The genus Cryobacterium comes from the Greek words kryos meaning cold and bakterion. The type species is C. psychrophilum. Cryobacterium is a genus of bacteria of the phylum Actinobacteria, class Actinobacteria, order Micrococcales and family Microbacteriaceae.
Bacteria of this genus grow at a range or temperatures from −6 to 28°C. Most are psychrophilic and psychrotolerant meaning they prefer or are tolerant of cold temperatures. Other characteristics include, strictly aerobic, catalase-positive and oxidase-negative. The diagnostic cell-wall amino acid is L‐2,4‐Diaminobutyric acid. The main cellular fatty acids are iso- and anteiso-branched acids and MK-10 is the predominant menaquinone. Polar lipids of Cryobacterium contain diphosphatidylglycerol, phosphatidylglycerol and an unidentified glycolipid.
The genus Cryobacterium was first proposed in 1997 and the name Cryobacterium psychrophilum was suggested to replace Curtobacterium psychrophrophilum by Ken-Ichiro Suzuki at the Japan Collection of Microorganisms, The Institute of Physical and Chemical Research (RIKEN) in Wako-shi, Saitama, Japan and colleagues. The obligately psychrophilic (cold loving) bacteria was originally discovered from soil in Antarctica by Inoue and Komagata in 1976 who gave the name Curtobacterium psychrophrophilum. Based on unusual properties of the organism, Suzuki proposed C. psychrophilum JCM 1463T be classified under a new genus, Cryobacterium.
Cryobacterium species have been found which are psychrophilic, psychrotolerant, or mesophilic (prefer moderate temperatures). Psychrophilic microorganisms colonize permanently cold environments including deep sea, mountain and polar locations.
Cryobacterium aureum is psychrophilic, grow at 0-18 C and were isolated from glacier ice in China.
Cryobacterium flavum grow at 0-19 C and were isolated from glacier ice in China.
Cryobacterium levicorallinum is psychrophilic and isolated from glacier ice in China.
Cryobacterium luteum grows at 0-20 C and was isolated from glacier ice in China.
Cryobacterium mesophilum was collected from a soil sample in Bigeum Island, South Korea and grows optimally at 25-28 C.
Cryobacterium psychrophilum is the type species of the genus described above.
Cryobacterium psychrotolerans is psychrotolerant, able to grow 4–27 °C, optimal growth is at 20–22 °C, isolated from a glacier in China.
Cryobacterium roopkundense is psychrophilic, grows optimally between 15-18 C and was collected at the periphery of the glacial Lake, Roopkund, in the Himalayan mountain range, India.
Cryobacterium sp. MLB-32, isolated from cryoconite holes of glaciers in the high Arctic.
Cryobacterium spp. SO1 and SO2 were isolated from snow samples from the Fildes Peninsula, King George Island, Antarctica
Cryobacterium have been found to be a source of carotinoids for biotechnological production. In the pharmaceutical, cosmetic, food and feed industry these isoprenoid pigments could potentially be used as antioxidants and colorants.
Psychrophilic and psychrotropic bacteria are potential sources of cold-active enzymes and metabolites which may have industrial applications. Genome analysis of Cryobacterium strains SO1 and SO2 showed genes common in cold-adapted bacteria such as molecular chaperones, heat-shock proteins, cold-shock proteins, low-temperature requirement protein A and antifreeze proteins. Enzymes with biotechnological and industrial applications found in the genomes of these Cryobacteria strains include alkaline phosphatase, Uracil-DNA glycosylase, RNase polymerases and ligases for molecular biology. Genes coding for cold-active enzymes such as protease, lipase, amylase, chitinase, superoxide dismutase, beta-galactosidase and neopullulanase were also found.