Anaerobic degradation and methanogenic inhibitory effects of oleic and stearic acids.
Oleic acid, an 18 carbon acid with one double bond (C18:1) was degraded anaerobically to palmitic (C16:0) and myristic (C14:0) acid by-products at 21 C by a culture unacclimated to long-chain fatty acids. These by-products were degraded to acetate and ultimately to methane. In comparison, no long-chain fatty acid by-products were observed in unacclimated anaerobic cultures receiving stearic (C18:0) acid although slow removal of stearic acid occurred. Oleic acid concentrations above 30mg l(-1) inhibited acetate degradation but stearic acid up to 100 mg l(-1) did not inhibit aceticlastic methanogenesis. Hydrogenotrophic methanogenesis was slightly inhibited by oleic and stearic acids. A thermodynamic basis for comparing anaerobic C18 acid degradation and predicting by-products is presented.
Lalman
J A
JA
Department of Biosystems and Agricultural Engineering, Oklahoma State University, Stillwater 74078-6021, USA.
Bagley
D M
DM
D019342:Acetic Acid / Q000378:metabolism*; D000693:Anaerobiosis; D001673:Biodegradation, Environmental; D018533:Biomass; D019149:Bioreactors; D005525:Food-Processing Industry / Q000379:methods; D006859:Hydrogen / Q000378:metabolism; D007220:Industrial Waste / Q000032:analysis; D008697:Methane / Q000378:metabolism*; D019301:Oleic Acid / Q000378:metabolism / Q000494:pharmacology*; D010084:Oxidation-Reduction; D012722:Sewage / Q000737:chemistry / Q000382:microbiology; D013229:Stearic Acids / Q000378:metabolism / Q000494:pharmacology*; D014874:Water Pollutants, Chemical / Q000378:metabolism*
D007220:Industrial Waste; D012722:Sewage; D013229:Stearic Acids; D014874:Water Pollutants, Chemical; D019301:Oleic Acid; C031183:stearic acid; D006859:Hydrogen; D008697:Methane; D019342:Acetic Acid