Amity School of Earth and Environmental Science, Amity University Haryana, India.
School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110067, India.
Int J Biol Macromol. 2019 Jun 15;131:445-452. doi: 10.1016/j.ijbiomac.2019.03.082. Epub 2019 Mar 13.
Bacterium Bacillus sp. SS105, isolated from Free Air CO Enriched (FACE) soil was previously screened for carbonic anhydrase activity and CO sequestration. In this study, strain was selected to amplify carbonic anhydrase encoding genes. The CA genes from Bacillus sp. SS105 were found to be homologous with beta‑carbonic anhydrase (β-CA) and gamma‑carbonic anhydrase (γ-CA). Both types of CA genes was cloned in pET30b (+) and expressed in E coliBL21 (DE3) with His-tag at the N-terminus. The recombinant proteins were purified by Ni-NTA affinity chromatography. The molecular size of β-CA and γ-CA were approximately 27 kDa and 25 kDa respectively. The optimum pH and temperature were found to be 8.0 and 37 °C respectively. The Zn was enhancing the CAs enzyme activity. Anions and modulators showed inhibitory effect on CAs at specific concentration. Functional domain analysis of both CA proteins showed conserved region of respective proteins. Recombinant enzymes were used for bio-mineralization based conversion of atmospheric CO into valuable calcite. Calcite formation was evaluated with or without use of enzymes and confirmed by SEM and XRD analysis. SEM result confirmed the conversion of flower-shaped unstable form of vaterite to hexagonal cubic stable form of calcite in presence of enzymes.
从富 CO2 空气（FACE）土壤中分离出的芽孢杆菌 SS105 菌先前被筛选出具有碳酸酐酶活性和 CO2 固定能力。在这项研究中，选择了该菌株来扩增碳酸酐酶编码基因。从芽孢杆菌 SS105 中发现的 CA 基因与β-碳酸酐酶（β-CA）和γ-碳酸酐酶（γ-CA）同源。两种类型的 CA 基因均被克隆到 pET30b（+）中，并在带有 N 端 His 标签的大肠杆菌 BL21（DE3）中表达。重组蛋白通过 Ni-NTA 亲和层析进行纯化。β-CA 和 γ-CA 的分子量约为 27 kDa 和 25 kDa。最佳 pH 和温度分别为 8.0 和 37°C。Zn 增强了 CA 酶的活性。在特定浓度下，阴离子和调节剂对 CA 表现出抑制作用。两种 CA 蛋白的功能域分析显示了各自蛋白的保守区域。重组酶用于基于生物矿化的大气 CO2 转化为有价值的方解石。通过 SEM 和 XRD 分析评估了有无酶存在时的方解石形成情况。SEM 结果证实了在酶的存在下，将花状不稳定的文石转化为六方立方稳定的方解石。
