Research Interests

The introduction of molecular techniques to microbial research has provided new and fundamental insights into microbial communities and their activities. From the "black-box" approach of only a decade ago, in which all microbes were treated as if they were acted identically, we have progressed to an understanding that microbial communities are richly diverse, yet frequently dominated by a few species that recur in different parts of the world. In my own work, I have used molecular techniques to study the growth rate of individual marine bacterial cells in an effort to understand how bacteria react to changes in biological and physical processes, at both a community level and at the level of individual cells. Much of my work focuses on the use of molecular techniques to measure the ribosomal RNA content of individual bacterial cells and to interpret that measurement as an estimate of the growth rate of the individual cell.

Over the past decade, oceanographic research has increasingly utilized and depended on instrumented sampling. Physical and chemical variables are measured with high spatial and temporal resolution, thanks to the ability to collect data and process samples far faster than was previously possible. Advances in sensor and sample processing technologies have revolutionized oceanography, not least because of their enormous increase in sampling resolution. Studies of microbial processes have lagged far behind the technological revolution in oceanography. Most of the molecular tools are at least as laborious as their traditional microscope-based predecessors, and microbial research remains hampered by the lack of simple, rapid methods for intensive data gathering. To meet the need for more rapid data acquisition methods that can be applied to microbial process research, we have been working on the development of fiber-optical biosensors that detect nucleic acid hybridization. Using this new tool, we will be able to assess the abundance of particular microbial taxa, infer their growth rate, and evaluate which genetically-encoded metabolic processes are currently being expressed. Measurements will take minutes or even seconds rather than hours and days.

Selected Publications

Kemp, P.F., S. Lee, and J. LaRoche. 1993. Estimating the growth rate of slow-growing marine bacteria from RNA content. Appl. Environ. Microb. 59:2594-2601.

Lee, S., C. Malone, and P.F. Kemp. 1993. Use of multiple 16S rRNA-targeted fluorescent probes to increase signal strength and measure cellular RNA from natural planktonic bacteria, Mar. Ecol. Prog. Ser. 101:193-201.

Kemp, P.F., B.F. Sherr, E.B. Sherr, and J.J. Cole (Eds.). 1993. Handbook of methods in aquatic microbial ecology, Lewis Publishers, Chelsea, MI. 86 chapters, 777 pp.

Kemp, P.F., S. Lee, J. LaRoche. 1993. Evaluating bacterial activity from cell-specific ribosomal RNA content measured with oligonucleotide probes. In: Kemp, P.F., B.F. Sherr, E.B. Sherr, and J.J. Cole. (Eds.), Handbook of methods in aquatic microbial ecology, pp. 415-422. Lewis Publishers, Chelsea, MI.

Kemp, P.F. 1994. Microbial carbon utilization on the continental shelf and slope during the SEEP II experiment. Deep-Sea Res. II 41: 563-581.

Kemp, P.F., P.G. Falkowski, C. Flagg, W. Phoel, S. Smith, D.W.R. Wallace, C.D. Wirick. 1994. Modeling oxygen concentration and carbon flow during stratified spring and summer conditions on the continental shelf, Middle Atlantic Bight, eastern U.S.A. Deep-Sea Res. II 41: 629-655.

Anderson, R., G. Rowe, P.F. Kemp, S. Trumbore, P. Biscaye. 1994. Carbon budget for the mid-slope depocenter of the Middle Atlantic Bight. Deep-Sea Res. II 41: 669-703.

Lee, S., and P.F. Kemp. 1994. Single-cell RNA content of natural marine planktonic bacteria measured by hybridization with multiple 16S rRNA-targeted fluorescent probes. Limnol. Oceanogr. 39:869-879.

Kemp, P.F. 1994. A philosophy of methods development: the assimilation of new methods and information into aquatic microbial ecology. Microbial Ecology 28:159-162.

Kemp, P.F. 1995. Can we estimate bacterial growth rates from ribosomal RNA content? In: Joint, I., et al., Molecular Ecology of Aquatic Microbes, NATO ASI Series, 38:279-302.

Rappe, M.S., P.F. Kemp, S.J. Giovannoni. 1995. Abundant chromophyte plastid 16S ribosomal RNA genes found in a clone library from Atlantic Ocean seawater. J. Phycology 31:979-988.

Rappe, M.S., P.F. Kemp, S.J. Giovannoni. 1997. Phylogenetic diversity of marine coastal picoplankton 16S rRNA genes cloned from the continental shelf off Cape hatteras, N.C. Limnol. Oceanogr. 42:811-826.

Kerkhof, L., and P.F. Kemp. 1999. Small ribosomal RNA content in marine Proteobacteria during non-steady state growth. FEMS Microbial Ecology 30:253-260.

Sanders, R.W., U.-G. Berninger, E.L. Lim, P.F. Kemp and D.A. Caron. 2000. Mixo- and heterotrophic nanoplankton and their picoplankton prey on Georges Bank and in the Sargasso Sea. Mar Ecol Prog Ser 192:103-118.

Kemp, P.F. 2000. The CD Archive: 43 Years of Limnology and Oceanography. American Society of Limnology and Oceanography.

Aller, R.C., J.Y. Aller, and P.F. Kemp. 2001. Effects of particle and solute transport on rates and extents of remineralization in bioturbated sediments. In: Organism-Sediment Interactions (J.Y. Aller, R.C. Aller, and S. Woodin, eds.) Univ. S. Carolina Press, Columbio, S.C.

Kemp, P.F., J.Y. Aller. 2003. Bacterial diversity in aquatic systems: what can we learn from 16S rDNA libraries? FEMS Microbial Ecology (submitted).

Harbans S. Dhadwal, Paul Kemp, Josephine Aller, and M. Megan Dantzler, 2003. A Capillary Waveguide Nucleic Acid Based Biosensor, Anal. Chimica Acta (accepted)

Harbans S. Dhadwal, Paul Kemp, Josephine Aller (2003) Capillary Waveguide Fluorescence Sensor. Patent Application.