The potential role of a molecular chaperone on the rate of production of extensively altered "Bacillus thuringiensis Cry I C proteins was investigated. Analysis of the proteins produced by the recombinant B. thuringiensis strains showed that the truncated proteins were produced at a low rate. Expression of the 20-kDa protein gene from B. thuringiensis sp. israelensis# in tandem with the truncated-crylC genes led to the production of a greater amount of proteins. The formation of inclusion bodies, however, did not occur even when the 20-kDa protein gene was expressed.