耐热木聚糖酶源细菌筛选、鉴定及酶学性质

Screening and identification of thermostable β-xylanase-producing bacteria and biochemical characterization of the enzyme

利用木聚糖作为唯一碳源的基础盐培养,在50℃培养条件下,从新乡周围土样及腐殖质中筛选到1株产耐热β-木聚糖酶细菌,初步鉴定为巨大芽孢杆菌（Bacillus megaterium FLH-2）.该菌株在40～55℃生长良好,最适生长温度50℃.木聚糖酶粗酶性质研究表明：该酶最适pH和最适温度分别为6.0和65℃;在pH 5.0～9.0及温度30～75℃之间酶活相对稳定,分别处理30 min,相对酶活仍保持在80%以上.

A thermophilic bacterium Bacillus megaterium FLH-2 possessing β-xylanase was isolated from soil and humus samples from Xinxiang and screened at 50 ℃ by using basal medium supplemented with xylan as a sole carbon source.Strain FLH-2 was capable of growing well on 40～55 ℃ and the optimum growth temperature was 50 ℃.The crude enzyme showed optimum catalytic activity at pH 6.0 and 65 ℃.The enzyme exhibited good pH stability and thermostability,with 80% relativity activity at pH 5.0～9.0 and 30～75 ℃,respectively.