Potential application of two bacterial strains for bioremediation of environmental pollutants

QUEVEDO MDEL R; PAISIO CE; GONZALEZ PS; MEDINA MI; AGOSTINI E.

Mar del Plata

Congreso; VIII Congreso Argentino de Microbiologia general SAMIGE; 2012

SAMIGE

The composition of urban and industrial effluents is usually complex, including the presence of organic compounds, such as phenols and their derivatives, and inorganic compounds, for instance some metals. Remediation of these contaminants can be carried out by bacteria adapted to grow in polluted environments. In this sense, Acinetobacter sp. RTE1.4 and Rhodococcus sp. CS1 strains have shown a high potential to degrade phenol. However, their potential to bioremediate other contaminants, as well as their antibiotic resistance, are unknown. Therefore, the aims of this work were a) to determine their capability to tolerate some harmful metals; b) to evaluate their sensitivities to different antibiotics and c) to establish the ability of these bacteria to tolerate and degrade methylated and chlorinated phenols. Tolerance to metals and metalloids was evaluated in Petri dishes containing TY agar medium supplemented with several compounds (Co, Zn, Cu, Hg, Cd, Mn, Ni, Cr and As). After 7 days, the strains showed variable tolerance and Rhodococcus sp. CS1 generally tolerated higher concentrations than Acinetobacter sp. RTE1.4. Antibiotic resistant strains are not desirable for bioremediation applications due to their high ecological risk. Therefore, to determine the susceptibility of both microorganisms to antimicrobial agents, the disc agar-diffusion method was used. Acinetobacter sp. RTE1.4 and Rhodococcus sp. CS1 showed high sensitivity to the majority of antibiotics assayed. Phenolic compounds tolerance was evaluated using 2-metoxyphenol, 4-chlorophenol (4-CP), 2,4 dichlorophenol (2,4-DCP), and pentachlorophenol (PCP). The maximum tolerated concentration in TY medium, varied between 10 and 2000 mg/L for all contaminants. However, these tolerances were lower in MM. When phenolic compounds degradation assays were carried out in Erlenmeyers flask, using MM supplemented with different phenolic compounds, it could be observed that Acinetobacter sp. RTE1.4 degraded 2-metoxyphenol in concentrations between 100 and 1000 mg/L after 7 and 16 days, respectively whereas Rhodococcus sp. CS1 was able to degrade the same concentrations of 2-metoxyphenol after 8 and 16 days and 2,4-DCP (25-50 mg/L) after 9 days. In conclusion, these bacterial strains would be suitable for bioremediation processes of polluted environments with complex composition.