ABSTRACT
Abstract. The Agilent 4440 chemical sensor has been used to study several aspects of the growth of Escherichia coli. This instrument consists of an automated headspace sampler coupled to a quadrupole mass spectrometer and is designed to analyse the headspace of samples, in this case bacterial cultures, for their volatile composition over the mass range 46 to 550 daltons. The volatile signature has been investigated with respect to each growth phase as follows; lag: initiation of growth and macromolecular synthesis, exponential (or log): differentiation of signature with respect to metabolism (low mass ranges) and bacterial speciation (high mass ranges), stationary: categorisation of the bacterial population into growing, stressed and dormant cells. These objectives have been addressed using electrical flow impedance to determine cell size and number, and fluorescence to determine the physiological state of individual cells within the bacterial population. Principle component analysis shows that the volatile signature can be used to discriminate between the different growth phases with most of the variance contained within the mass range of 46 to 100 daltons.
