Bioprocesses and biotechnological potential in Gracilaria species (Rhodophyta, Gracilariales): physiological and biochemical approach

Abstract

Benthic marine algae are sources of compounds of commercial and biotechnological interest, and can be biofilters, since they use the nutrients of the medium in their metabolism. Species of Gracilaria Greville are exploited as raw material for the agar production and studies on their development are necessary for the sustainable production of biomass, agar and new bioactive compounds. The present study aims to evaluate the effects of nutrient availability (nitrogen and phosphorus) in the metabolism and biotechnological potential of Gracilaria caudata J. Agardh and G. domingensis (Kützing) Sonder ex Dickie. Experiments will be performed with nitrate addition (zero, 50, 125, 250 and 500 ¼M) and phosphate in the ratio of 10: 1 to 100: 1. Each treatment will be tested with three replicates (n = 3). The following physiological and biochemical variables will be analyzed: growth rates, photosynthesis, morphometry, concentrations of total soluble proteins, carbohydrates and pigments (chlorophyll A, phycoerythrin, phycocyanin and allophycocyanin), and thallus contents of carbon, hydrogen, nitrogen and phosphorus. To evaluate the biotechnological potential, properties of the agar will be determined (yield, and quantification of sulfate and 3, 6-anhydrogalactose levels), and biological activity tests will be performed (antioxidant and inhibitory activity of the enzyme acetylcholinesterase) with extracts produced by bioreactors compared with field-collecting material. (AU)