ACID-BASE PROPERTIES OF A SOIL FUNGUS, TRICHODERMA-HARZIANUM

The acid-base properties of mycelium from Trichoderma harzianum were studied as a function of mass, state of mycelia, i.e., starved or nonstarved, and ionic strength of the aqueous phase. The nonstarved mycelia exhibited an extensive buffering behavior, which was attributed to the production of chemical species participating in the resultant equilibrium. Production of such ''acidic'' moieties resulted in higher acid capacities for the nonstarved mycelia (500-800 mequiv/kg mycelia) while for the starved mycelium, negative acid capacities were obtained (approximately -120 mequiv/kg mycelia) indicating a basic surface. Plots of charge balance versus pH showed an insensitivity to ionic strength changes and facilitated the estimation of the point of zero charge (pzc) for the starved mycelia. Similar plots for the nonstarved mycelia showed that this system was sensitive to ionic strength changes and yielded no distinguishable pzc values. It was assumed that the non-starved mycelium possibly allowed transport of ions into its cell wall structure or even intracellularly whereas the starved mycelium did not.