Optimization of Cellulase and Xylanase Production by Micrococcus Species under Submerged Fermentation

Ziyanda Mmango-Kaseke,Uchechukwu Nwodo,Leonard Mabinya,Kunle Okaiyeto,Anthony Okoh

doi:10.3390/su8111168

Abstract

This paper reports on the optimization of culture conditions for cellulase and xylanase production by bacterial isolate from lignocellulosic biomass. The bacterial isolate was screened for cellulase and xylanase production on carboxyl methyl cellulose (CMC) and birch wood xylan as substrates, respectively. One bacterial isolate showing the highest halo zone diameter (isolate PLY1) was selected for detailed studies. The analysis of the 16S ribosomal ribonucleic acid (rRNA) gene nucleotide sequence of PLY1 revealed it to have 98% similarity to Micrococcus luteus strain Fse9 and the sequence was deposited in the GenBank as Micrococcus luteus strain SAMRC-UFH3 with accession number KU171371. Cellulase production was achieved in the presence of CMC (1% w/v) under an incubation temperature of 25 °C (198 U/mL), pH 5 (173 U/mL), agitation speed 50 rpm (173 U/mL) and incubation period of 96 h (102 U/mL). Xylanase was produced maximally when birch wood xylan (1% w/v) was used as the substrate at 25 °C (1007 U/mL), pH 10 (2487 U/mL), 200 rpm (1814 U/mL), and under an incubation period of 84 h (1296 U/mL). Our findings showed that Micrococcus sp. SAMRC-UFH3 appears to be a potentially important candidate for lignocellulosic waste degradation and other relevant industrial applications.

Highlights

Lignocellulose is the main structural constituent of woody plants and non-woody plants, such as grass, that constitutes a major source of renewable organic matter, comprised of lignin, hemicellulose, and cellulose [1]
Cellulase and xylanase-producing bacterial isolates were obtained from sawdust samples/wood shavings from Melani village around Alice Town in the Eastern Cape Province of South Africa
A total of 58 bacterial isolates were obtained from wood shavings and nine isolates with marked distinct colony characteristics were screened for cellulose degradation

Summary

Introduction

Lignocellulose is the main structural constituent of woody plants and non-woody plants, such as grass, that constitutes a major source of renewable organic matter, comprised of lignin, hemicellulose, and cellulose [1]. Cellulase is a complex enzyme system that plays an important role in the environment in the degradation of cellulose with subsequent conversion into useful products. It can be utilized as a part of textile industry for “bio-cleaning” of fabrics and making stone washed look of denims, as well as in the household cleansers for enhancing fabric softness and brightness. Just as with cellulase, plays a critical role in the degradation of plant biomass; its production has attracted the attention of many researchers It has various applications, incorporating biodegradation of lignocelluloses in food, animal feed, textiles, bio-deinking of waste paper, kraft pulp bleaching, and bio-pulping in the pulp and paper industry [4]. Pulps derived during kraft pulping and waste paper deinking processes at high temperature and alkaline pH need novel microbial isolates with the ability to produce thermo-tolerant and alkalophilic xylanases [6,7]

Methods

Results

Conclusion