Figure 1.

A novel ex vivo gastrointestinal model can maintain typical commensal cultures. A schematic of (a) A Bioreactor Imitation of Microbiota Ecosystem (ABIOME) shows the main bioreactor unit being connected to a computer controlled pumping system from each of the input solutions: pancreatic solution, base, acid and simulated “food”. The food and pancreatic solution inputs are controlled as a thrice-daily feed cycles while the acid and base maintain the pH set-points of the bioreactor at a pre-set ramp rate. With the feeding cycles, there is a thrice daily “waste harvest” where a portion of the bioreactor contents is removed to circulate wastes. The bioreactor unit is kept under strict anaerobic conditions via constant nitrogen sparging while the contents are constantly agitated by the stirring system. Using this system of feeding and pH control, monocultures of (b) the aerobic L. plantarum and (c) anaerobic B. longum reached a steady-state level after several hours of incubation. Cultures were inoculated in the food source at − 16, − 8 and 0 h, emulating the thrice daily feeding, after which the maintenance of the cultures was observed for 88 h. Cultures were enumerated with serial dilutions and plating on MRS and MRS-cysteine plates, respectively, following calculation of the number of colony forming units (CFU) per milliliter. Each time point represents n = 3 independent trials  +/− SEM.