Saathoff A.J.,Forage and Bioenergy Research Unit |
Sarath G.,Forage and Bioenergy Research Unit |
Chow E.K.,Genomics and Gene Discovery Research Unit |
Dien B.S.,Bioenergy Research Unit |
Tobias C.M.,Genomics and Gene Discovery Research Unit
PLoS ONE | Year: 2011
Cinnamyl alcohol dehydrogenase (CAD) catalyzes the last step in monolignol biosynthesis and genetic evidence indicates CAD deficiency in grasses both decreases overall lignin, alters lignin structure and increases enzymatic recovery of sugars. To ascertain the effect of CAD downregulation in switchgrass, RNA mediated silencing of CAD was induced through Agrobacterium mediated transformation of cv. "Alamo" with an inverted repeat construct containing a fragment derived from the coding sequence of PviCAD2. The resulting primary transformants accumulated less CAD RNA transcript and protein than control transformants and were demonstrated to be stably transformed with between 1 and 5 copies of the TDNA. CAD activity against coniferaldehyde, and sinapaldehyde in stems of silenced lines was significantly reduced as was overall lignin and cutin. Glucose release from ground samples pretreated with ammonium hydroxide and digested with cellulases was greater than in control transformants. When stained with the lignin and cutin specific stain phloroglucinol-HCl the staining intensity of one line indicated greater incorporation of hydroxycinnamyl aldehydes in the lignin.
Chen M.-H.,University of Illinois at Urbana - Champaign |
Kaur P.,University of Illinois at Urbana - Champaign |
Dien B.,Bioenergy Research Unit |
Below F.,University of Illinois at Urbana - Champaign |
And 2 more authors.
World Journal of Microbiology and Biotechnology | Year: 2013
Tropical maize is an alternative energy crop being considered as a feedstock for bioethanol production in the North Central and Midwest United States. Tropical maize is advantageous because it produces large amounts of soluble sugars in its stalks, creates a large amount of biomass, and requires lower inputs (e.g. nitrogen) than grain corn. Soluble sugars, including sucrose, glucose and fructose were extracted by pressing the stalks at dough stage (R4). The initial extracted syrup fermented faster than the control culture grown on a yeast extract/phosphate/sucrose medium. The syrup was subsequently concentrated 1.25-2.25 times, supplemented with urea, and fermented using Saccharomyces cerevisiae for up to 96 h. The final ethanol concentrations obtained were 8.1 % (v/v) to 15.6 % (v/v), equivalent to 90.3-92.2 % of the theoretical yields. However, fermentation productivity decreased with sugar concentration, suggesting that the yeast might be osmotically stressed at the increased sugar concentrations. These results provide in-depth information for utilizing tropical maize syrup for bioethanol production that will help in tropical maize breeding and development for use as another feedstock for the biofuel industry. © 2013 Springer Science+Business Media Dordrecht.
Zhang X.,Beifang University of Nationalities |
Nghiem N.P.,U.S. Department of Agriculture |
Hicks K.B.,U.S. Department of Agriculture |
Johnston D.B.,U.S. Department of Agriculture |
Hector R.E.,Bioenergy Research Unit
Industrial Biotechnology | Year: 2014
Barley straw and hull were both subjected to alkaline hydrogen peroxide treatment for extraction of the hemicellulose fractions. The cellulose-enriched residues were then used as substrates for ethanol production in a high-solids fed-batch simultaneous saccharification and fermentation (SSF) process using commercial Sacharomyces cerevisiae and YRH400, a S. cerevisiae strain genetically engineered for xylose metabolism. The total process time was 8 days, with the first day dedicated solely to enzymatic hydrolysis and the remaining time for the SSF. Higher ethanol production was obtained with YRH400 with both residues. The final ethanol concentrations produced from the cellulose-enriched residue of barley straw by the commercial yeast and YRH400 were 63.8 g/L and 73.1 g/L, respectively, while the corresponding ethanol yields were 0.10 g/g and 0.12 g/g. The tendency of the cellulose-enriched residue of barley hull to absorb more water caused the formation of a highly viscous slurry that prevented good mixing and restricted mass transfer, which resulted in lower ethanol production. The final ethanol concentrations produced from this residue by the commercial yeast and YRH400 were 40.2 g/L and 43.6 g/L, respectively, while the corresponding ethanol yields were 0.06 g/g and 0.07 g/g. © 2014, Mary Ann Liebert, Inc.
Genome analysis shows Bacillus axarquiensis is not a later heterotypic synonym of Bacillus mojavensis; reclassification of Bacillus malacitensis and Brevibacterium halotolerans as heterotypic synonyms of Bacillus axarquiensis
Dunlap C.A.,Crop Bioprotection Unit |
Bowman M.J.,Bioenergy Research Unit |
Schisler D.A.,Crop Bioprotection Unit |
Rooney A.P.,Crop Bioprotection Unit
International Journal of Systematic and Evolutionary Microbiology | Year: 2016
Bacillus axarquiensis and Bacillus malacitensis were previously reported to be later heterotypic synonyms of Bacillus mojavensis, based primarily on DNA–DNA relatedness values. We have sequenced draft genomes of Bacillus axarquiensis NRRL B-41617T and Bacillus malacitensis NRRL B-41618T. Comparative genomics and DNA–DNA relatedness calculations showed that while Bacillus axarquiensis and Bacillus malacitensis are synonymous with each other, they are not synonymous with Bacillus mojavensis. In addition, a draft genome was completed for Brevibacterium halotolerans, a strain long suspected of being a Bacillus subtilis group member based on 16S rRNA similarities (99.8 % with Bacillus mojavensis). Comparative genomics and DNA–DNA relatedness calculations showed that Brevibacterium halotolerans is synonymous with Bacillus axarquiensis and Bacillus malacitensis. The pairwise in silico DNA–DNA hybridization values calculated in comparisons between the three conspecific strains were all greater than 92 %, which is well above the standard species threshold of 70 %. While the pairwise in silico DNA–DNA hybridization values calculated in comparisons of the three conspecific strains with Bacillus mojavensis were all less than 65 %. The combined results of our genotype and phenotype studies showed that Bacillus axarquiensis, Bacillus malacitensis and Brevibacterium halotolerans are conspecific and distinct from Bacillus mojavensis. Because the valid publication of the name Bacillus axarquiensis predates the publication of the name Bacillus malacitensis, we propose that Bacillus malacitensis be reclassified as a synonym of Bacillus axarquiensis. In addition, we propose to reclassify Brevibacterium halotolerans as a synonym of Bacillus axarquiensis. An amended description of Bacillus axarquiensis is provided. © 2016 IUMS.
Polyphenol oxidase, an enzyme found in all plants, causes undesirable reactions such as browning in sliced apples, black spots in cut avocados, and dark marks on banana peels. It's also responsible for gray discoloration in wheat products such as fresh noodles, fresh and frozen breads, and refrigerated biscuits—all made from hard white wheat. Hard white wheat products such as white whole-grain breads are becoming more popular in the U.S. marketplace. Hard white wheat is the wheat of choice in select export markets, especially in Asia, where it is used to make a variety of fresh noodle products. High levels of polyphenol oxidase in the grain make U.S. hard white wheats undesirable and place them at a disadvantage relative to wheats from Australia in the Asian markets, says Bob Graybosch, plant geneticist and research leader of the Agricultural Research Service's (ARS) Grain, Forage, and Bioenergy Research Unit in Lincoln, Nebraska. "Polyphenol oxidase is a big deal for Asian markets, because they don't want to see gray noodles when they hang them up to dry and then sell." For 15 years, Graybosch has been studying the polyphenol oxidase trait in wheat, investigating numerous samples of white wheat obtained from the ARS National Small Grains Collection (NSGC), in Aberdeen, Idaho. "A lot of U.S. white wheats still have high levels of polyphenol oxidase," Graybosch says. "To have a successful white wheat for both the export market and the domestic market, milling companies want low or no polyphenol oxidase." Some low-polyphenol oxidase hard winter white wheats have been developed, but complete removal of this enzyme trait is more desirable. In 2000, working with the University of Nebraska and Montana State University, Graybosch screened more than 3,000 wheats from the NSGC for the presence of polyphenol oxidase. The team then mated wheats that had low levels of the enzyme. Wheat breeding lines with very low or even near-zero levels of polyphenol oxidase were generated from these crosses. "And lo and behold, we did it," he says. "We developed a wheat with practically no polyphenol oxidase." Graybosch produced the wheat line, called "070R1074," by crossing two Australian wheats that were entered into the small-grains germplasm collection in the 1930s."For 70 years, these two Australian wheats have been in the germplasm collection with this trait of interest and economic importance that the milling industry and exporters need and want," Graybosch says. "This demonstrates the value of this diversified wheat collection. You don't always know what you have until you do something with it."