The Water and Solid Content of Living Bacterial Spores and Vegetative Cells as Indicated by Refractive Index Measurements

Abstract

SUMMARY: Refractive index measurements were made on the spores and vegetative cells of strains of Bacillus cereus, B. cereus var. mycoides and B. megaterium by phase contrast and interference microscopy with protein immersion. The refractive indices of the spores were found to be very high and comparable with that of dehydrated protein, suggesting that they contained very little water. Those of the vegetative cells were much lower, and indicated a solid content of about 30 %, w/v.