In recent years, food safety accidents by microbial contamination is a considerable threat to health. The rapid detection of microorganisms is of great significance to food safety. At present, the rapid microorganism detection technology is a difficult operation and high cost. Laser-induced fluorescence spectrometry (LIFS), with the advantages of high sensitivity, convenient operation, relatively cheap equipment, could provide a potential technique for rapid detection of microorganisms. In this paper, we use a portable 405 nm laserto excitefluorescence of three common foodborne pathogenic bacteria (Enterococcus faecalis, Salmonella Typhimurium and Pseudomonas aeruginosa), and a fiber spectrometerto detect the spectra. By adjusting the laser power (10 similar to 100 mW) to get the fluorescence intensity of Enterococcus faecalis, the relationship between the laser power and bacterial fluorescence intensity has been verified, and the result showed the optimal laser power range of 50 to 80 mW. In this experiment, the fluorescence spectra between bacterial samples are obtained at P = 50 mW. We discussed the relationship between bacterial structure and fluorescence spectra. According to the research result, It was concluded that E. faecalis exhibited a fluorescence peak of flavonoid groups near 528 nm, and the fluorescence peak at 634 nm of P. aeruginosa corresponds to the fluorescence emission of protoporphyrin. The results showed that, (1) the fluorescence peaks at 634 and 703 nm of P. aeruginosa for excitation are different from other two bacteria, which can be a feature for direct detection; (2) based on statistics, the spectrum of E. faecalis and S. Typhimurium was divided into 9 characteristic areas, and the recognition rate of the two bacteria reached 100% detected by the dynamic clustering method. The results show that the laser-induced fluorescence spectrometry can effectively detect P. aeruginosa, E. faecalis and S. Typhimurium. Compared with other rapid detection techniques, LIFS has significant application value for the rapid detection of foodborne pathogenic bacteria with the easier operation, faster detection speed and higher recognition rate.
