摘要
目的:从海洋底泥样品中筛选能低温降解果胶的新颖菌株,发掘具有潜在产业化价值的果胶酶.方法:以果胶为唯一碳源,利用透明圈法和 3,5-二硝基水杨酸法(DNS法)从大连渤海湾海泥中筛出一株高产果胶酶菌株.对其进行形态学、生理生化特征分析以及 16S rDNA序列测定,BLAST同源基因比对后构建系统发育树,并进一步研究其酶学特性.结果:筛选高产果胶酶菌株命名为LY-1,通过 16S rDNA序列分析并结合生理生化鉴定确定该菌株为橄榄灰链霉菌(Streptomyces olivogriseus).菌株LY-1在 25℃、180 r/min的条件下培养至 24h时,果胶酶的酶活力为 30.56 U/mL.最适酶pH为 8.0,最适酶温度为 20℃.此外,该酶在 60℃孵育 2h仍保持70%以上的酶活性,在 pH7.0～9.0范围内稳定性良好,酶活性稳定维持在 90%以上.金属离子 Cu2+、Ba2+、Mg2+、Ca2+、K+、Co2+促进该酶活性,Mn2+、Zn2+、Hg2+、Na+则抑制该酶活性.结论:菌株LY-1所产的果胶酶具有应用于产业化商用果胶酶的潜力.
Abstract
Objective:To select novel strains that could degrade pectin at low temperature from marine sediment samples and discover pectinase with potential industrial value.Methods:Take pectin as the only carbon source,screening a high-yielding pectinase strain from sea mud in Bohai Bay,Dalian with the transparent circle method and the 3,5-dinitrosalicylic acid method(DNS method).It analyzed the morphological,physiological and biochemical characteristics,and determined the 16S rDNA sequence.After comparing BLAST homologous gene,it built up a phylogenetic tree,and further studied the enzymatic properties.Results:It screened the strain with high pectinase yield which was named LY-1.Then it analyzed the 16S rDNA sequence and determined that this strain was Streptomyces olivogriseus from the physiological and biochemical index.When strain LY-1 was cultured at 25℃and 180 r/min for 24 hours,the enzyme activity of pectinase was 30.56 U/mL.It showed that the optimal enzyme pH was 8.0,and the optimal enzyme temperature was 20℃.Furthermore,the enzymatic activity could still be maintained more than 70%when it was incubated at 60℃for 2 hours,and remained stable in the pH range of 7.0～9.0 with enzyme activity at over 90%.The metal ions Cu2+,Ba2+,Mg2+,Ca2+,K+,and Co2+ could promote the activity of this enzyme,while Mn2+,Zn2+,Hg2+,and Na+ would inhibit its activity.Conclusion:The pectinase produced by strain LY-1 would have the potential to be applied to industrial commercial pectinase.
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