Production of thermotolerant and alkalotolerant cellulolytic enzymes by isolated <Emphasis Type="Italic">Nocardiopsis</Emphasis> sp. KNU |
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Authors: | Ganesh D Saratale Sang Eun Oh |
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Institution: | (1) Department of Biochemistry, Shivaji University, Kolhapur, Maharashtra, 416004, India;(2) Bioenergy Laboratory, Department of Biological Environment, College of Agriculture and Life Sciences, Kangwon National University, Chuncheon, Gangwondo, 200-701, South Korea; |
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Abstract: | A novel cellulolytic bacterium was isolated from the forest soil of KNU University campus. Through 16S rRNA sequence matching
and morphological observation it was identified as Nocardiopsis sp. KNU. This strain can utilize a broad range of cellulosic substrates including: carboxymethyl cellulose (CMC), avicel,
xylan, cellobiose, filter paper and rice straw by producing a large amount of thermoalkalotolerant endoglucanase, exoglucanase,
xylanase and glucoamylase. Optimal culture conditions (Dubos medium, 37°C, pH 6.5 and static condition) for the maximal production
of the cellulolytic enzymes were determined. The activity of cellulolytic and hemicelluloytic enzymes produced by this strain
was mainly present extracellularly and the enzyme production was dependent on the cellulosic substrates used for the growth.
Effect of physicochemical conditions and metal additives on the cellulolytic enzymes production were systematically investigated.
The cellulases produced by Nocardiopsis sp. KNU have an optimal temperature of 40°C and pH of 5.0. These cellulases also have high thermotolerance as evidenced by
retaining 55–70% activity at 80°C and pH of 5.0 and alkalotolerance by retaining >55% of the activity at pH 10 and 40°C after
1 h. The efficiency of fermentative conversion of the hydrolyzed rice straw by Saccharomyces cerevisiae (KCTC-7296) resulted in 64% of theoretical ethanol yield. |
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