Isolation of Bacillus spp. including B. thuringiensis from apparently healthy female Aedes vexans nipponii

Abstract

Improved methods for isolation of bacteria from apparently healthy mosquitoes and for demonstration of bacterial hemolysin production are precisely described. Several hemolytic bacteria were isolated from blood-fed mosquitoes, Aedes vexans nipponii and Aedes albopictus. Among them Bacillus spp. were the predominant in Ae. vexans nipponii. No Bacillus sp. was isolated from Ae. albopictus. No hemolytic bacteria except one strain of Serratia marcescens was isolated from Ae. albopictus concomitantly captured with Ae. vexans nipponii. Bacillus spp. isolated from Ae. vexans nipponii were found to produce hemolysins which exert hemolytic activity on rabbit, sheep and mouse erythrocytes. The molecular weights of these hemolysins were instantly estimated in situ on a slab for SDS-polyacrylamide gel electrophoresis (PAGE). These bacilli might be indigenous bacteria to mosquitoes rather than transient contaminants although the number of isolated bacilli was small.