The Growth of Micro-organisms in Relation to their Energy Supply

Agricultural Research Council Unit for Microbiology, Department of Microbiology, The University of Sheffield, Sheffield 10 ABSTRACT SUMMARY: When Streptococcus faecalis was grown anaerobically in a complex medium containing D -glucose, D -ribose or L -arginine as energy source the dry wt. of organism produced was proportional to the concentration of the energy source in the medium. However, S. faecalis will not grow in a defined medium with arginine as the energy source unless glucose is present at the same time. The anaerobic growth of both Saccharomyces cerevisiae and Pseudomonas lindneri was proportional to the concentration of glucose in the medium and the yield coefficient—defined as g. dry wt. organism/mole glucose—of the former was the same as that of S. faecalis grown upon glucose and approximately twice that of P. lindneri. Calculation of the g. dry wt. organism/mole adenosine triphosphate synthesized for these three organisms gave values ranging from 12.6 to 8.3 with an average of 10.5. These results suggest that, under anaerobic conditions, the yield of S. faecalis, S. cerevisiae and P. lindneri was proportional to the amount of ATP synthesized. When Propionibacterium pentosaceum was grown anaerobically with glucose, glycerol or DL -lactate as energy source there was, in all three cases, a linear relationship between the dry wt. of organisms produced and the concentration of the energy source in the medium. The values of the yield coefficients obtained were compatible with the formation of approximately 4 mole ATP/mole glucose, 2 mole ATP/mole glycerol and 1 mole ATP/mole lactate. * Present address: The Wellcome Laboratories of Tropical Medicine, Euston Rd, London, N.W. 1.