Research Interests

My microbiology research program targets two areas. One area is concerned with hyperthermophilic archaea and the other with pathogenic enteric bacteria.

The project on hyperthermophiles reflects the fundamental discovery based on 16S rRNA sequence analysis that all life can be divided into three groups, archaea, bacteria and eukaryotes. The Archaea are subdivided into the Euryarchaeota and the Crenarchaeota. Hyperthermophiles are present in both subdivisions and their 16S rDNA is uniformly deeply rooted suggesting they arose early in the history of our planet. Archaea are distantly related to Eukaryotes, but there is remarkable conservation between their methods for information processing. This includes making, repairing and degrading, DNA, RNA and protein. Archaeal prokaryotes are distinct in this regard from bacterial prokaryotes. Our lab is studying what regulates archaeal gene expression. One project uses mercury resistance genes to assay positive and negative regulation of transcription, another focuses on the function of multiple basal transcription component TFB (TFIID homolog), the third focuses on catabolite repression. To get at these questions we use a variety of methods including, genomics, proteomics, molecular biology, microbial physiology, biochemistry and genetics. Most studies use the aerobic hyperthermophile, Sulfolobus solfataricus which we grow at 80C (176F) at a pH of 3. Many studies are conducted in the laboratory but a significant component involves field studies at various hot springs where we study questions concerning the molecular microbial ecology of life at high temperatures.

The project on pathogenic enteric bacteria focuses on how these organisms survive and evolve during wastewater treatment. Since the public continues to be threatened by new and emerging enteric pathogens we are studying the role of municipal wastewater as an environment which might influence this process. To do this we have developed several new methods for looking at the identity and physiology of uncultivated bacteria using fluorescent antibody and nucleic acid probes. This allows us to understand what these organisms are doing in "real time" and differs radically from the traditional culture-based approach generally employed in microbiology.

Recent Publications

• Ponniah, G., H. Chen, R. Michielutti, N. Salonen and P. Blum. 2003. Single cell protein profiling of wastewater enterobacterial communities predicts disinfection efficiency. Appl. Environ. Microbiol. (In Press),
• Worthington, P., V. Hoang, P. Perez-Pomares, and P. Blum. 2003. Targeted disruption of the a- amylase gene in the hyperthermophilic archaeon Sulfolobus solfataricus. J. Bacteriol. 185:482- 488.
• Worthington, P., P. Blum, F. Perez-Pomares, and T. Elthon. 2003. Large scale cultivation of acidophilic hyperthermophiles for recovery of secreted proteins. Appl. Environ. Microbiol. 69:252-257.
• Bini, E., V. Dikshit, K. Dirksen, M. Drozda, and P. Blum. 2002. Stability of mRNA in hyperthermophilic archaea. RNA 8:1129-1136.
• Blum, P. and V. Dikshit. 2002. Archaea. In "Desk Encyclopedia of Microbiology", M. Schaechter (ed). Academic Press, New York.
• Blum, P. 2001. (Ed.), Archaea, ancient microbes, extreme environments and the origin of life. Adv. Appl. Microbiol. vol. 50, pp. 1-382. Academic Press, New York.
• Bini, E., and P. Blum. 2001. Archaeal catabolite repression: a gene regulatory paradigm. Adv. Appl. Microbiol. 50: 339-366.
• Haseltine, C., T. Hill, R. Montalvo-Rodriguez, S. Kemper, R. Shand, and P. Blum. 2001. Secreted euryarchaeal microhalocins kill hyperthermophilic crenarchaea. J. Bacteriol. 183: 287-291.
• Montalvo-Rodriguez, R., C. Haseltine, K. Huess-LaRossa, T. Clemente, J. Soto, P. Staswick and P. Blum. 2000. Autohydrolysis of plant polysaccharides using transgenic hyperthermophilic enzymes. Biotechnology and Bioengineering 70:151-159.
• Haseltine, C., R. Montalvo-Rodriguez, A.Carl, E. Bini and P. Blum. 1999. Extragenic pleiotropic mutations that repress glycosyl hydrolase expression in the hyperthermophilic archaeon Sulfolobus solfataricus. Genetics 152:1353-1361.