Institute of Biology Bucharest of the Romanian Academy, Bucharest, Romania.
Institute of Biochemistry of the Romanian Academy - IBRA, Bucharest, Romania.
World J Microbiol Biotechnol. 2022 Sep 9;38(12):220. doi: 10.1007/s11274-022-03408-z.
Traditionally fermented foods and beverages are still produced and consumed at a large scale in Romania. They are rich sources for novel lactic acid bacteria with functional properties and with potential application in food industry or health. Lactobacillus helveticus 34.9, isolated from a home-made fermented milk is able to inhibit the growth of other bacteria, such as other lactic acid bacteria, but also strains of Bacillus subtilis, Bacillus cereus, Staphylococcus aureus, and Halobacillus hunanensis, a halobacterium isolated from the degraded wall of a Romanian monastery. L. helveticus 34.9 produces a large bacteriocin (35 KDa), active in a wide pH range, but inactivated by heat and proteinase K treatment. It shares about 20% sequence coverage with helveticin J, as determined by LC-MS analysis. Bacteriocin production was enhanced under stress conditions, especially when combined stresses were applied. Its mode of action and degree of inhibition depended on the concentration and on the indicator strain that was used; L. delbrueckii subsp. bulgaricus LMG 6901 cells from a suspension were killed, but the viability of H. hunanensis 5Hum cells was only reduced to 60%, within 8 h. However, the bacteriocin was able to prevent the bacterial growth of both indicator strains when added to the cultivation medium prior inoculation. Scanning electron microscopy images revealed morphological changes induced by the bacteriocin treatment in both sensitive strains, but more severe in the case of L. delbrueckii subsp. bulgaricus. Due to the broad antibacterial spectrum and its production under various stress conditions, the bacteriocin or the producing strain may find application in health, food and non-food related fields, including in the restoration of historical buildings.
传统发酵食品和饮料在罗马尼亚仍大规模生产和消费。它们是具有功能特性的新型乳酸菌的丰富来源，具有在食品工业或健康领域应用的潜力。从自制发酵乳中分离出的瑞士乳杆菌 34.9 能够抑制其他细菌的生长，如其他乳酸菌，以及枯草芽孢杆菌、蜡状芽孢杆菌、金黄色葡萄球菌和嗜盐菌的生长，嗜盐菌是从罗马尼亚一座修道院的退化墙壁中分离出来的一种嗜盐菌。瑞士乳杆菌 34.9 产生一种大的细菌素（35 kDa），在较宽的 pH 范围内具有活性，但热和蛋白酶 K 处理会使其失活。通过 LC-MS 分析，它与 helveticin J 约有 20%的序列覆盖率。在应激条件下，特别是当应用复合应激时，细菌素的产生会增强。其作用模式和抑制程度取决于浓度和所用的指示菌株；悬浮液中的德氏乳杆菌保加利亚亚种 LMG 6901 细胞被杀死，但 5Hum 细胞的活力仅降低到 60%，在 8 小时内。然而，当在接种前添加到培养液中时，细菌素能够防止两种指示菌株的细菌生长。扫描电子显微镜图像显示了在敏感菌株中，细菌素处理诱导的形态变化，但在德氏乳杆菌保加利亚亚种中更为严重。由于广谱抗菌谱和在各种应激条件下的生产，细菌素或产生菌株可能在健康、食品和非食品相关领域找到应用，包括在历史建筑的修复中。
