CITRIC ACID METABOLISM OF AEROBACTER AEROGENES

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Abstract
The rate of keto-acid accumulation in citrate-phosphate buffer under aeration by citrate-grown cells was detd. Cells grown anaerobically produce pyruvate only and its production is independent of anaerobiosis. Cells grown aerobically produce mainly alpha-ketoglutarate and small amts. of pyruvate. Anaerobiosis reduces keto-acid production by these cells. Anaerobic citrate dissimilation apparently is dependent on an adaptive enzyme system whose development is suppressed by growth in aerobic conditions. Diauxie growth is exhibited by cells growing in unaerated glucose-citrate media, and during growth on glucose, enzymes responsible for citrate fermentation are suppressed. Growth in unaerated media containing concns. greater than 5.4 x 10-2 [image] citrate cases with citrate unconsumed, and the ability of the cells to produce pyruvate rapidly from citrate is impaired. These phenomena are attributed to the action of accumulated acetic acid. In the presence of 0.0025 [image] AS2O3 pyruvate accumulates during citrate dissimilation and an approx. equimolar amt. of CO2 is evolved. The formic hydrogenylase activity of cells grown on citrate was studied also.