Michele Greque de Morais

Carbon dioxide fixation by Chlorella kessleri, C. vulgaris, Scenedesmus obliquus and Spirulina sp. cultivated in flasks and vertical tubular photobioreactors.

CO2 at different concentrations were added to cultures of the eukaryotic microalgae, Chlorella kessleri, C. vulgaris and Scenedesmus obliquus, and the prokaryotic cyanobacterium, Spirulina sp., growing in flasks and in a photobioreactor. In each case, the best kinetics and carbon fixation rate were with a vertical tubular photobioreactor. Overall, Spirulina sp. had the highest rates. Spirulina sp., Sc. obliquus and C. vulgaris could grow with up to 18% CO2.

The role of biochemical engineering in the production of biofuels from microalgae.

Environmental changes that have occurred due to the use of fossil fuels have driven the search for alternative sources that have a lower environmental impact. First-generation biofuels were derived from crops such as sugar cane, corn and soybean, which contribute to water scarcity and deforestation. Second-generation biofuels originated from lignocellulose agriculture and forest residues, however these needed large areas of land that could be used for food production. Based on technology projections, the third generation of biofuels will be derived from microalgae. Microalgae are considered to be an alternative energy source without the drawbacks of the first- and second-generation biofuels. Depending upon the growing conditions, microalgae can produce biocompounds that are easily converted into biofuels. The biofuels from microalgae are an alternative that can keep the development of human activity in harmony with the environment. This study aimed to present the main biofuels that can be derived from microalgae.

Biologically Active Metabolites Synthesized by Microalgae

Microalgae are microorganisms that have different morphological, physiological, and genetic traits that confer the ability to produce different biologically active metabolites. Microalgal biotechnology has become a subject of study for various fields, due to the varied bioproducts that can be obtained from these microorganisms. When microalgal cultivation processes are better understood, microalgae can become an environmentally friendly and economically viable source of compounds of interest, because production can be optimized in a controlled culture. The bioactive compounds derived from microalgae have anti-inflammatory, antimicrobial, and antioxidant activities, among others. Furthermore, these microorganisms have the ability to promote health and reduce the risk of the development of degenerative diseases. In this context, the aim of this review is to discuss bioactive metabolites produced by microalgae for possible applications in the life sciences.

Preparation of nanofibers containing the microalga Spirulina (Arthrospira)

Spirulina is a microalga which offers biological functions highly favorable for tissue engineering. Highly porous scaffolds can be produced by electrospinning containing biomass of Spirulina. The goal of this contribution was therefore to establish spinning conditions allowing to produce well defined nanofibers with diameters down to about 100 nm and to produce nanofibers with various concentration of the biomass for subsequent studies in tissue engineering applications. The experimental results reveal that the blend system PEO/biomass is behaved surprisingly well in electrospinning. Very thin bead-free nanofibers with diameters of about 110 nm can be produced for different biomass contents of up to 67 wt.% of the nanofibers and for PEO concentrations in the spinning solution well below 4 wt.%. These results suggest to us the use of the biomass containing nanofibers as extracellular matrices for stem cell culture and future treatment of spinal chord injury.

Development of a new nanofiber scaffold for use with stem cells in a third degree burn animal model.

The combination of mesenchymal stem cells (MSCs) and nanotechnology to promote tissue engineering presents a strategy for the creation of new substitutes for tissues. Aiming at the utilization of the scaffolds of poly-d,l-lactic acid (PDLLA) associated or not with Spirulina biomass (PDLLA/Sp) in skin wounds, MSCs were seeded onto nanofibers produced by electrospinning. These matrices were evaluated for morphology and fiber diameter by scanning electron microscopy and their interaction with the MSCs by confocal microscopy analysis. The biomaterials were implanted in mice with burn imitating skin defects for up to 7 days and five groups were studied for healing characteristics. The scaffolds demonstrated fibrous and porous structures and, when implanted in the animals, they tolerated mechanical stress for up to two weeks. Seven days after the induction of lesions, a similar presence of ulceration, inflammation and fibrosis among all the treatments was observed. No group showed signs of re-epithelization, keratinization or presence of hair follicles on the lesion site. In conclusion, although there was no microscopical difference among all the groups, it is possible that more prolonged analysis would show different results. Moreover, the macroscopic analysis of the groups with the scaffolds showed better cicatrization in comparison with the control group.

Simultaneous cultivation of Spirulina platensis and the toxigenic cyanobacteria Microcystis aeruginosa.

Abstract Mangueira Lagoon, located in the extreme south of Brazil, has water with physicochemical characteristics such as alkaline pH and carbonate levels propitious for the growth of the cyanobacterium Spirulina platensis. Previously published studies have shown that Mangueira Lagoon water supplemented with small quantities of carbon and nitrogen is suitable for S. platensis cultivation and can significantly reduce production costs. We studied mixed cultures of Spirulina platensis and the toxic cyanobacterium Microcystis aeruginosa using a 23 factorial design in which the three factors were the initial biomass concentration of S. platensis and M. aeruginosa and the type of culture medium (100% Zarrouk’s medium or 80% Mangueira Lagoon water plus 20% Zarrouk’s medium). The highest S. platensis maximum specific growth rate (μmax) occurred in the culture with the highest M. aeruginosa biomass concentration and when undiluted culture medium was used (μmax = 0.283 d-1). The highest M. aeruginosa specific death rate (k) was obtained in the presence of S. platensis (k = 0.555 d-1) and was independent of the initial M. aeruginosa biomass concentration and culture medium, demonstrating that S. platensis cultures are not susceptible to contamination by M. aeruginosa. The culture medium had no significant influence (p > 0.05) on S. platensis μmax values, indicating that production costs could be reduced by using a medium consisting of 80% Mangueira Lagoon water plus 20% Zarrouk’s medium

Biological effects of Spirulina (Arthrospira) biopolymers and biomass in the development of nanostructured scaffolds.

Spirulina is produced from pure cultures of the photosynthetic prokaryotic cyanobacteria Arthrospira. For many years research centers throughout the world have studied its application in various scientific fields, especially in foods and medicine. The biomass produced from Spirulina cultivation contains a variety of biocompounds, including biopeptides, biopolymers, carbohydrates, essential fatty acids, minerals, oligoelements, and sterols. Some of these compounds are bioactive and have anti-inflammatory, antibacterial, antioxidant, and antifungal properties. These compounds can be used in tissue engineering, the interdisciplinary field that combines techniques from cell science, engineering, and materials science and which has grown in importance over the past few decades. Spirulina biomass can be used to produce polyhydroxyalkanoates (PHAs), biopolymers that can substitute synthetic polymers in the construction of engineered extracellular matrices (scaffolds) for use in tissue cultures or bioactive molecule construction. This review describes the development of nanostructured scaffolds based on biopolymers extracted from microalgae and biomass from Spirulina production. These scaffolds have the potential to encourage cell growth while reducing the risk of organ or tissue rejection.

Bioprocess Engineering Aspects of Biopolymer Production by the Cyanobacterium Spirulina Strain LEB 18

Microbial biopolymers can replace environmentally damaging plastics derived from petrochemicals. We investigated biopolymer synthesis by the cyanobacterium Spirulina strain LEB 18. Autotrophic culture used unmodified Zarrouk medium or modified Zarrouk medium in which the NaNO3 content was reduced to 0.25 g L−1 and the NaHCO3 content reduced to 8.4 g L−1 or increased to 25.2 g L−1. Heterotrophic culture used modified Zarrouk medium containing 0.25 g L−1 NaNO3 with the NaHCO3 replaced by 0.2 g L−1, 0.4 g L−1, or 0.6 g L−1 of glucose (C6H12O6) or sodium acetate (CH3COONa). Mixotrophic culture used modified Zarrouk medium containing 0.25 g L−1 NaNO3 plus 16.8 g L−1 NaHCO3 with the addition of 0.2 g L−1, 0.4 g L−1, or 0.6 g L−1 of glucose or sodium acetate. The highest biopolymer yield was 44% when LEB 18 was growing autotrophically in media containing 0.25 g L−1 NaNO3 and 8.4 g L−1 NaHCO3.

Bioprocessos para remoção de dióxido de carbono e óxido de nitrogênio por microalgas

The aim of this work was to study the removal of CO2 and NO by microalgae and to evaluate the kinetic characteristics of the cultures. Spirulina sp. showed µmax and Xmax (0.11 d-1, 1.11 g L-1 d-1) when treated with CO2 and NaNO3. The maximum CO2 removal was 22.97% for S. obliquus treated with KNO3 and atmospheric CO2. The S. obliquus showed maximum NO removal (21.30%) when treated with NO and CO2. Coupling the cultivation of these microalgae with the removal of CO2 and NO has the potential not only to reduce the costs of culture media but also to offset carbon and nitrogen emissions.

CO2 Biofixation by the Cyanobacterium Spirulina sp. LEB 18 and the Green Alga Chlorella fusca LEB 111 Grown Using Gas Effluents and Solid Residues of Thermoelectric Origin

The concentration of carbon dioxide (CO2) in the atmosphere has increased from 280 to 400 ppm in the last 10 years, and the coal-fired power plants are responsible for approximately 22 % of these emissions. The burning of fossil fuel also produces a great amount of solid waste that causes serious industrial and environmental problems. The biological processes become interesting alternative in combating pollution and developing new products. The objective of this study was to evaluate the CO2 biofixation potential of microalgae that were grown using gaseous effluents and solid residues of thermoelectric origin. The microalgae Chlorella fusca LEB 111 presented higher rate of CO2 biofixation (42.8 %) (p < 0.01) than did Spirulina sp. LEB 18. The values for the CO2 biofixation rates and the kinetic parameters of Spirulina and Chlorella cells grown using combustion gas did not differ significantly from those of cells grown using CO2 and a carbon source in the culture media. These microalgae could be grown using ash derived from coal combustion, using the minerals present in this residue as the source of the essential metals required for their growth and the CO2 derived from the combustion gas as their carbon source.