Chemotaxis of a Ralstonia sp SJ98 toward different nitroaromatic compoundsand their degradation

A Ralstonia sp. SJ98, isolated by a chemotactic enrichment technique, was c apable of utilizing different nitroaromatic compounds (NACs). It utilized p -nitrophenol, 4-nitrocatechol, o-nitrobenzoic acid, and p-nitrobenzoic acid as the sole source of carbon and energy. It was observed that Ralstonia sp . SJ98 was chemotactic to the above-mentioned NACs as tested by the drop as say, swarm plate assay, and capillary assay. However, it failed to show che motactic behavior toward those compounds which were not degraded by the mic roorganism. This is the first report which shows the chemotaxis of a microo rganism toward different NACs and their subsequent degradation. Some of the intermediates of the NACs' degradative pathways have been identified using TLC, GC, and GC-MS studies. The results presented here indicate a correlat ion between chemotaxis and biodegradation of NACs. (C) 2000 Academic Press.