Metabolism of Glucose in Extremely Halophilic Bacteria

Abstract

Though extremely halophilic bacteria have been thought not to utilize carbohydrates, an extreme halophile strain R 113, isolated from a rock salt, was proved to utilize glucose, galactose and maltose. The pathway of glucose degradation by R 113 was investigated. The following reactions were found to be carried out by cell free extract of R 113 grown on glucose; NADP-linked dehydrogenation of glucose to gluconate, dehydration of gluconate to 2-keto-3-deoxyglu-conate, and phosphorylation of the keto acid followed by cleavage to yield pyruvate and glyceral-dehyde-3-phosphate. In this organism, therefore, glucose was degraded via a modified Entner-Doudoroff pathway. Every enzyme involved in the pathway was characterized with respect to the requirements for NaC1 and Mg ion.