DEGRADATION OF FOOD COMPOUNDS AND GROWTH-RESPONSE ON DIFFERENT FOOD QUALITY BY THE ANAEROBIC CILIATE TRIMYEMA-COMPRESSUM

The biochemical composition of two food bacteria was examined on which monoxenic cultures of Trimyema compressum grew with different yields. The food bacteria were the saccharolytic fermenting bacterium Bactero ides WoCb15 and the purple nonsulfur bacterium Rubrivivax gelatinosus. Differences in composition of bacterial biomass concerned mainly the carbohydrate content. By different culture conditions for R. gelatinos us and pasteurization of carbohydrate-rich cells, we were able to feed the ciliate with food mixtures of different carbohydrate content. Dry mass yields of the ciliate reached a maximum with mixtures of 80% car bohydrate-rich pasteurized cells plus 20% carbohydrate-poor living cel ls. In the absence of degradable carbohydrate, energy metabolism depen ded on protein as substrate. Utilization of protein was incomplete, la rge amounts were converted into soluble compounds that accumulated in the culture medium. The ciliate consumed storage carbohydrate of livin g or pasteurized food bacteria equally well, while growth with short g eneration times was still dependent on a certain percentage of living bacteria as source of native protein. Lipids, nucleic acids and denatu red proteins were not degradable by the ciliate. Consequences for the fermentative metabolism of Trimyema compressum are discussed.