A comparison of sulfhydryl active compounds on activation and germination of Bacillus thuringensis spores

Spores of Bacillus thuringiensis HD-1 and Bacillus cereus 569 were incubated in various sulfhydryl active compounds in order to compare the effects of these compounds on activation and germination. The sulfhydryl active compounds used were oxidized lipoic acid and cystine (S-S), cysteine HCl and dithiothreitol (S-H). B^. thuringiensis spores incubated in cysteine HCl had a substantially lower germination rate compared to spores incubated only in Tris pH 7.5 buffer. ^en B^. thuringiensis spores incubated in cysteine HCl were washed, they continued to exhibit this lower germination rate. Heat shocked B^. thuringiensis spores also showed a decrease in the germination rate when incubated in cysteine HCl. Comparison of B^. thuringiensis spores incubated in cysteine HCl and untreated B^. cereus spores shows the B^. thuringiensis spores decrease in germination approaching that of untreated B^. cereus spores. Heat activated spores of both B^. thuringiensis and B^. cereus had decreased germination rates when incubated in dithiothreitol compared to spores incubated in Tris pH 7.5 buffer. Heat activated B^. cereus spores incubated in lipoic acid had a lower germination rate when compared to untreated spores, while lipoic acid had no effect on heat activated B^. thuringiensis spores. These results suggest that B^. cereus and B^. thuringiensis do differ in their spore coat proteins. The action of dithiothreitol and oxidized lipoic acid were related only to heat activated spores of B^. thuringiensis and B^. cereus. The effects of cysteine HCl on B^. thuringiensis indicate a difference in disulfide bridges in the outer spore coats of B^, thuringiensis and B^. cereus.