Propionic acid production in an external plant fibrous-bed bioreactor combined with hollow fiber membrane

Using glucose as carbon source and Propionibacterium freudenreichii CCTCC M207015 as the fermentation strain, a hollow fiber membrane combined with a novel external plant fibrous-bed bioreactor (PFB) was constructed and applied for the propionic acid production.The results show that the equipment could be efficient and stable for the repeated-batch propionic acid fermentation. After five batches of fermentation (214 h), the average batch propionic acid concentration is 50.77 g·L^-1 with a productivity of 1.19 g·L^-1·h^-1, and the maximal dry cell weight obtained is 33.85 g·L^-1. Glucose conversion efficiency and the proportion of propionic acid to total organic acids are approximately 50.77% and 79.45% (w/w), respectively. All of the data are better than that of the propionic acid production using the free cell propionic acid fermentation combined with hollow fiber membrane.