Produção e caracterização de bioemulsificantes produzidos por fungos filamentosos isolados de um aterro de resíduos de petróleo

Abstract

Emulsifiers are present in a wide variety of products and industrial processes and are mostly petroleum-based. Bioemulsifiers, on the other hand, are microbial polymers that offer superior performance and lower environmental impact, and are able to replace their synthetic counterparts. Among the producing microorganisms, bacteria and yeasts are the most studied, while few bioemulsifiers produced by filamentous fungi are known. In view of this, the objective of this work was to evaluate the production of bioemulsifiers by filamentous fungi isolated from an oil production waste landfill. Nineteen fungal isolates were studied, which were cultivated in mineral medium containing motor oil and were tested for the presence of bioemulsifiers using surface tension, diesel oil dispersion and motor oil emulsification tests. Then, two promising isolates were subjected to extraction of bioemulsifiers using the ethanolic precipitation method. The bioemulsifiers extracts were characterized with respect to their emulsifying activity under different conditions, and with respect to their chemical composition by the techniques of double diffusion on agar, thin layer chromatography and Fourier transform infrared spectroscopy. All isolates produced bioemulsifiers using motor oil as substrate and eighteen of them emulsified motor oil with E24 > 90% and formed stable emulsions for up to 3 months. The bioemulsifier extracts from Aspergillus flavus A85b and Trichoderma koningii A96b isolates showed efficiency in the emulsification process under conditions of high salinity (up to 30% NaCl) and temperature (121 ºC). The bioemulsifier extract from A. flavus A85b efficiently emulsified crude, engine and diesel oils, while the bioemulsifier extract from T. koningii A96b formed stable emulsions with crude and engine oils. It was also determined that the tested bioemulsifiers form stable emulsions at a concentration of 50μg.mL-1and present anionic nature and are constituted by fatty acids, carbohydrates and proteins in their composition. Due to the data collected, the bioemulsifiers produced by Aspergillus flavus A85b and Trichoderma koningii A96b have great potential for use in the oil industry and in bioremediation events.