Pedomicrobium

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Pedomicrobium
Systematics
Domain : Bacteria (bacteria)
Department : Proteobacteria
Class : Alphaproteobacteria
Order : Rhizobiales
Family : Hyphomicrobiaceae
Genre : Pedomicrobium
Scientific name
Pedomicrobium
TV Aristovskaya et al. 1961

Pedomicrobium is a genus of bacteria of the order of the Rhizobiales . The genus is one of the " budding bacteria ", there is no binary cell division , instead daughter cells are formed on hyphae .

Appearance

Pedomicrobium life cycle . 1. Mother cell with hyphae and buds, 2. Buds, 3. Swarmers, 4. Cell adhering to a solid surface, 5. Formation of hyphae, 6. Mother cell with hyphae and beginning bud formation

The cells of each species of Pedomicrobium are oval, spherical, or bean-shaped. Chopsticks also appear. Propagation takes place through budding. Daughter cells are formed on cytoplasmic outgrowths of the cell, so-called hyphae. Depending on the type, up to 5 hyphae are formed. The hyphae can also branch out. At least one origin of the hyphae is found on the side of the mother cell; others can also appear on the cell poles. The formation of new cells occurs through the formation of buds at the hyphae tips. The long axis of the new cells is perpendicular to the hyphal axis. The newly formed cells either remain associated with the hyphae or peel off as flagellated bacteria, they are then used as moth (English Swarmer cells hereinafter). These mobile cells can then attach themselves to the ground again and form new hyphae. The parent cells can also be connected to one another and thus form a network of connected cells.

The vertical positioning of the buds on the tips of the hyphae is a unique feature of the genus Pedomicrobium and can be used to distinguish this genus from other hyphae-forming bacteria, e.g. B. Hyphomicrobium , Hyphomonas , Hirschia , Dichotomicrobium and Rhodomicrobium .

Growth and metabolism

The species of Pedomicrobium are chemo-organotroph . Acetate is used as a carbon source , some strains can also use other compounds, such as pyruvate . The bacteria need oxygen ( aerobic ). The main quinone that occurs is ubiquinone-10 (Q-10). The GC content of the DNA is 63-67%.

All species show growth at temperatures between 20–30 ° C and at pH values between 7–9. The species P. ferrugineum grows at temperatures between 10–43 ° C, optimal growth occurs at temperatures between 29–30 ° C. P. americanum shows growth at temperatures of 15–41 ° C, the best temperatures are between 32–38 ° C. P. ferrugineum grows at pH values ​​between 3.5–10, the best pH value for growth is 9.

Pedomicrobium forms thick cell capsules through extracellular polymers .

The addition of vitamins in the colonies promotes growth; if there are no vitamins, pleomorphic cells form, which form granules of poly-β-hydroxybutyric acid . Most Pedomicrobium bacterial strains can use the amino acids glutamate , aspartate , glycine , serine , threonine and valine as organic sources of nitrogen . Some strains can also use inorganic nitrogen compounds, but growth is slow.

The individual cultures can be yellow or reddish brown to dark brown in color, which can be attributed to the oxidation of iron or manganese . It is assumed that the bacteria use the organic content of iron and manganese chelates, such as iron fulvate and humic acids that are formed in the soil. Iron and manganese are deposited as Fe (III) and Mn (IV) on the cell surface. One speaks of iron or manganese susceptible bacteria. No energy is gained here, as would be the case with iron or manganese breathing. So it is not about chemolithotrophic bacteria that oxidize iron or manganese to generate energy.

Systematics

The genus Pedomicrobium is a member of the Hyphomicrobiaceae family . They belong within the bacteria to the Proteobacteria department , there to the Alphaproteobacteria class (α group) and in the order Desulfuromonadales . The type species is Pedomicrobium ferrugineum , it was first described in 1961.

From australicum Pedomicrobium described by Rainer encoder and Marita Beese in 1988, no tribe is gone. It was therefore suggested that this species should no longer be included in the system.

In November 2019 the following species were listed:

  • Pedomicrobium americanum Gebers and Beese 1988
  • Pedomicrobium australicum Gebers and Beese 1988
  • Pedomicrobium ferrugineum Aristovskaya 1961
  • Pedomicrobium manganicum Aristovskaya 1961

ecology

The various finds come from a. from soils , eg Podsol -floor, fresh water , sea water and ferrous sources.

Pedomicrobium can also contribute to the formation of the so-called desert varnish . desert varnish or rock varnish . They are mostly shiny and reddish or graphite colored, thin deposits on the surfaces of rocks. The desert varnish is mostly formed in deserts, but also occurs in tropical and high mountains. It consists mainly of clay minerals with embedded iron and manganese oxides in the formation of which Pedomicrobium is involved.

Other bacteria, such as Metallogenium, can also be involved in the formation of iron and manganese oxides through oxidation. Purely physical and chemical processes can also lead to the formation of desert varnish .

Individual evidence

  1. ↑ a b c d e f g h i Eugene Rosenberg, Edward F. DeLong, Stephen Lory, Erko Stackebrandt and Fabiano Thompson: The Prokaryotes . Alphaproteobacteria and Betaproteobacteria ISBN 978-3-642-30197-1
  2. ↑ a b c Jiri Hausler: Freshwater flora of Central Europe, Vol. 20: Schizomycetes . Springer, 1982, ISBN 978-3-8274-2141-8 , pp. 421 .
  3. ↑ a b c George M. Garrity (Ed.): Bergey's Manual of Systematic Bacteriology . 2nd edition, Volume 2: The Proteobacteria. Part C: The Alpha-, Beta-, Delta-, and Epsilonproteabacteria . Springer, New York 2005, ISBN 0-387-24145-0 .
  4. ↑ Johannes CG Ottow: Microbiology of Soils: Biodiversity, Ecophysiology and Metagenomics . Springer, 2011. ISBN 9783642008238
  5. ^ Rainer Gebers and Marita Beese: Pedomicrobium americanum sp. nov. and Pedomicrobium australicum sp. nov. from Aquatic Habitats, Pedomicrobium gen. emend., and Pedomicrobium ferrugineum sp. emend In: International Journal of Systematic and Evolutionary Microbiology. (1988), Volume 38, Number 3.
  6. ↑ Jean Euzéby, Aidan C. Part: Pedomicrobium . In: List of Prokaryotic names with Standing in Nomenclature. Retrieved November 21, 2019 .
  7. ↑ a b RI Dorn and TM Oberlander: Microbial Origin of Desert Varnish. In: Science . Volume 213, Issue 4513 (September 11, 1981), pp. 1245-1247. doi : 10.1126 / science.213.4513.1245

literature

  • George M. Garrity: Bergey's manual of systematic bacteriology . 2nd Edition. Springer, New York, 2005, Vol. 2: The Proteobacteria Part C: The Alpha-, Beta-, Delta-, and Epsilonproteabacteria ISBN 0-387-24145-0
  • Eugene Rosenberg, Edward F. DeLong, Stephen Lory, Erko Stackebrandt and Fabiano Thompson: The Prokaryotes . Alphaproteobacteria and Betaproteobacteria Springer, Berlin, Heidelberg 2014, ISBN 978-3-642-30197-1

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