title: Real-time bacterial microcolony counting using on-chip microscopy.
abstract: Observing microbial colonies is the standard method for determining the microbe titer and investigating the behaviors of microbes. Here, we report an automated, real-time bacterial microcolony-counting system implemented on a wide field-of-view (FOV), on-chip microscopy platform, termed ePetri. Using sub-pixel sweeping microscopy (SPSM) with a super-resolution algorithm, this system offers the ability to dynamically track individual bacterial microcolonies over a wide FOV of 5.7 mm × 4.3 mm without requiring a moving stage or lens. As a demonstration, we obtained high-resolution time-series images of S. epidermidis at 20-min intervals. We implemented an image-processing algorithm to analyze the spatiotemporal distribution of microcolonies, the development of which could be observed from a single bacterial cell. Test bacterial colonies with a minimum diameter of 20 μm could be enumerated within 6 h. We showed that our approach not only provides results that are comparable to conventional colony-counting assays but also can be used to monitor the dynamics of colony formation and growth. This microcolony-counting system using on-chip microscopy represents a new platform that substantially reduces the detection time for bacterial colony counting. It uses chip-scale image acquisition and is a simple and compact solution for the automation of colony-counting assays and microbe behavior analysis with applications in antibacterial drug discovery.
authors.affiliation: Department of Electrical Engineering, California Institute of Technology, Pasadena, CA 91125, USA.|Center for Environment, Health, and Welfare Research, Korea Institute of Science and Technology, Seoul 136-791, Republic of Korea.
authors.forename: Jae Hee
authors.initials: JH
authors.lastname: Jung
authors.affiliation: Han-River Environment Research Center, National Institute of Environmental Research (NIER), Yangpyeong-gun, Gyeonggi-do 476-823, Republic of Korea.
authors.forename: Jung Eun
authors.initials: JE
authors.lastname: Lee
mesh_terms: D000465:Algorithms; D057205:Automation, Laboratory / Q000295:instrumentation / Q000379:methods*; D015169:Colony Count, Microbial / Q000295:instrumentation / Q000379:methods*; D007091:Image Processing, Computer-Assisted; D056656:Lab-On-A-Chip Devices; D007909:Lenses; D008853:Microscopy / Q000295:instrumentation / Q000379:methods*; D013212:Staphylococcus epidermidis / Q000254:growth & development*; D013997:Time Factors