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Bacillus cereus EntFM displays an NlpC/P60 domain, characteristic of cell wall peptidases. The protein is involved in bacterial shape, motility, adhesion to epithelial cells, biofilm formation, vacuolization of macrophages, and virulence. These data provide new information on this, so far, poorly studied toxin and suggest that this protein is a cell wall peptidase, which we propose to rename CwpFM. doi: 10.1128/JB.01315-09

Bacillus cereus 569 spores germinate either with inosine as a sole germinant or with a combination of nucleosides and L-alanine. Whereas the inosine-only germination pathway requires the presence of two different germination receptors (Gerl and GerQ) to be activated, the nucleoside/alanine germination pathway only needs one of the two receptors. To differentiate how nucleoside recognition varies between the inosine-only germination pathway and the nucleoside/ alanine germination pathway, we tested 61 purine analogues as agonists and antagonists of the two pathways in wild-type, [DELTA]gerl and [DELTA]gerQ spores. The structure-activity relationships of germination agonists and antagonists suggest that the inosine-only germination pathway is restricted to recognize a single germinant (inosine), but can be inhibited in predictable patterns by structurally distinct purine nucleosides. B. cereus spores encoding Gerl as the only nucleoside receptor ([DELTA]gerQ mutant) showed a germination inhibition profile similar to wild-type spores treated with inosine only. Thus, Gerl seems to have a well-organized binding site that recognizes inosine and inhibitors through specific substrate-protein interactions. Structure-activity analysis also showed that the nucleoside/alanine germination pathway is more promiscuous toward purine nucleoside agonists, and is only inhibited by hydrophobic analogues. B. cereus spores encoding GerQ as the only nucleoside receptor ([DELTA]gerl mutant) behaved like wild-type spores treated with inosine and L-alanine. Thus, the GerQ receptor seems to recognize substrates in a more flexible binding site through non-specific interactions. We propose that the Gerl receptor is responsible for germinant detection in the inosine-only germination pathway. On the other hand, supplementing inosine with L-alanine allows bypassing of the Gerl receptor to activate the more flexible GerQ receptor. DOI 10.1099/mic.0.030270-0

Bacillus cereus is a food-berne pathogen and a frequent contaminant of food production plants. The persistence of this pathogen in various environments results from the formation of spores and of biofilms. To investigate the role of the B. cereus flagellar apparatus in biofilm formation, we constructed a non-flagellated mutant and a flagellated but non-motile mutant. Unexpectedly, we found that the presence of flagella decreased the adhesion of the bacterium to g ass surfaces. We hypothesize that this decrease is a consequence of the flagella hindering a direct interaction between the bacterial cell wall and the surface. In contrast, in specific conditions, motility promotes biofilm formation. Our results suggest that motility could influence biofilm formation by three mechanisms. Motility is necessary for the bacteria to reach surfaces suitable for biofilm formation, In static conditions, reaching the air--liquid interface, where the biofilm forms, is a strong requirement, whereas in flow cells bacteria can have access to the bosom glass slide by sedimentation. Therefore, motility is important for biofilm formation in glass tubes and in microtitre plates, but not in flew cells. Motility also promotes recruitment of planktonic cells within the biofilm by allowing motile bacteria to invade the whole biofilm, Finally, motility is involved in the spreading of the biofilm on glass surfaces. DOI 10.1099/mic.0.034827-0

The virulence of Bacillus cereus requires that bacteria have the capacity to colonize their host, degrade specific tissues, and circumvent the host immune system. To study this aspect of pathogenesis, we focused on three metalioproteases, InhA1, InhA2, and InhA3, which share more than 66% identity. The expression of these metalloprotease genes was assessed by transcriptional fusions with a lacZ reporter gene. The expression profiles suggest a complementary time course of InhA production. Indeed, the genes are simultaneously expressed but are oppositely controlled during stationary phase. We constructed single and multiple inhA mutants and assessed the bacterial locations of the proteins as well as their individual or additive roles in macrophage escape and toxicity, antibacterial-peptide cleavage, and virulence. InhA1, a major component of the spore exosporium, is the only InhA metalloprotease involved in bacterial escape from macrophages. A mutant lacking inhA1, inhA2, and inhA3 shows a strong decrease in the level of virulence for insects. Taken together, these results show that the InhA metalloproteases of B. cereus are important virulence factors that may allow the bacteria to counteract the host immune system. doi: 10.1128/JB.00264-09

Silicon (Si) is considered to be a 'quasiessential' element for most living organisms. However, silicate uptake in bacteria and its physiological functions have remained obscure. We observed that Si is deposited in a spore coat layer of nanometer-sized particles in Bacillus cereus and that the Si layer enhances acid resistance. The novel acid resistance of the spore mediated by Si encapsulation was also observed in other Bacillus strains, representing a general adaptation enhancing survival under acidic conditions. doi: 10.1128/JB.00954-09

The function of orf4 in the sigB cluster in Bacillus cereus ATCC 14579 remains to be explored. Amino-acid sequence analysis has revealed that Orf4 is homologous with bacterioferritins and Dps. In this study, we generated an orf4-null mutant and produced recombinant protein rOrf4 to establish the role of orf4. In vitro, the purified rOrf4 was found to exist in two distinct forms, a dimeric form and a polymer form, through size exclusion analysis. The latter form exhibited a unique filament structure, in contrast to the typical spherical tetracosamer structure of bacterioferritins; the former can be induced to form rOrf4 polymers immediately after the addition of Fe[Cl.sub.2]. Catalysis of the oxidation of ferrous irons by ferroxidase activity was detected with rOrf4, and the mineralized irons were subsequently sequestered only in the rOrf4 polymer. Moreover, rOrf4 exerted DNA-protective activity against oxidative damage via DNA binding in a nonspecific manner, as is seen with Dps. In vivo, deletion of orf4 had no effect on activation of the alternative sigma factor [[sigma].sup.B], and therefore, orf4 is not associated with [[sigma].sup.B] regulation; however, orf4 can be significantly upregulated upon environmental stress but not [H.sub.2][O.sub.2] treatment. B. cereus strains with constitutive Orf4 expression exhibited a viability higher than that of the orf4-null mutant, under specific oxidative stress or heat shock. Taken together, these results suggest that Orf4 functions as a Dps-like bacterioferritin in response to environmental stress and can provide cell protection from oxidative damage through iron sequestration and DNA binding.

In the food-borne pathogen Bacillus cereus F4430/73, the production of major virulence factors hemolysin BL (Hbl) and nonhemolytic enterotoxin (Nhe) is regulated through complex mechanisms. The two-component regulatory system ResDE is involved in the activation of hbl and nhe transcription. Here, the response regulator ResD and the sensor kinase ResE were overexpressed and purified, and autophosphorylation of ResE and transphosphorylation of ResD by ResE were demonstrated in vitro. ResD is mainly monomeric in solution, regardless of its phosphorylation state. ResD was shown to interact directly with promoter regions (p) of the enterotoxin regulator genes resDE, fnr, and plcR and the enterotoxin structural genes nhe and hbl, but with different affinities. Binding of ResD to pplcR, pnhe, and phbl was not dependent on the ResD phosphorylation status. In contrast, ResD phosphorylation significantly increased interactions between ResD and presDE and pfnr. Taken together, these results showed that phosphorylation of ResD results in a different target expression pattern. Furthermore, ResD and the redox activator Fnr were found to physically interact and simultaneously bind their target DNAs. We propose that unphosphorylated ResD acts as an antiactivator of Fnr, while phosphorylated ResD acts as a coactivator of Fnr. Finally, our findings represent the first molecular evidence of the role of ResDE as a sentinel system capable of sensing redox changes and coordinating a response that modulates B. cereus virulence.

Several Baciflus strains isolated from commercial probiotic preparations were identified at the species level, and their adhesion capabilities to three different model intestinal surfaces (mucin, Matrigel and Caco-2 cells) were assessed. In general, adhesion of spores was higher than that of vegetative cells to the three matrices, and overall strain Bacillus [cereus.sub.CH] displayed the best adhesion. Different biochemical treatments revealed that surface proteins of B. [cereus.sub.CH] were involved in the adhesion properties of the strain. Surface-associated proteins from vegetative cells and spores of B. [cereus.sub.CH] were extracted and identified, and some proteins such as S-layer components, flagellin and cell-bound proteases were found to bind to mucin or fibronectin. These facts suggest that those proteins might play important roles in the interaction of this probiotic Bacillus strain within the human gastrointestinal tract.

The GerT protein of Bacillus cereus shares 74% amino acid identity with its homolog GerN. The latter is a [Na.sup.+]/[H.sup.+]-[K.sup.+] antiporter that is required for normal spore germination in inosine. The germination properties of single and double mutants of B. cereus ATCC 10876 reveal that unlike GerN, which is required for all germination responses that involve the GerI germinant receptor, the GerT protein does not have a significant role in germination, although it is required for the residual GerI-mediated inosine germination response of a gerN mutant. In contrast, GerT has a significant role in outgrowth; gerT mutant spores do not outgrow efficiently under alkaline conditions and outgrow more slowly than the wild type in the presence of high NaCl concentrations. The GerT protein in B. cereus therefore contributes to the success of spore outgrowth from the germinated state during alkaline or [Na.sup.+] stress.

The mechanism by which Bacillus cereus causes diarrhoea is unknown. Three putative enterotoxins have been proposed, haemolysin BL (Hbl), cytotoxin K and non-haemolytic enterotoxin (Nhe). Both Hbl and Nhe are three-component cytotoxins and maximal cytotoxicity of Nhe against epithelia is dependent on all three components. However, little is known of the mechanism of cytotoxicity. Markers of plasma membrane disruption, namely propidium iodide uptake, loss of cellular ATP and release of lactate dehydrogenase (LDH), were observed in epithelia exposed to Nhe from culture supernatants of B. cereus, but not in those exposed to supernatants from a mutant strain lacking NheB and NheC. Consistent with an exogenous cause of membrane damage, purified Nhe components combined to form large conductance pores in planar lipid bilayers. The inhibition of LDH release by osmotic protectants and the increase in cell size caused by Nhe indicate that epithelia lyse following osmotic swelling. Nhe and Hbl show sequence homology, and Hbl component B has remarkable structural similarities to cytolysin A (ClyA), with both structures possessing an a-helix bundle and a unique subdomain containing a hydrophobic [beta]-hairpin. Correspondingly, we show that Nhe has haemolytic activity against erythrocytes from a variety of species. We propose that the common structural and functional properties indicate that the Hbl/Nhe and ClyA families of toxins constitute a superfamily of pore-forming cytotoxins.

Members of the Bacillus cereus group contain cell wall carbohydrates that vary in their glycosyl compositions. Recent multilocus sequence typing (MLST) refined the relatedness of B. cereus group members by separating them into clades and lineages. Based on MLST, we selected several B. anthracis, B. cereus, and B. thuringiensis strains and compared their cell wall carbohydrates. The cell walls of different B. anthracis strains (clade l/Anthracis) were composed of glucose (Glc), galactose (Gal), N-acetyl mannosamine (ManNAc), and Nacetylglucosamine (GlcNAc). In contrast, the cell walls from clade 2 strains (B. cereus type strain ATCC 14579 and B. thuringiensis strains) lacked Gal and contained N-acetylgalactosamine (GalNAc). The B. cereus clade 1 strains had cell walls that were similar in composition to B. anthracis in that they all contained Gal. However, the cell walls from some clade 1 strains also contained GalNAc, which was not present in B. anthracis cell walls. Three recently identified clade 1 strains of B. cereus that caused severe pneumonia, i.e., strains 03BB102, 03BB87, and G9241, had cell wall compositions that closely resembled those of the B. anthracis strains. It was also observed that B. anthracis strains cell wall glycosyl compositions differed from one another in a plasmid- dependent manner. When plasmid pXO2 was absent, the ManNAc/Gal ratio decreased, while the Glc/Gal ratio increased. Also, deletion of atxA, a global regulatory gene, from a pXO2- strain resulted in cell walls with an even greater level of Glc.

Various assays and culture conditions and a range of strains used to study the roles of strain diversity and environmental conditions showed that Bacillus cereus biofilms could act as a nidus for spore formation and subsequently release their spores into food production environments.

The exosporium-defective phenotype of a transposon insertion mutant of Bacillus cereus implicated ExsY, a homologue of B. subtilis cysteine-rich spore coat proteins CotY and CotZ, in assembly of an intact exosporium. Single and double mutants of B. cereus lacking ExsY and its paralogue, CotY, were constructed. The exsY mutant spores are not surrounded by an intact exosporium, though they often carry attached exosporium fragments. In contrast, the cotY mutant spores have an intact exosporium, although its overall shape is altered. The single mutants show altered, but different, spore coat properties. The exsY mutant spore coat is permeable to lysozyme, whereas the cotY mutant spores are less resistant to several organic solvents than is the case for the wild type. The exsY cotY double-mutant spores lack exosporium and have very thin coats that are permeable to lysozyme and are sensitive to chloroform, toluene, and phenol. These spore coat as well as exosporium defects suggest that ExsY and CotY are important to correct formation of both the exosporium and the spore coat in B. cereus. Both ExsY and CotY proteins were detected in Western blots of purified wild-type exosporium, in complexes of high molecular weight, and as monomers. Both exsY and cotY genes are expressed at late stages of sporulation.

Members of the Bacillus cereus group are ubiquitously present in the environment and can adapt to a wide range of environmental fluctuations. In bacteria, these adaptive responses are generally mediated by two-component signal transduction systems (TCSs), which consist of a histidine kinase (HK) and its cognate response regulator (RR). With the use of in silico techniques, a complete set of HKs and RRs was recovered from eight completely sequenced B. cereus group genomes. By applying a bidirectional best-hits method combined with gene neighbourhood analysis, a footprint of these proteins was made. Around 40 HK-RR gene pairs were detected in each member of the B. cereus group. In addition, each member contained many HK and RR genes not encoded in pairs ('orphans'). Classification of HKs and RRs based on their enzymic domains together with the analysis of two neighbour-joining trees of these domains revealed putative interaction partners for most of the 'orphans'. Putative biological functions, including involvement in virulence and host--microbe interactions, were predicted for the B. cereus group HKs and RRs by comparing them with those of B. subtilis and other micro-organisms. Remarkably, B. anthracis appeared to lack specific HKs and RRs and was found to contain many truncated, putatively nonfunctional, HK and RR genes. It is hypothesized that specialization of B. anthracis as a pathogen could have reduced the range of environmental stimuli to which it is exposed. This may have rendered some of its TCSs obsolete, ultimately resulting in the deletion of some HK and RR genes.

The alternative sigma factor [[sigma].sup.B] of the food pathogen Bacillus cereus is activated upon stress exposure and plays a role in the adaptive response of vegetative cells. This study describes the identification of [[sigma].sup.B]-dependent genes in B. cereus. Two-dimensional gel electrophoresis was performed with protein extracts from a [[sigma].sup.B]-overproducing B. cereus strain. Nine protein spots, which were absent from the negative control, were identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry or N-terminal sequencing. The [[sigma].sup.B]-dependent expression of the corresponding genes was confirmed by Northern blot analysis with RNA isolated from B. cereus ATCC 14579 and its sigB null mutant. Northern blot analysis also revealed that six other genes were part of [[sigma].sup.B]-dependent operons. The proteins that are predicted to be encoded by the [[sigma].sup.B]-dependent genes include an intracellular protease, a [Mg.sup.2+] transporter, and a thiamine biosynthesis protein (ThiG). Highly conserved promoter sites were found to precede all [[sigma].sup.B]-dependent genes, with the exception of thiG. By searching the B. cereus genome for this conserved promoter sequence, five more candidate [[sigma].sup.B]-dependent genes were identified. Northern blot analysis and in vitro transcription experiments with a reconstituted B. cereus [[sigma].sup.B]-RNA polymerase holoenzyme confirmed the [[sigma].sup.B] dependency of two of these genes and strongly suggested that two other genes, encoding an oligopeptide-binding OppA-like protein and subunit II of the cytochrome d ubiquinol oxidase, are also [[sigma].sup.B] dependent. In conclusion, [[sigma].sup.B] of B. cereus not only regulates genes directly involved in the stress response but may also control specific metabolic rearrangements.

Bacillus thuringiensis, Bacillus cereus, and Bacillus anthracis are closely related species belonging to the Bacillus cereus group. B. thuringiensis and B. cereus generally produce extracellular proteins, including phospholipases and hemolysins. Transcription of the genes encoding these factors is controlled by the pleiotropic regulator PlcR. Disruption of plcR in B. cereus and B. thuringiensis drastically reduces the hemolytic, lecithinase, and cytotoxic properties of these organisms. B. anthracis does not produce these proteins due to a nonsense mutation in the plcR gene. We screened 400 B. thuringiensis and B. cereus strains for their hemolytic and lecithinase properties. Eight [Hly.sup.-] [Lec.sup.-] strains were selected and analyzed to determine whether this unusual phenotype was due to a mutation similar to that found in B. anthracis. Sequence analysis of the DNA region including the plcR and papR genes of these strains and genetic complementation of the strains with functional copies of plcR and papR indicated that different types of mutations were responsible for these phenotypes. We also found that the plcR genes of three B. anthracis strains belonging to different phylogenetic groups contained the same nonsense mutation, suggesting that this mutation is a distinctive trait of this species.

Bam35, a 15-kbp double-stranded DNA phage, infects Bacillus thuringiensis. Recently, sequencing of the related Bacillus cereus revealed a 15.1-kbp linear plasmid, pBClin15. We show that pBClin15 closely resembles Bam35 and demonstrate conversion of Bam35 to a prophage. This state is common, as several B. thuringiensis strains release Bam35-related viruses.

Research has been conducted on the Bacillus cereus germination protein GerN. Results indicate that the Escherichia coli mutants have been transformed with a plasmid that expressed B. cereus gerN and that the activity of this putative transport protein has been examined.

Results show that Bacillus cereus grows and sporulates despite inactivation of the gerN gene, which controls growth and sporulation. Data indicate that the requirement of a particular germinant by GerN suggests germination receptor's association with an antiporter that initiates germination.

Research reveals that haemolysin BL toxin belongs to a family of multicomponent toxins evolved by gene and operon duplication at the intracellular or horizontal genetic transfer levels. Results indicate that two distinct homologous sets of the toxin exist in Bacillus cereus isolate MGBC 145.

HBL, a hemolytic enterotoxin, is broadly distributed in Bacillus cereus group species regardless of environment. The prevalence was determined in all species other than B. anthracis. PCR and Southern analysis were used with confirmation by partial sequencing of 18 strains. Consequences for food safety should be considered.

Results describe the organization and order of the genes in the mercury resistance determinant and identification of two new transcription open reading frames between merA and merB genes. The differences in the functional activity and inducibility of the determinant in Bacillus cereus RC607, in relation to other bacteria, are presented.

Monoclonal antibodies against the hemolysin BL (HBL) enterotoxin complex from Bacillus cereus are discussed relative to production and characterization. Five hybridoma cell lines that produced the antibodies were established and studied. An effort was made to achieve monoclonal antibodies that would improve specific detection of the components of HBL and be effective in the screening of B. cereus isolates for enterotoxic activity.

Research was conducted to examine the cellular mechanisms leading to morphological shifts, growth inhibition and lysis of Bacillus cereus WSBC 10030 when challenged with a long-chain polyphosphate (polyP). The objective was to analyze the mechanism of polyP inhibition in greater detail. Results indicate that polyP indirectly influences the general division mechanism of cells, the Fts protein family.

An examination of the responses of Bacillus cereus to increasing quantities of agar was conducted. Of special concern were the influence of structural properties and kinetic constraints on the behavior of the species. Bacterial colonies responded to nutrient gradients by decreasing in size the farther they were from the nutrient source. The agar content influenced the decrease in colony size. The agar gel architecture did not affect the diffusivities of glucose and a protein, indicating that mechanical factors as well as other factors can influence microbial growth in the agar systems used.

In the guts of more than 25 species of arthropods we observed filaments containing refractile inclusions previously discovered and named 'Arthromitus' in 1849 by Joseph Leidy [Leidy, J. (1849) Proc. Acad. Nat. Sci. Philadelphia 4, 225-233]. We cultivated these microbes from boiled intestines of 10 different species of surface-cleaned soil insects and isopod crustaceans. Literature review and these observations lead us to conclude that Arthromitus are spore-forming, variably motile, cultivable bacilli. As long rod-shaped bacteria, they lose their flagella, attach by fibers or fuzz to the intestinal epithelium, grow filamentously, and sporulate from their distal ends. When these organisms are incubated in culture, their life history stages are accelerated by light and inhibited by anoxia. Characterization of new Arthromitus isolates from digestive tracts of common sow bugs (Porcellio scaber), roaches (Gromphodorhina portentosa, Blaberus giganteus) and termites (Cryptotermes brevis, Kalotermes flavicollis) identifies these flagellated, spore-forming symbionts as a Bacillus sp. Complete sequencing of the 16S rRNA gene from four isolates (two sow bug, one hissing roach, one death's head roach) confirms these as the low-G+C Gram-positive eubacterium Bacillus cereus. We suggest that B. cereus and its close relatives, easily isolated from soil and grown on nutrient agar, enjoy filamentous growth in moist nutrient-rich intestines of healthy arthropods and similar habitats.

The growth of four strains of psychotropic Bacillus cereus strains were cultured in a brain heart infusion (BHI) broth and beef gravy with nisin supplementation. The repair of cytoplasmic membrane dysfunction in heat injured Bacillus cereus cells was inhibited by nisin which acted as a voltage-dependent polarizer that prevented the restoration of membrane integrity. The growth and enterotoxin synthesis by Bacillus cereus in BHI was also attenuated by nisin compared to microbial cultures in beef gravy.

Absolute fluorescence cross sections for Bacillus subtilis and B. cereus bacterial spores as both aqueous suspensions and aerosols were measured at a number of excitation wavelengths between 228 and 303 nm. The fluorescence was spectrally resolved at each excitation wavelength. We found that the optimum excitation wavelength for spore fluorescence is between 270 and 280 nm. The fluorescence cross section for aqueous suspensions is four times larger than for dry aerosols when measured under similar conditions. Measurements on wet aerosols showed an increase in fluorescence cross section over dry aerosols, indicating an enhancement of the fluorescence when the bacterial spores are wet. Mie scattering cross sections at 90 [degrees] to the direction of the incident radiation and extinction cross sections as a function of wavelength for B. subtilis suspensions and fluorescence cross sections for tryptophan are also reported.

A Bacillus cereus UW85-produced antibiotic, Kanosamine, is inhibitory to the growth of plant-pathogenic oomycetes and to certain fungi. The production of kanosamine is inhibited by phosphate and facilitated by ferric iron and alfalfa seeding exudate. The accumulation of kanosamine in the Bacillus cereus UW85 is associated with sporulation. Production of kanosamine is regulated by plant factors. Its structure is identified as 3-amino-3-deoxy-D-glucose.

Bacillus cereus UW85 produces two fungistatic antibiotics zwittermicin A and antibiotic B that suppress the damping-off disease of alfalfa seedlings. The disease inhibition is proportional to the amount of antibiotics accumulated, with antibiotic B eliminating germ tube swelling and zwittermicin preventing germ tube elongation.

The effects of maltodextrin on the synthesis of eneterotoxin and the growth of Bacillus cereus in reconstituted infant milk-based formulae (IMF) were analyzed to determine the mechanisms of diarrheal-type food intoxication. Analysis of IMF from leading baby food companies indicated the role of maltodextrin in enhancing the synthesis of diarrheal enterotoxin by different strains of Bacillus cereus. Furthermore, maltodextrin promotes the growth of diarrheagenic Bacillus cereus in IMF.

The role of the five putative RNA helicases present in the genome of Bacillus cereus ATCC 14579 in its adaptation at low temperature, close to the growth limit is examined. The studies have shown that cold phenotype is restored with the cshA gene for the [DELTA]cshA strain and partially for the [DELTA]cshB strain but not for the [DELTA]cshC strain, which has shown different functions at low temperature.

The quantification of hurdle technology has identified synergistic or multiplicative effects and the validity of the gamma hypothesis is tested with respect to the use of pH and various concentrations of undissociated acids to control growth of Bacillus cereus in brain heart infusion broth. The studies have shown that the introduction of synergy factors into the models have not improved the quality of the prediction, but have led to the overestimation of the growth boundary.

A study was conducted to analyze the physiological and genome-wide transcriptional responses of Bacillus cereus ATCC 14579 exposed to four different disinfectants like benzalkonium chloride, sodium hypochloride, hydrogen peroxide and peracetic acid. The exposures to hydrogen peroxide and peracetic acid was found to induce highly similar responses, including the upregulation of genes involved in DNA damage repair and SOS response.

A recombinase-based in vivo expression technology (IVET) was adapted to study the genes activated in Bacillus cereus ATCC 14579 during growth at low temperatures. The study demonstrated the feasibility of a promoter trap strategy for identifying cold-induced genes and also outlined the different processes involved in B. cereus cold acclimation.

The ability of the profiling of cellular fatty acid methyl ester (FAME) to discriminate between the different samples of Bacillus cereus T-strain spores grown on different media is determined. FAME profiling is shown to be extremely useful for the demarcation and can even be employed for analyzing the production methods of the species.

The spore morphology, hydrophobic characteristics and net negative charge of food-borne and food poisoning-associated isolates of the Bacillus cereus group are examined including the enterotoxigenic Bacillus thuringiensis. The characteristics have shown that spores of food-associated Bacillus thuringiensis and not only Bacillus cereus sensu stricto have high potential to hold on to inert surfaces.

A complete transcriptional analysis of the ces gene cluster is conducted by using reverse transcription-PCR (RT-PCR), rapid amplification of cDNA ends (RACE) and promoter deletion analysis in order to identify the promoters from the emetic reference strain Bacillus cereus F4810/72 and characterize the ces transcripts. The amount of cereulide toxin extracted from spiked foods has correlated well with the bioluminescence data, thus highlighting the potential of the reporter system for monitoring ces gene expression in complex matrices.

Several studies are conducted to explain the classification and the sequence and length polymorphisms of the various bcl genes and proteins of the organisms belonging to the Bacillus cereus group. A new approach that can be used for an effective detection of these genes is also presented.

A study was conducted to determine the biofilm formation by 102 Bacillus cereus and B. thuringiensis strains and examine the cell surface hydrophobicity, the presence of an S layer, and adhesion to epithelial cells. Strains isolated from soil or involved in digestive tract infections are found to be efficient biofilm formers while strains isolated from other diseases were poor biofilm formers.

The analyses of the exponentially growing cells of the pathogen Bacillus cereus ATCC 14579 exposed to both mild and severe salt stress conditions are presented. The linkage transcriptomes and phenotypic characteristics have helped in understanding the cellular stress adaptation strategies and cross-protection mechanisms.

The identification of the complete zwittermicin A (ZmA) biosynthesis gene cluster from Bacillus cereus UW85 is presented. The bioinformatics and biochemical analyses of the ZmA biosynthesis enzymes revealed that ZmA is biosynthesized in an unusual manner that involves processing in both its N and C termini resulting in the formation of ZmA and two additional metabolites.

Spores isolated from Bacillus cereus ATCC 14579 and mutant strains lacking each of seven germinant receptor operons were exposed to differentiated Caco-2 cells and monitored for germination. A reduced germination response exhibited by spores of the gerI and gerL mutants point to significant role of germinant receptors in Caco-2-induced germination.

The germination induction upon adhesion to caco-2 cells in 11 enterotoxigenic strains of Bacillus cereus was investigated. It was found that spores of the 11 strains of Bacillus cereus adhered with similar efficiencies to Caco-2 cells, Hep-2 cells did not trigger germination and spores of all strains displayed similar germination efficiencies.

A quantitative analysis of population heterogeneity of the adaptive salt stress response and growth capacity of Bacillus cereus ATCC 14579 was conducted. It was found that exposure to mild salt stress resulted in growth characterized by a remarkably low variability of microcolony sizes and under severe salt stress conditions, the microcolony sizes were highly heterogeneous.

A novel 5' nuclease (TaqMan) real-time PCR assay is developed in order provide a rapid and sensitive method for the specific detection of emetic Bacillus cereus in food. The developed assays could contribute substantially to determining the true incidence of the emetic type of food poisoning caused by Bacillus cereus, especially by reducing the rate of misdiagnosis.

The quantification of the effects of salt stress response on thermal inactivation kinetics for exponential-, transition- , and stationary-phase cells of the two Bacillus cereus strains, ATCC 10987 and ATCC 14579 was performed. It was observed that the strain diversity greatly influenced the thermotolerance and survival curvatures and the maximum adaptive salt stress response in exponential-phase was comparable to the physiological state on thermotolerance.

Phylogenetic relationships for a collection of Bacillus cereus group strains isolated from forest soil in the Paris area during a mild winter is characterized with the use of multilocus sequence typing (MLST). The analysis of Bacillus cereus and Bacillus thuringiensis reveals separate clustering and a distinct population structure of psychrotrophic strains, and that they have clonal population structures.

Cell-free supernatants from growing Bacillus cereus strain ATCC 10987 induced luminescence in a Photorhabdus luminescens (delta)luxS mutant, indicating the production of functional auto inducer 2(AI-2). It was observed that AI-2 had an inhibitory effect on biofilm formation by B. cereus and promoted release of the cells from a performed biofilm.