Building A Turbidostat To Analyze Gut Microbiota Succession In Infants

Abstract

By continually supplying nutrients, a turbidostat presents a steady environment to analyze bacterial growth dynamics. This makes it possible to model microbial community succession in a simple and more realistic way than is possible with batch culture. The problem with current commercial turbidostats are their industrial size and price. With the use of 3D printed parts, printed circuit boards and laser cut pieces, all readily obtained online and in collaboration with laboratories here at McMaster University, I've created a relatively cheap custom turbidostat, ideally suited for longitudinal studies of microbial consortia that can accommodate eight separate experiments simultaneously. I have modified the design to enable microbial growth at 37°C under anoxic conditions, by changing how the growth media and gas is handled. I have also improved sample collection to make it more convenient and flexible. Cell growth dynamics were interrogated separately with one strain of a facultative anaerobe (E. coli) and one strain of an obligate anaerobe (Bacteroides thetaiotaomicron) bacteria. For the individual strains, real-time optical density and dilution rate vs time graphs were created showing that these microbes can be reproducibly cultured, holding steady optical density rates for extended periods of time. Future directions include culturing a complex community without contamination by inoculating the system with microorganisms from an infant stool sample. Community composition and metabolite dynamics could then be analyzed by sampling over time.