microscopy-based addition to the existing molecular-based diagnostic toolbox. In this study, we developed a set of FISH-probes for the fast, matrix independent and simultaneous detection of thirteen highly pathogenic bacteria in different environmental and clinical sample matrices. Furthermore, we substituted formamide, a routinely used chemical that is toxic and volatile, by non-toxic urea. This will facilitate the application of FISH under resource limited field laboratory conditions. We demonstrate that hybridizations performed with urea show the same specificity and comparable signal intensities for the FISH-probes used in this study. To further simplify the use of FISH in the field, we lyophilized the reagents needed for FISH. The signal intensities obtained with these lyophilized reagents are comparable to freshly prepared reagents even after storage for a month at room temperature. Finally, we show that by the use of non-toxic lyophilized field (NOTIFy)-FISH, specific detection of microorganisms with simple and easily transportable equipment is possible in the field.
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Affiliation(s)
| | - Tina Sieper
- Bundeswehr Institute of Microbiology, Munich, Germany
| | - Inga Stürz
- Bundeswehr Institute of Microbiology, Munich, Germany
| | - Rimma Jeske
- Bundeswehr Institute of Microbiology, Munich, Germany
| | | | - Sonja Mantel
- Bundeswehr Institute of Microbiology, Munich, Germany
| | | | - Sabine Zange
- Bundeswehr Institute of Microbiology, Munich, Germany
| | - Kilian Stoecker
- Bundeswehr Institute of Microbiology, Munich, Germany
- * E-mail:
| | - Roman Wölfel
- Bundeswehr Institute of Microbiology, Munich, Germany
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Amon JD, Yadav AK, Ramirez-Guadiana FH, Meeske AJ, Cava F, Rudner DZ. SwsB and SafA Are Required for CwlJ-Dependent Spore Germination in Bacillus subtilis. J Bacteriol 2020; 202:e00668-19. [PMID: 31871031 PMCID: PMC7043669 DOI: 10.1128/jb.00668-19] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 12/13/2019] [Indexed: 02/07/2023] Open
Abstract
When Bacillus subtilis spores detect nutrients, they exit dormancy through the processes of germination and outgrowth. A key step in germination is the activation of two functionally redundant cell wall hydrolases (SleB and CwlJ) that degrade the specialized cortex peptidoglycan that surrounds the spore. How these enzymes are regulated remains poorly understood. To identify additional factors that affect their activity, we used transposon sequencing to screen for synthetic germination defects in spores lacking SleB or CwlJ. Other than the previously characterized protein YpeB, no additional factors were found to be specifically required for SleB activity. In contrast, our screen identified SafA and YlxY (renamed SwsB) in addition to the known factors GerQ and CotE as proteins required for CwlJ function. SafA is a member of the spore's proteinaceous coat and we show that, like GerQ and CotE, it is required for accumulation and retention of CwlJ in the dormant spore. SwsB is broadly conserved among spore formers, and we show that it is required for CwlJ to efficiently degrade the cortex during germination. Intriguingly, SwsB resembles polysaccharide deacetylases, and its putative catalytic residues are required for its role in germination. However, we find no chemical signature of its activity on the spore cortex or in vitro While the precise, mechanistic role of SwsB remains unknown, we explore and discuss potential activities.IMPORTANCE Spore formation in Bacillus subtilis has been studied for over half a century, and virtually every step in this developmental process has been characterized in molecular detail. In contrast, how spores exit dormancy remains less well understood. A key step in germination is the degradation of the specialized cell wall surrounding the spore called the cortex. Two enzymes (SleB and CwlJ) specifically target this protective layer, but how they are regulated and whether additional factors promote their activity are unknown. Here, we identified the coat protein SafA and a conserved but uncharacterized protein YlxY as additional factors required for CwlJ-dependent degradation of the cortex. Our analysis provides a more complete picture of this essential step in the exit from dormancy.
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Affiliation(s)
- Jeremy D Amon
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Akhilesh K Yadav
- Laboratory for Molecular Infection Medicine, Department of Molecular Biology, Umeå University, Umeå, Sweden
- Analytical Chemistry Division, CSIR-Indian Institute of Toxicology Research, Lucknow, India
| | | | - Alexander J Meeske
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Felipe Cava
- Laboratory for Molecular Infection Medicine, Department of Molecular Biology, Umeå University, Umeå, Sweden
| | - David Z Rudner
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts, USA
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Ramos-Silva P, Serrano M, Henriques AO. From Root to Tips: Sporulation Evolution and Specialization in Bacillus subtilis and the Intestinal Pathogen Clostridioides difficile. Mol Biol Evol 2020; 36:2714-2736. [PMID: 31350897 PMCID: PMC6878958 DOI: 10.1093/molbev/msz175] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Bacteria of the Firmicutes phylum are able to enter a developmental pathway that culminates with the formation of highly resistant, dormant endospores. Endospores allow environmental persistence, dissemination and for pathogens, are also infection vehicles. In both the model Bacillus subtilis, an aerobic organism, and in the intestinal pathogen Clostridioides difficile, an obligate anaerobe, sporulation mobilizes hundreds of genes. Their expression is coordinated between the forespore and the mother cell, the two cells that participate in the process, and is kept in close register with the course of morphogenesis. The evolutionary mechanisms by which sporulation emerged and evolved in these two species, and more broadly across Firmicutes, remain largely unknown. Here, we trace the origin and evolution of sporulation using the genes known to be involved in the process in B. subtilis and C. difficile, and estimating their gain-loss dynamics in a comprehensive bacterial macroevolutionary framework. We show that sporulation evolution was driven by two major gene gain events, the first at the base of the Firmicutes and the second at the base of the B. subtilis group and within the Peptostreptococcaceae family, which includes C. difficile. We also show that early and late sporulation regulons have been coevolving and that sporulation genes entail greater innovation in B. subtilis with many Bacilli lineage-restricted genes. In contrast, C. difficile more often recruits new sporulation genes by horizontal gene transfer, which reflects both its highly mobile genome, the complexity of the gut microbiota, and an adjustment of sporulation to the gut ecosystem.
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Affiliation(s)
- Paula Ramos-Silva
- Instituto Gulbenkian de Ciência, Oeiras, Portugal.,Marine Biodiversity Group, Naturalis Biodiversity Center, Leiden, The Netherlands
| | - Mónica Serrano
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Adriano O Henriques
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
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79
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Progress in research and application development of surface display technology using Bacillus subtilis spores. Appl Microbiol Biotechnol 2020; 104:2319-2331. [PMID: 31989224 PMCID: PMC7223921 DOI: 10.1007/s00253-020-10348-x] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 12/16/2019] [Accepted: 01/03/2020] [Indexed: 02/02/2023]
Abstract
Bacillus subtilis is a widely distributed aerobic Gram-positive species of bacteria. As a tool in the lab, it has the advantages of nonpathogenicity and limited likelihood of becoming drug resistant. It is a probiotic strain that can be directly used in humans and animals. It can be induced to produce spores under nutrient deficiency or other adverse conditions. B. subtilis spores have unique physical, chemical, and biochemical characteristics. Expression of heterologous antigens or proteins on the surface of B. subtilis spores has been successfully performed for over a decade. As an update and supplement to previously published research, this paper reviews the latest research on spore surface display technology using B. subtilis. We have mainly focused on the regulation of spore coat protein expression, display and application of exogenous proteins, and identification of developing research areas of spore surface display technology.
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Lv R, Zou M, Chen W, Zhou J, Ding T, Ye X, Liu D. Ultrasound: Enhance the detachment of exosporium and decrease the hydrophobicity of Bacillus cereus spores. Lebensm Wiss Technol 2019. [DOI: 10.1016/j.lwt.2019.108473] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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81
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Isticato R, Lanzilli M, Petrillo C, Donadio G, Baccigalupi L, Ricca E. Bacillus subtilisbuilds structurally and functionally different spores in response to the temperature of growth. Environ Microbiol 2019; 22:170-182. [DOI: 10.1111/1462-2920.14835] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 10/16/2019] [Accepted: 10/17/2019] [Indexed: 11/29/2022]
Affiliation(s)
- Rachele Isticato
- Department of BiologyFederico II University of Naples, Complesso Universitario di Monte Sant'Angelo, Via Cinthia 80126 Naples Italy
| | - Mariamichela Lanzilli
- Department of BiologyFederico II University of Naples, Complesso Universitario di Monte Sant'Angelo, Via Cinthia 80126 Naples Italy
| | - Claudia Petrillo
- Department of BiologyFederico II University of Naples, Complesso Universitario di Monte Sant'Angelo, Via Cinthia 80126 Naples Italy
| | - Giuliana Donadio
- Department of BiologyFederico II University of Naples, Complesso Universitario di Monte Sant'Angelo, Via Cinthia 80126 Naples Italy
| | - Loredana Baccigalupi
- Department of Molecular Medicine and Medical BiotechnologyFederico II University of Naples, Complesso Universitario di Monte Sant'Angelo, Via Cinthia 80126 Naples Italy
| | - Ezio Ricca
- Department of BiologyFederico II University of Naples, Complesso Universitario di Monte Sant'Angelo, Via Cinthia 80126 Naples Italy
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82
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Shen A, Edwards AN, Sarker MR, Paredes-Sabja D. Sporulation and Germination in Clostridial Pathogens. Microbiol Spectr 2019; 7:10.1128/microbiolspec.GPP3-0017-2018. [PMID: 31858953 PMCID: PMC6927485 DOI: 10.1128/microbiolspec.gpp3-0017-2018] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Indexed: 12/14/2022] Open
Abstract
As obligate anaerobes, clostridial pathogens depend on their metabolically dormant, oxygen-tolerant spore form to transmit disease. However, the molecular mechanisms by which those spores germinate to initiate infection and then form new spores to transmit infection remain poorly understood. While sporulation and germination have been well characterized in Bacillus subtilis and Bacillus anthracis, striking differences in the regulation of these processes have been observed between the bacilli and the clostridia, with even some conserved proteins exhibiting differences in their requirements and functions. Here, we review our current understanding of how clostridial pathogens, specifically Clostridium perfringens, Clostridium botulinum, and Clostridioides difficile, induce sporulation in response to environmental cues, assemble resistant spores, and germinate metabolically dormant spores in response to environmental cues. We also discuss the direct relationship between toxin production and spore formation in these pathogens.
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Affiliation(s)
- Aimee Shen
- Department of Molecular Biology and Microbiology, Tufts University Medical School, Boston, MA
| | - Adrianne N Edwards
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, GA
| | - Mahfuzur R Sarker
- Department of Microbiology, College of Science, Oregon State University, Corvallis, OR
- Department of Biomedical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR
| | - Daniel Paredes-Sabja
- Department of Gut Microbiota and Clostridia Research Group, Departamento de Ciencias Biolo gicas, Facultad de Ciencias Biologicas, Universidad Andres Bello, Santiago, Chile
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83
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A 2-dimensional ratchet model describes assembly initiation of a specialized bacterial cell surface. Proc Natl Acad Sci U S A 2019; 116:21789-21799. [PMID: 31597735 DOI: 10.1073/pnas.1907397116] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Bacterial spores are dormant cells that are encased in a thick protein shell, the "coat," which participates in protecting the organism's DNA from environmental insults. The coat is composed of dozens of proteins that assemble in an orchestrated fashion during sporulation. In Bacillus subtilis, 2 proteins initiate coat assembly: SpoVM, which preferentially binds to micron-scale convex membranes and marks the surface of the developing spore as the site for coat assembly; and SpoIVA, a structural protein recruited by SpoVM that uses ATP hydrolysis to drive its irreversible polymerization around the developing spore. Here, we describe the initiation of coat assembly by SpoVM and SpoIVA. Using single-molecule fluorescence microscopy in vivo in sporulating cells and in vitro on synthetic spores, we report that SpoVM's localization is primarily driven by a lower off-rate on membranes of preferred curvature in the absence of other coat proteins. Recruitment and polymerization of SpoIVA results in the entrapment of SpoVM on the forespore surface. Using experimentally derived reaction parameters, we show that a 2-dimensional ratchet model can describe the interdependent localization dynamics of SpoVM and SpoIVA, wherein SpoVM displays a longer residence time on the forespore surface, which favors recruitment of SpoIVA to that location. Localized SpoIVA polymerization in turn prevents further sampling of other membranes by prelocalized SpoVM molecules. Our model therefore describes the dynamics of structural proteins as they localize and assemble at the correct place and time within a cell to form a supramolecular complex.
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84
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Karauzum H, Updegrove TB, Kong M, Wu IL, Datta SK, Ramamurthi KS. Vaccine display on artificial bacterial spores enhances protective efficacy against Staphylococcus aureus infection. FEMS Microbiol Lett 2019; 365:5061626. [PMID: 30084923 DOI: 10.1093/femsle/fny190] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 07/27/2018] [Indexed: 12/20/2022] Open
Abstract
Spores of Bacillus subtilis are encased in a protein coat composed of ∼80 different proteins. Recently, we reconstituted the basement layer of the coat, composed of two structural proteins (SpoVM and SpoIVA) around spore-sized silica beads encased in a lipid bilayer, to create synthetic spore-like particles termed 'SSHELs'. We demonstrated that SSHELs could display thousands of copies of proteins and small molecules of interest covalently linked to SpoIVA. In this study, we investigated the efficacy of SSHELs in delivering vaccines. We show that intramuscular vaccination of mice with undecorated one micron-diameter SSHELs elicited an antibody response against SpoIVA. We further demonstrate that SSHELs covalently modified with a catalytically inactivated staphylococcal alpha toxin variant (HlaH35L), without an adjuvant, resulted in improved protection against Staphylococcus aureus infection in a bacteremia model as compared to vaccination with the antigen alone. Although vaccination with either HlaH35L or HlaH35L conjugated to SSHELs similarly elicited the production of neutralizing antibodies to Hla, we found that a subset of memory T cells was differentially activated when the antigen was delivered on SSHELs. We propose that the particulate nature of SSHELs elicits a more robust immune response to the vaccine that results in superior protection against subsequent S. aureus infection.
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Affiliation(s)
- Hatice Karauzum
- Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA
| | - Taylor B Updegrove
- Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, 37 Convent Drive, Bethesda, MD 20892, USA
| | - Minsuk Kong
- Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, 37 Convent Drive, Bethesda, MD 20892, USA
| | - I-Lin Wu
- Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, 37 Convent Drive, Bethesda, MD 20892, USA
| | - Sandip K Datta
- Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA
| | - Kumaran S Ramamurthi
- Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, 37 Convent Drive, Bethesda, MD 20892, USA
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Aronson A. Regulation of expression of a select group of Bacillus anthracis spore coat proteins. FEMS Microbiol Lett 2019; 365:4942285. [PMID: 29562329 DOI: 10.1093/femsle/fny063] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Accepted: 03/16/2018] [Indexed: 12/30/2022] Open
Abstract
The spore coat of Bacilli is a relatively complex structure comprised of about 70 species of proteins in 2 or 3 layers. While some are involved in assembly or protection, the regulation of many are not well defined so lacZ transcriptional fusions were constructed to six Bacillus anthracis spore coat genes in order to gain insight into their possible functions. The genes were selected on the basis of the location of the encoded proteins within the coat and distribution among spore forming species. Conditions tested were temperature and media either as solid or liquid. The most extensive differences were for the relatively well expressed fusions to the cotH and cotM genes, which were greatest at 30°C on plates of a nutrient rich medium. The cotJ operon was moderately expressed under all conditions although somewhat higher on enriched plates at 30°C. Cot S was low under all conditions except for a substantial increase in biofilm medium. Cot∝ and cotF were essentially invariant with a somewhat greater expression in the more enriched medium. The capacity of a subset of coat genes to respond to various conditions reflects a flexibility in spore coat structure that may be necessary for adaptation to environmental challenges. This could account, at least in part, for the complexity of this structure.
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Affiliation(s)
- Arthur Aronson
- Department of Biological Sciences, Purdue University, 915 W. State St, West Lafayette 47907, USA
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86
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Expansion of the Spore Surface Polysaccharide Layer in Bacillus subtilis by Deletion of Genes Encoding Glycosyltransferases and Glucose Modification Enzymes. J Bacteriol 2019; 201:JB.00321-19. [PMID: 31235516 DOI: 10.1128/jb.00321-19] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Accepted: 06/18/2019] [Indexed: 12/16/2022] Open
Abstract
Polysaccharides (PS) decorate the surface of dormant endospores (spores). In the model organism for sporulation, Bacillus subtilis, the composition of the spore PS is not known in detail. Here, we have assessed how PS synthesis enzymes produced during the late stages of sporulation affect spore surface properties. Using four methods, bacterial adhesion to hydrocarbons (BATH) assays, India ink staining, transmission electron microscopy (TEM) with ruthenium red staining, and scanning electron microscopy (SEM), we characterized the contributions of four sporulation gene clusters, spsABCDEFGHIJKL, yfnHGF-yfnED, ytdA-ytcABC, and cgeAB-cgeCDE, on the morphology and properties of the crust, the outermost spore layer. Our results show that all mutations in the sps operon result in the production of spores that are more hydrophobic and lack a visible crust, presumably because of reduced PS deposition, while mutations in cgeD and the yfnH-D cluster noticeably expand the PS layer. In addition, yfnH-D mutant spores exhibit a crust with an unusual weblike morphology. The hydrophobic phenotype from sps mutant spores was partially rescued by a second mutation inactivating any gene in the yfnHGF operon. While spsI, yfnH, and ytdA are paralogous genes, all encoding glucose-1-phosphate nucleotidyltransferases, each paralog appears to contribute in a distinct manner to the spore PS. Our data are consistent with the possibility that each gene cluster is responsible for the production of its own respective deoxyhexose. In summary, we found that disruptions to the PS layer modify spore surface hydrophobicity and that there are multiple saccharide synthesis pathways involved in spore surface properties.IMPORTANCE Many bacteria are characterized by their ability to form highly resistant spores. The dormant spore state allows these species to survive even the harshest treatments with antimicrobial agents. Spore surface properties are particularly relevant because they influence spore dispersal in various habitats from natural to human-made environments. The spore surface in Bacillus subtilis (crust) is composed of a combination of proteins and polysaccharides. By inactivating the enzymes responsible for the synthesis of spore polysaccharides, we can assess how spore surface properties such as hydrophobicity are modulated by the addition of specific carbohydrates. Our findings indicate that several sporulation gene clusters are responsible for the assembly and allocation of surface polysaccharides. Similar mechanisms could be modulating the dispersal of infectious spore-forming bacteria.
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87
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Wang F, Song T, Jiang H, Pei C, Huang Q, Xi H. Bacillus subtilis Spore Surface Display of Haloalkane Dehalogenase DhaA. Curr Microbiol 2019; 76:1161-1167. [PMID: 31278426 DOI: 10.1007/s00284-019-01723-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Accepted: 06/19/2019] [Indexed: 12/18/2022]
Abstract
The haloalkane dehalogenase DhaA can degrade sulfur mustard (2,2'-dichlorethyl sulfide; also known by its military designation HD) in a rapid and environmentally safe manner. However, DhaA is sensitive to temperature and pH, which limits its applications in natural or harsh environments. Spore surface display technology using resistant spores as a carrier to ensure enzymatic activity can reduce production costs and extend the range of applications of DhaA. To this end, we cloned recombinant Bacillus subtilis spores pHY300PLK-cotg-dhaa-6his/DB104(FH01) for the delivery of DhaA from Rhodococcus rhodochrous NCIMB 13064. A dot blotting showed that the fusion protein CotG-linker-DhaA accounted for 0.41% ± 0.03% (P < 0.01) of total spore coat proteins. Immunofluorescence analyses confirmed that DhaA was displayed on the spore surface. The hydrolyzing activity of DhaA displayed on spores towards the HD analog 2-chloroethyl ethylsulfide was 1.74 ± 0.06 U/mL (P < 0.01), with a specific activity was 0.34 ± 0.04 U/mg (P < 0.01). This is the first demonstration that DhaA displayed on the surface of B. subtilis spores retains enzymatic activity, which suggests that it can be used effectively in real-world applications including bioremediation of contaminated environments.
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Affiliation(s)
- Fuli Wang
- Research Institute of Chemical Defense, Academy of Military Sciences, Beijing, 102205, People's Republic of China.,State Key Laboratory of NBC Protection for Civilian, Academy of Military Sciences, Beijing, 102205, People's Republic of China
| | - Tianyu Song
- Research Institute of Chemical Defense, Academy of Military Sciences, Beijing, 102205, People's Republic of China.,State Key Laboratory of NBC Protection for Civilian, Academy of Military Sciences, Beijing, 102205, People's Republic of China
| | - Hui Jiang
- Research Institute of Chemical Defense, Academy of Military Sciences, Beijing, 102205, People's Republic of China.,State Key Laboratory of NBC Protection for Civilian, Academy of Military Sciences, Beijing, 102205, People's Republic of China
| | - Chengxin Pei
- Research Institute of Chemical Defense, Academy of Military Sciences, Beijing, 102205, People's Republic of China.,State Key Laboratory of NBC Protection for Civilian, Academy of Military Sciences, Beijing, 102205, People's Republic of China
| | - Qibin Huang
- Research Institute of Chemical Defense, Academy of Military Sciences, Beijing, 102205, People's Republic of China.,State Key Laboratory of NBC Protection for Civilian, Academy of Military Sciences, Beijing, 102205, People's Republic of China
| | - Hailing Xi
- Research Institute of Chemical Defense, Academy of Military Sciences, Beijing, 102205, People's Republic of China. .,State Key Laboratory of NBC Protection for Civilian, Academy of Military Sciences, Beijing, 102205, People's Republic of China.
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88
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Awasti N, Anand S, Djira G. Sporulating behavior of Bacillus licheniformis strains influences their population dynamics during raw milk holding. J Dairy Sci 2019; 102:6001-6012. [DOI: 10.3168/jds.2018-15613] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Accepted: 03/23/2019] [Indexed: 01/09/2023]
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89
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Abstract
Bacterial spores can remain dormant for years but possess the remarkable ability to germinate, within minutes, once nutrients become available. However, it still remains elusive how such instant awakening of cellular machineries is achieved. Utilizing Bacillus subtilis as a model, we show that YwlE arginine (Arg) phosphatase is crucial for spore germination. Accordingly, the absence of the Arg kinase McsB accelerated the process. Arg phosphoproteome of dormant spores uncovered a unique set of Arg-phosphorylated proteins involved in key biological functions, including translation and transcription. Consequently, we demonstrate that during germination, YwlE dephosphorylates an Arg site on the ribosome-associated chaperone Tig, enabling its association with the ribosome to reestablish translation. Moreover, we show that Arg dephosphorylation of the housekeeping σ factor A (SigA), mediated by YwlE, facilitates germination by activating the transcriptional machinery. Subsequently, we reveal that transcription is reinitiated at the onset of germination and its recommencement precedes that of translation. Thus, Arg dephosphorylation elicits the most critical stages of spore molecular resumption, placing this unusual post-translational modification as a major regulator of a developmental process in bacteria.
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90
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Touchette MH, Benito de la Puebla H, Ravichandran P, Shen A. SpoIVA-SipL Complex Formation Is Essential for Clostridioides difficile Spore Assembly. J Bacteriol 2019; 201:e00042-19. [PMID: 30692174 PMCID: PMC6436350 DOI: 10.1128/jb.00042-19] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 01/23/2019] [Indexed: 01/05/2023] Open
Abstract
Spores are the major infectious particle of the Gram-positive nosocomial pathogen Clostridioides difficile (formerly Clostridium difficile), but the molecular details of how this organism forms these metabolically dormant cells remain poorly characterized. The composition of the spore coat in C. difficile differs markedly from that defined in the well-studied organism Bacillus subtilis, with only 25% of the ∼70 spore coat proteins being conserved between the two organisms and with only 2 of 9 coat assembly (morphogenetic) proteins defined in B. subtilis having homologs in C. difficile We previously identified SipL as a clostridium-specific coat protein essential for functional spore formation. Heterologous expression analyses in Escherichia coli revealed that SipL directly interacts with C. difficile SpoIVA, a coat-morphogenetic protein conserved in all spore-forming organisms, through SipL's C-terminal LysM domain. In this study, we show that SpoIVA-SipL binding is essential for C. difficile spore formation and identify specific residues within the LysM domain that stabilize this interaction. Fluorescence microscopy analyses indicate that binding of SipL's LysM domain to SpoIVA is required for SipL to localize to the forespore while SpoIVA requires SipL to promote encasement of SpoIVA around the forespore. Since we also show that clostridial LysM domains are functionally interchangeable at least in C. difficile, the basic mechanism for SipL-dependent assembly of clostridial spore coats may be conserved.IMPORTANCE The metabolically dormant spore form of the major nosocomial pathogen Clostridioides difficile is its major infectious particle. However, the mechanisms controlling the formation of this resistant cell type are not well understood, particularly with respect to its outermost layer, the spore coat. We previously identified two spore-morphogenetic proteins in C. difficile: SpoIVA, which is conserved in all spore-forming organisms, and SipL, which is conserved only in the clostridia. Both SpoIVA and SipL are essential for heat-resistant spore formation and directly interact through SipL's C-terminal LysM domain. In this study, we demonstrate that the LysM domain is critical for SipL and SpoIVA function, likely by helping recruit SipL to the forespore during spore morphogenesis. We further identified residues within the LysM domain that are important for binding SpoIVA and, thus, functional spore formation. These findings provide important insight into the molecular mechanisms controlling the assembly of infectious C. difficile spores.
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Affiliation(s)
- Megan H Touchette
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, USA
| | - Hector Benito de la Puebla
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, USA
| | - Priyanka Ravichandran
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, Vermont, USA
| | - Aimee Shen
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, USA
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, Vermont, USA
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91
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Temporal and spatial regulation of protein cross-linking by the pre-assembled substrates of a Bacillus subtilis spore coat transglutaminase. PLoS Genet 2019; 15:e1007912. [PMID: 30958830 PMCID: PMC6490927 DOI: 10.1371/journal.pgen.1007912] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 04/30/2019] [Accepted: 12/21/2018] [Indexed: 11/19/2022] Open
Abstract
In many cases protein assemblies are stabilized by covalent bonds, one example of which is the formation of intra- or intermolecular ε-(γ-glutamyl)lysil cross-links catalyzed by transglutaminases (TGases). Because of the potential for unwanted cross-linking reactions, the activities of many TGases have been shown to be tightly controlled. Bacterial endospores are highly resilient cells in part because they are surrounded by a complex protein coat. Proteins in the coat that surrounds Bacillus subtilis endospores are crosslinked by a TGase (Tgl). Unlike other TGases, however, Tgl is produced in an active form, and efficiently catalyzes amine incorporation and protein cross-linking in vitro with no known additional requirements. The absence of regulatory factors raises questions as to how the activity of Tgl is controlled during spore coat assembly. Here, we show that substrates assembled onto the spore coat prior to Tgl production govern the localization of Tgl to the surface of the developing spore. We also show that Tgl residues important for substrate recognition are crucial for its localization. We identified the glutamyl (Q) and lysil (K) substrate docking sites and we show that residues on the Q side of Tgl are more important for the assembly of Tgl than those on the K side. Thus, the first step in the reaction cycle, the interaction with Q-substrates and formation of an acyl-enzyme intermediate, is also the determinant step in the localization of Tgl. Consistent with the idea that Tg exerts a “spotwelding” activity, cross-linking pre-formed assemblies, we show that C30 is an oblong hexamer in solution that is cross-linked in vitro into high molecular weight forms. Moreover, during the reaction, Tgl becomes part of the cross-linked products. We suggest that the dependency of Tgl on its substrates is used to accurately control the time, location and extent of the enzyme´s activity, directed at the covalent fortification of pre-assembled complexes at the surface of the developing spore. The orderly recruitment of proteins during the assembly of complex macromolecular structures poses challenges throughout cell biology. During endospore development in the bacterium Bacillus subtilis at least 80 proteins synthesized in the mother cell are assembled around the developing spore to form a protective coat. Regulation of coat gene expression has been described in detail but it is unknown how the information encoded by the structures of the proteins guide their assembly. We have examined the assembly of a transglutaminase, Tgl, which introduces ε-(γ-glutamyl)lysil cross-links in coat protein substrates. We describe with molecular detail a substrate-driven assembly model that directs the enzyme to the locations of its substrates where, as we suggest, it exerts a “spotwelding” activity to fortify pre-assembled complexes. The catalytic cysteine, located in a tunnel that spans the Tgl structure, first forms an acyl enzyme intermediate with a glutamine (Q) donor substrate. Then, it engages a lysine (K) donor substrate to form the cross-linked product. We have identified the Q and K acceptor ends of the Tgl tunnel, and we show that substitutions in substrate recognition residues at the Q side impair assembly more strongly than at the K side. Thus, assembly of Tgl parallels its catalytic cycle, directing the enzyme to the pre-formed complexes that are to be cross-linked.
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92
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López M, Calvo T, Prieto M, Múgica-Vidal R, Muro-Fraguas I, Alba-Elías F, Alvarez-Ordóñez A. A Review on Non-thermal Atmospheric Plasma for Food Preservation: Mode of Action, Determinants of Effectiveness, and Applications. Front Microbiol 2019; 10:622. [PMID: 31001215 PMCID: PMC6454144 DOI: 10.3389/fmicb.2019.00622] [Citation(s) in RCA: 97] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Accepted: 03/12/2019] [Indexed: 11/13/2022] Open
Abstract
Non-thermal Atmospheric Plasma (NTAP) is a cutting-edge technology which has gained much attention during the last decade in the food-processing sector as a promising technology for food preservation and maintenance of food safety, with minimal impact on the quality attributes of foods, thanks to its effectiveness in microbial inactivation, including of pathogens, spoilage fungi and bacterial spores, simple design, ease of use, cost-effective operation, short treatment times, lack of toxic effects, and significant reduction of water consumption. This review article provides a general overview of the principles of operation and applications of NTAP in the agri-food sector. In particular, the numerous studies carried out in the last decade aimed at deciphering the influence of different environmental factors and processing parameters on the microbial inactivation attained are discussed. In addition, this review also considers some important studies aimed at elucidating the complex mechanism of microbial inactivation by NTAP. Finally, other potential applications of NTAP in the agri-food sector, apart from food decontamination, are briefly described, and some limitations for the immediate industrial implementation of NTAP are discussed (e.g., impact on the nutritional and sensory quality of treated foods; knowledge on the plasma components and reactive species responsible for the antimicrobial activity; possible toxicity of some of the chemical species generated; scale-up by designing fit-for-purpose equipment).
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Affiliation(s)
- Mercedes López
- Department of Food Hygiene and Technology, Universidad de León, León, Spain
- Institute of Food Science and Technology, Universidad de León, León, Spain
| | - Tamara Calvo
- Department of Food Hygiene and Technology, Universidad de León, León, Spain
| | - Miguel Prieto
- Department of Food Hygiene and Technology, Universidad de León, León, Spain
- Institute of Food Science and Technology, Universidad de León, León, Spain
| | | | | | - Fernando Alba-Elías
- Department of Mechanical Engineering, Universidad de La Rioja, Logroño, Spain
| | - Avelino Alvarez-Ordóñez
- Department of Food Hygiene and Technology, Universidad de León, León, Spain
- Institute of Food Science and Technology, Universidad de León, León, Spain
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93
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de Andrade Cavalcante D, De-Souza MT, de Orem JC, de Magalhães MIA, Martins PH, Boone TJ, Castillo JA, Driks A. Ultrastructural analysis of spores from diverse Bacillales species isolated from Brazilian soil. ENVIRONMENTAL MICROBIOLOGY REPORTS 2019; 11:155-164. [PMID: 30421850 DOI: 10.1111/1758-2229.12713] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Accepted: 11/06/2018] [Indexed: 06/09/2023]
Abstract
Many species in the order Bacillales form a specialized cell type called a spore that is resistant to a range of environmental stresses. Transmission electron microscopy (TEM) reveals that the spore is comprised of a series of concentric shells, surrounding an interior compartment harbouring the spore DNA. The outermost of these shells varies considerably in morphology among species, likely reflecting adaptations to the highly diverse niches in which spores are found. To better characterize the variation in spore ultrastructure among diverse species, we used TEM to analyse spores from a collection of 23 aerobic spore-forming bacteria from the Solo do Distrito Federal (SDF strains), spanning the genera Bacillus, Lysinibacillus, Paenibacillus and Brevibacillus, isolated from soil from central Brazil. We found that the structures of these spores varied widely, as expected. Interestingly, even though these isolates are novel strains of each species, they were structurally very similar to the known examples of each species in the literature. Because in most cases, the species we analysed are poorly characterized, our data provide important evidence regarding which structural features are likely to be constant within a taxon and which are likely to vary.
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Affiliation(s)
| | | | | | | | | | - Tyler J Boone
- Stritch School of Medicine, Department of Microbiology and Immunology, Loyola University Chicago, IL, USA
| | - José A Castillo
- School of Biological Sciences and Engineering, Yachay Tech University, Urcuquí, Ecuador
| | - Adam Driks
- Stritch School of Medicine, Department of Microbiology and Immunology, Loyola University Chicago, IL, USA
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94
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Shrestha R, Sorg JA. Terbium chloride influences Clostridium difficile spore germination. Anaerobe 2019; 58:80-88. [PMID: 30926439 DOI: 10.1016/j.anaerobe.2019.03.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 03/06/2019] [Accepted: 03/25/2019] [Indexed: 02/06/2023]
Abstract
The germination of Clostridium difficile spores is an important stage of the C. difficile life cycle. In other endospore-forming bacteria, the composition of the medium in which the spores are generated influences the abundance of germination-specific proteins, thereby influencing the sensitivity of the spores towards germinants. In C. difficile media composition on the spores has only been reported to influence the number of spores produced. One of the measures of spore germination is the analysis of the release of DPA from the spore core. To detect DPA release in real time, terbium chloride is often added to the germination conditions because Tb3+ complexes with the released DPA and this can be detected using fluorescence measurements. Although C. difficile spores germinate in response to TA and glycine, recently calcium was identified as an enhancer for spore germination. Here, we find that germination by spores prepared in peptone rich media, such as 70:30, is positively influenced by terbium. We hypothesize that, in these assays, Tb3+ functions similarly to calcium. Although the mechanism(s) causing increased sensitivity of the C. difficile spores that are prepared in peptone rich media to terbium is still unknown, we suggest that the TbCl3 concentration used in the analysis of C. difficile DPA release be carefully titrated so as not to misinterpret future findings.
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Affiliation(s)
- Ritu Shrestha
- Department of Biology, Texas A&M University, College Station, TX, 77843, USA
| | - Joseph A Sorg
- Department of Biology, Texas A&M University, College Station, TX, 77843, USA.
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95
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Lim SY, Benner LC, Clark S. Neither thermosonication nor cold sonication is better than pasteurization for milk shelf life. J Dairy Sci 2019; 102:3965-3977. [PMID: 30827557 DOI: 10.3168/jds.2018-15347] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 01/19/2019] [Indexed: 11/19/2022]
Abstract
High-power, low-frequency ultrasound has been suggested as a novel processing technique with the potential to extend milk shelf life via inactivation of bacteria and spores that survive standard pasteurization. The primary objective of this research was to determine whether short-duration (≤60 s) sonication treatment, in conjunction with pasteurization, can increase shelf life while producing no adverse aroma effect. Skim milk was inoculated with Paenibacillus amylolyticus, a spore-forming, thermotolerant and psychrophilic milk contamination bacterium. Milk was sonicated under 6 selected amplitude and time conditions, except for control. Both cold sonicated (C-S) and thermosonicated (T-S) milk and milk treatments were pasteurized; however, T-S milk was sonicated after pasteurization (72.5 ± 0.3°C; mean ± SD), whereas C-S milk was sonicated at 12.5 ± 5°C (mean ± SD) before pasteurization. Milk was refrigerated up to 50 d and total aerobic counts were enumerated on pasteurized control, C-S, and T-S milk weekly. Neither C-S nor T-S treatments reduced total aerobic counts to an equivalent level as pasteurization alone. Counts in pasteurized controls and C-S milk did not exceed 3.00 log cfu/mL for up to 50 d; counts in T-S milk exceeded 5.00 cfu/mL by d 36. Aroma qualities (cooked, lacks freshness, and rubbery) of 2 T-S treatment intensities [170 µm peak-to-peak (p-p) for 60s and 200 µmp-p for 10 s] and pasteurized controls were evaluated by a trained descriptive sensory panel. No significant differences were observed in cooked or lacks freshness aromas among samples. Only the milk treated with 170 µmp-p for 60 s had significantly higher rubbery aroma on d 1 compared with milk treated with 200 µmp-p for 10 s. Although the sensory effects of T-S on milk may not limit the commercial feasibility of cold sonication or thermosonication, conditions that differ from those used in the present study should be considered in the future. Neither C-S nor T-S were appropriate techniques for reducing bacterial count in fluid milk beyond standard pasteurization and, in fact, increased counts of spore-forming spoilage bacteria.
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Affiliation(s)
- Seung-Yong Lim
- Department of Food Science and Biotechnology, Kunsan National University, Gunsan 54150, Republic of Korea
| | - Lily Claire Benner
- Department of Food Science and Human Nutrition, Iowa State University, Ames 55011-1052
| | - Stephanie Clark
- Department of Food Science and Human Nutrition, Iowa State University, Ames 55011-1052.
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96
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Alves Feliciano C, Douché T, Giai Gianetto Q, Matondo M, Martin-Verstraete I, Dupuy B. CotL, a new morphogenetic spore coat protein of Clostridium difficile. Environ Microbiol 2019; 21:984-1003. [PMID: 30556639 DOI: 10.1111/1462-2920.14505] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 11/07/2018] [Accepted: 12/13/2018] [Indexed: 01/01/2023]
Abstract
The strict anaerobe Clostridium difficile is the most common cause of antibiotic-associated diarrhoea. The oxygen-resistant C. difficile spores play a central role in the infectious cycle, contributing to transmission, infection and recurrence. The spore surface layers, the coat and exosporium, enable the spores to resist physical and chemical stress. However, little is known about the mechanisms of their assembly. In this study, we characterized a new spore protein, CotL, which is required for the assembly of the spore coat. The cotL gene was expressed in the mother cell compartment under the dual control of the RNA polymerase sigma factors, σE and σK . CotL was localized in the spore coat, and the spores of the cotL mutant had a major morphologic defect at the level of the coat/exosporium layers. Therefore, the mutant spores contained a reduced amount of several coat/exosporium proteins and a defect in their localization in sporulating cells. Finally, cotL mutant spores were more sensitive to lysozyme and were impaired in germination, a phenotype likely to be associated with the structurally altered coat. Collectively, these results strongly suggest that CotL is a morphogenetic protein essential for the assembly of the spore coat in C. difficile.
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Affiliation(s)
- Carolina Alves Feliciano
- Laboratoire Pathogenèse des Bactéries Anaérobies, Institut Pasteur, Paris, France.,University Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Thibaut Douché
- Plateforme Protéomique, Unité de Spectrométrie de Masse pour La Biologie, CNRS USR 2000, Institut Pasteur, Paris, France
| | - Quentin Giai Gianetto
- Plateforme Protéomique, Unité de Spectrométrie de Masse pour La Biologie, CNRS USR 2000, Institut Pasteur, Paris, France.,Bioinformatics and Biostatistics HUB, C3BI, CNRS USR 3756, Institut Pasteur, Paris, France
| | - Mariette Matondo
- Plateforme Protéomique, Unité de Spectrométrie de Masse pour La Biologie, CNRS USR 2000, Institut Pasteur, Paris, France
| | - Isabelle Martin-Verstraete
- Laboratoire Pathogenèse des Bactéries Anaérobies, Institut Pasteur, Paris, France.,University Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Bruno Dupuy
- Laboratoire Pathogenèse des Bactéries Anaérobies, Institut Pasteur, Paris, France.,University Paris Diderot, Sorbonne Paris Cité, Paris, France
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97
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Shuster B, Khemmani M, Abe K, Huang X, Nakaya Y, Maryn N, Buttar S, Gonzalez AN, Driks A, Sato T, Eichenberger P. Contributions of crust proteins to spore surface properties in Bacillus subtilis. Mol Microbiol 2019; 111:825-843. [PMID: 30582883 DOI: 10.1111/mmi.14194] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/19/2018] [Indexed: 12/27/2022]
Abstract
Surface properties, such as adhesion and hydrophobicity, constrain dispersal of bacterial spores in the environment. In Bacillus subtilis, these properties are influenced by the outermost layer of the spore, the crust. Previous work has shown that two clusters, cotVWXYZ and cgeAB, encode the protein components of the crust. Here, we characterize the respective roles of these genes in surface properties using Bacterial Adherence to Hydrocarbons assays, negative staining of polysaccharides by India ink and Transmission Electron Microscopy. We showed that inactivation of crust genes caused increases in spore relative hydrophobicity, disrupted the spore polysaccharide layer, and impaired crust structure and attachment to the rest of the coat. We also found that cotO, previously identified for its role in outer coat formation, is necessary for proper encasement of the spore by the crust. In parallel, we conducted fluorescence microscopy experiments to determine the full network of genetic dependencies for subcellular localization of crust proteins. We determined that CotZ is required for the localization of most crust proteins, while CgeA is at the bottom of the genetic interaction hierarchy.
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Affiliation(s)
- Bentley Shuster
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, NY, 10003, USA
| | - Mark Khemmani
- Department of Microbiology and Immunology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL, 60153, USA
| | - Kimihiro Abe
- Research Center for Micro-Nano Technology, Hosei University, Koganei, Tokyo, Japan
| | - Xiaoyu Huang
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, NY, 10003, USA
| | - Yusei Nakaya
- Department of Frontier Bioscience, Hosei University, Koganei, Tokyo, Japan
| | - Nina Maryn
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, NY, 10003, USA
| | - Sally Buttar
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, NY, 10003, USA
| | - Adriana N Gonzalez
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, NY, 10003, USA
| | - Adam Driks
- Department of Microbiology and Immunology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL, 60153, USA
| | - Tsutomu Sato
- Research Center for Micro-Nano Technology, Hosei University, Koganei, Tokyo, Japan.,Department of Frontier Bioscience, Hosei University, Koganei, Tokyo, Japan
| | - Patrick Eichenberger
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, NY, 10003, USA
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98
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A LysM Domain Intervenes in Sequential Protein-Protein and Protein-Peptidoglycan Interactions Important for Spore Coat Assembly in Bacillus subtilis. J Bacteriol 2019; 201:JB.00642-18. [PMID: 30455281 DOI: 10.1128/jb.00642-18] [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: 10/19/2018] [Accepted: 11/15/2018] [Indexed: 11/20/2022] Open
Abstract
At a late stage in spore development in Bacillus subtilis, the mother cell directs synthesis of a layer of peptidoglycan known as the cortex between the two forespore membranes, as well as the assembly of a protective protein coat at the surface of the forespore outer membrane. SafA, the key determinant of inner coat assembly, is first recruited to the surface of the developing spore and then encases the spore under the control of the morphogenetic protein SpoVID. SafA has a LysM peptidoglycan-binding domain, SafALysM, and localizes to the cortex-coat interface in mature spores. SafALysM is followed by a region, A, required for an interaction with SpoVID and encasement. We now show that residues D10 and N30 in SafALysM, while involved in the interaction with peptidoglycan, are also required for the interaction with SpoVID and encasement. We further show that single alanine substitutions on residues S11, L12, and I39 of SafALysM that strongly impair binding to purified cortex peptidoglycan affect a later stage in the localization of SafA that is also dependent on the activity of SpoVE, a transglycosylase required for cortex formation. The assembly of SafA thus involves sequential protein-protein and protein-peptidoglycan interactions, mediated by the LysM domain, which are required first for encasement then for the final localization of the protein in mature spores.IMPORTANCE Bacillus subtilis spores are encased in a multiprotein coat that surrounds an underlying peptidoglycan layer, the cortex. How the connection between the two layers is enforced is not well established. Here, we elucidate the role of the peptidoglycan-binding LysM domain, present in two proteins, SafA and SpoVID, that govern the localization of additional proteins to the coat. We found that SafALysM is a protein-protein interaction module during the early stages of coat assembly and a cortex-binding module at late stages in morphogenesis, with the cortex-binding function promoting a tight connection between the cortex and the coat. In contrast, SpoVIDLysM functions only as a protein-protein interaction domain that targets SpoVID to the spore surface at the onset of coat assembly.
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99
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Song T, Wang F, Xiong S, Jiang H. Surface display of organophosphorus-degrading enzymes on the recombinant spore of Bacillus subtilis. Biochem Biophys Res Commun 2019; 510:13-19. [PMID: 30660365 DOI: 10.1016/j.bbrc.2018.12.077] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Accepted: 12/11/2018] [Indexed: 12/17/2022]
Abstract
Organophosphorus-degrading enzymes show high hydrolysis efficiency and provide an environmentally friendly solution to the pollution of organophosphorus compound. However, poor enzyme stability and tedious purification process have limited practical applications. Spore-based display system can provide many advantages, such as safety, low cost, easy preparation and high resistance to harsh conditions. Recently, we have constituted the recombinant spore displaying organophosphorus hydrolase and organophosphorus acid anhydrolase. In the spore display systems, recombinant spores could be reliably produced and normal sporulation was not affected; the activities of recombinant spores were 15.81 and 10.67 U/mg spores (dry weight) respectively; furthermore, the recombinant spores exhibited significantly enhanced resistance to various harsh conditions compared to free-form enzymes. These results indicated that the spore display could contribute to the practical application of organophosphorus-degrading enzymes and provide a promising solution to bioremediation of organophosphorus compounds.
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Affiliation(s)
- Tianyu Song
- Research Institute of Chemical Defense, Academy of Military Sciences, Beijing, 102205, PR China; State Key Laboratory of NBC Protection for Civilian, Academy of Military Sciences, Beijing, 102205, PR China
| | - Fuli Wang
- State Key Laboratory of NBC Protection for Civilian, Academy of Military Sciences, Beijing, 102205, PR China
| | - Shanshan Xiong
- Research Institute of Chemical Defense, Academy of Military Sciences, Beijing, 102205, PR China; State Key Laboratory of NBC Protection for Civilian, Academy of Military Sciences, Beijing, 102205, PR China
| | - Hui Jiang
- Research Institute of Chemical Defense, Academy of Military Sciences, Beijing, 102205, PR China; State Key Laboratory of NBC Protection for Civilian, Academy of Military Sciences, Beijing, 102205, PR China.
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Lv R, Zou M, Chantapakul T, Chen W, Muhammad AI, Zhou J, Ding T, Ye X, Liu D. Effect of ultrasonication and thermal and pressure treatments, individually and combined, on inactivation of Bacillus cereus spores. Appl Microbiol Biotechnol 2019; 103:2329-2338. [PMID: 30627794 DOI: 10.1007/s00253-018-9559-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 11/30/2018] [Accepted: 12/05/2018] [Indexed: 01/03/2023]
Abstract
Bacillus cereus spores are a concern to the food industry due to their high resistance to processing and their ability to germinate to vegetative cells under suitable conditions. This research aimed to elucidate the mechanisms of Bacillus cereus spore inactivation under ultrasonication (US) combined with thermal (thermosonication, TS) treatments, with pressure (manosonication, MS) treatments, and with thermal and pressure (manothermosonication, MTS) treatments. Electronic microscopy, dipicolinic acid (DPA) release, and flow cytometric assessments were used to investigate the inactivation effect and understand the inactivation mechanisms. The sporicidal effects of the US and thermal treatment were slight, and the MS and TS also showed little inactivation effect. However, ultrasonication promoted the detachment of the exosporium, thereby reducing the spore's ability to adhere to a surface, while the thermal treatment induced a decrease in the electron density in the nucleoid of bacterium, which retained a relatively intact exosporium and coat. MS caused 92.54% DPA release, which might be due to triggering of the germinant receptors or releasing of ions and Ca2+-DPA. In addition, the morphological changes such as core hydration and cortex degradation were significant after treatment with MS. The release of DPA and the morphological changes were responsible for the reduction in thermal resistance. The MTS showed a remarkable inactivation effect of 3.12 log CFU/mL reductions after 30 min of treatment. It was the most effective treatment and exhibited a large fraction of damage. In addition, the MTS had a significant impact on the intracellular structure of the spores, with the coat destroyed and the cortex damaged. These results indicated that ultrasonication combined with thermal and pressure treatments had a significant sporicidal effect on Bacillus cereus spores and could be a promising green sterilization technology.
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Affiliation(s)
- Ruiling Lv
- College of Biosystems Engineering and Food Science, National-Local Joint Engineering Laboratory of Intelligent Food Technology and Equipment, Zhejiang Key Laboratory for Agro-Food Processing, Zhejiang R and D Center for Food Technology and Equipment, Zhejiang University, 866 Yuhangtang Rd., Hangzhou, 310058, China
| | - Mingming Zou
- College of Biosystems Engineering and Food Science, National-Local Joint Engineering Laboratory of Intelligent Food Technology and Equipment, Zhejiang Key Laboratory for Agro-Food Processing, Zhejiang R and D Center for Food Technology and Equipment, Zhejiang University, 866 Yuhangtang Rd., Hangzhou, 310058, China
| | - Thunthacha Chantapakul
- College of Biosystems Engineering and Food Science, National-Local Joint Engineering Laboratory of Intelligent Food Technology and Equipment, Zhejiang Key Laboratory for Agro-Food Processing, Zhejiang R and D Center for Food Technology and Equipment, Zhejiang University, 866 Yuhangtang Rd., Hangzhou, 310058, China
| | - Weijun Chen
- College of Biosystems Engineering and Food Science, National-Local Joint Engineering Laboratory of Intelligent Food Technology and Equipment, Zhejiang Key Laboratory for Agro-Food Processing, Zhejiang R and D Center for Food Technology and Equipment, Zhejiang University, 866 Yuhangtang Rd., Hangzhou, 310058, China
| | - Aliyu Idris Muhammad
- College of Biosystems Engineering and Food Science, National-Local Joint Engineering Laboratory of Intelligent Food Technology and Equipment, Zhejiang Key Laboratory for Agro-Food Processing, Zhejiang R and D Center for Food Technology and Equipment, Zhejiang University, 866 Yuhangtang Rd., Hangzhou, 310058, China
| | - Jianwei Zhou
- College of Biosystems Engineering and Food Science, National-Local Joint Engineering Laboratory of Intelligent Food Technology and Equipment, Zhejiang Key Laboratory for Agro-Food Processing, Zhejiang R and D Center for Food Technology and Equipment, Zhejiang University, 866 Yuhangtang Rd., Hangzhou, 310058, China.,Ningbo Institute of Technology, Zhejiang University, Ningbo, 315100, China
| | - Tian Ding
- College of Biosystems Engineering and Food Science, National-Local Joint Engineering Laboratory of Intelligent Food Technology and Equipment, Zhejiang Key Laboratory for Agro-Food Processing, Zhejiang R and D Center for Food Technology and Equipment, Zhejiang University, 866 Yuhangtang Rd., Hangzhou, 310058, China
| | - Xingqian Ye
- College of Biosystems Engineering and Food Science, National-Local Joint Engineering Laboratory of Intelligent Food Technology and Equipment, Zhejiang Key Laboratory for Agro-Food Processing, Zhejiang R and D Center for Food Technology and Equipment, Zhejiang University, 866 Yuhangtang Rd., Hangzhou, 310058, China
| | - Donghong Liu
- College of Biosystems Engineering and Food Science, National-Local Joint Engineering Laboratory of Intelligent Food Technology and Equipment, Zhejiang Key Laboratory for Agro-Food Processing, Zhejiang R and D Center for Food Technology and Equipment, Zhejiang University, 866 Yuhangtang Rd., Hangzhou, 310058, China. .,Fuli Institute of Food Science, Zhejiang University, Hangzhou, 310058, China.
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