Insights into corn genes derived from large-scale cDNA sequencing

We present a large portion of the transcriptome of Zea mays, including ESTs representing 484,032 cDNA clones from 53 libraries and 36,565 fully sequenced cDNA clones, out of which 31,552 clones are non-redundant. These and other previously sequenced transcripts have been aligned with available genome sequences and have provided new insights into the characteristics of gene structures and promoters within this major crop species. We found that although the average number of introns per gene is about the same in corn and Arabidopsis, corn genes have more alternatively spliced isoforms. Examination of the nucleotide composition of coding regions reveals that corn genes, as well as genes of other Poaceae (Grass family), can be divided into two classes according to the GC content at the third position in the amino acid encoding codons. Many of the transcripts that have lower GC content at the third position have dicot homologs but the high GC content transcripts tend to be more specific to the grasses. The high GC content class is also enriched with intronless genes. Together this suggests that an identifiable class of genes in plants is associated with the Poaceae divergence. Furthermore, because many of these genes appear to be derived from ancestral genes that do not contain introns, this evolutionary divergence may be the result of horizontal gene transfer from species not only with different codon usage but possibly that did not have introns, perhaps outside of the plant kingdom. By comparing the cDNAs described herein with the non-redundant set of corn mRNAs in GenBank, we estimate that there are about 50,000 different protein coding genes in Zea. All of the sequence data from this study have been submitted to DDBJ/GenBank/EMBL under accession numbers EU940701–EU977132 (FLI cDNA) and FK944382-FL482108 (EST)

Use of Treated Effluent Water in Cellulosic Ethanol Production

The bioethanol industry exerts a significant demand on water supplies. Current water consumption rate in corn dry grind ethanol plants is 3 to 4 gallons of water per gallon of ethanol produced (gal/gal) and 6 to 10 gal/gal for cellulosic ethanol plants. The main goal of this study was to examine the use of treated wastewater effluent in place of potable freshwater for cellulosic ethanol production. The effects of using two different types of filtered treated effluent; Bloomington- Normal, IL (Residential type) and Decatur, IL (Industrial/Residential Mix type); on the rate of fermentation and final ethanol yield from a pure cellulosic substrate were evaluated. Final ethanol concentration with Bloomington- Normal and Decatur effluent and our control study using de-ionized water were similar, resulting in 4.57 0.22 % v/v (0.36 g/g, db), 4.74 0.13 % v/v (0.37 g/g, db) and 4.55 0.28 % v/v (0.36 g/g, db), respectively. Residual glucose concentrations were <0.04 % w/v at 48 hr in all cases, suggesting complete fermentation. Further study with Decatur effluent using 0.08 mm finely ground Miscanthus as the substrate resulted in a final ethanol concentration of 0.46 0.008 % v/v (0.14 g/g db) which was similar to ethanol concentration of 0.52 0.07 % v/v (0.17 g/g db) obtained with control treatment using de-ionized water. These findings suggest that with proper characterization studies and under appropriate conditions, the use of treated effluent water in cellulosic ethanol production is feasible.published or submitted for publicatio