氯化钠添加量对牦牛乳硬质干酪中微生物群落演变的影响

Effects of Sodium Chloride Addition on Microbial Community Evolution of Yak Milk Hard Cheese

摘要:

【目的】探明氯化钠添加量对牦牛乳硬质干酪微生物群落的调控机制。【方法】采用高通量测序技术，在氯化钠添加质量分数分别为1.0%、1.3%、1.8%、2.3%条件下，分析干酪在0~6个月成熟期间的微生物群落演变特征。【结果】随着氯化钠添加质量分数减少，干酪中链球菌属（Streptococcus）相对丰度先升后降，乳球菌属（Lactococcus）相对丰度缓慢上升，埃舍里希亚-志贺氏菌属（Escherichia-Shigella）相对丰度呈上升趋势，乳杆菌属（Lactobacillus）相对丰度整体降低，魏斯氏菌属（Weissella）相对丰度快速下降，不动杆菌属（Acinetobacter）、金黄杆菌属（Chryseobacterium）、假单胞菌属（Pseudomonas）相对丰度先降后升。氯化钠添加质量分数为2.3%时，干酪以Lactobacillus、Weissella为特征差异菌属，且相对丰度高于其他组；氯化钠添加质量分数为1.0%时，干酪中Lactococcus、Acinetobacter、Chryseobacterium、Pseudomonas为特征差异菌属，其中后三者相对丰度较氯化钠添加质量分数为2.3%时增幅明显；氯化钠添加质量分数为1.3%时，这3个菌属相对丰度较氯化钠添加质量分数1.0%处理组大幅下降，并在氯化钠添加质量分数1.8%组中降至最低。【结论】通过优化发酵剂组成、控制原料乳质量、适度降盐及添加适配有益菌等工艺，实现低盐牦牛乳硬质干酪的安全性与品质提升。

Abstract:

[Objective]To investigate the regulatory mechanism of sodium chloride sodium chloride addition level on the microbial community in yak milk hard cheese.[Method]High-throughput sequencing technology was employed to analyze the evolution of microbial communities after the addition of sodium chloride at mass fractions of 1.0%, 1.3%, 1.8%, and 2.3% during the 0~6 month maturation period.[Result]As the sodium chloride addition mass fraction decreased, the Streptococcus in the cheese first increased and then decreased, which was accompanied by a slow increase in the relative abundance of Lactococcus, an upward trend in the relative abundance of Escherichia-Shigella, an overall downward trend in the relative abundance of Lactobacillus, and a rapid decreasing trend in the relative abundance of Weissella. In addition, the relative abundance of Acinetobacter, Chryseobacterium, and Pseudomonas first decreased and then increased. In the cheese with sodium chloride added at the mass fraction of 2.3%, Lactobacillus and Weissella were the characteristic differential bacterium genus, with their relative abundance being higher than that in other groups. In the cheese with sodium chloride added at the mass fraction of 1.0%, the characteristic differential bacterium genus were Lactococcus, Acinetobacter, Chryseobacterium, and Pseudomonas. Among them, the latter three genera showed evident increases in relative abundance compared with those in the cheese with sodium chloride added at the mass fraction of 2.3%. Their relative abundance was markedly lower in the cheese with sodium chloride added at the mass fraction of 1.3% than in the cheese with sodium chloride added at the mass fraction of 1.0%, and reached the lowest levels in the cheese with sodium chloride added at the mass fraction of 1.8%.[Conclusion]The safety and quality of low-salt yak milk hard cheese can be improved by optimizing starter cultures, controlling the quality of raw milk, moderately reducing the salt content, and inoculating appropriate beneficial bacteria.