Sporolactobacillus
Sporolactobacillus is a genus of bacteria. The type species is Sporolactobacillus inulinus, first described by Kitahara and Suzuki in 1963, expanded by Kitahara and Lai 1967. Types of Sporolactobacillus are spore-forming lactic acid bacteria.
- 4.1 Literature
- 4.2 Notes and references
Features
Appearance
The cells of the types of Sporolactobacillus are gram positive. Are straight rods with a diameter of 0.4 to 1.0 microns and a length of 2.0 to 4.0 microns. They occur singly, in pairs or rarely in chains. The species are mostly mobile ( motile ). The movement is done with the help of peritrichous flagella. Sporolactobacillus forms endospores as Überdauerungsform. The endospores are ellipsoidal with a diameter of 0.9-1.4 microns and a length of 1.0 to 2.1 microns. They are terminal or subterminal formed in the mother cell, it swells it to.
On solid media, the cells grow to gray to white, very small colonies. They are round in plan view, seen from the side convex and shiny. If the soil contains calcium carbonate, this is resolved by the formation of lactic acid, so that the colonies a clear yard can be seen.
Growth and metabolism
All kinds of Sporolactobacillus are heterotrophic, they do not perform photosynthesis. The representatives of the genus are facultative anaerobic or microaerophilic, ie growth occurs under complete exclusion of oxygen or under low oxygen content. The enzyme catalase is absent. You can utilize various carbohydrates in a fermentation to produce energy.
As the lactic acid bacteria produces lactic acid in a fermentation Sporolactobacillus which is therefore referred to as lactic acid fermentation. A distinction is made between homofermentative and heterofermentative species. The representatives of Sporolactobacillus are homofermentative, they produce from glucose almost exclusively lactic acid. The type strain of Sporolactobacillus inulinus this is predominantly ( > 99%) of D- (-)- lactic acid ( syn: (R) -lactic acid ), which is also referred to as levorotatory lactic acid. In other species has also a mixture of D - and L- found ( ) -lactic acid, (-) -.
Sporolactobacillus culturing is carried out in or on a culture medium which are suitable for lactic acid bacteria, for example, on MRS agar, a nutrient medium, which allows growth demanding lactic acid bacteria, as it contains complex growth factors. What growth factors Sporolactobacillus actually required is not yet known for most species. The culture medium is usually incubated at 30-37 ° C, this is recommended, a gas atmosphere containing 5% carbon dioxide, since, under normal air occurs only a very slow proliferation. Most tested strains to grow at temperatures between 20 and 40 ° C, the multiplication is optimal at about 30 ° C. Sporolactobacillus as produced lactic acid, it is able to grow even at low pH values. S. inulinus a pH of 3.2-3.8 in the medium was measured, in other species, a pH of 4.4.
Sporulation is not automatic, but is triggered by certain environmental influences on the cells. A nutrient medium, the components of which promote the formation of spores, has been described. It contains, inter alia, tomato juice, which is often used as a component of culture media for lactic acid bacteria, ammonium sulfate, and starch. The endospores are resistant to heat, they withstand heating to 70-80 ° C for 10 minutes and then can still germinate, but by heating to 90 ° C for 10 minutes, they are inactivated. As is common in bacterial endospores, they contain dipicolinic acid.
Occurrence and ecology
The bacteria according to the type described, was isolated from chicken feed. Almost all other hitherto discovered species were found in the rhizosphere and other soil samples. The locations are mainly in Japan and Southeast Asia. In the United States, two strains have been isolated, although 700 samples were tested for, is assumed that that is not frequently used, Sporolactobacillus.
Some species are mesophilic, ie they prefer moderate temperatures for growth. So shows Sporolactobacillus lactosus growth at 45 ° C, and many strains grow at 15 ° C.
System
The type species was first described in 1963 by Sporolactobacillus inulinus Kitahara and Suzuki. They discovered in chicken feed, a bacterium that represents an intermediate form of the genera Lactobacillus (because of the lactic acid fermentation) and Clostridium (due to the formation of spores ) in their view. They proposed a new subgenus ( subgenus, abbreviated as subgen. ) Sporolactobacillus before in the family Lactobacillaceae. The type species was described by them as Sporolactobacillus ( Subgen. Lactobacillus ) inulinus, with the result that the genus Lactobacillus was demoted to the rank of subgenus. It is likely that the correct name should be Lactobacillus ( Subgen. Sporolactobacillus ) inulinus. Later, the kind of Kitahara was, inter alia, referred to only as inulinus Sporolactobacillus and thus established Sporolactobacillus as a species.
In 1972, the genus was then placed to the family Bacillaceae. Only in 2010 was, inter alia, a new family Sporolactobacillaceae established by Ludwig, whose type genus is Sporolactobacillus. The Sporolactobacillaceae family is set to the order Bacillales, not to the order Lactobacillales, in many lactic acid bacteria are included. Both systems belong to the Firmicutes division.
The genus name refers to the presence of lactic acid bacteria (Latin lactis, " milk " ), the appearance of the cells (Latin bacillus, " small stick " ), and the ability to form spores (Greek spora, " Spore "). Sporolactobacillus is thus a rod-shaped bacterium in the milk, is capable of forming spores. In fact Sporolactobacillus is not found in milk, which is part of the genus name only refers to the similarity to the genus Lactobacillus, but does not form spores.
The following species of the genus are known (as of 2014):
- Sporolactobacillus inulinus ( Kitahara and Suzuki 1963) Kitahara and Lai 1967
- Sporolactobacillus kofuensis Yanagida et al. 1997
- Sporolactobacillus lactosus Yanagida et al. 1997
- Sporolactobacillus laevolacticus ( Andersch et al., 1994) Hatayama et al. 2006
- Sporolactobacillus nakayamae Yanagida et al. 1997 Sporolactobacillus nakayamae subsp. nakayamae Yanagida et al. 1997
- Sporolactobacillus nakayamae subsp. racemicus Yanagida et al. 1997