Impacts of kafirin allelic diversity, starch content, and protein digestibility on ethanol conversion efficiency in grain sorghum

Cremer, Julie E., Liu, Liman, Bean, Scott R., Ohm, Jae-Bom, Tilley, Michael, Wilson, Jeff D., Kaufman, Rhett C., Vu, Thanh H., Gilding, Edward K., Godwin, Ian D. and Wang, Donghai (2014) Impacts of kafirin allelic diversity, starch content, and protein digestibility on ethanol conversion efficiency in grain sorghum. Cereal Chemistry, 91 3: 218-227. doi:10.1094/CCHEM-04-13-0068-R


Author Cremer, Julie E.
Liu, Liman
Bean, Scott R.
Ohm, Jae-Bom
Tilley, Michael
Wilson, Jeff D.
Kaufman, Rhett C.
Vu, Thanh H.
Gilding, Edward K.
Godwin, Ian D.
Wang, Donghai
Title Impacts of kafirin allelic diversity, starch content, and protein digestibility on ethanol conversion efficiency in grain sorghum
Journal name Cereal Chemistry   Check publisher's open access policy
ISSN 0009-0352
1943-3638
Publication date 2014-01-01
Year available 2014
Sub-type Critical review of research, literature review, critical commentary
DOI 10.1094/CCHEM-04-13-0068-R
Volume 91
Issue 3
Start page 218
End page 227
Total pages 10
Place of publication Paul, MN United States
Publisher American Association of Cereal Chemists
Language eng
Subject 1106 Human Movement and Sports Science
1605 Policy and Administration
Abstract Seed protein and starch composition determine the efficiency of the fermentation process in the production of grain-based ethanol. Sorghum, a highly water- and nutrient-efficient plant, provides an alternative to fuel crops with greater irrigation and fertilizer requirements, such as maize. However, sorghum grain is generally less digestible because of extensive disulfide cross-linking among sulfur-rich storage proteins in the protein- starch matrix. Thus, the fine structure and composition of the seed endosperm directly impact grain end use, including fermentation performance. To test the hypothesis that kafirin (prolamin) seed storage proteins specifically influence the efficiency of ethanol production from sorghum, 10 diverse genetic lines with allelic variation in the β-, γ-, and δ-kafirins, including three β-kafirin null mutants, were tested for ethanol yield and fermentation efficiency. Our selected lines showed wide variation in grain biochemical features, including total protein (9.96-16.47%), starch (65.52-74.29%), and free amino nitrogen (FAN) (32.84-73.51 mg/L). Total ethanol yield (ranging from 384 to 426 L/metric ton), was positively correlated to starch content (R2 = 0.74), and there was a slight positive correlation between protein digestibility and ethanol yield (R2 = 0.52). Increases in FAN content enhanced fermentation efficiency (R2 = 0.65). The highest ethanol producer was elite staygreen breeding line B923296, and the line with the highest fermentation efficiency at the 72 h time point was inbred BT×623. A large-seeded genotype, KS115, carrying a novel γ-kafirin allele, was rich in FAN and exhibited excellent short-term fermentation efficiency at 85.68% at the 20 h time point. However, the overall ethanol yield from this line was comparatively low at 384 L/metric ton, because of insufficient starch, low digestibility, and high crude protein. Multivariate analysis indicated an association between the β-kafirin allele and variation in grain digestibility (P = 0.042) and FAN (P = 0.036), with subsequent effects on ethanol yield. Reversed-phase HPLC profiling of the alcohol-soluble kafirin protein fraction revealed diversity in protein content and composition across the lines, with similarities in peak distribution profiles among β-kafirin null mutants compared with normal lines.
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Critical review of research, literature review, critical commentary
Collections: School of Agriculture and Food Sciences
Official 2015 Collection
Institute for Molecular Bioscience - Publications
 
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