Abstract
The balance of carbon and the efficiency of growth yield were studied using E. coli as a typical bacterium and glucose as the sole organic substance. The efficiency of growth yield to the decrease of substrate, the evolution of CO_2 and the excretion of waste products were, respectively, 0.54,0.36 and 0.11 in terms of carbon, and these values were almost constant throughout the whole growing stage. Furthermore, the amount of glucose incorporated, CO_2 evolved and the waste products excreted by one cell during its one generation time seemed to be constant throughout the whole growing stage, i.e., the unit of biomass(1.00)incorporated 1.73 glucose, evolved 0.68 CO_2 and excreted 0.19 waste products for one generation time. The growth curves of E. coli and mixed bacterial population decomposing glucose under the influence of aeration with CO_2-containing or CO_2-free air and of repeated preculture were the same in type and yield efficiencies were also the same(0.54), irrespective of the length of lag time. Different substrate gave different growth yield, but the growth yield seemed to be independent of temperature for a wide range. As a biogeochemical agent, the role of bacterial population in the turn-over of material and in the mineralization of organic compound was also discussed.
