从香港海岸红树林分离到的77株真菌中有34株可产生木聚糖酶,从中选出CY2809(Staganospora sp.)、CY4786和CY5040等3菌株与已知陆生产酶菌株HU5048(Aspergillus awamori)进行产木聚糖酶的比较研究.根据培养液中菌丝生物量、木聚糖酶活力和木糖等价还原糖含量等指标的测定,菌株CY4786在起始pH 7.8的木聚糖-酵母膏-海盐液体培养基中25℃下震荡(100r/min)培养7d产酶最佳;粗酶液在50q℃和pH 4.6的优化条件下进行测定,木聚糖酶活力达到1.07×104U/mL.结果表明,红树林真菌起着半纤维素降解者的作用,沿海红树林环境中存在着可资利用的木聚糖酶产生菌.作者讨论了利用发酵液中木糖等价还原糖含量的动态变化作为快速筛选产木聚糖酶菌株的指标的可能性.%Xylanase activity was detected among 34 of 77 fungal isolates derived from decaying wood, debris and soil samples collected in coastal mangrove environment of Hong Kong. Of those, three isolates CY2809 (Staganospora sp. ), CY4786 and CY5040 were chosen for comparison of xylanase production in parallel to HU5048 ( Aspergillus awamori ), a terrestrial, highly productive isolate. Based on the assessment of mycelial biomass, xylanase activity and content of xylose-equivalent reducing sugars in their liquid cultures, the isolate CY4786 was best for xylanase production in a basal medium containing birchwood xylan (10.0 g/L)as a sole carbon source, yeast extract (2.5 g/L) and sea salts (15.0 g/L) with initial pH 7.8. When assayed at the optimized regime of 50℃ and pH 4.6, the activity of xylanase produced by CY4786 in 7d liquid culture at 25℃ reached 1.07 × 104 unit/mL. The results indicate that the mangrove fungi act as hemicellulose decomposers in the mangrove environment where highly xylanaseproductive isolates can be searched for exploitation. A discussion is given on the possible use of the content of xylose-equivalent reducing sugars as an index to simplify conventional xylanase activity assay method for fungal isolate survey.
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