GC: n
CT: Biotechnological approaches to reduce or modify lignin in biomass crops are predicated on the assumption that it is the principal determinant of the recalcitrance of biomass to enzymatic digestion for biofuels production. We defined quantitative trait loci (QTL) in the Intermated B73 x Mo17 (IBM) recombinant inbred maize (Zea mays) population using pyrolysis molecular-beam mass spectrometry to establish stem lignin content and an enzymatic hydrolysis assay to measure glucose and xylose yield. Among five multi-year QTL for lignin abundance, two for 4-vinylphenol abundance, and four for glucose and/or xylose yield, not a single QTL for aromatic abundance and sugar yield was shared. A genome-wide association study (GWAS) for lignin abundance and sugar yield of the 282-member maize Association Panel provided candidate genes in the eleven QTL of the B73 and Mo17 parents, but showed that many other alleles impacting these traits exist among this broader pool of maize genetic diversity. B73 and Mo17 genotypes exhibited large differences in gene expression in developing stem tissues independent of allelic variation. Combining these complementary genetic approaches provides a narrowed list of candidate genes. A cluster of Scarecrow-like9 and Scarecrow-like14 transcription factor genes provides exceptionally strong candidate genes emerging from the GWAS study. In addition to these and genes associated with cell-wall metabolism, candidates include several other transcription factors associated with vascularization and fiber formation, and components of cellular signaling pathways. These results provide new insights and strategies beyond modification of lignin to enhance yields of biofuels from genetically modified biomass.
S: http://www.researchgate.net/publication/263477919_Genetic_determinants_for_enzymatic_digestion_of_lignocellulosic_biomass_are_independent_of_those_for_lignin_abundance_in_a_maize_recombinant_inbred_population (last access: 27 December 2014)
N: 1. enzymatic (adj): From enzyme (1881, as a biochemical term, from German Enzym, coined 1878 by German physiologist Wilhelm Kühne (1837-1900), from Modern Greek enzymos “leavened,” from en “in” + zyme “leaven”. Related: Enzymotic).
Of, relating to, or produced by an enzyme. Also enzymic.
First Known Use of enzymatic: 1900.
digestion (n): late 14c., from Old French digestion (13c.), from Latin digestionem (nominative digestio), noun of action from past participle stem of digerere.
2. Enzymatic hydrolysis of a large number of not-treated and pretreated biomass samples of various origins containing different amounts of cellulose, hemicelluloses and lignin has been studied. To disclose the effect of individual polymeric components on yield of glucose, a correlation analysis was performed and squared correlation coefficients (R2) were calculated. This analysis showed that hemicelluloses have a negligible impact on enzymatic digestion of the cellulosic component. Content of lignin affected negatively on enzymatic cleavage of cellulose, and namely an inversely proportional regression between content of lignin in the samples and yield of glucose was observed (R2 = 0.68). Conversely, increased cellulose content in the biomass affects positively on enzymatic digestion and glucose output (R2 = 0.90). The best correlation (R2 = 0.98) was found for the dependence of glucose yield (Y) on difference between contents of cellulose and lignin (X) in the investigated biomass samples. Thus, increasing the content of cellulose and decreasing the content of lignin in the samples promotes enzymatic cleavage of the cellulosic component. The discovered correlation Y=F(X) is a basis of choice the best pretreatment method. In particular, the mild alkaline pretreatment supplemented with bleaching can be a quite efficient method since it provides obtaining the delignified biomass enriched with cellulose that shows an excellent enzymatic digestibility.
S: 1. MW – http://www.merriam-webster.com/dictionary/enzymatic (last access: 27 December 2014); OED – http://www.etymonline.com/index.php?allowed_in_frame=0&search=enzyme&searchmode=none; http://www.etymonline.com/index.php?allowed_in_frame=0&search=digestion&searchmode=none (last access: 27 December 2014). 2. http://www.academia.edu/9097146/Correlation_Analysis_of_Enzymatic_Digestibility_of_Plant_Biomass (last access: 27 December 2014).
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CR: bioethanol , biomass, biomass energy.
