Manganese elicits the synthesis of a novel exopolysaccharide in an arctic Rhizobium

Under the influence of manganese (400μM), the arctic Rhizobium N11 [(1986) Arch. Microbiol. 146, 12–18] appeared to elaborate an exopolysaccharide that showed marked diversity with that synthesized in a medium deficient in added manganese. Both total carbohydrate and the uronic acid contents of these biomolecules appear to differ substantially. 13C-NMR spectroscopy revealed three distinct signals in the anomeric region of the spectrum derived from the biopolymer secreted in the manganese rich medium, while that from the other exopolysaccharide exhibited numerous peaks. The resonance lines indicative of the non-carbohydrate moieties were also found to be dissimilar. Further evidence for the unidentical nature of these biopolymers was obtained from viscosity and optical rotation measurements.