Universidade Federal de Viçosa, Instituto de Biotecnologia Aplicada à Agropecuária, Departamento de Microbiologia, Campus Universitário, Viçosa, MG, Brazil.
Benef Microbes. 2012 Mar 1;3(1):23-32. doi: 10.3920/BM2011.0037.
There are three main reasons for using lactic acid bacteria (LAB) as starter cultures in industrial food fermentation processes: food preservation due to lactic acid production; flavour formation due to a range of organic molecules derived from sugar, lipid and protein catabolism; and probiotic properties attributed to some strains of LAB, mainly of lactobacilli. The aim of this study was to identify some genes involved in lactose metabolism of the probiotic Lactobacillus delbrueckii UFV H2b20, and analyse its organic acid production during growth in skimmed milk. The following genes were identified, encoding the respective enzymes: ldh - lactate dehydrogenase, adhE - Ldb1707 acetaldehyde dehydrogenase, and ccpA-pepR1 - catabolite control protein A. It was observed that L. delbrueckii UFV H2b20 cultivated in different media has the unexpected ability to catabolyse galactose, and to produce high amounts of succinic acid, which was absent in the beginning, raising doubts about the subspecies in question. The phylogenetic analyses showed that this strain can be compared physiologically to L. delbrueckii subsp. bulgaricus and L. delbrueckii subsp. lactis, which are able to degrade lactose and can grow in milk. L. delbrueckii UFV H2b20 sequences have grouped with L. delbrueckii subsp. bulgaricus ATCC 11842 and L. delbrueckii subsp. bulgaricus ATCC BAA-365, strengthening the classification of this probiotic strain in the NCFM group proposed by a previous study. Additionally, L. delbrueckii UFV H2b20 presented an evolutionary pattern closer to that of probiotic Lactobacillus acidophilus NCFM, corroborating the suggestion that this strain might be considered as a new and unusual subspecies among L. delbrueckii subspecies, the first one identified as a probiotic. In addition, its unusual ability to metabolise galactose, which was significantly consumed in the fermentation medium, might be exploited to produce low-browning probiotic Mozzarella cheeses, a desirable property for pizza cheeses.
使用乳酸菌（LAB）作为工业食品发酵过程中的起始培养物有三个主要原因：由于乳酸的产生而具有食品保存作用；由于糖、脂和蛋白质分解代谢产生的一系列有机分子而形成风味；以及一些 LAB 菌株（主要是乳杆菌）的益生菌特性。本研究的目的是鉴定益生菌德氏乳杆菌 UFV H2b20 乳糖代谢相关的一些基因，并分析其在脱脂乳中生长时的有机酸产生情况。鉴定出以下基因，分别编码相应的酶：ldh - 乳酸脱氢酶、adhE - Ldb1707 乙醛脱氢酶和 ccpA-pepR1 - 分解代谢物控制蛋白 A。结果表明，在不同培养基中培养的德氏乳杆菌 UFV H2b20 具有出人意料的分解半乳糖的能力，并产生大量的琥珀酸，而在开始时琥珀酸并不存在，这使人对所讨论的亚种产生怀疑。系统发育分析表明，该菌株在生理上可与能够降解乳糖并能在牛奶中生长的德氏乳杆菌亚种保加利亚乳杆菌和德氏乳杆菌亚种 lactis 相媲美。德氏乳杆菌 UFV H2b20 的序列与德氏乳杆菌亚种保加利亚乳杆菌 ATCC 11842 和德氏乳杆菌亚种保加利亚乳杆菌 ATCC BAA-365 聚在一起，加强了先前研究提出的 NCFM 组中该益生菌菌株的分类。此外，德氏乳杆菌 UFV H2b20 表现出与益生菌嗜酸乳杆菌 NCFM 更接近的进化模式，这证实了该菌株可能被认为是德氏乳杆菌亚种中一种新的不寻常亚种的建议，这是第一个被鉴定为益生菌的亚种。此外，它具有异常的代谢半乳糖的能力，在发酵培养基中消耗了大量的半乳糖，这可能被用来生产低褐变益生菌马苏里拉奶酪，这是比萨奶酪的理想特性。
