Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Analysis of germination capacity and germinant receptor (sub)clusters of genomesequenced Bacillus cereus environmental isolates and model strains
    Warda, Alicja K. ; Xiao, Yinghua ; Boekhorst, Jos ; Wells-Bennik, Marjon H.J. ; Nierop Groot, Masja N. ; Abee, Tjakko - \ 2017
    Applied and Environmental Microbiology 83 (2017)4. - ISSN 0099-2240
    Bacillus cereus - Germination - Sporeformer - Spores

    Spore germination of 17 Bacillus cereus food isolates and reference strains was evaluated using flow cytometry analysis in combination with fluorescent staining at a single-spore level. This approach allowed for rapid collection of germination data under more than 20 conditions, including heat activation of spores, germination in complex media (brain heart infusion [BHI] and tryptone soy broth [TSB]), and exposure to saturating concentrations of single amino acids and the combination of alanine and inosine. Whole-genome sequence comparison revealed a total of 11 clusters of operons encoding germinant receptors (GRs): GerK, GerI, and GerL were present in all strains, whereas GerR, GerS, GerG, GerQ, GerX, GerF, GerW, and GerZ (sub)clusters showed a more diverse presence/absence in different strains. The spores of tested strains displayed high diversity with regard to their sensitivity and responsiveness to selected germinants and heat activation. The two laboratory strains, B. cereus ATCC 14579 and ATCC 10987, and 11 food isolates showed a good germination response under a range of conditions, whereas four other strains (B. cereus B4085, B4086, B4116, and B4153) belonging to phylogenetic group IIIA showed a very weak germination response even in BHI and TSB media. Germination responses could not be linked to specific (combinations of) GRs, but it was noted that the four group IIIA strains contained pseudogenes or variants of subunit C in their gerL cluster. Additionally, two of those strains (B4086 and B4153) carried pseudogenes in the gerK and gerRI (sub)clusters that possibly affected the functionality of these GRs.

    Comparative genomics of iron-transporting systems in Bacillus cereus strains and impact of iron sources on growth and biofilm formation
    Hayrapetyan, Hasmik ; Siezen, Roland ; Abee, Tjakko ; Nierop Groot, Masja - \ 2016
    Frontiers in Microbiology 7 (2016)JUN. - ISSN 1664-302X
    Bacillus cereus - Biofilm formation - Complex iron sources - Genotypes - Growth - Iron transport

    Iron is an important element for bacterial viability, however it is not readily available in most environments. We studied the ability of 20 undomesticated food isolates of Bacillus cereus and two reference strains for capacity to use different (complex) iron sources for growth and biofilm formation. Studies were performed in media containing the iron scavenger 2,2-Bipyridine. Transcriptome analysis using B. cereus ATCC 10987 indeed showed upregulation of predicted iron transporters in the presence of 2,2-Bipyridine, confirming that iron was depleted upon its addition. Next, the impact of iron sources on growth performance of the 22 strains was assessed and correlations between growth stimulation and presence of putative iron transporter systems in the genome sequences were analyzed. All 22 strains effectively used Fe citrate and FeCl3 for growth, and possessed genes for biosynthesis of the siderophore bacillibactin, whereas seven strains lacked genes for synthesis of petrobactin. Hemoglobin could be used by all strains with the exception of one strain that lacked functional petrobactin and IlsA systems. Hemin could be used by the majority of the tested strains (19 of 22). Notably, transferrin, ferritin, and lactoferrin were not commonly used by B. cereus for growth, as these iron sources could be used by 6, 3, and 2 strains, respectively. Furthermore, biofilm formation was found to be affected by the type of iron source used, including stimulation of biofilms at liquid-air interphase (FeCl3 and Fe citrate) and formation of submerged type biofilms (hemin and lactoferrin). Our results show strain variability in the genome-encoded repertoire of iron-transporting systems and differences in efficacy to use complex iron sources for growth and biofilm formation. These features may affect B. cereus survival and persistence in specific niches.

    Public and private standards for dried culinary herbs and spices—Part II : Production and product standards for ensuring microbiological safety
    Schaarschmidt, Sara ; Spradau, Franziska ; Mank, Helmut ; Banach, Jennifer L. ; Fels, Ine van der; Hiller, Petra ; Appel, Bernd ; Bräunig, Juliane ; Wichmann-Schauer, Heidi ; Mader, Anneluise - \ 2016
    Food Control 70 (2016). - ISSN 0956-7135 - p. 360 - 370.
    Bacillus cereus - Clostridium perfringens - Food safety testing - Good practices - Microbiological criteria - Salmonella spp.

    Dried culinary herbs and spices (DCHS) are minor food components with widespread use. Despite their low water activity, some microorganisms—including pathogenic and toxigenic ones—can survive in DCHS. The addition of microbial contaminated DCHS to ready-to-eat food in combination with improper food storage can pose a serious health risk for the consumer. In the past, several food-borne disease outbreaks were related to microbial contaminated spices. The aim of this study was to provide an overview on (i) spice/herb production standards important for promoting food safety by preventing microbial contaminations, (ii) public and private standards providing microbiological criteria to assess the microbiological safety of DCHS, and (iii) product testing performed by DCHS producing/processing businesses to comply with these standards. For that, a literature search and a survey among herb/spice businesses were conducted. Several good practices and production guidelines specific for the primary production and/or processing of culinary herbs and spices were found. Microbiological criteria specific for DCHS are usually rare, but some national standards (mostly of non-EU member states) as well as recommendations by private bodies could be identified. By EU law, no mandatory microbiological criteria specific for DCHS are laid down. The survey indicated a frequent application of business-to-business agreements. The microbiological quality of DCHS was tested by the survey participants mainly in a routine manner by checking every lot or based on buyer–seller agreements. Risk-based testing was less common, which differed to chemical safety testing. Upon import into the EU, testing appeared to be performed predominantly in a routine manner for the pathogenic bacteria Salmonella spp., sulphite-reducing clostridia (including Clostridium perfringens), Bacillus cereus, and Staphylococcus aureus.

    Sporulation dynamics and spore heat resistance in wet and dry biofilms of Bacillus cereus
    Hayrapetyan, Hasmik ; Abee, Tjakko ; Nierop Groot, Masja - \ 2016
    Food Control 60 (2016). - ISSN 0956-7135 - p. 493 - 499.
    Air-exposure - Bacillus cereus - Biofilm - Drying - Heat resistance - Spores

    Environmental conditions and growth history can affect the sporulation process as well as subsequent properties of formed spores. The sporulation dynamics was studied in wet and air-dried biofilms formed on stainless steel (SS) and polystyrene (PS) for Bacillus cereus ATCC 10987 and the undomesticated food isolate B. cereus NIZO 4080. After harvesting and maturation, the wet heat resistance of spores obtained from these biofilms was tested and compared to planktonic and agar plate-derived spores. Drying/air exposure of the preformed 24 h old biofilms accelerated spore formation for both strains and resulted in higher final spore percentages. Prolonged dry incubation of more than three days triggered germination of spores in the biofilms of ATCC 10987. Spores harvested from wet biofilms on SS displayed the highest heat resistance compared to liquid, agar plate and PS biofilm derived spores. The D95 °C values for these spores were 17 and 22 min for NIZO 4080 and ATCC 10987, respectively, which was 2 and 1.2 fold higher compared to planktonic spores of these strains. Spores obtained from dried biofilms of ATCC 10987 displayed reduced heat resistance compared to wet biofilm spores. The results indicate that environmental conditions encountered by biofilms affect sporulation dynamics and spore heat resistance, thus affecting subsequent quality issues and safety risks related to these biofilms.

    Transcriptional analysis of Bacillus cereus ATCC 14579 and its ccpA deletion strain grown with and without glucose
    Wijman, Janneke ; Abee, Tjakko ; Voort, M. van der - \ 2015
    Wageningen UR
    GSE20057 - Bacillus cereus ATCC 14579 - GSE20057 - Bacillus cereus - PRJNA124327
    The influence of the presence of glucose in the Y1 growth medium of Bacillus cereus strain ATCC 14579 was studied by transcriptional analysis. Furthermore, the role of CcpA in glucose induction or repression of gene expression was assessed by use of a ccpA deletion strain. In total, 300 genes were glucose repressed and 173 genes glucose activated. For 212 genes the glucose repression was clearly CcpA dependent, whereas for 116 genes CcpA dependent glucose induction was observed. Functional analysis of the glucose regulated genes showed these genes mainly to be involve in energy production and conversion and in metabolism. Furthermore, genes that were glucose repressed were shown to be involved in cell motility.
    Comparative transcriptome analysis of biofilm and planktonic cells of Bacillus cereus ATCC 10987
    Wijman, Janneke ; Mols, M. ; Tempelaars, Marcel ; Abee, Tjakko - \ 2015
    Wageningen UR
    GSE24620 - Bacillus cereus - PRJNA133579 - GSE24620 - Bacillus cereus ATCC 10987 - PRJNA133579
    Planktonic and biofilm cells of Bacillus cereus ATCC 14579 and ATCC 10987 were studied using microscopy and transcriptome analysis. By microscopy, clear differences could be observed between biofilm and planktonic cells as well as between the two strains. By using hierarchical clustering of the transcriptome data, little difference was observed between the biofilm cells of B. cereus ATCC 14579 and ATCC 10987. Different responses between biofilm and planktonic cells could be identified using transcriptome analysis. Biofilm formation seemed to cause a shift in metabolism with up- or down-regulation of genes involved in different metabolic pathways. Genes involved in motility were down-regulated. No clear up-regulation related to capsular or extracellular polysaccharides was observed. Sporulation was observed in biofilm cells using microscopy, which was corroborated with up-regulation of genes involved in sporulation in biofilm cells. The results obtained in this study provide insight in general and strain specific behavior of B. cereus cells in multicellular communities.
    Comparative transcriptome analysis of biofilm and planktonic cells of Bacillus cereus ATCC 14579
    Wijman, Janneke ; Mols, M. ; Tempelaars, Marcel ; Abee, Tjakko - \ 2015
    Wageningen UR
    GSE24619 - Bacillus cereus - PRJNA133577 - GSE24619 - Bacillus cereus ATCC 14579 - PRJNA133577
    Planktonic and biofilm cells of Bacillus cereus ATCC 14579 and ATCC 10987 were studied using microscopy and transcriptome analysis. By microscopy, clear differences could be observed between biofilm and planktonic cells as well as between the two strains. By using hierarchical clustering of the transcriptome data, little difference was observed between the biofilm cells of B. cereus ATCC 14579 and ATCC 10987. Different responses between biofilm and planktonic cells could be identified using transcriptome analysis. Biofilm formation seemed to cause a shift in metabolism with up- or down-regulation of genes involved in different metabolic pathways. Genes involved in motility were down-regulated. No clear up-regulation related to capsular or extracellular polysaccharides was observed. Sporulation was observed in biofilm cells using microscopy, which was corroborated with up-regulation of genes involved in sporulation in biofilm cells. The results obtained in this study provide insight in general and strain specific behavior of B. cereus cells in multicellular communities.
    Comparative transcriptome analysis of biofilm and planktonic cells of Bacillus cereus
    Wijman, J.G.E. - \ 2015
    Bacillus cereus - GSE24635 - PRJNA132469
    This SuperSeries is composed of the SubSeries listed below.
    Phylogenetic footprinting and transcriptome profiling reveal new roles for two Bacillus cereus two-component systems
    Been, M. de; Brillard, J. ; Brousolle, V. ; Abee, Tjakko - \ 2014
    Wageningen UR
    GSE18523 - Bacillus cereus - PRJNA120197 - GSE18523 - Bacillus cereus ATCC 14579 - PRJNA120197
    Members of the Bacillus cereus group can adapt to a wide range of environmental challenges. In bacteria, these challenges are often translated into a transcriptional response via the cognate response regulators (RRs) of specialized two-component systems (TCSs). We have previously developed a phylogenetic footprinting approach that was successfully implemented to predict specific binding sites (operators) and target genes for the RRs of B. cereus and related species. In this study, this footprinting approach was integrated with transcriptome analyses of two B. cereus TCS deletion mutants, involving the TCSs YvrHG and YufLM. Comparison of mutant versus wild-type transcriptomes revealed that the respective TCSs were significantly active during the exponential growth phase in rich medium and that the footprinting-based predictions were accurate for the two TCSs. Moreover, the predicted specific operators were used in combination with the transcriptome data to guide the identification of more extended TCS regulons. This revealed new roles for the respective TCSs, including the participation in an intricate transcriptional network involved in antibiotic resistance, including the confirmed resistance to oxolinic acid (YvrHG) and the confirmed uptake and metabolism of fumarate and the repression of fermentative pathways (YufLM).
    Analysis of germination and outgrowth of sorbic acid-stressed Bacillus cereus ATCC 14579 spores.
    Melis, Clint van; Nierop Groot, Masja ; Tempelaars, Marcel ; Moezelaar, Roy ; Abee, Tjakko - \ 2010
    GSE19186 - Bacillus cereus - PRJNA120671 - Bacillus cereus ATCC 14579
    Sorbic acid (SA) is widely used as a preservative, but the effect of SA on spore germination and outgrowth has gained limited attention up to now. Therefore, the effect of sorbic acid on germination of spores of B. cereus strain ATCC 14579 was analyzed both at phenotype and transcriptome level. Spore germination and outgrowth was assessed at pH 5.5 without and with 0.75, 1.5 and 3.0mM (final concentrations) undissociated sorbic acid (HSA). This resulted in distinct HSA concentration-dependent phenotypes, varying from delays in germination and outgrowth to complete blockage of germination at 3.0mM HSA. The phenotypes reflecting different stages in the germination process could be confirmed using flow cytometry and could be recognized at transcriptome level by distinct expression profiles. In the absence and presence of 0.75 and 1.5mM HSA, similar cellular ATP levels were found up to the initial stage of outgrowth, suggesting that HSA-induced inhibition of outgrowth is not caused by depletion of ATP. Transcriptome analysis revealed the presence of a limited number of transcripts in dormant spores, outgrowth related expression, and genes specifically associated with sorbic acid stress, including alterations in cell envelope and multi-drug resistance. The potential role of these HSA-stress associated genes in spore outgrowth is discussed.
    Comparative transcriptome and phenotype analysis of Bacillus cereus in response to disinfectant treatments
    Ceragioli, Mara ; Mols, J.M. ; Moezelaar, Roy ; Ghelardi, Emilia ; Senesi, Sonia ; Abee, Tjakko - \ 2010
    WUR
    GSE18807 - Bacillus cereus - PRJNA121223 - GSE18807 - Bacillus cereus ATCC 14579 - PRJNA121223
    Antimicrobial chemicals are widely applied to clean and disinfect food-contacting surfaces. However, the cellular response of bacteria, such as Bacillus cereus, to various disinfectants is unclear. In this study, the physiological and genome-wide transcriptional responses of B. cereus ATCC 14579 exposed to four different disinfectants (i.e., benzalkonium chloride, sodium hypochlorite, hydrogen peroxide, and peracetic acid) were analyzed. The physiological response of B. cereus to different concentrations of the disinfectants used was investigated. For each disinfectant, concentrations leading to the attenuation of growth, growth arrest, and cell death were studied in more detail. The simultaneous analysis of the transcriptional responses of B. cereus upon exposure to the different concentrations of disinfectants revealed common responses induced by the four disinfectants. Notably, genes involved in the general and oxidative stress responses were commonly up-regulated. Furthermore, the obtained results indicate that all the disinfectants also induce specific responses. Exposure to benzalkonium chloride, a disinfectant known to induce membrane damage, specifically induced genes involved in the fatty acid metabolism. Benzalkonium chloride induced-membrane damage was confirmed by fluorescence microscopy and fatty acid analysis confirmed that fatty acid composition of cell membrane was affected upon exposure to benzalkonium chloride. Sodium hypochlorite induced genes involved in sulfur and sulfur-containing amino acids metabolism, which correlated with the observed sodium hypochlorite-specific induction of oxidation of sulphydryl groups. Hydrogen peroxide and peracetic acid exposures induced genes involved in DNA damage and the SOS response. Notably, hydrogen peroxide and peracetic acid-treated cells exhibited higher mutation rates corroborating with the induced SOS response. Understanding the mechanisms displayed by microorganisms coping with disinfectants-induced stress may allow for design of more efficient sequential and/or disinfectant combination treatments in food processing environments.
    Transcriptomic and physiological responses of Bacillus cereus to organic and inorganic acid down-shocks
    Mols, J.M. ; Kranenburg, Richard van; Tempelaars, Marcel ; Schaik, W. van; Moezelaar, Roy ; Abee, Tjakko - \ 2009
    GSE15140 - Bacillus cereus - PRJNA114901
    Comparative phenotype and transcriptome analyses were performed with Bacillus cereus ATCC 14579 exposed to acid down-shock to pH 5.5 set with different acidulants. When acidified with hydrochloric acid (HCl), growth was diminished, whereas 2 mM undissociated lactic acid (HL) or acetic acid (HAc) stopped growth without inactivation (bacteriostatic condition), and 15 mM undissociated HAc caused growth arrest and, finally, cell death, as reflected by a 3 to 4 log inactivation (bactericidal condition). Within the first 60 min after pH down-shock, the intracellular ATP levels of cultures shocked with HCl were increased. The bacteriostatic pH shocks did not result in increased nor decreased intracellular ATP levels, indicating that the high energy status within the stressed aerobically grown B. cereus cells could be maintained. In contrast, exposure to 15 mM undissociated HAc resulted in significant lower ATP levels, which was in accordance with the observed inactivation. The transcriptomic responses pH down-shocked cultures were studied in the same time frame. The analyses revealed general and specific responses coupled to the different phenotypes and the acidulant used. The general acid stress response, shown in all different pH shocks, involves modulation of pyruvate metabolism and an oxidative stress response. The shifts in pyruvate metabolism include induction dehydrogenases of a butanediol fermentation pathway under non-lethal acid stress conditions and of lactate, formate, and ethanol fermentation pathways under 15 mM HAc stress. Other 15 mM HAc-specific responses were induction of the alternative electron-transport systems, including cydAB, and fatty acid biosynthesis genes. Differences in gene expression for the bacteriostatic organic acid stress conditions compared to the growth-retarded inorganic stress condition indicated a more stringent oxidative stress response, including induction of an additional catalase gene and a gene encoding a Dps-like protein. Moreover, modulations in amino acid and oligopeptide transport were also found for the 2 mM HAc and HL shocks. HL-specific and HAc-specific responses both involve amino acid metabolism. Our study on the genome-wide responses of aerobically grown B. cereus pH 5.5 shocks provides a unique overview of the different responses induced by three acidulants relevant for food preservation.
    Comparative transcriptome and phenotype analysis of acid-stressed Bacillus cereus strain ATCC 10987
    Mols, J.M. ; Kranenburg, Richard van; Melis, Clint van; Moezelaar, Roy ; Abee, Tjakko - \ 2009
    GSE13729 - Bacillus cereus - PRJNA114633
    The food-borne human pathogen Bacillus cereus is found in environments that often have a low pH, such as food and soil. The physiological response upon exposure to several levels of acidity were investigated of B. cereus model strain ATCC 10987, to elucidate the response of B. cereus to acid stress. pH 5.4, pH 5.0, pH 4.8 and pH 4.5 were selected to conduct microarray analyses, based on the differences in physiological response upon exposure to the acid conditions. The transcriptome data revealed response specific profiles. Showing mechanisms induced upon all the different acid down-shocks, such as nitrate reductase and energy production genes, and several genes specifically expressed differentially in mild or lethal levels of acidity, such as F1F0-ATPase and cydAB. Furthermore, mechanisms involved in oxidative stress response were found highly up-regulated in response to both mild and lethal acid stress. The induction of oxidative stress related genes may be a response to the formation of reactive oxygen species by a perturbation of the electron transport chain. Therefore, the formation of hydroxyl radicals and/ or peroxynitrite was monitored upon exposure to the different levels of acidity with a fluorescent probe in a flow cytometer. The formation of these oxidative compounds was shown to be specific for lethal pHs and a model to relate radical formation with the observed transcriptome profiles was proposed.
    A novel hybrid kinase is essential for regulating the σB-mediated stress response of Bacillus cereus.
    Been, M.W.H.J. de; Tempelaars, Marcel ; Schaik, W. van; Moezelaar, Roy ; Siezen, R.J. ; Abee, Tjakko - \ 2009
    Wageningen UR
    GSE14589 - Bacillus cereus - PRJNA111709 - GSE14589 - Bacillus cereus ATCC 14579 - PRJNA111709
    A common bacterial strategy for monitoring environmental challenges is to use two-component systems, which consist of a sensor histidine kinase (HK) and a response regulator (RR). In the food-borne pathogen Bacillus cereus, the alternative sigma factor σB is activated by the RR RsbY. Here we present strong indications that the PP2C-type phosphatase RsbY receives its input from the multi-sensor hybrid kinase BC1008 (renamed RsbK). Genome analyses revealed that, across bacilli, rsbY and rsbK are located in a conserved gene cluster. A B. cereus rsbK deletion strain was shown to be incapable of inducing σB upon stress conditions and was impaired in its heat adaptive response. Comparison of the wild-type and rsbK mutant transcriptomes upon heat shock revealed that RsbK was primarily involved in the activation of the σB-mediated stress response. Truncation of the RsbK RR receiver domain demonstrated the importance of
    Comparative transcriptome and phenotype analysis of acid-stressed Bacillus cereus strains
    Mols, J.M. - \ 2009
    GSE13773 - Bacillus cereus - PRJNA110781
    This SuperSeries is composed of the SubSeries listed below.
    Comparative transcriptome and phenotype analysis of acid-stressed Bacillus cereus strain ATCC 14579
    Mols, J.M. ; Kranenburg, Richard van; Melis, Clint van; Moezelaar, Roy ; Abee, Tjakko - \ 2009
    GSE13711 - Bacillus cereus - PRJNA114641
    The food-borne human pathogen Bacillus cereus is found in environments that often have a low pH, such as food and soil. The physiological response upon exposure to several levels of acidity were investigated of B. cereus model strain ATCC 14579, to elucidate the response of B. cereus to acid stress. pH 5.4, pH 5.0, pH 4.8 and pH 4.5 were selected to conduct microarray analyses, based on the differences in physiological response upon exposure to the acid conditions. The transcriptome data revealed response specific profiles. Showing mechanisms induced upon all the different acid down-shocks, such as nitrate reductase and energy production genes, and several genes specifically expressed differentially in mild or lethal levels of acidity, such as F1F0-ATPase and cydAB. Furthermore, mechanisms involved in oxidative stress response were found highly up-regulated in response to both mild and lethal acid stress. The induction of oxidative stress related genes may be a response to the formation of reactive oxygen species by a perturbation of the electron transport chain. Therefore, the formation of hydroxyl radicals and/ or peroxynitrite was monitored upon exposure to the different levels of acidity with a fluorescent probe in a flow cytometer. The formation of these oxidative compounds was shown to be specific for lethal pHs and a model to relate radical formation with the observed transcriptome profiles was proposed.
    Transcriptome analyses of 2.5% and 5% NaCl-stressed B. cereus ATCC 14579
    Besten, Heidy den; Mols, J.M. ; Moezelaar, Roy ; Zwietering, Marcel ; Abee, Tjakko - \ 2009
    GSE13713 - Bacillus cereus - PRJNA110387
    Bacteria are able to cope with the challenges of sudden increase of salinity by activating adaptation mechanisms. In this study, exponentially growing cells of the food-borne pathogen Bacillus cereus ATCC 14579 were exposed to both mild (2.5% NaCl w/v) and severe (5% NaCl w/v) salt stress conditions. B. cereus continued growth at a reduced rate when shifted to mild salt stress. Exposure to severe salt stress resulted in a lag period, and after 60 min cellular growth was resumed filamentously. Whole-genome expression analyses of cells exposed to 2.5% salt stress revealed an overlap with that of cells exposed to 5% salt stress, suggesting that the corresponding genes (n = 147) were involved in a general salt stress response. Up-regulation of osmolyte, Na+/H+ and di-/tripeptide transporters and activation of an oxidative stress response were important aspects of this general salt stress response. Activation of this response may confer cross-protection towards other stresses, and increased resistance to heat and H2O2 was indeed observed. Notably, a temporal shift was observed between the observed transcriptome and phenotype responses of severely salt-stressed cells including cellular filamentation, reduced chemotaxis performance, catalase activity and optimal oxidative stress resistance. The linkage of transcriptomes and phenotypic characteristics can contribute to a better understanding of cellular stress adaptation strategies and possible cross protection mechanisms.
    Assessment of CcpA-mediated catabolite control of metabolism and enterotoxin production in Bacillus cereus ATCC 14579
    Voort, M. van der; Kuipers, O.P. ; Buist, G. ; Vos, Willem de; Abee, Tjakko - \ 2008
    Wageningen UR
    GSE7843 - Bacillus cereus ATCC 14579 - GSE7843 - Bacillus cereus - PRJNA99971
    In Bacillus cereus the catabolite control protein CcpA was shown to be involved in optimizing the efficiency of glucose catabolism by activating genes encoding glycolytic enzymes including a non-phosphorylating glyceraldehyde-3-phosphate dehydrogenase that mediates conversion of D-glyceraldehyde 3-phosphate to 3-phospho-D-glycerate in one single step, and by repressing genes encoding the citric acid cycle and gluconeogenic enzymes. Two B. cereus-specific CcpA-regulated operons were identified, encoding enzymes involved in the catabolism of fuculose/arabinose and aspartate. In addition, a genome search using the CRE-site consensus predicted the B. cereus CcpA regulon to include 10 PTS-system gene clusters as well as genes coding for overflow metabolic enzymes leading to acetoin and acetate. Notably, catabolite repression of the genes encoding non-hemolytic enterotoxin (Nhe) and hemolytic (Hbl) enterotoxin appeared CcpA-dependent, and for the corresponding enterotoxin operons, putative CRE-sites were identified. This points to metabolic control of enterotoxin gene expression and suggests that CcpA-mediated glucose sensing provides an additional mode of control to PlcR activated expression of nhe and hbl genes in B. cereus.
    Overexpression analysis of sigZ of B. cereus ATCC 14579.
    Voort, M. van der - \ 2008
    Wageningen UR
    GSE9860 - Bacillus cereus - PRJNA103843 - GSE9860 - Bacillus cereus ATCC 14579 - PRJNA103843
    The Bacillus cereus ATCC 14579 alternative σ factor σZ and its putative regulon have been characterized. σZ shows overall similarity with ECF σ factors and sigZ constitutes an operon together with asfZ encoding its putative anti-σ factor. Expression analysis revealed sigZ to be induced by an array of stresses, including exposure to ethanol, alkaline pH and heat shock, and a typical promoter binding site for the sigZ-operon was identified by 5’RACE. Phenotypic characterization of B. cereus ATCC 14579 and its sigZ-deletion strain revealed diminished growth performance and sporulation capacity. The σZ-regulon was successfully established by transcriptome analysis of a nisin inducible sigZ-overexpression strain. Overexpression of sigZ was shown to affect expression of 42 genes, including 33 genes encoding proteins located in the extracytoplasm. The identified σZ regulon contained genes encoding proteins situated in the extracytoplasm involved in cell surface modifications and transport. The regulation of genes encoding cell surface modification proteins implies σZ to be involved in the regulation of interaction of B. cereus ATCC 14579 with its environments, which includes human intestinal cells, possibly influencing its virulence status.
    Monitoring the ethanol stress response of a sigZ deletion strain of B. cereus ATCC 14579.
    Voort, M. van der - \ 2008
    Wageningen UR
    GSE9858 - Bacillus cereus - PRJNA103839 - GSE9858 - Bacillus cereus ATCC 14579 - PRJNA103839
    The stress response of as sigZ deletion strain of B. cereus ATCC 14579 is monitored true time by use of microarrays. The sigZ regulon in ethanol stress response was determined and compared with the regulon determined by micorarray analysis of overexpression of sigZ.
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