Isolation of Cellulolytic Bacillus subtilis Strains from Agricultural Environments

Yu-Kyoung Kim,Shin-Chan Lee,Young Hwan Ko,Young-Yun Cho,Hyun-Jeong Oh

doi:10.5402/2012/650563

Yu-Kyoung Kim, Shin-Chan Lee + Show 3 more

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https://doi.org/10.5402/2012/650563

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Abstract

The bioconversion of cellulose and hemicellulose to soluble sugars is important for global stabilization and a sustainable human society. Here, hundreds of cellulolytic bacteria were screened and isolated from soil, compost, and animal waste slurry in Jeju Island, South Korea. Among the isolates, three strains, SL9-9, C5-16, and S52-2, showing higher potential for practical uses were purified on carboxymethyl cellulose (CMC) agar plates and identified as Bacillus subtilis strains by morphological, physiological, and biochemical characterization and 16S rRNA gene analysis. The production patterns of cellulose or hemicellulose-degrading enzymes were investigated during cell culture. All three isolated strains produced CMCase, Avicelase, β-glucosidase, and xylanase enzymes, which suggested synergic cellulolytic systems in Bacillus subtilis. The enzymes showing CMCase, Avicelase, and xylanase activities existed in cell-free culture supernatant, meanwhile β-glucosidase activity was detected in cell debris suggesting that three of the enzymes, including CMCase, Avicelase, and xylanase, were extracellular, and β-glucosidase was cell membrane bound. The three isolates, SL9-9, C5-16, and S52-2, were not the same strains, presenting slight differences in biochemical characteristics, 16S rRNA gene sequences, and cellulolytic enzyme activities.

Highlights

The bioconversion of cellulose to soluble sugars and glucose is catalyzed by a group of enzymes called cellulases that are produced by microorganisms [1]
This paper reports the occurrence of these cellulolytic enzymes from Bacillus subtilis strains isolated from different habitats
After appropriate dilutions with sterile water, 1 mL each of the sample dilutions was spread onto carboxymethyl cellulose (CMC) agar plates that consisted of CMC, 10.0; yeast extract, 1.0; (NH4)2SO4,2.5; K2HPO4·3H2O, 0.25; NaCl, 0.1; MgSO4·7H2O, 0.125; FeSO4·7H2O, 0.0025; MnSO4·4H2O, 0.025; agar, 10(g/L, each), and the plates were incubated at 28◦C for 2 days

Summary

Research Article

Isolation of Cellulolytic Bacillus subtilis Strains from Agricultural Environments. Three strains, SL9-9, C5-16, and S52-2, showing higher potential for practical uses were purified on carboxymethyl cellulose (CMC) agar plates and identified as Bacillus subtilis strains by morphological, physiological, and biochemical characterization and 16S rRNA gene analysis. The production patterns of cellulose or hemicellulose-degrading enzymes were investigated during cell culture. All three isolated strains produced CMCase, Avicelase, β-glucosidase, and xylanase enzymes, which suggested synergic cellulolytic systems in Bacillus subtilis. The enzymes showing CMCase, Avicelase, and xylanase activities existed in cell-free culture supernatant, β-glucosidase activity was detected in cell debris suggesting that three of the enzymes, including CMCase, Avicelase, and xylanase, were extracellular, and β-glucosidase was cell membrane bound. The three isolates, SL9-9, C5-16, and S52-2, were not the same strains, presenting slight differences in biochemical characteristics, 16S rRNA gene sequences, and cellulolytic enzyme activities

Introduction

ISRN Microbiology

Materials and Methods

Results and Discussion

Growth pH rangeb

Potassium gluconate