少根根霉多样化的生长动力学模型

Diversity of growth kinetic models for Rhizopus arrhizus

【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。

[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.Lo wer 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.