Cell suspensions of the haloarchaea Halorubrum sodomense and Halobacterium salinarum and the extremely halophilic bacterium Salinibacter ruber (Bacteroidetes) in saturated solutions of chlorides and sulfates (NaCl, KCl, MgSO4·7H2O, K2SO4, and (NH4)Al(SO4)2·12H2O) were left to evaporate to produce micrometric inclusions in laboratory-grown crystals. Raman spectra of these pinkish inclusions were obtained using a handheld Raman spectrometer with green excitation (532 nm). This portable instrument does not include any microscopic tool. Acceptable Raman spectra of carotenoids were obtained in the range of 200-4000 cm-1. This detection achievement was related to the mode of illumination and collection of scattered light as well as due to resonance Raman enhancement of carotenoid signals under green excitation. The position of diagnostic Raman carotenoid bands corresponds well to those specific carotenoids produced by a given halophile. To our best knowledge, this is the first study of carotenoids included in the laboratory in crystalline chlorides and sulfates, using a miniature portable Raman spectrometer. Graphical abstract ᅟ.
- Keywords
- Carotenoids, Halophilic prokaryotes, Inclusions, Miniature Raman spectrometer, Salts,
- MeSH
- Bacteroidetes chemistry MeSH
- Potassium Chloride chemistry MeSH
- Sodium Chloride chemistry MeSH
- Halobacterium salinarum chemistry MeSH
- Halorubrum chemistry MeSH
- Carotenoids analysis MeSH
- Limit of Detection MeSH
- Spectrum Analysis, Raman instrumentation MeSH
- Sulfates chemistry MeSH
- Publication type
- Journal Article MeSH
- Names of Substances
- Potassium Chloride MeSH
- Sodium Chloride MeSH
- Carotenoids MeSH
- Sulfates MeSH
Laboratory cultures of a number of red extremely halophilic Archaea (Halobacterium salinarum strains NRC-1 and R1, Halorubrum sodomense, Haloarcula valismortis) and of Salinibacter ruber, a red extremely halophilic member of the Bacteria, have been investigated by Raman spectroscopy using 514.5nm excitation to characterize their carotenoids. The 50-carbon carotenoid α-bacterioruberin was detected as the major carotenoid in all archaeal strains. Raman spectroscopy also detected bacterioruberin as the main pigment in a red pellet of cells collected from a saltern crystallizer pond. Salinibacter contains the C40-carotenoid acyl glycoside salinixanthin (all-E, 2'S)-2'-hydroxy-1'-[6-O-(methyltetradecanoyl)-β-d-glycopyranosyloxy]-3',4'-didehydro-1',2'-dihydro-β,ψ-carotene-4-one), for which the Raman bands assignments of are given here for the first time.
- MeSH
- Bacteroidetes chemistry MeSH
- Glycosides chemistry isolation & purification MeSH
- Haloarcula chemistry MeSH
- Halobacteriaceae chemistry MeSH
- Halobacterium salinarum chemistry MeSH
- Halorubrum chemistry MeSH
- Carotenoids chemistry isolation & purification MeSH
- Spectrum Analysis, Raman MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Names of Substances
- bacterioruberin MeSH Browser
- Glycosides MeSH
- Carotenoids MeSH
- salinixanthin MeSH Browser
The genome organization of the archaebacteria is investigated in three model systems: a) rRNA genes of various archaebacteria, b) a plasmid of 15.6 kb from Sulfolobus acidocaldarius which exists in free or integrated form, c) the 59 kb genome of phage phi H of Halobacterium halobium as a model for the unusual structural variability of DNA in this organism. Several variants of this phage have been isolated, their genomes differ by several insertions, a deletion, and an inversion. The frequent inversion and circularization of a 12 kb segment of DNA appears to be linked to the presence of two copies of an IS element at its flanks. DNA-dependent RNA polymerases have been isolated from a large number of archaebacteria including representatives of 4 families of the novel order Thermoproteales . As shown by immunological methods, they are closely related to those of eukaryotes. Two different types of RNA polymerase exist in the two main branches of the archaebacteria. The role of one component of the enzyme of Thermoplasma acidophilum was elucidated using an in vitro transcription system.
- MeSH
- Archaea genetics MeSH
- Bacteria genetics MeSH
- Genes, Bacterial * MeSH
- RNA, Bacterial genetics MeSH
- Bacteriophages genetics MeSH
- DNA, Bacterial metabolism MeSH
- DNA-Directed RNA Polymerases metabolism MeSH
- DNA, Viral MeSH
- Transcription, Genetic * MeSH
- Halobacterium genetics MeSH
- Plasmids MeSH
- RNA, Ribosomal genetics MeSH
- Genes, Viral MeSH
- Publication type
- Journal Article MeSH
- Names of Substances
- RNA, Bacterial MeSH
- DNA, Bacterial MeSH
- DNA-Directed RNA Polymerases MeSH
- DNA, Viral MeSH
- RNA, Ribosomal MeSH
