Carbon isotope fractionation in bacterial production of methane.

Anaerobic bacteria from a Pacific Ocean mud cause unusually large carbon isotope fractionations during fermentation of methanol. The methane produced is about 8 percent enriched in C(12), relative to the original methanol. Fractionation factors determined at 30 degrees C and 23 degrees C were 1.081 and 1.094, respectively, which indicates that this process is dependent on temperature.