PLZF protein forms a complex with protein TET1 to target TCF7L2 in undifferentiated spermatogonia.

The transcription factor promyelocytic leukemia zinc finger (PLZF, also known as ZBTB16) is critical for the self-renewal of spermatogonial stem cells (SSCs). However, the function of PLZF in SSCs is not clear. Here, we found that PLZF acted as an epigenetic regulator of stem cell maintenance and self-renewal of germ cells. The PLZF protein interacts with the ten-eleven translocation 1 (TET1) protein and subsequently acts as a modulator to regulate the expression of self-renewal-related genes. Furthermore, Transcription Factor 7-like 2 (TCF7L2) is promoted by the coordination of PLZF and Tri-methylation of lysine 4 on histone H3 (H3K4me3). In addition, testicular single-cell sequencing indicated that TCF7L2 is commonly expressed in the PLZF cluster. We demonstrated that PLZF directly targets TCF7L2 and alters the landscape of histone methylation in the SSCs nucleus. Meanwhile, the RD domain and Zn finger domain of PLZF synergize with H3K4me3 and directly upregulate TCF7L2 expression at the transcriptional level. Additionally, we identified a new association between PLZF and the histone methyltransferase EZH2 at the genomic level. Our study identified a new association between PLZF and H3K4me3, established the novel PLZF&TET1-H3K4me3-TCF7L2 axis at the genomic level which regulates undifferentiated spermatogonia, and provided a platform for studying germ cell development in male domestic animals.

Liquid-gas phase transition enables microbial electrolysis and H2-based membrane biofilm hybrid system to degrade organic pollution and achieve effective hydrogenotrophic denitrification of groundwater.

Electron-donor Lacking was the limiting factor for the denitrification of oligotrophic groundwater and hydrogenotrophic denitrification provided an efficient approach without secondary pollution. In this study, a hybrid system with microbial electrolysis cell (MEC) assisted hydrogen-based membrane biofilm reactor (MBfR) was established for advanced groundwater denitrification. The liquid-gas phase transition prevented the potential pollution from organic wastes in MEC to groundwater, while the bubble-free diffusion of MBfR promoted hydrogen utilization efficiency. The negative-pressure extraction from MEC and the positive pressure for gas supply into MBfR increased the hydrogen proportion and current density of MEC, and improved the kinetic constant K of the denitrification reaction in MBfR. With actual groundwater, the MEC-MBfR hybrid system achieved a nitrate reduction of 97.8% with an effluent NO3--N of 2.2 ± 1.0 mg L-1. The hydrogenotrophic denitrifiers of Thauera, Pannonibacter, and Azonexus, dominated the denitrification biofilm on the membrane and elastic filler in MBfR.

A novel approach for enhancing nitrogen and hydrogen recovery from urine in microbial electrochemical gas-permeable membrane system.

Source-separated urine is a readily accessible nutrients dense waste stream that can be used to recover nitrogen and hydrogen. In the research, the microbial electrochemical gas-permeable membrane system (MEGS) is creatively introduced for urine treatment in removing organics, recovering the total ammonia nitrogen and high-value product of hydrogen (H2) as well as ammonium sulfate ((NH4)2SO4). MEGS can simultaneously realize the functions of H2 recovery, in-situ efficient alkali production at the cathode, and the efficient absorption capacity of the gas-permeable membrane (GPM). Under the action of the urease enzyme, urea is hydrolyzed into large amounts of carbonic acid and ammonium, causing the pH (7.87 ± 0.13) and conductivity (5.44 ± 0.21 mS cm-1) of the anode to increase extremely rapidly. A large amount of NH4+ was transported to the cathode chamber under the strengthening effect of the electric field, enriched, and then absorbed to produce the high-quality (NH4)2SO4 to be recovered. The findings reveal that MEGS can achieve 100 % of urea removal, 88.52 ± 0.40 % of COD removal, 94.22 ± 2.57 % of nitrogen recovery, 0.58 ± 0.03 m3 m-3 d-1 of hydrogen yield, and 3.78 kg m-3 of (NH4)2SO4 production with 78.03 ± 3.51 % of coulombic efficiency during a 30-h cycle. A benefit of $18.29 can be achieved with the recovery of (NH4)2SO4 and H2 from 1 m3 of urine. The study presents a promising idea for the efficient nutrient-energy recovery and utilization of urine.

Simultaneous recovery of nutrients and power generation from source-separated urine based on bioelectrical coupling with the hydrophobic gas permeable tube system.

Source-separated urine has been regarded as a precious treasure on account of its rich nitrogen content and is suitable for fertilizer production. In this study, a novel bioelectrical coupling with hydrophobic gas permeable tube system (BGTS) was developed to treat urine, for removing organic matter, and recover nitrogen as value-added products in the form of nitrogen fertilizer. In the presence of the electric field, the hydrolysis process of urea in the anode chamber was accelerated, and the NH4+ driven by electric field force and concentration difference reached the cathode through the cation exchange membrane. The cathode made use of oxygen and electrons to produce alkali in situ to promote the conversion of NH4+ to NH3, which was straightforwardly absorbed in hydrophobic gas permeable tube circulating sulfuric acid solution, so as to promote the rapid migration of nitrogen and build an efficient dynamic recovery of nitrogen. After a 48-h cycle, the BGTS achieved a 95.28 ± 0.60% COD removal ratio, 91.60 ± 0.29% nitrogen recovery efficiency, and 3.48 kg m-3 ammonium sulfate fertilizer. Economic analysis indicated a profit of 5.75 $ associated with the utilization of the BGTS system for nitrogen fertilizer recovery from source separation in urine. Consequently, this study manifested that the BGTS system can recover nitrogen from human urine in a high-recovery and cost-effective way, and is of great significance in the sustainable recovery of nitrogen resources.

Tailoring spatial structure of electroactive biofilm for enhanced activity and direct electron transfer on iron phthalocyanine modified anode in microbial fuel cells.

Electroactive biofilm (EAB) has been considered as the core determining electricity generation in microbial fuel cells (MFCs), and its spatial structure regulation for enhanced activity and selectivity is of great concern. In this study, iron phthalocyanine (FePc) was introduced into a carbon cloth (CC) electrode, aiming at improving the affinity between the anode and outer membrane c-type cytochromes (OM c-Cyts) and achieving a highly active EAB. The FePc modified CC anode (FePc-CC) effectively improved the viability of EAB and enriched the Geobacter species up to 44.83% (FePc-CC) from 6.97% (CC). The FePc-CC anode achieved a much higher power density of 2419 mW m-2 than the CC (560 mW m-2) and a remarkable higher biomass loading of 2477.2 ± 84.5 µg cm-2 than the CC (749.3 ± 31.3 µg cm-2). As the charge transfer resistance was decreased by 58.6 times from 395.2 Ω (CC) to 6.74 Ω (FePc-CC), the interfacial reaction rate was accelerated and the direct electron transfer via OM c-Cyts was promoted. This work provides an effective method to improve the EAB activity by regulating its spatial structure, and opens the door toward the development of highly active EAB using metal phthalocyanines in MFCs.

Enhanced oxygen reduction activity and high-quality effluent of membrane filtration electrodes with Prussian blue in microbial fuel cells.

Membrane filtration electrode based microbial fuel cell provides a promising route to simultaneously recover energy and produce high-quality effluent during water treatment. Enhancing effluent quality and oxygen reduction reaction (ORR) activity of the membrane electrode still remains a major challenge. In this study, filtration types of membrane electrodes with Prussian blue (PB) doping and PVDF-PVC-PEG triblock copolymers were prepared by a simple phase inversion fabrication process. The PB-0.2 membrane electrode with optimal 0.2 wt% of PB obtained the highest current density (12.0 A m-2) and the lowest charge transfer resistance (5.0 ± 0.1 Ω). Rotating disk electrode (RDE) results also demonstrated that the PB-0.2 catalyst exhibited the superior ORR activity with the highest number of transferred electrons (n = 3.90). Furthermore, the MFC with PB-0.2 produced the maximum power density of 1401 ± 17 mW m-2, which was 186.5% higher than that of the control. Moreover, the filtrated effluent tCODeff was 20.6 ± 1.2 mg L-1 for the PB-0.2, which was significantly reduced by 63% compared with the control. These results showed that the addition of PB was an effective strategy to enhance the overall oxygen reduction performance and improve effluent quality of microbial fuel cells.

Boosting oxygen reduction and permeability properties of doped iron-porphyrin membrane cathode in microbial fuel cells.

To achieve a membrane cathode with excellent performance, iron-porphyrin (Fe(por)) was doped to boost the catalytic and permeability properties in microbial fuel cell (MFC). The membrane cathode with the optimal 0.05 g of Fe(por) (denoted as Fe(por)-0.05) had the highest current density of 10.3 A m-2 and the lowest charge transfer resistance of 12.6 ± 0.3 Ω. The ring-disk electrode (RDE) results further proved that the oxygen reduction reaction (ORR) occurred on the Fe(por)-0.05 through a direct four-electron transfer pathway. Moreover, the membrane cathode performed better permeability properties under electric filed and the Fe(por)-0.05 + E (E was electric field) obtained the lowest flux attenuation ratio of 14.1 ± 0.2%, which was related to its superior hydrophilicity and strong electrostatic repulsion force. Iron-porphyrin can simultaneously enhance the ORR activity and permeability of membrane cathode, providing a new direction for the practical application in MFCs.