Pollution has become along the years a serious problem, difficult to solve. Developing of the industry was lead to a rising of wastes quantities, those has been accumulated in air, water and soil, when the raw resources are fewer and fewer. Classical wastes contain a large variety of pollutant but the heavy metals, toxic for human and also for environment represent a important part. In present is wide accepted idea of using biotechnology and microbiological meaning for clearing pollution of certain ecosystems from an-organics compound of heavy metals type. This involves certain phenomenon’s, being trans-location, such bioremediation, being biological modification of those metals for forming compounds less toxics or with low mobility. Recovering of heavy metals from solution can be achieved using two big group of technique, which resides by involving of electrochemical reaction. In parallel with electrochemical treatment (electrolyses, electrodeposition, electrodialysis, electrocoagulation) exist physicochemicals based on chemical precipitation, cementation and absorption on ion exchange resins, osmoses and sticking metals to biomass. This last technique can resides by bio-absorption of metallic ions on biological surfaces dead or alive, by intercellular accumulation (living biomass) or by bio-precipitation. For studies regarding evaluation of retaining capabilities by microorganisms, presented in this work, was used two strain of  bacteria’s Tf DSM583 and Tf BRGM  and 3 growing mediums: 9K, 9KM si 9Opt. Was used standard solution of uSO 4 , ZnSO 4 , CdSO 4 , CrSO 4 with a concentration  of 10 -3 M. Thiobacillus ferrooxidans, an acidophilic, aerobic, chemolithoautotrophic, gram-negative bacterium, shows a high, natural level of resistance to heavy metals. Microbial growth has been estimated by the measurement of bacterial metabolism characterized by ferrous iron oxidation. This bacterial oxidation is characterized by the Fe 2+ / (Fe 2+ + Fe 3+ ) ration. Fe 2+ concentration has been determined by colorimetric dosing of iron on a probe (10μl) by the phenanthroline method. Quantities of metallic ions recovered by bacteria  Thiobacillus ferrooxidans was determined by polarographic technique  for ions of  Zn (II) , Cd (II) , Cu (II) and by colorimetric technique for Cr (VI) .

heavy metals, Thiobacillus ferrooxidans, strain, biomass

Presentation: oral