Showing papers by "Michele Greque de Morais published in 2021"

Microalgae Polysaccharides: An Overview of Production, Characterization, and Potential Applications

Abstract: Microalgae and cyanobacteria are photosynthetic microorganisms capable of synthesizing several biocompounds, including polysaccharides with antioxidant, antibacterial, and antiviral properties. At the same time that the accumulation of biomolecules occurs, microalgae can use wastewater and gaseous effluents for their growth, mitigating these pollutants. The increase in the production of polysaccharides by microalgae can be achieved mainly through nutritional limitations, stressful conditions, and/or adverse conditions. These compounds are of commercial interest due to their biological and rheological properties, which allow their application in various sectors, such as pharmaceuticals and foods. Thus, to increase the productivity and competitiveness of microalgal polysaccharides with commercial hydrocolloids, the cultivation parameters and extraction/purification processes have been optimized. In this context, this review addresses an overview of the production, characterization, and potential applications of polysaccharides obtained by microalgae and cyanobacteria. Moreover, the main opportunities and challenges in relation to obtaining these compounds are highlighted.

Development of time-pH indicator nanofibers from natural pigments: An emerging processing technology to monitor the quality of foods

Abstract: Colorimetric indicators produced from nanofibers have a high contact surface area, allowing better interaction of the indicator with the external environment In this context, this study aimed to develop time-pH indicator nanofibers with natural pigments for use as an emerging technology in the control of food quality The polymeric solutions were prepared with 13% (w v−1) polycaprolactone (PCL) and 6% (w v−1) poly (ethylene oxide) (PEO) The natural dyes added to the polymeric solution were curcumin and quercetin (2%, w v−1) with the addition of 05 or 1% (w v−1) of phycocyanin Solutions with curcumin, quercetin, and phycocyanin only (2% w v−1) were also studied The color change monitoring was performed for 24 h, followed up every 1 h, using buffer solutions (pH 2 to 7) The condition with 2% (w v−1) phycocyanin showed a color variation (ΔE ≥ 5) noticeable to the human eye in the pH range 3–6 in 5 h of analysis Thus, the indicator developed with PCL/PEO nanofibers containing 2% (w v−1) of phycocyanin is a promising alternative in monitoring the quality of perishable foods, as it can visually estimate changes in pH over time

Static Magnetic Fields Effects on Polysaccharides Production by Different Microalgae Strains

Abstract: Microalgae are able to produce many valuable biomolecules, such as polysaccharides, that presents a large diversity of biochemical structures and functions as antioxidant, antifungal, anticancer, among others. Static magnetic fields (SMF) influence the metabolism of microorganisms and has been shown as an alternative to increase microalgae biomass, yield and compounds production. Especially, some studies have highlighted that SMF application could enhance carbohydrate content. This study aimed to evaluate different conditions of SMF on Spirulina and Chlorella in indoor and outdoor conditions, in order to confirm the influence of SMF on polysaccharides production, evaluating which polysaccharidic fraction could be enhanced by SMF and highlighting a possible modification in EPS composition. Starch from Chlorella and exopolysaccharides (EPS) from Spirulina were quantified and characterized. SMF increased the starch content in Chorella fusca biomass. EPS productions from A. platensis and Spirulina sp. were not significantly increased, and global composition appeared similar to the controls (constituted basically of 80–86% neutral sugars and 13–19% uronic acids). However, the monosaccharide composition analysis revealed a significant modification of composition, i.e., the amount of fucose, arabinose, rhamnose, galactose and glucuronic acid was increased, while the glucose content was decreased. SMF application led to significant modification of polysaccharides production and this study demonstrate that combining the outdoor conditions with SMF, the starch content and EPS composition was positively affected.

Role of microalgae in circular bioeconomy: from waste treatment to biofuel production

Abstract: The rapid increase in human population and industrialization have caused severe environmental impacts, such as the depletion of energy and water resources, increase in carbon emissions, and contamination of water bodies. Thus, innovative ways to reduce these issues are essential and also a challenge. In this regard, the circular bioeconomy model has attracted attention, since it aims the sustainable production, utilization of renewable resources, and conversion into value-added products. Microalgal biotechnology represents a promising approach to this concept. These microorganisms can convert nutrients from solid, liquid, and gaseous wastes into biomass with potential as a feedstock for obtaining bioproducts. The simultaneous or sequential extraction of these products in a microalgae-based biorefinery could be an alternative to improve the economic feasibility of the process. Hence, this review article highlights the application of microalgae to carry out waste treatment and produce biofuels and biofertilizers within the circular bioeconomy concept. The challenges and opportunities are also briefly addressed.

Development of pH indicators from nanofibers containing microalgal pigment for monitoring of food quality

Abstract: The objective of the study was to develop pH indicator membranes from polymeric nanofibers with phycocyanin and to evaluate the irreversibility of the system. The polymeric solutions were prepared with 13% (w/v) polycaprolactone (PCL) and 6% (w/v) poly (ethylene oxide) (PEO), with varying phycocyanin concentrations of 0.5, 1 and 2% (w/v) phycocyanin with chloroform and distilled water (8:2) as the solvent. The electrospinning technique was used to form polymeric nanofibers. PCL/PEO nanofibers developed with 2% (w/v) of phycocyanin presented a smaller average diameter (875 nm) when compared to the membranes produced with 0.5 and 1% (w/v) of the pigment. Through the thermal analysis, events associated with the elimination of volatiles, free water, and bound water were observed. The phycocyanin encapsulation efficiency in PCL/PEO nanofibers with 0.5, 1, and 2% (w/v) phycocyanin was 97.7, 97.8, and 91.7%, respectively. The nanofibers with the addition of 1 and 2% (w/v) of microalgal pigment showed slightly hydrophobic characteristics (contact angle>90.0°). The nanofibers of 13% PCL and 6% PEO with 2% (w/v) phycocyanin when tested in pH buffers ranging from 3 to 4 and 5–6 showed color variation values ≥ 8.5. Thus, PCL/PEO nanofibers containing 2% (w/v) phycocyanin become a promising alternative as indicators in packaging to monitor the viability of food.

Outdoor Production of Biomass and Biomolecules by Spirulina (Arthrospira) and Synechococcus cultivated with Reduced Nutrient Supply

Abstract: Microalgal production conducted outdoors using low-cost cultivation media is important for the consolidation of this bioprocess on a large scale. In this context, the use of a chemically defined medium with reduced costs can not only provide nutritional security but also contribute to an increase in the concentration of biomolecules without a loss of microalgal biomass productivity. Thus, this study aimed to evaluate the biomass production and biomolecule concentrations of Spirulina sp. LEB 18 and Synechococcus nidulans LEB 115 in outdoor cultivation using media containing reduced nutrients. Algal performance was assessed in open raceway bioreactors, using three different culture media, namely, BG-11, standard Zarrouk, and a modified Zarrouk [reduction in the sources of carbon (83%), phosphorus (94%), nitrogen (40%), and magnesium (63%) concerning the standard Zarrouk medium]. Cultivation of Spirulina sp. LEB 18 in the modified Zarrouk medium promoted the shortest generation time (2.10 days), with the concentration of carbohydrate produced (37.1%) being 346% higher than that produced using the standard Zarrouk medium (8.3%). Similarly, compared with the Zarrouk medium, the modified Zarrouk medium promoted higher biomass productivity of S. nidulans LEB 115 (0.19 g L−1 d−1) along with a 160% increase in the concentration of carbohydrates (21.6%) produced by this strain. Thus, for the examined microalgal strains, the use of the modified Zarrouk medium enhanced the potential carbohydrate production and maintained the protein concentration above 39%, thereby indicating that this medium would be a promising candidate for the cost-effective large-scale production of microalgal biomass.

Microalgae as source of edible lipids

Abstract: Polyunsaturated fatty acids (PUFAs) are essential compounds for human health, being responsible for a series of biological processes including reduction of inflammation and prevention of neurological and cardiovascular diseases. Because they are not naturally produced by vertebrates, they need to be present in the diet. Microalgae are rich in PUFAs being able to accumulate from 20% to 50% of their dry weight in lipids. Moreover, some species have demonstrated high potential for food purposes, accumulating eicosapentaenoic and docosahexaenoic, two n-3 PUFAs that are in great demand. The lipid concentration and fatty acid profile of microalgae can be modulated as a lipid increase can be induced by stress conditions applied to cultivations, including the limitation of nutrients (mainly nitrogen and phosphorus), and increased temperature, salinity, and/or light intensity. Additional strategies can be used for the development of improved microalgal strains; natural populations can be enriched in subpopulations of spontaneously mutated cells or in which random mutations have been induced to produce strains with improved lipid or, more specifically, PUFA contents. Despite these advantages, the use of microalgae as sources of edible lipids still presents some constraints as mass production of microalgae for food purposes is expensive, requiring the use of closed photobioreactors to avoid contamination. Furthermore, lipid induction strategies often impair growth, forcing the use of two-stage growth approaches that can be difficult to implement at an industrial scale. Due to the difficulties in the scaling-up process, more efficient methods for microalgal harvesting and lipid extraction are needed. Despite all these issues, some products can already be found in the market, mainly as nutritional supplements in the forms of capsules and tablets of whole biomass, or as cooking oils and food flavorants.