水泥基材料中Ca^(2+)对矿化微生物的碳酸酐酶产量、活性和矿化的影响

Effects of Ca^(2+)in Cement-based Materials on the Yield,Activity and Mineralization of Carbonic Anhydrase of Mineralized Microorganism

本工作针对一种适用于水泥基材料的耐碱矿化微生物,研究了水泥基材料中Ca^(2+)浓度变化(0~5 mmol/L)对矿化微生物的产酶量、碳酸酐酶活性以及诱导CaCO_(3)矿化能力的影响。对分离纯化不同Ca^(2+)浓度菌液中的碳酸酐酶进行酶产量测定,并通过测定矿化微生物的细菌生长曲线和单菌产酶量分析Ca^(2+)浓度对其的影响机理;基于酯酶法测定不同Ca^(2+)浓度下碳酸酐酶的活性,并利用FTIR测定官能团,分析二级结构变化和氢键变化,进而得到Ca^(2+)浓度对碳酸酐酶活性的影响机理;最后基于热重分析不同Ca^(2+)浓度溶液中矿化微生物的诱导矿化能力,并测定矿化产物晶形。试验结果表明,当Ca^(2+)浓度为2.5 mmol/L时,矿化微生物生长增殖最快,单菌产酶量最高,因此整体酶产量最高;碳酸酐酶活性在Ca^(2+)浓度为5 mmol/L时达到最大值,但Ca^(2+)会破坏碳酸酐酶结构的有序性;当Ca^(2+)浓度为5 mmol/L时,矿化微生物的诱导矿化能力最强,矿化3 d后Ca(OH)_(2)向CaCO_(3)的转化率达到82.67%,且得到的CaCO_(3)晶体形貌主要为球状或椭圆状。

Aiming at an alkali resistant mineralized microorganism suitable for cement-based materials,this work studied the effects of Ca^(2+)concentration change(0—5 mmol/L)in cement-based materials on the enzyme production,carbonic anhydrase activity and the ability to induce CaCO_(3)mineralization of mineralized microorganisms.The carbonic anhydrase in bacterial solution with different Ca^(2+)concentration was isolated and purified,and the enzyme yield was determined.The influence mechanism of Ca^(2+)was analyzed by measuring the OD 600 curve of mineralized microorganism and the enzyme yield of single bacterium;the carbonic anhydrase activity under different Ca^(2+)concentrations was determined by the esterase method,and the functional groups were determined by FTIR.The changes of secondary structure and hydrogen bond were analyzed,and the influence mechanism on the activity was obtained;finally,the mineralization inducing ability of mineralizing microorganisms in different Ca^(2+)concentration solutions was analyzed based on TG,and the crystal form of mineralized products was determined.The test results show that when the concentration of Ca^(2+)was 2.5 mmol/L,the mineralized microorganisms grew and proliferated the fastest and the enzyme yield of a single bacterium was also the highest,so the overall enzyme production was the highest.The activity of anhydrase reached the maximum when the concentration of Ca^(2+)was 5 mmol/L,but Ca^(2+)would destroy the structural of carbonic anhydrase;the mineralizing microorganism has the strongest ability to induce mineralization in 5 mmol/L.After 3 d of mineralization,the conversion rate of Ca(OH)_(2)to CaCO_(3)reached 82.67%,and the morphology of CaCO_(3)crystal was mainly spherical or elliptical.