BackgroundHigh-temperature fermentation technology with thermotolerant microbes has been expected to reduce the cost of bioconversion of cellulosic biomass to fuels or chemicals. Thermotolerant Kluyveromyces marxianus possesses intrinsic abilities to ferment and assimilate a wide variety of substrates including xylose and to efficiently produce proteins. These capabilities have been found to exceed those of the traditional ethanol producer Saccharomyces cerevisiae or lignocellulose-bioconvertible ethanologenic Scheffersomyces stipitis.ResultsThe complete genome sequence of K. marxianus DMKU 3-1042 as one of the most thermotolerant strains in the same species has been determined. A comparison of its genomic information with those of other yeasts and transcriptome analysis revealed that the yeast bears beneficial properties of temperature resistance, wide-range bioconversion ability, and production of recombinant proteins. The transcriptome analysis clarified distinctive metabolic pathways under three different growth conditions, static culture, high temperature, and xylose medium, in comparison to the control condition of glucose medium under a shaking condition at 30°C. Interestingly, the yeast appears to overcome the issue of reactive oxygen species, which tend to accumulate under all three conditions.ConclusionsThis study reveals many gene resources for the ability to assimilate various sugars in addition to species-specific genes in K. marxianus, and the molecular basis of its attractive traits for industrial applications including high-temperature fermentation. Especially, the thermotolerance trait may be achieved by an integrated mechanism consisting of various strategies. Gene resources and transcriptome data of the yeast are particularly useful for fundamental and applied researches for innovative applications.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-015-0227-x) contains supplementary material, which is available to authorized users.

Ethanol fermentation ability of the thermotolerant yeast Kluyveromyces marxianus, which is able to utilize various sugars including glucose, mannose, galactose, xylose, and arabinose, was examined under shaking and static conditions at high temperatures. The yeast was found to produce ethanol from all of these sugars except for arabinose under a shaking condition but only from hexose sugars under a static condition. Growth and sugar utilization rate under a static condition were slower than those under a shaking condition, but maximum ethanol yield was slightly higher. Even at 40°C, a level of ethanol production similar to that at 30°C was observed except for galactose under a static condition. Glucose repression on utilization of other sugars was observed, and it was more evident at elevated temperatures. Consistent results were obtained by the addition of 2-deoxyglucose. The glucose effect was further examined at a transcription level, and it was found that KmGAL1 for galactokinase and KmXYL1 for xylose reductase for galactose and xylose/arabinose utilization, respectively, were repressed by glucose at low and high temperatures, but KmHXK2 for hexokinase was not repressed. We discuss the possible mechanism of glucose repression and the potential for utilization of K. marxianus in high-temperature fermentation with mixed sugars containing glucose.

Grain protein concentration (GPC) is one of the most important factors influencing pasta-making quality. Durum wheat (Triticum turgidum L. var durum) cultivars with high GPC produce pasta with increased tolerance to overcooking and greater cooked firmness. However, the large environmental effect on expression of GPC and the negative correlation with grain yield have slowed genetic improvement of this important trait. Understanding the genetics and identification of molecular markers associated with high GPC would aid durum wheat breeders in trait selection at earlier generations. The objectives of this study were to identify and validate molecular markers associated with quantitative trait loci (QTL) for elevated GPC in durum wheat. A genetic map was constructed using SSR and DArT markers in an F(1)-derived doubled haploid (DH) population derived from the cross DT695 x Strongfield. The GPC data were collected from replicated trials grown in six Canadian environments from 2002 to 2005. QTL associated with variation for GPC were identified on the group 1, 2, and 7 chromosomes and on 5B and 6B, but only QGpc.usw-B3 on 2B and QGpc.usw-A3 on 7A were expressed consistently in four and six environments, respectively. Positive alleles for GPC at these loci were contributed by the high-GPC parent Strongfield. The QGpc.usw-A3 QTL was validated in a second DH population, and depending on environment, selection for the Strongfield allele at barc108 resulted in +0.4% to +1.0% increase in GPC, with little effect on yield in most environments. Given the consistent expression pattern in multiple populations and environments, barc108 could be useful for marker-assisted selection for high GPC.

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Kluyveromyces marxianus possesses a useful potential to assimilate a wide variety of substrates at a high temperature, but the negative effect by coexisting glucose is critical for utilization of biomass containing various sugars. Such a negative effect on the activity of inulinase, which is the sole enzyme to hydrolyze sucrose, raffinose and inulin, has been demonstrated in K. marxianus without analysis at the gene level. To clarify the utilization capability of sucrose, raffinose and inulin and the glucose effect on inulinase in K. marxianus DMKU 3-1042, its growth and metabolite profiles on these sugars were examined with or without glucose under a static condition, in which glucose repression evidently occurs. Consumption of sucrose was not influenced by glucose or 2-deoxyglucose. On the other hand, raffinose and inulin consumption was hampered by glucose at 30°C but hardly hampered at 45°C. Unlike Saccharomyces cerevisiae, increase in glucose concentration had no effect on sucrose utilization. These sugar-specific glucose effects were consistent with the level of inulinase activity but not with that of the KmINU1 transcript, which was repressed in the presence of glucose via KmMig1p. This inconsistency may be due to sufficient activity of inulinase even when glucose is present. Our results encourage us to apply K. marxianus DMKU 3-1042 to high-temperature ethanol fermentation with biomass containing these sugars with glucose.

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Currently, studies on English for Tourism course mainly focuses on need analysis and material development. A few studies highlight the teaching methods for successful learning of the course. This study discusses the implementation of virtual exhibition simulation as a project based learning in the course of English for Tourism enrolled by students of tertiary education majoring English Literature. It aims at revealing the learning process as well as revealing the opportunities and challenges of the activity. Five lecturers are selected as the subject of the study. The data collected through semi structured interview and further qualitatively analysed by seeing the common and unique features. The findings suggest that the implementation of virtual exhibition project should be followed by lecturers’ teaching strategies in the step of preparation, rehearsal and exhibition in order to achieve learning objectives. Despite the technical challenge on internet connection and students’ reluctance that lecturers should cope with, this activity is seen as an alternative method that reflect contextual learning and give students English learning opportunity through intensive interaction and creativity.

2011. Nitrogen remobilization and post-anthesis nitrogen uptake in relation to elevated grain protein concentration in durum wheat. Can. J. Plant Sci. 91: 273Á282. Grain protein concentration is an important end-use suitability factor in durum wheat [Triticum turgidum L. ssp. durum (Desf.)Husn.] through its effect on cooking quality. Genetic differences in grain protein concentration are exploited in Canadian durum breeding programs, but the physiological basis of these differences remains unknown. Eighteen durum genotypes varying in grain protein concentration were grown at three pre-selected Saskatchewan locations that differ for soil nitrogen (N). These included check cultivars and six low-and six high-protein doubled haploid (DH) selections from the cross DT695)Strongfield (low-by high-protein). Plants were sampled at the anthesis, milk, dough and physiological maturity developmental stages, and dry matter and N concentration of plant parts were determined. The high-protein selections expressed 0.6 to 1.1 percentage units higher grain protein concentration than the low selections over the three environments (PB0.05), but yielded less grain than the low selections in two of the three environments. Remobilization of N from vegetative organs to grain varied with environment and accounted for 73 to 98% of grain N, the remainder made up from post-anthesis N uptake. The high-protein selections showed greater post-anthesis N uptake than the low selections in two of three environments (P B0.01), but lower N remobilization from vegetative organs to the grain than the low selections in the same environments (PB0.05). Subtle differences in N and dry matter partitioning accounted for the observed differences in grain protein concentration. Suprayogi, Y., Clarke, J. M., Bueckert, R., Clarke, F. R. et Pozniak, C. J. 2011. La remobilisation de l'azote et l'absorption d'azote apre`s l'anthe`se, et leurs liens avec la concentration e´leve´e de prote´ines dans le grain du ble´dur. Can. J. Plant Sci. 91: 273Á282. La concentration de prote´ines dans le grain joue un roˆle important dans l'utilite´du ble´dur (Triticum turgidum L.ssp. durum (Desf.) Husn.), ce facteur affectant la qualite´a`la cuisson. Les programmes d'hybridation canadiens exploitent la variation ge´ne´tique de la concentration de prote´ines dans le grain, mais on ignore l'origine physiologique des e´carts observe´s. Les auteurs ont cultive´dix-huit ge´notypes de ble´dur a`concentration de prote´ines variable dans le grain. Les essais se sont de´roule´s a`trois endroits de la Saskatchewan, pre´se´lectionne´s en raison d'une teneur en azote (N) variable dans le sol. Les ge´notypes incluaient des cultivars te´moins et six doubles haploı¨des a`faible ou a`forte teneur en prote´ines issus du croisement DT695)Strongfield (varie´te´a`faible teneur en prote´ines avec varie´te´a`forte teneur en prote´ines). Les plants ont e´te´e´chantillonne´s a`l'anthe`se, au stade du grain laiteux, au stade paˆteux et a`la maturite´physiologique, et les auteurs ont de´termine´la quantit...