CONCLUSION

Based on CFD technology, a model was established to evaluate two important parameters, oxygen supply level and mixing efficiency of microtiter plates. The reliability of the model was verified by comparing it with the experimental literature data. In order to achieve high-throughput culturing and screening of DHA producing strains, the existing microplates were evaluated and modified. The superiority of microplates with hexagonal cross sections was determined. In the follow-up research, a high-precision RSM model based on the numerical calculation results of CFD was established. Baffles were introduced and reaction parameters (liquid filling volume and rotation speed) were optimized to improve oxygen transport and mixing efficiency in the new bioreactor. Finally, a hexagonal bioreactor with 6 baffles was developed. It has a liquid filling capacity of 15% and a rotation speed of 800 rpm. A KLa of 0.61 s-1 can be achieved, which is sufficient to meet the oxygen supply requirements of DHA producing strains, and provides the perfect mixing effect. This result was also verified in subsequent experiments and the liquid splashing problem was solved. The robustness of the strains was better than that under ordinary culture conditions. Furthermore, using the new microplate, a high-quality DHA producing strain was screened and the culture conditions were optimized. The new microtiter plate model designed in this paper provides not only a good model for the culture screening of DHA-producing strains but also a good new idea for the high-throughput culture screening of many high oxygen-consuming microorganisms in the future.