Abstract: Since dopamine can self-polymerize and adhere to the material surface in mild aqueous environments, dopamine was used for surface modification of polypropylene fiber membranes. In this paper, the effect of surface modification of polypropylene fiber membranes with dopamine on the formation of Lactobacillus paracasei biofilms was studied. The L. paracasei biofilms were characterized by scanning electron microscope, attenuated total reflectance Fourier transform infrared spectroscopy, and water contact angle measurement. The stress resistance and fermentation performance for lactic acid production were studied in detail. The results demonstrated that the dopamine layer on the surface of polypropylene fiber membranes remarkably enhanced the formation of L. paracasei biofilms. It is worth to note that as compared with the L. paracasei on polypropylene fiber membranes, L. paracasei biofilms on dopamine-modified polypropylene fiber membranes possessed higher resistance to severe environments, such as high temperature, strong acid and strong base. Besides, the purity of L-lactic acid produced by L. paracasei biofilms in a biofilm reactor was higher than 99%. The lag phase of fermentation scarcely existed, which means that high fermentation efficiency.

Key words: Lactobacillus paracasei biofilm, dopamine, polypropylene fiber membrane, biofilm reactor, L-lactic acid