Analysis and correlation of fungal community structure and moisture indicators of medium-high-temperature and high-temperature Daqu from Northwest Canal region of Shandong Province
摘要
To investigate the quality differences between medium-high- and high-temperature Daqu in the Northwest Canal region of Shandong province, the fungal community structure, and moisture indicators (water content, water activity, bound water, immobile water, and free water content) were analyzed by PacBio SMRT sequencing technique, conventional physicochemical testing methods, and low field-nuclear magnetic resonance (LF-NMR) technology. Additionally, the correlation between dominant fungal species and moisture indicators was analyzed. Sequencing results revealed that Aspergillus proliferans was the dominant species in medium-high-temperature Daqu, with an average relative abundance of 55.08%, whereas Thermomucor lanuginosus predominated in high-temperature Daqu, with an average relative abundance of 34.66%. A total of 12 significantly differential substances were identified by linear discriminant analysis effect size (LEfSe), which showed distinct differences in the two types of Daqu samples. Among them, A. proliferans and T. lanuginosus could serve as biomarkers for medium-high-temperature Daqu and high-temperature Daqu, respectively. Moisture indicators analysis results demonstrated that medium-high-temperature Daqu had significantly higher water content (11.00%), water activity (0.641), immobile water (5.04%), and free water (0.96%) (P<0.05), whereas high-temperature Daqu exhibited significantly higher bound water content (94.96%) (P<0.05). Correlation analysis results showed that there was a significant or extremely significant correlation between the dominant fungal species and the moisture indicators (P<0.05 or P<0.01). These findings provided data support for elucidating the quality variations among different types of Daqu in Northwest Canal region of Shandong province.