| Strain S-2 with a high yield of alkaline pectinase was isolated from alkaline soil. The strain grew as a non-pigmented color and was further characterized to be Gram positive, endospore-foming, rod-shaped. The 16SrDNA sequences analyse showed that the strain S-2 has 99% sequence similarity to Bacillus gibsonii DSM 8722. Therefore the strain S-2 was dclassified as Bacillus gibsonii.Solid state fermentation conditions of the Bacillus gibsonii S-2 for production of alkaline pectinase were optimized. The results showed that sugar beet pulp was found to be the best inducer and carbon source, and yeast extract was the best nitrogen sources. The optimal fermentation medium contained: sugar beet pulp 5 g, yeast extract 1.5 g, Na2CO3 0.09 g, KH2PO4 30 mg, MgSO4·7H2O 27 mg, disolved in 15 ml water. The cultivation conditions of. Bacillus gibsonii S-2 were studied and the optimal conditions were as follows : seed age 24 h, inoculum size 2%, fermentation temperature 35 ℃ for 48h, The yield of alkaline pectinase was 3700 u/g at the above optimized conditions.The result of the extraction facture of the enzyme was that the recovery ratio of the enzyme was highest under 1 h extraction with 30 volume of Na2CO3/NaHCO3 (pH10.5). The highest activity of the enzyme was at pH 10.5 and 60 ℃. The enzyme was more stable in a broad alkaline pH range from 9.0 to 10.5 at 55 ℃ for more than 30 minute. The activity of the enzyme can maintain for a long time at 35 ℃. Metal ions such as Ca2+, Mg2+ and surface active detergents such as Tween80, Tween60, Tween20 and SDS can enhance the activity of the enzyme obviously.Alkaline pectinase was separated by micro filtration, ultra filtration, salted out with ammonium sulphate, sephadex G-25 gel, express-ion D column and sephadex G-100 gel and the alkaline pectinase were purified to two homogeneity, alkaline polygalacturonas and alkaline polygalacturonate lyases. SDS-PAGE indicated that their molecular weights were all 41 kD.
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