The viable but non-culturable state of wine micro-organisms during storage

Colony counting and DEFT did not give the same results when wine micro-orga nisms were enumerated. Both methods were used to monitor the population of acetic acid bacteria (AAB) and lactic acid bacteria (LAB) during wine stora ge. Results suggest that part of the populations had reached a viable but n on-culturable (VBNC) state. These cells were unable to produce colonies but could hydrolyse fluorescent esters and could be counted by DEFT. For AAB, O-2 deprivation quickly induced this stare. Recovery from this state was ve ry rapid as soon as O-2 was available. The response was not so clear for LA B during wine storage. However, a similar state was induced by sulfiting. M oreover, filtration of wine stored in barrels and contaminated by Brettanom yces, AAB and LAB demonstrated that cell size nas not homogeneous. Cells wh ich remained in wine after several weeks could pass through a 0.45-mu m mem brane. However, when they re-entered a growing phase, they were again retai ned by membrane filtration. During and after the decline phase, wine micro- organisms might survive as smaller cells in a VBNC state.