Rizzatti Ana C S, Sandrim Valéria C, Jorge João A, Terenzi Héctor F, Polizeli Maria de Lourdes T M
Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes 3900, SP 14040-901, Ribeirão Preto, Brazil.
J Ind Microbiol Biotechnol. 2004 Feb;31(2):88-93. doi: 10.1007/s10295-004-0120-2. Epub 2004 Feb 6.
This study reports on the effects of growth temperature on the secretion and some properties of the xylanase and beta-xylosidase activities produced by a thermotolerant Aspergillus phoenicis. Marked differences were observed when the organism was grown on xylan-supplemented medium at 25 degrees C or 42 degrees C. Production of xylanolytic enzymes reached maximum levels after 72 h of growth at 42 degrees C; and levels were three- to five-fold higher than at 25 degrees C. Secretion of xylanase and beta-xylosidase was also strongly stimulated at the higher temperature. The optimal temperature was 85 degrees C for extracellular and 90 degrees C for intracellular beta-xylosidase activity, independent of the growth temperature. The optimum temperature for extracellular xylanase increased from 50 degrees C to 55 degrees C when the fungus was cultivated at 42 degrees C. At the higher temperature, the xylanolytic enzymes produced by A. phoenicis showed increased thermostability, with changes in the profiles of pH optima. The chromatographic profiles were distinct when samples obtained from cultures grown at different temperatures were eluted from DEAE-cellulose and Biogel P-60 columns.
本研究报道了生长温度对耐热性产黄青霉所产生的木聚糖酶和β-木糖苷酶活性的分泌及某些特性的影响。当该生物体在补充了木聚糖的培养基上于25℃或42℃培养时，观察到了显著差异。在42℃生长72小时后，木聚糖分解酶的产量达到最高水平；其产量比在25℃时高3至5倍。在较高温度下，木聚糖酶和β-木糖苷酶的分泌也受到强烈刺激。细胞外β-木糖苷酶活性的最适温度为85℃，细胞内β-木糖苷酶活性的最适温度为90℃，与生长温度无关。当真菌在42℃培养时，细胞外木聚糖酶的最适温度从50℃升高到55℃。在较高温度下，产黄青霉产生的木聚糖分解酶表现出更高的热稳定性，同时最适pH值曲线也发生了变化。当从在不同温度下培养的培养物中获得的样品在DEAE-纤维素柱和Biogel P-60柱上洗脱时，色谱图谱是不同的。
