Document Type


Date of Award


Degree Name

Master of Science (MS)



First Advisor

Pere Miro, Bess Vlaisavljevich


Biofilms are the default state of microbial life and their formation on surfaces influences many processes. The coordinated behavior of microorganisms including their growth into biofilms occurs through a process termed quorum sensing during which they excrete specific signaling molecules called autoinducers. Recently it has been observed that Ag+ and Cu2+ ions interact with N-hexanoyl-L-homoserine autoinducers thereby inhibiting quorum sensing. Such inhibitors are called quorum quenchers. In this study, we have used density functional theory (DFT) calculations to study the ion pairing between select cations and short chained N-acyl-homoserine lactone (AHL) type autoinducers that are used by gram negative bacteria. We demonstrate that pairing of the cations to these autoinducers occurs at the carbonyl groups and examine how different R groups effect this interaction. The binding motifs with higher denticity resulted in stronger DFT pairing energies. DFT calculations showed that the carbon chain length has little impact on the strength of the ion pairing energy for a contact ion pair when it was varied from 2 to 4 carbons for the studied autoinducers. Ca2+ was the only ion studied that did not have a favorable contact ion pair at the DFT level of theory.

Subject Categories



Biofilms, Quorum Quenching

Number of Pages



University of South Dakota

Included in

Chemistry Commons