1.1 Test strains
The D. flagrans isolate used in this study was F088 (CGMCC No. 11209), the gene database entry number is KU881774.1, which was isolated and purified from sheep feces collected in Heilongjiang Province, China in 2014 by an improved spreading separation technique. The isolate was stored in refrigerator at 4 ℃ on test tube containing 2% cornmeal agar. Mycelium and spores were taken from the preserved inclined plane and inoculated on Potato Dextrose Agar (PDA, Beijing Landbridge Technology Co., LTD.) plate containing chloramphenicol and incubated at 28 ℃ for 7 days.