THERMOSTABLE XYLANOLYTIC ENZYMES FROM RHODOTHERMUS-MARINUS GROWN ON XYLAN
THERMOSTABLE XYLANOLYTIC ENZYMES FROM RHODOTHERMUS-MARINUS GROWN ON XYLAN
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DOI：
10.1007/bf00170430
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发表时间：
1993-10-01
影响因子：
5
通讯作者：
KRISTJANSSON, JK
中科院分区：
文献类型：
--
作者：
DAHLBERG, L;HOLST, O;KRISTJANSSON, JK
在发酵罐中培养嗜热真细菌Rhodothermus marinus，并研究诱导木聚糖分解酶的活性。对于分批培养物，发酵罐中木聚糖的生长最大比生长率为 0.43 h-1。在木聚糖上生长的细胞的最终细胞浓度为4g细胞干重(CDW)/l，相比之下，在培养基中不含木聚糖的情况下生长的细胞的最终细胞浓度为2g CDW/l。当细胞在木聚糖上培养时，至少两种木聚糖分解酶（内切-1,4-β-木聚糖酶和木聚糖1,4-β-木糖苷酶）被分泌到培养基中。在测试活性的三种纤维素分解酶中，β-葡萄糖苷酶活性在木聚糖分解酶活性范围内，而纤维素-1,4-β-纤维二糖苷酶和纤维素酶活性几乎检测不到。培养过程中内切 1,4-β-木聚糖酶活性的表达表明 R. marinus 中存在不止一种木聚糖酶。在凝胶过滤的级分中也观察到了这一点。木聚糖分解酶是热稳定的。在 90 摄氏度和 pH 7.0 下，内切 1,4-β-木聚糖酶的半衰期约为 14 小时，木聚糖 1,4-β-木糖苷酶的半衰期为 45 分钟。
The thermophilic eubacterium Rhodothermus marinus was cultivated in a fermentor and studied with respect to activities of induced xylanolytic enzymes. Growth in the fermentor on xylan occurred with a maximum specific growth rate of 0.43 h-1 for a batch culture. The final cell concentration was 4 g cell dry weight (CDW)/l for cells grown on xylan compared to 2 g CDW/l for cells grown without xylan in the cultivation medium. At least two xylanolytic enzymes, endo-1,4-beta-xylanase and xylan 1,4-beta-xylosidase, were secreted into the culture medium when cells were cultivated on xylan. Of the three cellulolytic enzymes tested for activity, beta-glucosidase activity was in the range of the xylanolytic enzyme activities whereas cellulose-1,4-beta-cellobiosidase and cellulase activities were hardly detectable. The expression of endo-1,4-beta-xylanase activities during cultivation indicates the existence of more than one xylanase in R. marinus. This is also observed in fractions from gel filtration. The xylanolytic enzymes are heat-stable. At 90-degrees-C and at pH 7.0 the half-life of the endo-1,4-beta-xylanase was about 14 h and that of xylan 1,4-beta-xylosidase was 45 min.