INFLUENCE OF CLAY MINERALS ON MICROORGANISMS: III. EFFECT OF PARTICLE SIZE, CATION EXCHANGE CAPACITY, AND SURFACE AREA ON BACTERIA

The stimulation of bacterial respiration by clay minerals was related to certain physicochemical characteristics of clays. Respiration increased with an increase in the cation exchange capacity and surface area of the particles. The importance of surface area, however, could not be unequivocally established, as some of the methods used to determine this characteristic on certain clay species were questionable. Particle size did not appear to be a critical characteristic. The implications of the cation exchange capacity of clay minerals in the activity, ecology, and population dynamics of microorganisms in nature are discussed.