Raman spectra of biological materials are very complex, because they consist of signals from all molecules present in cells. In order to obtain chemical information from these spectra, it is necessary to know the Raman patterns of the possible components of a cell. In this paper, we present a collection of Raman spectra of biomolecules that can serve as references for the interpretation of Raman spectra of biological materials. We included the most important components present in a cell: (1) DNA and RNA bases (adenine, cytosine, guanine, thymine and uracil), (2)

In this work, the possible contribution of Raman spectroscopy in forensic science is evaluated, more specifically for the analysis of automotive paint samples. Spectra from paint flakes as well as from cross sections were examined, in order to identify not only the pigments but also binders and extenders in all paint layers. Moreover, the possibility of distinguishing paint samples from different cars was evaluated to assess the use of vibrational spectroscopic techniques in the investigation of a hit-and-run accident.The presence of rutile and extenders, such as calcite and barium sulphate, could be demonstrated by their characteristic Raman bands. However, the identification of the binder by Raman spectroscopy was hampered: only with additional information from IR analysis could most of the bands in the spectrum be assigned to molecular vibrations of the binders. In contrast, organic pigments, having very distinctive and well-resolved characteristic bands, could easily be identified by comparing the spectra from the basecoat of the sample with spectra from a reference database. Because of these characteristic bands, the basecoat seems to provide the best spectra to distinguish paint samples. Moreover, some paints can also be distinguished by the absence or presence of the bands from calcium carbonate and barium sulphate in the primer surfacer. When recording spectra from paint flakes, Raman bands from the spectra of the clearcoat as well as from the basecoat are obtained.

Endospores and endospore-forming bacteria were studied by Raman spectroscopy. Raman spectra were recorded from Bacillus licheniformis LMG 7634 at different steps during growth and spore formation, and from spore suspensions obtained from diverse Bacillus and Paenibacillus strains cultured in different conditions (growth media, temperature, peroxide treatment). Raman bands of calcium dipicolinate and amino acids such as phenylalanine and tyrosine are more intense in the spectra of sporulating bacteria compared with those of bacteria from earlier phases of growth. Raman spectroscopy can thus be used to detect sporulation of cells by a characteristic band at 1,018 cm(-1) from calcium dipicolinate. The increase in amino acids could possibly be explained by the formation of small acid-soluble proteins that saturate the endospore DNA. Large variations in Raman spectra of endospore suspensions of different strains or different culturing conditions were observed. Next to calcium dipicolinate, tyrosine and phenylalanine, band differences at 527 and 638 cm(-1) were observed in the spectra of some of the B. sporothermodurans spore suspensions. These bands were assigned to the incorporation of cysteine residues in spore coat proteins. In conclusion, Raman spectroscopy is a fast technique to provide useful information about several spore components.

This study explored the potential of Raman spectroscopy for the analysis of poly(3-hydroxybutyrate) (PHB) in bacteria. PHB can be formed in large amounts by certain bacteria as a storage material and is of high importance for industrial biodegradable plastic production. Raman spectra were collected from Cupriavidus necator DSM 428 (H16), from its non-PHB-producing mutant strain C. necator DSM 541, and from pure PHB, in order to determine at which Raman shifts a contribution of PHB in bacterial spectra can be expected. The Raman band intensity at ca. 1734 cm-1 appeared to be suitable for the monitoring of PHB production and consumption. These intensities were linearly related to the PHB concentration (mg L-1 culture) determined by parallel HPLC analysis. Therefore, Raman spectroscopy is considered as a fast and noninvasive technique for the determination and monitoring of the PHB content in bacteria.

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In this study, the effect of low-shear microgravity on the metabolism of Cupriavidus metallidurans LMG 1195 was studied with Raman spectroscopy. Therefore, the strain was cultured for 24 or 48 h in a rotating wall vessel to simulate microgravity (SMG) and in a control setup. The differences in Raman spectra recorded from both setups after 24 h of culturing were small. The most prominent features in a difference spectrum, calculated between the mean spectra from the microgravity and the control setup separately, could be assigned to the presence of poly-β-hydroxybutyrate (PHB). SMG seems to yield a higher PHB production after 24 h of culturing. Additional processing of the spectra suggested that SMG induced also other changes in the carbon metabolism. After 48 h, similar results were found for the carbon metabolism, while PHB concentrations were reduced in SMG compared to the control. However, these differences could also be caused by interfering effects that may occur in the bioreactors after a prolonged incubation time.