Associate Professor

Molecular microbiology; lung microbiota response to antibiotics in cystic fibrosis, bacterial source tracking methodology.

Academic Degrees

•   Ph.D., Biology, University of Rochester (1985)

•   M.S., Biology, University of Rochester (1982)

•   B.S., Biology, Allegheny College (1979)

Professional Experience

•   1985 - 1986, Research Associate, Department of Microbiology, Biochemistry and Molecular Biology, University of Pittsburgh

•   1986 - 1989, Post-Graduate Researcher, Department of Plant Pathology, University of California - Davis

•   1989 - 1991, Post-Doctoral Researcher, Department of Biological Sciences, Purdue University

•   1991 - present, Faculty, Department of Biology, UNC Charlotte

Courses Taught

•   BIOL 4255/5255 Bacterial Genetics

•   BIOL 4162/5262 Environmental Biotechnology I

•   BIOL 4168/5168 Recombinant DNA Techniques

•   BIOL 6000 Introduction to Biotechnology

Summary of Research

There are currently two research projects in the laboratory.

Change in microbiota in CF patients in response to antibiotic treatment.

Cystic Fibrosis (CF) affects the epithelial cells of mucus membranes in the human body. In the lungs, a mutation in the CFTR gene results in the production of thick, sticky mucus that becomes difficult to move out of the airways. Bacteria that are normally not pathogenic in the lungs grow in this mucus and cause chronic infections. In CF patients, there are several bacteria that are resistant to most known antibiotics, making treatment difficult. Bacteria in CF patients are usually characterized in a clinic by cultivation techniques, but culturing only identifies a fraction of bacteria.

New developments in sequencing technology are revolutionizing the study of complex microbial communities. The goals of this project being done in collaboration with Dr. Anthony Fodor (Bioinformatics & Genomics Department, UNC Charlotte) are to determine how antibiotics affect the microbial population in the lung, provide a detailed mechanistic view of how antibiotic resistance develops in CF patients, and determine if changes in the microbiota can predict onset of an exacerbation. These goals serve as the foundation for development of personalized courses of treatment to manage infections. Two techniques currently being used are pyrosequencing and qPCR.

In preliminary experiments analyzing sputum samples from a CF patient via pyrosequencing and qPCR, the data indicate that 1) bacteria diversity can be high in CF patients not having an active infection, 2) while the presence of most taxa present in the lung change over time, a few specific pathogens are present in all samples, 3) bacterial diversity and abundance correlates with antibiotic treatment, and 4) standard antibiotic treatment does not remove all bacteria from the lung. Ongoing experiments are expanding these studies to analyze additional samples and include additional patients in the study.

Microbe Source Tracking.

Little is known about the fate of microbes released into the environment. How long do bacteria survive? What physiological changes do they undergo over time? How far and how fast do they travel through soils? Current methods to monitor changes in population profiles cannot answer these questions. Our research is attempting to monitor individual cells temporally and spatially to examine the movement, longevity, and physiological status of bacteria in the environment. This field is called bacterial, or microbe, source tracking (BST/MST). We are in the process of developing a BST method that can be used to identify the source of fecal contaminants in surface waters. In a pilot study awaiting final approval from the US EPA, a gfp-tagged natural E. coli isolate will be introduced into the subsurface area adjacent to a stream on campus. Samples collected from monitoring wells will be analyzed via PCR and microscopy for the presence of dead, culturable, and viable-but-nonculturable forms of the GMO. A patent on this BST method is currently under review and a biotechnology company, BioTrackers, Inc., was formed to explore the commercial applications of this method. The U.S. EPA has supported this research through SBIR funding.

Selected Publications

•   Yankson, K., and Steck, T.R. A Strategy for Extracting DNA from Clay Soil, and Detecting a Specific Target Sequence via Selective Enrichment and Real-Time (quantitative) PCR Amplification. 2009. Appl. Environ. Microbiol. 75(18):6017-6021.

•   Smith, J., Edwards, J., Hilger, H., and Steck, T.R. 2008. Sediment can be a reservoir for coliform bacteria released into streams. J. Gen. Appl. Microbiol. 54(3):173-179.

•   Steck, T. R. 2006. The viable but nonculturable condition in bacteria. Encyclopedia of Life Sciences. John Wiley & Sons, Ltd..

•   Anderson, M., Bollinger, D., Hagler, A., Hartwell, H., Rivers, B., Ward, K., and Steck, T. R. 2004. Viable but nonculturable bacteria are present in mouse and human urine specimens. J. Clin. Microbiol. 42(2):753-758

•   Grey, B., and Steck, T.R. 2001. Concentrations of copper thought to be toxic to Escherichia coli can induce the viable but nonculturable condition. Appl. Environ. Microbiol. 67(11):5325-5327.

•   Grey, B., and Steck, T.R. 2001. The viable but non-culturable state of Ralstonia solanacearum may be involved in long-term survival and plant infection. Appl. Environ. Microbiol. 67(9):3866-3872.

•   Rivers, B., and Steck, T.R. 2001. Viable but nonculturable uropathogenic bacteria are present in the mouse urinary tract following urinary tract infection and antibiotic therapy. Urol. Res. 29:60-66.

•   Ghezzi, J., and Steck, T.R. 1999. Induction of the viable but nonculturable condition in Xanthomonas campestris pv. campestris in liquid microcosms and sterile soil. FEMS Microbiol. Ecol. 30(3):203-208.

•   Alexander, E., Pham, D. and Steck, T.R. 1999. The viable but nonculturable condition is induced by copper in Agrobacterium tumefaciens and Rhizobium leguminosarum. Appl. Environ. Microbiol. 65(8):3754-3756.

Current Lab Members:

•   Deepika Gaddam. M.S. student. Research project - development of a new bacterial source tracking method.

•   Joshua Stokell. Ph.D. student. Research project - changes in microbial diversity in CF patients in response to antibiotic therapy.