Insights into the changes in cell wall polysaccharides and ROS metabolism of fresh-cut chili pepper (Capsicum annuum L.) infected by Enterobacter cloacae

Abstract

Enterobacter cloacae, a typical spoilage bacterium, causes severe textural softening of freshly cut chili pepper. This study investigated the mechanisms of E. cloacae-induced textural softening involving cell wall polysaccharide disassembly and reactive oxygen species (ROS) production. It was found that E. cloacae-inoculated samples had lower firmness and greater weight loss than the control group. Meanwhile, E. cloacae inoculation promoted cell wall decomposition; cell wall polysaccharide disassembly, such as cellulose and Na₂CO₃-soluble pectin; and enhanced cell wall-degrading enzyme (CWDE) activity (polygalacturonase, pectin methylase, pectin lyase, β-galactosidase, α-L-arabinofuranosidase, cellulase, and xyloglucan endotransglycosylase). Furthermore, high H₂O₂ content, low GSH content, and reduced activities of superoxide dismutase, catalase, and ascorbate peroxidase were found in the E. cloacae-inoculated group during late storage. Overall, E. cloacae-induced textural softening of fresh-cut chili peppers resulted from cell-wall polysaccharide degradation due to increased CWDE activity, ROS accumulation, and reduced ROS-scavenging capacity.