High-performance liquid chromatographic analysis of ubiquinones from new Legionella species

A survey of the methods for the characterization of microbial consortia and communities

A survey of the available literature on methods most frequently used for the identification and characterization of microbial strains, communities, or consortia is presented. The advantages and disadvantages of the various methodologies were examined from several perspectives including technical, economic (time and cost), and regulatory. The methods fall into 3 broad categories: molecular biological, biochemical, and microbiological. Molecular biological methods comprise a broad range of techniques that are based on the analysis and differentiation of microbial DNA. This class of methods possesses several distinct advantages. Unlike most other commonly used methods, which require the production of secondary materials via the manipulation of microbial growth, molecular biological methods recover and test their source materials (DNA) directly from the microbial cells themselves, without the requirement for culturing. This eliminates both the time required for growth and the biases associated with cultured growth, which is unavoidably and artificially selective. The recovered nucleic acid can be cloned and sequenced directly or subpopulations can be specifically amplified using polymerase chain reaction (PCR), and subsequently cloned and sequenced. PCR technology, used extensively in forensic science, provides researchers with the unique ability to detect nucleic acids (DNA and RNA) in minute amounts, by amplifying a single target molecule by more than a million-fold. Molecular methods are highly sensitive and allow for a high degree of specificity, which, coupled with the ability to separate similar but distinct DNA molecules, means that a great deal of information can be gleaned from even very complex microbial communities. Biochemical methods are composed of a more varied set of methodologies. These techniques share a reliance on gas chromatography and mass spectrometry to separate and precisely identify a range of biomolecules, or else investigate biochemical properties of key cellular biomolecules. Like the molecular biological methods, some biochemical methods such as lipid analyses are also independent of cultured growth. However, many of these techniques are only capable of producing a profile that is characteristic of the microbial community as a whole, providing no information about individual members of the community. A subset of these methodologies are used to derive taxonomic information from a community sample; these rely on the identification of key subspecies of biomolecules that differ slightly but characteristically between species, genera, and higher biological groupings. However, when the consortium is already growing in chemically defined media (as is often the case with commercial products), the rapidity and relatively low costs of these procedures can mitigate concerns related to culturing biases. Microbiological methods are the most varied and the least useful for characterizing microbial consortia. These methods rely on traditional tools (cell counting, selective growth, and microscopic examination) to provide more general characteristics of the community as a whole, or else to narrow down and identify only a small subset of the members of that community. As with many of the biochemical methods, some of the microbiological methods can fairly rapidly and inexpensively create a community profile, which can be used to compare 2 or more entire consortia. However, for taxonomic identification of individual members, microbiological methods are useful only to screen for the presence of a few key predetermined species, whose preferred growth conditions and morphological characteristics are well defined and reproducible.Key words: microbial communities, microbial consortia, characterization methods, taxonomic identification.

Identification of clinical and environmental isolates of Legionella pneumophila by analysis of outer-membrane proteins, ubiquinones and fatty acids

47 strains of L. pneumophila, 9 reference strains of eight serogroups, 15 clinical isolates and 23 water-derived strains from different cities were analysed with respect to three chemical constituents of the cell envelope: outer- membrane proteins (OMPs), ubiquinones and fatty acids. The OMPs were obtained by Sarkosyl-extraction of a total membrane preparation and analysed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The ubiquinone content was quantitated by high-performance liquid chromatography (HPLC) and the fatty acid composition was established by gas-liquid chromatography coupled with mass spectrometry (GLC-MS). In all strains the OMP yielded the known characteristic pattern with the major component of 29 kilodalton. The ubiquinone content was very consistent within different strains revealing Q-12 with 65% as the predominant feature. Q-11 and Q-13 were present in amounts of 11% and 23%, respectively. Q-14 was found in trace amounts of about 0.65%. Only a very few ubiquinones with side chains shorter than 11 residues were present. GLC-MS allowed an unequivocal identification of each fatty acid. The branched chain fatty acid i-16:0 was the predominant feature with 33% followed by the unsaturated straight-chain acid 16:1. In this respect earlier reports by other authors were confirmed but minor compounds not detected so far could be revealed as 15:1, the doublet 18:1 and i-18:0, 19:1 and 20:1. OMP profiles are easy to establish and to interpret. They are well suited for identification of the species L. pneumophila. Ubiquinone analysis permits rapid but preliminary species identification, whereas fatty acid analysis by GLC-MS is an intricate technique providing a valuable chemical marker for L. pneumophila. The biochemical analyses presented here can supplement immunological studies, clarify immunological findings and help to identify new serogroups of L. pneumophila.

Isolation and characterization of a novel coenzyme Q from some methane-oxidizing bacteria

The respiratory quinone composition of 18 strains of obligate methane-utilizing bacteria was examined. All of the strains contained lipoquinones which on examination by tlc co-chromatographed with coenzyme Q. On the basis of chromatographic and physicochemical analyses the lipoquinones produced by 10 of the strains corresponded to Q-8. Reverse-phase partition and argentation hplc demonstrated the quinone produced by the remaining 8 strains did not correspond to any known coenzyme Q prenologue. On the basis of mass spectrometry, 1H and 13C nuclear magnetic resonance spectrometry the novel quinone was shown to correspond to 2,3-dimethoxy-5-methyl-6-(18-methylene-3,7, 11,15,19,23,27,31-octamethyldotriacontahepta-2,6,10,14,22,26,30 enyl-)-1, 4-benzoquinone.