Abstract :

Using the two plasmids, pUC8:16 and pUC9 in the cell grown on different carbon and nitrogen sources afforded comparable levels of copper uptake by Escherichia coli. Previously, no such investigations have been made, particularly using bacterial hemoglobin (VHb), carbon and nitrogen sources. It is clear from these results that the type of either carbon or nitrogen sources control the level of the copper uptake mechanisms. In case of VHb-expressing cells, glycerol and sucrose selectively enhanced the copper uptake as compared with non-VHb-expressing cells. In the case of wild type cells, carboxylic acid (succinic acid and tri-sodium citrate) enhanced the copper uptake capacity over vgb-bearing and pUC9-bearing cells. For pUC9-bearing cells, the glucose and the rich media LB showed the highest copper uptake. In case of inorganic nitrogen sources, using Ammonium chloride, the level of copper was highest in the E. coli:pUC9 > E. coli:pUC8:16 > E. coli (wild type). Whereas with ammonium nitrate, the copper uptake was equal in the three strains. In case of organic nitrogen source (Trypton), the copper uptake was the following pUC9-bearing cells > wild type > VHb-expressing cells. Also, irrespective of the strain, carbon and nitrogen sources used, the three types of copper behave similarly. The optimum growth biomass and copper uptake was maximally obtained at the temperature 37 and 20±2°C, respectively indicating that the copper uptake is at least partially metabolically dependent process. Only at the hypoxic conditions, VHb enhanced the growth of the host cells as compared with the non-vgb strains.

https://scialert.net/fulltext/?doi=pjbs.2006.2022.2031