Multivariate Analysis of Quantitative Chemical and Enzymic Characterization Data in Classification of Actinobacillus, Haemophilus and Pasteurella spp.

Abstract

Chemotaxondc data for strains of Actinobacilfus, Haemophilus and Pasteurella spp. were analysed using three multivariate statistical strategies; principal components, partial least squares discriminant, and soft independent modelling of class analogy. The species comprised Actinobacillus acti'nomycetemcomitans, Hemophilus aphrophilus, H. puraphrophilus, H. iduenzae, Pasteurella multocidrr, P. haemolytica and P. ureae. Strains were characterized by cell sugar and fatty acid composition, lysis kinetics during EDTA and EDTA plus lysozyme treatment, and methylene blue reduction. In total 23 quantitative variables were compiled from chemotaxonomic analyses of 25 strains. A. acthomycetemcomitans and H. aphrophilus formed distinct classes which Mered from those of H. paraphrophifus, H. inpUenzae and Pastewella spp. All characterization variables, except those describing fatty acid content, contributed significantly to inter-species discrimination.

Haemophilus influenzae Rd Lacks a Stringently Conserved Fatty Acid Biosynthetic Enzyme and Thermal Control of Membrane Lipid Composition

“…None of the genomic sequences available for this group of organisms contains a cfa gene homologue, and our lipid analyses (Fig. 2) as well as those available in the literature (3)(4)(5)(6)42) show that no cyclopropane fatty acids are present. The synthesis of cyclopropane fatty acids is thought to protect cells from environmental stresses and has been shown to allow E. coli to better survive shifts to low-pH environments (10).…”

“…The loss of this regulatory mechanism seems likely to be due to the lack of environmental selection, since H. influenzae exists in nature only in extremely close association with warm-blooded animals. This loss also seems likely to be the case in the other species of the family Pasteurellacae, since sequences encoding FabB but not FabF are found in these genomes and the sole unsaturated fatty acid reported in these cells is palmitoleic acid (3)(4)(5)(6)42). Indeed, species within the Pasteurellaceae cannot be distinguished by their fatty acid compositions (6).…”

“…This loss also seems likely to be the case in the other species of the family Pasteurellacae, since sequences encoding FabB but not FabF are found in these genomes and the sole unsaturated fatty acid reported in these cells is palmitoleic acid (3)(4)(5)(6)42). Indeed, species within the Pasteurellaceae cannot be distinguished by their fatty acid compositions (6). Except for fabF, the genes required for fatty acid synthesis in E. coli are completely conserved in the completed genomes available for Pasteurellaceae (H. influenzae Rd and P. multocida PM70).…”

“…An independent means to confirm that the fatty acids observed were the products of de novo synthesis rather than incorporation from the medium was provided by biosynthetic incorporation of a radioactive precursor into lipids. H. influenzae was grown on the lipid-extracted BHI medium supplemented with [1][2][3][4][5][6][7][8][9][10][11][12][13][14] C]acetate. The lipids were extracted, and the fatty acid moieties were then converted to their methyl esters.…”

Rapid identification of Actinobacillus actinomycetemcomitans based on analysis of 23S ribosomal RNA

“…The presumptive identification of A. actinotvvcetemcotnitatis from TSBV (25) selective medium is based on characteristic colony morphology, including a central star-like structure as well as a positive catalase test (25). Definitive speciation of A. acti-nomycetemcomitans isolates is based on additional biochemical tests, including fermentation of specific sugars (1,2,26). In addition to bacterial culture, other more rapid tests have been developed for the identification of ^.…”