PHYSIOLOGY OF PRODUCTION OF VIABLE BIOMASS AND SPORE INOCULUM FOR THEBIOCONTROL AGENT IDRIELLA (MICRODOCHIUM) BOLLEYI

Biomass of the biocontrol agent Idriella bolleyi can be produced in su bmerged liquid culture as mycelium, conidia, and chlamydospores. Each fraction was separated and quantified. The conidial fraction appeared to be the most thermotolerant, suggesting that this form had the best potential shelf life of the three. Conidia were produced during the ea rly phase of growth and their production did not appear to require any form of nutrient exhaustion or growth rate decay. The highest viabili ty per unit biomass was obtained in carbon-limited medium, with sodium nitrate as the nitrogen source, after 6 h. Maximum biomass was not ob tained in this medium until 167 h and, as the biocontrol product is li kely to be sold by weight, an acceptable compromise between the two pa rameters must be found. Excess ammonium chloride in the medium appeare d to inhibit growth. A procedure, involving culture homogenization, wa s adopted in order to estimate potential viability in shake-flask liqu id culture.