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(313a) How Conjugation Contributes to Antibiotic Resistance of Biofilm - from an Aspect of Population Balance Model with Stochastic Intracellular Gene Regulation

Ramkrishna, D., Purdue University
Shu, C., Purdue University

      In this work, a population balance model with stochastic intracellular gene
regulation is applied to analyze the important role of conjugation on biofilm
drug resistance. The transfer of conjugative plasmid helps bacteria spread
antibiotic resistance. Specifically, we focus on the conjugation of plasmid
pCF10, which is influenced by both pheromone, secreted by recipients, and
inhibitor, secreted by donors. Mass transfer effects in the biofilm alter the
ratio of pheromone to inhibitor of a cell, which  in turn influlences
the DNA configuration. Accordingly, the gene expression pattern is altered. Our
model predicts that biofilm has a pronounced effect on the induction of
conjugation.  Further, the planktonic
environment shows unimodal distributions around the on or off states, while the
biofilm environment shows bimodal distributions.  While the addition of inhibitor has only a
small effect on the biofilm, the effect on cells in planktonic growth is
substantial. These results offer a plausible explanation of biofilm antibiotic
resistance caused by conjugation.