Postharvest processing decreases the richness of bacterial taxa in the phyllosphere of broccoli

Abstract

Diverse bacterial communities residing on the surfaces of fresh vegetables are important for food quality and safety; however, knowledge of the phyllosphere microbiota on fresh vegetables and of how it changes during postharvest stage is poorly understood. We used culturing to quantify bacterial abundance and 16S rRNA 454 pyrosequencing to analyse the bacterial community composition on broccoli florets collected from farms (preharvest) and retail stores (postharvest). The bacterial community compositions of the preharvest and postharvest broccoli were significantly different. The number of non-Escherichia coli coliform bacteria (Hafnia sp. and Rahnella sp.) was higher in the postharvest broccoli than in the preharvest broccoli. Minor bacterial taxa at the phylum and genus levels had markedly disappeared in the postharvest broccoli, resulting in low bacterial species richness in the postharvest broccoli. The dominant bacterial taxa persist and prevail in the phyllosphere of broccoli during the postharvest stage. A popular crop of leafy vegetables, broccoli, is of great agricultural and nutritional importance. This study provides a detailed description of changes in the bacterial community of broccoli in harvest and storage. This study presents novel data on the impact of postharvest conditions on the bacterial populations on broccoli florets.