Effects of simulated microgravity on Streptococcus mutans oxidative stress tolerance & survival

Cybill Winkel

Authors:  Cybill Winkel, Matthew Hauserman, Ke Aira Davis, & Kelly C. Rice

Faculty Mentor: Kelly C. Rice

College:  College of Agricultural and Life Sciences


Due to several factors, including spaceflight osteopenia, decreased saliva production, and immune dysfunction, astronauts are at an increased risk of dental caries. Streptococcus mutans is a commensal pathogen, contributes to tooth decay, and exhibits altered physiology when cultured under simulated microgravity conditions. 
A set of experiments were conducted to investigate the effects of simulated microgravity on oxidative stress tolerance, one of the more well-characterized virulence factors of S. mutans. HARVS (High-Aspect Rotating Vessels) were inoculated with S. mutans UA159 and incubated using two microgravity models (Rotary Cell Culture System vs. Random Positioning Machine), with normal gravity controls. Samples were harvested at endpoints corresponding to mid exponential and late exponential growth phases. Each sample was treated with H2O2. At 30-minute intervals, samples were diluted, plated, and incubated. Time-dependent and dose-dependent effects were observed in the oxidative stress assays. Mid-exponential RCCS cultures were generally more sensitive to oxidative stress compared to late-exponential cultures. Differences were also observed in oxidative stress tolerance between the RPM and RCCS microgravity models, particularly in cultures harvested at late exponential growth.

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7 Responses
  1. Jennifer Drew

    Hi Cybill, Great job with the presentation! Such an interesting topic and you explain the methods really well.

    1. Cybill Winkel

      Thanks! Background/Methods are some of the trickier sections to describe to a general audience (in my opinion), so I’m glad to hear that. 😀

  2. Dylan Burgin

    Hi Cybill, good job! is there a particular microgravity model (RCCS vs RPM) that is more characteristic of the space environment?