Isolation from a methanogenic ferulate degrading consortium of an anaerobe that converts methoxyl groups of aromatic acids to volatile fatty acids

Abstract

An anaerobic, non-motile, rod shaped bacterium is described which cleaves the phenylether bonds of methoxylated aromatic substrates to give the corresponding hydroxy aromatic derivatives and mixed volatile fatty acids, chain length, C1, C2 and C4. The bacterium was isolated from an anaerobic digestor fed with contents from a wood fiber to alcohol fermentation plant, using anaerobic rolltube medium with ferulate as the carbon and energy source. Moles fatty acid produced per 100 mole of methoxyl group of aromatic substrate fermented were approximately: acetate, 14; butyrate, 18; and formate, 15. For the fermentation of equimolar amounts of methoxylated aromatic compounds, growth yields were proportional to the number of methoxylated groups per molecule, and the amount of cells per methoxyl group did not alter when phenylacrylate derivatives were used as substrates. The organism was unable to reduce the side-chain double bond of phenylacrylate derivatives. Coculture of the bacterium on ferulate with Methanospirillum hungatei, or Desulfovibrio in the presence of SO 4 = resulted in no nett production of formate, and small quantities of methane and sulfide were produced respectively. The isolate utilized glucose, fructose, and lactate, but not methanol or H2−CO2 as growth substrates. Lactate, butyrate, acetate, formate and small quantities of H2 were produced from glucose fermentation. No reduction of SO 4 = or NO 3 - occurred during fermentation of glucose or methoxylated aromatics and no growth occurred in the presence of oxygen.