Submitted to: Biocontrol Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 29, 2002
Publication Date: June 1, 2003
Citation: JACKSON, M.A., CLIQUET, S., ITEN, L.B. MEDIA AND FERMENTATION PROCESSES FOR THE RAPID PRODUCTION OF HIGH CONCENTRATIONS OF STABLE BLASTOSPORES OF THE BIOINSECTICIDAL FUNGUS PAECILOMYCES FUMOSOROSEUS. BIOCONTROL SCIENCE AND TECHNOLOGY. 2003. v. 13. p. 23-33. Interpretive Summary: The commercial use of living microbial biocontrol agents, weed, insect, or plant disease control, requires that low-cost methods be developed for producing and stabilizing these agents. In this study, we optimized fermentation conditions for the production of the bioinsecticide Paecilomyces fumosoroseus. P. fumosoroseus is a fungus that selectively infects and kills numerous serious insect pests such as the silverleaf whitefly. These studies showed that if this fungus is given a diet containing appropriate sources and concentrations of nitrogen, very high yields of this fungus were rapidly produced in commercially-available, deep-tank fermentors. The fungus produced under these conditions was shown to be stable and effective in killing the silverleaf whitefly. These studies have demonstrated that this environmentally friendly biopesticide can be economically produced using commercially available fermentation equipment. The development of this biologically-based, insect control technology will augment currently used chemical control agents and provide a nonchemical method for controlling various soft-bodied insects in environmentally sensitive areas.
Technical Abstract: In shake flask and fermentor studies, various media components and culture inocula were tested to improve P. fumosoroseus spore production rates, yield and stability. To evaluate inoculum potential and inoculum scale-up for fermentor studies, conidia and liquid culture-produced spores of various strains of P. fumosoroseus were compared as inoculum. Inoculation of liquid cultures with liquid culture-produced blastospores at spore concentrations at least 1 x 10(6) spores/mL resulted in the rapid production of high concentrations of blastospores [ca. 1 x 10(9) spores/mL after 48 hours fermentation time] for all strains tested. The rapid germination rate of blastospores (90% after 6 hours incubation) compared to conidia (>90% after 16 hours incubation) and the use of higher inoculum rates reduced the fermentation time from 96 hours to 48 hours for maximal spore yields. A comparison of various complex nitrogen sources showed that liquid media supplemented with acid hydrolyzed casein or yeast extract supported the production of high concentrations of blastospores that were significantly more desiccation-tolerant (79-82% survival after drying) when compared to blastospores produced in media supplemented with other nitrogen sources (50- 12% survival after drying). These studies have demonstrated that the infective spores of various strains of the fungal bioinsecticide Paecilomyces fumosoroseus can be rapidly produced using deep-tank, liquid culture fermentation techniques.