Submitted to: World Journal of Microbiology and Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/5/2001
Publication Date: 7/26/2001
Citation: SANDOVAL-CORONADO, C.F., LUNA-OLVERA, H.A., AREVALO-NINO, K., JACKSON, M.A., POPRAWSKI, T.J., GALAN-WONG, L.J. DRYING AND FORMULATION OF BLASTOSPORES OF PAECILOMYCES FUMOSOROSEUS (HYPHOMYCETES) PRODUCED IN TWO DIFFERENT LIQUID MEDIA. WORLD JOURNAL OF MICROBIOLOGY AND BIOTECHNOLOGY. 2001. v. 17. p. 423-428.
Interpretive Summary: Both the nutritional diet in which cells are grown and the formulation material in which they are dried have been shown to impact on the shelf-life and efficacy of microbial biological control agents. In this study, spores of the bioinsecticidal fungus Paecilomyces fumosoroseus were produced using liquid fermentation in two nutritionally different media and dair-dried using various formulation materials. Spore production in liquid medium supplied nitrogen in the form acid hydrolyzed casein were significantly higher when compared to spore yields in liquid medium containing digests of collagen as the nitrogen source. Initial spore survival after air-drying was affected by the production medium and the formulation materials tested. Diet, formulation material, and storage temperature had an impact on the shelf-life of the bioinsecticide. In all formulations, spore shelf-life was reduced by storage at 28 deg C rather than 4 deg C. These studies demonstrate the importance of diet, formulation material, and storage conditions on the shelf-life of spores of the bioinsecticidal fungus P. fumosoroseus.
Technical Abstract: Formulation matrices can play an important role in improving the storage survival and biocontrol efficacy of microorganisms used for the control of pest insects. In this study, liquid culture-produced blastospores of Paecilomyces fumosoroseus were formulated with different inert and organic materials prior to air-drying. P. fumosoroseus blastospores were produced in two different liquid media, a basal salts medium supplemented with glucose and Casamino acids (LM1) or peptone of collagen (LM2). Blastospores produced in the two media were formulated with various supports: cornstarch, rice flour, talc powders, Mexican lime, calcined kaolin clay, and diatomaceous earth. Several of the supports were tested at different concentrations. The initial and long-term (after storage at 4 and 28 deg C) survival of the formulated, air-dried blastospores were evaluated. Initial blastospore viabilities were affected by the formulation material and by the blastospore production medium. Medium composition, drying support, and storage temperature had an impact on the long-term survival of the blastospores. Under the conditions of the study, LM1 produced higher concentrations of blastospores that not only survived drying better than blastospores produced in LM2 but also maintained viability longer during storage in the formulation supports tested. The nature of the drying supports was shown to have a significant impact on the storage stability of all blastospores, particularly those produced in LM1. Under the production, drying, and storage conditions used in the study, calcined kaolin clay formulations stored at 4 deg C had the best storage stability. In all formulations, spore survival over time was reduced for blastospore formulations stored at 28 deg C rather than 4 deg C.