title: Automated Chemotactic Sorting and Single-cell Cultivation of Microbes using Droplet Microfluidics.
abstract: We report a microfluidic device for automated sorting and cultivation of chemotactic microbes from pure cultures or mixtures. The device consists of two parts: in the first part, a concentration gradient of the chemoeffector was built across the channel for inducing chemotaxis of motile cells; in the second part, chemotactic cells from the sample were separated, and mixed with culture media to form nanoliter droplets for encapsulation, cultivation, enumeration, and recovery of single cells. Chemotactic responses were assessed by imaging and statistical analysis of droplets based on Poisson distribution. An automated procedure was developed for rapid enumeration of droplets with cell growth, following with scale-up cultivation on agar plates. The performance of the device was evaluated by the chemotaxis assays of Escherichia coli (E. coli) RP437 and E. coli RP1616. Moreover, enrichment and isolation of non-labelled Comamonas testosteroni CNB-1 from its 1:10 mixture with E. coli RP437 was demonstrated. The enrichment factor reached 36.7 for CNB-1, based on its distinctive chemotaxis toward 4-hydroxybenzoic acid. We believe that this device can be widely used in chemotaxis studies without necessarily relying on fluorescent labelling, and isolation of functional microbial species from various environments.
authors.affiliation: Department of Chemistry, Renmin University of China, Beijing 100872, China.|State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Libing
authors.initials: L
authors.lastname: Dong
authors.affiliation: State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Dong-Wei
authors.initials: DW
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Shuang-Jiang
authors.initials: SJ
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Wenbin
authors.initials: W
authors.lastname: Du
mesh_terms: D057205:Automation, Laboratory / Q000379:methods*; D001419:Bacteria / Q000254:growth & development* / Q000302:isolation & purification*; D018407:Bacterial Physiological Phenomena; D001431:Bacteriological Techniques / Q000379:methods*; D002633:Chemotaxis; D044085:Microfluidics / Q000379:methods*