Biological Self-Assembled Transmembrane Electron Conduits for High-Efficiency Ammonia Production in Microbial Electrosynthesis.

Usually, CymA is irreplaceable as the electron transport hub in Shewanella oneidensis MR-1 bidirectional electron transfer. In this work, biologically self-assembled FeS nanoparticles construct an artificial electron transfer route and implement electron transfer from extracellular into periplasmic space without CymA involvement, which present similar properties to type IV pili. Bacteria are wired up into a network, and more electron transfer conduits are activated by self-assembled transmembrane FeS nanoparticles (electron conduits), thereby substantially enhancing the ammonia production. In this study, we achieved an average NH4+-N production rate of 391.8 µg·h-1·L reactor-1 with the selectivity of 98.0% and cathode efficiency of 65.4%. Additionally, the amide group in the protein-like substances located in the outer membrane was first found to be able to transfer electrons from extracellular into intracellular with c-type cytochromes. Our work provides a new viewpoint that contributes to a better understanding of the interconnections between semiconductor materials and bacteria and inspires the exploration of new electron transfer chain components.

Determinants and action paths of transboundary water pollution collaborative governance: A case study of the Yangtze River Basin, China.

With rapid economic growth, the issue of water pollution has become increasingly prominent, and there is a consensus that river basin management systems and cross-regional management coordination mechanisms need improving. In this study, 171 transboundary sections of the Yangtze River Basin were matched with the data of 57 cities to construct panel data from 2015 to 2021. Based on the four-dimensional framework of environment-determination-process-resources, the dynamic qualitative comparative analysis (QCA) method is used to identify the key influencing factors and action paths of water pollution collaborative governance effects. The results show that a single antecedent condition is not necessary to achieve efficient collaborative governance effects, and only the "number of collaborative governance" and "scale of collaboration" conditions played important roles. There are five paths that can achieve efficient collaborative governance effects: economy-oriented, ecology-oriented, technology-oriented, government-oriented, and all-oriented. Additionally, heterogeneous results show that the impact of the regional governance intention on efficient collaborative governance effect is limited in the middle and upstream sections of the Yangtze River Basin, while the downstream sections are more dependent on the basic condition of the basin. The results can help promote effective cross-regional collaboration in the Yangtze River Basin, provide scientific basis for regions to formulate targeted governance measures, and provide models for governance in other regions.

Nitrate removal by anammox bacteria utilizing photoexcited electrons via inward extracellular electron transfer channel.

Dissimilatory nitrate reduction to ammonium (DNRA) has been found to occur in some anammox bacteria species, and the DNRA metabolites (nitrite and ammonium) can further be removed to nitrogen from water. However, the activation of DNRA pathway of anammox bacteria is usually limited by the access to electron donors. Herein, we constructed a photosensitized hybrid system combining anammox bacteria (Candidatus Kuenenia stuttgartiensis and Candidatus Brocadia anammoxidans) with CdS nanoparticles semiconductor for energy-efficient NO3- removal. Such photosensitized anammox-CdS hybrid systems achieved NO3- removal with an average efficiency of 88% (the maximum of 91%) and a N2 selectivity of 72%, only with photoexcited electrons as donors. The DNRA-anammox metabolism of anammox bacteria was proved to responsible for NO3- removal via inward extracellular electron transfer channel. The greatly up-regulated genes encoding c-type cytochrome proteins (5 or 11 hemes) in the outer membrane, c-type cytochrome protein (4 hemes) and electron transport protein RnfA-E in the inner membrane, ferredoxin (2Fe-2S) in the cytoplasm and c-type cytochrome bc1 in anammoxosome membrane were supposed to play key roles in the inward extracellular electron transfer pathway. This work provides a novel insight into the design of the biotic-abiotic hybrid photosynthetic systems, and opens a new strategy for light-driven NO3- removal from the perspective of light energy input.

Light-driven ammonium oxidation to dinitrogen gas by self-photosensitized biohybrid anammox systems.

The anaerobic ammonium oxidation (anammox) process exerts a very vital role in the global nitrogen cycle (estimated to contribute 30%-50% N2 production in the oceans) and presents superiority in water/wastewater nitrogen removal performance. Until now, anammox bacteria can convert ammonium (NH4+) to dinitrogen gas (N2) with nitrite (NO2-), nitric oxide (NO), and even electrode (anode) as electron acceptors. However, it is still unclear whether anammox bacteria could utilize photoexcited holes as electron acceptors to directly oxide NH4+ to N2. Here, we constructed an anammox-cadmium sulfide nanoparticles (CdS NPs) biohybrid system. The photoinduced holes from the CdS NPs could be utilized by anammox bacteria to oxidize NH4+ to N2. 15N-isotope labeling experiments demonstrated that NH2OH instead of NO was the real intermediate. Metatranscriptomics data further proved a similar pathway for NH4+ conversion with anodes as electron acceptors. This study provides a promising and energy-efficient alternative for nitrogen removal from water/wastewater.

Possible Regulation of Larval Juvenile Hormone Titers in Bombyx mori by BmFAMeT6.

Juvenile hormone (JH) plays a vital role in the growth, development, and reproduction of insects and other arthropods. Previous experiments have suggested that BmFAMeT6 could affect the duration of the silk moth's larval stage. In this study, we established the BmFAMeT6 overexpression strain and BmFAMeT6 knockout strain using the GAL4/UAS binary hybrid system and CRISPR/Cas 9 system, respectively, and found that the larval stage of the overexpression strain was shorter, while the knockout strain was longer. Our results exhibited that both the JH titers and BmKr-h1 levels in the larvae of the third instar were reduced significantly by BmFAMeT6 overexpression, but were increased obviously by BmFAMeT6 knockout. In addition, injection of farnesoic acid induced changes in the JH I and JH II levels in the hemolymphs of larvae. This study is the first to directly reveal the role of BmFAMeT6 in the regulation of insect JH titers and the relationship between farnesoic acid and JH (JH I and JH II). This provides a new perspective on regulating the growth and development of insects such as Bombyx mori.

Superhydrophobic PVDF membrane formed by crystallization process for direct contact membrane distillation.

With growing demand for freshwater resources, membrane distillation (MD) attracts intensive attention owing to the possibility of reclaiming almost 100% freshwater with superhydrophobic membranes as the pivotal separation units. Current superhydrophobic membrane still suffers relatively complex preparation process and limited membrane flux. Herein, we developed a promising route to fabricate a high-flux superhydrophobic poly(vinylidene fluoride) (PVDF) membrane by a simple solute and solvent co-crystallization (SSCC) method, which endowed the membrane ultra-high porosity and flux. We also found that the pore size of superhydrophobic membrane can be adjusted by controlling the crystallization process of DMSO, which gave rise to membrane higher flexibility. The membrane exhibited the outperforming desalination performance even in multiple harsh environments including different temperature, salty concentration, and pH, with/without humic acid. The membrane also displayed distinguished anti-fouling performance and long-term stability, which is quite significant for practical application.

A secreted phospholipase A2 (BmsPLA2 ) regulates melanization of immunity through BmDDC in the silkworm Bombyx mori.

Insect immune-associated phospholipase A2 (PLA2 ) is an important target of pathogen invasion. Melanization, an effective defense response, has significant correlations with other immune responses to coordinate immune attack against invaders. However, the effect of PLA2 on melanization has not yet been reported in insects or other arthropods. In this work, we cloned a PLA2 gene (BmsPLA2 ), and its protein had characteristic features of secreted PLA2 (sPLA2 ). After injection of bacteria, BmsPLA2 expression and sPLA2 activity in hemolymph significantly increased. BmsPLA2 fluorescence was transferred from the cytoplasm to the cell membranes of circulating hemocytes. These results indicated that BmsPLA2 was related to hemolymph immunity in silkworms. Interestingly, reducing BmsPLA2 by RNA interference decreased melanosis (melanistic hemocytes) levels in vivo and in vitro, while BmsPLA2 overexpression had the opposite effect. The larval survival and melanization rate in the hemocoel both slowed depending on the PLA2 inhibitor dosage. These results demonstrated that BmsPLA2 plays a role in melanization during the immune process of silkworms. Surprisingly, the level of BmDDC matched the degree of melanization in various observations. BmDDC expression showed a significant increase, with the peak occurring later than that of BmsPLA2 after injection of bacteria, implying that BmsPLA2 was activated prior to BmDDC. Moreover, the alteration of BmsPLA2 by RNA interference or overexpression led to altered BmDDC levels. These results suggested that BmsPLA2 regulates the melanization response in silkworms through BmDDC. Our study proposes a new regulatory mechanism of the melanization response and new directions for understanding the complex immune networks of insects.