Abstract: To explore the production of induced secondary metabolites by a co-culture of Paecilomyces hepiali and actinomycete.A strain of actinomycete TY134 with strong antibacterial activity was isolated from the soil microbial flora of Ophiocordyceps sinensis. This actinomycete was identified as Streptomyces fulvissimus on the basis of 16S rDNA.The monoculture of P.hepiali, actinomycete TY134 respectively,and the co-culture were done on rice solid medium for 30 days,then the fermentation products were extracted by the aid of ultrasonic with ethyl acetate respectively.Comparison of the chemical composition and antimicrobial activity of the ethyl acetate extract of monoculture and co-culture were performed by HPLC and double drilling method respectively.The results showed that the co-culture of ethyl acetate extract produced a new absorption peak at the retention time 14.143 min,and there was no evidence of the absorption peak in monoculture.In addition,the anti-bacterial activity of the ethyl acetate extract of the co-culture was stronger than that of the monoculture,produce chemical components with new anti-microbial activities.All the results indicated that co-culture can be used as a promising approach to discover new bioactive secondary metabolites.

Key words: Paecilomyces hepiali, actinomycete, co-culture, monoculture, secondary metabolites