半疏水晶胶微球的悬浮特性及固载乳杆菌合成有机酸

Suspension characteristics of semi-hydrophobic cryogel beads and their application in Lactobacillus paracasei cell immobilization for organic acid production

针对有机酸生物合成过程中底物和产物抑制、细胞密度低和耐受性弱等问题,采用“结晶致孔-低温聚合”方法制备聚甲基丙烯酸羟乙酯-甲基丙烯酸丁酯半疏水晶胶微球,通过高速成像和数值模拟研究10 L搅拌式生物反应器(STR)内的悬浮行为,通过固载乳杆菌分析半疏水晶胶微球在乳酸和苯乳酸生物合成中的作用。结果表明,数值模拟得到晶胶微球的悬浮特性与高速成像实验结果基本一致,体积分数为3%的晶胶微球均匀悬浮所需最低搅拌转速为55 r·min-1;在晶胶固载乳杆菌发酵联产乳酸和苯乳酸过程中,乳杆菌生物量达10.5 g·L^(-1),相比于无载体发酵提高了84.2%;在第1次补料期间,乳酸的发酵周期大幅缩短至21 h,比无载体发酵周期缩短了50%。

In order to solve the problems of substrate and product inhibition,low cell density and organic acid tolerance,poly(hydroxyethyl methacrylate-butyl methacrylate)semi-hydrophobic cryogel beads were prepared by"crystallization pore-forming and low temperature polymerization",and their suspension behaviors in a 10 L stirred bioreactor were investigated by high-speed imaging and numerical simulation.Lactic acid and phenyllactic acid biosynthesis processes were studied using these cryogel bead immobilized Lactobacillus.The results show that the suspension characteristics of the cryogel beads obtained by numerical simulation are consistent with those of high-speed imaging,and the minimal stirring rate required for uniform suspension of cryogel beads(volume fraction is 3%)is 55 r·min^(-1).The Lactobacillus biomass reached 10.5 g·L^(-1) in the co-production process of lactic acid and phenyllactic acid,which was increased by 84.2% compared with Lactobacillus fermentation without immobilization.During the first feeding period,the fermentation period of lactic acid was greatly shortened to 21 h,which was 50%shorter than that without immobilization.