The phenotypic responses of E. coli cells exposed to 1.2% (v/v) of 1-butanol, 2-butanol, isobutanol, tert-butanol, and 1,4-butanediol were studied in near real-time using Raman spectroscopy. A method of “chemometric fingerprinting” was employed that uses multivariate statistics (principal
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The phenotypic responses of E. coli
cells exposed to 1.2% (v
) of 1-butanol, 2-butanol, isobutanol, tert
-butanol, and 1,4-butanediol were studied in near real-time using Raman spectroscopy. A method of “chemometric fingerprinting” was employed that uses multivariate statistics (principal component analysis and linear discriminant analysis) to identify E. coli
phenotypic changes over a 180 min post-treatment time-course. A toxicity study showed extreme variability among the reduction in culture growth, with 1-butanol showing the greatest toxicity and 1,4-butanediol showing relatively no toxicity. Chemometric fingerprinting showed distinct phenotype clusters according to the type of alcohol: (i) 1-butanol and 2-butanol (straight chain alcohols); (ii) isobutanol and tert
-butanol (branched chain alcohols); and (iii) control and 1,4-butanediol (no terminal alkyl end) treated cells. While the isobutanol and tert
-butanol treated cells led to similar phenotypic responses, isobutanol was significantly more toxic. In addition, the phenotypic response was found to take place largely within 60 min of culture treatment; however, significant responses (especially for 1,4-butanediol) were still occurring at 180 min post-treatment. The methodology presented here identified different phenotypic responses to seemingly similar 4-carbon alcohols and can be used to study phenotypic responses of virtually any cell type under any set of environmental conditions or genetic manipulations.