Interspecific Electron Transfer-Driven Oxytetracycline Degradation by Autotrophic Coculture of Sulfur-Oxidizing and Sulfate-Reducing Bacteria

Abstract

Interspecific electron transport (IET) can promote the cometabolism of microorganisms, so it is of great significance in environmental remediation. Herein, a coculture of autotrophic sulfur-oxidizing bacteria (SOB) and heterotrophic sulfate-reducing bacteria (SRB) was constructed to biodegrade oxytetracycline (OTC) (upgraded to 120.9 ± 3.9 μg mg–1 protein d–1) under inorganic conditions, and the biodegradation was markedly improved (1.5 times) after loading biosynthetic FeS (bio-FeS). The increase of the NAD+/NADH ratio and ATPase activity indicated that more electrons generated by intracellular metabolism inside the SOB (lacking the OTC enzyme) outflowed extracellularly to the SRB via the IET chain in the coculture system. Linear sweep voltammetry (LSV) and I–t analysis indicated that bio-FeS on the SRB could enhance direct interspecific electron transport (DIET) mainly via c-Cyts, together with the mediated interspecific electron transport (MIET) via flavins, thus accelerating the OTC efflux. Community analysis demonstrated that the SRB introduction increased the abundance of genes related to environmental information, cell motility, membrane transport, and signal transduction in the coculture system. This discovery revealed the feasibility of antibiotic degradation using heterotrophic bacteria (such as SRB) under inorganic conditions and deepened the understanding of the antibiotic degradation in biogeochemical cycles involving carbon, nitrogen, and sulfur in natural ecosystems.

Optimization of a Novel Engineered Ecosystem Integrating Carbon, Nitrogen, Phosphorus, and Sulfur Biotransformation for Saline Wastewater Treatment Using an Interpretable Machine Learning Approach

“…) to sulfate by SOB, like Thiothrix and Thiobacillus. 8 However, a higher SR concentration did not necessarily lead to a higher P removal. Therefore, a two-stage prediction was necessary to understand the relationship between SR and P removal efficiency for optimizing process performance.…”

“…Furthermore, increased ana-time promoted SR concentration by facilitating reactions between S and organic compounds (Figure h). However, in a few cases, prolonged anaerobic reaction time decreased SR due to oxidation of SR byproducts, such as sulfides or poly-S (S 0 /S n 2– ) to sulfate by SOB, like Thiothrix and Thiobacillus …”

“…Various technologies, such as sulfate reduction, autotrophic denitrification, and nitrification integrated process (SANI), elemental S-induced autotrophic denitrification, and S–limestone autotrophic denitrification, have been developed for treating saline sewage containing S. While many studies have facilitated cycling of carbon (C), S, and nitrogen (N) , improving the removal of chemical oxygen demand (COD) and total nitrogen (TN), P removal remains underexplored despite its significant role in triggering algal blooms. The recently introduced DS-EBPR (denitrifying sulfur conversion-associated enhanced biological phosphorus removal) process has promise as an innovative solution .…”

Mixed Conducting Polymers Alter Electron Transfer Thermodynamics to Boost Current Generation from Electroactive Microbes

“…One of the best-studied EAMs is Shewanella oneidensis, which has high rates of EET, oxygen tolerance, and ability to consume diverse organic substrates. , S. oneidensis is able to directly transfer electrons extracellularly through membrane-associated cytochromes but also relies on secreted mediators, mainly flavin mononucleotide (FMN) (Figure a). , These mediators also increase the distance over which electrons can be transferred and the diversity of substrates that can be used, ranging from solid metal oxides to sulfate-reducing bacteria. − Though direct electron transfer is well-studied, mediated processes have not been due to limitations in recapitulating EAM native behavior in the lab. Specifically, the reaction kinetics of mediators with the electrode are slower than most electron transfer in biological systems (Figure b,c). ,,,, …”