Metabolism of Some Polyols by Rhizobium meliloti

Abstract

The utilization of d -mannitol, d -arabitol, and d -sorbitol by Rhizobium meliloti was studied in extracts from mannitol-grown cells. Two different polyol dehydrogenases were induced by any of these polyols: (i) a nicotinamide adenine dinucleotide (NAD)-arabitol dehydrogenase and (ii) a NAD-sorbitol dehydrogenase, whereas polyol phosphate dehydrogenases were absent. d -Arabitol dehydrogenase was observed to act on both d -arabitol and d -mannitol, but d -sorbitol dehydrogenase acted specifically on d -sorbitol. d -Arabitol was oxidized to d -xylulose, d -mannitol and d -sorbitol were oxidized to d -fructose. An adenosine triphosphate-linked hexokinase which acts on d -fructose and absence of hexose isomerase were also detected in this organism.