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ScopeThis study was designed to evaluate the influence of ethanol on the bioavailability of blackberry anthocyanins.Methods and resultsA total of 18 participants were recruited to consume 250 mL of a blackberry puree (650 mg of anthocyanins) without (BBP) or with 12% ethanol (BBP 12%). Venous blood was collected from participants at baseline and at 15, 30, 60, and 120 min after puree ingestion. Urine samples were collected at baseline and at 120 min. Plasma and urine concentration of anthocyanins and anthocyanin conjugates were quantified by HPLC‐DAD. Methyl‐cyanidin‐glucuronide (Me‐Cy‐Glucr) and 3′‐methyl‐cyanidin‐3‐glucoside (3′‐Me‐Cy3glc) were the main anthocyanin conjugates detected in all plasma and urine samples. Urinary concentration of these anthocyanin conjugates were positively correlated with their plasma concentration. Ethanol increased plasma Cmax of Me‐Cy‐Glucr and 3′‐Me‐Cy3glc. Participants were then stratified according to their body mass index (BMI) and body fat mass. After BBP consumption, plasma Cmax of Me‐Cy‐Glucr and 3′‐Me‐Cy3glc tended to be decreased in overweight/obese participants, in comparison to normal weight participants. The increase on plasma Cmax of Me‐Cy‐Glucr and 3′‐Me‐Cy3glc induced by ethanol was more pronounced in the group of overweight/obese participants.ConclusionsEthanol seems to enhance Cy3glc metabolism that appears to be compromised in overweight and obese individuals.

Squarebop I bacteriorhodopsin is a light-activated proton pump present in the membranes of the archeon Haloquadratum walsbyi, a square-shaped organism representing 50-60% of microbial population in the crystallizer ponds of the coastal salterns. Here we describe: (1) the operating mode of a bioreactor designed to concentrate the saltern biomass through a microfiltration process based on polyethersulfone hollow fibers; (2) the isolation of Squarebop I bacteriorhodopsin from solubilized biomass by means of a single chromatographic step; (3) tightly bound lipids to the isolated and purified protein as revealed by MALDI-TOF/MS analysis; (4) the photoactivity of Squarebop I bacteriorhodopsin isolated from environmental samples by flash spectroscopy. Yield of the isolation process is 150 μg of Squarebop I bacteriorhodopsin from 1l of 25-fold concentrated biomass. The possibility of using the concentrated biomass of salterns, as renewable resource for the isolation of functional bacteriorhodopsin and possibly other valuable bioproducts, is briefly discussed.

As a fast-growing food production industry, aquaculture is dealing with the need for intensification due to the global increasing demand for fish products. However, this also implies the use of more sustainable practices to reduce negative environmental impacts currently associated with this industry, including the use of wild resources, destruction of natural ecosystems, eutrophication of effluent receiving bodies, impacts due to inadequate medication practices, among others. Using multi-species systems, such as integrated multi-trophic aquaculture, allows to produce economically important species while reducing some of these aquaculture concerns, through biomitigation of aquaculture wastes and reduction of diseases outbreaks, for example. Applying mathematical models to these systems is crucial to control and understand the interactions between species, maximizing productivity, with important environmental and economic benefits. Here, the application of some equations and models available in the literature, regarding basic parameters, is discussed – population dynamics, growth, waste production, and filtering rate – when considering the description and optimization of a theoretical integrated multi-trophic aquaculture operation composed by three trophic levels.

The recent concept of microbial electrosynthesis (MES) has evolved as an electricity-driven production technology for chemicals from low-value carbon dioxide (CO2) using micro-organisms as biocatalysts. MES from CO2 comprises bioelectrochemical reduction of CO2 to multi-carbon organic compounds using the reducing equivalents produced at the electrically-polarized cathode. The use of CO2 as a feedstock for chemicals is gaining much attention, since CO2 is abundantly available and its use is independent of the food supply chain. MES based on CO2 reduction produces acetate as a primary product. In order to elucidate the performance of the bioelectrochemical CO2 reduction process using different operation modes (batch vs. continuous), an investigation was carried out using a MES system with a flow-through biocathode supplied with 20 : 80 (v/v) or 80 : 20 (v/v) CO2 : N2 gas. The highest acetate production rate of 149 mg L−1 d−1 was observed with a 3.1 V applied cell-voltage under batch mode. While running in continuous mode, high acetate production was achieved with a maximum rate of 100 mg L−1 d−1. In the continuous mode, the acetate production was not sustained over long-term operation, likely due to insufficient microbial biocatalyst retention within the biocathode compartment (i.e. suspended micro-organisms were washed out of the system). Restarting batch mode operations resulted in a renewed production of acetate. This showed an apparent domination of suspended biocatalysts over the attached (biofilm forming) biocatalysts. Long term CO2 reduction at the biocathode resulted in the accumulation of acetate, and more reduced compounds like ethanol and butyrate were also formed. Improvements in the production rate and different biomass retention strategies (e.g. selecting for biofilm forming micro-organisms) should be investigated to enable continuous biochemical production from CO2 using MES. Certainly, other process optimizations will be required to establish MES as an innovative sustainable technology for manufacturing biochemicals from CO2 as a next generation feedstock.

Several industrial processes produce toxic sulfide containing streams that are often scrubbed using caustic solutions. An alternative, cost effective sulfide treatment method is bioelectrochemical sulfide removal. For the first time, a haloalkaliphilic sulfide-oxidizing microbial consortium was introduced to the anodic chamber of a microbial electrolysis cell operated at alkaline pH and with 1.0 M sodium ions. Under anode potential control, the highest sulfide removal rate was 2.16 mM/day and chemical analysis supported that the electrical current generation was from the sulfide oxidation. Biotic operation produced a maximum current density of 3625 mA/m2 compared to 210 mA/m2 while under abiotic operation. Furthermore, biotic electrical production was maintained for a longer period than for abiotic operation, potentially due to the passivation of the electrode by elemental sulfur during abiotic operation. The use of microorganisms reduced the energy input in this study compared to published electrochemical sulfide removal technologies. Sulfide-oxidizing populations dominated both the planktonic and electrode-attached communities with 16S rRNA gene sequences aligning within the genera Thioalkalivibrio, Thioalkalimicrobium, and Desulfurivibrio. The dominance of the Desulfurivibrio-like population on the anode surface offered evidence for the first haloalkaliphilic bacterium able to couple electrons from sulfide oxidation to extracellular electron transfer to the anode.

The kinetic parameters of anaerobic propionate degradation by biomass from 7 continuously stirred tank reactors differing in temperature, hydraulic retention time and substrate composition were investigated. In substrate-depletion experiments (batch) the maximum propionate degradation rate, Amax, and the half saturation constant, Km, were initially estimated by applying the integrated Michaelis-Menten equation. Amax was in the range from 22.8 to 29.1 micromol gVS(-1) h(-1) while Km was in the range from 0.46-0.95 mM. In general, Amax gave a good reflection of the reactor performances. Secondly, the accuracy of the applied method was evaluated by use of radiotracer methodology. Amax was found to be 14-15% lower in the substrate-depletion experiment than in the radioisotope experiment due to endogenous propionate production. By including the endogenous propionate production, a 42-49% lower Km was estimated. The results demonstrate that the rate of endogenous substrate (propionate) production should be taken into account when estimating kinetic parameters in biomass from manure-based anaerobic reactors.

Bidirectional extracellular electron transfer (EET) is mediated by back and forth electron delivery between microorganisms and extracellular substances. This enables the exchange of biochemical information and energy with the surrounding environments. As a novel bioenergy strategy, bidirectional EET provides low-cost opportunities for the production of clean energy sources and carriers (e.g., hydrogen and methane) as well as the production of value-added chemicals from carbon dioxide. Electrochemically active bacteria (EAB) can also transform pollutants to less toxic or benign substances in contaminated environments, and therefore they have been widely applied in bioremediation studies. Among all the available EAB, Geobacter and Shewanella are well-known for their versatility to accept/donate electrons from/to external environments. In this review, we focus on how these model EAB generate or harvest energy through bidirectional EET, as well as recent advances in the application of EET in bioelectrochemical technology and environmental bioremediation. Finally, the challenges, perspectives and new directions in the bidirectional EET studies are discussed. (Figure presented.).

AbstractThe effects of copper (Cu) on photosynthetic riverine biofilms were studied in artificial stream channels. Direct effects on the composition and functioning of the biofilms were investigated using plant pigments, community‐level physiological profiles (CLPP), and pulse‐amplitude‐modulated (PAM) fluorescence. Copper caused a significant reduction of microalgal biomass and induced a shift in the population from diatoms to cyanobacteria. However, a decrease in biomass indicated that the replacement of species was not totally effective to counteract the toxic effects of Cu. A direct effect of Cu could also be shown in the bacterial community, and, furthermore, changes in the CLPP could be related to the Cu treatment. Copper‐exposed biofilms lost the capacity to use between 11 and 15% of the substrates, but many of the remaining capacities became more robust, indicating an increased Cu tolerance due to the exposure. The change in the biofilm microbial composition points to the indirect effects of Cu on biofilms due to the close interdependence between biofilm autotrophic and heterotrophic compartments. Grazing by snails, which appeared to be an important factor structuring biofilms without any Cu addition, had a very minor effect on Cu‐exposed biofilms. Although grazing changed the bacterial composition, its effects were not detected either on the algal community or on the biofilm community tolerance to Cu.