Biomass Depolymerization projects

Ecology and Exploitation of Endophytic Diazotrophic Bacteria in Biofuel Crops - Completed

This project investigated the contribution of nitrogen-fixing endophytes to bioenergy crops and designed strategies to promote colonization of N2-fixing endophytes through selection of favorable host/environment combinations, and through development of endophyte populations with traits that enhance sustainability of biofuel crops.

 

project Highlights

2011 Highlights

Kent’s group used multiple lines of experimental evidence to demonstrate nitrogen fixation in field-grown Miscanthus x giganteus and identified the microbes responsible. Moreover, 15N isotope studies demonstrated that 16% of the nitrogen acquired by the plants was via biological nitrogen fixation. Quantitative PCR confirmed the presence of nitrogenase genes in endophytic bacteria, and Kent’s team demonstrated that Miscanthus harbors a greater proportion of endophytes capable of N fixation than switchgrass.  Researchers also demonstrated that Miscanthus-associated diazotrophs exhibit biogeographical patterns in both native and cultivated Miscanthus: native Miscanthus has more diverse endophyte populations than Mxg planted in Illinois. Additional data analysis has suggested a number of soil factors responsible for shaping Miscanthus-associated diazotrophs.

2010 Highlights

Researchers demonstrated that N fixation occurs in Miscanthus under field conditions using acetylene reduction assays and isotope dilution approaches. They cultured active gamma-proteobacteria diazotrophs, and detected a diverse assemblage of diazotrophs using culture-independent approaches. Differences in diazotroph abundance and community composition are correlated with differences in crop type, plant age, and soil chemistry. Low abundance of diazotrophs is detected in soils with higher total N.

2009 Highlights

Stable isotope addition experiments are being used to further explore the link between nitrogen-fixing bacteria and plant nitrogen sources. The factors shaping the communities of rhizome-associated bacteria for stands of native established Miscanthus species were investigated for sampling sites across Taiwan. Cultivation-independent molecular methods revealed a number of factors that correlate well with composition of the bacterial community. Differences between endophyte and rhizosphere communities were especially important, while other contributing factors included plant species, plant age, soil moisture, organic matter, and calcium concentration.

 


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