Application of nuclear magnetic resonance spectroscopy to analysis of ethanol fermentation kinetics in yeasts and bacteria

Nuclear Magnetic Resonance (NMR) spectroscopy is proving to be a very valua ble technique for characterizing the metabolic status of a range of microbi al fermentations. This non-invasive method allows us not only to determine the presence of particular metabolites, but also to monitor reaction rates, enzyme activities and transport mechanisms in vivo. Despite the low levels of the carbon-13 isotope (1.1%), natural-abundance C-13-NMR studies have p roven useful in monitoring the progress of various fermentation processes. Furthermore, P-31-NMR can provide noninvasive information relating to cellu lar metabolism, and on the energy status of the cells. This results from th e facility with NMR to identify various nucleotide phosphates and other ene rgy-rich compounds in the cell, as well as to characterize changes in the i ntracellular pH from the chemical shifts of internal phosphate and other ph osphorylated intermediates. In this review, we will summarize the use of NM R as an analytical tool in biotechnology and also discuss examples that ill ustrate how NMR can be used to obtain significant information on the charac teristics of ethanol fermentations in both yeasts and bacteria.