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• The optimal concentration of CO 2 for cultivation of cyanobacterial strains was determined. • The optimal concentration of wastewater for cultivation of cyanobacteria was determined. • The fatty acid composition of lipids was studied. • The yield of dry biomass and methyl esters of Cyanobacterium sp. IPPAS B-1200 strain was determined. Current fresh water and energy shortage determines the need to study the possibilities of using living objects in bioenergy and environmental purification technologies. The development of waste-free technologies allows waste recycling, which saves raw materials and energy, in turn, reducing waste generation. The effect of different carbon dioxide concentrations and wastewater from households on the growth of cyanobacteria was studied in order to determine their capabilities in the purification processes. It was found that the optimal CO 2 concentration for the cultivation of cyanobacteria Cyanobacterium sp. IPPAS B-1200 and Desertifilum sp. IPPAS B-1220 was 10 %, and for the Cyanobacterium aponinum IPPAS B-1201 – 5%. It was revealed that the cultivation of the cyanobacterium Cyanobacterium sp. IPPASB-1200 on wastewater from the water storage reduces the concentration of organic pollutants and, accordingly, improves the physicochemical properties of water. The cleaning percentage for selected pollutants was 68–100 %. It was shown that the most optimal ratio of wastewater to nutrient media for cyanobacteria cultivation were 25:75 and 50:50. The lipid content (%/dry weight) in the biomass of the studied strains of cyanobacteria ranges from 15 to 22% after cultivation in wastewater. It was determined that the strains of Cyanobacterium genus were the most suitable for the production of biodiesel according to their fatty acids composition. It was determined that lipids were composed of only saturated and monounsaturated fatty acids. As a result of the studies, the optimal conditions for the growth of Cyanobacterium sp. IPPAS B-1200 were determined. This microorganism has a good potential to produce biodiesel as a producer of saturated and monounsaturated middle-chain-length fatty acids. [ABSTRACT FROM AUTHOR]

Recently, there has been a propensity to postpone dealing with the world's climate concerns until later, resulting in a 1.5 °C rise in temperature over the last century. Therefore, interest in biologically derived, inexhaustible energy sources based on solar energy is growing. Cyanobacteria have the potential to produce clean, renewable fuels in the form of hydrogen (H 2) gas, derived from solar energy and water. The current study reports the screening 11 cyanobacterial strains isolated from rice paddies and hotsprings for efficient H 2 producers. According to our findings, H 2 concentrations in the species ranged from 3.6 to 48.9 μmol mg−1 Chl a h−1. H 2 production by isolated species was shown to have a 2% positive influence on oxygen (O 2) and carbon dioxide (CO 2) concentrations and a 2% negative effect on all nitrogen gas (N 2) concentrations. It was discovered that at high CO 2 concentrations, photosynthesis is enhanced but H 2 production is suppressed. Anabaena variabilis BTA-1047 was found to be the most active H 2 -producing species, with an H 2 production activity of 21.3 μmol mg−1 Chl a h−1. Moreover, a 1% O 2 : 2% CO 2 gas mixture doubled the strain activity of H 2 production. The findings of the study called into the question the notion that only an anaerobic environment is required for H 2 production by N 2 -fixing cyanobacterial species and explored whether H 2 productivity can be increased by stimulating the micro-anaerobic environment with a carbon source. [Display omitted] • Eleven nitrogen fixing cyanobacteria species were isolated and identified from different ecosystems. • Four cyanobacterial strains were distinguished by nitrogenase activity and hydrogen production. • 2% CO 2 and O 2 gases influence was favorably for most strains to produce molecular hydrogen. • Supply with 1% O 2 :2% CO 2 gas ratio increased H 2 production activity in Anabaena variabilis BTA-1047 by 2-fold. [ABSTRACT FROM AUTHOR]

Increasing awareness of the harmful effects of synthetic colorants has led consumers to favor the use of natural alternatives such as plant or microbial pigments in food and cosmetics. Cyanobacteria are a rich source of many natural biopigments that are of high commercial value. In the market, bio-based pigments are usually sold as extracts to reduce purification costs. Various cell disruption methods are used for pigment extraction, such as sonication, homogenization, high pressure, supercritical CO 2 extraction, enzymatic extraction, as well as other promising novel extraction methods that make the production of cyanobacterial pigments economically viable. In addition, a continuous cultivation system is considered the most suitable cultivation mode for large-scale biomass production. However, a major limitation in the large-scale production of cyanobacterial pigments is the installation and operation costs. Thus, basic and applied research is still needed to overcome such limitations and enable cyanobacteria to enter the global market. This review focuses on various cyanobacterial pigments, their applications, and current biotechnological approaches to increase the production of biopigments for their potential use in the pharmaceutical, food, and cosmetic industries. The current state of production technologies based on either open pond systems or closed photobioreactors was compared. The potential of scientific and technological advances to increase yield and reduce production costs of cyanobacteria biomass-based pigments was also discussed. [Display omitted] • Cyanobacterial pigments (CPs) are safe and eco-friendly in comparison to synthetic ones. • CPs have commercial value due to their brilliant colors, antioxidant property and health promoting factors. • Various biotechnological approaches for optimizing CPs are considered. • The main extraction methodologies for each pigment are discussed and evaluated. [ABSTRACT FROM AUTHOR]