Arginine metabolism by wine Lactobacilli isolated from wine Original Research Article

Lactobacillus hilgardii is a very common heterofermentative bacterium found in wine, associated mainly with several kinds of negative alterations. It is also known as a spoilage organism in soft drinks and other fermented beverages. It is able to break down arginine, one of the most abundant amino acids in wine, through the arginine deiminase (ADI) pathway. The first step of this metabolism may lead to the excretion of citrulline. This feature has an important enological implication since citrulline can react spontaneously with ethanol to form ethyl carbamate. Carcinogenic effects of this compound have been observed when administrated at high concentrations to laboratory animals. To complete the understanding of this catabolic pathway in L. hilgardii, arginine and citrulline utilization were investigated under different conditions. Moreover, ATP production from these amino acids was also monitored. From these data, arginine degradation via the ADI pathway can be considered to be a mechanism of energy production and pH regulation. However, if arginine degradation is beneficial for the bacteria, improving its growing ability and its adaptability, this increases the risk of degradation of the organoleptic and hygienic properties of wine.