Microrganismos degradadores de petróleo isolados de ambientes aquáticos do entorno da Base Petrolífera de Urucu, Coari, Amazonas-Brasil

Abstract

Oil has a non-renewable fossil origin, and still represents the largest source of energy today. Hydrocarbons constituting the complex petroleum blend, such as HPA's, pose a threat to human populations, animals and the environment as they are extremely toxic, mutagenic and carcinogenic xenobiotics. The process of removing oil and by-products from polluted environments requires speed, efficiency, low toxicity and low costs. In this sense, different approaches have been used with the purpose of recovering areas impacted with oil. The use of degrading microorganisms in the recovery of impacted environments has been shown to be an effective method, by aggregating ideal conditions. This work aimed to isolate, select and characterize, petroleum degrading microorganisms, natives from aquatic environments located near the Urucu Petroleum Base, Coari, Amazonas-Brazil. For isolation of the microorganisms, water samples were enriched in BH broth with petroleum, and then plated on BH agar plus 1% petroleum as the sole carbon source. The microbial isolates were submitted to the qualitative and quantitative biodegradation test with redox indicator 2,6 dichlorophenol indophenol - DCPIP. The characterization of the strains with degradation potential was performed by sequencing the 16S and 18S gene regions for bacteria and yeast, respectively. The rate of biodegradation was obtained by gas chromatography coupled to GC/MS mass spectrometry. The antimicrobial susceptibility test was performed. Three lines with potential to degrade oil were selected by means of the qualitative test with DCPIP, which discolored the medium plus oil in the maximum time of 16 hours. Two bacterial strains were identified as belonging to the species Serratia marcescens and Bacillus toyonensis, and a yeast strain as Candida mesorugosa. In the quantitative assay with DCPIP, the bacterial species S. marcescens AMS212 reduced the DCPIP concentration to 13.08 mg.L-1 in 48 hours and the B. toyonensis AM07 species was able to reduce the concentration of DCPIP to 7.23 mg.L-1 in 72 hours. In the susceptibility test, S. marcescens presented multiple resistance to four different antibiotics. The species C. mesorugosa AM15 degraded 79.4% of HPA's. The results obtained in the present study demonstrated the ability of the isolates to degrade oil and derivatives, suggesting their use in future projects aiming at the recovery of impacted areas with these xenobiotics.