Effect of L-cystine on macromolecular changes during spore and parasporal crystal formation in Bacillus thuringiensis var. thuringiensis.

High concentration of L-cystine (0.25%) when present in a glucose-mineral salt medium inhibited sporulation-specific events like protease production, calcium uptake and dipicolinic acid synthesis in Bacillus thuringiensis var. thuringiensis. In addition, the enzymes of the Krebs cycle from aconitase onwards were completely inhibited by a high concentration of cystine. At a low concentration of cystine (0.05%), none of the above mentioned macromolecular changes were affected. Lipid synthesis monitored by [1,214 C]-acetate incorporation into lipid as well as into whole cells was completely inhibited.