Temporal and spatial variation of bacterial and fungal communities in rice grains during depot storage

Abstract

Microbial activity in stored rice grains may induce quality deterioration and mycotoxin accumulation, resulting in significant economic losses and food safety risks. However, few studies have investigated the migration of microbial communities with storage time and space in stored rice grains. The aim of this study was to understand the assembly and changes of bacterial and fungal communities in rice grains during storage stages. A total of 108 rice samples were collected from 6 different depots, 2 storage times (1-year and 2-year), 3 vertical depths, and 3 horizontal positions during storage periods, and 16 S rRNA and ITS high-throughput sequencing analysis were performed. The main factors influencing the alpha diversity of bacteria and fungi in stored rice grains were grain depot and storage time. A total of 270 bacterial genera and 173 fungal genera were detected in all samples. The most dominant fungi species in all stored rice grains sample were Candida tropicalis (53.24%), Tilletia barclayana (6.19%), Aspergillus heterocaryoticus (4.71%), Fusarium fujikuroi (4.46%). The relative abundance of Fusarium significantly decreased with the storage time increasing, while that of Rhizopus significantly increased. Collectively, this study will improve knowledge regarding microbial communities in rice grains during storage.