Growth and blastospore formation by Paecilomyces fumosoroseus, a pathogen of brown planthopper ( Nilaparvata lugens)

Abstract

Paecilomyces fumosoroseus was grown in submerged culture on complex and defined media. Growth on complex medium was followed by dry weight, absorbance and ATP measurements and all methods gave similar specific growth rates (0.240–0.290 h−1). In carbon-‘limited’ cultures, the organism produced blastospores rapidly during late exponential phase and continued to form them during stationary phase; some newly-formed spores germinated during the incubation period (152 h). Blastospore yield (number of spores cm−3 culture) in batch culture was not increased when the carbon source in the medium was varied to change specific growth rate of the organism (from 0.017 to 0.224 h−1), or when the concentration of (NH4)2SO4 in the medium was varied so that it was the first nutrient to become exhausted (nitrogen-‘limited’ cultures). However, there were appreciable differences in modal volumes and glycogen and nitrogen contents of blastospores produced in nitrogen-and carbon‘limited’ cultures.