Asatiani Nino V, Abuladze Marina K, Kartvelishvili Tamar M, Bakradze Nugzar G, Sapojnikova Nelly A, Tsibakhashvili Nelly Ya, Tabatadze Leila V, Lejava Lia V, Asanishvili Lali L, Holman Hoi-Ying
Institute of Physics, Georgian Academy of Science, 6 Tamarashvili Street, 0177 Tbilisi, Georgia.
Curr Microbiol. 2004 Nov;49(5):321-6. doi: 10.1007/s00284-004-4351-2.
Arthrobacter species is of interest because of its high potential for bioremediation. Bacteria can detoxify chromium, by either reduction or accumulation inside the bacteria and/or absorption of chromium(VI) (CrVI) on their surface, and efflux pump. The possible pathway of Cr(VI) reduction by Arthrobacter oxydans isolated from Columbia basalt rocks at a US DOE highly contaminated site (USA) has been considered in the present study. FTIR absorption spectroscopy showed that these bacteria reduce Cr(VI). In the present study the threshold Cr(VI) nontoxic concentration (35 microg/mL) for A. oxydans growing in liquid medium was estimated. Complete uptake of this concentration was achieved in about 10 days after chromium addition into the medium. At this concentration an increase in the protein isolated from the cell wall of A. oxydans was observed. This increased protein predominated independently of the growth phase at which Cr(VI) was added. Thermal analysis was used to identify any influence of Cr(VI) on the DNP complex of A. oxydans. According to the data obtained it can be supposed that Cr(VI) reduction predominantly occurs on the bacterial surface and that cell wall represents a permeable barrier for these bacteria at the non-toxic chromium action.
节杆菌属因其在生物修复方面的巨大潜力而备受关注。细菌可以通过在菌体内还原或积累以及/或者在其表面吸附六价铬（CrVI）并借助外排泵来对铬进行解毒。本研究探讨了从美国能源部一个高度污染场地（美国）的哥伦比亚玄武岩中分离出的氧化节杆菌还原Cr(VI)的可能途径。傅里叶变换红外吸收光谱表明这些细菌能够还原Cr(VI)。在本研究中，估算了氧化节杆菌在液体培养基中生长时Cr(VI)的无毒阈值浓度（35微克/毫升）。向培养基中添加铬后，大约10天可完全摄取该浓度的铬。在此浓度下，观察到从氧化节杆菌细胞壁分离出的蛋白质有所增加。这种增加的蛋白质在添加Cr(VI)的任何生长阶段均占主导。热分析用于确定Cr(VI)对氧化节杆菌二硝基苯酚复合物的任何影响。根据所得数据可以推测，Cr(VI)的还原主要发生在细菌表面，并且在无毒铬作用下，细胞壁对这些细菌而言是一个可渗透的屏障。
