Characteristics of methane and bioflocculant production by Methanosarcina spelaei RK-23. (14th April 2020) - Zhao, Haijuan
Abstract: This study aimed to isolate a novel archaeon capable of simultaneously producing methane and bioflocculants. The isolated methanogen was identified as Methanosarcina spelaei RK-23 by molecular characterization. Strain RK-23 grew with different carbon sources, but acetate was found to be the most beneficial carbon source for the production of methane and bioflocculants. Moreover, RK-23 produced methane and bioflocculants within an initial pH range of 5.0–8.0, with an optimal pH for methane production of 6.5 and flocculating activity of 7.0. In addition, strain RK-23 exhibited tolerance to high-salinity conditions and produced methane and bioflocculants within 0–1.2 M NaCl, with an optimum NaCl concentration of 0.3 M. The methane production and flocculating activity of strain RK-23 under optimal culture conditions were 17.4 mmol methane/mol acetate and 95.6%, respectively. MBF-23 mostly consisted of 83.5% carbohydrates and 14.3% proteins. Furthermore, the bridging of adsorption is believed to be the main bioflocculation mechanism in this study. Highlights: A novel bioflocculant-producing methanogen, Methanosarcina spelaei RK-23, was isolated. RK-23 converted acetate to methane and MBF-23. RK-23 secreted methane and MBF-23 within a wide salinity range. MBF-23 was negatively charged, with a molecular weight of 3.5 × 10 6 Da.