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Biohydrogen Production by Photobiological Processes
Published in Debabrata Das, Jhansi L. Varanasi, Fundamentals of Biofuel Production Processes, 2019
Debabrata Das, Jhansi L. Varanasi
Like pH, temperature also affects the growth rate and activity of the hydrogen-producing enzymes. An optimal temperature range of 25°C–35°C is reported for the growth of most algal species (Dasgupta et al. 2010) while for the cyanobacteria it is in the range of 30°C–40°C (Tiwari and Pandey 2012). For the thermophilic species, the optimal temperature for growth and hydrogen production can exceed 60°C. During the photobioreactor operation, the temperature deviates significantly due to the self-shading of cells. This self-shading causes loss of extra absorbed energy through the fluorescence and heat, thus leading to a rise in temperature (Dasgupta et al. 2010). Although higher temperatures offer an advantage of lower oxygen evolution, it can denature the functional proteins of the cell, thereby retarding the microbial growth. Miyamoto and others (1979) demonstrated the possibility of controlling the evolved H2/O2 ratio during biophotolysis by changing the operational temperatures. Similarly, Özgür and others (2010) showed that outdoor photobiological hydrogen production using Rhodobacter capsulatus was strongly affected by the fluctuations in temperature. They suggested that change in temperature caused the bacteria to expend their energy for adaptation to the varying temperature for their survival and in turn decreased the hydrogen yields obtained (Özgür et al. 2010). These studies implicate the necessity of maintaining controlled temperature conditions for obtaining maximum hydrogen production rates.
Biodegradable Waste: Renewable Energy Source
Published in Rouf Ahmad Bhat, Moonisa Aslam Dervash, Khalid Rehman Hakeem, Khalid Zaffar Masoodi, Environmental Biotechnology, 2022
Red photosynthetic bacteria, such as Rhodobacter sphaeroides, Rhodobacter capsulatus, Rhodovulum sulfidophilum W-1S and Rhodopseudomonas palustris have been investigated to varying degrees in hydrogen production. Following experimental research, it was found that the optimum temperature and pH for the bacteria involved in the process are known to be: for temperature, within 30°C–35°C, and for pH, pHopt = 7.0. The rate of hydrogen production varies with light intensity, carbon source, and microbial crop types.
Green hydrogen production by Rhodobacter sphaeroides
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2023
Dahbia Akroum-Amrouche, Hamza Akroum, Hakim Lounici
The defining trait of purple non-sulfur photosynthetic bacteria BPNS, such as in the genus Rhodobacter, is the ability to perform anoxygenic photosynthesis, an ancient form of photosynthesis that does not generate oxygen. Both Rhodobacter sphaeroides and Rhodobacter capsulatus have been widely studied since the 1940s (Jaschke et al. 2011) as model organisms in microbiology concerning the molecular structure of their photosynthetic apparatus, their metabolic versatility and their exceptional adaptation to growing conditions.