No abstract

BackgroundIonic liquid (IL) pretreatment is receiving significant attention as a potential process that enables fractionation of lignocellulosic biomass and produces high yields of fermentable sugars suitable for the production of renewable fuels. However, successful optimization and scale up of IL pretreatment involves challenges, such as high solids loading, biomass handling and transfer, washing of pretreated solids and formation of inhibitors, which are not addressed during the development stages at the small scale in a laboratory environment. As a first in the research community, the Joint BioEnergy Institute, in collaboration with the Advanced Biofuels Process Demonstration Unit, a Department of Energy funded facility that supports academic and industrial entities in scaling their novel biofuels enabling technologies, have performed benchmark studies to identify key challenges associated with IL pretreatment using 1-ethyl-3-methylimidazolium acetate and subsequent enzymatic saccharification beyond bench scale.ResultsUsing switchgrass as the model feedstock, we have successfully executed 600-fold, relative to the bench scale (6 L vs 0.01 L), scale-up of IL pretreatment at 15% (w/w) biomass loading. Results show that IL pretreatment at 15% biomass generates a product containing 87.5% of glucan, 42.6% of xylan and only 22.8% of lignin relative to the starting material. The pretreated biomass is efficiently converted into monosaccharides during subsequent enzymatic hydrolysis at 10% loading over a 150-fold scale of operations (1.5 L vs 0.01 L) with 99.8% fermentable sugar conversion. The yield of glucose and xylose in the liquid streams were 94.8% and 62.2%, respectively, and the hydrolysate generated contains high titers of fermentable sugars (62.1 g/L of glucose and 5.4 g/L cellobiose). The overall glucan and xylan balance from pretreatment and saccharification were 95.0% and 77.1%, respectively. Enzymatic inhibition by [C2mim][OAc] at high solids loadings requires further process optimization to obtain higher yields of fermentable sugars.ConclusionResults from this initial scale up evaluation indicate that the IL-based conversion technology can be effectively scaled to larger operations and the current study establishes the first scaling parameters for this conversion pathway but several issues must be addressed before a commercially viable technology can be realized, most notably reduction in water consumption and efficient IL recycle.

The ragged (Ra) spontaneous mouse mutant is characterised by abnormalities in its coat and cardiovascular system. Four alleles are known and we have previously described mutations in the transcription factor gene Sox18 in the Ra and Ra(J) alleles. We report here Sox18 mutations in the remaining two ragged alleles, opossum (Ra(op)) and ragged-like (Ragl). The single-base deletions cause a C-terminal frameshift, abolishing transcriptional trans-activation and impairing interaction with the partner protein MEF2C. The nature of these mutations, together with the near-normal phenotype of Sox18-null mice, suggests that the ragged mutant SOX18 proteins act in a dominant-negative fashion. The four ragged mutants represent an allelic series that reveal SOX18 structure-function relationships and implicate related SOX proteins in cardiovascular and hair follicle development.

The characterisation of wine yeasts and the complex metabolic processes influencing wine fermentation and the quality of wine might best be achieved by exploiting the standard classical and recombinant genetic techniques which have been successfully used with laboratory strains. However, application of these techniques to industrial strains has been restricted because such strains are typically prototrophic and often polyploid. To overcome this problem, we have identified commercial wine strains with good mating and sporulation properties from which heterothallic derivatives were constructed by disruption of the HO gene. Consequently, these haploids are amenable to genetic analysis, whilst retaining desirable wine-making properties. The approach used was an adaptation of a previously published gene disruption procedure for laboratory yeast and is based on the acquisition of geneticin resistance from a removable KanMX marker. The present work is the first report of the application of a construct of this type to the disruption of the HO gene in wine yeasts that are in common commercial use. Most of the 4.9-kb disruption construct was successfully removed from the genome of the haploid derivative strains by loop-out of the KanMX marker through meiotic recombination. Sequencing of the HO region confirmed the reduction of foreign sequences to a 582-bp fragment comprised largely of a single direct repeat at the target gene. The removal of the active foreign gene (conferring antibiotic resistance) allows the application of other constructs based on the KanMX module without the need to resort to other selectable marker systems. Laboratory-scale fermentation trials typically showed minimal differences between the HO disruptants and the parental wine strains in terms of fermentation kinetics and formation of key metabolites.

No abstract

No abstract

No abstract

Correlated colour temperature (CCT) of a source is estimated from position in CIE 1960 colour space in relation to the black-body locus. In this paper, the methods of the ISO Guide to the Expression of Uncertainty in Measurement are applied to derive analytical expressions for uncertainty in and chromaticity coordinates and CCT, including correlation effects. Uncertainty in CCT is found by fitting the form of the black-body locus and relevant derivatives. Examples are given for calibration of four typical sources of spectral distributions. Accurate CCT is determined by a search technique. An alternative method using fitted functions to solve for CCT using the geometry in space is presented. An uncertainty in CCT of a few kelvin can be achieved.