SPORULATION OF BACILLUS POPILLIAE ON SOLID MEDIA

Abstract

Spores of the insect pathogen Bacillus popilliae Dutky have been formed in vitro from vegetative cultures. The procedure results reproducibly in 0.1 to 0.3% spore formation in cells of colonies grown on a solid medium under strictly denned conditions. Sporulation requires a selected strain of the organism, NRRL B-2309S, a relatively large and specific concentration of certain yeast extracts, a specific type of agar, the complete absence of glucose, the presence of acetate, and a pH within the range 7.2 to 7.5. Spore formation occurs slowly during 2- to 4-week incubation periods in surface colonies present in limited numbers on agar plates. Some of the spores formed in this manner survive heating for 15 minutes at 80 °C, and vegetative cultures derived from such spores are pathogenic via injection for larvae of the Japanese beetle, Popillia japonica Newman.