Analysis of Microbial Community Structure in Different Rotting Regions of Wax Apple

Abstract

With the rapid development of the tropical fruit industry, wax apple (Syzygium samarangense) has emerged as an economically important crop in southern China due to its distinctive flavor and high nutritional value. However, systematic investigations into microbial community dynamics during its spoilage remain scarce. In this study, high-throughput sequencing was employed to analyze microbial community structures in wax apples at three distinct decay stages. Results demonstrated that bacterial alpha-diversity significantly increased in decayed tissues while fungal diversity declined, with both showing reduced diversity in later stages—a microbial succession pattern analogous to those observed in grapes and blueberries. Notably, fungi likely dominate spoilage initiation by adapting to the host microenvironment through activation of glyoxylate cycle, toxin biosynthesis, and antioxidant defense pathways, mirroring the pathogenesis of Botrytis cinerea. Conversely, bacteria accelerated decay progression by upregulating virulence-associated pathways such as membrane transport and xenobiotic degradation. Bacterial-derived pectinase/cellulase decomposed cell walls to release monosaccharides as fungal carbon sources, while fungal metabolites reciprocally sustained bacterial growth, suggesting a potential synergistic cross-kingdom interaction network. Healthy tissues maintained microbial homeostasis through basal metabolism and antimicrobial compound biosynthesis, exhibiting 1.7-fold higher energy metabolism pathway activity compared to decayed tissues. This study pioneers the characterization of fungal-bacterial dynamics in wax apple spoilage, predicts disease-resistant mechanisms in healthy fruits, and provides theoretical insights for developing targeted antimicrobial preservation strategies.