Radiorespirometric Studies of Leucothrix mucor

Catabolic capabilities ofLeucothrix mucor were studied by radiorespirometric technique with a liquid scintillation spectrometer. Through measurement of relative rates and total percentages of14 CO2 produced, together with the determination of the cellular incorporation of14 C from different carbon atoms of various labeled substrates, such as simple carbohydrates, intermediary metabolites, and amino acids, the essential characteristics of the primary and secondary pathways operative in this organism were examined. These substrates appeared to be degraded mainly via enzymes of the Entner-Doudoroff pathway in conjunction with the tricarboxylic acid cycle. Estimation of concurrent participation of pathways indicated that 20 to 25% of the administered carbohydrate was catabolized via the pentose phosphate pathway. There was no evidence of the Embden-Meyerhof-Parnas pathway operating in this organism.