The Preparation Of Microcystins-Degrading Enzyme Powder And Its Enzyme Immobilization

In recent years,with the increasing of human activities,the level of eutrophication of water in various parts of our country has become more and more serious,causing a frequent explosion of cyanobacteria.The microcystin released from the cyanobacteria may pollute the water,aquatic products,algae products and other coproduct.It's also a serious threat to the safety of drinking water and foods.There are many ways to solve the problem of microcystins pollution.Considering the advantages of enzyme,such as speci-ficity and high efficiency,it is one of the best methods to effectively degrade micro-cystins,thus making it widely concerned.In the early research,we have already obtained the microcystins degrading enzyme(MCDE).But the enzyme we got is liquid,which is bad for preservation,transport,applications and so on.In this paper,the enzymatic pow-der and immobilized MCDE were preparaed to improve the properties of the MCDE.1.The preparation of MCDE powderWe prepared MCDE powder by lyophilization,explored and optimized the key ly-ophilized conditions(pre-freezing temperature,pre-freezing time,lyophilized volume and the time of drying)and the protective agents(saccharides,salts and proteins).a).Lyophilized conditions:the optimal pre-freezing temperature was-20?;the optimal pre-freezing time was 4 h;the optimal lyophilized volume was 5 mL(the lyophi-lized container is penicillin bottle of 25 mL)and the optimal time of drying was 8 h.The activity recovery rate of MCDE powder reached a relatively high level,58.27%.b).Protective agents:we choose a few representative substances like L-monosodium glutamate,starch,BSA and trehalose as protective agents.The results showed that treha-lose was the best protective agent for MCDE.The optimal m/V of trehalose and the en-zyme solution was 1:10,while the activity recovery rate of MCDE powder was 76.24%.2.The preparation of immobilized MCDEMCDE has low stability and is sensitive to the change of temperature and pH when it is free enzyme.So we tried to immobilize MCDE in order to overcome the disad-vantages.And the result showed that:the best immobilized temperature is 37?,the best immobilized method is vibrated(100rpm)MCDE with GO for 2 h.Finally,immobilized MCDE with excellent stability and good adaptability to temperature and pH was obtained.And the activity recovery rate of immobilized MCDE was 95.29%.