Produção de enzima alginase a partir de fungos filamentosos e algas marinhas marrons S (Sargassum)

Abstract

Thisstudy describesthe semi-solid fermentation for producing alginase from filamentousfungi using brown macro algae as substrate. The macroalgae chosen was Sargassum´genus, and of the fungal strains tested, the fungus Cunninghamella echinulata proved to be more suitablefor the optimization of fermentation. All fermentations took place in vitro using 3g of macroalgal biomass at a temperature of 30ºC, with enzymatic extract obtained in 50 mM tris-HCl pH 7.2- 7.5 through stirring (150 rpm for 30 min), followed by by filtration and centrifugation (3000 rpm for 15 min) to separate the solid part of the extract. The humidifying nutrient solution (SN) was composed of the following composition: urea (0.30 g / L), peptone (0.75 g / L), (NH4)2SO4 (1.40 g / L), KH2PO4 (2 g / L), MgSO4.7H2O (0.30 g / L), CaCl2.2H2O (0.40 g / L), ZnSO4.7H2O (1.40 mg / L), FeSO4.7H2O (5.0 mg / L) ), CoCl2.6H2O (2.0 mg / L) and MnSO4.4H2O (1.60 mg / L). We sought to optimize this nutrient solution in relation to nitrogen levels, and it was found that the increased concentration of peptone (5 g / L) and inclusion of yeast extract (2 g / L) (called SN2 being used in all subsequent fermentations) favored an increase in the development of the fungus with and increase in enzymatic expression from 100 to 225 U / mL. On the other hand, the increase in the concentration of nitrogen from this formulation resulted in a reduction in enzyme production. The study of the influence of humidity revealed that when using levels of 65-85, optimal production of the enzyme was obtained. With humiditybetween 80 and 85%, the enzyme production was near negligible. Production peaks reached a yield of up to 175 U / mL. The variation of the inoculum concentration between 2.106 - 1.107 spores / gbiomass, did not significantly alter the alginase production, presenting itself as a safe working interval. The presence of sodium alginate as an inducer in enzyme expression allowed na increase of 43% in enzyme production, jumping from a peak of enzymatic activity from 175 to 250 U / mL, using a mass substitution of Sargassum biomass between 16.66- 33.33% (malgianto / mtotal). The pH effect of SN2 was studied in the range 2.5-8.5, with maximum production When adjusted between 6.0 and 7.0. In addition, the enzymatic extract obtained by semi-solid fermentation showed stability to freezing, showing qualitatively the stability and resumption of enzyme activity and the components present in the extract.