STIMULATION OF BACTERIAL PROTEOLYSIS BY ADSORBENTS

Abstract

Summary A comparison of the initial rate of NH, production from protein adsorbed on kaolinite and non‐adsorbed protein by bacteria showed that adsorption enhanced the rate. This effect occurs with both adsorbed and non‐adsorbed organisms, and disappears when a non‐adsorbed substrate (denatured lysozyme predigested by chymotrypsin) is used. With Flavobacterium sp. the effect occurred with a dilute inoculum and disappeared with a concentrated one. Shaking cultures of Flavobacterium sp., which ordinarily is c. 98 per cent. adsorbed to kaolinite, and of Pseudomonas sp., which is only c. 30 per cent. adsorbed to kaolinite statically, which might dislodge organisms from the clay, did not decrease rates of NHs liberation. It is concluded that the kaolinite acts as a concentrating surface for adsorbed substrate and exoenzymes, and thereby brings about a more rapid break‐down of substrate. Flavobacterium sp. readily attacks protein adsorbed on bentonite with a resulting decrease in (001) X‐ray diffraction spacing.