Svetlitchnyi Vitali A, Svetlichnaya Tatiana P, Falkenhan Doris A, Swinnen Steve, Knopp Daniela, Läufer Albrecht
BluCon Biotech GmbH, Nattermannallee 1, 50829, Cologne, Germany.
Biotechnol Biofuels Bioprod. 2022 May 2;15(1):44. doi: 10.1186/s13068-022-02137-7.
Consolidated bioprocessing (CBP) of lignocellulosic biomass to L-lactic acid using thermophilic cellulolytic/hemicellulolytic bacteria provides a promising solution for efficient lignocellulose conversion without the need for additional cellulolytic/hemicellulolytic enzymes. Most studies on the mesophilic and thermophilic CBP of lignocellulose to lactic acid concentrate on cultivation of non-cellulolytic mesophilic and thermophilic bacteria at temperatures of 30-55 °C with external addition of cellulases/hemicellulases for saccharification of substrates.
L-Lactic acid was generated by fermenting microcrystalline cellulose or lignocellulosic substrates with a novel thermophilic anaerobic bacterium Caldicellulosiruptor sp. DIB 104C without adding externally produced cellulolytic/hemicellulolytic enzymes. Selection of this novel bacterium strain for lactic acid production is described as well as the adaptive evolution towards increasing the L-lactic acid concentration from 6 to 70 g/l on microcrystalline cellulose. The evolved strains grown on microcrystalline cellulose show a maximum lactic acid production rate of 1.0 g/l*h and a lactic acid ratio in the total organic fermentation products of 96 wt%. The enantiomeric purity of the L-lactic acid generated is 99.4%. In addition, the lactic acid production by these strains on several other types of cellulose and lignocellulosic feedstocks is also reported.
The evolved strains originating from Caldicellulosiruptor sp. DIB 104C were capable of producing unexpectedly large amounts of L-lactic acid from microcrystalline cellulose in fermenters. These strains produce L-lactic acid also from lignocellulosic feedstocks and thus represent an ideal starting point for development of a highly integrated commercial L-lactic acid production process from such feedstocks.
利用嗜热纤维素分解/半纤维素分解细菌将木质纤维素生物质整合生物加工（CBP）为L-乳酸，为高效木质纤维素转化提供了一种有前景的解决方案，无需额外的纤维素分解/半纤维素分解酶。大多数关于将木质纤维素中温及嗜热CBP转化为乳酸的研究集中在30-55°C温度下培养非纤维素分解中温及嗜热细菌，并外加纤维素酶/半纤维素酶用于底物糖化。
用一种新型嗜热厌氧细菌嗜热纤维梭菌属DIB 104C发酵微晶纤维素或木质纤维素底物，无需添加外源产生的纤维素分解/半纤维素分解酶即可产生L-乳酸。描述了选择该新型菌株用于乳酸生产的过程，以及在微晶纤维素上使L-乳酸浓度从6 g/L提高到70 g/L的适应性进化。在微晶纤维素上生长的进化菌株显示出最大乳酸生产率为1.0 g/L·h，且在总有机发酵产物中乳酸比例为96 wt%。所产生的L-乳酸的对映体纯度为99.4%。此外，还报道了这些菌株在其他几种类型的纤维素和木质纤维素原料上的乳酸生产情况。
源自嗜热纤维梭菌属DIB 104C的进化菌株能够在发酵罐中从微晶纤维素中意外地大量生产L-乳酸。这些菌株也能从木质纤维素原料中生产L-乳酸，因此代表了从这类原料开发高度集成的商业化L-乳酸生产工艺的理想起点。
