My group has developed an active and internationally recognized research program in two areas - environmental infection control in dental operatories and the ecology, molecular biology and taxonomy of the unique predatory bacteria of the family Bdellovibrionaceae, which may play a role in bacterial mortality and the control of bacterial populations in the environment. The role of bdellovibrios in nature and the organism's potential use as an agent of biological control has eluded investigators for over 40 years. Decades of studying these bacteria in water samples from rivers, oceans and seas has yielded small numbers of the organisms and limited data. Pioneering studies in our laboratory have revealed the primary habitat for these organisms to be the biofilm on surfaces in the aquatic environment and not the water. Our ultimate goal is to uncover the role of these organisms in nature, specifically the aquatic environment, and in infections. We have studied extensively the phylogeny of the organisms as determined by analyses of the sequences of the 16S rRNA and other genes. These efforts have led to the establishment of a new genus, Bacteriovorax, within the family Bdellovibrionaceae. We now have evidence based on analyses of a large part of the 16S rRNA gene, that the marine and halophilic bdellovibrios should be re-assigned to another genus Our group has been the most active in publishing on the bdellovibrios during the last decade. Current work involves continued studies on the molecular diversity and phylogenetic relationships of the Bdellovibrionaceae and like-organisms, the taxonomic classification of the organisms and the distribution patterns of specific phylotypes in aquatic systems.
The importance of environmental infection control is apparent when it is considered that this issue has had a greater impact on the practice of dentistry today, generating more publicity and causing more public consternation during the last decade than any other. Recent work in my laboratory in this area has focused on the microbial contamination of the dental water supply (DUWS). We have published the most papers on this topic. This work has contributed to the knowledge that water from the syringe and handpiece of nearly all dental units currently in use is massively contaminated with bacteria including potential pathogens. We have confirmed that the source of these organisms is the biofilm that forms on the inner walls of the plastic water distribution tubing of dental units. Our research team was the first to demonstrate the nature of biofilm development in dental units and yielded important clues as to the source of microorganims that become established in devices in dental operatories.. Our group's evaluation of dental units with a self-contained sterile water supply, which also revealed the sources of contamination, was a pioneering effort. Our research efforts have had national impact by providing supporting data and a basis for recommendations by the Centers for Communicable Diseases and the American Dental Association that all dental units be equipped to deliver water with not more than 500 colony forming units per ml.
We also have a strong emphasis on diversity in our laboratory and the development of students traditionally underrepresented in the sciences. This effort has been nationally recognized through several awards including the American Society for Microbiology William A. Hinton Award presented to me in recognition of the training of students including minority individuals. In February, 2004 I was awarded the University of Maryland, Baltimore Martin Luther King, Jr. Award in recognition of my efforts to promote inclusion and diversity in the sciences.
A partial listing of the more than 40 papers from our laboratory is listed below. For more information please go the link to view my CV.
Baer, M., Ravel, J., Chun, J., Hill, R., and Williams, H. N.. (2000). A proposaal for the re-classification of Bdellovibrio stolpii and of Bdellovibrio starrii into a new genus, Bacteriovorax gen. nov. as Bacteriovorax stolpii comb. nov. and Bacteriovorax starrii comb. nov., respectively. Intl. J. Sys. Evol. Microbiol. 50, 219-224.
Snyder, A. R., Williams, H.N., Baer, M. L., Walker, K. E., and Stine, O. C. (2002). 16S rDNA sequence a Analysis of environmental Bdellovibrio-and-like organisms (BALO) reveals extensive diversity. Internat. J. Syst.Evol. Microbiol., 52, 2089-2094.
Williams, H. N., and Baer, M.L. (2003). Bacteriovorax. In Brenner, Krieg, Staley and Garrity (Editors), The Proteobacteria, Bergey's Manual of Systematic Bacteriology, 2nd Edition, Volume 2, Springer-Verlag, New York, NY, in press
Smith, R. S., S. A. Pineiro, R. Singh, E. Romberg, M. E. Labib and H. N. Williams. 2004. Discrepancies in Bacterial Recovery from Dental Unit Water Samples on R2A Medium and a Commercial Sampling Device. Curr. Microbiol. 48: 243-246
Chauhan A., and Henry N. Williams. (2006). Response of Bdellovibrio and Like Organisms (BALOs) to the Migration of Naturally Occurring Bacteria to Chemo Attractants. In Press.
Dr. Williams has published over 80 papers and abstracts in scientific journals.
|Florida A&M University – Environmental Sciences Institute
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