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- Computer-aided comparison of protein electrophoretic patterns for grouping and identification of heterotrophic bacteria from mineral waterPublication . Ferreira, A.C.; Morais, Paula V; Alcobia Gomes, Célia Margarida; Da Costa, MiltonThe microflora of a natural mineral water was studied immediately after bottling (T0) and after 7 d storage (T7) during 6 months, and isolates were clustered by SDS-PAGE of whole-cell protein profiles. Isolates from each cluster were further characterized by API 20NE, fatty acid composition and quinone profiles. The numerical analysis of the electrophoregrams of all bacteria isolated from the mineral water formed 15 clusters and five unclustered strains. Except for five minor clusters, all clusters were composed of strains isolated over several months. The numerical analysis of the electrophoregrams of bacteria isolated immediately after bottling formed 15 clusters while after 7 d storage only four of these populations could be isolated, indicating that populations present in the mineral water were stable and that changes occurring after bottling probably resulted from a selection process. Only one unclustered strain was identified simultaneously by all the systems, as Sphingomonas paucimobilis. The monitoring of the aquifer and the bottling system, and the construction of a large database with bacteria of the autochthonous flora allows the detection of alterations in the aquifer by changes in the microflora.
- Characterization of Legionella species by numerical analysis of whole-cell protein electrophoresisPublication . Veríssimo, António; Morais, Paula V.; Diogo, Alexandra; Alcobia Gomes, Célia Margarida; Costa, Milton S. daThe results of a computer-assisted whole-cell protein sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis of 291 isolates and 74 reference strains belonging to all known species of the genus Legionella revealed that the majority of the species of this genus can be adequately identified by this method. The type strain of Legionella bozemanii did not cluster with the other strains of this species, and the only strain of Legionella geestiana available clustered with the strains of Legionella feeleii. When we performed a numerical analysis by omitting certain portions of the pattern containing dense bands, all of the species could be distinguished. Our results also show that the type strains of Legionella nautarum and Legionella londiniensis deposited in the National Collection of Type Cultures do not correspond to the type strains deposited in the American Type Culture Collection. We used the results of a fatty acid and ubiquinone composition analysis to complement the SDS-PAGE results for several strains whose identities as determined by indirect immunofluorescence were doubtful. Computer-assisted SDS-PAGE of whole-cell proteins can be used in the classification of Legionella species and to identify and screen large numbers of isolates for further, in-depth taxonomic studies of smaller numbers of strains.