Efluente da agroindústria do caju e óleo vegetal residual como matérias-primas para produção de biossurfactantes por bactérias de origem marinha

Abstract

Biosurfactants are tensoative compounds produced by microorganisms that have the ability to solubilize substances with different polarities. These compounds can be produced from different substrates and can be applied in different industrial areas. Thus, the aim of this research was to investigate the potential of marine bacteria to produce biosurfactants using effluent from processing of cashew nut (CNE) and residual vegetable oil as a carbon source. Twenty bacterial strains from the bacteriological collection of the Laboratory of Fish and Environmental Microbiology (LAMAP) were tested. The strains were identified by 16S rRNA sequencing. Hemolytic activity and rhamnolipids production were performed as an indicative of biosurfactant biosynthesis. Then, fermentations were realized using both substrates and the metabolites produced were submitted to the following tests: droplet collapse, emulsion index, emulsification activity and antimicrobial activity. The samples that showed the best results were submitted to the ecotoxicological test using cucumber seeds (Cucumis sativus L.) as indicator organism. The strains were identified as species from the genus: Pseudomonas, Bacillus, Staphylococcus, Vibrio, Zobelella, Oceanimonas e Brachybacterium. Of the 20 strains tested, 65% showed hemolytic activity while 40% produced rhamnolipids. From the metabolization of the agroindustrial effluent and the residual oil, respectively, 90% and 70% of bacterial strains showed activity in drop collapse, while 60% and 20% produced emulsions with good quality and stability. In addition, 50% of the metabolites produced from CNE and 5% from residual oil showed antimicrobial activity against standard strain Staphylococcus aureus (ATCC 25923). The metabolites produced with both substrates showed toxic effects against cucumber seeds. These results showed the potential to produce good quality biosurfactant compounds from pollutant residues. However, a better characterization of these bioproducts, isolation and evaluation of their toxic effects on the environment is necessary.