Stimulation and inhibition of direct interspecies electron transfer mechanisms within methanogenic reactors by adding magnetite and granular actived carbon

Advantage of conductive materials on interspecies electron transfer-independent acetoclastic methanogenesis: A critical review

“…About 4/5 of the methane rise was explained by acetoclastic methanogenesis. Evidence for the predominance of acetoclastic methanogenesis rather than DIET-CO 2 was definitively provided in the study of anaerobic soils by 13 C tracing, CH 3 F methanogenic inhibition, proteome analysis, thermodynamic analysis, electrochemical analysis, Fig. 2.…”

“…Guskos et al [29] showed that magnetite electrical conductivity reaches 2.5 × 10 2 Ω•cm − 2 , versus 2 MΩ•cm for hematite and 16 MΩ•cm for goethite. In systems involving propionate as substrate, propionate is oxidized to acetate via two possible reactions [13] (Eqs. ( 4) and ( 5)):…”

“…Biodegradation of biomass to methane is performed by hydrolytic bacteria, acid-producing bacteria, acetogenic bacteria and methanogens [5]. The efficiency of methanogenesis is controlled by syntrophic interactions between bacteria and methanogens, which have complementary metabolisms [13,39,64,124]. In particular, bacteria and methanogens share electrons using two mechanisms: transfer of small compounds, e.g.…”

Perspectives on Potential Applications of Nanometal Derivatives in Gaseous Bioenergy Pathways: Mechanisms, Life Cycle, and Toxicity

“…Additionally, NMDs were found to be able to provide functional ions that enhance microbial performance and enzymatic activity . Importantly, during DF, hydrogenase enzyme activity is boosted, thanks to a slow but significant iron release from nanosized iron oxides. − On the basis of their various merits, NMDs have been extensively employed for enhancing and accelerating the performance of AD and DF treatment systems. ,− Fruitful efforts have been dedicated in recent review articles for explaining the role played by NMDs in AD and DF. − Attention was paid to highlighting NMDs’ advantageous impact. However, full illustration for all possible NMDs–microbes reactions and the interactions between these reactions have not been synthesized yet, and this constitutes the primary objective of this review.…”

“…Extracellular electron transfer (EET) in anaerobic media is carried out either via biotic–biotic or biotic–abiotic interactions. Biotic–biotic relationships (or more specifically interspecies electron transfer: IET) refers to electron-sharing mechanisms between syntrophic microorganisms within the microbiome associated with AD. ,,, IET is subdivided into mediated and direct interspecies electron transfer (MIET and DIET). In the case of the MIET mechanism, electron transfer occurs via soluble mediators that are first generated and released by fermenting, and acidogenic bacteria diffuse in the media and are finally consumed by methanogens in a syntrophic relationship. , On the other hand, the DIET mechanism involves the exchange of electrons between microbial cells through electrical conductors located at the outer cell membrane, i.e., conductive pili (biotic nanowires), without the need for mediators. , Regarding the biotic–abiotic relationship, this relation has been categorized, based on the direction of electron flow, either as inward or outward the microbe.…”