ANAEROBIC TAURINE OXIDATION - A NOVEL REACTION BY A NITRATE-REDUCING ALCALIGENES SP

Enrichment cultures were prepared under strictly anoxic conditions in medium representing fresh water and containing an organosulfonate as e lectron donor and carbon source, and nitrate as electron acceptor. The inoculum was from the anaerobic digestor of two communal sewage works . The natural organosulfonates 2-aminoethanesulfonate (taurine), DL-2- amino-3-sulfopropionate (cysteate) and 2-hydroxyethanesulfonate (iseth ionate) all gave positive enrichments, whereas unsubstituted alkanesul fonates, such as methanesulfonate and arenesulfonates, gave no enrichm ent. Two representative enrichments were used to obtain pure cultures, and strains NKNTAU (utilizing taurine) and NKNIS (utilizing isethiona te) were isolated. Strain NKNTAU was examined in detail. Out of 18 tes ted organosulfonates, it utilized only one, taurine, and was identifie d as a novel Alcaligenes sp., a facultatively anaerobic bacterium. Car bon from taurine was converted to cell material and carbon dioxide. Th e amino group was released as ammonium ion and the sulfonate moiety wa s recovered as sulfate. Nitrate was reduced to nitrogen gas.