Properties of a Mutant of Bacillus subtilis 168 in which Spore Germination is Blocked at a Late Stage

Abstract

Summary: A mutation, gerj50, causing defective spore germination has been located between lys-1 and trpC2 on the Bacillus subtilis map and is 92% cotransduced with trpC2 by phage PBS1. Spores of strains containing gerJ50 will respond to germinants but the fall in absorbance is only 60% of that of the wild-type. During germination, mutant spores reach only an intermediate phase-grey stage, in contrast to those of the wild-type which become dark. The germination response, measured by the release of dipicolinic acid and the loss of resistance to heat, chloroform, octanol or toluene, is normal. The release of hexosamine-containing fragments from mutant spores is incomplete but has similar kinetics to that of wild-type spores. The mutant spores are more sensitive to heating at 90 °C which may point to a structural abnormality, but there is no evidence of a spore coat deficiency from electron microscopy of thin sections or freeze fractures or from the chemical resistances of the spores. Thus, the germination of mutant spores is initiated normally, but blocked at a late stage.