Cloning and expression of the cryIVD gene of Bacillus thuringiensis subsp. israelensis in the cyanobacterium Agmenellum quadruplicatum PR-6 and its resulting larvicidal activity.

A mosquitocidal cyanobacterium has been developed by introducing the mosquito-toxic cryIVD gene from Bacillus thuringiensis subsp. israelensis into the unicellular cyanobacterium Agmenellum quadruplicatum PR-6 (Synechococcus sp. strain PCC 7002). The cryIVD gene was introduced into the cyanobacterium on a derivative of the PR-6 expression vector pAQE19 delta Sal in which the cryIVD gene was translationally fused to the initial coding sequence of the highly expressed PR-6 cpcB gene. Coomassie blue staining and immunoblot analysis of gel-fractionated cell extract polypeptides indicate that the cpcB-cryIVD gene fusion is expressed at high levels in the cyanobacterial cells, with little or no apparent degradation of the cryIVD gene product. Larvicidal assays revealed that freshly hatched Culex pipiens mosquito larvae readily ingested the transformed cyanobacteria and that the cells proved to be toxic to the larvae.