Ahmadi Hikmatullah, Jalil Anam, Khan Sohail, Phulpoto Irfan Ali, Chengyu Zhang, Yu Zhisheng
College of Resources and Environment, University of Chinese Academy of Sciences, 19 A Yuquan Road, Beijing 100049, PR China.
Binzhou Institute of Technology, Weiqiao-UCAS Science and Technology Park, Binzhou City 256606 Shandong Province, PR China.
J Ind Microbiol Biotechnol. 2024 Dec 31;52. doi: 10.1093/jimb/kuaf016.
Achieving high-purity biohydrogen (Bio-H₂) production necessitates the suppression of hydrogenotrophic methanogens, as their activity can impede hydrogen yield. Various inoculum pretreatments have been employed to suppress methane-producing microorganisms; however, these methods can negatively impact the enzymatic activity of hydrogen-producing microorganisms, thereby reducing hydrogen production. To address this challenge, this research investigates a novel approach to enhance Bio-H₂ production by activating microbial enzymes using magnetite Fe₃O4-doped carbonized nanoparticles (NPs) derived from vegetable leaves (VLCFe₃O4-NPs) within a coupled dark fermentation-microbial Electrohydrogenesis system. Characterization results revealed that VLCFe₃O4-NPs exhibited cubic and spherical morphologies, with a small diameter of 1 ± 100 nm and a mean crystallite size of 38.1 nm, indicating high purity. Fermentation tests investigated the impact of different nanoparticle dosages on Bio-H₂ generation, hydrogenase gene expression (Fe-Fe and Ni-Fe), and microbial biodiversity. Bio-H₂ production significantly improved with 500 mg/L VLCFe₃O4-NPs, yielding 1.2-fold more than the control group, while even a low dose of 25 mg/L resulted in a 0.22-fold increase. Relative gene expression analysis using qPCR and the 2-ΔΔCT method demonstrated a 30-fold increase in Cbei 1773 (Fe-Fe hydrogenase) and a 23-fold increase in hucL (Ni-Fe hydrogenase) gene expression, along with an increase in 16S rDNA. Additionally, the abundance of biohydrogen-producing bacteria, Clostridium_sensu_stricto_1 and Clostridium_sensu_stricto_11, increased by 14.3% and 11.1%, respectively, compared to 4.9% and 3.9% in the control group. This research indicates that VLCFe₃O4-NPs offer an eco-friendly solution for boosting biohydrogen production within microbial electrohydrogenesis cells with dark fermentation systems, thereby supporting sustainable bioenergy generation. One-sentence summary: Green carbonized nanoparticles Fe3O4-doped have been shown to turn on the genes of bacteria (Fe-Fe and Ne-Fe) and increase the biodiversity of microbes, both of which are important for biohydrogen production.
实现高纯度生物氢（Bio-H₂）的生产需要抑制氢营养型产甲烷菌，因为它们的活性会阻碍氢气产量。人们采用了各种接种物预处理方法来抑制产甲烷微生物；然而，这些方法会对产氢微生物的酶活性产生负面影响，从而降低氢气产量。为应对这一挑战，本研究探索了一种新方法，即在耦合暗发酵-微生物电产氢系统中，使用源自蔬菜叶的磁铁矿Fe₃O₄掺杂碳化纳米颗粒（NPs，即VLCFe₃O₄-NPs）激活微生物酶，以提高Bio-H₂的产量。表征结果显示，VLCFe₃O₄-NPs呈现立方和球形形态，小直径为1±100nm，平均微晶尺寸为38.1nm，表明纯度较高。发酵试验研究了不同纳米颗粒剂量对Bio-H₂生成、氢化酶基因表达（Fe-Fe和Ni-Fe）以及微生物生物多样性的影响。添加500mg/L的VLCFe₃O₄-NPs时，Bio-H₂产量显著提高，比对照组高出1.2倍，而即使低至25mg/L的剂量也能使产量提高0.22倍。使用qPCR和2-ΔΔCT方法进行的相对基因表达分析表明，Cbei 1773（Fe-Fe氢化酶）基因表达增加了30倍，hucL（Ni-Fe氢化酶）基因表达增加了23倍，同时16S rDNA也有所增加。此外，与对照组中4.9%和3.9%相比，产氢细菌Clostridium_sensu_stricto_1和Clostridium_sensu_stricto_11的丰度分别增加了14.3%和11.1%。本研究表明，VLCFe₃O₄-NPs为在具有暗发酵系统的微生物电产氢细胞中提高生物氢产量提供了一种生态友好的解决方案，从而支持可持续生物能源的产生。一句话总结：掺杂Fe3O4的绿色碳化纳米颗粒已被证明能开启细菌基因（Fe-Fe和Ne-Fe）并增加微生物的生物多样性，这两者对生物氢生产都很重要。
