Optimization and Characterization of Chitosan Enzymolysis by Pepsin.

Bi Gohi,Hong-Yan Zeng,A Pan

doi:10.3390/bioengineering3030017

Abstract

Pepsin was used to effectively degrade chitosan in order to make it more useful in biotechnological applications. The optimal conditions of enzymolysis were investigated on the basis of the response surface methodology (RSM). The structure of the degraded product was characterized by degree of depolymerization (DD), viscosity, molecular weight, FTIR, UV-VIS, SEM and polydispersity index analyses. The mechanism of chitosan degradation was correlated with cleavage of the glycosidic bond, whereby the chain of chitosan macromolecules was broken into smaller units, resulting in decreasing viscosity. The enzymolysis by pepsin was therefore a potentially applicable technique for the production of low molecular chitosan. Additionally, the substrate degradation kinetics of chitosan were also studied over a range of initial chitosan concentrations (3.0~18.0 g/L) in order to study the characteristics of chitosan degradation. The dependence of the rate of chitosan degradation on the concentration of the chitosan can be described by Haldane’s model. In this model, the initial chitosan concentration above which the pepsin undergoes inhibition is inferred theoretically to be about 10.5 g/L.

Highlights

Chitosan is a natural polysaccharide, which is widely distributed among living organisms in nature and has been studied extensively in the last few decades
Pepsin has attracted the most attention from researchers on account of its capability to produce the highest yield of low molecular weight (LMW) chitosan in enzymolysis [12]
In terms of the significant coefficients, the independent variables p, T and E were highly significant terms (p ď 0.0001); pH P affects the solubility of chitosan before all other reactants, while pepsin through its concentration E under control of temperature T proceeds to the hydrolysis of chitosan

Summary

Introduction

Chitosan is a natural polysaccharide, which is widely distributed among living organisms in nature and has been studied extensively in the last few decades. Its limited application in medicine and the food industry is attributed to its high molecular weight, giving it low solubility in aqueous media. The LMW chitosan has great solubility, which makes it a good candidate for DNA and drug delivery systems [9,10]. It shows potential germicidal activities against pathogenic bacteria, yeast and filamentous fungus [11]. Many enzymes with different original specificities, such as cellulase, pectinase, pepsin, papain and lipase, have been reported to have the ability to hydrolyze chitosan [1]. The enzymolysis process of chitosan degradation by papain has been exhaustively described in our previous study (Pan et al, 2016) [13]

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Conclusion