This protocol details the construction of a simple, low-cost, small-scale, multiplex chemostat system designed for the continuous cultivation of microorganisms in suspension (i.e., bacteria, yeast, microalgae). The continuous culture device can operate at a working volume of 25 ml and allows the run of 8 chemostats in parallel by a single person. It provides a platform for parallel, long-term studies of evolution and adaptation of microorganisms under the stress of antimicrobial agents and/or toxic pollutants. The system complies with the varied needs of researchers for an accessible, highly-throughput and reliable tool that is nevertheless easy to construct, use and operate, and not demanding of space, materials, medium supply and workload. Here, we also validate the use of this system to generate de novo resistance towards a novel antimicrobial and a commonly used antibiotic in an antimicrobial-sensitive model organism. We believe that this "Do It Yourself" (DIY) system may constitute a useful tool to address the global problem of antibiotic resistance and to develop non-antibiotic based therapies.
