Enhancement of diepoxin ζ production in liquid culture of endophytic fungus Berkleasmium sp Dzf12 by polysaccharides from its host plant Dioscorea zingiberensis

This study is the first report of the enhancement of diepoxin zeta production in liquid culture of the endophytic fungus Berkleasmium sp. Dzf12 by the polysaccharides from its host plant Dioscorea zingiberensis which serve as elicitors. Three polysaccharides, namely water-extracted polysaccharide (WEP), sodium hydroxide-extracted polysaccharide and acid-extracted polysaccharide were sequentially prepared from the rhizomes of D. zingiberensis. Among them, WEP was found to be the most effective elicitor to enhance diepoxin zeta production. When WEP was added to the medium at 400 mg l(-1) on day 3 of culture, the maximal diepoxin zeta yield (intracellular diepoxin zeta in mycelia plus extracellular diepoxin zeta in medium) of 350.76 mg l(-1) on day 15 was achieved, which was about 2.69-fold in comparison with that (130.43 mg l(-1)) of the control.