Fermentative toluene degradation in anaerobic defined syntrophic cocultures

A syntrophic coculture of a new sulfate-reducing isolate, strain TRM1, with Wolinella succinogenes degraded toluene with either fumarate or NO3- as th e terminal electron acceptor. Neither strain TRM1 nor W. succinogenes could metabolise toluene under these conditions in pure culture. Syntrophic degr adation was 2-3 times slower than toluene utilisation by strain TRM1 in pur e culture with sulfate as electron acceptor. The culture did not produce be nzoate or fatty acids like acetate or propionate in detectable amounts. An increase in biomass of the syntrophic toluene-degrading culture was shown i n a growth curve with nitrate as the terminal electron acceptor. Both partn er organisms were detected microscopically at the end of the growth experim ent. Syntrophic degradation of toluene with W. succinogenes and fumarate as the terminal electron acceptor was also demonstrated with the iron reducer Geobacter metallireducens. The results provide the first example of a ferm entative oxidation of an aromatic hydrocarbon in a defined coculture. (C) 1 999 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.