Boonhiang PromdonkoyPatcharee PromdonkoySakol PanyimThailand National Center for Genetic Engineering and BiotechnologyMahidol University2018-06-212018-06-212005-11-01FEMS Microbiology Letters. Vol.252, No.1 (2005), 121-126037810972-s2.0-26844503739https://repository.li.mahidol.ac.th/handle/20.500.14594/16279Cry4Ba is a δ-endotoxin produced by Bacillus thuringiensis subsp. israelensis and Cyt2Aa2 is a cytolytic δ-endotoxin produced by B. thuringiensis subsp. darmstadiensis. Cry4Ba produced in Escherichia coli was toxic to Aedes aegypti larvae (LC50= 140 ng ml-1) but virtually inactive to Culex quinquefasciatus larvae. Cyt2Aa2 expressed in E. coli exhibited moderate activity against A. aegypti and C. quinquefasciatus larvae with LC50values of 350 and 250 ng ml-1, respectively. Co-expression of both toxins in E. coli dramatically increased toxicity to both A. aegypti andC. quinquefasciatus larvae (LC50= 7 and 20 ng ml-1, respectively). This is the first report to demonstrate that Cry4Ba and Cyt2Aa2 have high synergistic activity against C. quinquefasciatus larvae. © 2005 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved.Mahidol UniversityBiochemistry, Genetics and Molecular BiologyImmunology and MicrobiologyArticleSCOPUS10.1016/j.femsle.2005.08.038