Cry29A and Cry30A: two novel delta-endotoxins isolated from Bacillus thuringiensis serovar medellin

Two novel crystal protein genes from a highly mosquitocidal Bacillus thuringiensis serovar medellin strain were cloned and sequenced. The corresponding proteins, Cry29A and Cry30A, were nontoxic when tested individually against the mosquito species bioassayed (Aedes aegypti, Culex pipiens and Anopheles stephensi). However, Cry29A synergized the toxicity of Cry11Bb against Aedes aegypti by a four-fold factor.     

Production of Bacillus thuringiensis subsp. medellin by batch and fed-batch culture

Bacillus thuringiensis subsp. medellin was grown until sporulation in a 1.1 l fermenter in batch and intermittent fed-batch culture. At optimum conditions 25 g dry cells l–1 and 9×108 spores ml–1 were produced. Toxicity of the final biomass showed a half lethal concentration on third instar Culex quinquefasciatus larvae of 295 ng ml–1.