Sun Liang, Lu Zhilong, Li Jianxiu, Sun Feifei, Huang Ribo
College of Life Science and Technology, Guangxi University, Nanning, Guangxi, 530004, China.
State Key Laboratory of Non-Food Biomass and Enzyme Technology, National Engineering Research Center for Non-Food Biorefinery, Guangxi Key Laboratory of Biorefinery, Guangxi Academy of Sciences, Nanning, Guangxi, 530007, China.
Mol Genet Genomics. 2018 Feb;293(1):265-276. doi: 10.1007/s00438-017-1379-0. Epub 2017 Nov 20.
Mechanisms for high L-lactic acid production remain unclear in many bacteria. Lactobacillus rhamnosus SCT-10-10-60 was previously obtained from L. rhamnosus ATCC 11443 via mutagenesis and showed improved L-lactic acid production. In this study, the genomes of strains SCT-10-10-60 and ATCC 11443 were sequenced. Both genomes are a circular chromosome, 2.99 Mb in length with a GC content of approximately 46.8%. Eight split genes were identified in strain SCT-10-10-60, including two LytR family transcriptional regulators, two Rex redox-sensing transcriptional repressors, and four ABC transporters. In total, 60 significantly up-regulated genes (logfold-change ≥ 2) and 39 significantly down-regulated genes (logfold-change ≤ - 2) were identified by a transcriptome comparison between strains SCT-10-10-60 and ATCC 11443. KEGG pathway enrichment analysis revealed that "pyruvate metabolism" was significantly different (P < 0.05) between the two strains. The split genes and the differentially expressed genes involved in the "pyruvate metabolism" pathway are probably responsible for the increased L-lactic acid production by SCT-10-10-60. The genome and transcriptome sequencing information and comparison of SCT-10-10-60 with ATCC 11443 provide insights into the anabolism of L-lactic acid and a reference for improving L-lactic acid production using genetic engineering.
许多细菌中高L-乳酸产量的机制仍不清楚。鼠李糖乳杆菌SCT-10-10-60先前通过诱变从鼠李糖乳杆菌ATCC 11443获得，并显示出L-乳酸产量有所提高。在本研究中，对菌株SCT-10-10-60和ATCC 11443的基因组进行了测序。两个基因组均为环状染色体，长度为2.99 Mb，GC含量约为46.8%。在菌株SCT-10-10-60中鉴定出8个分裂基因，包括两个LytR家族转录调节因子、两个Rex氧化还原感应转录抑制因子和四个ABC转运蛋白。通过菌株SCT-10-10-60和ATCC 11443之间的转录组比较，总共鉴定出60个显著上调基因（对数变化≥2）和39个显著下调基因（对数变化≤-2）。KEGG通路富集分析表明，两株菌之间“丙酮酸代谢”存在显著差异（P<0.05）。参与“丙酮酸代谢”途径的分裂基因和差异表达基因可能是SCT-10-10-60中L-乳酸产量增加的原因。SCT-10-10-60与ATCC 11443的基因组和转录组测序信息及比较为L-乳酸的合成代谢提供了见解，并为利用基因工程提高L-乳酸产量提供了参考。
