Exploratory data of the microalgae compounds for food purposes

This brief data article refers to the previous exploration of Scenedesmus obliquus and Phormidium autumnale biomass about the possibility of using these microalgae species as an unconventional functional food. Data on chemical composition, fatty acids, volatile compounds, and carotenoid profiles were determined. In parallel, are provided the antioxidant capacity (reducing capacity - RC and reactive oxygen species deactivation - ORAC) of aqueous, lipophilic, and carotenoid extracts isolated from microalgae biomass. Both species have similar compounds in their biomass. However, S. obliquus was statistically different with a lower saturated fatty acid (STF) followed by higher mono (MUFA) and polyunsaturated (PUFA) content, also showed higher antioxidant potential for acetone extract and isolated carotenoids. On the other hand, P. autumnale aqueous extract showed high RC and ORAC. The significance of the experimental data was determined using the t-test (p < 0.05) based on the Statistica 7.0 software. These findings led us to explore the microalgae S. obliquus in an in vivo experimental model.

Insights in cyanobacteria lipidomics: A sterols characterization from Phormidium autumnale biomass in heterotrophic cultivation

Sterol profiles were obtained from cyanobacteria Phormidium autumnale, cultivated in a heterotrophic system using three distinct sources of carbon: glucose, sucrose, and agroindustrial slaughterhouse wastewater. A simultaneous saponification-extraction ultrasound-assisted method was performed to determine sterol and other non-saponified compounds in the dry biomasses. A total of 24 compounds were observed in the biomasses, including hope-22,29-en-3-one, squalene, and 22 other sterols. Using wastewater as a carbon source, the microalgae biomass produced a diversity of sterols such as stigmasterol (455.3 μg g^-1) and β-sitosterol (279.0 μg g^-1). However, with glucose it is possible to produce ergosterol (1033.3 μg g^-1). Squalene was found in all the cultures, with 1440.4 μg g^-1, 225.4 μg g^-1, and 425.6 μg g^-1 for glucose, sucrose, and slaughterhouse wastewater biomasses, respectively. Several intermediate compounds from those sterols were found. These data provide the construction of the sterol metabolism according to the literature for P. autumnale heterotrophically cultured.

Life Cycle Assessment (LCA) of Third-Generation Biodiesel Produced Heterotrophically by Phormidium Autumnale

Objectives:

The aim of this work was to perform a prospective life cycle assessment of the third-generation biodiesel (3G) produced from the heterotrophic cultivation of Phormidium autumnale, using sucrose as the carbon source.

Materials and Methods:

The study focused on the optimization of the process parameters, in the life cycle assessment and in the biofuel quality analysis in diverse microalgae-based scenarios.

Results:

In the best scenario, the production of microalgal biodiesel has positive energy production (50.59 MJ/kg) associated with low consumption of water (28.38 m3/kg) and low CO2 emissions (9.18 kg CO2-eq/kg). In terms of composition, this oil was predominantly saturated (45.20%), monounsaturated (34.70%), and polyunsaturated (19.90%), resulting in a biodiesel that complies with U.S., European, and Brazilian standards.

Conclusion:

The high potential capacity for lipid production obtained is interesting for the generation of quality biodiesel that meets or surpasses the most stringent U.S., European, and Brazilian fuel standard requirements.

Carotenoid profile of three microalgae/cyanobacteria species with peroxyl radical scavenger capacity

Carotenoids from cyanobacteria Aphanothece microscopica Nageli and green microalgae Chlorella vulgaris and Scenedesmus obliquus were identified. The total carotenoid content, based on dry weight of biomass, of A. microscopica Nägeli, C. vulgaris and S. obliquus were 1398.88μg/g, 1977.02μg/g and 2650.70μg/g, respectively. A total of 23 different carotenoids were separated in all the extracts, the major ones being all-trans-β-carotene (29.3%) and all-trans-lutein (28.1%) in Scenedesmus; all-trans-echinenone (22.8%) and all-trans-β-carotene (17.7%) in Chlorella; all-trans-echinenone (28.3%) and all-trans-β-carotene (26.2%) in Aphanothece. The carotenoid extracts were shown to be a potent scavenger of peroxyl radical, with values of 31.1 (Chlorella), 14.0 (Scenedesmus) and 7.3 (Aphanothece) times more potent than α-tocopherol.

Heterotrophic Cultivation of Cyanobacteria: Study of Effect of Exogenous Sources of Organic Carbon, Absolute Amount of Nutrients, and Stirring Speed on Biomass and Lipid Productivity

The production of bioproducts from cyanobacteria with techno-economic feasibility is a challenge to these biotechnological processes. The choice of low-cost raw materials is of great importance for the overall economy of bioprocesses, as they represent a significant percentage in the final cost of the product. The objective of this work was to study the operational parameters of cultivation (exogenous sources of organic carbon and absolute amount of nutrients) to optimize productivity in bioproducts by Aphanothece microscopica Nägeli, for further evaluation of stirring speed. The experiments were performed in a bubble column bioreactor, operating at 30°C, pH of 7.6, C/N ratio of 20, 100 mg/L of inoculum, continuous aeration of 1 volume of air per volume of culture per minute (VVM), and absence of light. The results indicate that absolute amounts of 5,000/250 using cassava starch resulted in improved system performance, reaching biomass productivity of 36.66 mg/L/h in parallel with lipid productivity of 6.65 mg/L/h. Finally, experiments with variation in stirring speed indicate that 200 rpm resulted in better average rate of substrate consumption (44.01 mg/L/h), in parallel to biomass productivity of 39.27 mg/L/h. However, the increase of stirring speed had a negative effect on lipid productivity of the process. The technological route developed indicates potential to production of biomass and bulk oil, as a result of the capacity of cyanobacteria to adapt their metabolism in varying culture conditions, which provides opportunities to modify, control, and thereby maximize the formation of targeted compounds.

The role of photoperiods on photobioreactors - A potential strategy to reduce costs

The aim of this work was evaluate the role of photoperiods (long-term, frequencies and short) on the growth and lipid content of microalgae Scenedesmus obliquus CPCC05. The results showed that Scenedesmus obliquus can store sufficient energy to sustain cell growth for continuous periods of up to 2h in the dark, without affecting the photosynthetic rate. The values for maximum biomass (9.58mg/Lh) and lipid productivities (2.56mg/Lh) were obtained at photoperiod of 0.91:0.09s (light:dark) and 48 t/d, respectively. Moreover, the best trade-offs between biomass productivity and light energy economy occurred in photoperiods of 0.5:0.5s and 0.91:0.09s (light:dark), and those between lipid productivity and light energy economy occurred in the frequency photoperiod of 24 and 48 t/d. Thus, the use of the photoperiods are an effective strategy for reducing costs of microalgal biomass production.