Update on the application of magnetic fields to microalgal cultures.

Several studies have shown that any magnetic field (MF) applied to microalgae modifies its cultivation conditions and may favor biomolecule production since it interacts with the microorganisms and affect their growth. As a result, there are changes in concentrations and compositions of biomass and biomolecules. This review aims at updating MF applications to microalga cultures that were reported by studies conducted in the last 5 years. It shows the main studies that reached positive results of carbohydrate, lipid, protein and pigment production. Effects of MFs may be positive, negative or null, depending on some factors, such as intensity, exposure time, physiological state of cells and application devices. Therefore, this review details cultivation conditions used for reaching high concentration of biomolecules, explains the action of MFs on microalgae and describes their applicability to the biorefinery concept.

Analysis and Modeling of Innovations in the Global Microalgae Lipids Market.

Microalgae lipids offer numerous advantages over those of plants and animals, enabling the sustainable commercialization of high value-added products in different markets. Although these markets are in a vertiginous annual expansion, technological life cycle modeling is a tool that has been rarely used for microalgae. Life cycle modeling is capable of assisting with decision-making based on data and is considered as a versatile model, usable in multiple software analyzing and diagnostic tasks. Modeling technological trends makes it possible to categorize the development level of the market and predict phase changes, reducing uncertainties and increasing investments. This study aims to fill this gap by performing a global analysis and modeling of microalgal lipid innovations. The Espacenet and Orbit platforms were used by crossing the keywords "microalgae", "lipid*", and the IPC code C12 (biochemistry and microbiology). Different sigmoid growth models were used in the present study. A successive repetition of the Chlorella genus category was found in the keyword clusters regarding extraction and separation of lipids. The life cycle S curve indicates a market starting at the maturity phase, where the BiDoseResp model stands out. The main countries and institutions at the technological forefront are shown, as well as potential technological domains for opening new markets.

Effect of Magnetopriming on Photosynthetic Performance of Plants.

Magnetopriming has emerged as a promising seed-priming method, improving seed vigor, plant performance and productivity under both normal and stressed conditions. Various recent reports have demonstrated that improved photosynthesis can lead to higher biomass accumulation and overall crop yield. The major focus of the present review is magnetopriming-based, improved growth parameters, which ultimately favor increased photosynthetic performance. The plants originating from magnetoprimed seeds showed increased plant height, leaf area, fresh weight, thick midrib and minor veins. Similarly, chlorophyll and carotenoid contents, efficiency of PSII, quantum yield of electron transport, stomatal conductance, and activities of carbonic anhydrase (CA), Rubisco and PEP-carboxylase enzymes are enhanced with magnetopriming of the seeds. In addition, a higher fluorescence yield at the J-I-P phase in polyphasic chlorophyll a fluorescence (OJIP) transient curves was observed in plants originating from magnetoprimed seeds. Here, we have presented an overview of available studies supporting the magnetopriming-based improvement of various parameters determining the photosynthetic performance of crop plants, which consequently increases crop yield. Additionally, we suggest the need for more in-depth molecular analysis in the future to shed light upon hidden regulatory mechanisms involved in magnetopriming-based, improved photosynthetic performance.

Magnetic field as promoter of growth in outdoor and indoor assays of Chlorella fusca.

This study aimed to evaluate the influence of a magnetic field (MF) intensity of 25 mT on Chlorella fusca cultivation in outdoor and indoor conditions, and evaluate the changes in the macromolecules, pigment content and protein profile. C. fusca was cultivated for 15 d in raceway photobioreactor. MF was applied for 24 h d-1 and 1 h d-1. In outdoor cultivation, MF applied for 24 h d-1 increased 23% in the biomass concentration, while indoor assays resulted in an increase in both modes, with biomass production increasing between 70 and 85%. Biomass composition was altered when MF was applied for 1 h d-1 in indoor assays; the highest protein content was achieved (32.7%). Nitrate consumption was higher in outdoor assays, while MF application did not alter the protein profile. The results showed that combining the outdoor conditions with MF is advantageous, as higher biomass concentration can be achieved with lower energy expenditure.

Simultaneous saccharification and fermentation of Spirulina sp. and corn starch for the production of bioethanol and obtaining biopeptides with high antioxidant activity.

The aim was to produce bioethanol by the simultaneous saccharification and fermentation (SSF) of Spirulina sp. LEB 18 biomass and corn starch, increasing the process scale and obtaining biopeptides from bioethanol residue. Different temperatures of SSF and biomass/starch concentrations were tested, and the best conditions were chosen to scale-up the bioethanol production. The biopeptides were obtained enzymatically with a protease. The antioxidant capacity, molecular structure, thermal stability and mass loss of the biopeptides were evaluated. A total of 73 g L-1 bioethanol was obtained during scale-up, and the residue presented a high protein content with a degree of hydrolysis of 86%. The biopeptides showed 32% ABTS radical inhibition with high thermal stability. This study showed the possibility of the biorefinery concept being able to produce bioethanol by Spirulina, and the biopeptides from the bioethanol residue presented high antioxidant capacity and can be used in many areas of the food industry.

Quantum yield alterations due to the static magnetic fields action on Arthrospira platensis SAG 21.99: Evaluation of photosystem activity.

Static magnetic fields (SMF) influence the metabolism of microorganisms, however, there is no knowledge explaining how SMF act in cells. This study aimed at evaluating the SMF (30 mT) effect on photosynthetic performance, growth and biomass composition of the cyanobacterium Arthrospira platensis SAG 21.99. A. platensis was cultivated under 30 mT applied for 1 h d-1 and 24 h for 10 d in glass bottles. SMF in both conditions increased cellular growth, achieving a 30% higher biomass concentration. SMF applied for 1 h d-1 increased the pigments and carbohydrate content. The quantum yield was used as an indicator of the photosystem II (PSII) activity and was shown to have been positively affected. SMF for 1 h d-1 had a significant effect on the OJIP curves. This is the first study that evaluated the photosynthetic activity in cyanobacteria cultures under SMF action.

Biological CO2 mitigation by microalgae: technological trends, future prospects and challenges.

The increase in the CO2 concentration in the Earth's atmosphere has been a topic of worldwide concern since anthropogenic emissions of greenhouse gases began increasing considerably during the industrial period. The effects of these mass emissions are probably the main cause of global warming, which has been observed over recent decades. Among the various techniques of CO2 capture, microalgal biofixation by photosynthesis is considered a promising technology due to the efficiency of these microorganisms in converting this gas into organic compounds through its use as a nutrient in the culture medium. Over the years, several research centers have developed studies on this subject, which have focused on mainly the development of bioreactors, the growth conditions that increase the efficiency of the process and the production of biomass with applicability in several areas. The biological mitigation of CO2 by microalgae has many advantages, including reductions in the concentration of an industrially sourced greenhouse gas and the energy or food obtained from the produced photosynthetic biomass. This versatility allows for the cultivation of economically useful biomass while reducing the environmental impacts of industrial facilities. In this context, this mini-review aims to discuss new technologies and strategies along with the main challenges and future prospects in the field and the ecological and economic impacts of CO2 biofixation by microalgae.

Use of static magnetic fields to increase CO2 biofixation by the microalga Chlorella fusca.

This study aimed to use different conditions of magnetic field (MF) application during Chlorella fusca cultivation and evaluate CO2 biofixation by the microalga through growth kinetics in addition to the biomass composition. For this purpose, we tested different MF intensities applied for 1 h d-1 and for 24 h. Cultures exposed to the MF for 1 h d-1 (in both intensities) had greater biomass concentrations (1.42 g L-1) and 34% more productivity in the same time as the control assay. The biofixation rate increased by 50% with 60 mT for 1 h d-1, and the protein content was enhanced by 30 mT (56.21% w w-1). This study was the first to consider the MF effect on CO2 biofixation. MF applied for 1 h d-1 proved to be an efficient alternative method to increase the CO2 biofixation and growth of C. fusca besides to be an inexpensive and nontoxic method.

Magnetic field action on outdoor and indoor cultures of Spirulina: Evaluation of growth, medium consumption and protein profile.

This study aimed at evaluating whether a magnetic field (MF) affects the growth of Spirulina sp. when applied to it at different exposure times in indoor and outdoor culture systems. The effects of MF on chlorophyll content, medium consumption and protein profile were also investigated. In raceway tanks, a 25 mT MF was applied for 24 h or for 1 h d-1. MF for 24 h to outdoor assays increased biomass concentration and chlorophyll-a content besides altering the protein profile. Outdoor Spirulina growth was higher (∼3.65 g L-1) than the growth found in indoor assays (∼1.80 g L-1), while nitrogen and phosphorus consumption was not enhanced by the application of MF. This is the first study that investigated the influence of MF on outdoor microalga assays, and the results showed that MF affected the metabolism of Spirulina cultured in raceways, especially when it was grown outdoors in uncontrolled environmental conditions.

Magnetic treatment of microalgae for enhanced product formation.

Static or modulated magnetic fields (MF) may interact with the biological system and affect the metabolism of microorganisms, such as their photosynthetic capacity or synthesis of carbohydrates. Their effects on microorganisms, which can be classified into inhibiting, stimulating and null, may be interpreted as the result of stress that cells undergo, thus, leading to responses through the same mechanisms. Biological effects of exposure to magnetic forces depend on magnetic intensity, frequency and exposure time. Modifications in these parameters may enhance product formation. Effects differ according to the form and application of MF characteristic parameters. Magnetic treatments have the advantages of being convenient and non-toxic, having low running cost, emitting no secondary pollution, enabling wide application and being easily shielded. MF application to the cultivation of microalgae, to improve the production of finished biomolecules, is a simple, inexpensive and powerful process. However, bioeffects of MF on microalgae need to be further investigated because there have currently been very few available reports in the literature. Thus, studies which aim at optimizing parameters involved in MF application must be developed in order to obtain the best conditions for the production of molecules with high economic potential.

Simultaneous Production of Amyloglucosidase and Exo-Polygalacturonase by Aspergillus niger in a Rotating Drum Reactor.

Simultaneous production of amyloglucosidase (AMG) and exo-polygalacturonase (exo-PG) was carried out by Aspergillus niger in substrate of defatted rice bran in a rotating drum bioreactor (RDB) and studied by a 31 × 22 factorial experimental design. Variables under study were A. niger strains (A. niger NRRL 3122 and A. niger t0005/007-2), types of inoculum (spore suspension and fermented bran), and types of inducer (starch, pectin, and a mix of both). Solid-state fermentation process (SSF) was conducted at 30 °C under 60-vvm aeration for 96 h in a pilot scale. Production of AMG and exo-PG was significantly affected by the fungal strain and the type of inoculum, but inducers did not trigger any significant effect, an evidence of the fact that these enzymes are constitutive. The maximum activity of exo-PG was 84 U gdm-1 whereas the maximum yield of AMG was 886.25 U gdm-1.

Magnetic fields as triggers of microalga growth: evaluation of its effect on Spirulina sp.

This study aimed at evaluating the influence of magnetic field on the growth and biomass composition of Spirulina sp., cultivated in vertical tubular photobioreactors. Magnetic fields of 5, 30 and 60mT generated by electric current and ferrite magnets were applied at different lengths of time. The magnetic field of 30 and 60mT for 1hd(-1) stimulated the growth, thus leading to higher biomass concentration by comparison with the control culture. Increase in productivity, protein and carbohydrate contents were 105.1% (60mT for 1hd(-1)), 16.6% (60mT for 24hd(-1)) and 133.2% (30mT for 24hd(-1)), respectively. These values were higher than the ones of the control. Results showed that magnetic field may influence the growth of Spirulina sp., since it triggers a stimulating effect and can leads to twofold biomass concentration in equal cultivation time periods.