| 摘要: |
| 【目的】探索苹果树腐烂病菌致病力与胞外果胶酶的关系，筛选最佳产酶的碳、氮源，为揭示该病菌致病机理提供依据。【方法】用MS培养基培养苹果树腐烂病菌野生型菌株03-8及其2个突变体(致病力增强突变体X907，致病力丧失突变体T1)菌株，于5，10，15和20 d取样，用3,5-二硝基水杨酸(DNS)比色法测定其培养滤液中果胶酶的活性，探讨致病力与酶活性的关系。以野生型菌株03-8为供试菌株，改变MS培养基中的碳(葡萄糖、麦芽糖、根皮苷、果胶、可溶性淀粉)、氮(硫酸铵、牛肉膏、蛋白胨、酵母膏、L-天门冬酰胺)源培养03-8菌株，于5，10，15和20 d取样，分别测定各培养滤液中果胶酶的活性，确定最佳碳氮源。用不同含量的最佳碳、氮源与MS培养基培养03-8菌株，10 d时取样，测定胞外果胶酶活性，确定培养基中最佳碳、氮源的含量。【结果】在MS培养基中发酵10 d，苹果树腐烂病菌致病力增强突变体(X907)产生的胞外果胶酶活性最高，致病力丧失突变体(T1)产生的酶活性最低。用可溶性淀粉、果胶为碳源培养野生型菌株03-8，在第10天培养滤液中果胶酶活性均高于其他供试碳源；以可溶性淀粉为碳源，其含量为0.5%时培养滤液中果胶酶活性最高。在5种供试氮源中，以0.25%蛋白胨为氮源发酵10 d产生的胞外果胶酶活性最高。【结论】3种苹果树腐烂病菌发酵10 d产生的胞外果胶酶的活性与其致病力相关；含0.50%可溶性淀粉和0.25%蛋白胨的MS培养基为苹果树腐烂病菌产酶的最佳培养基，发酵10 d培养滤液中果胶酶的活性最高。 |
| 关键词: 苹果树腐烂病菌 胞外果胶酶 碳源 氮源 |
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| 基金项目:高等学校博士学科点专项科研基金项目(20120204110002)；国家自然科学基金项目(31171796)；公益性行业(农业）科研专项(201203034)；陕西省科技统筹创新工程计划项目(2011KTZB02-02-02) |
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| Effects of different carbon and nitrogen sources on activity of extracellular pectinase of Valsa mali var.mali |
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HE Yuan-yuan,YU Zhe,WANG Hai-ying,et al
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| Abstract: |
| 【Objective】This study explored the relationship between the pathogenicity of Valsa mali var.mali and extracellular pectinase,aiming to screen the optimal carbon and nitrogen sources for enzyme production and to provide a theoretical basis for revealing the pathogenic mechanism.【Method】Wild type Valsa mali var.mali (03-8) and its mutants (a high pathogenic mutant X907 and a non pathogenic mutant T1) were cultured for 5,10,15 and 20 days in MS medium.The activity of pectinase in fermentation liquid was detected using the 3,5-dinitrosalicylic acid (DNS) colorimetric method,and the relationship between pathogenicity and pectinase activity was discussed.Moreover,optimal carbon sources (glucose,maltose,phlorizin,pepctin,and soluble starch) and nitrogen sources (ammonium sulphate,beef extract,peptone,yeast extract,and L-asparagine) for pectinase production of wild type strain 03-8 were screened after measuring the activity of pectinase in samples collected at 5,10,15 and 20 d.The wild type strain 03-8 was cultured for 10 days in MS medium containing different content of carbon and nitrogen sources, then the activity of extracellular pectinase was measured in order to get the optimal carbon and nitrogen sources.【Result】When Valsa mali var.mali was cultured for 10 days in MS media,the high-pathogenic mutant (X907) had the highest pectinase activity,while the non-pathogenic mutant (T1) had the lowest activity.Soluble starch and pectin were more suitable for enzyme production among the tested carbon sources and the optimal content of starch was 0.50%.Similarly,among the five nitrogen sources,peptone with a concentration of 0.25% was the optimum.【Conclusion】The activity of pectinase produced by the three kinds of Valsa mali var.mali had effects on the pathogenicity when being cultured for 10 days.MS medium with 0.50% starch and 0.25% peptone was the optimal medium.Moreover,pectinase showed the highest activity after being cultured for 10 days. |
| Key words: Valsa mali var.mali extracellular pectinase carbon source nitrogen source |
