Great Lakes Bioenergy research consistently results in new discoveries and new technologies. Here, we highlight high-impact research from all three of our research areas.
OPTSSEQ: High-throughput sequencing readout of growth enrichment defines optimal gene expression elements
OptSSeq (Optimization by Selection and Sequencing) is a newly developed approach to identifying optimally balanced enzyme levels in synthetic biofuel production pathways. This method couples selection of enzyme expression levels with high-throughput gene sequencing to track enrichment of gene expression elements from a combinatorial library.
To explore the genetic architecture of flowering time, we developed a recombinant inbred line population from a cross between two diverse accessions of the grass Brachypodium distachyon that have different flowering behavior. We then used a genotyping-by-sequencing approach to identify six quantitative trait locis that control differences in flowering time.
Many genomic positions in switchgrass contribute to flowering time, a major biomass yield determinant
We performed genome-wide association studies to characterize the genetic architecture and genes underlying flowering time regulation in switchgrass. We then identified association with flowering time at multiple loci, including in a homolog of the gene FLOWERING LOCUS T and in a locus containing the gene TIMELESS, a homolog of a key circadian regulator in animals.
Developmental regulation of processes, pathways, and genes that affect stem growth and composition in sorghum
We collected sorghum stem RNA-seq transcriptome profiles and composition data for approximately 100 days of development beginning at floral initiation. Our analysis identified more than 200 differentially expressed genes involved in stem growth, cell wall biology, and sucrose accumulation.
The production of fuels from lignocellulosic biomass can play an important role in reducing our dependence on fossil fuels while meeting an increasing energy demand. In an effort to meet these goals, regional biomass processing depots have been introduced as a way to improve the biomass supply network.
The effects of variable precipitation on downstream processing and fermentation of biomass to biofuels have not been well studied. This study demonstrates that increased plant soluble sugars produced during drought stress are made into pyrazines and imidazoles during ammonia-based pretreatment and are inhibitory to microbial growth.
We report that using formaldehyde to stabilize lignin during extraction leads to near-theoretical yields of lignin monomers after hydrogenolysis of the extracted product. These yields were three to seven times higher than those obtained when using the analogous method without formaldehyde.
Yeast evolved for enhanced xylose utilization reveal interactions between cell-signaling pathways and iron-sulfur cluster biogenesis
A stress-tolerant yeast strain was evolved for enhanced xylose utilization under aerobic or anaerobic growth conditions, the causative mutations identified by whole-genome sequencing, and systems-level effects of the mutations on cellular metabolism were analyzed. Rapid xylose utilization was found to be dependent upon genetic interactions among four genes, uncovering a surprising connection between Fe-S cluster assembly and cell signaling that facilitates aerobic respiration and anaerobic fermentation of xylose.
Plants have convergently evolved to use "zips" (chemically labile ester linkages) in their lignin polymers
With a sensitive analytical method for diagnostically detecting incorporation of chemically labile ester bonds introduced into lignin polymers by augmenting the prototypical monomers with monolignol ferulate conjugates (“zip monomers”), we reexamined the lignin of three plants known to produce such conjugates in their extractives and found that these plants also used monolignol ferulate conjugates in their lignification. This discovery prompted a survey of a set of plants representing spermatophytes or “seed plants,” including 13 gymnosperms and 54 angiosperms.
The electrochemical oxidation of alcohols is a major focus of energy and chemical conversion efforts, with potential applications ranging from fuel cells to biomass utilization and chemical synthesis.