Avaliação do processo de produção de ficobiliproteínas de cianobactérias e purificação por sistemas aquosos bifásicos

Abstract

Cyanobacteria also known as algae blue green, are a group of autotrophic photosynthetic mi-croorganisms. They produce a variety of bioactive compounds, and may be metabolites like antibacterial, anticoagulant, anti-inflammatory, antiviral, antitumor and cytotoxic compounds or pigmented compounds, such as chlorophyll a, b and c, beta-carotene and phycobiliproteins (PBP). Among the pigmented compounds are the PBP, which are a set of pigmented proteins, water-soluble and fluorescent, with applications in the food industry as natural dyes and in the pharmaceutical industry as fluorescent markers in disease diagnosis. The main FBP found in cyanobacteria is phycocyanin (PC). The procurement process is based on three stages, repre-sented by cultivation, extraction and recovery / purification. The present work was a study about the production and recovery of PBP of two strains of cyanobacteria little explored in the literature, Anabaena variabilis and Nostoc sp. Different extraction methods of PBP, re-covery for Aqueous Two-Phase System (ATPS) and production of PBP by supplementation with organic carbon and nitrogen sources in addition to the basal culture medium were inves-tigated in order to increase their productivity. The ATPS was used since it is an attractive technique for biomolecules, because it has water in high concentration in both phases, being thus a compatible and non-toxic for proteins. The ATPS used was of the polyethylene glycol (PEG)-salt type, varying the molecular weight of the PEG (1500 and 4000) and the salt type (potassium phosphate, ammonium sulfate and sodium citrate) for purification, in different proportions, in order to increase the initial purity of the FBP obtained by the extraction meth-od. Results were obtained for extraction, only FC was found in both cyanobacteria, the best extractive solution being phosphate buffer pH 7.0 0.1M, the best method of extraction by freezing and thawing in ultrasonic bath obtaining the highest concentrations of FC (32.8 μg/mL and 34.6 μg/mL) and purities (0.54 and 0.59) for Nostoc sp. and Anabaena variabilis, respectively, and the best solid-liquid ratio of 0.4 g of cell/L of extractive solution, yielding 0.354 mg FC. For recovery, the best condition was ATPS PEG 1500-phosphate, in proportion (10% PEG and 15.9% salt), recovering 79.10%, partition coefficient of 6.36 and final purity of 1.34 the extract of Nostoc sp. and recovery of 82.10%, partition coefficient of 5,73 and final purity of 1.12 for the Anabaena variabilis extract. The best result for supplementation to the culture medium was 2 g/L glucose and 5 mM sodium nitrate, increasing the FC concentra-tion by up to 50% compared to the basal medium, with a yield of 48.73 μg/mL. Nostoc sp. at 14 days and 18.57 μg/mL for Anabaena variabilis at 10 days.