Biorremediação de ambientes aquáticos contaminados por resíduos de petróleo: um estudo com bactérias isoladas de eichornia crassipes na Amazônia

Abstract

Biodiversity is a fundamental element for biotechnology development, especially in Amazon because its incontestable potential. One aspect of high interest is the search for management mechanisms that can promote environmental quality, ensuring the maintenance of natural features of ecosystems. In this context is located an important biotechnology tool that is the bioremediation of environments contaminated with toxic and recalcitrant compounds. Thus the exploration of microrganisms for use in these processes has been a challenge. This work presents a study about sample of bacterial community associated with the aquatic macrophyte Eichornia crassipes, assessing their potential for biodegradation of petroleum hydrocarbons. Selective isolations and preliminary identification of some of the isolates by region of 16S ribosomal DNA sequences to compare with the Gen Bank were done. The potential to produce biossurfactantes was evaluated by the activity of bacteria in emulsification. The growth of strains was assessed by mineral medium with hydrocarbons mixing and mineral medium with crude oil. The rate of toxicity was evaluated in mixture of hydrocarbon extracts with the five strains that showed the best growth. Considering the results of these first tests, it was produced a consortium with bacteria more efficient. It was evaluated the degradation of aliphatic and aromatic hydrocarbons in experiment containing Amazon river water, using the techniques of bioaugmentation and biostimulation. There were isolated 71 bacteria, 42 epiphytic and 29 endophytic. The preliminary identification revealed the predominance of the genera Acinetobacter, Pseudomonas, Bacillus and Stenotrophomonas. There was more bacterial growth in medium with crude oil, especially the strain Stenotrophomonas sp,. reaching around 13.4 x106 UFCs / mL. The methods used in bacterial growth indicated the degradation of petroleum hydrocarbons, whereas they were the sole source of carbon. Highlighted in the production of biossurfactantes the strains Methylobacterium sp and Stenotrophomonas radiotolerans, with better results in the medium with oil. The indices of toxicity showed better results in extracts of bacterial growth compared to control extracts. The strains that showed better results were used for consortium production: Stenotrophomonas sp., Uncultured Klebsiella sp., Enterobacter sp., Methylobacterium radiotolerans and Acinetobacter baumannii. In the experimental design with the consortium, the results showed that the main effect of all parameters studied influenced the degradation of the hydrocarbons studied, however the addition of the consortium was the most important factor in this decline, demonstrating the potential of these strains for use in future processes of bioremediation.