Inhibitory effects of saturated fatty acids on methane production by methanogenic <i>Archaea</i>

Abstract

The present study investigated the inhibitory effects of saturated fatty acids on methanogenesis in Archaea, and whether or not competitive inactivation of the methanogens' coenzyme M (HS-CoM) is involved in the inhibition. Strains tested in batch cultures were Methanosarcina barkeri, Methanosarcina mazei, Methanococcus voltae, all incubated at 37C, and Methanothermobacter thermoautotrophicus, incubated at 65C. The fatty acids C 10 , C 12 , C 14 and C 18 were supplemented at 1 mg . ml -1 in cultivation medium. The methanogens were susceptible to C 10 and C 12 , and less so to C 14 . Only M. thermoautotrophicus was affected by C 18 . In M. mazei cultures, excessive HS-CoM did not prevent the action of C 14 which might suggest that competitive inhibition of HS-CoM is not the reason for the SFA-induced effect on methanogenesis. The results indicate that, as a prerequisite to inhibit methanogenesis in Archaea, medium-and long-chain saturated fatty acids have to be at least partially molten.