The influences of eight metal ions (
i.e., Na
+, Ca
2+, Ag
+, Co
2+, Cu
2+, Al
3+, Zn
2+, and Mn
4+) on mycelia growth and palmarumycins C
12 and C
13 production in liquid culture of the endophytic fungus
Berkleasmium sp. Dzf12 were investigated. Three metal ions, Ca
2+, Cu
2+ and Al
3+ were exhibited as the most effective to enhance mycelia growth and palmarumycin production. When calcium ion (Ca
2+) was applied to the medium at 10.0 mmol/L on day 3, copper ion (Cu
2+) to the medium at 1.0 mmol/L on day 3, aluminum ion (Al
3+) to the medium at 2.0 mmol/L on day 6, the maximal yields of palmarumycins C
12 plus C
13 were obtained as 137.57 mg/L, 146.28 mg/L and 156.77 mg/L, which were 3.94-fold, 4.19-fold and 4.49-fold in comparison with that (34.91 mg/L) of the control, respectively. Al
3+ favored palmarumycin C
12 production when its concentration was higher than 4 mmol/L. Ca
2+ had an improving effect on mycelia growth of
Berkleasmium sp. Dzf12. The combination effects of Ca
2+, Cu
2+ and Al
3+ on palmarumycin C
13 production were further studied by employing a statistical method based on the central composite design (CCD) and response surface methodology (RSM). By solving the quadratic regression equation between palmarumycin C
13 and three metal ions, the optimal concentrations of Ca
2+, Cu
2+ and Al
3+ in medium for palmarumycin C
13 production were determined as 7.58, 1.36 and 2.05 mmol/L, respectively. Under the optimum conditions, the predicted maximum palmarumycin C
13 yield reached 208.49 mg/L. By optimizing the combination of Ca
2+, Cu
2+ and Al
3+ in medium, palmarumycin C
13 yield was increased to 203.85 mg/L, which was 6.00-fold in comparison with that (33.98 mg/L) in the original basal medium. The results indicate that appropriate metal ions (
i.e., Ca
2+, Cu
2+ and Al
3+) could enhance palmarumycin production. Application of the metal ions should be an effective strategy for palmarumycin production in liquid culture of the endophytic fungus
Berkleasmium sp. Dzf12.
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