Conidiation of Trichoderma atroviride isolate during submerged cultivation in a laboratory stirred-tank fermenter

Conditions for conidiation of a natural isolate of Trichoderma atroviride during submerged cultivation in Erlenmeyer flasks and in a laboratory stirred-tank fermenter were optimized. From the simple sugars tested, cellobiose was the best substrate for conidia production while cellulose fines from paper mill waste proved to be a suitable cheap complex carbon source. Optimum temperature for conidiation was 24-26 degrees C, and the required dissolved oxygen level was > 40% saturation. After initial slight decrease during the 1st d after inoculation, the pH of the culture medium constantly increased throughout the sporulation period. Attempts to regulate the pH during fermentation did not improve the spore yields. The most intense formation of conidia took place between 2nd and 3rd d of growth and the overall volumetric productivity of conidia was 4.1-8.2 x 10(9) conidia per L/h.