A Raman-microfluidic system for single bacterium identification, and sorting, and its application in bacterial properties analysis

BACKGROUND: Rapid and reliable bacterial detection is very important for both disease diagnosis and bacterial research, but the speed of bacterial detection is greatly affected by the fact that traditional detection methods require bacterial culture first. Therefore, it is eager to develop a single bacterium detection method that do not require culture. Raman spectroscopy is a promising approach to identify single bacterium, but it still faces two challenges: how to precisely control individual bacterium, and how to improve signal-to-noise ratio in the Raman measurement. RESULTS: To address these problems, we propose a Raman-microfluidic single bacterium identification and sorting method. A bi-directional flow controllable microfluidic system was designed to control bacteria movement, while a special S-shaped channel and a large laser spot ensured that the Raman spectrum of a single bacteria can be detected stably and with high quality on the move. The accuracy and repeatability of this detection system was verified, and a preliminary identification and sorting of bacterial drug resistance can be realized. In addition, Raman spectra of dozens of bacteria were obtained through this detection system, and based on these Raman spectra, multiple bacteria were identified. Their compositional and structural characteristics were further analyzed by the Raman features, which provided a reliable data base for future bacterial studies. SIGNIFICANCE AND NOVELTY: We built a Raman-Microfluidic system that can realize high-quality single bacterium identification and sorting. The Raman spectrum of a single bacterium can be detected stably and with high quality on the move. And a Raman spectral database of several bacterial species was preliminary established, which laid the foundation for the rapid bacterial identification. The establishment of our systems and databases is of great significance for rapid diagnosis of diseases and dynamic research on drug resistance.