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A novel Bacillus pumilus strain for alkaline xylanase production at and above 40°C

Authors:

R Kapilan ,

Department of Botany, Faculty of Science, University of Jaffna, LK
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Vasanthy Arasaratnam

Department of Biochemistry, Faculty of Medicine, University of Jaffna, LK
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Abstract

The objective of the study was to select a bacterial strain which can produce xylanase at alkaline pH and temperatures above 40°C and to characterize the strain. Among the 45 bacterial strains, isolated from different sources, five strains, which were expected to produce alkaline xylanase, above 40°C, isolated from open media containing xylan as carbon source (GS7, GS15, GS17, GS20 & GS*), were selected for the study. Xylanase production by the strains GS17 and GS*, was less affected by pH changes between pH 8.0 and 9.5 than the strains GS7, GS15 and GS20. Strains GS17 and GS* produced xylanase at pH 10.0 while the others did not produce. Therefore strains GS17 and GS* were selected. Xylanase production, by GS17 at 39 hours was 1.2, 1.3, 1.2 and 3.2 times higher at 40, 45, 50 and 55°C than by GS*. At 60°C, GS17 produced 4.25 UmL-1 (30h) of xylanase activity while GS* did not. As GS17 produced xylanase at and above pH 9.0 and 40 to 60°C, it was selected. The xylanase of GS17 showed activity in the temperature range from 40 to 95°C showing highest activity at 60°C. Strain GS17 is non-branching, gram-positive, sporulating, motile, aerobic, catalase positive, β hemolytic, oxidase positive long rods. Hence, it belongs to the genus Bacillus. Slightly oval shaped terminal and subterminal endospores were observed in 24h old cultures. When the culture became old, formation of spores was very much reduced. Further, based on the shape and arrangement of spores, ability to produce acid from glucose, xylose & mannose; growth temperature; inability to hydrolyze starch and tyrosine; inability to produce urease and indole; inability to reduce nitrate; ability to grow in NaCl and ability to grow in different carbohydrate sources, the strain, GS17 was identified as Bacillus pumilus. Thus, Bacillus pumilus which was locally isolated can grow and produce xylanase at and above 40°C and pH 9.0.

Key words: alkaline xylanase; Bacillus pumilus; carbon source.

DOI: 10.4038/cjsbs.v39i1.2354

Cey. J. Sci. (Bio. Sci.) 39 (1): 61-70, 2010

How to Cite: Kapilan, R. & Arasaratnam, V., (2010). A novel Bacillus pumilus strain for alkaline xylanase production at and above 40°C. Ceylon Journal of Science (Biological Sciences). 39(1), pp.61–70. DOI: http://doi.org/10.4038/cjsbs.v39i1.2354
Published on 12 Oct 2010.
Peer Reviewed

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