Title: Survival of Methylobacterium aquaticum in Dental Waterlines at Constant Temperatures
Edwin Tsang (Presenter)
Lauritz Jensen, Midwestern University
Denise Olivas, Midwestern University
John Mitchell, Midwestern University
Objectives: Methylobacterium aquaticum, a biofilm producing bacterium, is a water-borne micro-organism that is present in many city water supplies. Immunocompromised patients may be adversely affected by this organism that is highly resistant to chlorine disinfection solutions. It is not routinely detected in most waterline testing, not because it is absent, but rather because it grows very slowly at 37C and is normally outcompeted by other organisms. This project investigated the bionomics of this bacterium, to determine the effects of various constant temperatures on the survivability of M. aquaticum.
Methods: Municipal water samples were assayed for the presence of M. aquaticum using 16S rRNA gene sequencing technology. A pure sample of the bacterium was isolated and prepared on R2A agar. Samples of the inoculum were suspended in RO water to an optical density (OD) of 0.10 at 625nm (biospectrophotometer). Prepared samples were stored at constant temperature (25, 30, 35, 40, and 45C) for up to 16 days. Aliquots were withdrawn on days 1,2,4,8, and 16. These samples were serially diluted and plated in triplicate, and incubated at 37C for 4 days. Growth of the bacteria was measured (CFU/mL) at each interval and compared to determine the survivability of the M. aquaticum at these different temperatures.
Results: M. aquaticum at 40 and 45C indicated rapid cell death by day 1-2 as compared to samples maintained at 25, 30 and 35C. Bacterial counts (CFU/mL) indicate 99.99% reduction of M. aquaticum by day 4 at 45C constant temperature.
Conclusions: The bionomics of M. aquaticum has not been previously reported and further investigation of this microorganism will determine any implications this may have in dental healthcare settings. Our study has determined possible temperatures that may aid to control the infiltration of M. aquaticum and other possible contaminants of dental unit water lines.