Alexandri Maria, Hübner Dennis, Schneider Roland, Fröhling Antje, Venus Joachim
Leibniz Institute for Agricultural Engineering and Bioecomomy (ATB), Max-Eyth Allee 100, Potsdam, Germany; Ionian University, Department of Food Science and Technology, Argostoli 28100, Kefalonia, Greece.
Leibniz Institute for Agricultural Engineering and Bioecomomy (ATB), Max-Eyth Allee 100, Potsdam, Germany.
N Biotechnol. 2022 Dec 25;72:1-10. doi: 10.1016/j.nbt.2022.08.003. Epub 2022 Aug 15.
This study presents the production of D-lactic acid with high enantiomeric purity using lignocellulosic hydrolysates from newly isolated lactic acid bacterial (LAB) strains. Six strains, 4 heterofermentative and 2 homofermentative, were investigated for their ability to grow and produce lactic acid on sugar beet pulp (SBP) hydrolysates, containing a mixture of hexose and pentose sugars. Among the strains tested, three were isolates designated as A250, A257 and A15, all of which belonged to the genus Leuconostoc. Only strain A250 could be reliably identified as Leuconostoc pseudomesenteroides based on cluster analysis of Maldi-ToF spectra. All strains produced D-lactic acid in the presence of SBP hydrolysates, but with varying optical purities. The homofermentative strains achieved higher D-lactic acid optical purities, but without assimilating the pentose sugars. Co-cultivation of the homofermentative strain Lactobacillus coryniformis subsp. torquens DSM 20005 together with the heterofermentative isolate A250 led to the production of 21.7 g/L D-lactic acid with 99.3 % optical purity. This strategy enabled the complete sugar utilization of the substrate. Nanofiltration of the SBP hydrolysate enhanced the enantiomeric purity of the D-lactic acid produced from the isolates A250 and A15 by about 5 %. The highest D-lactic acid concentration (40 g/L) was achieved in fed-batch cultures of A250 isolate with nanofiltered SBP, where optical purity was 99.4 %. The results of this study underline the feasibility of a novel isolate as an efficient D-lactic acid producer using lignocellulosic hydrolysates.
本研究介绍了利用新分离的乳酸菌（LAB）菌株的木质纤维素水解产物生产对映体纯度高的D-乳酸。研究了6株菌株，其中4株为异型发酵菌，2株为同型发酵菌，考察它们在含有己糖和戊糖混合物的甜菜浆（SBP）水解产物上生长和产乳酸的能力。在所测试的菌株中，有3株分离株，分别命名为A250、A257和A15，它们均属于明串珠菌属。基于基质辅助激光解吸电离飞行时间（Maldi-ToF）光谱的聚类分析，只有菌株A250能被可靠地鉴定为类肠系膜明串珠菌。在SBP水解产物存在的情况下，所有菌株均产D-乳酸，但光学纯度各不相同。同型发酵菌株获得了更高的D-乳酸光学纯度，但不能同化戊糖。将同型发酵菌株棒状乳杆菌torquens亚种DSM 20005与异型发酵分离株A250共培养，可生产出21.7 g/L的D-乳酸，光学纯度为99.3%。该策略使底物中的糖得以完全利用。对SBP水解产物进行纳滤，可使分离株A250和A15产生的D-乳酸的对映体纯度提高约5%。在使用纳滤SBP对A250分离株进行补料分批培养时，获得了最高的D-乳酸浓度（40 g/L），此时光学纯度为99.4%。本研究结果强调了利用木质纤维素水解产物将新型分离株作为高效D-乳酸生产者的可行性。
