Kf. Chak et al., EXPRESSION OF THE CRYSTAL PROTEIN GENE UNDER THE CONTROL OF THE ALPHA-AMYLASE PROMOTER IN BACILLUS-THURINGIENSIS STRAINS, Applied and environmental microbiology, 60(7), 1994, pp. 2304-2310
The expression of an insecticidal crystal protein gene of Bacillus thu
ringiensis under the control of the alpha-amylase gene promoter was in
vestigated. The cryIC gene, which encodes a protein known to have a un
ique activity against Spodoptera (armyworm) species, was used in this
investigation. The cryIC gene was placed, along with the alpha-amylase
promoter from B. subtilis, in a B. thuringiensis-derived cloning vect
or, generating a pair of recombinant plasmids, pSB744 and pSB745. The
cloning vector that contains the minimal replicon of B. thuringiensis
subsp. kurstaki HD73 is stably maintained in a variety of B. thuringie
nsis strains, as previously reported by Gamel and Plot (Gene 120:17-26
, 1992). The present study confirmed that the recombinant plasmids are
also stably maintained in B. thuringiensis subsp. kurstaki Cry(-)B an
d HD73 growing in media without selection pressure for at least 48 h.
The cryIC gene on the recombinant plasmids were notably expressed at h
igh levels in both recombinant strains. Expression of the introduced c
ryIC gene on the recombinant plasmid in B. thuringiensis subsp. Kursta
ki HD73 did not impair expression of the resident cryIA(c) gene. The C
ryIA(c) protein is known to have a high level of activity against loop
ers such as Trichoplusia ni (the cabbage looper). As a result of coexp
ression of the introduced cryIC gene and the resident cryIA(c) gene, r
ecombinant strain HD73 acquired an additional insecticidal activity ag
ainst Spodoptera exigua (the beet armyworm) whereas the original activ
ity level against T. ni was maintained.