Liu Huifang, Liu Xiumei, Jiang Hong, Liang Changhui, Zhang Z Conrad
State Key Laboratory of Catalysis, Dalian National Laboratory for Clean Energy, Dalian Key Laboratory of Energy Biotechnology, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China.
University of Chinese Academy of Sciences, Beijing, 100049, China.
Bioprocess Biosyst Eng. 2021 Oct;44(10):2153-2166. doi: 10.1007/s00449-021-02591-x. Epub 2021 May 31.
Expensive cellulase and complex detoxification procedures increase the cost of biomass lactic acid fermentation. Therefore, it is of great significance to develop a robust method to ferment lactic acid using biomass by avoiding cellulase and detoxification. This study demonstrates the advantage of combining mechanocatalytic PO pre-treatment and strain domestication. We show that an enzyme-free mechanocatalytic saccharification process by combining mix-milling of PO with biomass and successive hydrolysis produces a fermentable hydrolysate with much less inhibitory compounds than the hydrolysates obtained by conventional methods; only 5-HMF, furfural and acetic acid were detected in the biomass hydrolysate, and no phenolic inhibitors were detected. Pretreatment of biomass with PO not only avoided cellulase, but also obtained less toxic hydrolysate. Furthermore, the Pediococcus pentosaceus strain gained superior inhibitor tolerance through domestication. It could tolerate 17.1 g/L acetic acid, 12.5 g/L 5-HMF, 11.9 g/L guaiacol and 11.5 g/L furfural and showed activity in decomposing furfural and 5-HMF for self-detoxification, allowing efficient lactic acid fermentation from biomass hydrolysate without detoxification. The lactic acid concentration and conversion rate fermented by domesticated bacteria were increased by 113.5% and 22.4%, respectively. In addition, the domesticated bacteria could utilize glucose and xylose simultaneously to produce lactic acid selectively. The combination of PO pre-treatment and strain domestication to ferment lactic acid is applied to several biomass feedstocks, including corn stalk, corn stalk residue and rice husk residue. Lactic acid concentrations of 29.8 g/L, 31.1 g/L, and 46.2 g/L were produced from the hydrolysates of corn stalk, corn stalk residue and rice husk residue, respectively.
昂贵的纤维素酶和复杂的解毒程序增加了生物质乳酸发酵的成本。因此，开发一种通过避免使用纤维素酶和解毒来利用生物质发酵乳酸的可靠方法具有重要意义。本研究证明了机械催化磷酸预处理和菌株驯化相结合的优势。我们表明，通过将磷酸与生物质混合研磨并连续水解相结合的无酶机械催化糖化过程产生的可发酵水解产物中抑制性化合物比传统方法获得的水解产物少得多；在生物质水解产物中仅检测到5-羟甲基糠醛、糠醛和乙酸，未检测到酚类抑制剂。用磷酸对生物质进行预处理不仅避免了纤维素酶的使用，还获得了毒性较小的水解产物。此外，戊糖片球菌菌株通过驯化获得了更高的抑制剂耐受性。它可以耐受17.1克/升乙酸、12.5克/升5-羟甲基糠醛、11.9克/升愈创木酚和11.5克/升糠醛，并在分解糠醛和5-羟甲基糠醛以进行自我解毒方面表现出活性，从而允许在不解毒的情况下从生物质水解产物中高效发酵乳酸。驯化后的细菌发酵的乳酸浓度和转化率分别提高了113.5%和22.4%。此外，驯化后的细菌可以同时利用葡萄糖和木糖选择性地生产乳酸。磷酸预处理和菌株驯化相结合发酵乳酸的方法应用于几种生物质原料，包括玉米秸秆、玉米秸秆残渣和稻壳残渣。从玉米秸秆、玉米秸秆残渣和稻壳残渣的水解产物中分别产生了29.8克/升、31.1克/升和46.2克/升的乳酸浓度。
