Environmental Biotechnology Division, National Environmental Engineering Research Institute, Nehru Marg, Nagpur 440020, India.
J Hazard Mater. 2010 May 15;177(1-3):481-6. doi: 10.1016/j.jhazmat.2009.12.058. Epub 2009 Dec 21.
Present study describes isolation of a multiple metal-resistant Arthrobacter ramosus strain from mercuric salt-contaminated soil. The isolate was found to resist and bioaccumulate several metals, such as cadmium, cobalt, zinc, chromium and mercury. Maximum tolerated concentrations for above metals were found to be 37, 525, 348, 1530 and 369 microM, respectively. The isolate could also reduce and detoxify redox-active metals like chromium and mercury, indicating that it has great potential in bioremediation of heavy metal-contaminated sites. Chromate reductase and mercuric reductase (MerA) activities in protein extract of the culture were found to be 2.3 and 0.17 units mg(-1) protein, respectively. MerA enzyme was isolated from the culture by (NH(4))(2)SO(4) precipitation followed by dye affinity chromatography and its identity was confirmed by nano-LC-MS/MS. Its monomeric molecular weight, and optimum pH and temperature were 57kDa, 7.4 and 55 degrees C, respectively. Thus, the enzyme was mildly thermophilic as compared to other MerA enzymes. K(m) and V(max) of the enzyme were 16.9 microM HgCl(2) and 6.2 micromol min(-1)mg(-1) enzyme, respectively. The enzyme was found to be NADPH-specific. To our knowledge this is the first report on characterization of MerA enzyme from an Arthrobacter sp.
本研究描述了一株耐多种金属的节杆菌（Arthrobacter ramosus）从含汞盐污染土壤中的分离。该分离株被发现能够抵抗和生物累积多种金属，如镉、钴、锌、铬和汞。对于上述金属，最大耐受浓度分别为 37、525、348、1530 和 369 μM。该分离株还可以还原和解毒氧化还原活性金属，如铬和汞，这表明它在重金属污染场地的生物修复方面具有巨大的潜力。在培养物的蛋白质提取物中发现了铬酸盐还原酶和汞还原酶（MerA）的活性，分别为 2.3 和 0.17 个单位 mg(-1) 蛋白质。MerA 酶是通过（NH(4))(2)SO(4)沉淀、染料亲和层析从培养物中分离出来的，并通过纳升液相色谱-串联质谱（nano-LC-MS/MS）确认了其身份。其单体分子量、最适 pH 和温度分别为 57kDa、7.4 和 55°C。因此，与其他 MerA 酶相比，该酶为轻度嗜热酶。该酶的 K(m)和 V(max)分别为 16.9 μM HgCl(2)和 6.2 微摩尔 min(-1)mg(-1)酶。该酶被发现是 NADPH 特异性的。据我们所知，这是首次从节杆菌属（Arthrobacter sp.）中对 MerA 酶进行表征的报道。
