Evaluation of an alginate-chitosan-microcrystalline cellulose sulfate encapsulation system for efficient fermentation of lignocellulosic hydrolyzate.

Encapsulation is one of the methods that can prevent the cells from the toxic acid hydrolyzate. Sodium microcrystalline cellulose sulfate (NaMCS) was evaluated as a supporting compound for capsule cells alginate-chitosan-microcrystalline cellulose sulfate for ethanol production from the lignocellulosic hydrolyzate. The effect of capsule preparation variables such as the composition of Na-alginate and Na-MCS, the pH of buffer acetate, and the concentration of CaCl2 as a crosslinker agent on the capsule characteristics were also investigated. NaMCS was obtained by sulfation of MCC microcrystalline cellulose (MCC) using chlorosulfonic acid-dimethylformamide complexes as a sulfation agent. NaMCS was then analyzed by IR (infrared) and HNMR spectrometry, as well as the degree of substitution (DS), using conductometry titration. The capsule compositions consist of alginate (0.45, 0.54, and 0,60%), NaMCS (0, 0.06, and 0.15%), 1.3% CMC (carboxymethylcellulose), 1.3% CaCl2, and a coating material consist of 0.2% chitosan, and (25, 50, and 50mM) CaCl2. The encapsulation method is a one-step method, liquid droplet forming. The capsule cells were used in batch fermentation using Saccharomyces cerevisiae with 50% lignocellulosic hydrolyzate media. This research revealed that the preparation of Na-MCS from microcrystalline cellulose resulted in a low degree of substitution (DS = 0.104). The low DS influenced the character of the Alg-Chit-MCS microcapsule. Increasing the concentration of Na-MCS with low DS in Alg-Chit-MCS resulted in a weak and un-spherical capsule. The optimum capsule membrane was prepared using NaMCS with a concentration of 0.06%. High ethanol yield resulted from the capsule with the composition of 0.54% alginate, 0,06% NaMCS, 1.3% CMC, 1.3% CaCl2, coating with 0.2% chitosan, CaCl2 300 mM, and pH buffer acetate of 5. Investigating the effects of Na-MCS with higher DS may be worthwhile since this may improve membrane quality. [ABSTRACT FROM AUTHOR]