Arena Mario E, Manca de Nadra María C
Facultad de Bioquímica, Química y Farmacia, Universidad Nacional de Tucumán, Ayacucho 491, Instituto de Microbiología, 4000 Tucumán, Argentina.
Res Microbiol. 2005 Sep;156(8):858-64. doi: 10.1016/j.resmic.2005.03.010.
The aim of this work was to study the effects of ethanol on cell growth and arginine and citrulline metabolism in two heterofermentative lactic acid bacteria from wine, and to determine their possible association with the formation of ethyl carbamate (EC), a carcinogenic compound. Lactobacillus hilgardii X1B is able to utilize arginine and citrulline, while Oenococcus oeni m can only use citrulline, a precursor of EC. Growth of both microorganisms was partially inhibited by 10 and 15% (v/v) ethanol. Specific arginine consumption by L. hilgardii increased when the pH value diminished from 6.5 to 3.8, but was not affected by an increasing ethanol concentration. However, the ethanol concentration affected the specific citrulline consumption of both microorganisms. Arginine metabolism by L. hilgardii X1B increased the amount of citrulline, thus allowing production of EC in the medium. Citrulline utilization by both microorganisms, at all pH values studied, indirectly inhibited the formation of EC; indeed, one of the precursors had practically disappeared after 48 h of incubation. Due to its ability to form precursors, L. hilgardii X1B has the potential to contribute to EC formation, whereas citrulline utilization by O. oeni m in the presence of ethanol may contribute to diminishing the formation of EC. Rapid degradation of citrulline in the presence of ethanol by O. oeni m is important from a toxicological point of view, because it is important to keep the EC levels as low as possible.
这项工作的目的是研究乙醇对两种来自葡萄酒的异型发酵乳酸菌细胞生长以及精氨酸和瓜氨酸代谢的影响，并确定它们与致癌化合物氨基甲酸乙酯（EC）形成之间的可能关联。希氏乳杆菌X1B能够利用精氨酸和瓜氨酸，而酒类酒球菌m只能利用瓜氨酸，瓜氨酸是EC的前体。10%和15%（v/v）的乙醇对这两种微生物的生长均有部分抑制作用。当pH值从6.5降至3.8时，希氏乳杆菌对精氨酸的特定消耗量增加，但不受乙醇浓度增加的影响。然而，乙醇浓度影响了这两种微生物对瓜氨酸的特定消耗量。希氏乳杆菌X1B的精氨酸代谢增加了瓜氨酸的量，从而使培养基中能够产生EC。在所有研究的pH值下，这两种微生物对瓜氨酸的利用均间接抑制了EC的形成；实际上，在培养48小时后，其中一种前体物质几乎消失。由于其形成前体的能力，希氏乳杆菌X1B有可能促进EC的形成，而酒类酒球菌m在乙醇存在下对瓜氨酸的利用可能有助于减少EC的形成。从毒理学角度来看，酒类酒球菌m在乙醇存在下对瓜氨酸的快速降解很重要，因为将EC水平保持在尽可能低的水平很重要。
