Catalina Arango Pinedo, Ph.D.

Associate Professor
Office: Science Center 126
Research Lab: Science Center 106
Phone: 610-660-1895
Fax: 610-660-1832

Most of the research in my laboratory is on Sinorhizobium meliloti.  S. meliloti, a bacterium that is beneficial for agriculture, can live in the soil as a free living organism, or in symbiosis with legumes such as alfalfa, which makes it an interesting research model. As a plant symbiont, S. meliloti infects alfalfa plants by entering the plant through the root hairs and colonizing a plant-derived structure called the nodule. Once in the nodule, bacteria fix nitrogen from the air for the plant in exchange for carbon necessary for survival.

Currently I am interested in two aspects of S. meliloti: gene regulation as it relates to catabolite repression and biofilm formation. Catabolite repression is one of the most important systems of global regulation in bacteria. The most evident role of catabolite repression is to prioritize the use of carbon sources when they are available to the cells simultaneously. Interestingly, the mechanisms of catabolite repression also greatly influence other cellular processes. Catabolite repression affects carbon and nitrogen utilization, symbiosis, chemotaxis, virulence, and biofilm formation.

Biofilm formation is an important trait for S. meliloti as a plant symbiont because it may aid in attachment to roots and root hairs that can result in root hair infection. Not a lot is known about biofilm formation in S. meliloti. A handful of genes that are involved in biofilm formation have been identified, genes that are also main players in the symbiotic process. Future research in the Arango lab will be directed towards finding other genes that are important for formation of biofilms, and eventually elucidate the relationship between catabolite repression, biofilm formation and symbiosis in S. meliloti.


  • B.A. (1992) Civil Engineering, Universidad de los Andes
, Bogota, Colombia
  • M.S. (1994) Civil and Environmental Engineering, Universidad de los Andes
, Bogota, Colombia
  • Ph.D. (2000) in Environmental Engineering University of Massachusetts, Amherst

Professional Experience

Post-Doctoral Research Fellow, (2001-2003), Department of Civil and Environmental Engineering; (2003-2009), Department of Molecular and Cell Biology, University of Connecticut

Adjunct Faculty (2000), University of Hartford, Hartford, CT

Adjunct Faculty (1997-Summer), Universidad de los Andes, Bogota, Colombia

Assistant Professor (2010-2016), Department of Biology, Saint Joseph‘s University, Philadelphia, PA

Associate Professor (2016-present), Department of Biology, Saint Joseph's University, Philadelphia, PA

Courses Taught

  • Biology II: Genetic and Evolutionary Biology
  • Microbiology


Morrow, J.B., Arango Pinedo, C.  and R.D. Holbrook, 2010. Association of quantum dot nanoparticles with Pseudomonas aeruginosa biofilm. Journal of environmental Quality. Accepted for publication.

Arango Pinedo, C. and D.J.Gage, 2009. The rha-insertion plasmids, a versatile tool for genetic studies in Sinorhizobium meliloti. Journal of Molecular Microbiology and Biotechnology 2009;17:201–210.

Arango Pinedo, C. and D.J.Gage, 2009. HPrK regulates succinate-mediated catabolite repression in the Gram negative symbiont Sinorhizobium meliloti . Journal of Bacteriology. 191:298-309.

Gage, D.J., Herron, P.M., Arango Pinedo, C., and Zoe G. Cardon, 2008. Live reports from the soil grain  -- the promise and challenge of microbiosensors. Functional Ecology, 22:983-989.

Arango Pinedo, C., Bringhurst, R.B. and D.J.Gage, 2008.Sinorhizobium meliloti mutants lacking PTS enzymes HPr or EIIA are altered in diverse processes including carbon metabolism, cobalt requirements and succinoglycan production. Journal of Bacteriology. 190: 2947-2956.

Monahan-Giovanelli H., Arango Pinedo , C., and D. J. Gage, 2006. Architecture of Infection Thread Networks in Developing Root Nodules Induced by the Symbiotic Bacterium Sinorhizobium meliloti on Medicago truncatula, Plant Physiology, 140: 661-670

Arango Pinedo, C. and B.F. Smets, 2005. Conjugal TOL Transfer from  Pseudomonas putida to Pseudomonas aeruginosa: Effects of Restriction Proficiency, Toxicant Exposure, Cell Density Ratios and Conjugation Detection Method on Observed Transfer Efficiencies, Applied and Environmental Microbiology, 71: 51-57.

Long, S., Arango P., C., and J.D. Plummer. 2005. An Optimized EnumerationMethod for Sorbitol-Fermenting Bifidobacteria in Environmental Samples. Canadian Journal of Microbiology, 51: 413-422.

Smets, B.F., Morrow, J.B.  and C. Arango Pinedo. 2003. Plasmid introduction in metal-stressed, subsurface-derived microcosms: plasmid fate and community response. Applied and Environmental Microbiology, 69: 4087-4097.

Long, S.C., Shafer, E.J., Arango P., C. and D. Siraco. 2003.  Evaluation of Three Source-Specific Indicator Organisms