EFFECT OF FLUOROACETATES ON METHANOGENESIS IN SAMPLES FROM SELECTED METHANOGENIC ENVIRONMENTS

Trifluoroacetic acid (IFA) is an atmospheric decomposition product of a new generation of refrigerants that will replace current ozone-deple ting CFCs. The effect of trifluoroacetic acid on microbial methanogene sis was assessed using environmental samples from four distinct methan ogenic systems: the anaerobic digestor, the rumen, freshwater sediment s, and marine sediments. TFA exhibited no toxcity, as evidenced by the rare of methanogenesis, at concentrations up to 10 mM. [1-C-14]TFA wa s used to test for biodegradation (release of (CO2)-C-14) in methanoge nic marine sediments. No significant release of (CO2)-C-14 was observe d. As a control, the toxic monofluoroacetate (MFA), which is not an at mospheric degradation product of CFC replacements, was found to inhibi t methanogenesis in freshwater and anaerobic digestor samples al or ab ove concentrations of 0.1 mM. We conclude that TFA is inert in these m ethanogenic systems and there is no evident toxicity to either the met hanogenic or fermentative populations.