番红花链格孢菌的分离及其生物学特性研究

Studies on Biological Characteristics of Alternaria alternata obtained from the corms of Crocus sativus L

从番红花球茎中分离到一种新的内生真菌，经形态学和生长特性等研究初步鉴定其为半知菌类链格孢属链格孢Alternaria alternata（Fr．：Fr．）Keissler．该菌能单独引起番红花球茎腐烂，与青霉菌互作时腐烂程度加重．环境和营养因子时该菌的生长繁殖影响较大：①在10～35℃时，茼丝能生长并形成孢子．最适生长繁殖温度为28℃，孢子的致死温度为65℃；②在pH为4．0～7．0时，菌丝生长、孢子形成和萌发均良好，最适pH值为6．0；③当空气相对湿度（RH）高于80％时，菌丝才能生长并形成孢子．RH高于85％，孢子才能萌发；④能直接利用葡萄糖和蔗糖，淀粉和甘油需分解后才能被良好利用；⑤氮源以有机态氮和硝态氮为佳，铵态氮对其生长繁殖有抑制作用．

A new kind of endogenetic fungus, found in the corms of Crocus sativus L. , was identified to be Alternaria alternata （Fr. ： Fr. ） Keissler based on its morphological and biological characteristics. The fungus would cause the corm rotten under certain conditions, and the symptom would be more serious when it incorporates with penicillium. The effect of environmental and nutritional factors on its growth and reproduction was remarkable. i） The temperature from 10 to 35℃ were is suitable for mycelial growth, sporogenesis and spore germination. However, the optimum temperature is 28℃. For spores, the lethal temperature is 65℃ lasting 10 minutes, ii） When pH ranges 4.0-7.0 in the media, it is favourable for mycelial growth, sporogenesis and spore germination. However, the optimum pH was 6.0. iii） The relative humidity must be higher than 80% for mycelial growth and sporogenesis, and the lowest RH for spore germination is 85%. iv） The best as to carbon sources for mycelial growth and sporogenesis are glucose or saccharose, while starch or glycerin can not be diretly used, unless they were decomposed previously. v） As to nitrogen sources, the fungus could utilize NO3^--N （nitrate） very well, while NH4^＋-N （ammonium） inhibit its growth and sporogenesis.