Utilization of various chemotrophic and phototrophic bacteria as food by the anaerobic ciliate Trimyema compressum

Abstract

A monoxenic culture of the anaerobic ciliate Trimyema compressum growing on Bacteroides strain WoCb 15 was tested for growth on 15 chemotrophic and 27 phototrophic bacterial strains as sole food bacteria. Apart from Bacteroides strain WoCb 15, which yielded the highest cell numbers of Trimyema, only 4 species of Gram-negative chemotrophic bacteria and 7 species (13 strains) of phototrophic bacteria (all Gram-negative) supported multiplication of Trimyema. No growth could be obtained on 7 different strains of Gram-positive bacteria. The dry cell mass yield of Trimyema amounted to 6.1% of the dry cell mass of Bacteroides strain WoCb 15 consumed. As a result, only 0.34% of the carbon in the organic substrate (tartrate) consumed for growth and fermentation of Bacteroides strain WoCb 15 ended up in the carbon content of Trimyema. The low yields are due to the fermentative metabolism of both organisms. Trimyema ceased to multiply after consumption of Bacteroides cells down to a number of 1 · 10(7) cells/ml.