Improvement of biogas production and nitrogen recovery in anaerobic digestion of purple phototrophic bacteria by thermal hydrolysis.

Purple phototrophic bacteria (PPB) are a novel driver to recover organics and nutrients from wastewater by assimilative growth. Depending on the source, assimilated resources from the PPB biomass can still be recovered after a releasing step. Anaerobic digestion (AD) releases carbonand nutrients, but the release is incomplete. Thermal hydrolysis (TH) as a pretreatment before AD improves the digestibility, release, and subsequent recovery potentials. This work determines the effects of TH in batch and continuous modes regarding methane potential, nutrients' release efficiencies, volatile solids destruction, degradability, and hydrolysis rates. Continuous runs over 165 days (d) confirmed enhanced recovery potentials, achieving up to 380 LCH4/kgVS (83 % solids destruction) and 73 % N release, respectively. The TH pretreatment is energy-intensive, but with appropriate heat recovery and increased methane production in the AD of the pretreated biomass, a combined configuration is energy positive.

The integrin beta1 modulator Tirofiban prevents adipogenesis and obesity by the overexpression of integrin-linked kinase: a pre-clinical approach in vitro and in vivo.

BACKGROUND: Obesity is caused by the enlargement of the white adipose tissue (WAT) depots, characterized by the hypertrophic enlargement of malfunctioning adipocytes within WAT which increases the storage of triglycerides (TG) in the lipid droplets (LD). Adipogenesis pathways as well as the expression and activity of some extracellular matrix receptors integrins are upregulated. Integrinß1 (INTB1) is the main isoform involved in WAT remodeling during obesity and insulin resistance-related diseases. We recently described Integrin Linked Kinase (ILK), a scaffold protein recruited by INTB1, as an important mediator of WAT remodeling and insulin resistance. As the few approved drugs to fight obesity have brought long-term cardiovascular side effects and given that the consideration of INTB1 and/or ILK modulation as anti-obesogenic strategies remains unexplored, we aimed to evaluate the anti-obesogenic capacity of the clinically approved anticoagulant Tirofiban (TF), stated in preclinical studies as a cardiovascular protector. METHODS: Fully differentiated adipocytes originating from C3H10T1/2 were exposed to TF and were co-treated with specific INTB1 blockers or with siRNA-based knockdown ILK expression. Lipid-specific dyes were used to determine the TG content in LD. The genetic expression pattern of ILK, pro-inflammatory cytokines (MCP1, IL6), adipogenesis (PPARγ, Leptin), thermogenesis (UCP1), proliferation (PCNA), lipid metabolism (FASN, HSL, ATGL), and metabolite transporters (FABP4, FAT, AQP7) were detected using quantitative PCR. Cytoskeletal actin polymerization was detected by confocal microscopy. Immunoblotting was performed to detect INTB1 phosphorylation at Thr788/9 and ILK activity as phosphorylation levels of protein kinase B (AKT) in Ser473 and glycogen synthase kinase 3ß (GSK3ß) at Ser9. TF was intraperitoneally administered once per day to wildtype and ILK knockdown mice (cKDILK) challenged with a high-fat diet (HFD) or control diet (STD) for 2 weeks. Body and WAT weight gains were compared. The expression of ILK and other markers was determined in the visceral epididymal (epi) and inguinal subcutaneous (sc) WAT. RESULTS: TF reduced TG content and the expression of adipogenesis markers and transporters in adipocytes, while UCP-1 expression was increased and the expression of lipases, cytokines or PCNA was not affected. Mechanistically, TF rapidly increased and faded the intracellular phosphorylation of INTB1 but not AKT or GSK3ß. F-actin levels were rapidly decreased, and INTB1 blockade avoided the TF effect. After 24 h, ILK expression and phosphorylation rates of AKT and GSK3ß were upregulated, while ILK silencing increased TG content. INTB1 blockade and ILK silencing avoided TF effects on the TG content and the transcriptional expression of PPARγ and UCP1. In HFD-challenged mice, the systemic administration of TF for several days reduced the weight gain on WAT depots. TF reduced adipogenesis and pro-inflammatory biomarkers and increased lipolysis markers HSL and FAT in epiWAT from HFD, while increased UCP1 in scWAT. In both WATs, TF upregulated ILK expression and activity, while no changes were observed in other tissues. In HFD-fed cKDILK, the blunted ILK in epiWAT worsened weight gain and avoided the anti-obesogenic effect of in vivo TF administration. CONCLUSIONS: ILK downregulation in WAT can be considered a biomarker of obesity establishment. Via an INTB1-ILK axis, TF restores malfunctioning hypertrophied WAT by changing the expression of adipocyte-related genes, increasing ILK expression and activity, and reducing TG storage. TF prevents obesity, a property to be added to its anticoagulant and cardiovascular protective advantages.

Up-scale challenges on biopolymer production from waste streams by Purple Phototrophic Bacteria mixed cultures: A critical review.

The increasing volume of waste streams require new biological technologies that can address pollution concerns while offering sustainable products. Purple phototrophic bacteria (PPB) are very versatile organisms that present a unique metabolism that allows them to adapt to a variety of environments, including the most complex waste streams. Their successful adaptation to such demanding conditions is partly the result of internal polymers accumulation which can be stored for electron/energy balance or as carbon and nutrients reserves for deprivation periods. Polyhydroxyalkanoates, glycogen, sulphur and polyphosphate are examples of polymers produced by PPB that can be economically explored due to their applications in the plastic, energy and fertilizers sectors. Their large-scale production implies the outdoor operation of PPB systems which brings new challenges, identified in this review. An overview of the current PPB polymer producing technologies and prospects for their future development is also provided.

Safety and Tolerability of Tolvaptan in an Autosomal Dominant Polycystic Kidney Disease Spanish Cohort: A Real-World Experience.

INTRODUCTION: Autosomal dominant polycystic kidney disease (ADPKD) is the commonest inherited disorder of the kidneys. A vasopressin V2-receptor antagonist (tolvaptan) was recently approved for the treatment of ADPKD. This study aims to analyze the safety and tolerability of tolvaptan for the management of ADPKD patients in a real-world setting. METHODS: We conducted a descriptive retrospective study in ADPKD patients in an outpatient clinic setting in Spain from 2018 to 2019. Descriptive statistical analysis of demographics and clinical data, at baseline and one year after tolvaptan initiation, was assessed. Data are presented as median and interquartile range, and as frequencies for categorical variables. RESULTS: Ten patients with ADPKD were identified. At baseline median age was 49.5 (38.5-63.5) years and 60% were males. During treatment with tolvaptan, no significant aquaresis-related symptoms or hepatotoxicity were described. No serious adverse events, discontinuation, or deaths were reported during the study. CONCLUSION: Tolvaptan was well-tolerated without severe adverse events in patients with ADPKD who showed rapid disease progression criteria. Longer follow-up is required to learn about the long-term effects of this treatment.

Exploring the inhibition boundaries of mixed cultures of purple phototrophic bacteria for wastewater treatment in anaerobic conditions.

The development of novel wastewater platforms should include the analysis of the most critical functional factors including the effects of toxic or inhibitory substances. Due to the novelty of purple phototrophic bacteria (PPB)-based wastewater treatment systems, this analysis has not been done yet in mixed cultures. In this work, various relevant chemical compounds, including aromatic (phenol, 2,4,6-trichlorophenol or 246TCP, 4-nitrophenol or 4CP, sulfathiazole) and aliphatic organics (methanol, trichlorethylene or TCE, oleic acid, ethanol, propionic acid), inorganic salts (ammonium, ClO3-, Na+), and metals (Fe3+, Fe2+, Cu2+, Zn2+, Ni2+, Al3+), as well as pH, are analyzed for their effect on mixed PPB cultures in anaerobic photoheterotrophic conditions using acetate as the model organic substrate. The most toxic substances detected were 246TCP, 4NP, Cu2+, Fe2+ and Ni2+, (Ki for activity: 23 ± 2, 97 ± 12, 3.1 ± 0.4, 13 ± 3, 13 ± 1 mg/L, and Ki (or toxicity threshold) for growth: 17 ± 2, (119), 3.5 ± 0.4, (4.8), (22.9) mg/L, respectively). Some substances inhibited the activity more than the growth (sulfathiazole, Ni2+ and Fe3+), or the growth more than the activity (TCE, 4NP and Fe2+). In addition, some organic substrates, such as phenol, ethanol and propionate, specifically inhibited the acetate uptake, being noncompetitive in the case of phenol and ethanol, and most likely competitive in the case of propionate. These findings are relevant for the wastewater treatment and resource recovery applications of the PPB technology, as well as for the upgrading of current models (Photo-Anaerobic Model). In addition, the data will open possibilities to promote the production of specific compounds (as PHA or single-cell proteins) by selectively inhibiting some parts of the PPB metabolism.

Contamination of N-poor wastewater with emerging pollutants does not affect the performance of purple phototrophic bacteria and the subsequent resource recovery potential.

Propagation of emerging pollutants (EPs) in wastewater treatment plants has become a warning sign, especially for novel resource-recovery concepts. The fate of EPs on purple phototrophic bacteria (PPB)-based systems has not yet been determined. This work analyzes the performance of a photo-anaerobic membrane bioreactor treating a low-N wastewater contaminated with 25 EPs. The chemical oxygen demand (COD), N and P removal efficiencies were stable (76 ±â€¯8, 62 ±â€¯15 and 36 ±â€¯8 %, respectively) for EPs loading rate ranging from 50 to 200 ng L-1 d-1. The PPB community adapted to changes in both the EPs concentration and the organic loading rate (OLR) and maintained dominance with >85 % of total 16S gene copies. Indeed, an increment of the OLR caused an increase of the biomass growth and activity concomitantly with a higher EPs removal efficiency (30 ±â€¯13 vs 54 ±â€¯11 % removal for OLR of 307 ±â€¯4 and 590 ±â€¯8 mgCOD L-1 d-1, respectively). Biodegradation is the main mechanism of EPs removal due to low EPs accumulation on the biomass, the membrane or the reactor walls. Low EPs adsorption avoided biomass contamination, resulting in no effect on its biological methane potential. These results support the use of PPB technologies for resource recovery with low EPs contamination of the products.

Enhanced anaerobic degradability of highly polluted pesticides-bearing wastewater under thermophilic conditions.

This work presents a sustainable and cost-competitive solution for hardly biodegradable pesticides-bearing wastewater treatment in an anaerobic expanded granular sludge bed (EGSB) reactor at mesophilic (35°C) and thermophilic (55°C). The reactor was operated in continuous mode during 160days, achieving an average COD removal of 33 and 44% under mesophilic and thermophilic conditions, respectively. The increase of temperature improved the biomass activity and the production of methane by 35%. Around 96% of pesticides identified in raw wastewater were not detected in both mesophilic and thermophilic effluents. A dramatic selection of the microbial population in anaerobic granules was caused by the presence of pesticides, which also changed significantly when the temperature was increased. Pesticides caused a significant inhibition on methanogenesis, especially over acetoclastic methanogens. Aerobic biodegradability tests of the resulting anaerobic effluents revealed that aerobic post-treatment is also a feasible and effective option, yielding more than 60% COD reduction.

A mechanistic model for anaerobic phototrophs in domestic wastewater applications: Photo-anaerobic model (PAnM).

Purple phototrophic bacteria (PPB) have been recently proposed as a key potential mechanism for accumulative biotechnologies for wastewater treatment with total nutrient recovery, low greenhouse gas emissions, and a neutral to positive energy balance. Purple phototrophic bacteria have a complex metabolism which can be regulated for process control and optimization. Since microbial processes governing PPB metabolism differ from traditional processes used for wastewater treatment (e.g., aerobic and anaerobic functional groups in ASM and ADM1), a model basis has to be developed to be used as a framework for further detailed modelling under specific situations. This work presents a mixed population phototrophic model for domestic wastewater treatment in anaerobic conditions. The model includes photoheterotrophy, which is divided into acetate consumption and other organics consumption, chemoheterotrophy (including simplified fermentation and anaerobic oxidation) and photoautotrophy (using hydrogen as an electron donor), as microbial processes, as well as hydrolysis and biomass decay as biochemical processes, and is single-biomass based. The main processes have been evaluated through targeted batch experiments, and the key kinetic and stoichiometric parameters have been determined. The process was assessed by analyzing a continuous reactor simulation scenario within a long-term wastewater treatment system in a photo-anaerobic membrane bioreactor.

Wastewater sludges pretreated by different oxidation systems at mild conditions to promote the biogas formation in anaerobic processes.

The effect of different oxidation processes at mild conditions including the coupled-Fenton (sono-Fenton, photo-Fenton, and sono-photo-Fenton) and their blank systems (ultrasound, ultraviolet, zero valent iron, and Fenton) on anaerobic digestion of the sludge for biogas production was investigated. Ultrasounds led to the highest organic matter solubilization (3.8 up to 5.2 g chemical oxygen demand (COD)/L, for the raw and treated sludge, respectively), while for the rest, organic matter transformation was observed resulting in an almost soluble COD net balance. Results indicated that for the most oxidative processes, the released organic matter was probably mineralized by the hydroxyl radicals produced during the treatments. It is interesting to remark that even if the biochemical methane potential was barely enhanced by the different methods applied, all the methods demonstrated to enhance the overall kinetics of the biomethanation processes, increasing the rapidly biodegradable fraction of the sludge.

Hemoperfusión con carbón activado en intoxicación por ácido valproico. A propósito de un caso / Hemoperfusion with activated charcoal on valproic acid poisoning. A case report

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High pH (and not free ammonia) is responsible for Anammox inhibition in mildly alkaline solutions with excess of ammonium.

Ammonium is a substrate of the anaerobic ammonium oxidation (Anammox) process but it has been suggested as a substrate-inhibitor because of the action of its unionized form, free ammonia. High pH of the medium is also an important limiting factor of the Anammox bacteria. Both effects are difficult to discriminate. In this work the inhibitory effects of high pH, total ammonia (TA) and NH3 on the Anammox process were investigated simultaneously. Results confirmed that TA caused no inhibition and high pH is a much more important inhibiting factor than NH3 in mildly alkaline conditions, based on a multi-factorial analysis. Values of pH higher than 7.6 caused Anammox inhibition >10 % and should be avoided during the application of the Anammox process in practice.

Kinetics and thermodynamics of anaerobic ammonium oxidation process using Brocadia spp. dominated mixed cultures.

Anaerobic ammonium oxidation (anammox) is a recently discovered microbial process commonly applied to treat ammonium pollution in effluents with low organic carbon content. Modeling anammox processes is important for simulating and controlling full-scale plants. In this study, the anammox process was simulated using three models, and substrate and growth parameters obtained by different research groups. Two Brocadia spp.-dominated mixed cultures, one granular and the other flocculent, were used for this purpose. A very good correlation between experimental data using both sludges and model predictions was achieved by one of the models, obtaining correlation coefficients higher than 0.997. Other models and stoichiometric equations tested were unable to predict the anammox kinetics and stoichiometry. Furthermore, the thermodynamic behavior of the two mixed cultures was compared through the determination of the energy of activation of the anammox conversion at temperatures ranging from 9 to 40 °C. Optimum temperature for anammox activity was established at 30-35 °C in both cases. The energy of activation values calculated for granular sludge and flocculent sludge were 64 and 124 kJ mol(-1), respectively.

Anaerobic biodegradability of mixtures of pesticides in an expanded granular sludge bed reactor.

The biodegradability and toxicity of three commercial pesticides containing 2-methyl-4-chlorophenoxyacetic acid (MCPA), imidacloprid and dimethoate were evaluated individually, and a complex mixture of these pesticides was treated in an expanded granular sludge bed (EGSB) reactor. MCPA was partially biodegraded, while imidacloprid and dimethoate remained almost unaltered during the individual biodegradability tests. Cyclohexanone was identified as the major solvent in the dimethoate-bearing insecticide, which was completely removed regardless of the presence of other pesticides. The analysis of the inhibition over the acetoclastic methanogenesis showed IC(50) (half maximal inhibitory concentration) values of 474 and 367 mg/L for imidacloprid and dimethoate, respectively. The effect on the methanogenesis was negligible in the case of MCPA and cyclohexanone. Pesticides caused a dramatic decrease of the EGSB reactor performance. After 30 d acclimation, the EGSB reactor achieved a stable chemical oxygen demand (COD) removal efficiency and methane production of around 85% and 0.9 g CH(4)-COD/g COD, respectively, for MCPA, imidacloprid, dimethoate and cyclohexanone feed concentrations of 57, 20, 25 and 27 mg/L, respectively. The presence of complex pesticide mixtures led to synergistic/antagonistic responses, reducing the MCPA biodegradation and improving the removal of the insecticides' active ingredients, which were completely removed in the EGSB reactor.

Nitrite (not free nitrous acid) is the main inhibitor of the anammox process at common pH conditions.

Nitrite is a substrate but also an inhibitor of anaerobic ammonium oxidation (anammox).There is currently no consensus on whether ionized nitrite (INi) or free nitrous acid (FNA) is the actual inhibitor of the process. The inhibition by INi and FNA on the anammox process has been analysed using a wide range of INi and FNA concentrations and by altering the pH and total nitrite conditions. The inhibitory impacts of both species were quantified through a rational inhibition equation, considering INi and FNA as substrate inhibitor and non-competitive inhibitor, respectively. Inhibitory constants were calculated with strong statistical support as 561 mg INi-N l(-1) and 0.117 mg FNA-N l(-1). Based on the model, INi is the main inhibiting species of the anammox process at pH > 7.1, which are the most common conditions occurring in field applications of anammox.

Kinetic characterization of Brocadia spp.-dominated anammox cultures.

In this study, kinetic analyses were conducted for two Brocadia-dominated enrichment cultures, granular and flocculent, retrieved from lab-scale anaerobic ammonium oxidation (anammox) reactors. Substrate KS ranged from 0.35 to 0.69 mMN and VSmax ranged from 0.67 to 0.88 mmol Ng(-1)VSSh(-1). The model respected the experimentally measured stoichiometry of N-compounds, serving as an independent validation. Growth kinetics of the flocculent sludge was also studied, which indicates a µmax of 0.0984 d(-1) and a YX/S of 0.105 mol C-biomass mol(-1)NH4(+). The flocculent enrichment culture was used to determine the stoichiometric equation. The kinetic parameters of the Brocadia spp. cultures measured here can be used for optimizing applications of the anammox process.

Low-temperature anaerobic treatment of low-strength pentachlorophenol-bearing wastewater.

The anaerobic treatment of low-strength wastewater bearing pentachlorophenol (PCP) at psychro-mesophilic temperatures has been investigated in an expanded granular sludge bed reactor. Using an upward flow rate of 4 m h(-1), a complete removal of PCP, as well as COD removal and methanization efficiencies higher than 75% and 50%, respectively, were achieved. Methanogenesis and COD consumption were slightly affected by changes in loading rate, temperature (17-28°C) and inlet concentrations of urea and oils. Pentachlorophenol caused an irreversible inhibitory effect over both acetoclastic and hydrogenotrophic methanogens, being the later more resistant to the toxic effect of pentachlorophenol. An auto-inhibition phenomenon was observed at PCP concentrations higher than 10 mg L(-1), which was accurately predicted by a Haldane-like model. The inhibitory effect of PCP over the COD consumption and methane production was modelled by modified pseudo-Monod and Roediger models, respectively.

Integrin-linked kinase mediates the hydrogen peroxide-dependent transforming growth factor-ß1 up-regulation.

Transforming growth factor type-ß1 (TGF-ß1) has been recognized as a central mediator in many pathological events related to extracellular matrix (ECM) proteins accumulation, where their locally increased expression has been implicated in the fibrosis process of numerous organs, including glomerular fibrosis in the kidney. We and others have reported the TGF-ß1 synthesis regulation by reactive oxygen species (ROS), and moreover we also described the implication of integrin-linked kinase (ILK) in the AP-1-dependent TGF-ß1 up-regulation. Thus, we propose here that hydrogen peroxide (H2O2)-dependent TGF-ß1 regulation may be mediated by ILK activation. First we confirmed the increase in TGF-ß1 expression in human mesangial cells (HMC) after treatment with H2O2 or with an alternative H2O2-generating system such as the glucose-oxidase enzyme (GOX). By using immunoblotting, immunofluorescence, and ELISA techniques, we demonstrate that extracellular H2O2 up-regulates TGF-ß1 transcription, as well as increases TGF-ß1 promoter activity. Furthermore, catalase-decreased intracellular H2O2 abolished TGF-ß1 up-regulation. The use of pharmacological inhibitors as well as knockdown of ILK with small interfering RNA (siRNA) demonstrated the implication of a PI3K/ILK/AKT/ERK MAPK signaling pathway axis in the H2O2-induced TGF-ß1 overexpression. Finally, we explored the physiological relevance of these findings by treating HMC with angiotensin II, a known stimuli of H2O2 synthesis. Our results confirm the relevance of previous findings after a more physiological stimulus. In summary, our results provide evidence that ILK activity changes may act as a mechanism in response to different stimuli such as H2O2 in the induced TGF-ß1 up-regulation in pathological or even physiological conditions.

Inhibition of methanogenesis by chlorophenols: a kinetic approach.

Chlorophenols exert a crucial effect on the methanogenesis, considerably reducing both maximum methane potential and methanogenic rates. However, there is not enough information about the kinetic mechanism of chlorophenols toxicity on the methanogenesis, which is a key aspect for the control of the anaerobic digesters because of the sensitivity and the potential for energy recovery derived from methane release. The International Water Association-Anaerobic Digestion Model No. 1 (IWA-ADM1) can be adapted to a wide range of situations by updating or changing the equations in the model. The present study proposes a general kinetic model for methanogenesis. This model has been applied to predict the inhibition of methanogenesis by chlorophenols, and it can be used for updating the IWA-ADM1 when treating inhibitory compounds. The model was calibrated and validated using a wide broad of experimental sets of data of methane production by granular sludge in the presence of 2,4-dichlorophenol (24 DCP), 2,4,6-trichlorophenol (246TCP) and pentachlorophenol (PCP) in batch assays. A lag-phase of the effect of chlorophenols on the methanogenesis by non-adapted sludge was detected and modeled by the kinetic model proposed. In addition, the inhibitory effect of PCP was more pronounced on the acetoclastic methanogenesis than on the hydrogenotrophic one. Non-competitive and uncompetitive inhibition types were detected using 24 DCP and 246 TCP, whereas a suicide or irreversible inhibition type was observed in the case of PCP. Values of inhibition constants considerably varied depending on the chlorophenol used, between 45 mg24DCPL(-1), 41-51 mg246TCPL(-1) and 0.9-7.8 mgPCPL(-1). The higher toxicity of PCP is related with its hydrophobicity, which was determined by adsorption tests and using partition coefficients n-octanol/water. Modeling was accompanied by high statistical support in all cases, which confirmed the validation of the model proposed.

Anaerobic biodegradation of 2,4,6-trichlorophenol in expanded granular sludge bed and fluidized bed biofilm reactors bioaugmented with Desulfitobacterium spp.

The biodegradation of 2,4,6-trichlorophenol (246TCP) was studied using expanded granular sludge bed (EGSB) reactors and a fluidized bed biofilm reactor (FBBR) filled with activated carbon. One of the EGSB reactor and the FBBR were bioaugmented with Desulfitobacterium strains. 246TCP loading rate was gradually incremented from 10 to 250 mg L(-1) day(-1). The main pathway of dechlorination was in ortho-position, generating 4-chlorophenol and 2,4-dichlorophenol. The maintenance of both COD degradation efficiency (higher than 80%) and methanogenic efficiency (between 0.3 and 0.6 g CH4-COD g(-1) COD consumed) in EGSB reactor implies a great stability of the process. Through isotherm studies in FBBR, it could be deduced that around 52% of 246TCP was completely dechlorinated, whereas the adsorption involved around 16%. By means of FISH studies it was proved that the methanogenic Archaea community was maintained in the bioaugmented EGSB reactor, whereas in the FBBR this community was gradually developed until reaching stability. Desulfitobacterium community was also maintained in the reactors, although D. chlororespirans proportion rise in the FBBR at the higher 246TCP loading rates, implying that this species can withstand the 246TCP toxicity better than D. hafniense.