Abstract
BackgroundThe rising concerns about the scarcity of fossil fuels, the emission of green house gasses and air pollution by incomplete combustion of fossil fuel have also resulted in an increasing focus on the use of cellulases to perform enzymatic hydrolysis of the lignocellulosic materials for the generation of bioethanol. The aim of this study was to isolate a potential thermo-solvent tolerant cellulase producing bacterium from natural resources, and then applied for purification and characterization. The purified enzyme was to be accessible for the bioethanol production as well as industrial exploitation (discuss in our next study).ResultsIt is the first instance when thermo-solvent tolerant cellulase producing bacterium was isolated from soil sample. The culture was identified as Bacillus vallismortis RG-07 by 16S rDNA sequence analysis. Bacillus vallismortis RG-07 reported maximum cellulase production from sugarcane baggase (4105 U ml−1) used as agro-waste carbon source. The cellulase enzyme produced by the Bacillus sp. was purified by (NH4)2SO4 precipitation, ion exchange and gel filtration chromatography, with overall recovery of 28.8%. The molecular weight of purified cellulase was 80 kDa as revealed by SDS-PAGE and activity gel analysis. The optimum temperature and pH for enzyme activity was determined as 65°C and 7.0 and it retained 95 and 75% of activity even at 95°C, and 9.0 respectively. The enzyme activity was enhanced in the presence of organic solvents (30%) n-dodecane, iso-octane, n-decane, xylene, toluene, n-haxane, n-butanol, and cyclohexane, after prolonged incubation (7 days). The enzyme activity was also stimulated by Ca2+, mercaptoethanol, Tween-60, and Sodium hypochloride whereas strongly inhibited by Hg. Kinetic analysis of purified enzyme showed the Km and Vmax to be 1.923 mg ml−1 and 769.230 μg ml−1 min−1, respectively.ConclusionThe unique property of solvent-thermostable-alkalophilic, nature proves the potential candidature of this isolate for current mainstream biomass conversion into fuel and other industrial process.Electronic supplementary materialThe online version of this article (doi:10.1186/s12896-015-0129-9) contains supplementary material, which is available to authorized users.
Highlights
The rising concerns about the scarcity of fossil fuels, the emission of green house gasses and air pollution by incomplete combustion of fossil fuel have resulted in an increasing focus on the use of cellulases to perform enzymatic hydrolysis of the lignocellulosic materials for the generation of bioethanol
The majority of the commercial and laboratory cellulases are achieved by fungi due to their high enzyme activity, but several factors suggest that bacteria may have excellent potential [7]
The cellulase enzyme was applied for purification and characterization of different parameters and purify enzyme was applied for the ethanol production and industrial exploitation which discuss in our study
Summary
The rising concerns about the scarcity of fossil fuels, the emission of green house gasses and air pollution by incomplete combustion of fossil fuel have resulted in an increasing focus on the use of cellulases to perform enzymatic hydrolysis of the lignocellulosic materials for the generation of bioethanol. Several microorganisms can produce cellulase enzyme including fungi, bacteria and actinomycetes. The majority of the commercial and laboratory cellulases are achieved by fungi due to their high enzyme activity, but several factors suggest that bacteria may have excellent potential [7]. Bacteria frequently have a higher growth rate than fungi allowing for higher rate of enzyme production. Most significantly, they show affinity to be more heat stable and are easier for genetic purpose. The present study was to isolate a potential organic-solventthermostable alkalophilic cellulase producing bacteria from natural ecosystem. The cellulase enzyme was applied for purification and characterization of different parameters and purify enzyme was applied for the ethanol production and industrial exploitation which discuss in our study
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