title: An automatic microturbidostat for bacterial culture at constant density.
abstract: We have developed a microturbidostat for long time bacterial culture at constant density controlled by optical detection and integrated pneumatic valves. The device was fabricated by multilayer soft lithography and in-situ formation of an agarose filter. The culture chamber of bacteria was connected in one side to a single bacterial input-output channel and in another side to a nutrient channel in which the agarose filter was formed to ensure the diffusion of nutrients and metabolites without bacterial loss. The bacterial number in the culture chamber was determined by measuring the fluorescence intensity of GFP proteins of the bacteria and the redundant bacteria could be exported automatically through the input-output channel with integrated micro-valves. In order to optimize the operation performance, we investigated the bacterial exportation efficiency with different input-output channel widths. As expected, the bacterial sorting coefficient was proportional to the input-output channel width. The results also showed that with a 20 microm channel-width, a long time culture was possible with a constant bacterial number in the chamber in the range from 400 to 700.
authors.affiliation: Center for Microfluidics and Nanotechnology and School of Physics, The State Key Laboratory for Artificial Microstructures and Mesoscopic Physics, Peking University, Beijing, 100871, China.
authors.forename: Xianjia
authors.initials: X
authors.lastname: Luo
authors.forename: Kangyang
authors.initials: K
authors.lastname: Shen
authors.forename: Chunxiong
authors.initials: C
authors.lastname: Luo
authors.forename: Hang
authors.initials: H
authors.lastname: Ji
authors.forename: Qi
authors.initials: Q
authors.lastname: Ouyang
authors.forename: Yong
authors.initials: Y
authors.lastname: Chen
mesh_terms: D019149:Bioreactors / Q000382:microbiology*; D002452:Cell Count / Q000295:instrumentation*; D018929:Cell Culture Techniques / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D004926:Escherichia coli / Q000502:physiology*; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation*; D012371:Robotics / Q000295:instrumentation*; D013050:Spectrometry, Fluorescence / Q000295:instrumentation*