| Alicyclobacillus | |
|---|---|
Scientific classification  | |
| Domain: | Bacteria |
| Phylum: | Bacillota |
| Class: | Bacilli |
| Order: | Bacillales |
| Family: | Alicyclobacillaceae |
| Genus: | Alicyclobacillus Wisotzkey 1992 |
| Type species | |
| Alicyclobacillus acidocaldarius (Darland & Brock 1971) Wisotzkey 1992 [1] | |
| Species | |
See text | |
Alicyclobacillus is a genus of Gram-variable, rod-shaped, spore-forming bacteria. The bacteria are able to grow in acidic conditions, while the spores are able to survive typical pasteurization procedures.
Alicyclobacilli are strictly aerobic, acidophilic, mesophilic to thermophilic, soil-dwelling organisms. [2] Alicyclobacilli are of special interest to the fruit juice canning industry because common pasteurization techniques (92 °C for 10 seconds) do not deactivate the spores; [3] Alicyclobacillus species can have a D95-value of over 8 minutes (requiring treatment of over 8 minutes at 95 °C to kill 90% of spores). [4] When a product is spoiled by Alicyclobacillus, the juice products develop a disinfectant-like odor and/or flavor (due to guaiacol production), but the bacteria do not cause swelling of the package or discoloration of the product, [4] nor is it pathogenic to humans. [5] Alicyclobacilli have been implicated in spoilages of pear, orange, peach, mango, and white grape juice, fruit juice blends, and tomato products. [6] Not all Alicyclobacilli produce guaiacol, and thus not all species are of spoilage concern. [7] A. consociatus and A. pohliae were originally classified in genus Alicyclobacillus, but were later reclassified into the novel genus Effusibacillus in 2014. [8]
Most Alicyclobacillus species optimally grow in the 40-55 °C range. [9] The exceptions include A. acidocaldarius (65 °C), [9] A. aeris (30 °C), [10] A. disulfidooxidans (35 °C), [11] [12] and A. ferrooxydans (28 °C). [13] A. acidocaldarius is the most thermotolerant, as is able to grow in temperatures up to 70 °C. [9] A. disulfidooxidans is the only psychrotroph, being able to grow at 4 °C. [11] [12] Most species can grow in the pH 2.0-6.0 range, and none have been shown to grow above pH 6.5. [9] A. disulfidooxidans is the most acid-tolerant, and can grow at pH 0.5. [11] [12]
The first Alicyclobacillus species was isolated in 1967 from hot springs, and was named Bacillus acidocaldarius. However, it was not until 1982 that the organisms were implicated in the spoilage of apple juice. The next outbreak occurred in 1994, and based on 16S rRNA studies, a separate genus was proposed. [4] The genus name derives from ω-alicyclic fatty acids as the major component in the cellular membrane, and to reflect the previous classification as Bacillus . [9] A. acidoterrestris is considered the most important spoilage species within the genus Alicyclobacillus, [14] but A. acidocaldarius,A. pomorum, and A. herbarius have also been isolated from spoiled product. [15] Soil is a common habitat for species of Alicyclobacillus, and is likely the source for contamination of food products. [9]
The canning industry works under the assumption that bacterial spores will not germinate at pH values below 4.6, and that acid-tolerant organisms are not very heat resistant. In this case, a low heat pasteurization process is applicable. However, the emergence of Alicyclobacillus as a spoilage organism has led some researchers to advocate using A. acidoterrestris as the reference organism to design pasteurization processes for high acid foods, just as the thermal death time of Clostridium botulinum was used to design the sterilization process for low acid canned foods. [16] High-pressure processing has been shown to be effective at inactivating A. acidoterrestris spores in orange juice. [17] One survey of 8556 samples of fruit and vegetable juices found Alicyclobacillus in 13% of samples, [18] while another study found Alicyclobacillus in 6% out of 180 samples, [19] and another found the bacteria in 14% out of 75 samples. [4]
In The Netherlands in 2013, contamination of raspberry with Alicyclobacillus in pasteurized juices led to a public recall after consumers complained about bad taste and odor. [20]
| 16S rRNA based LTP_08_2023 [21] [22] [23] | 120 marker proteins based GTDB 08-RS214 [24] [25] [26] | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Sulfur-reducing bacteria are microorganisms able to reduce elemental sulfur (S0) to hydrogen sulfide (H2S). These microbes use inorganic sulfur compounds as electron acceptors to sustain several activities such as respiration, conserving energy and growth, in absence of oxygen. The final product of these processes, sulfide, has a considerable influence on the chemistry of the environment and, in addition, is used as electron donor for a large variety of microbial metabolisms. Several types of bacteria and many non-methanogenic archaea can reduce sulfur. Microbial sulfur reduction was already shown in early studies, which highlighted the first proof of S0 reduction in a vibrioid bacterium from mud, with sulfur as electron acceptor and H
2 as electron donor. The first pure cultured species of sulfur-reducing bacteria, Desulfuromonas acetoxidans, was discovered in 1976 and described by Pfennig Norbert and Biebel Hanno as an anaerobic sulfur-reducing and acetate-oxidizing bacterium, not able to reduce sulfate. Only few taxa are true sulfur-reducing bacteria, using sulfur reduction as the only or main catabolic reaction. Normally, they couple this reaction with the oxidation of acetate, succinate or other organic compounds. In general, sulfate-reducing bacteria are able to use both sulfate and elemental sulfur as electron acceptors. Thanks to its abundancy and thermodynamic stability, sulfate is the most studied electron acceptor for anaerobic respiration that involves sulfur compounds. Elemental sulfur, however, is very abundant and important, especially in deep-sea hydrothermal vents, hot springs and other extreme environments, making its isolation more difficult. Some bacteria – such as Proteus, Campylobacter, Pseudomonas and Salmonella – have the ability to reduce sulfur, but can also use oxygen and other terminal electron acceptors.
The Alicyclobacillaceae are a family of Gram-positive bacteria. All members of this family are aerobic and form endospores.
Acidophiles or acidophilic organisms are those that thrive under highly acidic conditions. These organisms can be found in different branches of the tree of life, including Archaea, Bacteria, and Eukarya.
Alicyclobacillus aeris is a species of Gram positive/Gram variable, strictly aerobic, bacterium. The bacteria are acidophilic and produced endospores. It was first isolated from a copper mine in Inner Mongolia, China. The species was first described in 2009, and the name is derived from the Latin aeris.
Alicyclobacillus fastidiosus is a species of Gram positive, strictly aerobic, bacterium. The bacteria are acidophilic and produce endospores. It was first isolated from apple juice. The species was first described in 2007, and the name refers to the fastidious nature of the organism; the bacteria would start to die off after 7 days when plated on typical agar for isolating Alicyclobacillus. Additionally, the species produced fewer spores than other members of its genus, and took much longer to produce the spores.
Alicyclobacillus kakegawensis is a species of Gram positive, strictly aerobic, bacterium. The bacteria are acidophilic and produce endospores. It was first isolated from soil in Kakegawa, Japan. The species was first described in 2007, and the named after the city from which it was first isolated.
Alicyclobacillus macrosporangiidus is a species of Gram positive, strictly aerobic, bacterium. The bacteria are acidophilic and produce endospores. It was first isolated from soil in a crop field in Fujieda, Japan. The species was first described in 2007, and the name is derived from the Latin macros (big) and sporangium (sporangia), referring to the large spores produced by the organism.
Alicyclobacillus sacchari is a species of Gram positive, strictly aerobic, bacterium. The bacteria are acidophilic and produce endospores. It was first isolated from liquid sugar. The species was first described in 2007, and the name is derived from the Latin sacchari.
Alicyclobacillus cycloheptanicus is a species of Gram positive, strictly aerobic, bacterium. The bacteria are acidophilic and produce endospores. It was first isolated from soil. The species was originally classified as Bacillus cycloheptanicus in 1987, but further 16S rRNA studies found that the species belonged in the newly created genus Alicyclobacillus. The species name refers ω-cycloheptane fatty acids in the cell membrane.
Alicyclobacillus acidocaldarius is a species of Gram positive, strictly aerobic, bacterium. The bacteria are acidophilic, thermophilic, and produce endospores. The first identified strains of A. acidocaldarius were from geysers in Yellowstone National Park and fumerole soil in Hawaii Volcano National Park. The species was originally classified as Bacillus acidocaldarius in 1971, but further 16S rRNA studies found that the species belonged in the newly created genus Alicyclobacillus. The species name is derived from the Latin acidum (acid) and caldarius, referring to the acidic and high temperature environments from which it was first isolated. Thomas D. Brock was one of the researchers who first categorized the species; his discovery of Thermus aquaticus allowed for other researchers to discover Taq polymerase and polyermase chain reaction (PCR).
Alicyclobacillus tolerans is a species of Gram positive, strictly aerobic, bacterium. The bacteria are acidophilic and produced endospores. It was first isolated from oxidizable lead–zinc ores in Uzbekistan. The strain was first identified in 1983, but was classified as Sulfobacillus thermosulfidooxidans subsp. thermotolerans strain K1. It was reclassified as Alicyclobacillus in 2005. The species name refers to the ability to tolerate changes in temperature and pH.
Alicyclobacillus ferrooxydans is a species of Gram positive, strictly aerobic, bacterium. The bacteria are acidophilic and produce endospores. It was first isolated from solfataric soil. The species was first described in 2008, and the name refers to its ability to oxidize iron.
Effusibacillus is a genus of Gram-positive, rod-shaped, aerobic, spore-forming bacteria.
Effusibacillus consociatus is a species of Gram positive, aerobic, bacterium. The cells are rod-shaped and form spores. It was first isolated from a blood sample from a 51-year-old woman, although it was not implicated as a pathogen. The species name is derived from Latin consociatus, to indicate that the bacteria was associated with a human clinical case.
Effusibacillus lacus is a species of Gram positive, facultatively anaerobic, thermophilic bacterium. The cells are rod-shaped and form spores. It was first isolated from freshwater lake sediment from Lake Mizugaki, Japan. The species name is derived from lacus.
Effusibacillus pohliae is a species of Gram positive, aerobic, thermophilic bacterium. The cells are rod-shaped and form spores. It was first isolated from Mount Melbourne, Antarctica. The species is named after the genus of Pohlia nutans, a species of moss that was colonizing the area where the type strain was isolated. E. pohliae has also been isolated from a geothermal heat pump in South Korea.
Margalitia is a genus of gram-positive or gram-variable rod-shaped bacteria in the family Bacillaceae from the order Bacillales. The type species of this genus is Margalitia shackletonii.
Niallia is a genus of Gram-Positive rod-shaped bacteria in the family Bacillaceae from the order Bacillales. The type species of this genus is Niallia circulans.
Rossellomorea is a genus of Gram-Positive or Gram-variable staining rod-shaped bacteria in the family Bacillaceae from the order Bacillales. The type species of this genus is Rossellomorea aquimaris.
Weizmannia is a genus of Gram-Positive rod-shaped bacteria in the family Bacillaceae from the order Bacillales. The type species of this genus is Weizmannia coagulans.