少根根霉多样化的生长动力学模型

【背景】少根根霉物种内菌株间生理生化指标存在差异,相应的遗传背景不明,不利于少根根霉生产发酵的进一步应用。【目的】探究不同少根根霉菌株温度-生长动力学模型间的差异,为其群体遗传研究奠定基础,为生产菌株的筛选提供依据。【方法】选取来自欧亚各地的纯种少根根霉为实验材料,通过形态学鉴定,以及ITS和IGSrDNA分子系统发育重建进行分子鉴定,采用培养基平板培养直接测量法进行温度-生长动力学分析。【结果】少根根霉温度-生长动力学模型呈现丰富的多样性,与各形态和分子系统发育变种基本不具有相关性。菌株间温度-生长速度曲线具有显著性差异。少根根霉生长抑制低温范围、最适生长温度范围、生长抑制高温范围和致死高温范围分别为4-9、30-37、40-49和40-52°C。菌株XY00454和XY00469具有良好的高温适应性和较快的生长速度,有开发成为工业发酵菌的潜力。【结论】少根根霉物种仍然处于剧烈的演化之中,种内形态、分子和生理分化较为活跃,但尚未形成任何独立的种群。根据温度适应性的数据可以筛选出发酵生产潜力菌株。

Diversity of growth kinetic models for Rhizopus arrhizus

[Background] Strains of Rhizopus arrhizus vary in physiological and biochemical indicators, but relative genetic background is unclear, hindering their further applications in fermentation. [Objective] This study explored temperature-growth kinetic models among strains of R. arrhizus in order to lay a foundation for investigating population genetics and for screening materials potential in production. [Methods] R. arrhizus isolated from Asia and Europe were first identified by morphology and then by molecular phylogeny reconstructed with ITS and IGS rDNA. Finally, their temperature-growth kinetics was analyzed by directly measuring colonial diameters on medium plates. [Results] The temperature-growth kinetic models of R. arrhizus were diverse, and the curves significantly differ, with less relatedness to morphological and phylogenetic varieties. Lower restraining growth, optimum growth, higher restraining growth, and fatal temperatures were 4?9, 30?37, 40?49, and 40?52 °C, respectively. Strains XY00454 and XY00469 grew rapidly and adapted well to higher temperatures and therefore were potential for industrial production. [Conclusion] R. arrhizus is still evolving violently and diverging actively in morphology, molecular and physiology, while not developing any independent populations. It is feasible to screen fermentation potential isolates based on thermal adaptability.