Interaction between a Bacillus cereus spore hexosaminidase and specific germinants.

A purified coat-associated hexosaminidase from spores of Bacillus cereus was studied to determine whether it could promote germination of dormant spores. Spores of a coat-deficient mutant as well as chemically extracted spores were used as substrate. Both of these spore preparations responded poorly to most germinants. However, absorbance loss was accelerated when the hexosaminidase was added in the presence of L-alanine. Enzyme alone was not effective. The addition of D-alanine inhibited completely the absorbance loss caused by hexosaminidase and L-alanine. Calcium dipicolinate and L-alpha-aminobutyric acid activated the hexosaminidase to some extent, but these chemicals were much less effective than L-alanine. In addition to the absorbance loss, the spores treated with enzyme and germinants released hexosamine and lost heat resistance and phase whiteness. The results suggest that this particular enzyme might have a role in germination.