Jonathan J. Caguiat
Associate Professor
Molecular Biology and Microbiology Division

Assistant Professor
Youngstown State University
Youngstown, OH 44555-3601
Phone: (330) 941-2063
E-mail: jjcaguiat@ysu.edu
Web Site: 

  
Education
Courses I Teach
Research
 
Survey of metal resistant bacteria from a mercury contaminated site

The Y-12 plant in Oakridge, TN processed uranium during World War II to make the first atomic bomb and lithium during the Cold War to make hydrogen bombs. These processes contaminated the nearby stream, East Fork Poplar Creek, with mercury and other heavy metals. Stenotrophomas maltophilia Oakridge strain O2 (S. maltophilia O2), which was isolated from East Fork Poplar Creek, grew in the presence of toxic levels of zinc, copper, platinum, mercury, gold, cadmium, lead, silver, chromium and selenium. Nine hundred aerobic bacterial colonies were isolated from a site contaminated with 96 ppm mercury, and one thousand six hundred other colonies were isolated from a downstream site contaminated with 2 ppm mercury. We will screen each colony for growth in the presence of toxic concentrations of mercury, copper, zinc, lead, cadmium, chromium and selenium. The genes, which encode metal resistances in S. maltophilia O2, will then be identified using the polymerase chain reaction (PCR), and used to identify similar genes in the other isolates by colony hybridizations. The identity of the isolates will also be determined by sequencing their 16s ribosomal RNA.

Selenium Homeostasis in S. maltophiliaO2

Selenium (Se) is an important element in the diet of all living organisms, but too much can be toxic. In the presence of high concentrations of selenite (SeO32-), a toxic form of selenium, S. maltophilia O2 precipitates it from its culture medium by reducing it to elemental selenium (Se0). Thus, under high selenium concentrations, bacterium must maintain a balance or homeostasis of the amount of selenite that is incorporated into the cell and the amount of selenite that is detoxified.

Proteomics will be used to identify potential proteins involved in selenite homeostasis. S. maltophilia O2 will be grown in the presences and absence of 40 mM selenite and protein samples at different points of growth will be separated by 2-dimensional gel electrophoresis. Comparing the intensity of protein spots on gels containing protein samples from bacteria grown in the presence of selenite with gels containing samples from bacteria grown in the absence of selenite may identify proteins that are involved in selenium homeostasis. These proteins will be excised from the gels, digested with trypsin and identified by mass spectrometry.

Publications

Song, L., J. Caguiat, Z. Li, J. Shokes, R. A. Scott, L. Olliff and A. O. Summers (2003). Engineered Single Chain, Antiparallel, Coiled Coil Mimics MerR Metal Binding Site. J. Bacteriol. 186:1861-1868.

<>Caguiat, J. J., A. L. Watson and A. O. Summers (1999). Cd(II)-Responsive and Constitutive Mutants Implicate a Novel Domain in MerR. J. Bacteriol. 181:3462-3471.

Jackson, J. H., R. George, H. O. Adeyemi, M. A. Winrow, P. A. Herring, J. J. Caguiat<>, C. F. Mulks, R. Srikanth, S. H. Harrison and R. E. Mickens (1998). Characterization of Base Coding Periodicities in Protein-Coding Genes. J. Biol. Sys. 6:49-70.<>

Frasch, W.D., J. Green, J. Caguiat and A. Meija (1989). ATP Hydrolysis Catalyzed by a β-Subunit Preparation Purified from CF1•CF0. J. Biol. Chem. 264:5064-5069.

Summers, A. O. and J. Caguiat (2004). Metal Binding Proteins, Recombinant Host Cells and Methods. Patent Number 6,750,042.