Subramaniyan S, Prema P
Biochemical Processing and Waste Water Technology, Regional Research Laboratory (CSIR), Trivandrum, India.
FEMS Microbiol Lett. 2000 Feb 1;183(1):1-7. doi: 10.1111/j.1574-6968.2000.tb08925.x.
Xylanases are used mainly in the pulp and paper industries for the pretreatment of Kraft pulp prior to bleaching to minimize use of chlorine, the conventional bleaching agent. This application has great potential as an environmentally safe method. Hydrolysis by xylanases of relocated and reprecipitated xylan on the surface of cellulose fibres formed during Kraft cooking facilitates the removal of lignin by increasing permeability to oxidising agents. Most of the xylanases reported in the literature contained significant cellulolytic activity, which make them less suitable for pulp and paper industries. The need for large quantities of xylanases which would be stable at higher temperatures and pH values and free of cellulase activity has necessitated a search for novel enzymes. We have isolated and characterised several xylanase-producing cultures, one of which (an alkalophilic Bacillus SSP-34) produced more than 100 IU ml(-1) of xylanase activity. The SSP-34 xylanases have optimum activity at 50 degrees C in a pH range 6-8, with only small amounts of cellulolytic activity (CMCase (0.4 IU ml(-1), pH 7), FPase (0.2 IU ml(-1), pH 7) and no activity at pH 9).
木聚糖酶主要用于制浆造纸工业，在传统漂白剂氯漂白之前对硫酸盐浆进行预处理，以尽量减少氯的使用。作为一种环境安全的方法，该应用具有巨大潜力。在硫酸盐蒸煮过程中形成的纤维素纤维表面，木聚糖酶对重新定位和再沉淀的木聚糖进行水解，通过增加对氧化剂的渗透性促进木质素的去除。文献中报道的大多数木聚糖酶都具有显著的纤维素分解活性，这使得它们不太适合制浆造纸工业。由于需要大量在较高温度和pH值下稳定且无纤维素酶活性的木聚糖酶，因此有必要寻找新型酶。我们已经分离并鉴定了几种产生木聚糖酶的培养物，其中一种（嗜碱芽孢杆菌SSP - 34）产生的木聚糖酶活性超过100 IU ml(-1)。SSP - 34木聚糖酶在50摄氏度、pH值6 - 8的范围内具有最佳活性，只有少量的纤维素分解活性（羧甲基纤维素酶（0.4 IU ml(-1)，pH 7）、滤纸酶（0.2 IU ml(-1)，pH 7），在pH 9时无活性）。
