摘要
纤维素酶是诱导酶,理想的碳源应该既能提供菌种生长所需能量,又能诱导纤维素酶基因的高效表达。试验中分别以葡萄糖经过转糖苷反应后制备的复合糖(F)、微晶纤维素(C)以及上述两者(1∶2)的混合物(M)为里氏木霉(Trichoderma Reesei ZU-04)的碳源,在液态深层发酵条件下生产纤维素酶。对纤维素酶酶系组成的研究结果表明:F碳源诱导作用下,内切型-β-葡聚糖酶(Cx酶)和外切型-β-葡聚糖酶(C1酶)的活力在发酵初期上升很快,通常在40h左右达到峰值,此后活力呈下降趋势,而β-葡萄糖苷酶(CB酶)的活力始终较低;C碳源诱导作用下,Cx、C1和CB酶的活力上升在发酵初期比较缓慢,但持续时间长、后劲足;在采用M碳源的情况下,Cx、C1酶的初始合成速度较快,且2种酶的活力在较长时间内保持上升趋势。与F和C碳源相比,Cx酶活力分别提高了78.2%和51.9%,C1酶活力分别提高了20.6%和6.5%,但对CB酶的生产而言,M碳源略低于C碳源,F碳源最差。进一步研究了碳源对纤维素酶总活力(滤纸酶活力)的影响,结果显示:在采用F碳源的条件下,发酵6h即可检测到滤纸酶活力,在36h达到峰值1.6IU/mL,此后活力不再上升;在采用C碳源时,发酵初期酶活力上升缓慢,产酶周期较长,滤纸酶活力在144h达到峰值3.96IU/mL;而M碳源可结合两者优势,使纤维素酶活力和产率都能达到较高的水平。研究结果对于定向调控纤维素酶的酶系组成,提高纤维素酶的生产效率具有重要意义。
Cellulase can be induced by different inducers. A desirable carbon source should support the growth of microorganisms and induce the expression of cellulase genes effectively. Self-made sugar mixture obtained by transglycosylation from glucose （F carbon source）, microcrystalline cellulose （C carbon source） and the multiple carbon source （ M carbon source, mixture of F and C in the ratio 1 ： 2） were applied in the submerged fermentation of cellulase with Trichoderma Reesei ZU-04. Properties of carbon sources were found to have different effects on the cellulase components. On F carbon source, the enzyme activities of endo-13-1,4-glucanase （Cx）, exo-13-1,4-glucanase （C1） increased quickly and reached their peak value at around go h, but the activity of （-glucosidase（CB） were remained extremely low throughout the process. On C carbon source, the activities of Cx, C1 and CB grew slowly at the initial stage, but the production cycle sustained longer with the continuous increase of enzyme activities. M carbon source could both accelerate the formation rate and enhance the production sustainability of Cx and C1, Cx activities increased by 78.2% and 51.9% , and C1 activities increased by 20.6% and 6.5% compared with those produced by C and F carbon sources respectively. As to the 13-glucosidase production, the F carbon source was the worst among all, and C carbon source was better than M carbon source. The influence of different carbon sources on filter paper activities was further studied. F carbon source produced the highest filter paper activity of 1.60 IU/mL within 36 h, featured by a rapid celluase formation rate, yet unsustainable production cycle. Filter paper activity induced by C carbon source reached a maximum of 3.96 IU/mL within 144 h, yet, cellulase activity increased slowly at the initial stage and cellulase production cycle lasted longer. Combined the advantages of F and C, M carbon source could maintain both filter paper activity and productivity at relatively high levels. The results are of great significance in improvement of cellulase productivity and regulation of cellulase system.
出处
《食品与发酵工业》
CAS
CSCD
北大核心
2010年第3期1-4,共4页
Food and Fermentation Industries
基金
国家"863"项目(2007AA05Z401)
国家科技支撑计划项目(2007AA05Z401)
关键词
纤维素酶
复合糖
微晶纤维素
酶系组成
诱导合成
cellulase, sugar mixture,microcrystalline cellulose, cellulase components, synergetic induction
