Amaya-Delgado L, Vega-Estrada J, Flores-Cotera L B, Dendooven L, Hidalgo-Lara M E, Montes-Horcasitas M C
Department of Biotechnology and Bioengineering, CINVESTAV, San Pedro Zacatenco, México DF, Mexico.
Appl Microbiol Biotechnol. 2006 Apr;70(4):477-81. doi: 10.1007/s00253-005-0096-5. Epub 2005 Jul 30.
The effect of cell density on xylanolytic activity and productivity of Cellulomonas flavigena was evaluated under two different culturing conditions: fed-batch culture with discontinuous feed of sugar cane bagasse (SCB; condition 1) and glycerol fed-batch culture followed by addition of SBC as xylanases inducer (condition 2). The enzymatic profile of xylanases was similar in both systems, regardless of the initial cell density at time of induction. However, the xylanolytic activity changed with initial cell density at the time of induction (condition 2). The maximum volumetric xylanase activity increased with increased initial cell density from 4 to 34 g l(-1) but decreased above this value. The largest total volumetric xylanase productivity under condition 2 (1.3 IU ml(-1) h(-1)) was significantly greater compared to condition 1 (maximum 0.6 IU ml(-1) h(-1)). Consequently, induction of xylanase activity by SCB after growing of C. flavigena on glycerol at intermediate cell density can be a feasible alternative to improve activity and productivity of xylanolytic enzymes.
以甘蔗渣（SCB）为底物进行间歇补料培养（条件1），以及甘油补料分批培养后添加SBC作为木聚糖酶诱导剂（条件2）。无论诱导时的初始细胞密度如何，两种系统中木聚糖酶的酶谱相似。然而，诱导时的木聚糖酶活性随初始细胞密度而变化（条件2）。最大体积木聚糖酶活性随着初始细胞密度从4 g l(-1)增加到34 g l(-1)而增加，但超过该值后则下降。与条件1（最大0.6 IU ml(-1) h(-1)）相比，条件2下最大的总体积木聚糖酶生产力（1.3 IU ml(-1) h(-1)）显著更高。因此，在中等细胞密度下，黄纤维单胞菌在甘油上生长后用SCB诱导木聚糖酶活性可能是提高木聚糖分解酶活性和生产力的可行替代方法。
