Produção biotecnológica de poliésteres biodegradáveis com emprego de cianobactérias marinhas

Abstract

Plastics are essential raw materials to produce final goods that are fundamental in modern society. Their use has revolutionized practically all sectors of human activity. However, the disposal of plastic materials and the use of non-renewable raw materials constitute a major environmental liability, making it relevant to search for new plastic alternatives. Polyhydroxyalkanoates (PHA), biosynthesized by microorganisms in response to environmental stresses, are an environmentally compatible alternative for the industrial production of biopolymers (= biodegradable plastics). This study performed the bioprospecting of cyanobacteria isolated from microbial mats found in the crystallizers of salt marshes in the Cabo Frio, Rio de Janeiro, for the search of PHA producers. The unialgal strains were morphologically and molecularly identified using the 16S rRNA regions, being mostly classified in the genus Euhalothece and identified as Euhalothece sp.. In order to expand the scope of bioprospecting, an additional set of 12 other strains of cyanobacteria belonging to the genera Arthrospira, Spirulina, Leptolyngbya, Synechocystis and Synechococcus, obtained from biological collections in Brazil, were evaluated. The identification of PHA producers was performed by molecular detection of PHA biosynthetic genes and fluorescence microscopy. The Arthrospira platensis strain BMAK 159, from a biological collection, was identified as a PHA producer when cultivated and induced to accumulate this polymer using acetate. The polymer formed was extracted and purified, and the global yield of PHA was 1% (w/w), a typical value observed for other strains of the same species. The monomeric composition and purity of the material were verified using gas chromatography, confirming the composition of poly-3-hydroxybutyrate (PHB) for the induced polymer. The present study constitutes an innovative approach in Brazil aiming at the search for environmentally compatible polymers of wide use in society.