A grant has been awarded to Dr. Mark O. Martin of Occidental College to study the genetics of the bacterial predator Bdellovibrio bacteriovorus. This unusual microbe exists in two forms: a free swimming phase in search of other Gram negative bacterial prey cells to attack and invade, and an intraperiplasmic growth phase between the inner and outer membranes of prey cells. Different genes are expressed in each portion of the life cycle of Bdellovibrio, and this project proposes to investigate these "predation" genes. A combination of functional complementation, reporter gene technology, transposon mutagenesis, and other molecular biological tools will be used to investigate the genetics of this fascinating bacterium. A previously identified and unexpected alpha amylase gene from Bdellovibrio will be characterized with regard to structure, function, relationship to other amylases, and temporal expression throughout the organism's lifecycle. In addition, transposon mutagenesis and in vivo expression technology will be used to identify and characterize Bdellovibrio genes involved with predation and intraperiplasmic growth.
It is expected that bacterial predation will be found to play a significant role in microbial ecology and population structure; thus, intensive study of Bdellovibrio will be an important first step in understand the roles that microbial predators play in nature. The compartment in which Bdellovibrio grows and reproduces, the periplasm of prey cells, is unusual and difficult to study. Bdellovibrio's adaptations to this environment will shed light on the nature of the periplasm in ways that cannot easily be matched by in vitro studies. Additionally, the periplasmic life style of Bdellovibrio may show relationships to the diverse strategies used by bacteria that cause disease in animals and plants. Importantly, this proposal involves undergraduate students at every step. Because of the demographics of Occidental College, this grant will provide many opportunities for students from diverse backgrounds, including underrepresented minorities, to explore a unique research system. Additionally, the techniques used in this proposal will be incorporated into the laboratory portions of relevant courses, to give all students the opportunity to explore microbial genetic analysis: how research is actually carried out, and how results are interpreted, evaluated, and presented.
