[Extraction and homogeny of larvicidal toxin in Bacillus sphaericus strain C3-41]

Spore-crystal toxin and spore-wall protein of Bacillus sphaericus C3-41 were extracted respectively from spore-crystal complex. When subjected to SDS-PAGE, spore-crystal toxin might give two toxic protein bands (43 and 40 kilodaltons), but spore-wall protein had only a protein band (MW 104 kD), which was degraded into toxic 43 and 40 kD proteins by using NaOH. The LC50 values of spore-wall protein and spore-crystal toxin purified by Sephadex G-75 were 267 and 10 ng/ml respectively against the third instar larvae of Culex quinquefasciatus at 48 hours. The results of immunodiffusion showed that sodium hydroxide-solubilized spore-crystal toxins from spore-crystal complex of strain 2362, 1593, Bs-10 (H5a5b) and 2297 (H25) revealed cross reactions with 43 and 40 kD antiserum of strain C3-41, but those of strain K (H1), SS II-1, 1404 (H2) and 2315. (H26) without cross reaction with the same antiserum.