少根根霉产孢能力、变种与发酵产物的相关性

The correlations of fermentation metabolites with sporulation capability and varieties of Rhizopus arrhizus

【目的】探究少根根霉不同生态环境、不同地理位置、不同产孢能力和不同分类学变种的发酵产物多样性及相关性,为工业生产提供指导。【方法】代表性的68株少根根霉菌株于糯米培养基中进行液态发酵,利用高效液相色谱法测定各种发酵产物浓度,计算发酵产物间的Pearson相关系数,通过多因素方差分析和主成分分析解析各类菌株与发酵特性的相关性。【结果】总计检测到7种发酵产物,按照产量均值百分比从高到低分别是葡萄糖(70.96%)、乙醇(17.87%)、乳酸(6.63%)、麦芽糖(1.80%)、苹果酸(1.46%)、富马酸(0.92%)和甘油(0.36%)。麦芽糖独立代谢,其余6种产物分为2组,组间负相关:第一组为葡萄糖、乳酸和甘油,组内正相关;第二组为乙醇、苹果酸和富马酸,组内正相关。发酵特性与生态环境、地理位置的相关性较低,但与产孢能力、分类学变种高度相关。SM无孢菌株的发酵能力显著强于SM产孢菌株,尤其是菌株XY01957的葡萄糖产量高达138.30g/L,具有出色的生产潜力。原变种和东京变种的富马酸、苹果酸产量较低,而乳酸和甘油产量较高;德氏变种与前两个变种区分明显,富马酸、苹果酸产量较高,而乳酸和甘油产量较低。【结论】本研究发现少根根霉发酵产物之间以及发酵产物和产孢能力、分类学变种之间高度相关,为群体遗传学研究奠定了良好的基础;本研究筛选出优质的发酵菌株,为发酵工业提供了坚实的支撑。

[Objective] In order to provide guidance for industrial production, this study investigated the diversity and correlation of metabolites among Rhizopus arrhizus strains in different ecological habitats, in different geographical locations, with different sporulation capacities, and of different taxonomic varieties. [Methods] Sixty-eight representative strains of R. arrhizus were inoculated in glutinous rice media for liquid fermentation, and the yields of secondary metabolites were determined by high-performance liquid chromatography. Pearson correlation coefficients between fermentation products were calculated. The correlation between strains and fermentation characteristics was assessed by multivariate analysis of variance and principal component analysis. [Results] A total of seven fermentation products were detected, including glucose(average yield in percentage: 70.96%), ethanol(17.87%), lactic acid(6.63%), maltose(1.80%), malic acid(1.46%), fumaric acid(0.92%), and glycerin(0.36%). Maltose was metabolized independently, while the other six were divided into two groups with a negative inter-group correlation. The first group contained glucose, lactic acid, and glycerol, which were positively correlated with each other. The second group included ethanol, malic acid, and fumaric acid, also showing positive correlations. Fermentation characteristics were significantly correlated with sporulation capacities and taxonomic varieties, while slightly with ecological habitats and geographical locations. The strains not producing spores in synthetic mucor liquid medium had significantly stronger fermentation ability of than the SM spore-producing strains. In particular, strain XY01957 had the potential for industrial production since it could produce glucose at a yield as much as 138.30 g/L. The varieties arrhizus and tonkinensis had lower content of fumaric acid and malic acid while higher content of lactic acid and glycerin, whereas delemar was obviously opposite to the two varieties above with respect to all these components. [Conclusion] This study demonstrated high correlations among fermentation metabolites, sporulation capacities, and taxonomic varieties of R. arrhizus, laying a sound foundation for population genetic research. Some high-quality strains were screened out, providing solid support for the fermentation industry.