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Differentiation of live, dead and treated cells of Escherichia coli O157:H7 using FT‐IR spectroscopy
Author(s) -
Davis R.,
Deering A.,
Burgula Y.,
Mauer L.J.,
Reuhs B.L.
Publication year - 2012
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1111/j.1365-2672.2011.05215.x
Subject(s) - escherichia coli , microbiology and biotechnology , enterobacteriaceae , bacteria , spectroscopy , chemistry , biology , biochemistry , genetics , gene , physics , quantum mechanics
Abstract Aims: To apply specific collection techniques and spectroscopy to differentiate between live and dead Escherichia coli O157:H7 cells, as well as cells subjected to various inactivation treatments, including heat, salt, UV, antibiotics and alcohol. Methods and Results: Fourier transform‐infrared (FT‐IR) spectroscopy was used to analyse E. coli O157:H7 cells, after filtration or immunomagnetic collection. Partial least squares analysis of the spectra quantified live E. coli O157:H7 in the presence of dead cells with an R 2 > 0·996. Canonical variate analysis (CVA) not only differentiated between spectra of 100% dead and 100% live cells but also between 1% live : 99% dead and 100% dead. CVA using principal components also differentiated between the spectra of the differentially treated cells at a 95% confidence level, and Cooman plots showed clear separation between clusters of spectra of bacteria exposed to the different inactivation treatments. Mahalanobis distances (MD) corroborated the results of CVA. Conclusions: These results demonstrated the effectiveness of rapid cell collection and FT‐IR spectroscopy techniques to differentiate between live and dead E. coli O157:H7 cells. Significance and Impact of the Study: This technique has potential applications for use with foods subjected to various inactivation treatments.