High product specificity and production rate are regarded as key success parameters for large-scale applicability of a (bio)chemical reaction technology. Here, we report a significant performance enhancement in acetate formation from CO2, reaching comparable productivity levels as in industrial fermentation processes (volumetric production rate and product yield). A biocathode current density of -102 ± 1 A m(-2) and an acetic acid production rate of 685 ± 30 (g m(-2) day(-1)) have been achieved in this study. High recoveries of 94 ± 2% of the CO2 supplied as the sole carbon source and 100 ± 4% of electrons into the final product (acetic acid) were achieved after development of a mature biofilm, reaching an elevated product titer of up to 11 g L(-1). This high product specificity is remarkable for mixed microbial cultures, which would make the product downstream processing easier and the technology more attractive. This performance enhancement was enabled through the combination of a well-acclimatized and enriched microbial culture (very fast start-up after culture transfer), coupled with the use of a newly synthesized electrode material, EPD-3D. The throwing power of the electrophoretic deposition technique, a method suitable for large-scale production, was harnessed to form multiwalled carbon nanotube coatings onto reticulated vitreous carbon to generate a hierarchical porous structure.

Electron‐transfer pathways occurring in biocathodes are still unknown. We demonstrate here that high rates of acetate production by microbial electrosynthesis are mainly driven by an electron flux from the electrode to carbon dioxide, occurring via biologically induced hydrogen, with (99±1) % electron recovery into acetate. Nevertheless, acetate production is shown to occur exclusively within the biofilm. The acetate producers, putatively Acetoanaerobium, showed the remarkable ability to consume a high H2 flux before it could escape from the biofilm. At zero wastage of H2 gas, it allows superior production rates and lesser technical bottlenecks over technologies that rely on mass transfer of H2 to microorganisms suspended in aqueous solution. This study suggests that bacterial modification of the electrode surface (possibly via synthesis of Cu nanoparticles) is directly involved in the significant enhancement of the hydrogen production.

Resource recovery, preferably as high value products, is becoming an integral part of modern wastewater treatment, with conversion to heterotrophic or phototrophic/photosynthetic microbes a key option to minimise dissipation, and maximise recovery. This study compares the treatment capacities of purple phototrophic bacteria (PPB) and microalgae of five agri-industrial wastewaters (pork, poultry, red meat, dairy and sugar) to recover carbon, nitrogen, and phosphorous as a microbial product. The mediators have different advantages, with PPB offering moderate removals (up to 74% COD, 80% NH-N, 55% PO-P) but higher yields (>0.75 gCOD gCOD) and a more consistent, PPB dominated (>50%) product, with a higher crude protein product (>0.6 gCP gVSS). The microalgae tests achieved a better removal outcome (up to 91%COD, 91% NH-N, 73%PO-P), but with poorer quality product, and <30% abundance as algae.

A key future challenge of domestic wastewater treatment is nutrient recovery while still achieving acceptable discharge limits. Nutrient partitioning using purple phototrophic bacteria (PPB) has the potential to biologically concentrate nutrients through growth. This study evaluates the use of PPB in a continuous photo-anaerobic membrane bioreactor (PAnMBR) for simultaneous organics and nutrient removal from domestic wastewater. This process could continuously treat domestic wastewater to discharge limits (<50 mgCOD L(-1), 5 mgN L(-1), 1.0 mgP L(-1)). Approximately 6.4 ± 1.3 gNH4-N and 1.1 ± 0.2 gPO4-P for every 100 gSCOD were removed at a hydraulic retention time of 8-24 h and volumetric loading rates of 0.8-2.5 COD kg m(3) d(-1). Thus, a minimum of 200 mg L(-1) of ethanol (to provide soluble COD) was required to achieve these discharge limits. Microbial community through sequencing indicated dominance of >60% of PPB, though the PPB community was highly variable. The outcomes from the current work demonstrate the potential of PPB for continuous domestic (and possibly industrial) wastewater treatment and nutrient recovery. Technical challenges include the in situ COD supply in a continuous reactor system, as well as efficient light delivery. Addition of external (agricultural or fossil) derived organics is not financially nor environmentally justified, and carbon needs to be sourced internally from the biomass itself to enable this technology. Reduced energy consumption for lighting is technically feasible, and needs to be addressed as a key objective in scaleup.

The methanogenic degradation of oil hydrocarbons can proceed through syntrophic partnerships of hydrocarbon-degrading bacteria and methanogenic archaea [1][2][3] . However, recent culture-independent studies have suggested that the archaeon 'Candidatus Methanoliparum' alone can combine the degradation of long-chain alkanes with methanogenesis 4,5 . Here we cultured Ca. Methanoliparum from a subsurface oil reservoir. Molecular analyses revealed that Ca. Methanoliparum contains and overexpresses genes encoding alkyl-coenzyme M reductases and methyl-coenzyme M reductases, the marker genes for archaeal multicarbon alkane and methane metabolism. Incubation experiments with different substrates and mass spectrometric detection of coenzyme-M-bound intermediates confirm that Ca. Methanoliparum thrives not only on a variety of long-chain alkanes, but also on n-alkylcyclohexanes and n-alkylbenzenes with long n-alkyl (C ≥13 ) moieties. By contrast, short-chain alkanes (such as ethane to octane) or aromatics with short alkyl chains (C ≤12 ) were not consumed. The wide distribution of Ca. Methanoliparum 4-6 in oil-rich environments indicates that this alkylotrophic methanogen may have a crucial role in the transformation of hydrocarbons into methane.In subsurface oil reservoirs and marine oil seep sediments, microorganisms use hydrocarbons as a source of energy and carbon 7,8 . The microorganisms preferentially consume alkanes, cyclic and aromatic compounds, leaving an unresolved complex mixture as residue and thereby altering the quality of the oil 7,8 . In the absence of sulfate, microorganisms couple anaerobic hydrocarbon degradation to methane formation 1,9,10 . This reaction was originally demonstrated by Zengler et al 2 as methanogenic 'microbial alkane cracking', and a large number of studies have shown that it can be performed in syntrophic interactions of bacteria and archaea 11 . In this syntrophy, the bacteria ferment the oil to acetate, carbon dioxide and hydrogen, while hydrogenotrophic and/or acetotrophic methanogenic archaea use the products for methanogenesis 1,2,11 .Diverse anaerobic hydrocarbon activation mechanisms exist, including the well-studied fumarate addition pathway catalysed by glycyl radical enzymes 12 . This mechanism is widespread among bacteria that thrive on alkanes of various chain lengths and other hydrocarbons 12,13 . By contrast, several archaeal lineages activate gaseous alkanes with the help of a specific type of methyl-coenzyme M reductase (MCR), an enzyme that was originally described to catalyse the reduction of methyl-coenzyme M (methyl-CoM) to methane in methanogens 14 . Anaerobic methanotrophic archaea use canonical MCRs to activate methane into methyl-CoM, which is then oxidized to CO 2 . Short-chain alkane-oxidizing archaea contain divergent variants of this enzyme, which are known as alkyl-CoM reductases (ACRs). Analogous to the methane-activating MCR, ACRs activate multicarbon alkanes to form CoM-bound alkyl units [15][16][17] . The cultured alkane-oxidizing archaea oxidize sho...

The ecological conditions in urban area are greatly changed during the process of industrialization and urbanization of China. The pressure-state-response (PSR) framework is the most popular method to evaluate the ecological quality by integrating a set of remote sensing and statistical indicators into one index through a weighting method. However, a completely remote-sensed ecological index (RSEI), integrating normalized difference vegetation index (NDVI), Wet, land surface temperature (LST), and the normalized differential build-up and bare soil index (NDBSI) through principal components analysis (PCA) method, has been proposed to assess the regional ecological quality. The publications about urban ecological evaluation by RSEI often focus on only one city or a certain area and there are few types of research on the ecological quality assessment by RSEI of 35 major cities in China. In this paper, we employed RSEI to monitor the changes in the ecological quality in China' 35 major cities. The results of RSEI were compared to that of PSR and stepwise regression method was applied to establish the quantitative relationship among RSEI, NDVI, Wet, NDBSI, and LST. The results show that there are 18 cities with ecological quality deteriorated, mainly located in the east and southwest of China

Artificial aquaporins are synthetic molecules that mimic the structure and function of natural aquaporins (AQPs) in cell membranes. The development of artificial aquaporins would provide an alternative strategy for treatment of AQP-related diseases. In this report, an artificial aquaporin has been constructed from an amino-terminated tubular molecule, which operates in a unimolecular mechanism. The artificial channel can work in cell membranes with high water permeability and selectivity rivaling those of AQPs. Importantly, the channel can restore wound healing of the cells that contain function-lost AQPs.

Low wastewater temperatures affect microbial growth rates and microbial populations, as well as physical chemical characteristics of the wastewater. Wastewater treatment plant design needs to accommodate changing temperatures, and somewhat limited capacity is a key criticism of low strength anaerobic treatment such as Anaerobic Membrane Bioreactors (AnMBR). This study evaluates the applicability of an alternative platform utilizing purple phototrophic bacteria for low temperature domestic wastewater treatment. Two photo-anaerobic membrane bioreactors (PAnMBR) at ambient (22 °C) and low temperatures (10 °C) were compared to fully evaluate temperature response of critical processes. The results show good functionality at 10 °C in comparison with ambient operation. This enabled operation at 10 °C to discharge limits (TCOD < 100 mg L(-1); TN < 10 mg L(-1) and TP < 1 mg L(-1)) at a HRT < 1 d. While capacity of the system was not limited, microbial community showed a strong shift to a far narrower diversity, almost complete dominance by PPB, and of a single Rhodobacter spp. compared to a more diverse community in the ambient reactor. The outcomes of the current work enable applicability of PPB for domestic wastewater treatment to a broad range of regions.