EXPRESSION OF CHITINASE-ENCODING GENES FROM AEROMONAS-HYDROPHILA AND PSEUDOMONAS-MALTOPHILIA IN BACILLUS-THURINGIENSIS SUBSP ISRAELENSIS

Fifty isolates of chitinase (Cts)-producing bacteria were collected fr om soil samples and tested for their ability to degrade chitin using c olloidal chitin agar as the primary plating medium. The results indica ted that three isolates could degrade chitin at high pH. Further studi es also demonstrated that crude Cts preparations from Bacillus circula ns (Be) No. 4.1 could enhance the toxicity of Bacillus thuringiensis s ubsp. kurstaki (Bt-k) toward diamondback moth larvae. Thus, it might b e useful to increase the toxicity of B. thuringiensis (Bt) toward targ et insects by introducing a Cts-encoding gene (cts) into Bt. To invest igate the expression of cts in Bt, cloned cts from Aeromonas hydrophil a (pHYA1) and Pseudomonas maltophilia (pHYB1, pHYB2 and pHYB3) were cl oned into the shuttle vector pHY300PLK and transformed into Escherichi a coli DH5 alpha using 4-methylumbelliferyl beta-D-N,N'-diacetylchitob ioside (4-MUF GlcNAc) as the detecting substrate. The four plasmids we re then introduced into B. thuringiensis subsp. israelensis (Bt-i) str ain c4Q272 by electroporation. Various transformants harboring cloned cts were selected, and expression and stability of the plasmids in Bt were studied.