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A manganese peroxidase (MnP) isoenzyme from Panus tigrinus CBS 577.79 was produced in a benchtop stirred-tank reactor and purified to apparent homogeneity. The purification scheme involving ultrafiltration, affinity chromatography on concanavalin–A Sepharose, and gel filtration led to a purified MnP, termed “MnP II,” with a specific activity of 288 IU mg−1 protein and a final yield of 22%. The enzyme turned out to be a monomeric protein with molecular mass of 50.5 kDa, pI of 4.07, and an extent of N-glycosylation of about 5.3% of the high-mannose type. The temperature and pH optima for the formation of malonate manganic chelates were 45 °C and 5.5, respectively. MnP II proved to be poorly thermostable at 50 and 60 °C, with half-lives of 11 min and 105 s, respectively. Km values for H2O2 and Mn2+ were 16 and 124 μM, respectively. Although MnP II was able to oxidize veratryl alcohol and to catalyze the Mn2+-independent oxidation of several phenols, it cannot be assigned to the versatile peroxidase family. As opposed to versatile peroxidase oxidation, veratryl alcohol oxidation required the simultaneous presence of H2O2 and Mn2+; in addition, low turnover numbers and Km values higher than 300 μM characterized the Mn2+-independent oxidation of substituted phenols. Kinetic properties and the substrate specificity of the enzyme markedly differed from those reported for MnP isoenzymes produced by the reference strain P. tigrinus 8/18. To our knowledge, this study reports for the first time a thorough electrochemical characterization of a MnP from this fungus. [ABSTRACT FROM AUTHOR]

Abstract: This study investigated the efficiency of four different immobilised laccase preparations in the mediator-assisted oxidation of a non-phenolic lignin model compound. To this aim, Trametes villosa laccase was either covalently bound onto Eupergit® C or activated carbon, or entrapped within copper or calcium alginate. The benchmark reaction, consisting in the side-chain oxidation of 4-methoxybenzyl alcohol (4-MBA) to 4-methoxybenzaldehyde, was taken as the criterion to compare the efficiency of the immobilised laccases, and to assess the possible advantages of their use in alternative to the native enzyme. For each laccase preparation, four mediators (including HBT, HPI, VLA and TEMPO) were comparatively investigated. Comparisons were made by using the same amount of activity (i.e. 10U) for each laccase preparation, and showed that the native enzyme generally led to higher p-anisaldehyde yields than the immobilised laccases. The only exception was observed with Cu-alginate-laccase, which led to a 85% conversion of 4-MBA in the presence of HBT as the mediator. When testing the reusability of this immobilised system, a significant catalytic efficiency was maintained along three consecutive reaction cycles. [Copyright &y& Elsevier]

Fenton-like treatment (FLT) is an ISCO technique relying on the iron-induced H 2 O 2 activation in the presence of additives aimed at increasing the oxidant lifetime and maximizing iron solubility under natural soil pH conditions. The efficacy of FLT in the clean-up of hydrocarbon-contaminated soils is well established at the field-scale. However, a better assessment of the impact of the FLT on density, diversity and activity of the indigenous soil microbiota, might provide further insights into an optimal combination between FLT and in-situ bioremediation (ISB). The aim of this work was to assess the impacts of FLT on the microbial community of a diesel-contaminated soil collected nearby a gasoline station. Different FLT conditions were tested by varying either the H 2 O 2 concentrations (2 and 6%) or the oxidant application mode (single or double dosage). The impact of these treatments on the indigenous microbial community was assessed immediately after the Fenton-like treatment and after 30, 60 and 90 d and compared with enhanced natural attenuation (ENA). After FLT, a dramatic decrease in bacterial density, diversity and functionality was evident. Although in microcosms with double dosing at 2% H 2 O 2 a delayed recovery of the indigenous microbiota was observed as compared to those subjected to single oxidant dose, after 60 d incubation the respiration rate increased from 0.036 to 0.256 μg C CO 2 g −1 soil h −1 . Irrespective of the oxidant dose, best degradation results after 90 d incubation (around 80%) were observed with combined FLT, relying on double oxidant addition, and bioremediation. [ABSTRACT FROM AUTHOR]

Abstract: Paraoxonase 1 (PON1) has been suggested as a plausible candidate gene for human longevity due to its modulation of cardiovascular disease risk, by preventing oxidation of atherogenic low-density lipoprotein. The role of the PON1 192 Q/R polymorphism has been analyzed for association with survival at old age in several populations, albeit with controversial results. To reconcile the conflicting evidence, we performed a large association study with two samples of 2357 Germans and 1025 French, respectively. We combined our results with those from seven previous studies in the largest and most comprehensive meta-analysis on PON1 192 Q/R and longevity to-date, to include a total of 9580 individuals. No significant association of PON1 192 Q/R with longevity was observed, for either R allele or carriership. This finding relied on very large sample sizes, is supported by different analysis methods and is therefore considered very robust. Moreover, we have investigated a potential interaction of PON1 192 Q/R with APOE ɛ4 using data from four populations. Whereas a significant result was found in the German sample, this could not be confirmed in the other examined groups. Our large-scale meta-analysis provided no evidence that the PON1 192 Q/R polymorphism is associated with longevity, but this does not exclude the possibility of population-specific effects due to the influence of, and interaction between, different genetic and/or environmental factors (e.g. diet). [Copyright &y& Elsevier]

Abstract: The ability of stationary and shaken Lentinus tigrinus CBS 577.79 liquid cultures to degrade a mixture of polycyclic aromatic hydrocarbons (PAHs) in N-rich (i.e., malt extract glucose, MEG) and in N-limited (low-N Kirk’s medium, LNKM) media was investigated. Best results were obtained in shaken cultures where PAHs were degraded by 91% and 97% in MEG and LNKM, respectively; in stationary cultures, on the contrary, the degradation was never higher than 50%. Laccase activity was predominant on MEG while Mn-peroxidase (MnP) was preferentially produced in LNKM. The identification of degradation products showed the presence of several PAH derivatives, such as quinones, dicarboxylated and ring fission derivatives, presumably derived from the action of lignin-modifying enzymes. The presence of some degradation products (e.g., hydroxylated derivatives of anthrone and phenanthrene 9,10-dihydrodiol) suggested the possible involvement of cytochrome P-450-epoxide hydrolase system, the active form of which was found in 7-day-old cultures on MEG. In vitro experiments showed that the MnP from L. tigrinus had wider PAH substrate range and higher oxidation ability than the laccase produced by the same strain. [Copyright &y& Elsevier]