丝状真菌Sr18发酵过程中的形态学研究

Study on the Morphology of Filamentous fungus Sr18 in Submerged Fermentation

通过扫描电镜对Sr18菌发酵过程中茵丝生长的形态进行观察,结果表明:在适宜的摇瓶培养条件下所形成的菌球直径多在1．5—2．0 mm,内、外部菌丝较丰满,粗细均一,内部无明显空洞,菌体生理活性较强,其发酵滤液稀释为原浓度1／2的杀线虫活性可达90％以上; 减少接种量或改变培养基配方多形成直径为4～5 mm的空心大菌球,内层出现较明显空洞及大量干瘪菌丝,中间层含大量分生孢子头和孢子,代谢物的杀虫活性降到77．17％～25％; 加大接种量降低转速则易形成直径小于1 mm实心致密菌球,菌丝粗细不均匀,杀虫活性仅为67．5％。5 L发酵罐发酵则多形成松散的菌丝团,菌丝丰满,粗壮,菌体生理活性状态良好, 积累代谢产物能力强,杀虫活性为95％以上。

The morphology of filamentous fungus Sr18 was studied in the process of submerged fermentation by scanning electron microscope（SEM）. The result showed that the nematicidal activity of metabolites related closely to the morphology of Sr18 hyphae. The pellets were formed during submerged fermentation of Sr18 in conical flask and the size of the pellets, which had direct influence on the activity of the metabolites, varied with medium components and culture conditions. The pellets were quite different when the conidial concentration or medium component were changed. Under optium fermentation conditions, a round, hard, cream-colored pellet was usually formed with 1.5 2.0 mm diameter for high yield of nematicidal metabolites which activity was about 95%. The diameter of pellets was most 4 - 5 mm, and with large quantity of spore heads and spores when the concentration of conidiospores reduced or the medium components changed, and its nematicidal activity declined to 77.15% - 25%. Compact pelltes which diameter were less than 1 mm were formed when increased the inoculation spores or decreased the rotate speed. And its nematicidal activity was only 67.5%. Filamentary-like hyphae was formed in 5L fermenter with a high level of nematicidal metabolite production.