Biotechnology Letters Vol 8 No 1 25-30 (1986) THE EVALUATION OF MECHANICAL CHOPPING FUNGAL MYCELIA AS A METHOD OF INCREASING FUNGAL BIOMASS. G. Murase and B. Kendrick Department of Biology University of Waterloo WATERLOO, Ontario, Canada N2L 3G1 SUMMARY The finding that any comminution of fungal hyphae in broth culture markedly decreases yield negates the possibility of applying brief periods of chopping in an industrial setting to increase biomass. INTRODUCTION One aim in fungal biotechnology is to maximize fungal biomass and minimize growing time. Most fungal hyphae normally grow only at the tip, but it has been established that fragments of fungal hyphae are usually totipotent; that is, they are capable of regenerating the entire organism, if they are more than 1 em long, and if each contains a nucleus and some cytoplasm (Robinson 1978). Solomons (1975) demonstrated that mycelial fragments can regenerate a hyphal tip at each end. We therefore hypothesized that if we could mechanicallyincrease the number of viable hyphal tips by chopping up the mycelium, growth would be enhanced. The purpose of this experiment was to examine the potential of this proposal, using chopping as the means of comminution, by varying the duration of the chopping and monitoring dry weights of treated versus control samples over time. MATERIALS AND METHODS Chaetomium cellulolyticum Chahal & Hawksworth, was grown in Potato Dextrose Broth (PDB) (200 g potatoes, 20 g dextrose, 0.1 g chloramphenicol, 1000 mL distilled water) at 37~ on a Gyrotary Shaker, Model G-2 (New Brunswick Scientific Co. Inc.) at 150 rpm with a total throw of 2.5 cm. In all instances a 10% (v/v) inoculum was used. For each chopping treatment the cultures were pooled, chopped and then maintained in a sterile screw-cap flask kept on a magnetic stir-bar system to ensure that homogeneous aliquots were dispensed. 25