INFLUENCE OF CLAY MINERALS ON MICROORGANISMS: IV. MONTMORILLONITE AND KAOLINITE ON FUNGI

Abstract

The respiration of mycelial homogenates of 27 fungal species representing 4 classes was generally not affected by pH nor by montmorillonite or kaolinite at concentrations below 4%. Respiration was markedly inhibited by montmorillonite at concentrations of 4% and above, but comparable inhibition by kaolinite occurred only at concentrations above 40%. The inhibition was greater as the metabolic activity of the mycelium increased but was not caused by a limitation in C substrate. The inhibition was related to the viscosity of the systems, which, in turn, presumably influenced the rate of O2 diffusion. The viscosities of systems containing montmorillonite were vastly greater than those containing kaolinite. These results were in contrast to those previously obtained with bacteria, which revealed that montmorillonite greatly stimulated respiration.