Synergistic enhancement of microbes-to-pollutants and inter-microbes electron transfer by Fe, N modified ordered mesoporous biochar in anaerobic digestion.

Extracellular electron transfer was essential for degrading recalcitrant pollutants by anaerobic digestion (AD). Therefore, existing studies improved AD efficiency by enhancing the electron transfer from microbes-to-pollutants or inter-microbes. This study synthesized a novel Fe, N co-doped biochar (Fe, N-BC), which could enhance both the microbes-to-pollutants and inter-microbes electron transfer in AD. Detailed characterization data indicated that Fe, N-BC has an ordered mesoporous structure, high specific surface area (463.46 m2/g), and abundant redox functional groups (Fe2+/Fe3+, pyrrolic-N), which translate into excellent biocompatibility and electrochemical properties of Fe, N-BC. By adding Fe, N-BC, the stability and efficiency of the medium-temperature AD system in the treatment of methyl orange (MO) wastewater were improved: obtained a high degradation efficiency of MO (96.8 %) and enhanced the methane (CH4) production by 65 % compared to the control group. Meanwhile, Fe, N-BC reduced the accumulation of volatile fatty acids in the AD system, and the activity of anaerobic granular sludge electron transport system and coenzyme F420 was enhanced. In addition, Fe, N-BC showed positive enrichment of azo dyes decolorization bacteria (Georgenia) and direct interspecies electron transfer (DIET) synergistic partners (Syntrophobacter, Methanosarcina). Overall, the rapid degradation of MO and enhanced CH4 production in AD systems by Fe, N-BC is associated with enhancing two electronic pathways, i.e., microbes to MO and DIET between syntrophic bacteria and methanogenic archaea. This study introduced an enhanced "two-pathways of electron transfer" theory, realized by Fe, N-BC. These findings provided new insights into the interactions within AD systems and offer strategies for enhancing their performance with recalcitrant pollutants.

[Advances of salt stress-responsive transcription factors in plants].

Salt stress may cause primary osmotic stress and ion toxicity, as well as secondary oxidative stress and nutritional stress in plants, which hampers the agricultural production. Salt stress-responsive transcription factors can mitigate the damage of salt stress to plants through regulating the expression of downstream target genes. Based on the soil salinization and its damage to plants, and the central regulatory role of transcription factors in the plant salt stress-responsive signal transduction network, this review summarized the salt stress-responsive signal transduction pathways that the transcription factors are involved, and the application of salt stress-responsive transcription factors to enhance the salt tolerance of plants. We also reviewed the transcription factors-regulated complex downstream gene network which is formed by forming homo- or heterodimers between transcription factors and by forming complexes with regulatory proteins. This paper provides a theoretical basis for understanding the role of salt stress-responsive transcription factors in the salt stress regulatory network, which may facilitate the molecular breeding for improved stress resistance.