Search

A new species ofHyphomicrobium is described. The organism was isolated from a sample of stored seawater originating from the harbor of Barcelona, Spain. The life cycles and various morphological types are illustrated by photomicrographs. Growth takes place readily on simple peptone media with the addition of a small amount of calcium or magnesium salt, or seawater. The general physiological and cultural characteristics are recorded.

The genetic relatedness of a number of budding and prosthecate bacteria was determined by deoxyribonucleic acid (DNA) homology experiments of the direct binding type. Strains of Hyphomicrobium sp. isolated from aquatic habitats were found to have relatedness values ranging from 9 to 70% with strain “EA-617,” a subculture of the Hyphomicrobium isolated by Mevius from river water. Strains obtained from soil enrichments had lower values with EA-617, ranging from 3 to 5%. Very little or no homology was detected between the amino acid-utilizing strain Hyphomicrobium neptunium and other Hyphomicrobium strains, although significant homology was observed with the two Hyphomonas strains examined. No homology could be detected between prosthecate bacteria of the genera Rhodomicrobium, Prosthecomicrobium, Ancalomicrobium , or Caulobacter , and Hyphomicrobium strain EA-617 or H. neptunium LE-670. The grouping of Hyphomicrobium strains by their relatedness values agrees well with a grouping according to the base composition of their DNA species. It is concluded that bacteria possessing cellular extensions represent a widely diverse group of organisms.

Chemical analysis of cell walls obtained from Hyphomicrobium B-522 and from a morphologically and nutritionally distinct organism, Hyphomicrobium neptunium (ATCC 15444), showed that the organisms have a similar cell wall composition, which is typical of gram-negative bacteria. The walls of both strains contained many amino acids, including the characteristic mucopeptide components diaminopimelic acid and muramic acid. Isolation of the mucopeptide by use of sodium dodecyl sulfate was successful only with cell walls of H. neptunium , thus revealing a difference between the walls of the two strains. The mucopeptide preparation contained glucosamine, muramic acid, alanine, glutamic acid, diaminopimelic acid, and glycine in molar ratios of 1.05:1.21:1.84:1.0:1.04:0.31, respectively. The concentration of glycine was sufficiently high to suggest that it is a mucopeptide component rather than an impurity.

Slide cultures ofHyphomicrobium T37 were observed microscopically. The organism behaved as classicalHyphomicrobium by budding from a polar hypha, and asPedomicrobium when irregular colonies were produced by three processes: production of several hyphae from the cell, branching of hyphae, and sessile budding. The criteria for delimiting the genusPedomicrobium are discussed in the light of these facts.

Vaccenic acid (11-18:1) accounted for 92% of the fatty acids in the extractable lipids of log-phase Nitrobacter and Hyphomicrobium . During the stationary phase, both genera formed a 19-carbon cyclopropane fatty acid which increased in proportion to a decrease in the amount of vaccenic acid.

Budding bacteria from aquatic or terrestrial habitats were found to accumulate ferric oxide hydrate (“ferric hydroxide”) on their cell surfaces. Metal paper clips served as the source of oxidizable iron. Pure cultures deposited ferric hydroxide during growth on sea water medium at a pH of 7.8, but not in a mineral salts medium of normal ionic strength, of pH 7.2, and without NaCl, although some active strains came from fresh water or soil.

Conti, S. F. (Dartmouth Medical School, Hanover, N.H.), and Peter Hirsch. Biology of budding bacteria. III. Fine structure of Rhodomicrobium and Hyphomicrobium spp. J. Bacteriol. 89:503–512. 1965.—The ultrastructure of 14 strains of hyphomicrobia, and of Rhodomicrobium vannielii, was investigated by means of electron microscopy of thin sections. The majority of the strains of hyphomicrobia possessed a well-developed internal membrane system, which appeared to be derived by invagination from the cytoplasmic membrane. The subcellular organization of the hyphomicrobia and R. vannielii was investigated.

Summary: Methyl mercaptan (MM)-oxidase was purified to near homogeneity from Thiobacillus thioparus TK-m grown on dimethyl sulphide. The enzyme was a monomer with an M r value of approximately 40000. It oxidized MM stoichiometrically to formaldehyde, S2- and H2O2. The enzyme had a K m of 31·3 μM for MM. It was also shown to oxidize ethyl mercaptan. MM-oxidase from T. thioparus was shown to have some different characteristics from MM-oxidase of Hyphomicrobium EG, such as a higher K m, the absence of inhibition by S2- and the inability to catalyse the oxidation of S2-.

Water, sediment, and wooden pilings, samples of which were collected from a harbor in Puerto Rico during the course of a long-term study of biofouling of wood treated with creosote and related compounds, were found to support growth of microbial populations, the dominant taxa of which included Hyphomicrobium, Hyphomonas, Pseudomonas, Vibrio, and Bacillus. New wood exposed to the harbor water was rapidly colonized by Hyphomicrobium vulgare. Old pilings in an advanced stage of biodeterioration maintained a diverse bacterial microflora, representatives of which were also found widely distributed in the water column and sediment. Evidence for bacterial species succession was obtained, indicating that microbial interactions are important for attachment to, and subsequent colonization of, wood surfaces in the marine environment.

Bacteria belonging to the order Hyphomicrobiales comprised less than 0.01% of the planktonic bacterial community of water samples collected from the Chesapeake Bay and surrounding tributaries. These budding bacteria, however, were present in all of the 15 samples assayed. Two strains of Hyphomicrobia were isolated, one from the mouth of the Patuxent River and another from a Rock Creek tributary (Hyphomicrobium RC).