Evidence for the production of chemical compounds analogous to nod factor by the silicate bacterium Bacillus circulans GY92

Abstract

Silicate bacteria are generally placed in the species Bacillus circulans and are widely used in biological fertilisers and biological leaching. The bacteria can form conspicuous amounts of extracellular polysaccharides in nitrogen-free media or in the presence of substrates with large C/N ratios. Using high performance liquid chromatography, we have shown that B. circulans produced a new peak/compound when induced with the plant-to-bacteria signal molecule genistein. This material co-eluted with the lipo-chitooligosaccharide (Nod Bj-V (C 18:1, MeFuc)) of Bradyrhizobium japonicum. This compound exhibited root hair deformation activity on soybean, which is characteristic of lipo-chitooligosaccharides (LCOs). We propose that this might be an LCO or closely related compound with similar biological activity.