W. Zeroual et al., FT-IR SPECTROSCOPIC STUDIES ON MOLECULAR-INTERACTIONS OF CRYOPROTECTANT AGENTS WITH BACTERIA, Biospectroscopy, 1(6), 1995, pp. 365-373
Fourier transform infrared spectroscopy was used to investigate, witho
ut any destructive interference, interactions of the cryoprotective ag
ents, glycerol and dimethyl sulfoxide with Bradyrhizobium japonicum. T
he intracellular spectrum of glycerol, obtained by subtracting the spe
ctrum of control bacteria from that of glycerol-treated bacteria, show
ed no differences in infrared features compared to that of pure glycer
ol. This was not the case when dimethyl sulfoxide treatment was used.
The intracellular spectrum displayed important modifications compared
to that of the pure chemical. Spectral analysis showed that glycerol a
nd dimethyl sulfoxide uptake required only a few minutes. Moreover, th
e infrared features resulting from the presence of pure glycerol, in b
acteria, were still existent for up to 2 or 3 hours after thawing proc
ess. The deconvoluted Amide I and Amide II bands of bacterial proteins
reflected important changes in secondary structure after treatment of
bacteria with dimethyl sulfoxide ( increase in P-sheet and loss of ra
ndom coil content). In contrast to glycerol, the cryoprotective action
of dimethyl sulfoxide probably involves interactions with a wide rang
e of intrabacterial species. (C) 1996 John Wiley & Sons, Inc.