Pulsed Electric Field Inactivation of Acetobacter aceti: Mechanisms and Efficacy Elucidation

The spoilage bacterium <i>Acetobacter aceti</i> poses a major threat to wine quality by causing acetification, driving the need for effective control methods. This study investigated the inactivation of <i>A. aceti</i> using pulsed electric field (PEF) and elucidated the multi-target mechanisms. The results demonstrated that PEF efficacy was highly dependent on the electric field intensity. PEF treatment at 30 kV/cm achieved a >3-log reduction in viable cell counts, with a Weibull model analysis indicating a critical inactivation threshold of 21.64 kV/cm. Mechanistic investigations revealed that PEF induced irreversible damage to the cell membrane, evidenced by morphological rupture (SEM) and a 4-fold increased permeability (flow cytometry), which led to a massive leakage of intracellular contents. Critically, this physical damage was correlated with profound physiological disruption, including the inactivation of key spoilage enzymes alcohol dehydrogenase (ADH, 80.0% relative activity loss) and aldehyde dehydrogenase (ALDH, 93.1% relative activity loss). Furthermore, PEF induced severe oxidative stress (4.25-fold increase in ROS and 3.30-fold increase in MDA) and a collapse in energy metabolism. Collectively, these findings reveal a synergistic inactivation mechanism, which establishes a strong theoretical foundation for the potential development of PEF as a non-thermal strategy to control acetic spoilage in winemaking.