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Under certain conditions, cyanobacteria can switch from photosynthesis to hydrogen production, which is a good energy carrier. However, the biological diversity of hydrogen-releasing cyanobacteria has a great unexplored potential. This study is aimed to investigate the ability of new strains of cyanobacteria Cyanobacterium sp. IPPAS B-1200, Dolichospermum sp. IPPAS B-1213, and Sodalinema gerasimenkoae IPPAS B-353 to release H 2 and to evaluate the effects of photosystem II inhibitor 3-(3,4-dichlorphenyl)-1,1-dimethylurea (DCMU) on H 2 production under light and dark conditions. The results showed that cultures treated with DCMU produced several times more H 2 than untreated cells. The highest rate of H 2 photoproduction of 4.24 μmol H 2 (mg Chl a h)−1 was found in a Dolichospermum sp. IPPAS B-1213 culture treated with 20 μM DCMU. [Display omitted] • The ability of three new cyanobacterial strains to release hydrogen was studied. • The highest H2 yield was in the Dolichospermum sp. IPPAS B-1213 strain under light anaerobic conditions. • Sodalinema gerasimenkoae IPPAS B-353 released hydrogen only in the dark. • H2 production rate increased in presence of photosynthesis inhibitor. [ABSTRACT FROM AUTHOR]

The increasingly severe environmental pollution and energy shortage issues have demanded the production of renewable and sustainable biofuels to replace conventional fossil fuels. Lignocellulosic (LC) biomass as an abundant feedstock for second-generation biofuel production can help overcome the shortcomings of first-generation biofuels related to the "food versus fuel" debate and feedstock availability. Embracing the "circular bioeconomy" concept, an integrated biorefinery platform of LC biomass can be performed by employing different conversion technologies to obtain multiple valuable products. This review provides an overview of the principles and applications of thermochemical processes (pyrolysis, torrefaction, hydrothermal liquefaction, and gasification) and biochemical processes (pretreatment technologies, enzyme hydrolysis, biochemical conversion processes) involved in LC biomass biorefinery for potential biofuel applications. The engineering perspective of LC biofuel production on separate hydrolysis and fermentation (SHF), simultaneous saccharification and fermentation (SSF), simultaneous saccharification and co-fermentation (SSCF), and consolidated bioprocessing (CBP) were also discussed. [Display omitted] • Lignocellulosic biomass is an abundant feedstock for 2nd generation biofuels. • Integrated biorefinery platform of lignocellulosic biomass is designed for multiple valuable products. • Major technologies of thermochemical processing are pyrolysis and gasification. • Physical, chemical and bio-based pretreatment techniques are discussed. • Consolidated bioprocessing demonstrated huge potential in lignocellulosic biomass biorefinery. [ABSTRACT FROM AUTHOR]

Over the last five decades, solar-based hydrogen (H 2) production has been intensively studied. Specifically, the study of biophotolysis by cyanobacteria has received great attention to produce H 2 , and promising research approaches have been established. To date, numerous photobioreactors (PBRs) have been built to collect cyanobacterial biomass and generate bioenergy. Additionally, different PBR parameters were adjusted to increase the product yield. PBR development holds great potential not only for cell biomass but also for biological H 2 production. This review aimed to examine the mechanisms involved in H 2 production by cyanobacteria, explore the factors influencing the process, and describe five distinct PBRs known for their high H 2 production. This article examines the pros and cons of the most efficient PBRs for H 2 production and offers insights into strategies for increasing their productivity. [Display omitted] • Photosynthetic H 2 production processes was discussed. • Physiochemical factors affecting H 2 production were explained. • Five PBRs for H 2 production were described. • Advantages/disadvantages of PBRs used for H 2 production were described. [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]

Due to the side effects of greenhouse gases, interest in alternative energy sources is growing, and research into hydrogen (Н 2) production from cyanobacteria has become a promising direction for the industry. The article provides an overview of cyanobacterial hydrogen production strategies and their current economic efficiency. It also describes metabolic, genetic and technical methods for obtaining H 2 from cyanobacteria. Cyanobacteria are considered potential producers of hydrogen energy that will be economically viable shortly, as they only need cheap salts, water and solar energy to grow. However, producing hydrogen from cyanobacteria still requires extensive work, and the main problem is the small amount of hydrogen energy obtained. To produce large amounts of cyanobacterial hydrogen, the most active wild-type strains must be selected and technological, modular and genetic research must be carried out simultaneously. The low energy efficiency of hydrogen from cyanobacteria also shows the need for comprehensive research through international programs. [Display omitted] • This review shows hydrogen production mechanisms by cyanobacterial cells. • Importance of biohydrogen production strategies is discussed. • Cyanobacterial hydrogen production factors were analyzed. • Trends and problems for developing cyanobacterial hydrogen production is showed. [ABSTRACT FROM AUTHOR]

A limited supply of oil prompts the search for non-traditional energy sources to replace traditional ones. This makes hydrogen gas an appealing alternative source. Photosynthetic organisms capture sunlight very efficiently and convert it into organic molecules. A promising wild strain was isolated for the first time, from the rice paddies of Kazakhstan (Kyzylorda and Almaty regions), which can be considered as one of the most active hydrogen producers compared to the literature. The result showed that among the 13 isolated and collection cyanobacterial strains, Synechocystis sp. S-1 is the most active H 2 producer (2.35 μmol H 2 mg−1 Chl a h−1) in the light. In contrast, the wild-type cyanobacterium Anabaena variabilis A-1 had higher productivity, nitrogenase activity, and a stronger capacity to produce hydrogen in the dark (8.67 μmol H 2 mg−1 Chl a h−1), which matched the maximum yield obtained in the research. The metabolic modulation performed significantly increased hydrogen production. The highest photohydrogen production rate was observed in cells incubated with 25 μmol HEPES and 50 μmol sodium bicarbonate (NaHCO 3). [Display omitted] • Novel cyanobacterial strains were isolated from rice paddies and identified. • Сyanobacterial strains have been screened for productivity. • Hydrogen production by cyanobacterial strains was examined. • Strains were adapted to produce H2 optimizing their physiological properties. [ABSTRACT FROM AUTHOR]