链霉菌产木聚糖酶条件和酶学性质以及重离子诱变对产酶的影响研究

Studies on the Cultured Condition and Nature of Xylanase and Effects of Heavy-ion Beam Irradiation on Xylanase Produced by Streptomyces sp.

以一株由青藏高原牦牛粪中分离出的链霉菌为出发菌株,对其培养特性、产酶条件和酶学性质进行初步研究。通过重离子诱变,筛选出遗传稳定的高产菌株。结果表明,该菌以玉米芯和麸皮(1:1)为碳源能高效地诱导木聚糖酶的胞外分泌,其最适培养基和培养条件氮源为酵母膏、初始pH7、培养温度为25℃,在此条件下,第4天酶活力达到峰值3 480.25 U/mL,说明该酶能够利用农业废弃物高效生产木聚糖酶。该菌株所产木聚糖酶的最适反应温度为15℃、pH4,属低温酸性木聚糖酶。经重离子诱变后,筛选出一株高产菌株SZ10-7,其酶活力可达5 338.42 U/mL。

The growth property of Streptomyces sp. ,a xylanase producing strain,isolated from the yak dung in Qinghai-tibet plateau and the nature of xylanase were studied in this paper. The results showed that the optimal carbon source was the mixture of the corn cobs and the wheat bran（ 1：1 ） ,and the best nitrogen source was the yeast extract for the xylanase production of Streptomyces sp.. The optimal initial pit was 7 and the growth temperature was 25~C. Under the optimal condition,the highest xylanase activity of 3 480. 25 U/mL was obtained at the fourth day of incubation. The optimal reactive temperature and pH of xylanase produced by Streptomyces sp. were 15℃ and pH4, respectively, indicating that this enzyme is belong to low temperature and acidic xylanase. Xylanase activity could reach 5 338.42 U/mL by heavy ion beaming.