目的:生物聚合物的微生物生产通常与高粘度有关,适当的混合在其生产中起着重要作用。由于链球菌菌株的性质,乳酸的产量高,因此NaOH的消耗量高,这与透明质酸产生引起的粘度增加和混合减少有关,注入的NaOH积聚并导致细胞损失,并且所产生的透明质酸的数量和质量降低。
结果:在这项研究中,在NaOH控制pH值期间,增加兽疫链球菌补料分批培养培养基的稀释对混合时间的影响,体积氧传递系数,并研究了在2-L发酵罐中增加透明质酸的产量。结果表明,显著增加稀释导致减少混合时间,显著提高了体积氧传递系数,透明质酸产量从6.6g/L提高到8.4g/L,减少NaOH的消耗。
结论:用pH控制剂稀释兽疫链球菌补料分批培养的培养基培养物达到了最近报道的最高透明质酸量之一。该方法不需要任何自动控制,并且可以低成本用于生产其它可溶性细胞外生物聚合物。
OBJECTIVE: Microbial production of biopolymers is typically associated with high viscosity and suitable mixing plays an important role in their production. Due to the nature of Streptococcus strains in high production of lactic acid and consequently high consumption of NaOH, which is associated with increased viscosity and reduced mixing caused by hyaluronic acid production, the injected NaOH accumulates and causes cells loss, and decreases in quantity and quality of the produced hyaluronic acid.
RESULTS: In this study, the effect of increasing dilution of media culture of Streptococcus zooepidemicus fed-batch culture during pH control by NaOH on mixing time, volumetric oxygen transfer coefficient, and increasing hyaluronic acid production in a 2-L fermenter were studied. The results showed that significant increasing dilution causes reduction mixing time, remarkable improvement volumetric oxygen transfer coefficient, hyaluronic acid production enhancement from 6.6 to 8.4 g/L, and diminution the consumption of NaOH.
CONCLUSIONS: Dilution of media culture of S. zooepidemicus fed-batch culture by the pH controlling agent achieved one of the highest amounts of hyaluronic acid that was reported recently. This method does not require any automatic control and can be used at a low cost to produce other soluble extracellular biopolymers.