- 期刊
Enhanced Decolorization of Azo Dyes with Selected Mutants of Escherichia coil
以篩選之大腸桿菌突變株進行高效率偶氮染料褪色
摘要
本研究之目的在於開發具高效率偶氮染料褪色能力之大腸桿菌突變株。首先以紫外線照射的方式進行隨機突變，接著將突變菌種馴養在含偶氮染料(Reactive Black B和Reactive Red 22)之基質中進行篩選。由眾多突變菌種中篩選出兩株對偶氮染料具高褪色效率且穩定性佳之突變菌株，命名為大腸桿菌UVT1和大腸桿菌UV68。該突變菌株對偶氮染料的比褪色速率可比原始菌株提高3倍，且其降解50%偶氮染料所需要時間比原始菌株縮短達7倍以上。本研究並探討染料濃度、葡萄糖濃度和環境的條件（例如溫度、轉速等）對兩株突變菌種褪色能力之影響。結果顯示，突變菌種UVT1在高染料濃度下具有較好的染料去除能力且較不易受氧氣的抑制，且UVT1菌株的褪色能力明顯優於另一株突變菌株UV68。實驗結果並證實此兩突變菌株對染料之褪色現象乃源於酵素活性，而非肇因於與代謝無關的生物吸附行為。以Monod-type model進行褪色動力學分析，發現紫外線突變菌株對染料褪色能力之促進可能由於菌種對染料基質接觸與利用效率之增加。而葡萄糖對染料褪色之抑制現象，則可能由於酸性代謝物之形成而造成pH值遞減所致。
關鍵字
無資料並列摘要
An Escherichia colt strain was mutated by random mutagenesis via exposure to UV light. The resulting mutants were acclimated in azo-dye-containing media to select for highly efficient and stable decolorization activity on to azo dyes (Reactive Black B and Reactive Red 22). Two mutant strains (namely, E. coli UVT1 and E. coli UV68) were identified and their specific decolorization rates for the azo dyes were up to 3-fold faster than that of the mother strain. The mutant strains also displayed up to 7-fold increase in total decolorization efficiency, which is represented by the time required for 50% color removal. Decolorization characteristics of the mutants were investigated in terms of their dependence on dye concentration, glucose concentration, and environmental conditions (e.g., temperature, agitation rate, etc.) The mutant E. colt UVT1 exhibited optimal color removal activity under high dye concentrations and was less sensitive to oxygen inhibition. The decolorization performance of the UVT1 strain was superior to that of the other mutant strain UV68. Decolorization by the mutants was shown to be an enzymatic event, while contribution of metabolism-independent biosorption to the color removal was negligible. Kinetic analysis by Monod-type model suggests that the mutation may lead to an enhanced accessibility of the dye substrate to the bacterial decolorizer. The inhibitory effect of glucose on decolorization was observed and seemed to be closely associated with sharp pH decreases due to formation of acidic metabolites while using glucose for cell growth and decolorization.