Purification and characterization of β-1,3-xylanase from a marine bacterium, Alcaligenes sp. XY-234

Abstract

A β-1,3-xylanase-producing bacterium, Alcaligenes sp. XY-234, was isolated from the marine environment. The organism produced endo-1,3-β-xylanase at a high level in the culture fluid. The enzyme was purified 292-fold by ammonium sulfate precipitation and several column chromatographies. The final enzyme preparation appeared to be homogeneous on disc gel electrophoresis and SDS-PAGE with a molecular mass of 59 kDa, and the pl was 4.0. The enzyme hydrolyzed β-1,3-xylan and larger xylooligosaccharides than xylobiose to give several xylooligosaccharides, but it could not hydrolyze xylobiose, p-nitrophenyl-β-D-xyloside, and β-1,4-xylan. The K_m of the enzyme was 4.0 mg/ml. Optimal pH and temperature were 7.5 and 40°C, respectively. It was stable from pH 6.0 to 10 and at a temperature of less than 40°C. The enzyme was strongly inhibited by 1 mM HgCl₂, AlCl₃, CuCl₂, FeCl₃, HgCl₂, Pb(CH₃COO)₂, and N-bromosuccinimide.