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IntroductionDeveloping sustainable hydrogen production is critical for advancing renewable energy and reducing reliance on fossil fuels. Cyanobacteria, which harness solar energy through photosynthesis, provide a promising biological platform for hydrogen generation. However, improving hydrogen yields requires strategic metabolic and genetic modifications to optimize energy flow and overcome photosynthetic limitations. MethodsFour cyanobacterial species were evaluated for their hydrogen production capacities under varying experimental conditions. Photosynthesis was partially inhibited using distinct chemical inhibitors, including 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU). Exogenous glycerol was introduced as a supplementary carbon source. Hydrogen production was monitored over time, and rates were normalized to chlorophyll a content. Genomic analysis of transporter proteins was conducted to identify potential genetic loci for further enhancement of hydrogen output. ResultsNitrogen-fixingDolichospermumsp. exhibited significantly higher hydrogen production compared to the other tested species. Supplementation with glycerol notably increased both the rate and duration of hydrogen evolution, far exceeding previously established benchmarks. The maximum hydrogen production rate forDolichospermumsp. reached 132.3 μmol H₂/mg Chl a/h—representing a 30-fold enhancement over the rates observed with DCMU. Genomic screening revealed key transporter proteins with putative roles in carbon uptake and hydrogen metabolism. DiscussionThese findings underscore the potential of cyanobacteria, particularlyDolichospermumsp., as robust platforms for sustainable hydrogen production. The substantial improvements in hydrogen yield highlight the importance of targeted metabolic engineering and carbon supplementation strategies. Future work focused on optimizing identified transporter proteins and refining genetic interventions could further enhance biohydrogen efficiency. By leveraging the inherent photosynthetic machinery of cyanobacteria, this platform offers a renewable hydrogen source with significant promise for global energy sustainability. 

Biochar is a carbon-rich material prepared from the pyrolysis of biomass under various conditions. Recently, biochar drew great attention due to its promising potential in climate change mitigation, soil amendment, and environmental control. Obviously, biochar can be a beneficial soil amendment in several ways including preventing nutrients loss due to leaching, increasing N and P mineralization, and enabling the microbial mediation of N2O and CO2 emissions. However, there are also conflicting reports on biochar effects, such as water logging and weathering induced change of surface properties that ultimately affects microbial growth and soil fertility. Despite the voluminous reports on soil and biochar properties, few studies have systematically addressed the effects of biochar on the sequestration of carbon, nitrogen, and phosphorus in soils. Information on microbially-mediated transformation of carbon (C), nitrogen (N), and phosphorus (P) species in the soil environment remains relatively uncertain. A systematic documentation of how biochar influences the fate and transport of carbon, phosphorus, and nitrogen in soil is crucial to promoting biochar applications toward environmental sustainability. This report first provides an overview on the adsorption of carbon, phosphorus, and nitrogen species on biochar, particularly in soil systems. Then, the biochar-mediated transformation of organic species, and the transport of carbon, nitrogen, and phosphorus in soil systems are discussed. This review also reports on the weathering process of biochar and implications in the soil environment. Lastly, the current knowledge gaps and priority research directions for the biochar-amended systems in the future are assessed. This review focuses on literatures published in the past decade (2009–2021) on the adsorption, degradation, transport, weathering, and transformation of C, N, and P species in soil systems with respect to biochar applications.