Abstract We investigated the expression profiles of proteolysis-related genes in Lactobacillus paracasei EG9, a non-starter lactic acid bacterial strain used as an adjunct starter in Gouda-type cheese production. The amino acid sequences of previously reported proteolytic enzymes in lactic acid bacteria were matched against the EG9 genome by translated BLAST search, and 31 candidate genes, including those coding for peptidases, oligopeptide transporters, and cell-envelope proteinases, were listed. The relative expression levels of these genes were evaluated at 0 and 30 days of cheese ripening. On day 0, 27 genes showed significantly up-regulated expression compared with the genes in the stationary phase of the reference cultured cells. On day 30, 25 genes were found to be significantly down-regulated. Our findings suggest that the proteolysis-related genes in EG9 play an important role in the proteolytic process from casein degradation through peptide uptake to free amino acid production during cheesemaking.

中文翻译：

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干酪乳杆菌EG9（一种非起始乳酸菌株）在高达型奶酪成熟过程中牛奶蛋白水解相关基因的表达谱

摘要 我们研究了副干酪乳杆菌 EG9 中蛋白水解相关基因的表达谱，这是一种在高达型奶酪生产中用作辅助发酵剂的非发酵乳酸菌株。先前报道的乳酸菌蛋白水解酶的氨基酸序列通过翻译 BLAST 搜索与 EG9 基因组匹配，并列出了 31 个候选基因，包括编码肽酶、寡肽转运蛋白和细胞包膜蛋白酶的基因。在奶酪成熟的第 0 天和第 30 天评估这些基因的相对表达水平。在第 0 天，与参考培养细胞静止期的基因相比，27 个基因的表达显着上调。在第 30 天，发现 25 个基因显着下调。