Abstract: The antimicrobial spectrum and the stability of fermentation broth produced by antagonistic strain against Dothiorela gregaria were analyzed， which could be a certain theoretical basis for separation and purification of the bacteriostatic components from the fermentation broth. The effects of ZJNU8990 fermentation broth on seven plant pathogenic fungi were tested by plate standopposite culture method or cylinder plate method. The results indicated that it had the better antagonism on Alternaria solani and Gibberella zeae， and had a certain antagonism on Fusarium oxysporium， Rhizoctonia solani and G. zeae， but had no antagonism on Xanthomonas oryzae pv. Oryzae nor F. oxysporium. Dothiorela gregaria was used as the indicator bacteria， and the thermal stability， pH stability and light stability of fermentation broth was determined using cylinder plate method. The bacteriostatic activity of fermentation broth of antagonistic strain is stable below 90℃， but it complete loss under 121℃. The bacteriostatic activity decreased slightly with pH decrease under acid condition， and decrease significantly with the pH increases under alkaline condition. In addition， it also decreased slightly under UV light and natural light. So the fermentation broth of antagonistic strain had certain development value and application prospect．

Key words: Dothiorela gregaria, antagonistic strain, antimicrobial spectrum, stability