The yields of Streptococcus faecalis grown in continuous culture

Publisher Website
Google Scholar
Abstract
SUMMARY: Streptococcus faecalis has been grown anaerobically in continuous culture on a denned medium. Under these conditions it is possible to maintain (a) the glucose concentration, (b) the tryptophan concentration, and (c) the generation time at predetermined values, and to study the effects of changes in these variables on the culture. When growth was limited by the glucose supply, the glucose yield constant (dry weight of cells formed/weight of glucose used) was greater than when tryptophan was limiting. The glucose yield constant under conditions of tryptophan limitation progressively fell with increasing supplies of glucose until it reached a minimum value. Under conditions of tryptophan limitation and large excess of glucose, the amount of glucose used per unit weight of cells per unit time remained roughly constant irrespective of growth rate. It is concluded that the needs of cell synthesis in S. faecalis do not control the rate of glucose breakdown, i.e. the rate of the energy-yielding metabolism. At slow growth rates the end products of glucose metabolism included volatile fatty acids, which were not present, or present in small amounts, at faster growth rates.