The Fruit Biome: Biofilm Dynamics and Consumer Health Risks with Focus on the Apple (Malus domestica) as a Model System

Fruit surfaces serve as ecological interfaces that support diverse microbial communities, where biofilm formation by spoilage organisms and human pathogens contributes to postharvest safety concerns. Although fruit-associated microbiota and chemical residues have been widely investigated, the interactions between surface microstructure, residue dynamics, and microbial persistence remain insufficiently integrated. This review synthesizes current knowledge by considering three key processes: temporal succession of microbial communities, structural vulnerability of the fruit surface, and chemically mediated selective pressures. Using apple (Malus domestica) as a model system, we examine how structural features such as lenticels and cuticular microdamage interact with pesticide residues to facilitate microbial retention, sequestration, and internalization. Evidence indicates that pesticide residues may act as selective stressors and, in some cases, potential metabolic substrates, thereby enhancing microbial persistence and tolerance to sanitization. These combined factors contribute to the formation of a high-persistence surface environment. Integrating microbiological, chemical, and plant structural perspectives, this review provides a mechanistic basis for the limited effectiveness of conventional decontamination approaches and highlights the need for multidisciplinary postharvest strategies to improve produce safety and shelf life.