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Kurosawa K.,Massachusetts Institute of Technology | Radek A.,Massachusetts Institute of Technology | Radek A.,Institute of Bio and Geosciences | Plassmeier J.K.,Massachusetts Institute of Technology | Sinskey A.J.,Massachusetts Institute of Technology
Biotechnology for Biofuels

Background: Glycerol generated during renewable fuel production processes is potentially an attractive substrate for the production of value-added materials by fermentation. An engineered strain MITXM-61 of the oleaginous bacterium Rhodococcus opacus produces large amounts of intracellular triacylglycerols (TAGs) for lipid-based biofuels on high concentrations of glucose and xylose. However, on glycerol medium, MITXM-61 does not produce TAGs and grows poorly. The aim of the present work was to construct a TAG-producing R. opacus strain capable of high-cell-density cultivation at high glycerol concentrations. Results: An adaptive evolution strategy was applied to improve the conversion of glycerol to TAGs in R. opacus MITXM-61. An evolved strain, MITGM-173, grown on a defined medium with 16 g L-1 glycerol, produced 2.3 g L-1 of TAGs, corresponding to 40.4% of the cell dry weight (CDW) and 0.144 g g-1 of TAG yield per glycerol consumed. MITGM-173 was able to grow on high concentrations (greater than 150 g L-1) of glycerol. Cultivated in a medium containing an initial concentration of 20 g L-1 glycerol, 40 g L-1 glucose, and 40 g L-1 xylose, MITGM-173 was capable of simultaneously consuming the mixed substrates and yielding 13.6 g L-1 of TAGs, representing 51.2% of the CDM. In addition, when 20 g L-1 glycerol was pulse-loaded into the culture with 40 g L-1 glucose and 40 g L-1 xylose at the stationary growth phase, MITGM-173 produced 14.3 g L-1 of TAGs corresponding to 51.1% of the CDW although residual glycerol in the culture was observed. The addition of 20 g L-1 glycerol in the glucose/xylose mix resulted in a TAG yield per glycerol consumed of 0.170 g g-1 on the initial addition and 0.279 g g-1 on the pulse addition of glycerol. Conclusion: We have generated a TAG-producing R. opacus MITGM-173 strain that shows significantly improved glycerol utilization in comparison to the parental strain. The present study demonstrates that the evolved R. opacus strain shows significant promise for developing a cost-effective bioprocess to generate advanced renewable fuels from mixed sugar feedstocks supplemented with glycerol. © 2015 Kurosawa et al.; licensee BioMed Central. Source

Kienel U.,Helmholtz Center Potsdam | Vos H.,Institute for Energy Research of Germany | Dulski P.,Helmholtz Center Potsdam | Lucke A.,Institute of Bio and Geosciences | And 3 more authors.
Journal of Paleolimnology

Paleolimnological data from varved sediments in Lake Holzmaar (Eifel, Germany) were combined with documentary data on human activities, long-term data from the Historical Climate Database (HISKLID) for Germany and with recent monitoring data to evaluate changes in deposition that arose from climatic and human influences. The sediment data included seasonal layer thickness in an established varve chronology (1608-1942 AD), subannual chemical element counts, and multiannual organic matter data (TOC, TN, δ13Corg), all combined on an annual scale. Indicators for detritus deposition (lithogenic element counts and detritus layers) determined the first principal component (PC1) of the sediment data. This detritus PC1 was compared to the first PCs of the seasonal precipitation and temperature from HISKLID. While no relation was found to precipitation, the correlation with the temperature PC1 determined by spring to fall temperatures was significant. From 1608 to 1870, a positive correlation of the PCs suggests an increase of detritus deposition in the lake center with increasing non-winter temperatures. These may be linked by lake-internal sediment redeposition that increases when the periods of winter stratification become shorter and that of lake circulation longer. The detritus deposition is modulated by external detritus input depending on the intensity of erosion-conducive land use (wood pasture, wood cutting, and rotational slash-and-burn cultivation). Detritus input diminished when land use slowed down with population decrease as the consequence of plague epidemics, warfare and emigration. After 1870, forest regeneration and improving agricultural practices led to a stabilization of the catchment. Erosion and detritus deposition decreased progressively. The negative correlation of detritus deposition with the gradually increasing temperature presumably mimics a cause-effect relation, although a link with decreasing freeze-thaw action is possible. The modernization of agriculture proceeded with manuring and fertilizing, which caused an increase of lake productivity as indicated by summer blooms of diatoms with enhanced nutrient demand, increased δ13Corg values and sulfur concentrations. Within this well established data base we found combinations of criteria that may be used to deduce natural climatic or anthropogenic influences. The quantitative attribution of these influences remains a challenging task in paleolimnology because their interaction makes the detection of linking mechanisms difficult even at high degree of detail and the processes themselves remain debatable. © 2013 Springer Science+Business Media Dordrecht. Source

Jablonowski N.D.,Institute of Bio and Geosciences | Borchard N.,Julich Research Center | Zajkoska P.,Slovak University of Technology in Bratislava | Fernandez-Bayo J.D.,IRD Montpellier | And 3 more authors.
Journal of Agricultural and Food Chemistry

Biochar addition to soil has been reported to reduce the microbial degradation of pesticides due to sorption of the active compound. This study investigated whether the addition of hardwood biochar alters the mineralization of 14C-labeled atrazine in two atrazine-adapted soils from Belgium and Brazil at different moisture regimens. Biochar addition resulted in an equally high or even in a significantly higher atrazine mineralization compared to the soils without biochar. Statistical analysis revealed that the extent of atrazine mineralization was more influenced by the specific soil than by the addition of biochar. It was concluded that biochar amendment up to 5% by weight does not negatively affect the mineralization of atrazine by an atrazine-adapted soil microflora. © 2012 American Chemical Society. Source

Wasson A.,CSIRO | Bischof L.,CSIRO | Zwart A.,CSIRO | Watt M.,CSIRO | Watt M.,Institute of Bio and Geosciences
Journal of Experimental Botany

Root architecture traits are a target for pre-breeders. Incorporation of root architecture traits into new cultivars requires phenotyping. It is attractive to rapidly and directly phenotype root architecture in the field, avoiding laboratory studies that may not translate to the field. A combination of soil coring with a hydraulic push press and manual core-break counting can directly phenotype root architecture traits of depth and distribution in the field through to grain development, but large teams of people are required and labour costs are high with this method. We developed a portable fluorescence imaging system (BlueBox) to automate root counting in soil cores with image analysis software directly in the field. The lighting system was optimized to produce high-contrast images of roots emerging from soil cores. The correlation of the measurements with the root length density of the soil cores exceeded the correlation achieved by human operator measurements (R 2=0.68 versus 0.57, respectively). A BlueBox-equipped team processed 4.3 cores/hour/person, compared with 3.7 cores/hour/person for the manual method. The portable, automated in-field root architecture phenotyping system was 16% more labour efficient, 19% more accurate, and 12% cheaper than manual conventional coring, and presents an opportunity to directly phenotype root architecture in the field as part of pre-breeding programs. The platform has wide possibilities to capture more information about root health and other root traits in the field. © 2016 The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology. Source

Farlin J.,CRP Henri Tudor | Galle T.,CRP Henri Tudor | Bayerle M.,CRP Henri Tudor | Pittois D.,CRP Henri Tudor | And 6 more authors.

As a consequence of the repeated and widespread use of pesticides in agriculture, pesticide soil residues can be informative tracers of the spatial distribution of soil properties or of the application history. Atrazine, desethylatrazine and terbutylazine soil residues were measured in ninety-six soil samples taken on seventy-one contiguous fields four and a half years after the last atrazine application. The influence of soil texture and the application cycles were still clearly distinguishable in the spatial distribution of the pesticide residues. Half-lives calculated for a first order degradation kinetics from the atrazine and terbutylazine soil residues were within the range of values reported in the literature. The pesticide fate model PEARL calibrated on groundwater measurements underestimated slightly atrazine soil concentrations. The joint simulation of the fate of atrazine and its degradation product desethylatrazine also proved useful to estimate their respective half-lives and sorption parameters, and gave insight into degradation losses occurring during transport through the sandstone aquifer underlying the study site. © 2013 Elsevier B.V. Source

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