海南粗榧内生真菌对罗非鱼无乳链球菌抑菌活性研究

利用活菌菌饼法和滤纸片法研究筛选64株海南粗榧内生真菌对罗非鱼源无乳链球菌的抑菌活性，并对活性菌株的代谢产物化学成分进行初步测试。菌饼试验结果显示，11株海南粗榧内生真菌对无乳链球菌具有明显抑制作用，占总菌株数的17.2％，抑菌圈在Φ(8.7±0.3～16.2±0.2)mm间。滤纸片试验结果显示，12株具有明显抑制作用，占总菌数的18.8％，抑菌圈在Φ（8.7±0.3～28.2±0.4）mm间。2种方法的最高活性菌株不一致，但最高活性菌株（B30、F52）和同时显示较高活性的菌株（B14、B30、B32、F7、F52）被测出都含有甾体及三萜类化合物。根据结果推测，对无乳链球菌有显著抑制作用的菌株可能含有甾体及三萜类物质。结果为深入研究内生真菌对罗非鱼无乳链球菌的抑制奠定基础，也为生物防治罗非鱼病害提供有益借鉴。

Antimicrobial Activity of Endophytic Fungi from Cephalotaxus hainanensis Li to Streptococcus agalactiae Isolated from Tilapia

Fungal cake and filter paper methods were used to determine the antimicrobial activity of 64 endophytic fungi from C. hainanensis Li to S. agalactiae isolated from tilapia, and the chemical composition of the active strains was also detected. The results showed that: by the fungal cake method, eleven of 64 strains had significant inhibiting effect on S. agalactiae, 17.2% of the total number of strains, and the inhibition zone diameter ranged from(8.7±0.3)mm to(16.2±0.2)mm. By the filter paper method, there were 12 strains showing significant inhibiting effect on S. agalactiae, which accounting for 18.8% of the total number of the strains. The inhibition zone diameter ranged from(8.7±0.3)mm to(28.2±0.4)mm. The highest activity strain tested by the fungal cake method was not the same with that of the filter paper method. However, the strains of the highest activity(B30 and F52)and the strains of higher activity(B14, B30, B32, F7), which obtained by fungal cake and filter paper methods, were inclusive of steroids and triterpenoids. This paper laid the foundation for further research on the endophytic fungal inhibity activity on S. agalactiae, and also provided a useful reference to the biological control of tilapia disease.