Dr. David White:
Center for Biomarker Analysis;
UT Department of Microbiology
Protection from Microbial Contamination
Microbial communities have long fascinated David White . . . how microbes survive the anaerobic, high-pressure living conditions deep inside the Earth or near scalding, acidic oceanic vents; how they turn vital processes on or off at precisely the right moment.
One way microbes communicate is through a process known as 'quorum sensing'. Here, each cell in a microbial community steadily makes small diffusible molecules of a particular substance. As the molecules diffuse through the cell wall into the surrounding area, their concentration builds. When it reaches a threshold level, the concentrated molecules trigger removal of a repressor, and a new process begins. Some molecules, for example, induce bacteria to take up foreign genes or to make spores, showing microbial communities exchange chemical signals much like our own cells. A similar type of inducement, in the presence of a greater than threshold concentration, is seen in humans at the onset of puberty.
White's research focuses specifically on ultrasensitive methods for detecting microorganisms in indoor air, plant and animal infections, drinking water pipes, contaminated aquifers, oceanic hydrothermal vents, and deep subsurface environments. In 1998, he was named a Visiting Distinguished Scientist at the Jet Propulsion Laboratory in Pasadena, joining the team responsible for keeping Earth's microscopic stowaways from jeopardizing the search for extraterrestrial life on the Mars 2003 and 2005 missions.
White's group is responsible for biotechnology that detects patterns of fatty lipids in cell membranes specific to particular organisms. Fatty acids are found in all cell membranes. Known patterns can be used as biomarkers for these organisms. The detection of contamination for planetary protection of space probes is a natural extension of this work.
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