Sensoriamento ótico da dinâmica do crescimento de colônias de escherichia coli em ambiente hídrico

Abstract

This work is a study using two optical techniques to monitor the growth of cultures of Escherichia coli strains in two liquid culture medium: Raman spectroscopy and UV-Vis absorption spectroscopy (turbidimetry). In one hand, turbidity allows evaluating the different phases of growth of a bacterial culture (lag, exponential, stationary and decay) by optical density, measured with an UV-VIS spectrometer. On the other hand, Raman scattering (measured with a dispersive spectrometer) from contaminated water samples not only provides information about the grow phases, but also opens a possible identification of bacterial by its characteristic fingerprint. Two strains of E. coli (named as H2 / 11 and H3C2 / 12) were measured in liquid nutrient broth and four E. coli strains (named H2 / 11, H3C2 / 12, 109 and 110) in EC liquid broth, kept at 37.0 ° C over 24 hours. Aliquots of the samples were removed from the culture at regular time intervals for spectral measurements. The turbidity analysis allowed to measure the generation time, which was higher for strains grown in EC broth. Raman spectra provided information about the time evolution of the bands at 942 cm-1, 977 cm-1, 1036 cm-1, 1086 cm-1, 1140 cm-1, 1188 cm-1, 1182 cm-1, 1207 cm-1 e 1251 cm-1, associated with fingerprints of biological components. Data were analyzed by Principal Component Analysis (PCA). These results of both techniques allowed identifying the phases lag, exponential and stationary of the studied strains.