Production of a high molecular weight levan by Bacillus paralicheniformis, an industrially and agriculturally important isolate from the buffalo grass rhizosphere.

Abstract

A new exopolysaccharide (EPS) producing Gram-positive bacterium was isolated from the rhizosphere of Bouteloua dactyloides (buffalo grass) and its EPS product was structurally characterized. The isolate, designated as LB1-1A, was identified as Bacillus paralicheniformis based on 16S rRNA gene sequence and phylogenetic tree analysis. The EPS produced by LB1-1A was identified as a levan, having β(2 → 6) linked backbone with β(2 → 1) linkages at the branch points (4.66%). The isolate LB1-1A yielded large amount (~ 42g/l) of levan having high weight average molecular weight (Mw) of 5.517 × 107Da. The relatively low degree of branching and high molecular weight of this levan makes B. paralicheniformis LB1-1A a promising candidate for industrial applications.