Berlowska Joanna, Cieciura Weronika, Borowski Sebastian, Dudkiewicz Marta, Binczarski Michal, Witonska Izabela, Otlewska Anna, Kregiel Dorota
Institute of Fermentation Technology and Microbiology, Lodz University of Technology, Wolczanska 171/173, 90-924 Lodz, Poland.
Institute of General and Ecological Chemistry, Lodz University of Technology, Zeromskiego 116, 90-924 Lodz, Poland.
Molecules. 2016 Oct 17;21(10):1380. doi: 10.3390/molecules21101380.
Research into fermentative production of lactic acid from agricultural by-products has recently concentrated on the direct conversion of biomass, whereby pure sugars are replaced with inexpensive feedstock in the process of lactic acid production. In our studies, for the first time, the source of carbon used is sugar beet pulp, generated as a by-product of industrial sugar production. In this paper, we focus on the simultaneous saccharification of lignocellulosic biomass and fermentation of lactic acid, using mixed cultures with complementary assimilation profiles. Lactic acid is one of the primary platform chemicals, and can be used to synthesize a wide variety of useful products, including green propylene glycol. A series of controlled batch fermentations was conducted under various conditions, including pretreatment with enzymatic hydrolysis. Inoculation was performed in two sequential stages, to avoid carbon catabolite repression. Biologically-synthesized lactic acid was catalytically reduced to propylene glycol over 5% Ru/C. The highest lactic acid yield was obtained with mixed cultures. The yield of propylene glycol from the biological lactic acid was similar to that obtained with a water solution of pure lactic acid. Our results show that simultaneous saccharification and fermentation enables generation of lactic acid, suitable for further chemical transformations, from agricultural residues.
近期，利用农业副产品发酵生产乳酸的研究主要集中在生物质的直接转化上，即在乳酸生产过程中用廉价原料替代纯糖。在我们的研究中，首次使用工业制糖的副产品甜菜粕作为碳源。本文聚焦于利用具有互补同化特性的混合培养物，实现木质纤维素生物质的同步糖化和乳酸发酵。乳酸是一种主要的平台化学品，可用于合成多种有用产品，包括绿色丙二醇。在包括酶解预处理在内的各种条件下进行了一系列受控分批发酵。接种分两个连续阶段进行，以避免碳分解代谢物阻遏。生物合成的乳酸在5% Ru/C上催化还原为丙二醇。混合培养物获得了最高的乳酸产量。由生物乳酸制得的丙二醇产率与用纯乳酸水溶液制得的产率相似。我们的结果表明，同步糖化发酵能够从农业残留物中生成适合进一步化学转化的乳酸。
