Ai Yamaguchi


July 2010

Document Type


Degree Name



Dept. of Science & Engineering


Oregon Health & Science University


Manganese is the second most abundant transition metal element in the Earth’s crust. Many different bacteria produce enzymes that catalyze Mn(II)-oxidation, but the biochemical pathway of this process is still not fully understood. Therefore, to identify genes responsible for Mn(II) oxidation, random transposon mutagenesis was performed on one of the known Mn(II)-oxidizing bacteria, Pseudomonas putida GB-1. Several mutants exhibiting decreased Mn(II)-oxidation were identified and the gene(s) disrupted in these mutants was identified by sequencing out from the site of transposon insertion. Unexpectedly, however, there were some mutants that started oxidizing Mn(II) earlier than the wild-type, and all those mutants had the transposon insertion in motility-related genes. When the motility on low agar concentration plates was tested, some of them were completely non-motile, and the rest were very slow swimmers. Complementation with plasmid-borne copies of the motility genes further confirmed a relationship between motility and Mn(II) oxidation. This is the first time that a relationship between Mn(II) oxidation and motility of the bacterium and/or flagella synthesis has been observed. In addition, those mutants that had faster oxidation rate now had a slower than wild-type oxidation rate on the motility agar. Further investigation of the effect of growth conditions on Mn(II) oxidation by different mutant strains revealed a requirement for different genes depending on the growth condition, such as growth substrate and temperature. These results demonstrate the complexity of the regulation of Mn(II) oxidation in P. putida GB-1.




Div. of Environmental & Biomolecular Systems


School of Medicine



To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.