Medium optimization for exopolysaccharide production in liquid culture of endophytic fungus Berkleasmium sp. Dzf12.

Peiqin Li,Liang Xu,Shiqiong Lu,Tijiang Shan,Ziling Mao,Ligang Zhou,Yan Mou,Youliang Peng

doi:10.3390/ijms130911411

Abstract

Berkleasmium sp. Dzf12, an endophytic fungus from Dioscorea zingiberensis, is a high producer of spirobisnaphthalenes with various bioactivities. The exopolysaccharide (EPS) produced by this fungus also shows excellent antioxidant activity. In this study, the experimental designs based on statistics were employed to evaluate and optimize the medium for EPS production in liquid culture of Berkleasmium sp. Dzf12. For increasing EPS yield, the concentrations of glucose, peptone, KH2PO4, MgSO4·7H2O and FeSO4·7H2O in medium were optimized using response surface methodology (RSM). Both the fractional factorial design (FFD) and central composite design (CCD) were applied to optimize the main factors which significantly affected EPS production. The concentrations of glucose, peptone and MgSO4·7H2O were found to be the main effective factors for EPS production by FFD experimental analysis. Based on the further CCD optimization and RSM analysis, a quadratic polynomial regression equation was derived from the EPS yield and three variables. Statistical analysis showed the polynomial regression model was in good agreement with the experimental results with the determination coefficient (adj-R2) as 0.9434. By solving the quadratic regression equation, the optimal concentrations of glucose, peptone and MgSO4·7H2O for EPS production were determined as 63.80, 20.76 and 2.74 g/L, respectively. Under the optimum conditions, the predicted EPS yield reached the maximum (13.22 g/L). Verification experiment confirmed the validity with the actual EPS yield as 13.97 g/L, which was 6.29-fold in comparison with that (2.22 g/L) in the original basal medium. The results provide the support data for EPS production in large scale and also speed up the application of Berkleasmium sp. Dzf12.

Highlights

IntroductionExtensive attention and interest have been focused on the polysaccharides prepared from fungi for their various biological activities, such as immunomodulating effects of the polysaccharides from Coriolus versicolor [1] and Hericium erinaceus [2], antioxidant activities of the polysaccharides from Cordyceps sinensis [3,4,5], Fusarium oxysporum Dzf17 [6] and Aspergillus versicolor [7], antitumor effects of the polysaccharides from Ganoderma tsugae [8] and Pholiota dinghuensis [9], anti-inflammatory effect of the polysaccharide from Fomitopsis pinicola [10], antiherpectin activity of the sulfated polysaccharide from Agaricus brasiliensis [11], antiangiogenic activity of the polysaccharide from Antrodia cinnamomea [12], anticoagulant properties of the polysaccharides fromPleurotus sajor-caju [13], and enhancement of diosgenin production in cell suspension culture of Dioscorea zingiberensis by the polysaccharides from endophytic fungus Fusarium oxysporumDzf17 [14,15]
The fractional factorial design (FFD) enables the identification of the main effect of each variable upon response, which is estimated as the difference between both averages of measurements made at the high and low levels of that factor [36,43]
Fractional factorial design (FFD) was initially employed to identify the major components of medium affecting the producing of EPS, which was very practical, especially when the investigator is faced with a large number of factors and is unsure which settings are likely to be close to optimum responses [33,53]

Summary

Introduction

Extensive attention and interest have been focused on the polysaccharides prepared from fungi for their various biological activities, such as immunomodulating effects of the polysaccharides from Coriolus versicolor [1] and Hericium erinaceus [2], antioxidant activities of the polysaccharides from Cordyceps sinensis [3,4,5], Fusarium oxysporum Dzf17 [6] and Aspergillus versicolor [7], antitumor effects of the polysaccharides from Ganoderma tsugae [8] and Pholiota dinghuensis [9], anti-inflammatory effect of the polysaccharide from Fomitopsis pinicola [10], antiherpectin activity of the sulfated polysaccharide from Agaricus brasiliensis [11], antiangiogenic activity of the polysaccharide from Antrodia cinnamomea [12], anticoagulant properties of the polysaccharides fromPleurotus sajor-caju [13], and enhancement of diosgenin production in cell suspension culture of Dioscorea zingiberensis by the polysaccharides from endophytic fungus Fusarium oxysporumDzf17 [14,15]. Extensive attention and interest have been focused on the polysaccharides prepared from fungi for their various biological activities, such as immunomodulating effects of the polysaccharides from Coriolus versicolor [1] and Hericium erinaceus [2], antioxidant activities of the polysaccharides from Cordyceps sinensis [3,4,5], Fusarium oxysporum Dzf17 [6] and Aspergillus versicolor [7], antitumor effects of the polysaccharides from Ganoderma tsugae [8] and Pholiota dinghuensis [9], anti-inflammatory effect of the polysaccharide from Fomitopsis pinicola [10], antiherpectin activity of the sulfated polysaccharide from Agaricus brasiliensis [11], antiangiogenic activity of the polysaccharide from Antrodia cinnamomea [12], anticoagulant properties of the polysaccharides from. The polysaccharides from endophytic fungi have been rarely reported except for our previous studies [6,14,15,26]

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Results

Conclusion