Characterization of Pinitol Catabolism in Sinorhizobium Meliloti and its Role in Nodule Occupancy
Date of Award
Master of Science
Dr. Silvia Rossbach
Todd Barkman, Ph.D.
Jian Yao, Ph.D.
Pinitol, d-chiro-inositol, nodules, sinorhizobium melitoti, nitrogen fixation
Masters Thesis-Open Access
Sinorhizobium meliloti, which is the nitrogen fixing symbiont of Medicago sativa (alfalfa), was used to test the hypothesis that D-chiro-inositol is an intermediate of pinitol catabolism and that pinitol catabolism plays a role in S. melilot s ability to compete for nodule occupancy. An analytical method, involving gas chromatography and mass spectrometry (GCMS), was developed to detect and separate pinitol and D-chiro-inositol. The S. meliloti wild type, and three isogenic mutant strains (idhA, mocD, and mocE) were grown in minimal medium with pinitol and pinitol plus glycerol. The S. meliloti wild type can utilize pinitol as a sole carbon source, whereas the mutant strains cannot. The idhA mutant removed 50% of the detectable pinitol from the medium when grown with pinitol plus glycerol and showed accumulation of Dchiro- inositol. Therefore, it was concluded that D-chiro-inositol is indeed an intermediate of pinitol catabolism. To test the ability of pinitol catabolism mutants to compete with the wild type for nodule occupancy, alfalfa plants were inoculated with a 1:1 ratio of wild type S. meliloti and the idhA, mocD, and mocE mutants. Plants nodules were collected at eight and 16 weeks and the percentage of the nodule inhabitants was determined. Each mutant was found to be outcompeted by the wild type by week 16. Therefore, it was concluded that the ability to catabolize pinitol does indeed play a role in nodule occupancy.
Kennedy-Mendez, Angela Irene, "Characterization of Pinitol Catabolism in Sinorhizobium Meliloti and its Role in Nodule Occupancy" (2018). Masters Theses. 3417.