为探究苯扎氯铵（BAC）作为乳制品生产中常用消毒剂的残留对发酵乳中乳酸菌的影响，该文通过宏基因组学解析BAC对乳酸菌基因功能和代谢途径的作用机制。结果表明，从3个不同含量的BAC发酵乳中共检测到216种乳酸菌，以唾液链球菌嗜热亚种为主，占总菌株数的99.78%~98.45%，且BAC对乳酸菌的生长和繁殖具有显著抑制作用。基因功能注释分析显示，COG数据库共注释了16112个基因，对氨基酸转运代谢功能单元影响最高；在KEGG数据库中，碳水化合物和氨基酸代谢为主要代谢途径，随BAC含量增加，基因数量降低了7.76%~9.1%；CAZy分析显示，糖苷水解酶（Glycoside Hydrolases, GHs）和糖基转移酶（Glycosyl Transferases, GTs）丰度最高（占比79.08%~80.38%），且BAC对GT8基因具有显著上调作用。代谢途径差异分析显示，BAC对葡萄糖激酶和丙酮酸激酶具有下调作用，导致BAC2.0样品组产酸能力降低，可能进一步影响发酵乳的质构和风味特性。研究结果为深入理解BAC对乳酸菌的潜在影响提供了重要依据，并为后续探讨BAC在其他发酵食品中潜在风险提供了基础。

To investigate the effects of benzalkonium chloride (BAC), a commonly used disinfectant in dairy production, on lactic acid bacteria (LAB) in fermented milk, this study utilized metagenomic analysis to elucidate the mechanisms by which BAC influences LAB gene functions and metabolic pathways. The results revealed a total of 216 LAB species identified from fermented milk samples containing three different levels of BAC, predominantly Streptococcus salivarius subsp. thermophilus, accounting for 99.78% to 98.45% of the total bacterial strains. BAC significantly inhibited the growth and proliferation of LAB. Gene function annotation analysis showed that 16,112 genes were annotated in the COG database, with the highest impact observed on amino acid transport and metabolism functional units. In the KEGG database, carbohydrate and amino acid metabolism were the primary pathways, with gene counts decreasing by 7.76% to 9.1% as BAC concentration increased. CAZy analysis indicated that glycoside hydrolases (GHs) and glycosyl transferases (GTs) were the most abundant enzyme families (accounting for 79.08% to 80.38%), and BAC significantly upregulated the GT8 gene. Differential metabolic pathway analysis demonstrated that BAC downregulated glucose kinase and pyruvate kinase, resulting in reduced acid production capacity in the BAC2.0 sample group, potentially affecting the texture and flavor characteristics of fermented milk. These findings provide critical insights into the potential impacts of BAC on LAB and lay a foundation for further exploration of BAC-related risks in other fermented foods.

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