Antimicrobial mechanism of green citrus peel extract against Gluconobacter cerinus causing decay in 'Xuxiang' kiwifruit.

Abstract

Kiwifruit is highly vulnerable to microbial infection and subsequent decay during the postharvest stage, leading to significant economic losses in the kiwifruit industry. In this study, a Gluconobacter cerinus strain was isolated from decayed 'Xuxiang' kiwifruit and confirmed to rapidly induce fruit decay through inoculation tests. The antibacterial activity of green citrus peel extract (GCPE) against G. cerinus CX2 and its effects on kiwifruit preservation during storage were further investigated. The results showed that GCPE exhibited strong antibacterial activity, with a minimum inhibitory concentration (MIC) of 2.5 mg/mL and a minimum bactericidal concentration (MBC) of 5 mg/mL, and induced leakage of ATP and macromolecules. Live/dead cell staining and scanning electron microscopy revealed that GCPE disrupted the integrity of the cell membrane and cell wall of G. cerinus CX2, respectively. Furthermore, treatment of kiwifruit inoculated with G. cerinus CX2 with GCPE effectively delayed fruit decay. These findings indicate that GCPE possesses significant potential to suppress the growth of G. cerinus CX2, a pathogen responsible for kiwifruit decay, and could be developed as a novel bio-preservative to control kiwifruit rot caused by this pathogen.