基于宏基因测序及分箱技术的复合乳酸菌发酵乳菌种鉴定及定量

Identification and quantification of lactic acid bacteria species in compoundfermented milk based on metagenomic sequencing and binning technique

复合乳酸菌发酵乳产品的菌种组成与定量是产品质量的关键。以3款市售复合乳酸菌发酵乳产品为研究对象,利用宏基因组测序和分箱分析、平均核苷酸一致性(average nucleotide identity,ANI)分析等技术,研究复合乳酸菌发酵乳产品中菌种种水平鉴定及相对定量。结果表明,产品A和产品C分箱获得的3个bin通过ANI分析鉴定为嗜热链球菌(Streptococcus thermophilus)、德氏乳杆菌(Lactobacillus delbrueckii)和动物双歧杆菌(Bifidobacterium animalis),与产品声称添加菌种一致,产品A中3个物种的相对丰度分别为96.85%、0.12%和3.02%,产品C中3个物种的相对丰度分别为99.55%、0.18%和0.14%。产品B分箱获得的3个bin通过ANI分析鉴定为嗜热链球菌(Streptococcus thermophilus)、干酪乳酪杆菌(Lacticaseibacillus casei)和乳酸乳球菌(Lactococcus lactis),与产品声称添加菌种部分一致,3个物种的相对丰度分别为99.43%、0.27%和0.21%。该研究对复合乳酸菌发酵乳产品的质量控制和行业监管具有重要参考意义。

The microbial composition and quantity are essential for the quality of the fermented milk.This study detected the species composition and relative quantification of different lactic acid bacteria in three commercial fermented milk using metagenomic sequencing,binning and average nucleotide identity(ANI)analysis methods.The results showed that,the three bins obtained from product A and product C were identified as Streptococcus thermophilus,Lactobacillus delbrueckii and Bifidobacterium animalis,respectively by ANI analysis,and the identification results were consistent with the product claims of fermented milk.The relative abundances of the three species in product A were 96.85%,0.12%and 3.02%,respectively.The relative abundances of the three species in product C were 99.55%,0.18%and 0.14%,respectively.The three bins obtained for product B were identified as Streptococcus thermophilus,Lacticaseibacillus casei and Lactococcus lactis,and the identification results were partly consistent with the product claims of fermented milk.The relative abundances of the three species were 99.43%,0.27%and 0.21%,respectively.This study provided a scientific basis for the quality control and regulation of fermented milk products with complex bacteria.