Immunological Analysis of Antigenic Variation of Bacillus thuringiensis subsp. sotto during Sporulation and Crystallization

The antigenic variation of B. thuringiensis subsp. satto have been investigated for 120 hours during sporulation and crystallization by using SDS-PAGE and Western blot. Most antigens of a vegetative cell were found to disappear as it was in sporulation and crystallization, but protein antigens of 46, 29, 27, and 21 kDa continued to be expressed. The new protein bands of 293, 138, 119, 75, and 68 kDa appeared on days 2 through 5 in modified GYS medium. They were thought to be involved in sporulation and crystallization. The protein of 138 kDa was found to be a major protein of both crystal and spore. The expression patterns were immunologically analyzed by Western blot. The polyclonal antisera against the intact crystal showed strong immunoreactivity to proteins with molecular masses of 293, 138, 68, and 46 kDa. The polyclonal antisera against the spore recognized proteins of 293, 138, 68, and 46 kDa. Both crystals and spores appeared to express the common protein antigens.