Morganellaceae

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Morganellaceae
Morganella morganii (secondary electron microscope image)

Morganella morganii (secondary electron microscope image)

Systematics
Domain : Bacteria (bacteria)
Department : Proteobacteria
Class : Gammaproteobacteria
Order : Enterobacteria (Enterobacterales)
Family : Morganellaceae
Scientific name
Morganellaceae
Adeolu et al. 2016

The Morganellaceae are a family of Gram-negative bacteria . According to the phylogenetic system , they belong to the order of Enterobacterales in the class of Gammaproteobacteria in the division ( Divisio , also called Phylum among the prokaryotes ) Proteobacteria . The name of the family is derived from the type genus Morganella .

Until 2016, the representatives of the Morganellaceae of the Enterobacteriaceae family were assigned to the order "Enterobacteriales", but the name of this order was not valid according to the rules of the bacteriological code (ICBN). In 2016, phylogenetic methods led to the establishment of the order Enterobacterales (Enterobacteria), combined with a division of the previously known taxa into several new families. The Morganellaceae family includes eight genera (as of 2019), many of which are part of the healthy intestinal flora of humans and animals.

features

The establishment of the order Enterobacterales Adeolu et al. 2016 led to a division of the previously known taxa into several new families. This means that statements about Enterobacteriaceae or Enterobacteria in the literature before this point in time can at least partially be transferred to members of the Morganellaceae family. Further specific features are in the first description by Adeolu et al. contain.

Appearance

The cells are rod-shaped , no endospores are formed. Most members of the family can actively move with flagella , they are motile , but there are also genera that cannot move actively, e.g. B. Arsenophonus and Moellerella . Since the cell wall consists of a few murein layers and a second, outer membrane of phospholipids and lipopolysaccharides , the Morganellaceae are gram-negative .

Growth and metabolism

Cosenzaea myxofaciens in SIM agar with a positive result for H 2 S formation, with a negative result for the indole test and with a positive result for motility

Their metabolism is facultatively anaerobic , so they can break down substances through oxidation in the presence of oxygen and ferment under anoxic conditions (no oxygen) . The oxidase test is negative for Morganellaceae . You do not use the 2,3-butanediol fermentation , consequently the Voges-Proskauer test for the detection of the intermediate product acetoin in the 2,3-butanediol fermentation is negative. Another feature of the family is that the representatives do not contain the enzyme arginine dihydrolase (ADH). Additional biochemical properties that are used in diagnostic tests to differentiate the Morganellaceae genera can be found in the Evidence section . Typical for the representatives of the genus Proteus is a clear swarming behavior on moist culture media .

Phylogenetics

→ See also: Section Systematics and Taxonomy in the article of the order Enterobacterales

By using phylogenetic methods, the tribal history and the relationships between the bacteria can be clarified. In the description of the order Enterobacterales Adeolu et al. 2016 and the families belonging to it, the Morganellaceae form a monophyletic group in a phylogenetic tree (based on genome and genetic analyzes ) . Furthermore, seven conserved characteristic indels (Engl. ' Conserved signature inserts and deletions CSI) set, which are typical of the representatives of the family, but do not occur in the other bacteria of the order.

proof

Biochemical features, such as the enzymes present and the resulting metabolic properties, can be used in a colored row to differentiate between the individual genera and species of the Morganellaceae and thus to identify them. It is also possible to distinguish it from other representatives of enterobacteria. The individual representatives of the family differ in whether they are hydrogen sulfide (H 2 S) form, the hydrolysis of gelatin perform citrate (with Simmons citrate agar ) can utilize, via the enzyme urease have to urea to degrade or the Have the enzyme β-galactosidase , with which the disaccharide lactose (milk sugar) is hydrolytically split into the monosaccharides glucose and galactose in order to use them in the metabolism. The utilization of other carbohydrates is usually checked in diagnostic tests.

The genera Proteus , Providencia and Morganella are similar in their metabolic properties. All three genera produce phenylalanine deaminase , but no arginine dihydrolase (ADH), cannot metabolize malonate and do not form acid during dulcitol , D - sorbitol and L - arabinose metabolism. A systematic overview from the year 2000 of representatives of the three genera can be found in the section Biochemical Evidence in the article on the genus Proteus .

These examinations can be used for miniaturized test systems . Typical results for the representatives of the Morganellaceae can be viewed in the freely accessible database BacDive of the DSMZ ( German Collection of Microorganisms and Cell Cultures ), e.g. B. for Proteus vulgaris .

Systematics and taxonomy

External system

The Enterobacterales order established in 2016 includes eight families (including the Budviciaceae , Enterobacteriaceae and Hafniaceae ) with a total of around 60 genera. The type genus of the order that has been newly established and thus corresponds to the rules of the bacteriological code (ICBN) is the genus Enterobacter .

Internal system

Colonies of Morganella morganii on blood agar
Swarms of Proteus on blood agar
Secondary electron microscope image of Providencia alcalifaciens

Already in the 1960s, the close relationship of the genera Proteus , Morganella and Providencia known at the time was shown on the basis of phenotypic characteristics. They were listed in the Proteeae tribe . The known species were initially assigned to the genus Proteus , from which the other two genera were established by reclassifying individual species. In the case of genera described later, which were placed in the Enterobacteriaceae family as the only family in the order "Enterobacteriales", the similarity to Proteus was occasionally emphasized. The position in a common family is a logical consequence that has been proven by phylogenetic methods. In the description of the order Enterobacterales, the monophyletic group is referred to in the cladogram as Proteus - Xenorhabdus clade and as family Morganellaceae fam. nov. Are defined.

The type genus of the Morganellaceae family Adeolu et al. 2016 is the genus Morganella , the family includes the following genera (as of 2019):

Synonyms

The classification in the tribe Proteeae in the 1960s shows the initial difficulty of assigning certain taxa to a genus with certainty. Accordingly, there are numerous synonyms for certain types and genera of bacteria in the Morganellaceae family. In Morganella morganii ( Winslow et al. 1919) Fulton 1943 and Proteus morganii ( Winslow et al. 1919) Yale 1939, in Providencia rettgeri ( Hadley et al. 1918) Brenner et al. 1978 and Proteus rettgeri ( Hadley et al. 1918) Rustigian and Stuart 1943 as well as Providencia alcalifaciens ( de Salles Gomes 1944) Ewing 1962 and Proteus inconstans ( Ornstein 1920) Shaw and Clarke 1955 are both homotypical synonyms , since both species have the have the same type trunk.

Proteus myxofaciens was named Cosenzaea myxofaciens ( Cosenza and Podgwaite 1966) Giammanco et al. Reclassified in 2011 and thus established the Cosenzaea order at the same time . Similarly, Xenorhabdus luminescens was named Photorhabdus luminescens ( Thomas and Poinar 1979) Boemare et al. Placed in the new genus Photorhabdus in 1993 .

Occurrence

Many species of the Morganellaceae are part of the healthy intestinal flora of humans and animals. Unlike some other representatives of enterobacteria such as Salmonella , they are not regarded as necessarily pathogenic (disease-causing), even if they have been detected in medical samples (e.g. feces ), they are more likely to be opportunistic pathogens . Morganellaceae can also be found on or in insects , in particular representatives of the genera Arsenophonus , Xenorhabdus and Photorhabdus , which are considered to be pathogenic for special insect species.

meaning

Ecological importance

Photorhabdus luminescens was isolated from nematodes with which the bacterium forms a symbiosis , representatives of the genera Xenorhabdus and Photorhabdus are referred to as 'entomopathogenic nematophilic bacteria', i.e. bacteria that “like” (symbiotically) to live in nematodes, which in turn colonize insects as parasites and damage them. The nematodes are members of the Steinernematidae and Heterorhabditidae families . The nematodes with their bacterial symbionts are used for biological pest control .

Medical importance

Some representatives of the Morganellaceae occur as pathogens of nosocomial infections ("hospital germs") and infect people with weak immune systems . In particular Proteus mirabilis , Proteus penneri and Morganella morganii are clinically important as causative agents of, for example, bacteremia and meningoencephalitis in premature infants.

Proteus mirabilis and P. penneri are more often isolated from the faeces of patients with diarrhea without being the actual cause of the disease. On the other hand, urinary tract infections can be caused by P. penneri or Providencia stuartii , for example, as these bacteria have the enzyme urease and can utilize urea. The infections often occur when using urinary catheters .

swell

literature

Individual evidence

  1. ↑ a b c d e M. Adeolu, S. Alnajar, S. Naushad, RS Gupta: Genome-based phylogeny and taxonomy of the 'Enterobacteriales': proposal for Enterobacterales ord. nov. divided into the families Enterobacteriaceae, Erwiniaceae fam. nov., Pectobacteriaceae fam. nov., Yersiniaceae fam. nov., Hafniaceae fam. nov., Morganellaceae fam. nov., and Budviciaceae fam. nov. In: International Journal of Systematic and Evolutionary Microbiology. No. 66 , December 2016, p. 5575-5599 , doi : 10.1099 / ijsem.0.001485 .
  2. ↑ a b c d W. H. Ewing: The tribe Proteeae: Its Nomenclature And Taxonomy . In: International Bulletin of Bacteriological Nomenclature and Taxonomy . tape 12 , no. 3 , July 1962, p. 93-102 , doi : 10.1099 / 0096266X-12-3-93 .
  3. ↑ a b c R. L. Gherna, JH Werren, W. Weisburg, R. Cote, CR Woese, L. Mandelco, DJ Brenner: NOTES: Arsenophonus nasoniae gen. Nov., Sp. nov., the Causative Agent of the Son-Killer Trait in the Parasitic Wasp Nasonia vitripennis . In: International Journal of Systematic Bacteriology . tape 41 , no. October 4 , 1991, doi : 10.1099 / 00207713-41-4-563 .
  4. ^ A b F. W. Hickman-Brenner, GP Huntley-Carter, Y. Saitoh, AG Steigerwalt, JJ Farmer, DJ Brenner: Moellerella wisconsensis, a new genus and species of Enterobacteriaceae found in human stool specimens. In: Journal of clinical microbiology. Volume 19, Number 4, April 1984, pp. 460-463, PMID 6715516 , PMC 271095 (free full text).
  5. ↑ a b c d e f g C. M. O'Hara, FW Brenner, JM Miller: Classification, identification, and clinical significance of Proteus, Providencia, and Morganella. In: Clinical Microbiology Reviews. Volume 13, number 4, October 2000, pp. 534-546, doi : 10.1128 / cmr.13.4.534-546.2000 , PMID 11023955 , PMC 88947 (free full text) (review).
  6. ^ German collection of microorganisms and cell cultures (DSMZ): Proteus vulgaris, Type Strain. In: Website BacDive . Retrieved December 23, 2019 .
  7. ↑ a b Jean Euzéby, Aidan C. Parte: Classification of domains and phyla - Hierarchical classification of prokaryotes (bacteria). In: List of Prokaryotic names with Standing in Nomenclature, Systematics of Bacteria (LPSN) . Retrieved December 23, 2019 .
  8. ^ Jean Euzéby, Aidan C. Parte: Familiy Morganellaceae. In: List of Prokaryotic names with Standing in Nomenclature, Systematics of Bacteria (LPSN) . Retrieved December 23, 2019 .
  9. ^ Taxonomy Browser Morganellaceae. In: National Center for Biotechnology Information (NCBI) website . Retrieved December 23, 2019 .
  10. ^ A b Jean Euzéby, Aidan C. Parte: Genus Proteus. In: List of Prokaryotic names with Standing in Nomenclature, Systematics of Bacteria (LPSN) . Retrieved December 23, 2019 .
  11. ↑ a b N. E. Boemare, RJ Akhurst, RG Mourant: DNA Relatedness between Xenorhabdus spp. (Enterobacteriaceae), Symbiotic Bacteria of Entomopathogenic Nematodes, and a Proposal To Transfer Xenorhabdus luminescens to a New Genus, Photorhabdus gen. Nov. In: International Journal of Systematic Bacteriology . tape 43 , no. 2 , April 1993, p. 249-255 , doi : 10.1099 / 00207713-43-2-249 .

Web links

Commons : Morganellaceae  - collection of images, videos, and audio files
 Wikispecies: Morganellaceae  - Species Directory