1Department of Biochemistry, University of Rajshahi, Bangladesh.
2Department of Applied Microbiology, University of Tohoku, Japan.
*Corresponding author
Aeromonas caviae W-61 produced five types of xylanases 1,2,3,4, and 5 extracellularly. Xylanases 1,2,3,4, and 5 have been purified to homogeneity by using ultrafiltration, salt precipitation with ammonium sulphate and column chromatographies with DEAE-Toyopearl 650M, CM-sephadex C-50 and hydroxylappatite, followed by high performance liquid chromatography with a TSK gel phenyl-5PW and DEAE-5PW column. The purified xylanases 1,2,3,4, and 5 consists of single polypeptides with molecular masses of 22, 41, 58, 120 and 140 Kda, respectively.
The optimum pH and temperature of xylanases 1,2,3,4, and 5 were 7.0, 5.5, 5.0, 6.0 and 6.0 and 55°C, 45°C, 50°C, 40°C and 40°C respectively. These xylanases showed no activity towards cellulose, CM-cellulose, arabinose and β-1,3 xylan. These five types of xylanases degraded β-1,4-xylan, producing a mixture of different types of xylo-oligosaccharides such as xylobiose, xylotriose, xylotetraose, xylopentaose and xylohexose. Its action patterns on β-1,4-xylan indicate thatthey are β-1,4-endoxylanase.
