{'fraction_non_alphanumeric': 0.020844189682126108, 'fraction_numerical': 0.006774361646690985, 'mean_word_length': 6.084870848708487, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Geography‐ and Host Physiology‐dependent Variations in Leaf‐associated Bacterial Community of Field‐grown Broccoli

Most of the studies about fresh produce‐associated microbiota have paid attention to pathogenic bacteria causing foodborne illness. Recent studies revealed that fresh produces harbor diverse bacterial populations on their surfaces; however, little is known about community structure and diversity of bacterial populations on fresh produces and how they changes dependent on geography, host physiology and meteorology. Here, we analyzed leaf surface‐associated bacterial communities of 66 field‐grown broccolis collected from 22 commercial farms widely distributed in the whole Jeju Island using 454 pyrosequencing of 16S rRNA gene amplicons. Total number of bacteria averaged 3.8±2.0 CFUs per gram of broccoli tissue. The composition and diversity of bacterial community varied the most on sampling field, followed by growth stage and physiological status. The most abundant phyla were Proteobacteria, followed by Actinobacteria, Firmicutes and Bacteroidetes. Of them, five OTUs assigned into Pseudomonas, Acinetobacter, Oxalobacteraceae, Comamonadaceae and Enterobacteriaceae were commonly found in more than a half of samples, suggesting that they form core members of leaf‐associated microbiota on broccoli. Site‐specificity of bacterial communities was associated significantly with relative humidity and precipitation, followed by cloudy; but, not with temperature. In comparison with other types of fresh produces, bacterial community of broccoli was more similar to those of fresh vegetables close to soil than tree fruits and vegetables, indicating that exposure to soil could be critical for the development of bacterial populations on fresh produces. This study offers new knowledge on variability of leaf‐associated bacterial populations of fresh produces depending on environment conditions.