Quantification of bacterial cells based on autofluorescence on a microfluidic platform

• Published in: Journal of Chromatography A 2008-02, Vol.1181 (1), p.153-158
• Main Authors: Bao, Ning, Jagadeesan, Balamurugan, Bhunia, Arun K., Yao, Yuan, Lu, Chang
• Format: Article
• Language: English
• Subjects: Autofluorescence; Bacteria - isolation & purification; Bacteriological methods and techniques used in bacteriology; Bacteriological Techniques; Bacteriology; Biological and medical sciences; Colony Count, Microbial - methods; Electrical lysis; Electrophoresis; Enumeration; Escherichia coli; Escherichia coli O157 - isolation & purification; Fluorescence; Fundamental and applied biological sciences. Psychology; Laser-induced fluorescence; Listeria monocytogenes; Listeria monocytogenes - isolation & purification; Microbiology; Microfluidic Analytical Techniques; Microfluidics; Salmonella enteritidis; Salmonella enteritidis - isolation & purification
• ISSN: 0021-9673
• DOI: 10.1016/j.chroma.2007.12.048

Bacterial counts provide important information during the processes such as pathogen detection and hygiene inspection and these processes are critical for public health and food/pharmaceutical production. In this study, we demonstrate the quantification of the number of bacterial cells based on the autofluorescence from the cell lysate on a microfluidic chip. We tested three model pathogenic bacteria ( Listeria monocytogenes F4244, Salmonella Enteritidis PT1 and Escherichia coli O157:H7 EDL 933). In the experiment, a plug of ∼150 pL containing lysate from 240 to 4100 cells was injected into a microfluidic channel with downstream laser-induced fluorescence detection under electrophoresis conditions. We found that the autofluorescence intensity increased with the number of cells almost linearly for all three bacteria. The autofluorescence remained a single peak when the cell lysate contained a mixture of different bacterial species. We also demonstrate a simple microfluidic device that integrates entrapment and electrical lysis of bacterial cells with fluorescence detection. Such a device can carry out the quantification of bacterial cells based on lysate autofluorescence without off-chip procedures. This study offers a simple and fast solution to on-chip quantification of bacterial cells without labeling. We believe that the method can be extended to other bacterial species.