Growth Performance And Nutritional Value Of Scenedesmus Obliquus Cultured In Different Concentrations Of Sweetmeat Factory Waste Media

Bacterial assemblages structure in intensive cultivations of the microalga Tetradesmus obliquus

The present study shows the characterization of the bacterial communities associated with different systems during the cultivation of the microalga Tetradesmus obliquus. For that, sequential cultivation was performed in three different systems: (1) Photobioreactor bench-scale; (2) flat-panel photobioreactor; and (3) thin-layer cascade. Cultures were monitored daily for growth parameters and biomass samples were collected for characterization of bacterial communities using metagenomic. A total of 195,177 reads were produced, resulting in the identification of 72 OTUs. In the grouping of bacterial communities, 3 phyla, 6 classes, 28 families, and 35 taxa were found. The bacteria Brevundimonas and Porphyrobacter had a higher relative abundance compared with other taxa found. These taxa were present in all cultivation systems forming a possible core community. Bacterial communities associated with different cultivation systems of the microalga T. obliquus showed an increase in taxa richness and diversity in the super-intensive and intensive systems.

Stabilization of oil-water emulsions with protein concentrates from the microalga Tetradesmus obliquus

The present work used water-soluble protein concentrates from the microalga Tetradesmus obliquus to stabilize sunflower oil emulsions. Microalgal cells were disrupted by sonication, and proteins were separated from the biomass using two methods, isoelectric and solvent precipitations. The protein extracts were concentrated by lyophilization, and the concentrates were used to produce emulsions with three amounts of Tetradesmus obliquus protein concentrate (TobPC) (0.1, 0.5, and 1.0% w/v). Emulsions were homogenized through sonication and characterized for creaming index, optical microscopy, size distribution, ζ-potential, and rheology. Isoelectric precipitation resulted in TobPC with a high protein content (51.46 ± 2.37%) and a better dispersibility profile. Emulsion stability was higher for both the isoelectric TobPC and control systems than for the TobPC solvent. Solvent TobPC does not efficiently stabilize emulsions at low protein concentrations that showed microscopically larger oil droplets and flocculation spots. A high phase separation velocity was observed for solvent TobPC, probably due to the higher hydrodynamic droplet diameters. The increase in TobPC content in the emulsions resulted in more stable emulsions for all samples. Therefore, Tetradesmus obliquus protein concentrates are a potential emulsifying agent.

Integrated Approach for Carbon Sequestration and Wastewater Treatment Using Algal–Bacterial Consortia: Opportunities and Challenges

Increasing concentrations of carbon dioxide (CO2), one of the important greenhouse gases, due to combustion of fossil fuels, particularly burning coal, have become the major cause for global warming. As a consequence, many research programs on CO2 management (capture, storage, and sequestration) are being highlighted. Biological sequestration of CO2 by algae is gaining importance, as it makes use of the photosynthetic capability of these aquatic species to efficiently capture CO2 emitted from various industries and converting it into algal biomass as well as a wide range of metabolites such as polysaccharides, amino acids, fatty acids, pigments, and vitamins. In addition, their ability to thrive in rugged conditions such as seawater, contaminated lakes, and even in certain industrial wastewaters containing high organic and inorganic nutrients loads, has attracted the attention of researchers to integrate carbon capture and wastewater treatment. Algae offer a simple solution to tertiary treatments due to their nutrient removal efficiency, particularly inorganic nitrogen and phosphorus uptake. The algal–bacterial energy nexus is an important strategy capable of removing pollutants from wastewater in a synergistic manner. This review article highlights the mechanism involved in biological fixation of CO2 by microalgae, their cultivation systems, factors influencing algal cultivation in wastewater and CO2 uptake, the effect of co-cultivation of algae and bacteria in wastewater treatment systems, and challenges and opportunities.

Microalgal biomass production through phycoremediation of fresh market wastewater and potential applications as aquaculture feeds

Microalgal biomass produced from the phycoremediation of wastewater represents an important protein source, lipids, and natural antioxidants and bioproducts. Therefore, the microalgal biomass and their derived compounds are used in animal and aquaculture feed as well as human nutrition and health products. Many microalgal species have shown promising potential for many bioproducts. However, significant processes to find the optimum quality and quantity of microalgal biomass are still required especially when it is used as a replacement for aquaculture feed. The limitations lie in the selection of microalgal species and their production. The present review discusses the potential generation of bioproducts from microalgal biomass resulting from the phycoremediation of wet market wastewater. The consortium approach in wastewater treatment and the comparison between biomass production and available common feeds for aquaculture were reviewed.

Scenedesmus obliquus: Antioxidant and antiviral activity of proteins hydrolyzed by three enzymes

PURPOSE

To obtain protein hydrolysates from fresh water green algae Scenedesmus obliquus by three different enzymes and evaluate its antioxidant and antiviral activity.

METHODS

Enzymatic hydrolysates of green algae Scenedesmus obliquus protein were prepared by treatment with: 1.2% solution of pepsin, trypsin or papain. Protein was extracted from S. obliquus by three different extraction methods. Protein extracts and hydrolysates were assessed from stained gels following SDS-PAGE of samples. Antioxidant activity of protein hydrolysates was investigated.

RESULTS

S. obliquus cells and protein extracts were rich in Arg, Lys, Asp, Ala, and His. Protein hydrolyzed by papain (Sd1pa) and protein hydrolyzed by trypsin (Sd2Try) induced highest antioxidant activity based on 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical-scavenging (41.41% and 40.62%) respectively, and on 2,2'-azinobis 3-ethyl-benzothiazoline-6-sulphonate (ABTS) radical (87.03% and 45.12%) respectively, at 150 µg/ml. The inhibitory effect and mode of action of protein hydrolysates were evaluated against Coxsackie B3 virus (CVB3). Protein hydrolyzed by papain (Sd2pa) and protein hydrolyzed by pepsin (Sd1pep) at 100 µg/ml exhibited antiviral activity (66.2% and 57.6%, respectively), against (CVB3) from all protein hydrolysates.

CONCLUSION

S. obliquus protein hydrolysates have a potential as antioxidative neutraceutical ingredients and a potential therapeutic agent against CVB3.