制麦过程优势真菌分离鉴定及其群落结构和多样性分析

Isolation and identification of dominant fungi and diversity analysis of its community structure during malting

采用高通量测序技术结合分离培养的方法研究了制麦过程中真菌群落结构及其多样性,并利用平板透明圈法考察不同真菌产胞外淀粉酶、蛋白酶、纤维素酶和木聚糖酶的能力。形态学及ITS-rRNA序列结果表明,来自6个制麦阶段样品中的真菌属于2门、6纲、15属、25种。高通量测序结果表明,样本中真菌物种丰富度在浸麦结束时最低,在排潮结束时最高。在6个制麦阶段样品中共检测到2真菌门、58真菌属。担子菌门是浸麦和发芽前期的优势门,子囊菌门是发芽结束至成品麦芽中的优势门。属水平上,未分类的酵母菌目、链格孢属和线黑粉酵母属等13个真菌属为制麦过程中的优势属,不同制麦阶段的标志性真菌属存在差异。胞外酶筛选试验结果表明,制麦过程中的真菌群落对麦芽水解酶系有一定的贡献,且接种产胞外酶活性较高的真菌可提升麦芽的浸出率和糖化力。该研究将为工业制麦的品质调控与工艺优化提供理论依据。

High-throughput sequencing combined with isolation and culture methods were used to explore the fungal community structure and diversity during malting,the ability of different fungi to produce extracellular amylase,protease,cellulase,and xylanase was also investigated with the plate transparent circle method.The results of morphology and ITS-rRNA sequencing showed that the fungi in samples from the 6 malting stages belonged to 2 phyla,6 classes,15 genera,and 25 species.The results of high-throughput sequencing showed that the fungal species richness was the lowest at the end of steeping and the highest at the end of withering.Two fungal phyla and 58 fungal genera were detected in the samples from 6 malting stage Basidiomycota was the dominant phylum for the samples from steeping and pre-germination,while Ascomycota was the dominant one for those from the end of germination and the malt products.At genus level,13 fungus genera,including unclassified_o_Saccharomycetales,Filobasidium,and Alternaria,were the dominant ones in malting;the marked fungus genera varied with different malting stages.Screening on extracellular enzyme suggested the fungal community in malting presented certain contribution to the malt hydrolase.Malt extract and diastatic power were improved when the fungi with the ability to produce more extracellular enzymes were introduced to malting.This study would provide theoretical basis for quality control and process optimization of industrial malting.