Metabolic Activity of Fatty Acid-Oxidizing Bacteria and the Contribution of Acetate, Propionate, Butyrate, and CO2 to Methanogenesis in Cattle Waste at 40 and 60°C

摘要: The quantitative contribution of fatty acids and CO2 to methanogenesis was studied by using stirred, 3-liter bench-top digestors fed on a semicontinuous basis with cattle waste. fermentations were carried out at 40 60°C under identical loading conditions (6 g volatile solids per liter reactor volume day, 10-day retention time). In the thermophilic digestor, acetate turnover increased from prefeeding level 16 μM/min peak (49 μM/min) 1 h after feeding then gradually decreased. Acetate in mesophilic digestor 15 μM/min. Propionate ranged 2 5.2 1.5 4.5 digestors, respectively. Butyrate (0.7 1.2 similar both digestors. proportion CH4 produced via methyl group varied time 72 75% 75 86% digestor. reduction 24 29% 19 27%, butyrate accounted for 20% total produced. synthesis greatest shortly higher (0.5 2.4 than (0.3 0.5 μM/min). Counts acid-degrading bacteria related their activity.