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Following the circular bioeconomy approach, this study shows the possibility of effective microalgal bioremediation of aquaculture wastewater integrated with the production of protein-rich biomass, which can be used as a feed additive. Screening was carried out among strains of Chlorella vulgaris BB-2, Parachlorella kessleri Bh-2 and Chlamydomonas reinhardtii C-124 with the aim of selecting the strain which is characterized by high indicators of growth in the fish farms wastewaters. Among these three strains, C. vulgaris BB-2 was selected due to its increased growth rate in aquaculture wastewater with ammonia, nitrite, and nitrate and phosphate removal. In addition, in the water when cultivating microalgae in it the coliform index and total microbial number decreased to 5 and 1.8 × 103 colony-forming unit cm−3. Large-scale microalgae cultivation utilizing aquaculture wastewater gave biomass production of 43.5 mg L−1 day−1. The biochemical composition analysis of the aquaculture wastewater phycoremediation-derived biomass of C. vulgaris BB-2 revealed that the content of 57.0 ± 1.2% protein, 16 ± 1.2% lipid, and 11.4 ± 1.4% carbohydrate. The obtained data indicate that the lipid extract of microalgae C. vulgaris BB-2 contained saturated 30.7% and polyunsaturated fatty acids 69.3%. The main fraction of amino acids consisted of glutamic acid, lysine, aspartic acid and leucine. The utilization of 25% microalgal biomass as a feed additive in the diet of fish has shown a positive effect on the morpho-physiological and biochemical growth parameters and intestinal microflora of Nile tilapia (Oreochromis niloticus). [ABSTRACT FROM AUTHOR]

There is currently an escalating global demand for the utilization of plant and natural extracts as pesticides due to their minimal health risks. Cyanobacteria are highly valuable organisms with significant potential in agriculture and are of great interest for the development of agrochemical agents as biopesticides. The flexibility and adaptability of Cyanobacteria to various environmental conditions are facilitated by the presence of specialized enzymes involved in the production of biologically active diverse secondary metabolites, including alkaloids, lipopolysaccharides, non-protein amino acids, non-ribosomal peptides, polyketides, terpenoids, and others. This review focuses on the metabolites synthesized from cyanobacteria that have demonstrated effectiveness as antibacterial, antiviral, antifungal agents, insecticides, herbicides, and more. The potential role of cyanobacteria as an alternative to chemical pesticides for environmental conservation is discussed. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract Biomass of high-yielding strains of phototrophic microorganisms actively accumulating lipids is a promising non-traditional raw material for bioenergy including the production of biodiesel. In this study, we present results of searching for new strains of microalgae-producers of lipids from hot springs. Within the framework of research, the primary screening of water for the presence of lipid - accumulative microalgae was carried out with the help of qualitative reaction with lipid-specific dyes, as well as 5 axenic isolates of microalgae with stable growth were identified in the laboratory and their productivity and fatty acid composition were studied. The isolated strains were identified as Chlorella vulgaris sp-1, Ankistrodesmus sp-21 , Scеnеdеsmus obliquus sp-21, Chlorella pyrenoidosa sp-13 and Chlamydomonas sp-22. The obtained data showed that the isolated strains determined by biomass in the range 1.3 g/l to 1.81 g/l. As a result of the research, it was established that the highest content of lipids was observed in the strains Chlorella vulgaris sp-1 and Scеnеdеsmus obliquus sp-21, which is 28.7 and 29.8% of the cell dry weight, respectively. The analysis of the fatty acid composition of the cells showed that the largest mass fraction of saturated and monounsaturated fatty acids was found in strain Scеnеdеsmus obliquus sp-21 - 61.9%. In the result, Scеnеdеsmus obliquus sp-21 strain isolated from thermal sources was selected as a promising candidate for biodiesel production. Highlights • 16 species of microalgae were identified in hot springs, Kazakhstan. • Scеnеdеsmus obliquus sp-21 accumulated 29.8% of lipids in the biomass. • Fatty acid composition of total lipids was suitable for biodiesel production. • Scеnеdеsmus obliquus sp-21 is promising candidate for biodiesel production. [ABSTRACT FROM AUTHOR]

Five axenic cultures of microalgae were isolated from the wastewater of Almaty city and identified as Chlorella vulgaris strain № 1, Chlorella sp. strain № 3, Scenedesmus obliquus , Phormidium foveolarum and Lyngbya limnetica . Among these strains, C. vulgaris strain № 1 was characterized by the maximum growth rate and the highest productivity. Mass cultivation of this strain in wastewater resulted in accumulation of 5 × 10 7 cells per ml in 16 days, and in the removal of ∼95% of pollutants from water. Cells of C. vulgaris consisted of ∼35% proteins, 29% carbohydrates, 30% lipids, and 6% ash, as calculated on a dry weight basis. The major fatty-acids of C. vulgaris were represented by palmitic, cis -7,10-hexadecenoic acid, linoleic, and α-linolenic acids. Culturing in wastewater decreased the unsaturation index of FAs. Thus, C. vulgaris cells are suitable for both waste water purification and accumulation of biomass for further biodiesel production. [ABSTRACT FROM AUTHOR]