Syntrophy drives the microbial electrochemical oxidation of toluene in a continuous-flow "bioelectric well"

Microbial electrochemical technologies (MET) are promising for the remediation of groundwater pollutants such as petroleum hydrocarbons (PH). Indeed, MET can provide virtually inexhaustible electron donors or acceptors directly in the subsurface environment. However, the degradation mechanisms linking contaminants removal to electric current flow are still largely unknown, hindering the development of robust design criteria. Here, we analysed the degradation of toluene, a model PH, in a bioelectrochemical reactor known as "bioelectric well"operated in continuous-flow mode at various influent toluene concentrations. With increasing concentration of toluene, the removal rate increased while the current tended to a plateau, hence the columbic efficiency decreased. Operation at open circuit confirmed that the bioelectrochemical degradation of toluene proceeded via a syntrophic pathway involving cooperation between different microbial populations. First of all, hydrocarbon degraders quickly converted toluene into metabolic intermediates probably by breaking the aromatic ring upon fumarate addition. Subsequently, fermentative bacteria converted these intermediates into volatile fatty acids (VFA) and likely also H2, which were then used as substrates by electroactive microorganisms forming the anodic biofilm. As toluene degradation is faster than subsequent conversion steps, the increase in intermediate concentration could not result in a current increase. This work provides valuable insights on the syntrophic degradation of BTEX, which are essential for the application of microbial electrochemical system to groundwater remediation of petroleum hydrocarbons

A microcosm treatability study for evaluating wood mulch-based amendments as electron donors for trichloroethene (Tce) reductive dechlorination

In this study, wood mulch-based amendments were tested in a bench-scale microcosm experiment in order to assess the treatability of saturated soils and groundwater from an industrial site contaminated by chlorinated ethenes. Wood mulch was tested alone as the only electron donor in order to assess its potential for stimulating the biological reductive dechlorination. It was also tested in combination with millimetric iron filings in order to assess the ability of the additive to accelerate/improve the bioremediation process. The efficacy of the selected amendments was compared with that of unamended control microcosms. The results demonstrated that wood mulch is an effective natural and low-cost electron donor to stimulate the complete reductive dechlorination of chlorinated solvents to ethene. Being a side-product of the wood industry, mulch can be used in environmental remediation, an approach which perfectly fits the principles of circular economy and addresses the compelling needs of a sustainable and low environmental impact remediation. The efficacy of mulch was further improved by the co-presence of iron filings, which accelerated the conversion of vinyl chloride into the ethene by increasing the H2 availability rather than by catalyzing the direct abiotic dechlorination of contaminants. Chemical analyses were corroborated by biomolecular assays, which confirmed the stimulatory effect of the selected amendments on the abundance of Dehalococcoides mccartyi and related reductive dehalogenase genes. Overall, this paper further highlights the application potential and environmental sustainability of wood mulch-based amendments as low-cost electron donors for the biological treatment of chlorinated ethenes

Direct route from ethanol to pure hydrogen through autothermal reforming in a membrane reactor: Experimental demonstration, reactor modelling and design

This work reports the integration of thin (∼3–4 μm thick) Pd-based membranes for H2 separation in a fluidized bed catalytic reactor for ethanol auto-thermal reforming. The performance of a fluidized bed membrane reactor has been investigated from an experimental and numerical point of view. The demonstration of the technology has been carried out over 50 h under reactive conditions using 5 thin Pd-based alumina-supported membranes and a 3 wt%Pt-10 wt%Ni catalyst deposited on a mixed CeO2/SiO2 support. The results have confirmed the feasibility of the concept, in particular the capacity to reach a hydrogen recovery factor up to 70%, while the operation at different fluidization regimes, oxygen-to-ethanol and steam-to-ethanol ratios, feed pressures and reactor temperatures have been studied. The most critical part of the system is the sealing of the membranes, where most of the gas leakage was detected. A fluidized bed membrane reactor model for ethanol reforming has been developed and validated with the obtained experimental results. The model has been subsequently used to design a small reactor unit for domestic use, showing that 0.45 m2 membrane area is needed to produce the amount of H2 required for a 5 kWe PEM fuel-cell based micro-CHP system.The presented work is funded within the FluidCELL project as part of the European Union's Seventh Framework Programme (FP7/ 2007-2013) for the Fuel Cells and Hydrogen Joint Technology Initiative under grant agreement nº 621196

Hairy cell leukemia: prognosis and treatment

AIMS: To analyze clinical and laboratory features at presentation in correlation to treatment response and overall survival; evaluation of different treatment approaches. METHODS: The data of 151 consecutive HCL patients observed between 1982 and 2005 were retrospectively analyzed. RESULTS: The following data at presentation were analyzed and compared to response, DFS, PFS and OS: Hb 10,000/microl (15%); Splenomegaly (75%); Bone marrow involvement > 70% (27%). At univariate analysis only WBC > 10,000/microl resulted significantly correlated to reduced PFS. 88 Pts received as first line treatment alpha2-interferon (IFN) alone, 49 purine analogues (PA) alone or in combination with IFN, 5 were treated with splenectomy. Among IFN treated patients CR, PR and SD were obtained in 21.6%, 73.8%, 4.5% respectively of the patients; while among PA treated patients in: 26.5%, 71.4%, 2.0% respectively. DFS was significantly prolonged in patients treated with PA with respect to IFN. No significant difference in OS was observed. Median PFS was 27.6 months, median OS is projected at 238 months after a median follow up of 131 months. CONCLUSIONS: Among the routine clinical and hematochemical baseline features only the presence of WBC > 10,000/microl was correlated to a lower PFS. First line treatment with purine analogues is correlated to prolonged PFS and DFS with respect to IFN; nevertheless no difference is observed in OS

Expression of ABCC6 gene in Acute Myeloid Leukemia

Multidrug resistance (MDR) is a major impediment to the successful treatment of acute myeloid leukemia (AML). One of the known MDR mechanisms is the over expression of efflux pumps belonging to the superfamily of ABC transporters, such as P-glycoprotein (ABCB1), BCRP (ABCG2) and MRP1 (ABCC1) [1]. At present, little is known about the clinical relevance of other ABC-transporters in AML. However it was observed that patients with acute lymphoblastic leukemia presenting high MRPs expression, including MRP6, have unfavorable prognosis [2]. In this study, we investigated the expression of ABCB1, ABCC1, ABCG2 and ABCC6 genes in six healthy controls and in thirteen patients with AML, at diagnosis, after chemotherapy, at refractory disease and at relapse. Real-time PCR results showed that at diagnosis, compared to healthy subjects, all patients, except one, presented at least one among ABCB1/ABCC1/ABCC6 genes up-regulated; instead ABCG2 was always down-regulated. Moreover, we interestingly observed that three patients with poor prognosis exhibited higher level of ABCC6 mRNA after treatment compared to diagnosis and that in these patients also BCRP was up-regulated, sign of chemoresistance. We also observed that ninety percent of treated patients presented ABCG2 expression significantly higher after treatment than at diagnosis; thirty percent presented over expression of ABCB1 and only two patients showed ABCC1 up-regulation. In conclusion, our results showed a possible involvement of MRP6 in the development of MDR in AML and that BCRP has, more than MDR1 and MRP1, a relevant role in this mechanism. ABCC6 resulted up-regulated in thirty percent of treated AML patients, but further studies on a larger number of patients are necessary to establish if MRP6 may be involved in the treatment failure of AML and if co-expression of these ABC-transporters may have prognostic significance. REFERENCES 1. Brian C. Shaffer et al. Drug Resist Updat. 2012; 15(1-2): 62–69. 2. Plasschaert SL et al. Clin Cancer Res. 2005; 15;11(24 Pt 1):8661-8