Graeme-Cook K A, Faull J L
Department of Biology, Birkbeck College, London, United Kingdom.
Can J Microbiol. 1991 Sep;37(9):659-64. doi: 10.1139/m91-112.
Mutants of Trichoderma harzianum with altered antibiotic production were isolated using ultraviolet light mutagenesis. These included strains whose activity in a Fusarium oxysporum spore germination assay was greater than twice that of the parental strain and one that had no detectable antifungal activity. Characterisation of extracellular metabolites of these strains using thin-layer chromatography and gas-liquid chromatography showed that the strains with high activity produced only elevated levels of a 6-n-pentyl pyrone, the antibiotic produced by the parental strain, but two new antifungal compounds. One of these has been identified as an isonitrile antibiotic. The nature of the interactions of the mutants with Fusarium oxysporum, Rhizoctonia solani, and Pythium ultimum was examined in an in vitro dual-plating assay using two media. High antibiotic production by two T. harzianum strains, BC10 and BC63, did increase inhibition of hyphal growth of R. solani and P. ultimum, but there was no correlation between increased antibiotic production and colonisation ability. In some cases the increased antibiotic levels appeared to impede colonisation of F. oxysporum and R. solani by the mutants. Slow growth rate also affected colonising ability. The types of interactions showed great variability depending on the nature of the T. harzianum isolate and on the test fungus.
利用紫外线诱变分离出了哈茨木霉抗生素产量发生改变的突变体。这些突变体包括在尖孢镰刀菌孢子萌发试验中活性比亲本菌株高两倍以上的菌株，以及一株未检测到抗真菌活性的菌株。使用薄层色谱法和气液色谱法对这些菌株的细胞外代谢产物进行表征，结果表明，活性高的菌株仅产生了亲本菌株所产抗生素6 -正戊基吡喃酮的水平升高，但还有两种新的抗真菌化合物。其中一种已被鉴定为异腈类抗生素。在使用两种培养基的体外双平板试验中，研究了这些突变体与尖孢镰刀菌、立枯丝核菌和终极腐霉之间相互作用的性质。两株哈茨木霉菌株BC10和BC63的高抗生素产量确实增加了对立枯丝核菌和终极腐霉菌丝生长的抑制作用，但抗生素产量的增加与定殖能力之间没有相关性。在某些情况下，抗生素水平的增加似乎阻碍了突变体对尖孢镰刀菌和立枯丝核菌的定殖。生长速率缓慢也会影响定殖能力。相互作用的类型因哈茨木霉分离株的性质和测试真菌的不同而表现出很大的变异性。
