Caracterização genômica e biotecnologica das microalgas Chlamydomonas biconvexa e Dunaliella viridis

Abstract

Microalgae have the potential to produce a variety of active ingredients of industrial interest, whether in the food industry, due to the high protein and carbohydrate content of their biomass; or in the treatment of agro-industrial effluents, such as POME (Palm oil mil effluent). It can also be used in the industry to produce assets with high added value, such as carotenoid pigments, which are used in cosmetics, animal nutrition, and human food. Among the species with biotechnological potential, two strains isolated from Brazilian environments stand out: the freshwater Chlamydomonas biconvexa Embrapa|LBA40 and the halotolerant species Dunaliella viridis Embrapa|LBAS001. This study showed that the strain C. biconvexa Embrapa|LBA40, isolated and cultivated in palm oil industry effluent (POME), was able to achieve biomass productivity of 190.60 mg DW • L-1 • d-1 in 15L flat plate airlift photobioreactors. The species was able to reduce ammonia and nitrite from the POME residue by 99%, as well as reducing phosphate by 98% after 5 days of cultivation. In addition, the mitochondrial genome was obtained through genetic sequencing, revealing an mtDNA of 15.98 Kb, with 14 genes, 9 of which are protein-coding genes. Phylogenetic analysis using the COX1 gene confirmed the taxonomic identification as C. biconvexa, opening opportunities for future genetic studies to modify and improve the species. The microalgae strain Dunaliella viridis EMBRAPA| LBA#S001, isolated from saline lagoons in Brazil, was studied for its morphological and genomic characteristics. The strain was identified by molecular markers, such as the rbcL and ITS2 genes, and demonstrated high tolerance to high salinities, with consistent growth in NaCl concentrations of up to 4.8 M. The production of β-carotene was evaluated, resulting in 18.7 mg/L, comparable to the levels found in other species of the genus. The mitochondrial DNA revealed a genome of 46.2 Kbp, while the chloroplast genome reached 197.1 Kb, both with genes essential for photosynthesis. The analysis of the nuclear genome, with 176.9 Mb, identified 29,594 protein-coding genes, indicating a significant potential for biotechnology. The study analyzed the resistance genes in the strain, identifying mechanisms such as antibiotic target switching and antibiotic efflux. The presence of genes such as vanY and adeF suggests adaptive diversity in contaminated environments. Analysis of transcription factors highlights the regulation of genes essential for photosynthesis and stress responses. Manipulating these factors could increase the production of valuable compounds such as carotenoids. The development of synthetic promoters is crucial to optimizing microalgae as biotechnological platforms, compared to more traditional organisms.