Study On The Backward Extraction Of Cellulase In Rhamnolipid Reverse Micelles

Cellulose is the most abundant renewable natural biological resource, and also isan almost inexhaustible raw material. Cellulose biodegradation by cellulases is veryimportant in several agricultural and waste treatment processes. Furthermore, it couldbe widely used to produce sustainable biobased products and bioenergy to replacedepleting fossil fuels, this is important for the sustainable development of humanbeings. Cellulases must be separated and purified, in order to meet the requirementsof the research and its applications.Reverse micelles is a liquid-liquid extraction technology for bioseparation.Reverse micelles represent stabilized nanometer-sized aqueous droplets inside.Proteins were shown to be solubilized, maintaining their functional properties.Currently, a large number of domestic and international research on r everse micellesare based on chemical surfactants, it is easy to accumulate environmental pollutantsand inactivate some enzymes. Biosurfactant applications in reverse micelles arepotential due to their biodegradability and low toxicity, and may even replace thetraditional chemical surfactants. Most of the research about biosurfactant until nowhas been performed with rhamnolipids. The overall liquid-liquid extraction process byreverse micelles consists of two fundamental steps: a forward extraction and abackward extraction. People pay more attentions on the forward extraction, howeverthere are relatively few studies of the backward extraction.For this study, the purpose is to improve the backward extraction process. Thebackward extraction conditions were optimized including the aqueous phase pH, ionicspecies, ionic strength, stripping time. And the effect of were investigated as well.Reverse micellar system was constructed by using biosurfactant rhamnolipid(Rhamnolipid, RL), solvent isooctane and n-hexanol as cosolvent. The cellulases weresolubilized into2.75mmol/L RL/isooctane/n-hexanol solution by the injection method.Studies have shown that a small amount of alcohol addition can increase backwardextraction efficiency, while activity recovery decreased. The experiment resultsillustrated that the optimal conditions was: stripping aqueous pH7.0, KCl0.15mol/L,stripping time30min, dosage of n-butanol2%. Under above conditions, the backwardextraction efficiency and activity recovery were76.33%and93.39%, respectively.