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Pentose metabolism in Rhizobium leguminosarum MNF300 and in cowpea Rhizobium NGR234
Journal article   Peer reviewed

Pentose metabolism in Rhizobium leguminosarum MNF300 and in cowpea Rhizobium NGR234

M.J. Dilworth, R. Arwas, I.A. McKay, S. Saroso and A.R. Glenn
Microbiology, Vol.132(10), pp.2733-2742
1986
DOI: https://doi.org/10.1099/00221287-132-10-2733
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Abstract

L-Arabinose is broken down by Rhizobium leguminosarum MNF300 via 2-oxoglutarate semialdehyde. Enzyme activities in cells grown on succinate, mannitol or arabinose indicated much greater modulation of arabinonate dehydratase, 2-keto-3-deoxyarabinonate dehydratase and 2-oxoglutarate semialdehyde dehydrogenase than of arabinose dehydrogenase or of arabinono-γ-lactonase. In cowpea Rhizobium NGR234, all the enzymes of L-arabinose metabolism except L-arabinono-γ-lactonase were inducible. Assays for such enzymes in snake bean bacteroids indicated that L-arabinose did not reach the bacteroids in large quantities. The Tn5-induced mutant MNF3045 of R. leguminosarum was unable to grow on L-arabinose and accumulated L-arabinono-γ-lactone and L-arabinonate. Product accumulation and enzyme assays suggested that this mutant was defective in L-arabinonate dehydratase. It nodulated peas and the nodules fixed N2, indicating that the supply of L-arabinose is not essential for bacteroid function. Another Tn5-induced mutant of R. leguminosarum, MNF3041, lacked ribokinase and was unable to grow on D-ribose; this mutant was also able to nodulate peas and fix N2.

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