Phthaloyl-coenzyme A decarboxylase from Thauera chlorobenzoica: the prenylated flavin-, K+ - and Fe2+ -dependent key enzyme of anaerobic phthalate degradation.

The degradation of the industrially produced and environmentally relevant phthalate esters by microorganisms is initiated by the hydrolysis to alcohols and phthalate (1,2-dicarboxybenzene). In the absence of oxygen the further degradation of phthalate proceeds via activation to phthaloyl-CoA followed by decarboxylation to benzoyl-CoA. Here, we report on the first purification and characterization of a phthaloyl-CoA decarboxylase (PCD) from the denitrifying Thauera chlorobenzoica. Hexameric PCD belongs to the UbiD-family of (de)carboxylases and contains prenylated FMN (prFMN), K+ and, unlike other UbiD-like enzymes, Fe2+ as cofactors. The latter is suggested to be involved in oxygen-independent electron-transfer during oxidative prFMN maturation. Either oxidation to the Fe3+ -state in air or removal of K+ by desalting resulted in >92% loss of both, prFMN and decarboxylation activity suggesting the presence of an active site prFMN/Fe2+ /K+ -complex in PCD. The PCD-catalysed reaction was essentially irreversible: neither carboxylation of benzoyl-CoA in the presence of 2 M bicarbonate, nor an isotope exchange of phthaloyl-CoA with 13 C-bicarbonate was observed. PCD differs in many aspects from prFMN-containing UbiD-like decarboxylases and serves as a biochemically accessible model for the large number of UbiD-like (de)carboxylases that play key roles in the anaerobic degradation of environmentally relevant aromatic pollutants.

Prediction of new-onset asthma and nasal allergy by skin prick test and RAST in a cohort of adults.

Limited information exists regarding the incidence and predictors of asthma and nasal allergy in adulthood. We determined the incidence rate of asthma and nasal allergy in adults and assessed the predictive value of skin prick tests (SPTs) and radioallergosorbent tests (RASTs) for these two outcomes. Two German centres involved in the European Community Respiratory Health Survey conducted a follow-up assessment in 2012 of the baseline participants (1185 adults aged 21-47 years assessed in 1990). The predictive value of SPTs and RASTs on new-onset asthma and nasal allergy was assessed by Cox regression and by calculating the positive or negative predictive value. During the 20 years between baseline and follow-up, 3.1 and 4.4 per 1000 person-years of new-onset asthma and nasal allergy cases were recorded, respectively. The hazard ratios for SPTs of any specific and of all aeroallergens combined were slightly higher than those of RASTs for asthma and nasal allergy. The negative predictive values of both the SPT and RAST were very high and similar (0.94-0.96), whereas the postive predictive values were low (0.09-0.20). Positive SPT results showed a better association with new onset asthma and nasal allergy than positive RAST either to any specific aeroallergens or to all combined.

Genetic Diversity of Salt Tolerance in Miscanthus.

Miscanthus is a woody rhizomatous C4 grass that can be used as a CO2 neutral biofuel resource. It has potential to grow in marginal areas such as saline soils, avoiding competition for arable lands with food crops. This study explored genetic diversity for salt tolerance in Miscanthus and discovered mechanisms and traits that can be used to improve the yield under salt stress. Seventy genotypes of Miscanthus (including 57 M. sinensis, 5 M. sacchariflorus, and 8 hybrids) were evaluated for salt tolerance under saline (150 mM NaCl) and normal growing conditions using a hydroponic system. Analyses of shoot growth traits and ion concentrations revealed the existence of large variation for salt tolerance in the genotypes. We identified genotypes with potential for high biomass production both under control and saline conditions that may be utilized for growth under marginal, saline conditions. Several relatively salt tolerant genotypes had clearly lower Na+ concentrations and showed relatively high K+/Na+ ratios in the shoots under salt stress, indicating that a Na+ exclusion mechanism was utilized to prevent Na+ accumulation in the leaves. Other genotypes showed limited reduction in leaf expansion and growth rate under saline conditions, which may be indicative of osmotic stress tolerance. The genotypes demonstrating potentially different salt tolerance mechanisms can serve as starting material for breeding programs aimed at improving salinity tolerance of Miscanthus.

Environmental Influences on the Growing Season Duration and Ripening of Diverse Miscanthus Germplasm Grown in Six Countries.

The development of models to predict yield potential and quality of a Miscanthus crop must consider climatic limitations and the duration of growing season. As a biomass crop, yield and quality are impacted by the timing of plant developmental transitions such as flowering and senescence. Growth models are available for the commercially grown clone Miscanthus x giganteus (Mxg), but breeding programs have been working to expand the germplasm available, including development of interspecies hybrids. The aim of this study was to assess the performance of diverse germplasm beyond the range of environments considered suitable for a Miscanthus crop to be grown. To achieve this, six field sites were planted as part of the EU OPTIMISC project in 2012 in a longitudinal gradient from West to East: Wales-Aberystwyth, Netherlands-Wageningen, Stuttgart-Germany, Ukraine-Potash, Turkey-Adana, and Russia-Moscow. Each field trial contained three replicated plots of the same 15 Miscanthus germplasm types. Through the 2014 growing season, phenotypic traits were measured to determine the timing of developmental stages key to ripening; the tradeoff between growth (yield) and quality (biomass ash and moisture content). The hottest site (Adana) showed an accelerated growing season, with emergence, flowering and senescence occurring before the other sites. However, the highest yields were produced at Potash, where emergence was delayed by frost and the growing season was shortest. Flowering triggers varied with species and only in Mxg was strongly linked to accumulated thermal time. Our results show that a prolonged growing season is not essential to achieve high yields if climatic conditions are favorable and in regions where the growing season is bordered by frost, delaying harvest can improve quality of the harvested biomass.

Progress on Optimizing Miscanthus Biomass Production for the European Bioeconomy: Results of the EU FP7 Project OPTIMISC.

This paper describes the complete findings of the EU-funded research project OPTIMISC, which investigated methods to optimize the production and use of miscanthus biomass. Miscanthus bioenergy and bioproduct chains were investigated by trialing 15 diverse germplasm types in a range of climatic and soil environments across central Europe, Ukraine, Russia, and China. The abiotic stress tolerances of a wider panel of 100 germplasm types to drought, salinity, and low temperatures were measured in the laboratory and a field trial in Belgium. A small selection of germplasm types was evaluated for performance in grasslands on marginal sites in Germany and the UK. The growth traits underlying biomass yield and quality were measured to improve regional estimates of feedstock availability. Several potential high-value bioproducts were identified. The combined results provide recommendations to policymakers, growers and industry. The major technical advances in miscanthus production achieved by OPTIMISC include: (1) demonstration that novel hybrids can out-yield the standard commercially grown genotype Miscanthus x giganteus; (2) characterization of the interactions of physiological growth responses with environmental variation within and between sites; (3) quantification of biomass-quality-relevant traits; (4) abiotic stress tolerances of miscanthus genotypes; (5) selections suitable for production on marginal land; (6) field establishment methods for seeds using plugs; (7) evaluation of harvesting methods; and (8) quantification of energy used in densification (pellet) technologies with a range of hybrids with differences in stem wall properties. End-user needs were addressed by demonstrating the potential of optimizing miscanthus biomass composition for the production of ethanol and biogas as well as for combustion. The costs and life-cycle assessment of seven miscanthus-based value chains, including small- and large-scale heat and power, ethanol, biogas, and insulation material production, revealed GHG-emission- and fossil-energy-saving potentials of up to 30.6 t CO2eq C ha-1y-1 and 429 GJ ha-1y-1, respectively. Transport distance was identified as an important cost factor. Negative carbon mitigation costs of -78€ t-1 CO2eq C were recorded for local biomass use. The OPTIMISC results demonstrate the potential of miscanthus as a crop for marginal sites and provide information and technologies for the commercial implementation of miscanthus-based value chains.