浅白隐球酵母产油工程菌液体深层发酵技术研究

Submerged Fermentation Technology for Fatty Produced Strain of Cryptococcus albidus

为优化浅白隐球酵母液体深层发酵技术,采用已优化的培养基配比,设置不同的搅拌速率、通气量和pH值,在发酵过程中检测了溶氧消耗、pH值、生物量等指标,对影响浅白隐球酵母转基因工程菌株发酵主要工艺参数进行了研究。结果表明:优化后的发酵培养基(g/L)配方为葡萄糖30,(NH4)2SO43、酵母粉2,KH2PO41,MgSO4.7H2O 0.5;装液量7.5 L、接种量10%(v/v)、罐压0.03～0.05 MPa、培养温度28℃和搅拌速度250 r/min;通气量初始为1∶0.6,进入对数生长期后调为1∶0.85,初始pH值为6,进入对数生长期后调节为4。在以上优化条件下,进行了10 L发酵罐放大试验,培养时间为60 h时,浅白隐球酵母丝体生物量达到最大值,生物转化率达到12.34%。气相色谱检测结果表明,该菌株油脂的油酸组分较高、硬脂酸组分较低。

Based on previous optimized media in shaking-flask culturing tests, the fermentation conditions in submerged culture of Cryptococcus albidus were designed by setting different agitating speeds, aeration rates and pH values to investigate biochemical indicators including the consumption of dissolved oxygen, pH value, biomass, etc., and then the impacts of each above-mentioned factor on fermentation effect were analyzed. Moreover, through studying the fermentation characters of transgenic engineering strain of Cryptococcus albidus in fermentor with different process parameters, the submerged fermentation technologies for Cryptococcus albidus were optimized. The results showed that the formula of optimized fermentation media was 30 g/L of glucose, 3 g/L of （NH4）2SO4, 2 g/L of yeast extract, 1 g/L of KH2PO4, 0.5 g/L of MgSO4·7H2O. The optimum conditions for fermentation were 7.5 L of liquid volume in flask, 10% （v/ v） of inoculation amount, 0.03-0.05 MPa of pressure, culture temperature of 28℃ and agitating speed of 250 r/min; initial aeration ratio and initial pH value were controlled at 1：0.6 and 6, and then they were respectively adjusted to 1：0.85 and 4.0 after step into logarithmic growth phase. With the optimized conditions, a scale-up test was conducted with 10 L of fermentor and cultured for 60 h, the biomass of Cryptococcus albidus reached maximum and the biological transformation ratio reached 12.34%. The results of gas chromatography indicated that the lipin of the strain has high oleic acid content and low stearic acid content.