Lima Luzia H. C., Ulhoa Cirano J., Fernandes Adrienne P., Felix Carlos R.
Empresa Basileira de Pesquisa Agropecuária (EMBRAPA/CENARGEN), 70849-000, Brasilia, DF, Brasil.
J Gen Appl Microbiol. 1997 Feb;43(1):31-37. doi: 10.2323/jgam.43.31.
Trichoderma harzianum is an effective biocontrol agent of several important plant pathogenic fungi. This Trichoderma species attacks other fungi by secreting lytic enzymes, including beta-1,3-glucanase and chitinolytic enzymes. Superior biocontrol potential may then be found in strains having a high capacity to produce these enzymes. We have therefore evaluated the capacity of six unidentified Trichoderma spp. isolates to produce chitinolytic enzymes and beta-1,3-glucanases in comparison with T. harzianum 39.1. All six isolates demonstrated substantial enzyme activity. However, while the isolates hereafter called T2, T3, T5, and T7 produced lower amounts of enzymes, the activity of isolates T4 and T6 were 2-3 fold higher than that produced by T. harzianum 39.1. A chitinase produced by the T6 isolate was purified by a single ion-exchange chromatography step and had a molecular mass of 46 kDa. The N-terminal amino-acid sequence showed very high homology with other fungal chitinases. Its true chitinase activity was demonstrated by its action on chitin and the failure to hydrolyze laminarin and p-nitrophenyl-beta-N-acetylglucosaminide. The hydrolytic action of the purified chitinase on the cell wall of Sclerotium rolfsii was convincingly shown by electron microscopy studies. However, the purified enzyme had no effect on the cell wall of Rhizoctonia solani.
哈茨木霉是几种重要植物病原真菌的有效生物防治剂。这种木霉属物种通过分泌包括β-1,3-葡聚糖酶和几丁质分解酶在内的裂解酶来攻击其他真菌。因此，在具有高能力产生这些酶的菌株中可能发现更高的生物防治潜力。我们因此评估了六种未鉴定的木霉属物种分离株与哈茨木霉39.1相比产生几丁质分解酶和β-1,3-葡聚糖酶的能力。所有六种分离株都表现出大量的酶活性。然而，虽然以下称为T2、T3、T5和T7的分离株产生的酶量较低，但分离株T4和T6的活性比哈茨木霉39.1产生的活性高2至3倍。通过单步离子交换色谱法纯化了由T6分离株产生的一种几丁质酶，其分子量为46 kDa。N端氨基酸序列与其他真菌几丁质酶显示出非常高的同源性。通过其对几丁质的作用以及未能水解海带多糖和对硝基苯基-β-N-乙酰氨基葡糖苷证明了其真正的几丁质酶活性。电子显微镜研究令人信服地表明了纯化的几丁质酶对齐整小核菌细胞壁的水解作用。然而，纯化的酶对立枯丝核菌的细胞壁没有影响。
