Smartphone-based rapid quantification of viable bacteria by single-cell microdroplet turbidity imaging

摘要: Standard plate count (SPC) has been recognized as the golden standard for quantification of viable bacteria. However, SPC usually takes one to several days grow individual cells into a visible colony, which greatly hampers its application in rapid bacteria enumeration. Here we present microdroplet turbidity imaging based digital (dSPC) method overcome this hurdle. Instead cultivating on agar plates, are encapsulated monodisperse microdroplets single-cell cultivation. Proliferation bacterial cell produced detectable change turbidity, allowed, after just few doubling cycles (i.e., hours), enumeration by visible-light imaging. Furthermore, dSPC platform integrating power-free droplet generator with smartphone-based was established. As proof-of-concept demonstrations, series Gram-negative (Escherichia coli) and Gram-positive (Bacillus subtilis) samples were quantified via smartphone accurately within 6 hours, representing detection sensitivity 100 CFU ml-1 at least 3 times faster. In addition, Enterobacter sakazakii (E. sakazakii) infant milk powder real sample enumerated contrast 24 hours needed traditional SPC. Results high accuracy reproducibility achieved, no difference counts found between By enabling label-free, rapid, portable low-cost cultivation onsite, forms basis temporally geographically trackable network surveying live microbes globally where every citizen cellphone can contribute anytime anywhere.