在内置式植物纤维床反应器中用糖蜜固定化发酵制丙酸

Production of Propionic Acid by Immobilized Cell Fermentation of Cane Molasses in an Inner Plant Fibrous-Bed Bioreactor

开发了一种综合利用制糖工业副产物生产丙酸的新方法,将制糖工业副产物甘蔗渣和糖蜜分别作为固定化载体和碳源,应用于丙酸生产。以甘蔗渣为固定化载体构建了一种内置式植物纤维床反应器(Inner plant fibrous-bed bioreactor,IPFB)。以Propionibacterium freudenreichii CCTCCM207015为发酵菌株,对在IPFB中分别用未处理糖蜜及糖蜜水解液为碳原发酵制丙酸进行考察。以未处理糖蜜为碳源发酵,254h丙酸浓度为52.39g·L-1,丙酸生产速率为0.21g·(L·h)-1;糖蜜水解液为碳源发酵,254h后丙酸浓度达75.18g·L-1,丙酸生产速率达0.30g·(L·h)-1,丙酸占总有机酸比例达83.10%(w/w)。稳定性实验表明以糖蜜水解液为碳源,利用IPFB发酵生产丙酸10批仍然保持较高的丙酸生产效率。扫描电镜显示大量丙酸杆菌的细胞吸附于甘蔗渣表面与间隙中,有效实现了高密度发酵。

A novel method of comprehensively utilizing the sugar-industry by-products to produce propionic acid economically and efficiently was developed. In this method, the by-products of sugar-refinery, sugarcane bagasses and cane molasses, were used as cell immobilized material and carbon source, respectively, for propionic acid production. An inner plant fibrous-bed bioreactor （IPFB） with sugarcane bagasses as support for the immobilization of the fermentation was established. Using the non-treated cane molasses and hydrolyzed cane molasses as carbon source, respectively, Propionibacterium freudenreichii CCTCC M207015 as the fermentation strain, the propionic acid fermentations were conducted. When the non-treated cane molasses was used as carbon source, after 254 h fermentation, 52.39 g·L^-1 of propionic acid can be obtained from the IPFB with a productivity of 0.21 g·（L·h）^-1; while when the hydrolyzed cane molasses was used, the maximum propionic acid yield reaches 75.18 g·L^-1 after 254 h fermentation and with a productivity of 0.30 g·（L·h）^-1, the ratio of propionic acid to total organic acids is approximately 83.10%（w/w）. The IPFB exhibits excellent production stability during several batches fermentations and the propionic acid yield remains high after ten batches of propionic acid fermentation. The SEM micrograph of the immobilized cells shows that there are numerous cells absorbed onto the surface and apertures of the cane bagasses, which effectively realize the high-density cell fermentation ofpropionic acid.