Biosynthetic organic matters, such as humus, play important roles in iron and phosphorus cycling in soil and aquatic systems. As an important member of humus, fulvic acid (FA) is ubiquitous in different environmental media, such as water, soil, and sediments. In this study, we fabricated the network among phosphate supply, metabolism pathway of FA, iron reduction, and vivianite recovery at the batch scale. Both the vivianite recovery performance and the content of biosynthetic FA were positively related to the phosphorus dosage. The highest vivianite formation efficiency of 53% was obtained in the Fe/P = 1 batch, accompanied with the maximal iron reduction rate of 2.29 mM•day −1 , which was 2.66 times higher than that of the Fe/P = 3 batch. Simultaneously, the highest content of FA was detected in extracellular polymeric substances (EPS) of the Fe/P = 1 batch. Metabolome analysis revealed that FA biosynthesis was mainly relevant to tricarboxylic acid (TCA) cycle, amino acid metabolism, and purine metabolism, with glutamate and aspartate as the precursors. Sufficient phosphate stimulated the FA biosynthesis by modulating the biosynthesis and transformation of glutamate and aspartate. After adding 10 mg L −1 FA in Fe/P = 1 batch, the maximal iron reduction rate increase by 35%, as well as 12% improvement of the vivianite formation efficiency. Transcriptome revealed that FA promotes iron reduction and vivianite recovery by upregulating the expression of metal ion binding-, flagella-, and electron transfer activity-related genes.

No abstract

Hydrogen peroxide (H2O2)-based electrochemical advanced oxidation processes (EAOPs) have been widely attempted for various wastewater treatments. So far, stability tests of EAOPs are rarely addressed and the decay mechanism is still unclear. Here, three H2O2-based EAOP systems (electro-Fenton, photoelectro-Fenton, and photo+ electro-generated H2O2) were built for phenol degradation. More than 97% phenol was removed in all three EAOPs in 1 h at 10 mA·cm–2. As a key component in EAOPs, the cathodic H2O2 productivity is directly related to the performance of the system. We for the first time systematically investigated the decay mechanisms of the active cathode by operating the cathodes under multiple conditions over 200 h. Compared with the fresh cathode (H2O2 yield of 312 ± 22 mg·L–1·h–1 with a current efficiency of 84 ± 5% at 10 mA·cm–2), the performance of the cathode for H2O2 synthesis alone decayed by only 17.8%, whereas the H2O2 yields of cathodes operated in photoelectro-generated H2O2, electro-Fenton, and photoelectro-Fenton systems decayed by 60.0, 90.1, and 89.6%, respectively, with the synergistic effect of salt precipitation, •OH erosion, organic contamination, and optional Fe contamination. The lower current decay of 16.1–32.3% in the electrochemical tests manifested that the cathodes did not lose activity severely. Therefore, the significant decrease of H2O2 yield was because the active sites were altered to catalyze the four-electron oxygen reduction reaction, which was induced by the long-term erosion of •OH. Our findings provided new insights into cathode performance decay, offering significant information for the improvement of cathodic longevity in the future.

PKM2 is a key metabolic enzyme central to glucose metabolism and energy expenditure. Multiple stimuli regulate PKM2’s activity through allosteric modulation and post-translational modifications. Furthermore, PKM2 can partner with KDM8, an oncogenic demethylase and enter the nucleus to serve as a HIF1α co-activator. Yet, the mechanistic basis of the exon-10 region in allosteric regulation and nuclear translocation remains unclear. Here, we determined the crystal structures and kinetic coupling constants of exon-10 tumor-related mutants (H391Y and R399E), showing altered structural plasticity and reduced allostery. Immunoprecipitation analysis revealed increased interaction with KDM8 for H391Y, R399E, and G415R. We also found a higher degree of HIF1α-mediated transactivation activity, particularly in the presence of KDM8. Furthermore, overexpression of PKM2 mutants significantly elevated cell growth and migration. Together, PKM2 exon-10 mutations lead to structure-allostery alterations and increased nuclear functions mediated by KDM8 in breast cancer cells. Targeting the PKM2-KDM8 complex may provide a potential therapeutic intervention.