Influence of Anaerobiosis and Low Temperature on Bacillus cereus Growth, Metabolism, and Membrane Properties

Abstract

The impact of simultaneous anaerobiosis and low temperature on growth parameters, metabolism, and membrane properties of Bacillus cereus ATCC 14579 was studied. No growth was observed under anaerobiosis at 12°C. In bioreactors, growth rates and biomass production were drastically reduced by simultaneous anaerobiosis and low temperature (15°C). The two conditions had a synergistic effect on biomass reduction. In anaerobic cultures, fermentative metabolism was modified by low temperature, with a marked reduction in ethanol production leading to a lower ability to produce NAD ؉ . Anaerobiosis reduced unsaturated fatty acids at both low optimal temperatures. In addition, simultaneous anaerobiosis and low temperatures markedly reduced levels of branched-chain fatty acids compared to all other conditions (accounting for 33% of total fatty acids against more 71% for low-temperature aerobiosis, optimal-temperature aerobiosis, and optimal-temperature anaerobiosis). This corresponded to high-melting-temperature lipids and to low-fluidity membranes, as indicated by differential scanning calorimetry, 1,6-diphenyl-1,3,5-hexatriene (DPH) fluorescence anisotropy, and infrared spectroscopy. This is in contrast to requirements for cold adaptation. A link between modification in the synthesis of metabolites of fermentative metabolism and the reduction of branchedchain fatty acids at low temperature under anaerobiosis, through a modification of the oxidizing capacity, is assumed. This link may partly explain the impact of low temperature and anaerobiosis on membrane properties and growth performance.

Beneficial effects of bio-controlling agent Bacillus cereus IB311 on the agricultural crop production and its biomass optimization through response surface methodology

“…Therefore, in the present investigation, we opt for optimization of mass production of the selected strain. Results of this study are consistent with those of previous studies, where the culture media had a significant influence on production of B. cereus (De Sarrau et al 2012, Singh et al 2013. Singh et al (2013) used response …”

Exploring the Biosynthesis of Unsaturated Fatty Acids in Bacillus cereus ATCC 14579 and Functional Characterization of Novel Acyl-Lipid Desaturases

“…We also report the functional characterization of the enzymes involved in this process. It was previously shown that B. cereus grown in different media and at different temperatures synthesized UFAs with double bonds in different positions in membrane lipids (11,12,28). In the present study, we established that in a minimal defined medium devoid of FAs, B. cereus synthesizes ⌬5, ⌬10, and ⌬5,10 UFAs.…”

“…Some psychrophilic species of Bacillus as well as B. cereus have an unusually high proportion of UFAs (8,9). Two recent studies on B. cereus strains showed that the adaptation of the membrane lipid composition of cells grown aerobically and isothermally at low temperatures was principally associated with a large increase in the proportion of UFAs (10,11). B. cereus species contain a high proportion of ⌬10 UFAs in their membrane lipids at 37°C, while at low temperatures they synthesize both ⌬10 and ⌬5 isomers (12).…”

The CasKR Two-Component System Is Required for the Growth of Mesophilic and Psychrotolerant Bacillus cereus Strains at Low Temperatures

“…For instance, membrane fatty acid (FA) composition adjustments can increase the proportion of low-meltingpoint FAs (like unsaturated FAs and branched-chain FAs) (8)(9)(10). RNA helicases that enable the RNA unfolding needed for proper translation and/or RNA degradation also play a major role in B. cereus low-temperature adaptation (11).…”