The primary source of biodiesel obtainment in Brazil is concentrated in oleaginous vegetables, especially soy. However, there is a great hold-up caused by competition with the food industry, which makes the search for alternative pathways that do not compete with other industries needed. The goal of this study was to investigate the biotechnological potential of cyanobacteria, which were grown in two different culture media, as an alternative approach for obtaining biodiesel. For this purpose, Microcystis aeruginosa CACIAM03, CACIAM08, Synechocystis sp. CACIAM05, Lyngbya sp. CACIAM07, Cyanobium sp. CACIAM14, Leptolyngbya sp. CACIAM18, Limnothrix redekei CACIAM25 and Planktothrix pseudoagardhii CACIAM27 were evaluated. Fatty acid composition was determined using gas chromatography. Fatty acids found in all strains were identified as palmitic acid (C16:0) (7.43–38.37% content), stearic acid (C18:0) (1.44–13.82%), caproic acid (C6:0) (0.82–78.84%) and oleic acid (C18:1) (1.13–46.76%). The biodiesel quality parameters were calculated based on the fatty acid profile. Strains that showed the best values and provided better biodiesel quality were Synechocystis sp. CACIAM05 and Microcystis aeruginosa CACIAM03 that were grown in BG-11 medium. This study showed us a promising source of biodiesel production from cyanobacterial lipids based on empirical calculations of the parameters of biodiesel quality that met the fuel standards. Furthermore, our results suggest the production of fatty acids through a metabolic route, due to the change in the profile of fatty acids in both culture media, providing valuable information for future engineering to increase the percentage of fatty acids that give better biodiesel quality.

The objective of this study, for the first time, was to optimize Amazonian cyanobacterial culture conditions for improving cell productivity and lipid content, by analyzing the effect of light intensity and nitrogen concentration, for empirically evaluating biodiesel quality parameters. The strains Synechocystis sp. CACIAM05, Microcystis aeruginosa CACIAM08, Pantanalinema rosaneae CACIAM18, and Limnothrix sp. CACIAM25, were previously identified by morphological and molecular analysis (16S rRNA) and were selected based on their production of chlorophyll a and dry cell weight. Then, factorial planning (2²) with central points was applied, with light intensity and NaNO₃ concentration as independent variables. As response variables, cell productivity and lipid content were determined. Statistical analysis indicated that for all strains, the independent variables were statistically significant for cell productivity. Analysis of the fatty acid composition demonstrated diversity in the composition of the fatty acid profile from the experimental planning assays of each strain. The Biodiesel Analyzer software predicted the biodiesel quality parameters. CACIAM05 and CACIAM25 obtained better parameters with low levels of light intensity and NaNO₃ concentration, whereas CACIAM08 and CACIAM18 obtained better parameters with low NaNO₃ concentrations and high luminous intensity.

A new prepared catalyst, 12-molybdophosphoric acid (HPMo) anchored to the mesoporous aluminosilicate AlSiM, synthesized from Amazon kaolin, was characterized and used as a heterogeneous acid catalyst for the production of eugenyl acetate by acetylation of eugenol with acetic anhydride. The effect of various reaction parameters, such as catalyst concentration, eugenol/acetic anhydride molar ratio, temperature and reaction time, was studied to optimize the conditions of maximum conversion of eugenol. The kinetics studies showed that in eugenol acetylation, the substrate concentration follows a first order kinetics. The results of activation energy was 19.96 kJ mol⁻¹ for HPMo anchored to AlSiM. The reuse of the catalyst was also studied and there was no loss of catalytic activity after four cycles of use (from 99.9% in the first cycle to 90% in the fifth cycle was confirmed), and an excellent stability of the material was observed. Based on catalytic and kinetic studies, HPMo anchored to AlSiM is considered an excellent catalyst.

Due the worldwide need to improve care for the environment and people, there is a great demand for the development of new renewable, sustainable, and less polluting technologies for food, health, and environmental industries. The marine environment is one of the main areas investigated in the search for alternatives to the raw materials currently used. Thereby, cyanobacteria and marine microalgae are microorganisms that are capable of producing a diverse range of metabolites useful for their cellular maintenance, but that also represent a great biotechnological potential. Due its great potential, they have an enormous appeal in the scientific research where, the biological activity of metabolites produced by these microorganisms, such as the antioxidant action of sterols are, some examples of biotechnological applications investigated around the world. Thereby, Brazil due to its extensive biodiversity, has high potential as a raw material supplier of marine waters, researching cyanobacteria and microalgae metabolites and their applications. Thus, this rapid review intends to present some important contributions and advances from Brazilian researchers, using the biomass of Brazilian cyanobacteria and marine microalgae, in order to illustrate the value of what has already been discovered and the enormous potential of what remains unexplored so far.