Off-campus UNL users: To download campus access dissertations, please use the following link to log into our proxy server with your NU ID and password. When you are done browsing please remember to return to this page and log out.

Non-UNL users: Please talk to your librarian about requesting this dissertation through interlibrary loan.

Identification and Characterization of Human Gut Microbiome Active Traits in Cereal Grains

Nate Korth, University of Nebraska - Lincoln


The composition and function of the human gut microbiome are associated with many aspects of human health and disease and are shaped by diet. Staple grains, which comprise a significant percentage of calories consumed by humans, consist of few elite hybrid lines that have been artificially selected for crop yield and resilience traits. A quantitative genetics approach was employed to identify and characterize novel plant traits that impact human nutrition mediated by the gut microbiome in a diverse population of sorghum. This work demonstrates genetic diversity in sorghum can explain variation in bacteria from the microbiomes of eight human subjects tested in vitro. In a genome-wide analysis, we identified loci in sorghum associated with gut microbes of two human subjects. Genome-wide mapping of various biochemical and agronomic traits in sorghum revealed seed traits likely causal for the microbiome associations. An identified locus on chromosome four encompasses the tan1 gene known to regulate condensed tannin accumulation in sorghum, which has been shown to have a tremendous impact on gut microbes. In a separate project, we examined the effects of genetic variation in a bulk nutritional trait (seed protein composition) using near-isogenic lines of maize popcorn with wildtype or quality protein popcorn mutations which lead to seed protein composition with higher levels of essential amino acids: lysine and tryptophan. Detailed analyses of the differential effects of popcorn vs quality protein popcorn on the gut bacteria resulted in the enrichment of butyrate-producing bacteria coupled with an increase in butyrate production associated with human health which can be attributed to a microbial enzymatic pathway for the conversion of lysine and fructoselysine to butyrate. Cumulatively, this work demonstrates that plant seed composition, driven by genetics, within two distinct species of grain crops has significant effects on gut microbes, particularly on microbial taxa considered to be beneficial. Further targeted breeding approaches to improve these nutritional traits can enhance a plant’s ability to enrich beneficial bacteria and metabolites ultimately improving human health.

Subject Area

Food Science|Microbiology|Agronomy

Recommended Citation

Korth, Nate, "Identification and Characterization of Human Gut Microbiome Active Traits in Cereal Grains" (2022). ETD collection for University of Nebraska-Lincoln. AAI29999780.