FT‐IR spectroscopic studies on molecular interactions of cryoprotectant agents with bacteria

Abstract

SYNOPSISFourier transform infrared spectroscopy was used to investigate, without any destructive interference, interactions of the cryoprotective agents, glycerol and dimethyl sulfoxide with Brudyrhizobium juponicum. The intracellular spectrum of glycerol, obtained by subtracting the spectrum of control bacteria from that of glycerol-treated bacteria, showed no differences in infrared features compared to that of pure glycerol. 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 and dimethyl sulfoxide uptake required only a few minutes. Moreover, the infrared features resulting from the presence of pure glycerol, in bacteria, were still existent for up to 2 or 3 hours after thawing process. The deconvoluted Amide I and Amide I1 bands of bacterial proteins reflected important changes in secondary structure after treatment of bacteria with dimethyl sulfoxide (increase in &sheet and loss of random coil content). In contrast to glycerol, the cryoprotective action of dimethyl sulfoxide probably involves interactions with a wide range of intrabacterial species.

ATR‐FTIR spectroscopic investigation of E. coli transconjugants β‐lactams‐resistance phenotype

“…This hypothesis seems more plausible to explain the differences in the ultrastructural and conformational status between the susceptible strain and the transconjugants bacterial cell wall polysaccharides. Moreover, amino‐sugar of peptidoglycan and phospholipids (cell wall components) absorb strongly in the carbohydrate region (1200–950 cm −1 ) [15]. However, the variation in the conformational status of these macromolecules can be observed at the spectral level [9].…”

“…Changes in the conformation status of both amino sugar of the peptidoglycan and phospholipids have direct repercussion in this region (1300–1200 cm −1 ). This is felt by a lower absorption intensity in this region [15]. Besides, complicated coupled modes of vibration that involves CH 2 OH groups of polysaccharides are observed in this region [14].…”

Cell surface groups of two picocyanobacteria strains studied by zeta potential investigations, potentiometric titration, and infrared spectroscopy

“…FTIR spectra contain prominent features derived from carbohy- Table 4 List of band assignments Wavenumber (cm −1 ) Assignment Comments ∼ 1740 v>C=O of ester functional groups primarily from membrane lipids and fatty acids [46] ∼ 1650 vC=O of amides associated with proteins [47,48] Usually called the amide I band ∼ 1540 δN-H of amides associated with proteins [47,48] Usually called the amide II band, may also contain contributions from C=N stretches ∼ 1455 δ ac CH 2 /δ ac CH 3 of proteins [49] The positions of these broad peaks vary in the literature, called the amine III band ∼ 1398 δ ac CH 2 /δ ac CH 3 and v s C-O of carboxylic groups [47,49] The positions of these assignments vary in the literature [20], specific features occur between 1500 and 1200 cm −1 . FTIR spectroscopy of freeze-dried cells was found to be a sensitive tool for the study of microbial cell surfaces [44].…”

Influence of H+ and Calcium Ions on Surface Functional Groups of Synechococcus PCC 7942 Cells

“…CH3 scissoring, δacCH2/δacCH3 of the positions of these broad proteins 55 peaks vary in the literature, called the amine III band ∼1398 δ acCH2/δacCH3 and νsCOOof carboxylic the positions of these groups 53,55 assignments vary in the literature ∼1240 ν asPdO of the phosphodiester backbone general phosphoryl groups of nucleic acid (DNA and RNA) and COOH ∼1200-900 νC-O-C of polysaccharides 55,56 , ∼1165, the predominant ∼1110, 1050, 1030 for C-O, polysaccharide in -P(OH)2, ∼1085, stretching of PdO in cyanobacteria is glycogen phosphate ∼1211 ∼ 1080 νsPdO of the phosphodiester backbone may also be due to the of nucleic acid (DNA and RNA) 53,56 presence of phosphorylated proteins and polyphosphate storage products ∼950-1150 asymmetric and symmetric stretching of PO 2and P(OH)2 in phosphate; vibrations of C-OH and C-C bonds in polysaccharides and alcohols. Approximate band positions are indicated in the figure.…”