Synergistic enhancement of biohydrogen production by supplementing with green synthesized magnetic iron nanoparticles using thermophilic mixed bacteria culture

The production of biohydrogen can be improved by focusing on the nutrients needed by fermentative bacteria like iron. Iron reacts with the [Fe-Fe]-hydrogenase enzyme within the mixed bacteria culture for optimum hydrogen release. Iron nanoparticles (NPs) are attractive due to its unique properties and high reactivity. It can be produced through green synthesis, a more eco-friendly and relatively lower cost process, by using iron salt as precursor and green coconut shell extracted by deep eutectic solvent (DES) as reducing agent. The coconut shell extract consists of phytochemicals that help in producing poly�disperse magnetic iron oxide nanoparticles at ~75 nm in size. The addition of optimum concentration of 200 mg Fe/L magnetic iron NPs resulted in the maximum cumulative hydrogen production, glucose utilization and hydrogen yield of 101.33 mL, 9.12 g/L and 0.79 mol H2/mol glucose respectively. Furthermore, the kinetic analysis on Gompertz model using the optimum magnetic iron NPs concentration showed that the hydrogen production potential (P) and hydrogen production rate (Rm) increased to 50.69 mL and 3.30 mL/h respectively and the lag phase time reduced about 7.12 h as compared with the control experiment (0 mg Fe/L). These results indicated the positive effects of magnetic iron NPs supplementation on fermentative biohydrogen production of mixed bacteria culture and proved the feasibility of adding the magnetic iron NPs as the micronutrient for enhancement of such hydrogen production system

Strategi pengoptimuman lanjutan untuk meningkatkan penghasilan biohidrogen foto-fermentasi oleh bakteria ungu bukan sulfur

Proses foto-fermentasi ialah suatu laluan penghasilan hidrogen yang menarik. Walau bagaimanapun, didapati bahawa kecekapan penukaran cahaya dan penghasilan biohidrogen foto-fermentasi oleh bakteria ungu bukan sulfur (PNSB) adalah sangat rendah. Maka, pelbagai pendekatan pengoptimuman telah dikaji bagi meningkatkan penghasilan fotohidrogen dan prestasi keseluruhannya. Ulasan ini membincangkan strategi pengoptimuman lanjutan untuk meningkatkan penghasilan biohidrogen foto-fermentasi secara menyeluruh. Antara strategi yang dibincangkan merangkumi pengoptimuman makronutrien dalam media penghasilan biohidrogen, faktor abiotik dan rejim pencahayaan semasa proses foto-fermentasi berlaku. Pendekatan ini menunjukkan keputusan positif dalam meningkatkan penghasilan foto-hidrogen oleh PNSB. Pendekatan gabungan yang mengintegrasikan strategi pengoptimuman individu yang berbeza dipercayai mungkin dapat mendatangkan peningkatan yang sinergistik terhadap produktiviti dan hasil biohidrogen foto-fermentasi oleh PNSB

An alternative peptone preparation using Hermetia illucens (Black soldier fly) hydrolysis: process optimization and performance evaluation

Background Hermetia illucens (HI), commonly known as the black soldier fly, has been recognized for its prowess in resource utilization and environmental protection because of its ability to transform organic waste into animal feed for livestock, poultry, and aquaculture. However, the potential of the black soldier fly’s high protein content for more than cheap feedstock is still largely unexplored. Methods This study innovatively explores the potential of H. illucens larvae (HIL) protein as a peptone substitute for microbial culture media. Four commercial proteases (alkaline protease, trypsin, trypsase, and papain) were explored to hydrolyze the defatted HIL, and the experimental conditions were optimized via response surface methodology experimental design. The hydrolysate of the defatted HIL was subsequently vacuum freeze-dried and deployed as a growth medium for three bacterial strains (Staphylococcus aureus, Bacillus subtilis, and Escherichia coli) to determine the growth kinetics between the HIL peptone and commercial peptone. Results The optimal conditions were 1.70% w/w complex enzyme (alkaline protease: trypsin at 1:1 ratio) at pH 7.0 and 54 °C for a duration of 4 h. Under these conditions, the hydrolysis of defatted HIL yielded 19.25% ±0.49%. A growth kinetic analysis showed no significant difference in growth parameters (μmax, Xmax, and λ) between the HIL peptone and commercial peptone, demonstrating that the HIL hydrolysate could serve as an effective, low-cost alternative to commercial peptone. This study introduces an innovative approach to HIL protein resource utilization, broadening its application beyond its current use in animal feed