Title |
Autoinducer-2 detection among commensal oral streptococci is dependent on pH and boric acid |
Author |
Giancarlo A. Cuadra1*, Ashley J. Frantellizzi2, Kimberly M. Gaesser2, Steven P. Tammariello2, and Anika Ahmed1 |
Address |
1School of Math and Sciences, Lincoln Memorial University, Harrogate, TN, USA, 2Department of Biological Sciences, Binghamton University, Binghamton, NY, USA |
Bibliography |
Journal of Microbiology, 54(7),492-502, 2016,
|
DOI |
10.1007/s12275-016-5507-z
|
Key Words |
autoinducer-2, dental plaque, pH, streptococcus,detection, ecology |
Abstract |
Autoinducer-2, considered a universal signaling molecule, is
produced by many species of bacteria; including oral strains.
Structurally, autoinducer-2 can exist bound to boron (borated
autoinducer-2). Functionally, autoinducer-2 has been linked
to important bacterial processes such as virulence and biofilm
formation. In order to test production of autoinducer-2 by a
given bacterial strain, a bioassay using marine bioluminescent
bacteria Vibrio harveyi as a reporter for autoinducer-2
has been designed. We hypothesize that pH adjustment and
addition of boron are required for optimal bioluminescence
and accurate autoinducer-2 detection. Using this reporter
strain we tested autoinducer-2 activity from two oral commensal
species, Streptococcus gordonii DL1 and Streptococcus
oralis 34. Spent broth was collected and adjusted to pH 7.5
and supplemented with boric acid prior to measuring autoinducer-
2 activity. Results show that low pH inhibits bioluminescence
of the reporter strain, but pH 7.5 allows for bioluminescence
induction and proper readings of autoinducer-2
activity. Addition of boric acid also has a positive effect on
bioluminescence allowing for a more sensitive detection of
autoinducer-2 activity. Our data suggests that although autoinducer-
2 is present in spent broth, low pH and/or low levels
of boric acid become an obstacle for proper autoinducer-2
detection. For proper autoinducer-2 detection, we propose a
protocol using this bioassay to include pH adjustment and
boric acid addition to spent broth. Studies on autoinducer-2
activity in several bacteria species represent an important area
of study as this universal signaling molecule is involved in
critical bacterial phenotypes such as virulence and biofilm
formation. |