Statistical optimization of culture medium for production of exopolysaccharide from endophytic fungus Bionectria ochroleuca and its antitumor effect in vitro

摘要

Endophytic fungi have been recognized as possible useful sources of bioactive metabolites. However, exopolysaccharide(EPS) production from endophytic fungi and its antitumor activity have been less explored. In thepresent study, endophtic fungus Bionectria ochroleuca M21 was exploited for the production of EPS in submergedculture. Among tested medium components, glucose, yeast extract, MgSO4 and Tween80 were found tobe effective and significant on EPS production. Response surface methodology (RSM) was employed to optimizemedium composition. The results showed that the significant factors were glucose, yeast extract andTween80. The optimal medium was observed at the composition of glucose 55.7 g/L, yeast extract 6.04 g/L,MgSO4 0.25g/L and Tween80 0.1 % (v/v). Using the optimized medium, EPS production was achieve at2.65 ± 0.16 g/L after 4 days fermentation in a 5L bioreactor. Examination of cytotoxicity showed that the EPSfrom B. ochroleuca M21 did not have cytotoxic activity on human liver HL-7702 cells at concentration 0.025–1.6 mg/mL. In contrast, the EPS exhibited antiproliferative activities against cell lines of liver cancer (HepG2),gastric cancer (SGC-7901) and colon cancer (HT29) in a dose- and time-dependent manner in the concentrationranges of 0.1-0.45 mg/mL.