Investigação da correlação entre o potencial de biorremediação e a produção de oxidorredutases por Pseudomonas aeruginosa

Abstract

Environments contaminated by polycyclic aromatic hydrocarbons are challenges that can be minimized with the use of microorganisms with degradation potential. The objective of this work was to evaluate the degradation capacity of anthracene and pyrene by a Pseudomonas aeruginosa isolate and to correlate with laccase and manganese peroxidase activity. Three isolates of Pseudomonas aeruginosa (TGC-02, 03 and 07) and one positive control with Aspergillus niger were evaluated. The experiments were divided into two steps: screening with P. aeruginosa isolates was initially screened for emulsification and drop collapse tests. The higher hydrocarboclastic activity was observed for the TGC-02 isolate, which degraded more than 30% of the contaminants tested. Subsequently, the biodegradation assays of the anthracene and pyrene contaminants by the selected TGC-02 isolate and compared to an A. niger isolate were conducted. The assays lasted 25 days at room temperature in microcosms containing 30 mL of distilled water, contaminated with 50 mg / L of pyrene or anthracene, under static incubation. For each point of analysis, pH, biomass, cell viability, total proteins and enzymatic activity were measured. The content of the contaminants was determined by gas chromatography coupled to flame spectrometry after 25 days of the bioprocess. No specific activity was observed for laccase or manganese peroxidase in the tested isolates, and it was not possible to correlate the degradation capacity with the specific activity of these enzymes. However, when analyzing the total protein results, it was observed that during the 25 days there was an increase in the concentrations of total proteins in presence of the contaminants, especially for P. aeruginosa TGC-02. The TGC-02 and A. niger isolates cultured in the presence of the contaminants presented viability during the 20 days of the bioprocess. Discounting the abiotic losses, the positive control A. niger degraded 28.11% and 30.70% of the pyrene and anthracene, respectively. P. aeruginosa TGC-02 presented better results, reducing pyrene and anthracene in 37.83% and 33.01%, respectively. A. niger is a fungus known as a degradation agent of aromatic compounds, however, in this work P. aeruginosa proved to be more efficient in the degradation of pyrene and anthracene in the liquid medium in 25 days. The results demonstrate the potential of bioremediation of P. aeruginosa for the removal of pyrene and anthracene, apparently independent of the production of manganese peroxidase and laccase.