Uso de resíduos da rizicultura como fonte energética para obtenção de óleo microbiano a partir de leveduras Amazônicas

Abstract

The search for alternatives that can meet the demand for vegetable oils is receiving considerable attention from scientists. This premise associated with the use of waste from the agricultural sector has been considered, as the needs to protect the environment are issues that have strengthened the practice of sustainability in the industrial sphere. In view of this, the present research aimed to address three main objectives: (i) to evaluate the possibility of using rice husks from rice processing in the state of Roraima on an industrial scale, (ii) to establish optimal conditions for the use of rice husks to obtain fermentable sugars and (iii) to evaluate the potential of microbial oil production by wild yeasts isolated from roraimensi soils. To this end, a qualitative and quantitative research was initially conducted regarding rice production and processing in Roraima, and then the husks provided by four processors located in the Industrial District of Boa Vista/RR were tested by acid and enzymatic hydrolysis by experimental design. Finally, the yeasts were tested for intracellular lipid accumulation in conventional and alternative media using hydrolysates obtained in acidic and enzymatic conditions, in independent tests, and thus evaluated the composition of fatty acids present to indicate the potential of use of oils produced by microorganisms. All laboratory tests were performed in triplicate and subjected to statistical analysis. The results indicate that the volume of husks generated in rice processing in Roraima can be used in the development of industrial scale products, thus adding value to the residue. It was possible to establish protocols for the use of peels for fermentative purposes, especially in the area of microbiology. Under conventional conditions, yeasts from wild strains of genus Yarrowia accumulated intracellular lipids with yield similar to the lipid yield of oil yeasts. One strain of Rhodotorula mucilaginosa produced arachidonic acid (C20:4), a fatty acid of medical interest, using non-optimized protocols. Under alternative conditions, the use of rice husk enzymatic hydrolyzate as substrate showed results close to the use of glucose. It was concluded that new yeast strains showed the ability to produce considerable amounts of lipids, with fatty acid composition applicable to biodiesel production, medical and cosmetic industry, and that Roraima has potential for the development of products made with rice residues.