Erwinia
Erwinia is a genus of Gram-negative rod-shaped bacteria of the family Enterobacteriaceae ( Enterobacteriaceae ). They are facultatively aerobic, ie in the presence of oxygen ( oxic environment ) is their energy metabolism by oxidation, when there is no oxygen ( anoxic environment ), they change in energy metabolism to fermentation. Almost all species are peritrichous flagella, ie actively mobile. Many species of Erwinia ( and earlier Asked to this genus species) are plant pests.
In recent years, made some changes in the systematics of this group. Investigations showed to great differences in the DNA, so that many species were found to other genera ( Pantoea, Enterobacter, Pectobacterium and Brenneria ). Especially in the agricultural sciences (due to the role as plant pests) that the species to be addressed, however, led and still under the old name.
Metabolism
The members of the genus Erwinia are chemoorganotroph, they build for energy from various organic substances. They are facultatively aerobic, ie in the presence of oxygen have an oxidative energy metabolism, they oxidize the organic matter completely to carbon dioxide (CO2 ) and water. If there is no oxygen present, they switch to the 2.3 - Butandiolgärung. This arises from glucose as the end product, especially the alcohol 2,3- butanediol, together with small amounts of acids are formed. Further features of the 2,3- Butandiolgärung are intermediate acetoin and a particularly high gas production ( carbon dioxide CO2). The intermediate acetoin can be detected using the Voges - Proskauer reaction. More Butandiolgärer the enterobacteria are eg Enterobacter, Klebsiella and Serratia.
Other genera of enterobacteria use under anoxic conditions also a fermentation, but a different form, the mixed acid fermentation so-called (mixed acids fermentation). In the mixed acid fermentation occurs mainly acids such as acetic acid, lactic acid and succinic acid, but not butanediol as final products. The Mixed acid fermentation show, inter alia, the genera Escherichia, Salmonella, and Proteus. The various end products and gas developments of the two metabolic pathways are an important feature for distinguishing the genera.
Plant pathogens species
Many Erwinia species build plant remains from, but also in the development of plant diseases involved or are considered pests.
- So Erwinia carotovora triggers ( The system was changed, the correct name is now Pectobacterium carotovorum ) blackleg on potatoes. The bacterium damages the plant by the degradation of pectins by the enzyme pectinase. In pectins are intracellular Substancen in the middle lamella of the plant cells serve primarily the strength. By removing the affected plant tissue dissolves.
- Erwinia amylovora is the causative agent of fire blight. Affected are many kinds of rose plants (Rosaceae ), especially pome fruit crops.
- Erwinia billingia is another pest of various Rosaceae.
- Erwinia cypripedii ( correct name now Pectobacterium cypripedii ) damages various orchids such as Cypripedium.
Some species have been found in humans or animals, its role as a pathogen has not been established.
System
Currently ( 2007) the following types of Erwinia are known.
- Erwinia amylovora ( Burrill 1882) Winslow et al. 1920 ( Approved Lists 1980) emend. Hood et al. 1998 ( type species )
- Erwinia aphidicola Harada et al. 1998
- Erwinia billingiae Mergaert et al. 1999
- Erwinia carotovora, a synonym for Pectobacterium carotovorum
- Erwinia oleae Moretti et al. 2011
- Erwinia mallotivora Goto 1976
- Erwinia papayae Gardan et al. 2004
- Erwinia persicina Hao et al. 1990
- Erwinia piriflorinigrans López et al. 2011
- Erwinia psidii Rodrigues Neto et al. 1988
- Erwinia pyrifoliae Kim et al. 1999
- Erwinia rhapontici ( Millard 1924) Burkholder 1948
- Erwinia tasmaniensis Geider et al. 2006
- Erwinia toletana Rojas et al. 2004
- Erwinia tracheiphila (Smith 1895) Bergey et al. 1923
Some changes
Various Erwinia species were in the genus Pantoea, Enterobacter, Pectobacterium and Brenneria (all belong to the Enterobacteriaceae ) provided.
- To the newly created (1999 ) Genre Brenneria were among others the species Erwinia alni, Erwinia quercina, Erwinia rubrifaciens, Erwinia salicis and Erwinia paradisiaca (synonym: Dickeya paradisiaca ) provided.
- To Pantoea stewartii were the types Erwinia, Erwinia herbicola ( Enterobacter agglomerans synonym ), Erwinia milletiae transferred Erwinia uredovora (synonym Erwinia ananatis ).
- To the genus Enterobacter now include the species Erwinia cancerogena, Erwinia nimipressurali and Erwinia dissolvens (synonym: Enterobacter cloacae subsp dissolvens. ).
- Erwinia carotovora, Erwinia chrysanthemi and Erwinia cypripedii were asked to the genus Pectobacterium.