Spano G, Massa S
Department of Food Science, Foggia University, via Napoli 25, 71100 Foggia, Italy.
Crit Rev Microbiol. 2006;32(2):77-86. doi: 10.1080/10408410600709800.
Lactic acid bacteria (LAB) constitute a heterogeneous group of bacteria that are traditionally used to produce fermented foods. The industrialization of food transformations has increased the economical importance of LAB, as they play a crucial role in the development of the organoleptic and hygienic quality of fermented products. However, the strains selected for industrial purposes, should tolerate adverse conditions encountered in industrial processes, either during starter handling and storage (freeze-drying, freezing, or spray-drying) or during food processing in which abiotic stresses such as heat, cold, acidity, and high concentration of NaCl or ethanol are common. Wine LAB have to deal with several stresses including an acidic pH, a high alcoholic content, non optimal growth temperatures, and growth-inhibitory compounds such as fatty acids and tannins, originated from yeast and bacteria metabolism. Wine LAB have developed several mechanisms to escape or to tolerate wine conditions. They carry out a malolactic fermentation in this stressful environment. In addition to the regulation of the expression of specific genes, bacteria have evolved adaptive networks to face the challenges of a changing environment and to survive under conditions of stress. The so called Global Regulatory Systems control the simultaneous expression of a large number of genes in response to a variety of environmental stress factors. CIRCE sequences able to bind the HrcA repressor, sigma(B) dependent promoters and CtsR regulatory elements have been observed in several genes identified from wine LAB. Improved knowledge of regulators and a better understanding of LAB stress responses could constitute a basis of comparison with the well known model microorganisms, Escherichia coli and Bacillus subtilis. Moreover, it can provide an important insight into improving current industrial starter strains.
乳酸菌（LAB）是一类具有多样性的细菌，传统上用于生产发酵食品。食品加工的工业化提高了乳酸菌的经济重要性，因为它们在发酵产品的感官和卫生品质发展中起着关键作用。然而，为工业目的选择的菌株应能耐受工业过程中遇到的不利条件，无论是在发酵剂处理和储存期间（冷冻干燥、冷冻或喷雾干燥），还是在食品加工过程中，其中热、冷、酸度以及高浓度的氯化钠或乙醇等非生物胁迫很常见。葡萄酒乳酸菌必须应对多种胁迫，包括酸性pH值、高酒精含量、非最适生长温度以及源自酵母和细菌代谢的脂肪酸和单宁等生长抑制化合物。葡萄酒乳酸菌已发展出多种机制来逃避或耐受葡萄酒环境。它们在这种压力环境下进行苹果酸乳酸发酵。除了调节特定基因的表达外，细菌还进化出适应性网络来应对不断变化的环境挑战并在胁迫条件下生存。所谓的全局调控系统控制大量基因对各种环境胁迫因素的同时表达。在从葡萄酒乳酸菌中鉴定出的几个基因中，已观察到能够结合HrcA阻遏物、依赖sigma(B)的启动子和CtsR调控元件的CIRCE序列片段。对调控因子的深入了解以及对乳酸菌应激反应的更好理解，可以构成与著名模式微生物大肠杆菌和枯草芽孢杆菌进行比较的基础。此外，它可以为改进当前的工业发酵剂菌株提供重要的见解。
