Bacillus cereus growth and biofilm formation: the impact of substratum, iron sources, and transcriptional regulator Sigma 54

Research output: Thesisinternal PhD, WU

Abstract

Biofilms are surface-associated communities of microbial cells embedded in a matrix of extracellular polymers. It is generally accepted that the biofilm growth mode represents the most common lifestyle of microorganisms. Next to beneficial biofilms used in biotechnology applications, undesired biofilms can be formed by spoilage and pathogenic microorganisms in food production environments. Bacillus cereus is a foodborne human pathogen able to cause two types of food poisoning, emetic and diarrheal. B. cereus can persist in factory environments in the form of biofilms, which can become a source of food contamination. This thesis adds to the knowledge about (a)biotic factors and conditions that affect B. cereus biofilm formation, including the effect of type of substratum such as polystyrene and stainless steel, with the latter supporting the highest biofilm formation for all tested strains including two reference strains and 20 food isolates. The ability of B. cereus to use a variety of iron sources was subsequently studied in these 22 strains and linked to the genes encoding iron transport systems present in the respective genomes, revealing significant diversity in the capacity to use complex and non-complex iron sources for growth and biofilm formation. For spore forming Bacilli, biofilm formation and sporulation are two intertwined cellular processes and studies in wet and dry (air-exposed) biofilms revealed differences in sporulation rate and efficacy, with biofilm-derived spores showing higher heat resistance than their planktonic counterparts. Additionally, comparative phenotype and transcriptome analysis of B. cereus wild type and a Sigma 54 deletion mutant provided insight into the pleiotropic role of this transcriptional regulator in B. cereus biofilm formation and physiology in general. Taken together, this knowledge improves our understanding of the biofilm lifecycle of this notorious food-borne human pathogen and provides clues which can help to reduce the domestication of this microorganism in production environments.

Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • Wageningen University
Supervisors/Advisors
  • Abee, Tjakko, Promotor
  • Nierop Groot, Masja, Co-promotor
Award date18 Apr 2017
Place of PublicationWageningen
Publisher
Print ISBNs9789463431194
DOIs
Publication statusPublished - 2017

Fingerprint

Bacillus cereus
Biofilms
Iron
Growth
Spores
Food
Food Contamination
Emetics
Aptitude
Foodborne Diseases
Polystyrenes
Stainless Steel
Gene Expression Profiling
Biotechnology
Bacillus
Extracellular Matrix
Life Style
Polymers

Keywords

  • microorganisms
  • bacillus cereus
  • food contamination
  • biofilms
  • foodborne pathogens
  • abiotic conditions
  • sporulation

Cite this

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title = "Bacillus cereus growth and biofilm formation: the impact of substratum, iron sources, and transcriptional regulator Sigma 54",
abstract = "Biofilms are surface-associated communities of microbial cells embedded in a matrix of extracellular polymers. It is generally accepted that the biofilm growth mode represents the most common lifestyle of microorganisms. Next to beneficial biofilms used in biotechnology applications, undesired biofilms can be formed by spoilage and pathogenic microorganisms in food production environments. Bacillus cereus is a foodborne human pathogen able to cause two types of food poisoning, emetic and diarrheal. B. cereus can persist in factory environments in the form of biofilms, which can become a source of food contamination. This thesis adds to the knowledge about (a)biotic factors and conditions that affect B. cereus biofilm formation, including the effect of type of substratum such as polystyrene and stainless steel, with the latter supporting the highest biofilm formation for all tested strains including two reference strains and 20 food isolates. The ability of B. cereus to use a variety of iron sources was subsequently studied in these 22 strains and linked to the genes encoding iron transport systems present in the respective genomes, revealing significant diversity in the capacity to use complex and non-complex iron sources for growth and biofilm formation. For spore forming Bacilli, biofilm formation and sporulation are two intertwined cellular processes and studies in wet and dry (air-exposed) biofilms revealed differences in sporulation rate and efficacy, with biofilm-derived spores showing higher heat resistance than their planktonic counterparts. Additionally, comparative phenotype and transcriptome analysis of B. cereus wild type and a Sigma 54 deletion mutant provided insight into the pleiotropic role of this transcriptional regulator in B. cereus biofilm formation and physiology in general. Taken together, this knowledge improves our understanding of the biofilm lifecycle of this notorious food-borne human pathogen and provides clues which can help to reduce the domestication of this microorganism in production environments.",
keywords = "microorganisms, bacillus cereus, food contamination, biofilms, foodborne pathogens, abiotic conditions, sporulation, micro-organismen, bacillus cereus, voedselbesmetting, biofilms, voedselpathogenen, abiotiek, sporulatie",
author = "Hasmik Hayrapetyan",
note = "WU thesis 6623 Includes bibliographic references. - With summary in English",
year = "2017",
doi = "10.18174/408256",
language = "English",
isbn = "9789463431194",
publisher = "Wageningen University",
school = "Wageningen University",

}

Bacillus cereus growth and biofilm formation: the impact of substratum, iron sources, and transcriptional regulator Sigma 54. / Hayrapetyan, Hasmik.

Wageningen : Wageningen University, 2017. 181 p.

Research output: Thesisinternal PhD, WU

TY - THES

T1 - Bacillus cereus growth and biofilm formation: the impact of substratum, iron sources, and transcriptional regulator Sigma 54

AU - Hayrapetyan, Hasmik

N1 - WU thesis 6623 Includes bibliographic references. - With summary in English

PY - 2017

Y1 - 2017

N2 - Biofilms are surface-associated communities of microbial cells embedded in a matrix of extracellular polymers. It is generally accepted that the biofilm growth mode represents the most common lifestyle of microorganisms. Next to beneficial biofilms used in biotechnology applications, undesired biofilms can be formed by spoilage and pathogenic microorganisms in food production environments. Bacillus cereus is a foodborne human pathogen able to cause two types of food poisoning, emetic and diarrheal. B. cereus can persist in factory environments in the form of biofilms, which can become a source of food contamination. This thesis adds to the knowledge about (a)biotic factors and conditions that affect B. cereus biofilm formation, including the effect of type of substratum such as polystyrene and stainless steel, with the latter supporting the highest biofilm formation for all tested strains including two reference strains and 20 food isolates. The ability of B. cereus to use a variety of iron sources was subsequently studied in these 22 strains and linked to the genes encoding iron transport systems present in the respective genomes, revealing significant diversity in the capacity to use complex and non-complex iron sources for growth and biofilm formation. For spore forming Bacilli, biofilm formation and sporulation are two intertwined cellular processes and studies in wet and dry (air-exposed) biofilms revealed differences in sporulation rate and efficacy, with biofilm-derived spores showing higher heat resistance than their planktonic counterparts. Additionally, comparative phenotype and transcriptome analysis of B. cereus wild type and a Sigma 54 deletion mutant provided insight into the pleiotropic role of this transcriptional regulator in B. cereus biofilm formation and physiology in general. Taken together, this knowledge improves our understanding of the biofilm lifecycle of this notorious food-borne human pathogen and provides clues which can help to reduce the domestication of this microorganism in production environments.

AB - Biofilms are surface-associated communities of microbial cells embedded in a matrix of extracellular polymers. It is generally accepted that the biofilm growth mode represents the most common lifestyle of microorganisms. Next to beneficial biofilms used in biotechnology applications, undesired biofilms can be formed by spoilage and pathogenic microorganisms in food production environments. Bacillus cereus is a foodborne human pathogen able to cause two types of food poisoning, emetic and diarrheal. B. cereus can persist in factory environments in the form of biofilms, which can become a source of food contamination. This thesis adds to the knowledge about (a)biotic factors and conditions that affect B. cereus biofilm formation, including the effect of type of substratum such as polystyrene and stainless steel, with the latter supporting the highest biofilm formation for all tested strains including two reference strains and 20 food isolates. The ability of B. cereus to use a variety of iron sources was subsequently studied in these 22 strains and linked to the genes encoding iron transport systems present in the respective genomes, revealing significant diversity in the capacity to use complex and non-complex iron sources for growth and biofilm formation. For spore forming Bacilli, biofilm formation and sporulation are two intertwined cellular processes and studies in wet and dry (air-exposed) biofilms revealed differences in sporulation rate and efficacy, with biofilm-derived spores showing higher heat resistance than their planktonic counterparts. Additionally, comparative phenotype and transcriptome analysis of B. cereus wild type and a Sigma 54 deletion mutant provided insight into the pleiotropic role of this transcriptional regulator in B. cereus biofilm formation and physiology in general. Taken together, this knowledge improves our understanding of the biofilm lifecycle of this notorious food-borne human pathogen and provides clues which can help to reduce the domestication of this microorganism in production environments.

KW - microorganisms

KW - bacillus cereus

KW - food contamination

KW - biofilms

KW - foodborne pathogens

KW - abiotic conditions

KW - sporulation

KW - micro-organismen

KW - bacillus cereus

KW - voedselbesmetting

KW - biofilms

KW - voedselpathogenen

KW - abiotiek

KW - sporulatie

U2 - 10.18174/408256

DO - 10.18174/408256

M3 - internal PhD, WU

SN - 9789463431194

PB - Wageningen University

CY - Wageningen

ER -