Red pigment in Bacillus megaterium spores.

Bacillus megaterium QM B1551 spores contained a unique red pigment in their membranes that was not found in other species. This red pigment, presumably a carotenoid, was synthesized about the time of dipicolinic acid synthesis during sporulation and was associated with the forespores. A yellow pigment was synthesized during sporulation in rich medium and was found in the mother cell compartment. Although the yellow pigment was also associated with spores, it could be removed by two different extraction procedures without impairing germination; it was absent when sporulation occurred in a minimal medium. Although the yellow pigment of the mother cell appeared to be dispensable, the red pigment may serve a more critical function, such as membrane stabilization.

Fatty acid and phospholipid composition ofBacillus megaterium spores with altered germination properties.

The ability of spores to trigger germination was altered by growing spores at either a suboptimal temperature or in a rich medium modified by substituting L-isoleucine for D-glucose. Compared to the control, spores grown in the presence of isoleucine germinated more readily between 20 and 28 C, while spores grown at 20 C germinated slower than the control at any temperature tested. Analysis of the composition of these spores indicated that spores grown in the presence of isoleucine had much higher levels of anteiso-C15 fatty acids than the control, while the phospholipid composition and the phospholipid to protein ratio were unchanged. The fatty acid composition for spores grown at 20 C was comparable to that of the control spores, but the levels of diphosphatidylglycerol and phosphatidylglycerol were altered as well as the ratio of phospholipid to protein. Steady-state fluorescent anisotropy measurements were made with 1,6-diphenyl-1,3,5-hexatriene incorporated into membrane isolated from these spores. The membranes from spores grown in the presence of isoleucine were more "fluid" between 10 and 20 C than membranes from the control spores. Membranes from 20 C grown spores were less "fluid" between 10 and 38 C than membranes from the control spores. These results show that triggering of spore germination was altered by growing spores under conditions that altered the composition of spore membranes.