Defense Date


Document Type


Degree Name

Master of Science



First Advisor

Janina Lewis


Porphyromonas gingivalis, a gram-negative, anaerobic bacterium, is widely recognized as a causative agent for periodontal disease. Despite sequencing of the complete genome, no research exists examining gene regulation response in P. gingivalis to shifts in pH. Previous studies have shown that P. gingivalis is capable of surviving in the variety of micro- environmental niches found within the oral cavity, including basic and acidic pH conditions. However, the underlying mechanisms of this survival are not well understood. This study examined P. gingivalis by comparing bacteria shocked at three acidic to neutral pH conditions (5.5, 6.5 and 7.0) to bacteria vii shocked at pH 8.5. Using microarray to examine global gene expression, differential gene expression was identified in all conditions, with total genes differentially regulated ranging from 30 to almost 500 genes. Among these, genes for ammonia production, and cation gradients were found significantly up-regulated in acidic conditions, indicating a possible role in base creation and cation transport for survival of P. gingivalis in adverse pH conditions.


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Is Part Of

VCU Theses and Dissertations

Date of Submission

August 2010

Included in

Biology Commons