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DATE: 14/02/2023
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Isolation and selection of pigment-producing cyanobacteria.


Phycoerythrin. Phycocyanin. Atlantic Forest. Carotenoids. Scytonemins.

PAGES: 112
AREA: Ciências Ambientais

Cyanobacteria have in their composition several pigments (e. g. carotenoids, phycobiliproteins, and photoprotective compounds) with many applications in the food, cosmetic and pharmaceutical industries. These microorganisms can be found in the most diverse environments. The Atlantic Forest of southern Bahia presents conditions to support biodiversity with the potential for producing pigments not yet characterized. Thus, the present research aimed to select cyanobacteria isolated from reservoirs located in preserved areas of the Atlantic Forest, based on biomass and pigment production. To this end, after access registration at SISGEN, isolation was carried out by glass capillarity or spread-plate in BG-11 and ASM-1 medium from three reservoirs in a preserved area of Atlantic Forest. The isolated strains were identified at the genus level based on morphology and cultivated for 14 days in 300 mL of the respective media, under constant lighting of 15 µmol·m-2·s-1, plus UVA/UVB lighting for 2 h·d-1. Growth was monitored by spectrophotometric quantification of chlorophyll (90% ethanol extraction) every two days. At the end of the cultivation, the pigments were extracted with solvents (ethyl acetate for nonpolar and PBS for phycobiliproteins) and detected via spectrophotometry. The selection was based on pigment concentration and biomass accumulation. The selected isolates were cultivated in a bubble column photobioreactor, with previously characterized hydrodynamics, and the volumetric productivity of phycobiliprotein and the pigment content were determined. Henceforth, the influence of light color and light intensity on the production of phycobiliproteins of the isolated strains was evaluated, in addition to purification by ion exchange FPLC and partial characterization by SDS-PAGE. In total, 17 cyanobacteria belonging to the orders Synechococcales (02) and Oscillatoriales (15), distributed in nine genera, were isolated. In all strains, carotenoids (maximum of 0.387 mg·g-1) and phycobiliproteins (maximum of 84.64 mg·g-1) were detected, while scytonemins were detected in 4 strains in concentrations below 0.1 mg·g-1. Two strains were selected: Phormidesmis sp. F2 and Pantanalinema sp. B1. The F2 strain showed accumulation of dry biomass of 1.35 ± 0.08 g·L-1, 66.71 ± 2.78 mg·g-1 of phycocyanin and 17.93 ± 2.05 mg·g-1 of allophycocyanin. In Pantanalinema sp. B1, a maximum concentration of phycoerythrin of 48.88 ± 5.00 mg·g-1 was detected. In photobioreactor, Phormidesmis sp. F2 presented biomass and phycocyanin productivity of 0.14 g·L-1·d-1 and 8.62 ± 0.34 mgPC·L-1·d-1, respectively. Pantanalinema sp. B1 showed biomass and phycoerythrin productivities of 0.13 g·L-1·d-1 and 6.99 ± 0.49 mgPE·L-1·d-1, respectively. Cultivation of the B1 strain under green light and light intensity of 25 µmol·m-2·s-1 resulted in 8.30 mgPE·L-1·d-1, a value 70% higher than the same intensity under white light. For the F2 strain, the highest productivity occurred under red light and 100 µmol·m-2·s-1 (13.38 ± 0.77 mgPC·L-1·d-1), but statistically similar to when cultivated under white light at 50 µmol·m-2·s-1. The purification of phycoerythrin from B1 had a final yield of 21.35% with a purity of 3.90 and electrophoresis revealed the composition by two bands with approximately 16.5 and 17.5 kDa.

Externo à Instituição - BRUNA REHEM - IFBA
Externa à Instituição - SUZANA TELLES DA CUNHA LIMA - UFBA
Interno - 3074212 - THIAGO MAFRA BATISTA
Notícia cadastrada em: 01/02/2023 10:05
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