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M Doudoroff

Publications and source records attributed to M Doudoroff.

At least 19 recordsLinked to original sources
PubMed1980

Evolution in Pseudomonas fluorescens.

The relationships among 93 strains of Pseudomonas fluorescens were investigated by (1) a numerical taxonomic analysis on the results of 150 phenotypic tests, (2) DNA hybridization studies using 16 reference strains, (3) quantitative microcomplement fixation studies using six reference strains with antibodies directed against the protein azurin. In general, the strains fell into distinct clusters. Assignment to these clusters on the basis of azurin immunological similarity showed 98% agreement with assignment based on DNA homology, suggesting that many genes will follow the same pattern. Of the strains that clustered on the basis of genotype (DNA, azurin) 88% also clustered on the basis of phenotype. The occasional noncongruency observed between the genotypic and phenotypic data may be due to the variable rates of phenotypic evolution. These results provide a perspective on the roles of horizontal and vertical transfer of genes in the evolution of this bacterial group.

Azurin↗
PubMed1975

Lactate dehydrogenases in cyanobacteria.

NAD-linked lactate dehydrogenases specific for the D- and L-lactate have been demonstrated in a number of strains of unicellular cyanobacteria. The D-lactate dehydrogenase of one strain (Synechococcus 6716) was partially purified and its properties were studied. The enzyme has a molecular weight of ca. 115000-120000, is highly specific, autooxidizable, and susceptible to inhibition by iodoacetamide, oxamate and ATP. The possible physiological functions of the enzyme in the metabolism of the organism were investigated. D-lactate carbon was incorporated in cell material during photosynthetic growth with CO2, but lactate was not used as sole source for carbon for photosynthetic or chemosynthetic development. D-lactate and pyruvate were oxidized aerobically in the dark by resting cell suspensions with the assimilation mainly of the C2 and the C3 carbon atoms. In the oxidation of lactate, acetate was excreted into the medium. No fermentation of glucose was found, but a small amount of D-lactate was detected as a product of endogenous dark metabolism of the cell. All enzymes required for the production of lactate from glucose and from glycogen were found in exponentially growing cells, but the activity of some key enzymes was low or undetectable in old cultures.

Acetates↗
PubMed1972

Deoxyribonucleic acid homologies of some so-called "Hydrogenomonas" species.

Evidence based on deoxyribonucleic acid homology supports the abandonment of the genus Hydrogenomonas. Pseudomonas facilis (formerly Hydrogenomonas facilis) is closely related to the nonautotrophic species P. delafieldii. P. facilis and Alcaligenes eutrophus (often called H. eutropha) are not related to each other or to other hydrogen bacteria and pseudomonads studied.

Alcaligenes↗
PubMed1972

Deoxyribonucleic acid homologies among some Pseudomonas species.

Phylogenetic relationships among a number of strains belonging to the genus Pseudomonas were explored by the use of in vitro deoxyribonucleic acid (DNA) hybridization. The fluorescent nomenspecies (P. fluorescens, P. putida, P. aeruginosa, P. cichorii, P. syringae, and related species), as well as the nonfluorescent species P. stutzeri, P. mendocina, P. alcaligenes, and P. pseudoalcaligenes, were shown to belong to a single DNA homology complex which is isolated from other Pseudomonas species that have been studied [P. cepacia (= P. multivorans), P. caryophylli, P. marginata (= P. alliicola), P. pseudomallei, P. acidovorans, P. testosteroni, P. solanacearum, P. diminuta, P. facilis, P. delafieldii, P. saccharophila, P. palleronii]. A limited numerical analysis of the phenotypic properties of the examined strains supported, with some exceptions, their previous allocation to nomenspecies and biotypes. The internal structure and nomenclature of the "P. fluorescens homology complex" are discussed.

Biological Evolution↗
PubMed1971

Phenotypic characterization and deoxyribonucleic acid homologies of Pseudomonas solanacearum.

Twenty-six strains and colony variants of Pseudomonas solanacearum belonging to four described biotypes were characterized, by using 169 phenotypic characters previously found useful in distinguishing among strains of other Pseudomonas species. Deoxyribonucleic acid (DNA) hybridization (intra- and interspecific DNA-DNA hybridizations) was performed by using the in vitro "DNA competition" technique. P. solanacearum appears to be a moderately homogeneous species, which is, at most, only remotely related to all other species of the genus studied to date. The four biotypes are not clearly distinct from one another with respect to nutritional characters or DNA homologies. Discrepancies between acid production and growth with some carbohydrates were noted. Difficulties were encountered in certain DNA competition experiments and some problems of the methodology are discussed.

Bacteriological Techniques↗
PubMed1968

Study of the Moraxella group. I. Genus Moraxella and the Neisseria catarrhalis group.

A number of strains of oxidase-positive moraxellas and of neisserias related to Neisseria catarrhalis were characterized with respect to a number of nutritional and physiological properties and could be assigned to several species or species groups on the basis of their phenotypic traits. This grouping was consistent with that established by Bövre on the basis of transformation frequencies for streptomycin resistance. It is proposed to reserve the generic name Moraxella for the oxidase-positive rodshaped organisms, and a redescription of the genus is offered. Following the recent taxonomic proposals of Bövre and Henriksen, the specific name Moraxella osloensis is applied to the nutritionally unexacting strains that accumulate poly-beta-hydroxybutyrate as carbon reserve. The nutritionally exacting strains are assigned to three distinct groups which can be regarded as separate species or as varieties of M. lacunata. The epithets applicable to these groups appear to be lacunata, nonliquefaciens, and bovis. The "false neisserias" could be assigned to at least three subgroups, one of which constitutes the clearly defined entity, N. catarrhalis, which could be distinguished from N. caviae and N. ovis.

Microscopy, Phase-Contrast↗
PubMed1968

A study of the Moraxella group. II. Oxidative-negative species (genus Acinetobacter).

A number of nutritional and biochemical properties of more than 100 strains of the oxidase-negative moraxellas (the Mima-Herellea-Acinetobacter group of bacteria) were studied. These properties included the range of carbon sources that can support growth, the utilization of nitrate, the production of proteolytic and lipolytic enzymes, and the reactions involved in the oxidation of sugars and of aromatic compounds. No evidence could be obtained for the accumulation of either poly-beta-hydroxybutyrate or polysaccharide as intracellular reserve materials. Of 158 different compounds tested, the group as a whole could use 85 as sole carbon sources for growth. The nutritional spectra of the individual strains, however, differed widely, with a range of from 17 to 74 alternative substrates. On the basis of 56 selected nutritional and physiological characters used for a numerical analysis, the collection could be divided into two major groups of strains comprising at least seven less clearly defined clusters. Neither the hydrolysis of gelatin nor acid production from aldose sugars was found to be a reliable index of strain affinities indicated by the phenotypic analysis, although both properties were of some use in distinguishing between the subgroups. For reasons that are discussed, we propose that the oxidase-negative moraxellas be placed in the genus Acinetobacter Brisou and Prévot, for which a modified description is presented. A. calco-aceticus (Beijerinck) is proposed as the type species, of which anitratum is regarded as a synonym or variety. On the basis of the present studies and unpublished supporting evidence provided by M. Mandel on deoxyribonucleic acid (DNA) composition and by J. Johnson on DNA homologies, it is proposed that two other species in the genus, A. lwoffi (Audureau) and A. hemolysans (Henriksen), as well as one subspecies, A. hemolysans haemolyticus (Stenzel and Mannheim), be recognized provisionally.

Acinetobacter↗
PubMed1965

Decomposition of poly-beta-hydroxybutyrate by pseudomonads.

Delafield, F. P. (University of California, Berkeley), M. Doudoroff, N. J. Palleroni, C. J. Lusty, and R. Contopoulos. Decomposition of poly-beta-hydroxybutyrate by pseudomonads. J. Bacteriol. 90:1455-1466. 1965.-A number of aerobic pseudomonads capable of using poly-beta-hydroxybutyrate as sole source of carbon have been partially characterized. One was selected for special study and described as a new species, Pseudomonas lemoignei Delafield. This bacterium constitutively produces extracellular digestive enzymes that hydrolyze the polymer to a mixture of d-beta-hydroxybutyrate and the dimeric ester of this acid, as well as an intracellular "dimer hydrolase" which hydrolyzes the dimeric ester. The exoenzymes are excreted during growth, but mainly at its cessation. Metabolism of beta-hydroxybutyrate largely suppresses enzyme excretion and causes a disappearance of excreted enzyme.

Hydroxybutyrates↗