Purification of Gastrodin from Microbial Fermentation Broth by High Anti-Fouling Tight Ultrafiltration Membrane

Ceramic membranes are suitable for the efficient separation of functional components from microbial fermentation broths. However, the issues of flux decline and irreversible membrane fouling must be considered. In this paper, the use of tight ultrafiltration (UF) ceramic membranes is proposed to reduce membrane fouling, simplify the filtration process, and extend membrane life during fermentation broth separation. Although the membrane resistance of the tight UF membranes increased owing to their smaller pore size, the stable flux of the membrane during fermentation broth filtration of gastrodin was 28.0% higher than that of loose UF membranes, and the flux recovery ratio reached 97.3%. This is because the tight UF membrane has a narrow pore-size distribution and almost 100% retention of the protein, thus demonstrating its improved anti-fouling performance. During fermentation broth filtration, the average flux of a multi-channel tight UF membrane reached 56 L·m-2·h-1, and the total yield of gastrodin reached 96.2%. The culture medium, bacterial cells, and proteins were removed using a one-step tight UF membrane separation process, which improved the quality and efficiency of the complex fermentation broth separation. This study provides a basis for the design of membrane materials and enhanced application of fermentation broth systems.