''Debaryomyces hansenii'' is a species of

yeast Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are estimated to constit ...

in the family

Saccharomycetaceae The Saccharomycetaceae are a family of yeasts in the order Saccharomycetales that reproduce by budding. Species in the family have a cosmopolitan distribution, and are present in a wide variety of habitats, especially those with a plentiful supp ...

. Also known as ''Candida famata'', it accounts for up to 2% of invasive

candidiasis Candidiasis is a fungal infection due to any type of '' Candida'' (a type of yeast). When it affects the mouth, in some countries it is commonly called thrush. Signs and symptoms include white patches on the tongue or other areas of the mouth ...

cases.

Ecology

''Debaryomyces hansenii'' is an osmo-, halo- and xerotolerant

that produces toxins, including mycocins, to destroy competitive yeast species. It is a common species in all types of cheese, including soft cheeses and the brines of semi-hard and hard cheeses, and the most common yeast among 383 isolates from samples of unsulphited or sulphited sausages, skinless sausages and minced beef. It contributes to the fermentation of barrel-aged beers such as Le Coq Imperial Stout from

Harveys Brewery Harvey's Brewery is a brewery in Lewes, East Sussex, England. Harvey's estate includes 45 tied houses, mostly in Sussex, and three in London: Royal Oak, Southwark, The Cat's Back, Wandsworth and The Phoenix, Stockwell. It sells and distri ...

in southern England. Harvey's head brewer speculates that it is either airborne in the brewery or a slow-growing component of their house yeast blend. ''D. hansenii'' is also found in hyper-saline waters such as the

saltern A saltern is an area or installation for making salt. Salterns include modern salt-making works (saltworks), as well as hypersaline waters that usually contain high concentrations of halophilic microorganisms, primarily haloarchaea but also othe ...

s on the Atlantic coast of

Namibia Namibia (, ), officially the Republic of Namibia, is a country in Southern Africa. Its western border is the Atlantic Ocean. It shares land borders with Zambia and Angola to the north, Botswana to the east and South Africa to the south and ea ...

or in the Great Salt Lake of

Utah Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to it ...

Nutritional requirements

The species can be cultivated in media with up to 25%

NaCl Sodium chloride , commonly known as salt (although sea salt also contains other chemical salts), is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chloride ions. With molar masses of 22.99 and 35.45 g/ ...

or 18%

glycerol Glycerol (), also called glycerine in British English and glycerin in American English, is a simple triol compound. It is a colorless, odorless, viscous liquid that is sweet-tasting and non-toxic. The glycerol backbone is found in lipids known ...

. Growth rate increases in solutions with ≥ 1 M NaCl or

KCl Potassium chloride (KCl, or potassium salt) is a metal halide Salt (chemistry), salt composed of potassium and chlorine. It is odorless and has a white or colorless vitreous lustre, vitreous crystal appearance. The solid dissolves readily in wa ...

, with sodium and potassium ions playing a very important role in the mechanisms involved in maintaining osmobalance. The species can survive a pH range between 3 and 10. Furthermore, ''D. hansenii'' has been described as the species with the highest

perchlorate A perchlorate is a chemical compound containing the perchlorate ion, . The majority of perchlorates are commercially produced salts. They are mainly used as oxidizers for pyrotechnic devices and to control static electricity in food packaging. Per ...

tolerance reported to date, which might have consequences for the microbial habitability of

Mars Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury. In the English language, Mars is named for the Roman god of war. Mars is a terrestrial planet with a thin at ...

, where perchlorate salts are widely distributed.

Reproduction

Most strains are haploid, mating very rarely and diploidize transiently by somatogamous

autogamy Autogamy, or self-fertilization, refers to the fusion of two gametes that come from one individual. Autogamy is predominantly observed in the form of self-pollination, a reproductive mechanism employed by many flowering plants. However, species o ...

(i.e. fusion of two cells but excluding their nuclei). Sexual reproduction proceeds via heterogamous conjugation (i.e. the conjugation of two cells of different form or size) leading to short diplophase followed by

meiosis Meiosis (; , since it is a reductional division) is a special type of cell division of germ cells in sexually-reproducing organisms that produces the gametes, such as sperm or egg cells. It involves two rounds of division that ultimately r ...

and

ascospore An ascus (; ) is the sexual spore-bearing cell produced in ascomycete fungi. Each ascus usually contains eight ascospores (or octad), produced by meiosis followed, in most species, by a mitotic cell division. However, asci in some genera or ...

formation. Haploid yeasts reproduce

vegetatively Vegetative reproduction (also known as vegetative propagation, vegetative multiplication or cloning) is any form of asexual reproduction occurring in plants in which a new plant grows from a fragment or cutting of the parent plant or spec ...

by multilateral budding.

Genetics

This species has seven chromosomes, labeled A-G. This species uses an alternative genetic code for the codon CUG, coding for the amino acid serine instead of the usual leucine.

Differentiation

The ability of this species to grow at 10% NaCl or 5% glucose is used to discriminate ''D. hansenii'' from other ascomycetous yeasts. The species comprises two

varieties Variety may refer to: Arts and entertainment Entertainment formats * Variety (radio) * Variety show, in theater and television Films * ''Variety'' (1925 film), a German silent film directed by Ewald Andre Dupont * ''Variety'' (1935 film), ...

: ''D. hansenii'' var. ''hansenii'' and var. ''fabryii''. These two groups can be differentiated via

rRNA Ribosomal ribonucleic acid (rRNA) is a type of non-coding RNA which is the primary component of ribosomes, essential to all cells. rRNA is a ribozyme which carries out protein synthesis in ribosomes. Ribosomal RNA is transcribed from ribosoma ...

, the

electrophoretic mobility Electrophoresis, from Ancient Greek ἤλεκτρον (ḗlektron, "amber") and φόρησις (phórēsis, "the act of bearing"), is the motion of dispersed particles relative to a fluid under the influence of a spatially uniform electric fi ...

of their

glucose-6-phosphate dehydrogenase Glucose-6-phosphate dehydrogenase (G6PD or G6PDH) () is a cytosolic enzyme that catalyzes the chemical reaction : D-glucose 6-phosphate + NADP+ + H2O 6-phospho-D-glucono-1,5-lactone + NADPH + H+ This enzyme participates in the pentose phospha ...

, or by their maximum grow temperatures (35 °C for var. ''hansenii'' and 39 °C for var. ''fabryii'').

Biotechnology

The species has been demonstrated to synthesize useful quantities of D-arabinitol, riboflavin,

xylitol Xylitol is a chemical compound with the formula , or HO(CH2)(CHOH)3(CH2)OH; specifically, one particular stereoisomer with that structural formula. It is a colorless or white crystalline solid that is freely soluble in water. It can be classifi ...

, and pyruvic acid under thiamine limitation. The species has also been used to decarboxylate

Ferulic acid Ferulic acid is a hydroxycinnamic acid, an organic compound with the formula (CH3O)HOC6H3CH=CHCO2H. The name is derived from the genus ''Ferula'', referring to the giant fennel ('' Ferula communis''). Classified as a phenolic phytochemical, ferul ...

to 2-Methoxy-4-vinylphenol via

biotransformation Biotransformation is the biochemical modification of one chemical compound or a mixture of chemical compounds. Biotransformations can be conducted with whole cells, their lysates, or purified enzymes. Increasingly, biotransformations are effected w ...

(a 95.07% yield, 1470.8 mg/L, within 10 hours).

References

External links

* {{Taxonbar, from=Q10467497 Fungi described in 1889 Yeasts Osmophiles Halophiles Xerophiles Saccharomycetaceae Taxa named by Friedrich Wilhelm Zopf