Lipid metabolism during bacterial growth, sporulation, and germination: kinetics of fatty acid and macromolecular synthesis during spore germination and outgrowth of Bacillus thuringiensis

The timing and kinetics of fatty acid synthesis are delineated for B. thuringiensis spore germination and outgrowth by analyzing [U-¹⁴C] acetate and [2-³H]glycerol incorporation into chloroform methanol extractable and trichloroacetic acid precipitable lipids. In addition to measurement of pulsed and continuous labeling of fatty acids, monitoring the incorporation of radioactive phenylalanine, thymidine, and uridine from the onset of germination through first cell division provides a profile of biochemical activities related to membrane differentiation and cellular development. Upon germination, ribonucleic acid synthesis is initiated, immediately followed by rapid and extensive fatty acid synthesis that in turn precedes protein, deoxyribonucleic acid and triglyceride synthesis. Significantly, formation of fatty acids from acetate exhibits further developmental periodicity in which a large transient increase in fatty acid synthetic activity coincides with the approach of cell division. Radiorespirometric analyses indicate only slight oxidative decarboxylation of acetate and corroborates the extreme involvement of acetate in specific fatty acid biosynthetic reactions throughout cellular modification. These findings graphically demonstrate an intimate association of fatty acid metabolism with commitment to spore outgrowth and subsequent cell division.