Date of Award


Degree Name

Master of Arts


Biological Sciences

First Advisor

Dr. Silvia Rossbach

Second Advisor

Dr. John Geiser

Third Advisor

Dr. Yan Lu


Inositol, transport, catabolism, isomers, sinorhizobium meliloti

Access Setting

Masters Thesis-Campus Only

Restricted to Campus until



The nitrogen fixing symbiont of alfalfa, Sinorhizobium meliloti, is able to use inositols as the sole carbon source. In this thesis, the role of two genetic loci in S. meliloti was investigated; the first is involved in the transport of inositols and the second genetic locus is essential for the catabolism of D-chiro-inositol stereoisomers. The S. meliloti ibpA gene had been earlier described as playing a role in inositol transport, but this study identified the SMb20072 gene product, called IbpB, as a second periplasmic binding protein involved in inositol transport. A single ibpB mutant and a double mutant ibpAibpB were constructed. The growth of the ibpB mutant was reduced as compared to the wild type when myo-inositol, D-chiro-inositol or pinitol were provided as sole carbon source, whereas the ibpAibpB double mutant did not grow at all. In addition, a mutant containing a kanamycin cassette in the ioll-like SMb20711 gene was constructed to characterize its phenotype. The SMb20711 mutant did not grow when D-chiro-inositol was provided as the sole carbon source. Also, the growth of the SMb20711 mutant was impaired when it was grown with myo-inositol or pinitol as the sole carbon source as compared to the wild type. These results suggest that the SMb20711 gene is essential for D-chiro-inositol catabolism and was called ioll.

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