Fermentative Production of Mycelial Chitosan from Zygomycetes: Media Optimization and Physico-Chemical Characterization

Pradnya N Vaingankar,Archana R Juvekar

doi:10.4236/abb.2014.512108

Abstract

The present study focused on production of mycelial chitosan from fungal mycelium by submerged fermentation with ecologically more balanced process. Different fungal strains were screened and Absidia butleri NCIM 977 was found to produce the highest mycelial chitosan. The one-factor-at-a-time method was adopted to investigate the effect of batch time, environmental factors (i.e. initial pH and temperature) and medium components (i.e. carbon and nitrogen) on the yield of mycelial chitosan. Among these variables, the optimal condition to increase in yield of mycelial chitosan was found to be batch time (72 h), pH (5.5), temperature (30°C), carbon source (glucose) and nitrogen source (tryptone and yeast extract). Subsequently, a three-level Box– Behnken factorial design was employed combining with response surface methodology (RSM) to maximise yield of mycelial chitosan by determining optimal concentrations and investigating the interactive effects of the most significant media components (i.e. carbon and nitrogen sources). The optimum value of parameters obtained through RSM was glucose (1.58%), tryptone (1.61%) and yeast extract (1.11%). There was an increase in mycelial chitosan yield after media optimization by one-factor-at-a-time and statistical analysis from 683 mg/L to 1 g/L. Mycelial chitosan was characterized for total glucosamine content (80.68%), degree of deacetylation (DD) (79.89%), molecular weight (8.07 × 104 Da) and, viscosity (73.22 ml/g). The results of this study demonstrated that fungi are promising alternative sources of chitosan with high DD and high purity.

Highlights

Chitosan is a natural amino polysaccharide comprising copolymers of D-glucosamine (GlcN) and N-acetylD-glucosamine (GlcNAc), and is a deacetylated derivative of chitin—the second most abundant natural polymer after cellulose [1]
Mycelial chitosan offers significant advantages; the most important is like where crustacean waste supplies are limited by seasons and sites of fishing industry; fungal mycelium can be obtained by convenient fermentation process with organisms that can be readily cultured on cheap nutrients and the cell wall material can be recovered by simple chemical procedures
In our screening among five fungal strains, we found that A. butleri National Collection of Industrial Microorganism (NCIM) 977 gave maximum production of mycelial chitosan (401 mg/L) followed by C. echinulata NCIM 691 (372 mg/L) and R. oryaze NCIM 1009 (274 mg/L)

Summary

Introduction

Chitosan is a natural amino polysaccharide comprising copolymers of D-glucosamine (GlcN) and N-acetylD-glucosamine (GlcNAc), and is a deacetylated derivative of chitin—the second most abundant natural polymer after cellulose [1]. It is polycationic, nontoxic, biodegradable as well as antimicrobial and has been reported to have numerous applications especially in food, pharmaceutics and cosmetics [2]-[4]. Mycelial chitosan offers significant advantages; the most important is like where crustacean waste supplies are limited by seasons and sites of fishing industry; fungal mycelium can be obtained by convenient fermentation process with organisms that can be readily cultured on cheap nutrients and the cell wall material can be recovered by simple chemical procedures. Crustacean chitosan may vary in the physico-chemical properties, while mycelial chitosan has relatively consistent properties [12]-[16]

Methods

Results

Conclusion