Lysogeny in the Lactic Acid Bacterium Oenococcus oeni Is Responsible for Modified Colony Morphology on Red Grape Juice Agar

The presence of white and red colonies on red grape juice (RGJ) agar during enumeration of Oenococcus oeni in wine samples is frequently observed by stakeholders in the wine industry. Our study brings an explanation for this intriguing phenomenon and establishes a link between the white-red color switch and the lysogenic state of O. oeni . It also provides a simple and inexpensive method to distinguish between lysogenic and nonlysogenic derivatives in O. oeni with a minimum of expended time and effort. Noteworthy, the protocol could be adapted to two other species of LAB, namely, Leuconostoc citreum and Lactobacillus plantarum . It could be an effective tool to provide genetic, ecological, and functional insights into lysogeny and aid in improving biotechnological processes involving members of the lactic acid bacterium (LAB) family.