Relationship between growth and metabolic activity in the strict chemolithotroph, Thiobacillus thiooxidans

Abstract

The metabolic activity of Thiobacillus thiooxidans was found to decrease rapidly as stationary phase was approached. Keeping the culture at constant pH (4.0) and supplementation with CO2 did not effect the decrease in metabolic activity although growth was increased. The respiration rate of cells obtained from stationary phase was negligible. No growth was obtained when the pH was adjusted to pH 6.0. Measurement of pyruvic acid, an inhibitor of metabolic activity, showed that it reached only about 1.0 × 10−5 M during the early stages of growth and then decreased during exponential growth.