Involvement of the CasK/R two-component system in optimal unsaturation of the Bacillus cereus fatty acids during low-temperature growth

Diomandé, Sara Esther; Nguyen-Thé, Christophe; Abee, Tjakko; Tempelaars, Marcel H.; Broussolle, Véronique; Brillard, Julien

doi:10.1016/j.ijfoodmicro.2015.04.043

Cited by 13 publications

(10 citation statements)

References 52 publications

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“…In contrast to the membrane protein DesK, CasK presumably has a cytoplasmic location ( Diomandé et al, 2014 ). Recent evidence has shown that this TCS regulates genes involved in both FA synthesis and FA degradation ( Diomandé et al, 2015a ), including two genes encoding the desaturases desA and desB in B. cereus. During growth at low temperatures, CasK/R regulates the membrane FA composition and, mainly, UFA synthesis by regulating desA .…”

Section: Nature and Synthesis Of The Main Fas In The Bacillmentioning

confidence: 99%

“…In B. cereus , an exogenous source of UFAs was shown to improve the growth of the casK/R mutant ( Diomandé et al, 2015a ). This mutant displayed a decreased proportion of UFAs during growth at low temperatures compared to the parental strain, and an exogenous source of UFAs provided support to membrane-level modifications caused by the mutation.…”

Section: Exogenous Fas: Their Impact On Bacillus Gmentioning

confidence: 99%

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Role of fatty acids in Bacillus environmental adaptation

et al. 2015

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The large bacterial genus Bacillus is widely distributed in the environment and is able to colonize highly diverse niches. Some Bacillus species harbor pathogenic characteristics. The fatty acid (FA) composition is among the essential criteria used to define Bacillus species. Some elements of the FA pattern composition are common to Bacillus species, whereas others are specific and can be categorized in relation to the ecological niches of the species. Bacillus species are able to modify their FA patterns to adapt to a wide range of environmental changes, including changes in the growth medium, temperature, food processing conditions, and pH. Like many other Gram-positive bacteria, Bacillus strains display a well-defined FA synthesis II system that is equilibrated with a FA degradation pathway and regulated to efficiently respond to the needs of the cell. Like endogenous FAs, exogenous FAs may positively or negatively affect the survival of Bacillus vegetative cells and the spore germination ability in a given environment. Some of these exogenous FAs may provide a powerful strategy for preserving food against contamination by the Bacillus pathogenic strains responsible for foodborne illness.

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Section: Nature and Synthesis Of The Main Fas In The Bacillmentioning

confidence: 99%

Section: Exogenous Fas: Their Impact On Bacillus Gmentioning

confidence: 99%

Role of fatty acids in Bacillus environmental adaptation

et al. 2015

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“…In the case of bacteria grown in liquid media, the bacterial biomass is collected by centrifugation of the growth medium and can be washed according to previously described protocols depending on the growth conditions 8,19 . The identification of the various FAs produced by B. cereus permitted fine changes in the proportion of the FAs to be detected in strains mutated on some genes necessary for growth at low temperature 7,9 .…”

Section: Discussionmentioning

confidence: 99%

Identification of Fatty Acids in <em>Bacillus cereus</em>

Giniès¹,

Brillard²,

Nguyen-Thé³

2016

JoVE

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The Bacillus species contain branched chain and unsaturated fatty acids (FAs) with diverse positions of the methyl branch (iso or anteiso) and of the double bond. Changes in FA composition play a crucial role in the adaptation of bacteria to their environment. These modifications entail a change in the ratio of iso versus anteiso branched FAs, and in the proportion of unsaturated FAs relative to saturated FAs, with double bonds created at specific positions. Precise identification of the FA profile is necessary to understand the adaptation mechanisms of Bacillus species. Many of the FAs from Bacillus are not commercially available. The strategy proposed herein identifies FAs by combining information on the retention time (by calculation of the equivalent chain length (ECL)) with the mass spectra of three types of FA derivatives: fatty acid methyl esters (FAMEs), 4,4-dimethyl oxazoline derivatives (DMOX), and 3-pyridylcarbinyl ester (picolinyl). This method can identify the FAs without the need to purify the unknown FAs. Comparing chromatographic profiles of FAME prepared from Bacillus cereus with a commercial mixture of standards allows for the identification of straight-chain saturated FAs, the calculation of the ECL, and hypotheses on the identity of the other FAs. FAMEs of branched saturated FAs, iso or anteiso, display a constant negative shift in the ECL, compared to linear saturated FAs with the same number of carbons. FAMEs of unsaturated FAs can be detected by the mass of their molecular ions, and result in a positive shift in the ECL compared to the corresponding saturated FAs. The branching position of FAs and the double bond position of unsaturated FAs can be identified by the electron ionization mass spectra of picolinyl and DMOX derivatives, respectively. This approach identifies all the unknown saturated branched FAs, unsaturated straight-chain FAs and unsaturated branched FAs from the B. cereus extract.

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“…Transcriptomic analysis of the ΔcasKR mutant revealed that desA and desB genes, encoding DesA and DesB acyl-lipid desaturases, were downregulated in this strain. This mutant showed lower Δ5 UFA content compared with the parental strain, which could be responsible for its cold-sensitive phenotype (Diomandé et al 2015). Although cold induction of desA transcription is dependent on the CasKR system, CasR does not interact in vitro with the desA promoter, suggesting that the regulation is indirect (Diomandé et al 2016).…”

Section: Caskr Regulates Optimal Unsaturation Of B Cereus Fatty Acidsmentioning

confidence: 95%

Regulation of Membrane Lipid Homeostasis in Bacteria upon Temperature Change

Mansilla¹,

Mendoza²

2016

Biogenesis of Fatty Acids, Lipids and Membranes

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Bacteria precisely remodel the fluidity of their membrane bilayer via the incorporation of proportionally more unsaturated fatty acids (or fatty acids with analogous properties, such as branched-chain fatty acids) as growth temperature decreases. This process, termed homeoviscous adaptation, is suited to disrupt the order of the lipid bilayer and optimizes the performance of a large array of cellular physiological processes at the new temperature. As such, microbes have developed molecular strategies to sense changes in membrane fluidity, provoked by a decrease in environmental temperature, and initiate cellular responses that

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Involvement of the CasK/R two-component system in optimal unsaturation of the Bacillus cereus fatty acids during low-temperature growth

Cited by 13 publications

References 52 publications

Role of fatty acids in Bacillus environmental adaptation

Role of fatty acids in Bacillus environmental adaptation

Identification of Fatty Acids in <em>Bacillus cereus</em>

Regulation of Membrane Lipid Homeostasis in Bacteria upon Temperature Change

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