Enhancement of Palmarumycin C(12) and C(13) Production by the Endophytic Fungus Berkleasmium sp. Dzf12 in an Aqueous-Organic Solvent System

The endophytic fungus Berkleasmium sp. Dzf12, isolated from Dioscorea zingiberensis, was found to produce palmarumycins C(12) and C(13) which possess a great variety of biological activities. Seven biocompatible water-immiscible organic solvents including n-dodecane, n-hexadecane, 1-hexadecene, liquid paraffin, dibutyl phthalate, butyl oleate and oleic acid were evaluated to improve palmarumycins C(12) and C(13) production in suspension culture of Berkleasmium sp. Dzf12. Among the chosen solvents both butyl oleate and liquid paraffin were the most effective to improve palmarumycins C(12) and C(13) production. The addition of dibutyl phthalate, butyl oleate and oleic acid to the cultures of Berkleasmium sp. Dzf12 significantly enhanced palmarumycin C(12) production by adsorbing palmarumycin C(12) into the organic phase. When butyl oleate was fed at 5% (v/v) in medium at the beginning of fermentation (day 0), the highest palmarumycin C(12) yield (191.6 mg/L) was achieved, about a 34.87-fold increase in comparison with the control (5.3 mg/L). n-Dodecane, 1-hexadecene and liquid paraffin had a great influence on the production of palmarumycin C(13). When liquid paraffin was added at 10% (v/v) in medium on day 3 of fermentation, the palmarumycin C(13) yield reached a maximum value (134.1 mg/L), which was 4.35-fold that of the control (30.8 mg/L). Application of the aqueous-organic solvent system should be a simple and efficient process strategy for enhancing palmarumycin C(12) and C(13) production in liquid cultures of the endophytic fungus Berkleasmium sp. Dzf12.