Lipid metabolism during bacterial growth, sporulation, and germination: differential synthesis of individual branched- and normal-chain fatty acids during spore germination and outgrowth of Bacillus thuringiensis

Resistance and Raman spectroscopy analysis of Parageobacillus thermantarcticus spores after γ-ray exposure

Spores of the genus Bacillus are able to resist ionizing radiations and therefore they are a suitable biological model for studies in Astrobiology, i.e. the multidisciplinary approach to the study of the origin and evolution of life on Earth and in the universe. The resistance to γ-radiation is an important issue in Astrobiology in relation to the search for bacterial species that could adapt to life in space. This study investigates the resistance of spores of the thermophilic bacteria Parageobacillus thermantarcticus to γ-rays. The analysis of spores' response to irradiation at a molecular level is performed by means of Raman spectroscopy that allows to get insights in the sequence of events taking place during inactivation. The role of the γ-rays' dose in the inactivation of spores is also investigated, allowing to highlight the mechanism(s) of inactivation including DNA damage, protein denaturation and calcium dipicolinate levels.

Incorporation of Specific Fatty Acid Precursors During Spore Germination and Outgrowth in Bacillus thuringiensis

The selective incorporation of precursors specific for individual fatty acids in germinating and outgrowing spores of Bacillus thuringiensis is described. The specific precursors utilized were [C]butyrate, -isobutyrate, -valerate, and -isovalerate, which were incorporated into even-numbered normal-chain isomers, even-numbered iso-isomers, odd-numbered normal-chain acids, and odd-numbered isohomologs, respectively. This preferential incorporation by B. thuringiensis allows the terminal carbons of specific normal and branched-chain fatty acids, contained within the cytoplasmic membrane, to be labeled with C and, potentially, C.

Sporulation in Bacillus subtilis is independent of membrane fatty acid composition

Growth and sporulation of a Bacillus subtilis mutant deficient in branched fatty acid synthesis (gene symbol bfmB) were examined. The mutant, which produces an acyl-coenzyme A:acyl carrier protein transacylase with reduced affinity for branched fatty acid primers, could grow in media containing any one of a wide range of low-molecular-weight fatty acids having branched, cyclic, saturated, or unsaturated carbon chains. The fatty acid composition of cellular lipids depended on the compound used to support growth. Cultures of the bfmB mutant grown in the presence of 3-methylcrotonate contained an unusually high fraction (73%) of straight-chain fatty acids in the cellular lipids. The mutant sporulated with any one of the precursors of branched fatty acids in the medium; isolated spores contained mainly this branched fatty acid and only 10% or less straight-chain fatty acids regardless of the straight-chain fatty acid content of vegetative cells. Exceptional were spores grown in the presence of cyclobutane-carboxylic acid, which contained 28% straight-chain fatty acids. The branched fatty acid composition of spores could be modified greatly by changing the supply of precursors in the medium.

Production of large amounts of acetate during germination of Bacillus megaterium spores in the absence of exogenous carbon sources

When Bacillus megaterium spores germinate in the absence of an exogenous carbon source, the first minutes of germination are accompanied by production of large amounts (approximately 70 nmol/mg of dry spores) of acetate and much smaller amounts of pyruvate and lactate. The majority of these compounds are excreted into the medium. Exogenous pyruvate and alanine are also converted to CO2 and acetate by germinating spores, presumably by using the pyruvate dehydrogenase that is present in dormant spores. These data suggest that the 3-phosphoglyceric acid stores in the dormant spore and alanine generated by proteolysis early in germination can be catabolized to acetate during germination with production of large amounts of reduced nicotinamide adenine dinucleotide, acetyl coenzyme A, and adenosine 5'-triphosphate.