Hyphomicrobiaceae

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Hyphomicrobiaceae
Three cells from Hyphomicrobium sp.

Three cells from Hyphomicrobium sp.

Systematics
Classification : Creature
Domain : Bacteria (bacteria)
Department : Proteobacteria
Class : Alphaproteobacteria
Order : Rhizobiales
Family : Hyphomicrobiaceae
Scientific name
Hyphomicrobiaceae
B. Babudieri 1950

The Hyphomicrobiaceae are a family of bacteria . They belong to the Proteobacteria .

features

The family is very diverse in terms of the morphology and physiology of its members. The genus Aquabacter is rod-shaped, capsal and has gas vesicles . It is usually not flagellated; a single flagellum is only formed under certain conditions . The type strain of the species (as of February 2020), A. spiritensis , was isolated from Spirit Lake on Mount St. Helens , about a year after the 1980 eruption. Methylorhabdus is rod-shaped and not flagellated.

Many members belong to the prosthecate bacteria (compare the Caulobacteraceae family ), so they have cell appendages. These are called hyphae. " Budding bacteria " are also part of the family. There is no binary cell division here , instead daughter cells are formed on the hyphae . These include B. Pedomicrobium , Rhodomicorobium and Hyphomicrobium . The name of the genus and family refers to the hyphae.

The formation of endospores does not take place in the family.

metabolism

Most representatives are chemoorganoheterotrophh (compare metabolism and energy changes ) and rely on oxygen , i.e. aerobic . The genus Ancalomicrobium , which was formerly part of this family, can also grow in the absence of oxygen ( anaerobically ) and gains energy through denitrification or through mixed acid fermentation . Here, fermented it glucose to acetate , lactate , formate , succinate and H 2 and CO 2 .

Some species are also able to use organic compounds with only one carbon atom for energy production and as a carbon source for growth. One speaks of the facultative methylotrophic bacteria. These include B. Species of Hyphomicrobium , the species Methylorhabdus multivorans and Angulomicrobium tetraedrale . Hyphomicrobium uses u. a. Methanol , methylamine , formaldehyde and formate . Nitrate serves as an electron acceptor . A strain of Hyphomicrobium can also use dichloromethane as its sole source of carbon and energy.

Angulomicrobium shows growth with either methanol or formate as the only carbon source. It can also grow chemolithoautotrophically with CO 2 , H 2 and O 2 . A strain of Hyphomicrobium can also grow chemolithotrophically by using hydrogen as an electron donor . Some species, such Blastochloris i Rhodomicrobium and Rhodoplanes are under anaerobic conditions, so the absence of oxygen, facultative photoheterotroph , so can energy through photosynthesis win. They belong to the group of non-sulfur purple bacteria . But they also need organic nutrients and are therefore not autotrophic . When oxygen is present, cellular respiration occurs . However, species of blastochloris can also grow photoautotrophically . An isolate of Blastochloris sulfoviridis can use toluene as a carbon source in the light under anaerobic conditions .

Chemotaxonomic Features

cis -vaccenic acid

The most common fatty acids are C 18: 1 ω-7 c ( cis -Omega-7-octadecenoic acid or cis - vaccenoic acid ), 11-methyl-C 18: 1 ω-7 c and C 16: 0 ( hexadecanoic acid , palmitic acid) and C. 18: 0 ( octadecanoic acid , stearic acid). The most common ubiquinones are ubiquinone-10 or ubiquinone-9 and somewhat less often ubiquinone-11 . Menaquinones and rhodoquinones occur in the phototrophic species .

Systematics

The Hyphomicrobiaceae belong to the order of the Rhizobiales of the Alphaproteobacteria . On the basis of analyzes of 16S rRNA sequences, some taxonomic changes were made. Here are a few examples: Some species that originally belonged to the Hyphomicrobiaceae were transferred to other families. So was z. B. the species Hyphomicrobium neptunium of the genus Hyphomonas of the family of Hyphomonadaceae as Hyphomonas neptunium reassigned. The species Hyphomicrobium indicum was reclassified as Photobacterium indicum . This species is now one of the Vibrionaceae within the Gammaproteobacteria . Two species of Prosthecomicrobium were transferred to the newly created genus Bauldia , which as of December 2019 is not yet assigned to a specific family, but remains in the order Rhizobiales. Rhodopseudomonas rosea was identified as a type species of the new genus Rhodoplanes of the Hyphomicrobiaceae, as Rhodoplanes roseus comb. nov. reclassified. The species Rhodopseudomonas cryptolactis was also added to the genus and listed as Rhodoplanes cryptolactis , since 2017 it has been referred to as Rhodoplanes tepidamans . The former species Rhodopseudomonas viridis and rhodopseudomonas sulfoviridis were added to the newly established genus Blastochloris transferred and continue to be managed in the family Hyphomicrobiaceae.

The Hyphomicrobiaceae family comprises more than 20 genera (as of 2020), a list of some genera follows:

ecology

The species of the Hyphomicrobiaceae can be found in almost all habitats , for example in fresh and sea water, soils, brackish water and in waters with high salt values ​​(hypersalin). Thus, the types of Hyphomicrobium are widespread in soils and in aquatic habitats. Pedomicrobium was u. a. from floors , e.g. B. Podsol -floor, fresh water , sea water and ferruginous sources isolated. Seliberia was isolated from soil and fresh water.

Prosthecal bacteria such as Hyphomicrobium and Prosthecomicrobium have been found in fresh water, brackish and marine water, in groundwater and in the soil. The extensions of the cells (prosthecates) bring an advantage within oligotrophic (nutrient-poor) biotopes, since the surface of the cell is enlarged for the uptake of nutrients and thus the food shortage can be better compensated. So come Hyphomicrobium also found in laboratory water fountains, faucets or similar sources.

Dichloromethane

The strain Hyphomicrobium spec. DM2 can also use dichloromethane as the sole source of carbon and energy. Dichloromethane is a highly water-soluble halogenated compound that is highly toxic to most organisms, including humans. Under natural environmental conditions it occurs only in very small quantities, while it is used very often as a solvent in industry. As a result, the presence of dichloromethane in the environment has increased significantly since the 1960s. Bacteria that are able to break down dichloromethane are therefore of interest for the bioremediation of ecosystems.

The species Devosia neptuniae was isolated from the legume species water mimosa ( Neptunia natans ). This plant species occurs in subtropical and tropical waters. The bacterium has genes for nitrogen fixation and nodule formation (nodulation, compare nodule bacteria ). Devosia yakushimensis was isolated from kudzu root nodules ( Pueraria montana ), also one of the legumes. It was not yet clear until 2014 whether this could be a symbiosis.

Pedomicrobium is one of the bacteria susceptible to iron or manganese. It oxidizes iron and manganese and deposits the Fe (III) and Mn (IV) formed on the cell surface. It is believed that the bacteria thereby remove the organic content of iron and manganese chelates, such as. B. of iron fulvates and humic acids for your metabolism. The oxidation of iron and manganese is not used directly to generate energy, it is not a question of chemolithotrophic bacteria.

Individual evidence

  1. ↑ a b c d Jean Euzéby, Aidan C. Parte: Family Hyphomicrobiaceae. In: List of Prokaryotic names with Standing in Nomenclature (LPSN). Retrieved February 21, 2020 .
  2. ↑ a b c d e f g Eugene Rosenberg, Edward F. DeLong, Stephen Lory, Erko Stackebrandt and Fabiano Thompson: The Prokaryotes . Alphaproteobacteria and Betaproteobacteria ISBN 978-3-642-30197-1
  3. ^ Jean Euzéby, Aidan C. Parte: Species Rhodoplanes tepidamans. In: List of Prokaryotic names with Standing in Nomenclature (LPSN). Retrieved February 21, 2020 .
  4. ^ A. Semenov and JT Staley: Ecology of polyprosthecate bacteria . In: Advances in microbial ecology, vol 12. (1992) Plenum Publishing Company, New York, pp. 339-382
  5. ↑ Lexicon of Biology. Spectrum Academic Publishing House
  6. ↑ Emilie E. L. Muller, Françoise Bringel, Stéphane Vuilleumier: Dichloromethane-degrading bacteria in the genomic age . In: Research in Microbiology Volume 162, Issue 9, November 2011, pp. 869-876
  7. ↑ Johannes CG Ottow: Microbiology of Soils: Biodiversity, Ecophysiology and Metagenomics . Springer, 2011. ISBN 9783642008238

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