Study On Near-infrared Sensitive Components From Escherichia Coli O157: H7and Listeria Monocytogenes

Food-borne disease is one of the most widespread health problems in the worldtoday, and food-borne bacterial pathogens are major cause of food-borne diseases.Escherichia coli O157:H7and Listeria monocytogenes are important food-bornepathogenic bacteria treated as detection index in pathogenic bacteria detection work.Because of the advantages of efficiency, non-destruction, and non-pollution, nearinfrared spectroscopy has been widely used in various research areas. This work tookEscherichia coli O157:H7and Listeria monocytogenes which in logarithmic phase asresearch objects, analyzed by principle component analysis (PCA), the result indicatesthat the two kinds of food-borne bacteria can specifically absorb near-infrared light.Based on previous research achievements about Escherichia coli O157:H7andListeria monocytogenes, two kinds of near infrared sensitive component of food-bornepathogenic bacteria were studied.The main results:1. This work took Escherichia coli O157:H7and Listeria monocytogenes whichin logarithmic phase as research objects, the two kinds of bacteria detected by FT-NIRafter the vacuum freeze drying. The near infrared spectrum were interpreted.2. Analyzed by PCA, the two kinds of food-borne bacteria can specifically absorbnear-infrared light. PCA shows that the extraction sums of squared loading of theprevious three principle components reaches87.22%.They could be identified with thefirst three principle components by PCA.3. Extracted and purified by improved hot phenol-water, the lipopolysaccharide(LPS) from E.coli O157:H7was detected by FT-NIR. The result of spectruminterpretation shows that the absorption peaks of LPS are at6798cm-1,5784cm-1,5661cm-1,5180cm-1,4403cm-1,4332cm-1,4260cm-1,4166cm-1,4058cm-1,4044cm-1.Comparatively analyzed with the near infrared spectrum of E. coli O157:H7, It is surethat the characteristic absorption peaks of LPS from E. coli O157:H7are at4403cm-1, 4332cm-1,4166cm-1. Windowed at the squared loadings,26characteristic wavelengthsof LPS from E.coli O157:H7in the near infrared region were got.4. Extracted by trichloroacetic acid (TCA), the peptidoglycan(PG) from Listeriamonocytogenes was detected by FT-NIR. The result of spectrum interpretation showsthat the absorption peaks of PG are at6670cm-1,5915cm-1,5779cm-1,5169cm-1,4874cm-1,4608cm-1,4358cm-1,4169cm-1,4054cm-1. Windowed at the squaredloadings,26characteristic wavelengths of PG from LM in the near infrared regionwere got.