Abstract
Bacteria culture is a basic technique in both fundamental and applied microbiology. The excessive reagent consumption and difficulty to maintain bulk bioreactors for microbial culture has prompted the development of the miniaturized on chip bioreactors. At microscopic scale, the low Reynold number fluidics justifies the design of a class of discrete chemostats of N compartment growth chamber to recapitulate two mechanistic aspects of a chemostat, namely continual supply of nutrient and dilution of microbial population. With the minimal choice of two compartment (N=2) and discrete time, periodic dilution steps, we realize a microfluidic chemostat that mimics the serial dilution transfer culture at macroscopic scale. This device supports automated, long term (~100 hr) microbial culture with nanoliter scale working volume and real time monitoring of microbial population at single cell resolution. Due to high surface to volume ratio, the device also serves an effective biofilm flow reactor to support a planktonic and biofilm ecology with proper choice of plumbing protocol. In the dilute biofilm limit, a simple chemostat model with wall growth fits well with the growth curves. We expect such devices will open opportunities in many fields of microbiology such as microbial ecology, antibiotic drug resistance study, and human microbiome, and biofilm study.