乳酸乳球菌乳酸亚种的^(m6)A甲基化差异研究

Studies on the Difference about N6-Methyladenine Methylation of Lactococcus lactis subsp.lactis

乳酸乳球菌乳酸亚种是常用的工业发酵剂菌种,具有较高的经济价值。乳酸乳球菌乳酸亚种BL19与IMAU10978的发酵特性存在较大差异,其中BL19具有良好发酵特性。本文比较2株存在明显发酵特性差异的乳酸乳球菌乳酸亚种BL19与IMAU10978,从基因组与^(m6)A甲基化角度探究2株菌的发酵差异化特性。通过单分子实时(SMRT)测序技术对BL19与IMAU10978进行全基因组测序与^(m6)A甲基化鉴定,并结合NCBI全基因组数据,比较不同菌株的功能基因差异和BL19与IMAU10978的^(m6)A甲基化差异。比较基因组分析表明:试验菌株的平均核苷酸一致性高达98.24%,且其功能基因不存在明显差异,均以碳水化合物和氨基酸代谢等为主。甲基化分析显示:IMAU10978与BL19的肽转运载体、PTS系统和2,3-丁二醇脱氢酶等相关基因的^(m6)A甲基化存在明显差异。本研究分析了BL19与IMAU10978的基因组与^(m6)A甲基化,发现2株菌的亲缘关系近且功能基因较为相似,^(m6)A甲基化差异可能是导致发酵特性差异的重要原因。此外,还初步探究工业发酵剂菌株基因组的表观修饰,为工业菌株的选育提供了理论基础。

Lactococcus(L.)lactis subsp.lactis is a common industrial starter strain with high economic value.The fermentation characteristics of L.lactis subsp.lactis BL19 and IMAU10978 are quite different,and Bl19 has good fermentation characteristics.The purpose of this study was to compare L.lactis subsp.lactis BL19 and IMAU10978,which have significant differences in fermentation characteristics,and explore the causes of differences in fermentation characteristics from the perspective of genome and ^(m6)A methylation.We sequenced the whole genome of BL19 and IMAU10978 and identified their ^(m6)A methylation by PacBio SMRT sequencing technology.Combined with NCBI genome data,we analyzed the functional gene differences of different strains and the ^(m6)A methylation differences between BL19 and IMAU10978.Comparative genomics analysis showed that the average nucleotide identity of the experimental strains was 98.24%,and their functional genes which had no obvious difference,were mainly carbohydrate,amino acid metabolism and so on.Methylation analysis showed that there were obvious differences between BL19 and IMAU10978 in ^(m6)A methylation of gene associated with peptide transporter,PTS system,2,3-butanediol dehydrogenase and so on.We analyzed the genome and ^(m6)A methylation of BL19 and IMAU10978.And we found that the two strains had close relationship and the functional genes of them were roughly similar.Therefore,the ^(m6)A methylation difference may be an important reason for the difference of their fermentation characteristics.We explored the epigenetic modification of the genome of industrial starter strains preliminarily,which provided a theoretical basis for the selection of industrial strains.