Phytopathology. 1999 Mar;89(3):254-61. doi: 10.1094/PHYTO.1999.89.3.254.
ABSTRACT Transformants of the biocontrol agent Trichoderma harzianum strain CECT 2413 that overexpressed a 33-kDa chitinase (Chit33) were obtained and characterized. Strain CECT 2413 was cotransformed with the amdS gene and its own chit33 gene under the control of the pki constitutive promoter from T. reesei. Southern blotting indicated that the chit33 gene was integrated ectopically, mostly in tandem. Some transformants showed the same restriction pattern, indicating preferable sites of integration. There was no correlation between the number of integrated copies and the level of expression of the chit33 gene in the transformants. When grown in glucose, the extracellular chitinase activity of the transformants was up to 200-fold greater than that of the wild type, whereas in chitin, the activity of both the transformants and the wild type was similar. Under both conditions, the transformants were more effective in inhibiting the growth of Rhizoctonia solani as compared with the wild type. Similar results were obtained when culture supernatants from the transformants and the wild type were tested against R. solani.
摘要 通过对生防菌哈茨木霉 CECT2413 进行过量表达 33kDa 几丁质酶（Chit33）的转化，得到了转化体并对其进行了特性分析。该菌被同时转化 amdS 基因及其自身的 chit33 基因，这些基因均由里氏木霉的 pki 组成型启动子控制。Southern 印迹分析表明，chit33 基因以串联的方式随机整合到基因组中。一些转化体表现出相同的限制模式，表明存在偏好的整合位点。整合拷贝数的多少与转化体中 chit33 基因的表达水平没有相关性。在葡萄糖中生长时，转化体的胞外几丁质酶活性比野生型高 200 倍，而在几丁质中，转化体和野生型的酶活性相似。在这两种情况下，与野生型相比，转化体对腐霉菌的生长抑制效果更好。用转化体和野生型的培养上清液对腐霉菌进行测试，也得到了类似的结果。
