Immobilization of lipase onto cellulose ultrafine fiber membrane for oil hydrolysis in high performance bioreactor

Practical application of biphasic enzyme-immobilized membrane bioreactors (EMBR) requires efficient loading of the enzyme with retention of enzymatic activity. Here, we report a method to fabricate an ultrafine fiber membrane conjugated to lipase with high levels of enzyme loading and activity retention. A cellulose acetate (CA) non-woven ultrafine fiber membrane was prepared with 200 nm nominal fiber diameter by electrospinning, followed by alkaline hydrolysis to obtain regenerated cellulose (RC). The RC ultrafine fiber membrane was oxidized by exposure to NaIO₄, simultaneously generating aldehyde groups to couple with pentaethylenehexamine (PEHA) as a spacer for lipase immobilization. A biphasic EMBR was assembled with the PEHA-modified and lipase-immobilized membranes. The effect of operation variables, namely aqueous-phase system, reaction pH, accelerant (sodium taurocholate) content, reaction temperature, and membrane usage on the performance of this bioreactor was investigated with the hydrolysis of olive oil. A bioreactor activity as high as 9.83 × 10⁴ U/m² was obtained under optimum operational conditions.