Bidirectional transformation of aromatic aldehydes by Desulfovibrio desulfuricans under nitrate-dissimilating conditions

Reduction of 3-chlorobenzoate, 3-bromobenzoate, and benzoate to corresponding alcohols by Desulfomicrobium escambiense, isolated from a 3-chlorobenzoate-dechlorinating coculture

An anaerobic bacterial coculture which dechlorinated 3-chlorobenzoate (3CB) to benzoate was obtained by single-colony isolation from an anaerobic bacterial consortium which completely degraded 3CB in defined medium. Of 29 additional halogenated aromatic compounds tested, the coculture removed the meta halogen from 2,3- and 2,5-dichlorobenzoate, 3-bromobenzoate (3BB), 5-chlorovanillate (5CV), and 3-chloro-4-hydroxybenzoate. Dechlorinating activity in the coculture required the presence of pyruvate. 5CV was also O-demethoxylated. The coculture contained two cell types: a short, straight gram-negative rod and a long, thin, curved gram-positive rod. The short rod, Desulfomicrobium escambiense, was recently isolated and identified as a new sulfate-reducing bacterial species (B. R. Sharak Genthner, S. D. Friedman, and R. Devereux, Int. J. Syst. Bacteriol. 47:889-892, 1997; B. R. Sharak Genthner, G. Mundfrom, and R. Devereux, Arch. Microbiol. 161:215-219, 1994). D. escambiense did not dehalogenate any of the compounds dehalogenated by the coculture, nor dit it O-demethoxylate 5CV or vanillate. However, D. escambiense reduced 3CB, EBB, and benzoate to their respective benzyl alcohols. Reduction to alcohols required the presence of pyruvate, which was transformed to acetate, lactate, and succinate in the presence of absence of 3CB, 3BB, or benzoate. Alcohol formation did not occur in pyruvate-sulfate medium. Under these conditions, sulfate was preferentially reduced. Other electron donors that supported the growth of D. escambiense during sulfate reduction did not support benzoate reduction to benzyl alcohol.

Anaerobic Transformation of Furfural by Methanococcus deltae (Delta)LH

Methanococcus deltae (Delta)LH was grown on H(inf2)-CO(inf2) in the presence of various concentrations of furfural. Furfural at higher concentrations, namely, 20 and 25 mM, inhibited growth of this organism. At concentration of 5 and 10 mM, no inhibition of growth was observed. The other methanogens in this study were not inhibited by 10 mM furfural. Among the methanogens tested, M. deltae was capable of transforming furfural, whereas Methanobacterium thermoautotrophicum Marburg, Methanosarcina barkeri 227, Methanococcus thermolithotrophicus, and Methanobrevibacter ruminantium lacked this capability. One hundred percent removal of furfural was observed within 48 h of incubation in M. deltae cultures. The end product observed during furfural metabolism was furfuryl alcohol. An almost stoichiometric amount of furfuryl alcohol was produced by M. deltae. This transformation is likely to be of value in the detoxification of furfural and in its ultimate conversion to methane and CO(inf2) by anaerobic digestion.