Murali Nanditha, Srinivas Keerthi, Ahring Birgitte K
Department of Chemical Engineering, Voiland College of Engineering and Architecture, Washington State University, Pullman, WA 99163, USA.
Bio-Products, Sciences and Engineering Laboratory, Washington State University, Richland, WA 99354, USA.
Microorganisms. 2021 Feb 8;9(2):337. doi: 10.3390/microorganisms9020337.
Volatile fatty acids (VFA) are industrially versatile chemicals and have a major market. Although currently produced from petrochemicals, chemical industries are moving towards more bio-based VFA produced from abundant, cheap and renewable sources such as lignocellulosic biomass. In this study, we examined the effect of bioaugmentation with homoacetogenic bacteria for increasing VFA production in lignocellulose fermentation process. The central hypothesis of this study was that inhibition of methanogenesis in an in vitro rumen bioreactor fed with lignocellulosic biomass hydrolysate increases the hydrogen partial pressure, which can be redirected towards increased VFA production, particularly acetic acid, through targeted bioaugmentation with known homoacetogenic bacteria. In this study, methanogenesis during ruminal fermentation of wet exploded corn stover was initially inhibited with 10 mM of 2-bromoethanesulfonate (BES), followed by bioaugmentation with either and in two separate bioreactors. During the inhibition phase, we found that addition of BES decreased the acetic acid yield by 24%, while increasing headspace hydrogen from 1% to 60%. After bioaugmentation, the headspace hydrogen was consumed in both bioreactors and the concentration of acetic acids increased 45% when was added and 70% with added. This paper demonstrates that mixed microbial fermentation can be manipulated to increase VFA production through bioaugmentation.
挥发性脂肪酸（VFA）是具有多种工业用途的化学品，拥有庞大的市场。尽管目前VFA由石化产品生产，但化工行业正朝着更多由木质纤维素生物质等丰富、廉价且可再生资源生产的生物基VFA发展。在本研究中，我们考察了用产乙酸菌进行生物强化对提高木质纤维素发酵过程中VFA产量的影响。本研究的核心假设是，在以木质纤维素生物质水解产物为食的体外瘤胃生物反应器中抑制甲烷生成会增加氢气分压，通过用已知的产乙酸菌进行定向生物强化，该氢气分压可转而用于提高VFA产量，尤其是乙酸产量。在本研究中，先用10 mM的2-溴乙烷磺酸盐（BES）抑制湿爆玉米秸秆瘤胃发酵过程中的甲烷生成，然后在两个单独的生物反应器中分别用[具体菌种1]和[具体菌种2]进行生物强化。在抑制阶段，我们发现添加BES使乙酸产量降低了24%，同时顶空氢气含量从1%增加到60%。生物强化后，两个生物反应器中的顶空氢气均被消耗，添加[具体菌种1]时乙酸浓度增加了45%，添加[具体菌种2]时增加了70%。本文证明了通过生物强化可调控混合微生物发酵以提高VFA产量。
