Physical and biological fixation of CO2 with polymeric nanofibers in outdoor cultivations of Chlorella fusca LEB 111.

The objective of this study was to cultivate Chlorella fusca LEB 111 with nanofibers indoors and outdoors to verify the effect on CO2 biofixation and macromolecule production. The microalgae were cultured with 10% (w v-1) polyacrylonitrile (PAN)/dimethylformamide (DMF) nanofibers containing 4% (w v-1) iron oxide nanoparticles (NPsFe2O3), which were added to the cultivations at concentrations of 0, 0.1, 0.3 and 0.5 g L-1. The CO2 biofixation was higher in outdoor assays (270.6 and 310.9 mg L-1 d-1) than in indoor assays (124.6 and 131 mg L-1 d-1) with 0.1 and 0.3 g L-1 nanofibers, respectively. The outdoor assays with 0.3 g L-1 nanofibers had 10.9% greater lipid production than the assays without nanofibers. Thus, this first study of outdoor cultivations with nanofibers as physical adsorbents of CO2 showed the effect of nanostructures in maximizing gas biofixation and producing biomolecules that can be used to obtain bioproducts.

Development of Bioactive Nanopeptide of Microalgal Origin.

The objective of this work was to produce nanoparticles containing bioactive peptides obtained by the enzymatic hydrolysis reaction of microalgal biomass. The hydrolysates were purified by vacuum filtration with membranes of different sizes and by vertical column membranes. After each step, an antioxidant activity test was conducted. The nanoparticles were developed by nanoatomization, with the size and morphology of the particles analyzed by scanning electron microscopy (SEM). The microalgae hydrolysates showed high antioxidant activity compared to non-hydrolyzed biomass. The nanoatomization of bioactive peptides caused no significant reduction in antioxidant activity, with maximum reductions of 15.0 and 17.4% by DPPH assay and 2.5 and 3.8% determined by reducing power assay for Spirulina LEB 18 and Chlorella pyrenoidosa, respectively, with no reduction in the ABTS values. Nanoparticles with sizes ranging from 14­18 nm and 72­108 were obtained for the Spirulina and Chlorella hydrolysates, respectively.

Nanoencapsulation of the Bioactive Compounds of Spirulina with a Microalgal Biopolymer Coating.

Microalgae have been studied in biotechnological processes due to the various biocompounds that can be obtained from their biomasses, including pigments, proteins, antioxidants, biopeptides, fatty acids and biopolymers. Microalgae biopolymers are biodegradable materials that present similar characteristics to traditional polymers, with the advantage of being rapidly degraded when discarded. In addition, nanoencapsulation is capable of increasing the availability of bioactive compounds by allowing the release of these biocompounds to occur slowly over time. The use of polymers in the nanoencapsulation of active ingredients can mask the undesired physicochemical properties of the compounds to be encapsulated, thereby enhancing consumer acceptability. This covering also acts as a barrier against several foreign substances that can react with bioactive compounds and reduce their activity. Studies of the development of poly-3-hydroxybutyrate (PHB) nanocapsules from microbial sources are little explored; this review addresses the use of nanotechnology to obtain bioactive compounds coated with biopolymer nanocapsules, both obtained from Spirulina biomasses. These microalgae are Generally Recognized as Safe (GRAS) certified, which guarantees that the biomass can be used to obtain high added value biocompounds, which can be used in human and animal supplementation.