He Yaxue, Lens Piet N L, Veiga María C, Kennes Christian
Chemical Engineering Laboratory, Faculty of Sciences and Center for Advanced Scientific Research (CICA), BIOENGIN Group, University of La Coruña (UDC), A Coruña, Spain.
National University of Ireland Galway, Galway, Ireland.
Front Bioeng Biotechnol. 2022 Feb 16;10:828316. doi: 10.3389/fbioe.2022.828316. eCollection 2022.
Butanol is a potential renewable fuel. To increase the selectivity for butanol during CO fermentation, exogenous acetic acid and ethanol, exogenous butyric acid or endogenous butyric acid from glucose fermentation have been investigated using CO as reducing power, with a highly enriched sludge. Addition of 3.2 g/L exogenous butyric acid led to the highest 1.9 g/L butanol concentration with a conversion efficiency of 67%. With exogenous acetate and ethanol supply, the butanol concentration reached 1.6 g/L at the end of the incubation. However, the presence of acetic acid and ethanol favoured butanol production to 2.6 g/L from exogenous butyric acid by the enriched sludge. Finally, exogenous 14 g/L butyric acid yielded the highest butanol production of 3.4 g/L, which was also among the highest butanol concentration from CO/syngas fermentation reported so far. CO addition triggered butanol production from endogenous butyric acid (produced from glucose, Glucose + N) with as high as 58.6% conversion efficiency and 62.1% butanol yield. However, no efficient butanol production was found from glucose and CO co-fermentation (Glucose + CO), although a similar amount of endogenous butyric acid was produced compared to Glucose + N. The genus occupied a relative abundance as high as 82% from the initial inoculum, while the and classes were both enriched and dominated in Glucose + N and Glucose + CO incubations. This study shows that the supply of butyric acid is a possible strategy for enhancing butanol production by CO fed anaerobic sludge, either via exogenous butyric acid, or via endogenous production by sugar fermentation.
丁醇是一种潜在的可再生燃料。为了提高一氧化碳发酵过程中丁醇的选择性，人们使用一氧化碳作为还原力，以高度富集的污泥为原料，研究了外源乙酸和乙醇、外源丁酸或葡萄糖发酵产生的内源丁酸。添加3.2 g/L外源丁酸可使丁醇浓度达到最高的1.9 g/L，转化效率为67%。在添加外源乙酸盐和乙醇的情况下，培养结束时丁醇浓度达到1.6 g/L。然而，乙酸和乙醇的存在有利于富集污泥将外源丁酸转化为2.6 g/L的丁醇。最后，添加14 g/L外源丁酸时丁醇产量最高，达到3.4 g/L，这也是迄今为止报道的一氧化碳/合成气发酵中丁醇浓度最高的情况之一。添加一氧化碳可引发内源丁酸（由葡萄糖、葡萄糖+氮产生）产生丁醇，转化效率高达58.6%，丁醇产率为62.1%。然而，尽管与葡萄糖+氮相比产生的内源丁酸量相似，但在葡萄糖和一氧化碳共发酵（葡萄糖+一氧化碳）过程中未发现高效的丁醇生产。初始接种物中该属的相对丰度高达82%，而在葡萄糖+氮和葡萄糖+一氧化碳培养中，该类和该类均得到富集并占主导地位。这项研究表明，提供丁酸是通过一氧化碳喂养的厌氧污泥提高丁醇产量的一种可能策略，无论是通过外源丁酸，还是通过糖发酵的内源生产。
