Studies were conducted using radiolabeled sodium bicarbonate. Experiments determining the fate of the radiolabeled isotopes were conducted in septum sealed 60 ml volatile organic analysis vial. These vials contained 10ml of cell suspension and 2 small test tubes to which 2 ml of KOH was added to one of the tubes at the end of the experiment to trap any remaining CO2. Following the removal of the KOH from the first tube, 2 ml of n-hexadecane was added to the other test tube to trap any radiolabeled CH4 that was produced by the microorganisms. Unfortunately, none of the 22 cultures screened showed any radioactivity in the hexadecane phase indicating that the radiolabeled sodium bicarbonate was not incorporated into methane. However four of the cultures did show radiation in the lipid and protein extracts suggesting that CO2 had been taken up and incorporated into cellular material.