Microfluidic droplet reactors to reveal bacterial community interactions in an antibiotic environment

Antibiotics have been widely used in clinics to treat infections, caused by bacteria. However, misuse and abuse of antibiotics over the past decades have led to the emergence of massively drug-resistant microorganisms, which result in a dramatic decline in their efficacy and a large number of deaths. The spread of resistance in bacterial communities is not limited to gene transfer; cross-protection also plays a role. Cross-protection is one of the mechanisms by which different bacteria, sharing the same environment, protect each other to survive in the presence of antibiotics. To investigate the bacterial community interaction in an antibiotic environment, the microfluidic droplet reactors are used to track the survival status of co-cultured antibiotic-sensitive and strong antibiotic-resistant strains in an antibiotic (Cefotaxime, CTX) environment with various harsh degrees. Microfluidic reactor system monitors in real time the growth status of two bacterial strains by detecting their different emission fluorescent signals; E.coli YFP (antibiotic-sensitive) produces yellow fluorescent protein and E.coli BFP (strong antibiotic-resistant strain) produces the blue fluorescent protein. As the fluorescent intensity change during incubation of both strains, a phenomenon of cross-protection is observed in the low concentration of CTX (0.05-5 µg/mL). In addition, to confirm the effect of cross-protection, cell status is also investigated using microscopy, as well as from cell-free media and β-lactamase activity with a plate reader.