Grapes are the largest fruit crop worldwide. Globally, half of the harvested grapes are turned into wine, and the sector is of great economic importance for the European Union. The transformation of grapes into wine is a multi-step process that relies on specific metabolic processes carried out by the resident microbiota. One widely represented group consists of lactic acid bacteria, which includes various species that are feared for their potential to alter the desired organoleptic qualities of wines. Hence, in some wine types, the development of Oenococcus oeni, Lentilactobacillus hilgardii, and Pediococcus spp. needs to be prevented. Currently, the primary method to combat microbial wine spoilage is through the addition of sulphites. However, given that global warming limits the effectiveness of sulphites, and that the use of this preservative no longer meets consumer expectations, initiatives are being developed to find alternative methods.
In ENDOWINE, we examined the potential of phage endolysins as antimicrobials in wine. Endolysins are phage-encoded enzymes that degrade the peptidoglycan layer of the host bacterial cells at the end of the lytic phage replication cycle, and they have been shown to be bactericidal upon direct exogenous application to bacterial cells. To date, little research has been conducted on the application of endolysins in food products, but they are already used in medical and veterinary settings, demonstrating their potential. In addition, the structurally and functionally related egg lysozyme is already permitted as a food additive.
ENDOWINE focused first on determining the diversity of endolysins in phages infecting wine LAB through in silico analysis. Next, candidate endolysins were selected, cloned, overexpressed, and purified in order to test their enzymatic activity and determine their antimicrobial spectra. Ultimately, the results of ENDOWINE should lead to an application that allows the use of endolysins to target spoilage bacteria in wine.
