中国稻谷可培养真菌群落组成及多样性

真菌生长导致粮食品质下降及真菌毒素污染,是造成粮食损失的主要原因。我们采用形态学与分子系统发育分析相结合的方法,对中国13个省78份稻谷样品的真菌群落组成及多样性进行研究。结果表明,本次共分离622株真菌,经初步鉴定分属于17属73个物种。南北方因气候条件差异较大,稻谷真菌数量和物种组成都存在很大差异。南方稻谷表面真菌数量（10 ⁴cfu/g）明显高于北方（10 ³cfu/g）。北方收获期的优势种主要属于枝孢属Cladosporium,南方收获期的优势种为黄曲霉Aspergillus flavus、黑曲霉Aspergillus niger和阿姆斯特丹曲霉Aspergillus amstelodami等。进入储藏期后,由于中国仓储管理要求较高,储藏环境相对稳定（aw≤0.75）,耐旱真菌阿姆斯特丹曲霉和多育曲霉Aspergillus proliferans（占比40%以上）成为优势种,这类真菌可作为储藏期粮堆异常的早期预警指示菌。南方收获期感染的黄曲霉和黑曲霉进入储藏期后仍保持优势比例,导致储藏期间毒素污染风险必然增加,因此南方稻谷收储环节均应加强监管。本研究通过分析南北方收获和储藏环节稻谷真菌群落组成差异及产毒真菌的分布规律,以期为中国粮库在稻谷收储环节的真菌毒素防控提供依据。

Community composition and diversity of culturable fungi from the rice grains in China

The growth of fungi leading to degradation of grain quality and mycotoxin contamination is the main cause of grain loss. A combination of morphology and molecular phylogenetic analysis were used to study the composition of fungal communities and fungal diversity in 78 rice samples from 13 provinces in China. A total of 622 strains was isolated and 73 species in 17 genera were preliminarily identified. The obvious differences in climatic conditions between the southern and northern regions of China resulted in significant differences in fungal quantity and fungal composition on the rice grain surface. The quantity of fungi on the rice grains in southern China (10 ⁴cfu/g) is significantly higher than that in northern China (10 ³cfu/g). In northern China, the dominant species in harvest period were mainly species of Cladosporium. In southern China, the dominant species during harvest were Aspergillus flavus, A. niger and A. amstelodami, etc. After entering the storage period, with the high requirements of China’s warehouse management, the storage environment is relatively stable (aw≤0.75), and the xerophilic Aspergillus amstelodami and A. proliferans (accounting for more than 40% of the isolates) become dominant. These fungi can be used as an early warning indicator of abnormal grain piles in the storage period. A. flavus and A. niger infection during harvest in the south still maintain the high infection ratio in grain storage, leading to higher risk of mycotoxin contaminations of rice. Therefore, supervision and management should be strengthened during harvest and storage. The result of this study may provide reference for mycotoxin prevention and control of rice grains in China grain depot.