Conklin Anne, Stensel H David, Ferguson John
Carollo Engineers, Seattle, Washington, USA.
Water Environ Res. 2006 May;78(5):486-96. doi: 10.2175/106143006x95393.
Methanosarcina species with a high maximum specific growth rate (mumax) and high half-saturation coefficient (KS) and Methanosaeta species with a low mumax and low KS are the only known aceticlastic methanogens. Because of Methanosaeta's low KS, the low acetate concentrations in conventional, mesophilic anaerobic digestion yield Methanosaeta dominance. However, Methanosarcina absorbs increases in acetate more efficiently and thus promotes more stable digestion. This paper tests the hypothesis that decreasing digester feeding frequencies can increase Methanosarcina predominance. Two acetate-fed reactors were established at a 17-day solids retention time. One reactor was fed hourly, and one was fed once daily. Microscopic and molecular methods were used to verify that the hourly fed reactor enriched for Methanosaeta, while the daily fed reactor enriched for Methanosarcina. Growth and substrate-use kinetics were measured for each reactor. A digester overload condition was simulated, and the Methanosarcina-enriched reactor was found to perform better than the Methanosaeta-enriched reactor. These findings indicate that Methanosarcina dominance can be achieved with infrequent feedings, leading to more stable digestion.
具有高最大比生长速率（μmₐₓ）和高半饱和系数（Kₛ）的甲烷八叠球菌属以及具有低μmₐₓ和低Kₛ的甲烷丝状菌属是仅知的乙酸营养型产甲烷菌。由于甲烷丝状菌属的Kₛ较低，在传统的中温厌氧消化中，低乙酸盐浓度会导致甲烷丝状菌属占主导。然而，甲烷八叠球菌属能更有效地吸收增加的乙酸盐，从而促进更稳定的消化。本文验证了一个假设，即降低消化器进料频率可增加甲烷八叠球菌属的优势地位。在17天的固体停留时间下建立了两个以乙酸盐为进料的反应器。一个反应器每小时进料一次，另一个反应器每天进料一次。使用显微镜和分子方法验证了每小时进料一次的反应器富集了甲烷丝状菌属，而每天进料一次的反应器富集了甲烷八叠球菌属。测量了每个反应器的生长和底物利用动力学。模拟了消化器过载情况，发现富集甲烷八叠球菌属的反应器比富集甲烷丝状菌属的反应器性能更好。这些发现表明，通过不频繁进料可实现甲烷八叠球菌属的优势地位，从而实现更稳定的消化。
