Bioremediation of phenol by a bacterial strain isolated from tannery sediments

PAISIO C., , , ; TALANO M.; GONZÁLEZ P.; MEDINA M.I.,; AGOSTINI E.

Congreso; VII congreso Argentino de Microbiología General ?SAMIGE del Bicentenario.; 2011

Many industrial activities produce a large volume of pollutant wastes, generating a deleterious effect on the environment. In particular, wastewater derived from leather production may contain phenols, which are highly toxic and their degradation could be possible through bioremediation technologies. The aims of this work were: a) isolate bacterial strains, tolerant to phenol, from tannery effluents and sediments, b) select a strain with high phenol tolerance and evaluate its tolerance to other phenolic compounds, c) identify and characterize this isolate by biochemical and molecular assays, d) determinate the effect of pH, culture media composition, temperature and phenol initial concentration for its degradation, e) evaluate the ability of the strain to grow and degrade phenol in tannery effluents. Effluent and sediment samples were obtained from a tannery located in Elena (Cba. province). Some physicochemical parameters of these samples were evaluated as well as total phenol concentration, which was 17.5 mg/L. A bacterial strain, namely as CS1, showing fast growth in TY medium supplemented with 100 mg/L of phenol was selected. CS1 was characterized as a Gram positive, oxidase-negative and catalase-positive bacterium. Physiological and biochemical tests were performed in order to characterize the strain. It was identified as Rhodococcus sp. by 16S rDNA gene PCR amplification. The strain was able to grow in 1000 mg/L of phenol and guaiacol, and 500 mg/L of 2,4-dichlorophenol, whereas it was not able to tolerate pentachlorophenol, in mineral medium with these contaminants as sole carbon source. Phenol biodegradation studies were carried out in Erlenmeyer flasks with different culture media (MM1, MM2, MM3, MM9), at different pH (5-11), temperature (25-37 °C) and initial phenol concentrations (200-1000 mg/L). Bacterial biomass and phenol consumption were determined in these experiments. CS1 strain was able to remove completely 1000 mg/L of phenol in MM1 medium at 30 ± 2 °C and pH 7, as optimal conditions. Furthermore, growth and phenol degradation of CS1 strain in Erlenmeyers flask containing tannery effluents was evaluated. After 9 h of incubation, the bacterium showed tolerance to this effluent and ability to completely degrade phenols. In conclusion, Rhodococcus sp. CS1 could be an appropriate microorganism for bioremediation of tannery effluents or other environments contaminated with phenols. Área temética: Bioremediación y biocontrol