出芽短梗霉菌PA-2脂肽类物质抑菌活性及其发酵条件优化

探究出芽短梗霉菌(Aureobasidium pullulans)PA-2脂肽类物质的抑菌活性,并以脂肽类物质的产量为响应值对其发酵条件进行优化,为脂肽类物质的生产与应用奠定理论基础。采用酸沉淀法对脂肽类物质进行粗提,通过原位酸水解-茚三酮显色法对脂肽粗提物进行定性检测,并用琼脂打孔扩散法对其抑菌活性进行测定,通过中心组合设计(central composite design,CCD)构建响应面对其发酵条件进行优化。最终初步判定粗提物为环状脂肽类物质;该物质对金黄色葡萄球菌(Staphylococcus aureus)、酿酒酵母菌(Saccharomyces cerevisiae)、大肠埃希菌(Escherichia coli)、樱桃球腔菌(Mycosphaerella cerasella)和大麦网斑病(Pyrenophora teres)具有明显的抑制作用,抑菌圈分别为3.65、1.95、2.15、1.35、2.18 cm;优化后的最适发酵条件为:接种量6.8%、转速216 r·min ^-1、温度26 ℃、装液量125 mL、pH 7。在此条件下模型预测的脂肽类物质产量为0.94 g·L ^-1,实际为0.92 g·L ^-1,比优化前的产量(0.61 g·L ^-1)提高了51%。优化后的发酵条件可提高脂肽类物质产量,降低发酵成本,可用于上述有抑制效果的菌株防治。

Antibacterial activities and optimization of fermentation conditions of lipopeptides produced by Aureobasidium pullulans PA-2

The antibacterial activities of lipopeptides from Aureobasidium pullulans PA-2 was explored, and the fermentation conditions were optimized with the output of lipopeptides as the response value, laying a theoretical foundation for the production and application of lipopeptides. The lipopeptides was crudely extracted by acid precipitation method. The crude extract of lipopeptide was qualitatively detected by in-situ acid hydrolysis and ninhydrin colorimetry. Antibacterial activities were measured by the method of agar drilling diffusion. The fermentation conditions were optimized by central composite design (CCD). Finally, the crude extract was identified as cyclic lipopeptide. The lipopeptides had obvious effects on Staphylococcus aureus, Saccharomyces cerevisiae, Escherichia coli, Mycosphaerella cerasella, Pyrenophorateres drechsler and antibacterial circle were 3.65, 1.95, 2.15, 1.35 and 2.18 cm respectively. The optimal fermentation conditions were: inoculation amount 6.8%, rotation speed 216 r·min ^-1, culture temperature 26 ℃, liquid volume 125 mL and initial pH 7.Under this condition, predicting yield of antibacterial lipopeptides by the model was 0.94 g·L ^-1, actually 0.92 g·L ^-1, which was 51% more than that of before(0.61 g·L ^-1). The optimized fermentation conditions increase the yield of the lipopeptide and reduce the fermentation cost, which may be applied to the control of strains with inhibitory effect above