棉秆非纤维素组分嗜碱性细菌生物降解及制浆研究(Ⅱ)──半纤维素降解酶-木聚糖酶性质特点研究

io degradation of Non-celulose ComponentsinCoton Stalk and Its Pulping by Alkalophilic Bacteria(Ⅱ):Properties and Characteristics of Xylanase

以玉米芯半纤维素为营养源，从７株嗜碱性细菌Ｂａｃｉｌｕｓｓｐ。ＮＴ－７、１７、１９、３２、３３、３９和６２中筛选出产木聚糖酶活性较高的两菌株ＮＴ－１９和ＮＴ－６２。对ＮＴ－１９和ＮＴ－６２所分泌的木聚糖酶初步纯化并分析它们的性质发现，ＮＴ－１９木聚糖酶ＸＥ１９和ＮＴ－６２所产木聚糖酶ＸＥ６２的最适反应温度分别为５０℃和６０℃。两者的米氏常数分别为３．７０和３．７６ｍｇ／ｍＬ。它们的Ｖｍａｘ分别为４８６和４４５μｇ／（ｍＬ·ｍｉｎ）。浓度为５ｍｍｏｌ／Ｌ的不同金属离子及某些有机试剂对木聚糖酶活有不同影响，除Ａｇ＋、Ｈｇ２＋等重金属离子完全抑制木聚糖酶活之外，其它离子及试剂大多数表现出程度不同的抑制作用。

FromsevenbacteriaBacilussp.NT-7,17,19,32,33,39and62,wescreenedtwobacteriaNT-19andNT-62thatproducedhigheractivexylanasesinmaizecorehemicelulosemedia.ThetwoxylanaseXE19andXE62weretentativelypurifiedandtheirpropertieswerestudied.XE19andXE62showedthehighestactivitiesat50℃and60℃respectively.TheMichanelconstantofXE19andXE62was3.70mg/mLand3.76mg/mLrespectively.TheirvaluesofVmaxwere486μg/(mL·min)and445μg/(mL·min),5mmol/LheavymetalionsofAg+andHg2+showedcompletelyinhibitoryefectsonXE19andXE62,whileothermetalionsandsomeorganicreagentsdemonstrateddiferentlyinhibitoryefectsonthesetwoenzymes,theirinhibitoryratiosvariedfrom0to40%.