Many biological samples are aqueous suspensions of large molecules and even whole organisms, such as bacteria. IR spectroscopy of aqueous samples can be challenging due to the strong absorbance of water. Horizontal multibounce ATR, often combined with temperature control, gives sufficient sensitivity to the biological components of a sample whilst also allowing for careful spectral subtraction of the water signal. This note looks at the analysis of yeasts and yeast protoplasts using the Gateway 6-reflection ATR. Spectra were acquired from aqueous suspensions of yeast cells and a comparison was made between spectra of whole cells and of protoplasts, which are an important precursor for new genetic hybrids.
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