نانو ذرات در تولید هیدروژن بیولوژیکی Nanoparticles in Biological Hydrogen Production: An Overview

Introduction The worldwide dependence of fossil fuels as major source of energy has lead to profound negative influence on the natural environment and human health. The production of biofuels to reduce the usage of fossil fuels and if possible replace them has gained considerable attention to overcome the limitations of their fixed natural resources. The major worry is the likely hood of exhausting coal and petroleum reservoirs within the next 150–200 years [1–5]. A few potentially ecofriendly approaches have been evaluated to produce biofuels in future, which include biomethanol, biohydrogen (H2), biomethane and biodiesel [5–11]. H2 as a renewable source of energy is considered to be the cleanest and most energy efficient (122 kJ/g). The biological H2 production (BHP) at ambient physiological conditions is the most obvious and viable approach over energy intensive conventional chemical or electrochemical processes [2, 12]. The latent advantage of BHP is the potential of obtaining it from biological wastes rich in organic matter. Here, large quantum of waste generated from diverse sources especially food industry and agricultural practices seems to be a viable feedstock for BHP. It also has the advantage of effective waste management, which thus prevents further environmental pollution [1, 3, 13]. BHP can be achieved by various methods, including biophotolysis, photo-fermentation, dark-fermentation and microbial electrolysis. Among these processes, H2 production has been widely reported by phylogenetically diverse dark- and photo-fermentative microorganisms [2, 9]. This search for novel H2 producers has been aided by screening of strains isolated from the diverse environmental habitats and comparative genomic techniques. These studies have enabled identification of strains with high H2 producing potential [14, 15]. Microbial H2 production is influences by physiological factors, such as pH, feed, temperature, and type of inoculum [9, 16].