Bioprospecting, characterization and optimization of Brazilian microalgal strains for CO2 biofixation and bioproducts of commercial importance

Abstract

This proposal focuses on microalgae physiology and biotechnology, starting from test tubes towards scaling up, in search for robust microalgae and their products that may be of commercial interest. Our goal is to identify strains that present high biomass yields and produce intracellular biomolecules with antioxidant, antibacterial, lipid, carbohydrate, amino acid, fatty acid, phytosterols and/or terpenoid properties, and/or extracellular polysaccharides with tensoactive properties. Our project has two main objectives, the prospecting of biomolecules with CO2 biofixation, and the production of biochemically characterized biomass. We include here the identification of strains from the Freshwater Microalgae Culture Collection (UFSCar), and the study of cryopreservation in light of physiological characterization as a guarantee for further germination. We will prospect about 300 strains, establish a library of extracts, and select strains for scaling up (100 - 1000 L). Due to the interdisciplinary nature of our proposed project, we integrate a multidisciplinary and interinstitutional team into cohesive working groups. In the laboratory, strains that produce exopolysaccharides/mucilage capsules will be tested for tensing properties. The biofixation of CO2 permeates all stages of this proposal as it is the basis for photosynthetic metabolism. In this regard, we intend to conclude with a model that facilitates the quantitation of the fixed gas, currently an unresolved issue. In relation to biomolecules, we will prospect for antioxidant, antibacterial, total lipids, proteins and carbohydrates, amino acids and fatty acids profiles, phytosterols, terpenes and energy potential. We will start the project with the goal of screening 60 strains/year. From the total of 300 strains, we will down-select to the 10 most promising strains based on CO2 biofixation, robustness in culture and biomolecules of interest. For these down-selected strains, we will apply biochemical manipulation through abiotic stress to increase the synthesis and accumulation of intracellular biomolecules. With the triad biofixation of CO2, robustness in cultivation, and biomolecules we will scale up to 100 - 500 L (greenhouse), and from these we will go to 1000 L cultures (planar and thin layer photobioreactors) with strains of best performance, which will be investigated through transcriptomics to learn the about metabolic routes of biomolecule and biomass production. The results obtained will be an important contribution to sectors of the society interested in the production of microalgae and/or biofixation of CO2, and to those that need to make such interest feasible, adding value to the biomass. In addition, we will contribute to basic information to phycology and keep a library of extracts with biologically and chemically characterized strains of microalgae available to the community. (AU)