Jung Heejung, Yu Hyeonjung, Lee Changsoo
Department of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Eonyang-eup, Ulju-gun, Ulsan 44919, Republic of Korea.
Graduate School of Carbon Neutrality, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Eonyang-eup, Ulju-gun, Ulsan 44919, Republic of Korea.
iScience. 2023 Aug 1;26(9):107504. doi: 10.1016/j.isci.2023.107504. eCollection 2023 Sep 15.
Electric syntrophy between fatty acid oxidizers and methanogens through direct interspecies electron transfer (DIET) is essential for balancing acidogenesis and methanogenesis in anaerobic digestion. Promoting DIET using electrically conductive additives proved effective in enhancing methanogenesis; however, its possibility to affect other microbial redox reactions in methanogenic systems has been little studied. This study provides the first confirmation of the electro-syntrophic coupling of sulfide oxidation to S with CO-reducing methanogenesis in sulfur-rich methanogenic cultures supplemented with conductive magnetite (100-700-nm particle size). The HS content in biogas, initially exceeding 5000 ppmv, decreased to below 1 ppmv along with an accumulation of extracellular S (60-70 mg/L; initially <1 mg/L) at a magnetite dose of 20 mM Fe, while there were no significant changes in methane yield. A comprehensive polyphasic approach demonstrated that the S formation occurs through electro-syntrophic oxidation of sulfide coupled with CO-reducing methanogenesis, involving as the dominant methanogen.
通过直接种间电子传递（DIET）实现的脂肪酸氧化菌与产甲烷菌之间的电互营作用对于厌氧消化中酸生成和甲烷生成的平衡至关重要。使用导电添加剂促进DIET被证明对增强甲烷生成有效；然而，其影响产甲烷系统中其他微生物氧化还原反应的可能性鲜有研究。本研究首次证实了在添加了导电磁铁矿（粒径为100 - 700纳米）的富硫产甲烷培养物中，硫化物氧化与以CO为底物的甲烷生成之间存在电互营耦合作用。在磁铁矿剂量为20 mM Fe时，沼气中HS含量最初超过5000 ppmv，随着细胞外硫的积累（60 - 70 mg/L；最初<1 mg/L）降至1 ppmv以下，而甲烷产量没有显著变化。一种综合的多相方法表明，硫的形成是通过硫化物的电互营氧化与以CO为底物的甲烷生成耦合发生的，其中 作为主要的产甲烷菌。
