Rehab Mostafa Mohamed

Biohydrogen (bio-H2) is a sustainable, carbon-neutral energy vector with strong potential to complement electrochemical hydrogen production. This chapter provides a critical overview of recent advances in biohydrogen generation Future developments offer avenues to reduce greenhouse gas emissions and promote a clean energy transition, as well as insights into the viability of CCS–hydrogen integrationThe chapter highlights emerging innovations in enzyme and strain engineering, immobilized photobioreactor design, and in-situ gas recovery. By combining biological insights with process intensification and techno-economic considerations, biohydrogen is positioned as a practical and decentralized pathway for renewable hydrogen production, contributing significantly to the transition toward a circular, low-carbon energy economy.

Background: The fluctuations in the growth of the thermophilic cyanobacterium Oscillatoria terebriformis population dynamics, environmental drivers, seasonal abundance, and the fluctuations in the expression of cellular proteins were recorded from sulfur water hot springs during high temperature environmental conditions. This study aimed to determine the effect of temperature on the growth of O. terebriformis . Methods: The growth curve of O. terebriformis was investigated on BG11 at the two different optimum temperatures (± 30 °C and ± 40 °C) to dissect the impact of the temperature change on growth. Furthermore, high temperature-induced cellular proteins were characterized and identified using SDS-PAGE technique and mass spectrometry analysis, respectively. Results: At the eighth day of cultivation, O . terebriformis recorded high optical density in case of both studied temperatures. Concerning the expression of the cellular proteins, several polypeptides running at approximately 120, 85, 70, 50, 35, 30, and 20 kDa were significantly upregulated downstream of the high temperature stress conditions specifically at 70 °C. Induction of protein overexpression was detected in O. terebriformis samples incubated at 70 °C (as high temperature stress). Three unique polypeptides, running at approximately 35, 30, and 20 kDa were analyzed by nano HPLC–ESI–MS/MS mass spectrometry. The first and third polypeptides were identified as biopolymer transport inner membrane (Energy transduction protein D:ExbD) protein. The second polypeptide was identified as orotate phosphoribosyl transferase (OPRT) protein. The identified proteins are involved in iron transport/heat stress response and pyrimidine biosynthesis, respectively. The High temperature-induced proteins most likely contributed to thermotolerance cascades regulating the fluctuations in O. terebriformis during temperature changes, specifically at high temperature conditions. The impact of temperature stress on the expression pattern of some O. terebriformis proteins was studied to delineate the thermotolerance underpinning seasonal temperature changes. Conclusions: The results of this study may provide a better understanding of the cellular defense mechanisms against temperature stress in cyanobacteria, specifically thermophilic O. terebriformis .

Biosorbents have demonstrated considerable potential for the remediation of metals in aqueous environments. An aqueous extract of Enteromorpha intestinalis L. (EiE) and its extract-coated silver nanoparticles have been prepared and employed for the removal of iron. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), UV-visible spectroscopy, transmission electron microscopy (TEM), gas chromatography-mass spectroscopy (GC-MS), and zeta potential were employed to characterize the prepared biosorbents. The adsorption properties of the biosorbents were investigated in batch experiments, with a range of factors taken into account, including pH, contact time, initial ion concentrations, biosorbent dosage, and temperature. A minimum-run resolution IV design (MRR-IV) was developed with the objective of optimizing the removal efficiency. The mechanisms of adsorption were investigated using both the Langmuir and Freundlich isotherms. Kinetic studies were conducted using the pseudo-first-order and pseudo-second-order models. A variety of active constituents, including organic acids, lipids, alcohols, and terpenes, were identified through the use of GC-MS, with the findings supported by FTIR spectra. Transmission electron microscopy (TEM) revealed that the nanoparticle size ranged from 5 to 44 nm, while X-ray diffraction (XRD) demonstrated a high degree of crystallinity. A screening study employing the MRR-IV methodology, facilitated by the Design-Experiment, Ver 13., indicates that three factors exert a considerable influence on the biosorption process. The study demonstrated that the biosorption mechanism is pH-dependent, with an optimal pH of 5. The adsorption performance was found to follow Freundlich isothermal models and pseudo-first-order kinetics.