Prospecção bioquímica da biomassa global da cianobactéria tóxica Microcystis aeruginosa BB005

Abstract

Cyanobacteria are microorganisms able to produce substances with high biological and biotechnological potential. These substances may cause disorders because of the toxins or may be composed by beneficial substances such as carotenoids, lipids and enzymes of technological interest. Hence, the scope of the current research was centered in the toxicity evaluation or prospect the substances from the Microcystis aeruginosa cyanobacterium biomass – BB 005. Daphnia magna was used in the toxicity bioassays and the cyanobacterium dry biomass was characterized by the transesterified lipids analysis, carotenoid determination, electrophoretic profile for proteins and acid hydrolysis of polysaccharides. The foam fractionation methodology was performed to separate the phycocyanin pigment and enzymes (e.g. alkaline phosphatase and lipase), using the supernatant from a liquid culture of the cyanobacterium. Although it was possible to quantify the production of toxins by BB005 strain, the ecotoxicological tests have no establish a correlation between toxin concentration and the immobility of organism bodies.The methyl esters profile in which there was a large amount of PUFAs (ω-fatty acids) with 25% of linolenates. The carotenoid content found during the lipids transesterificaction, expressed as β – carotene, was 6.6 mg/g of dry mass. The electrophoresis indicated at least 15 distinct bands of proteins and the chromatographic profile from the native polymeric carbohydrates indicated higher concentration of monosaccharide glucose and a glucose disaccharide, possible maltose. Proteins separation through foaming showed a direct correlation between the nitrogen flow and the collected foam. The phycocianin enrichment factor was high, 41.69, at a 20 mL/min N 2 flow. While in the case of alkaline phosphatase the best result was attained in the 120 mL/min of N2 flow which lead to enrichment and purification factors equal to 5.25 and 2.85 respectively. Therefore, this research has demonstrated the importance of the investigation on compounds from the M. aeruginosa entire biomass, especially the methyl esters from less common and highly insaturated fatty acids, an expressive content of carotenoids and, furthermore, the separation of phycobillin and key- enzymes for biochemical processes, that were feasibly and primarily demonstrated in this experiment by the use of foaming procedure.