Bonnarme P, Lapadatescu C, Yvon M, Spinnler H E
Institut National de la Recherche Agronomique, Laboratoire de Génie et Microbiologie des Procédés Alimentaires, Thiverval-Grignon, France.
J Dairy Res. 2001 Nov;68(4):663-74. doi: 10.1017/s002202990100509x.
Volatile sulphur compounds are major flavouring compounds in many traditional fermented foods including cheeses. These compounds are products of the catabolism of L-methionine by cheese-ripening microorganisms. The diversity of L-methionine degradation by such microorganisms, however, remains to be characterized. The objective of this work was to compare the capacities to produce volatile sulphur compounds by five yeasts, Geotrichum candidum, Yarrowia lipolytica, Kluyveromyces lactis, Debaryomyces hansenii, Saccharomyces cerevisiae and five bacteria, Brevibacterium linens, Corynebacterium glutamicum, Arthrobacter sp., Micrococcus lutens and Staphylococcus equorum of technological interest for cheese-ripening. The ability of whole cells of these microorganisms to generate volatile sulphur compounds from L-methionine was compared. The microorganisms produced a wide spectrum of sulphur compounds including methanethiol, dimethylsulfide, dimethyldisulfide, dimethyltrisulfide and also S-methylthioesters, which varied in amount and type according to strain. Most of the yeasts produced methanethiol, dimethylsulfide, dimethyldisulfide and dimethyltrisulfide but did not produce S-methylthioesters, apart from G. candidum that produced S-methyl thioacetate. Bacteria, especially Arth. sp. and Brevi. linens, produced the highest amounts and the greatest variety of volatile sulphur compounds includling methanethiol, sulfides and S-methylthioesters, e.g. S-methyl thioacetate, S-methyl thiobutyrate, S-methyl thiopropionate and S-methyl thioisovalerate. Cell-free extracts of all the yeasts and bacteria were examined for the activity of enzymes possibly involved in L-methionine catabolism, i.e. L-methionine demethiolase, L-methionine aminotransferase and L-methionine deaminase. They all possessed L-methionine demethiolase activity, while some (K. lactis, Deb. hansenii, Arth. sp., Staph. equorum) were deficient in L-methionine aminotransferase, and none produced L-methionine deaminase. The catabolism of L-methionine in these microorganisms is discussed.
挥发性硫化合物是包括奶酪在内的许多传统发酵食品中的主要风味化合物。这些化合物是奶酪成熟微生物对L-甲硫氨酸进行分解代谢的产物。然而，此类微生物对L-甲硫氨酸降解的多样性仍有待表征。这项工作的目的是比较五种酵母（白地霉、解脂耶氏酵母、乳酸克鲁维酵母、汉逊德巴利酵母、酿酒酵母）和五种细菌（亚麻短杆菌、谷氨酸棒杆菌、节杆菌属、藤黄微球菌、马胃葡萄球菌）产生挥发性硫化合物的能力，这些微生物对奶酪成熟具有技术意义。比较了这些微生物的全细胞从L-甲硫氨酸生成挥发性硫化合物的能力。这些微生物产生了广泛的硫化合物，包括甲硫醇、二甲基硫醚、二甲基二硫醚、二甲基三硫醚以及S-甲硫酯，其数量和类型因菌株而异。大多数酵母产生甲硫醇、二甲基硫醚、二甲基二硫醚和二甲基三硫醚，但不产生S-甲硫酯，除了产生S-甲硫乙酸酯的白地霉。细菌，尤其是节杆菌属和亚麻短杆菌，产生了最高数量和最多样化类型的挥发性硫化合物，包括甲硫醇、硫化物和S-甲硫酯，例如S-甲硫乙酸酯、S-甲硫丁酸酯、S-甲硫丙酸酯和S-甲硫异戊酸酯。检测了所有酵母和细菌的无细胞提取物中可能参与L-甲硫氨酸分解代谢的酶的活性，即L-甲硫氨酸脱甲硫醇酶、L-甲硫氨酸转氨酶和L-甲硫氨酸脱氨酶。它们都具有L-甲硫氨酸脱甲硫醇酶活性，而一些（乳酸克鲁维酵母、汉逊德巴利酵母、节杆菌属、马胃葡萄球菌）缺乏L-甲硫氨酸转氨酶活性，并且均不产生L-甲硫氨酸脱氨酶。本文讨论了这些微生物中L-甲硫氨酸的分解代谢。
