Inhibitory Activity of Metabolites of Endophytic Fungi DBR-12 and DBR-23 from Stephania kwangsiensis Lo.

LIU Xiaoying; SUN Wenbin; CHEN Jieping; QING Zhen; ZHOU Qiuyan; DENG Yecheng

doi:10.15933/j.cnki.1004-3268.2017.03.015

Abstract：The antimicrobial activity of two endophytic fungi DBR-12 and DBR-23 from tuberous root of Stephania kwangsiensis Lo.was determined in order to provide a basis for their utilization in the field of antimicrobial agent.The endophytic fungi were cultivated in liquid medium to produce metabolites,which were then preliminarily isolated by two-phase solvent liquid liquid extraction method,and the antimicrobial activity of metabolites on 10 plant pathogenic fungi and 15 animal pathogens was measured using mycelial growth rate and poison plate methods.The results showed that acetyl acetate extracts from the fermentation products of endophytic fungi DBR-12 and DBR-23 had high antifungal activity against plant pathogenic fungi.The median effective concentration(EC50) values of DBR-12 to 6 plant pathogenic fungi including Bipolaris maydis and so on were 0.010 4-0.079 7 g/L,with the highest activity against Exserohilum turcicum;the EC50 values of DBR-23 to the 10 plant pathogenic fungi except for Bipolaris maydis were 0.020 6-0.174 6 g/L,with the highest activity against Ceratocystis paradoxa.The n-butyl alcohol extract from DBR-12 fermentation product also exhibited high antifungal activity against 5 plant pathogenic fungi including Exserohilum turcicum and so on,and the EC50 values were 0.107 8-0.646 9 g/L,with the highest activity against Diaporthe citri.The minimum inhibitory concentration(MIC) values of acetyl acetate extract from DBR-23 fermentation product against 12 animal pathogens including Shigella dysenteriae and so on were 1-2 g/L.Fermentation product of DBR-12 showed no antibacterial activity against animal pathogens.The endophytic fungi DBR-12 and DBR-23 from Stephania kwangsiensis Lo.have good antibacterial activity and exhibit a good developmental prospect in the field of antimicrobial agent.