''Hanseniaspora occidentalis'' 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 constitut ...

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 suppl ...

. In its

anamorph In mycology, the terms teleomorph, anamorph, and holomorph apply to portions of the life cycles of fungi in the phyla Ascomycota and Basidiomycota: *Teleomorph: the sexual reproductive stage (morph), typically a fruiting body. *Anamorph: an ase ...

form, it was called ''Kloeckera javanica''. It has been isolated in the wild from soil samples and vineyards. Samples of a variant have been isolated from orange juice and rotten oranges. It has demonstrated potential as an organism to reduce

malic acid Malic acid is an organic compound with the molecular formula . It is a dicarboxylic acid that is made by all living organisms, contributes to the sour taste of fruits, and is used as a food additive. Malic acid has two stereoisomeric forms ...

in wine production.

Taxonomy

The yeast was originally isolated by Albert Klöcker in the

anamorphic Anamorphic format is the cinematography technique of shooting a widescreen picture on standard 35 mm film or other visual recording media with a non-widescreen native aspect ratio. It also refers to the projection format in which a distorted ...

form in 1912 and classified as ''Pseudosaccharomyces occidentalis''. Because the ''Pseudosaccharomyces'' name had already been used since 1906 for an unrelated organism, Alexander Janke proposed an alternative name, ''Klöckeria'', for the genus in 1923, which he corrected in 1928 to ''Kloeckera''. Jacomina Lodder in 1934 found the yeast to be identical to another species, ''Kloeckera jensenii'', also isolated by Klöcker in 1912, and reclassified it as a

synonym A synonym is a word, morpheme, or phrase that means exactly or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are all ...

of ''Kloeckera jensenii''. A similar process occurred with yeasts identified by Klöcker as ''Pseudosaccharomyces indicus'', ''Pseudosaccharomyces antillarum'', and ''Pseudosaccharomyces willi'', which Janke moved to ''Kloeckera indica'', ''Kloeckera antillarum'', and ''Kloeckera willi'', and Lodder identified as three strains of the same species, consolidated into ''Kloeckera antillarum''. Further study by Miller and Phaff in 1958 found that ''Kloeckera jensenii'', ''Kloeckera javanica'' (originally ''Pseudosaccharomyces javanicus''), ''Kloeckera lafarii'', and ''Kloeckera antillarum'' were so similar to each other that they should be further combined into one species, ''Kloeckera javanica''. In 1974, yeast researcher Maudy Th. Smith observed a teleomorphic stage of the type strain of the original ''Kloeckera occidentalis'' yeast strain. As was custom at the time, teleomorphic forms of ''Kloeckera'' yeasts were identified as separate species in the ''Hanseniaspora'' genus, so it was designated as ''Hanseniaspora occidentalis''. DNA Testing by S.A. Meyer in 1978 conclusively synonymized the anamorphic yeasts in the ''Kloeckera'' genus with their teleomorphic counterparts in the ''Hanseniaspora'' genus, and identified ''Kloeckera javanica'' as a synonym of ''Hanseniaspora occidentalis''.

Description

Microscopic examination of the yeast cells in YM liquid medium after 48 hours at 25°C reveals cells that are 1.8 to 6.2 μm by 3 to 11 μm in size,

apiculate The following is a list of terms which are used to describe leaf morphology in the description and taxonomy of plants. Leaves may be simple (a single leaf blade or lamina) or compound (with several leaflets). The edge of the leaf may be regular o ...

ovoid An oval () is a closed curve in a plane which resembles the outline of an egg. The term is not very specific, but in some areas (projective geometry, technical drawing, etc.) it is given a more precise definition, which may include either one or ...

or sometimes spherical, appearing singly or in pairs. Reproduction is by

budding Budding or blastogenesis is a type of asexual reproduction in which a new organism develops from an outgrowth or bud due to cell division at one particular site. For example, the small bulb-like projection coming out from the yeast cell is know ...

, which occurs at both poles of the cell. In broth culture, sediment is present, and after one month a thin ring is formed. Colonies that are grown on malt agar for one month at 25°C appear white to cream-colored, glossy, and smooth. Growth is flat on the edges and slightly raised at the center. The yeast generally does not form

pseudohyphae A hypha (; ) is a long, branching, filamentous structure of a fungus, oomycete, or actinobacterium. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium. Structure A hypha consists of one or ...

on potato agar, but some strains have been observed to form either poorly-developed or well-developed pseudohyphae. The yeast has been observed to form one or two sherical and smooth

ascospores 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 ...

with an equatorial ledge when grown for at least one week on 5% Difco malt extract agar. The yeast can ferment

glucose Glucose is a simple sugar with the molecular formula . Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, using ...

and

sucrose Sucrose, a disaccharide, is a sugar composed of glucose and fructose subunits. It is produced naturally in plants and is the main constituent of white sugar. It has the molecular formula . For human consumption, sucrose is extracted and refined ...

, but not

galactose Galactose (, '' galacto-'' + '' -ose'', "milk sugar"), sometimes abbreviated Gal, is a monosaccharide sugar that is about as sweet as glucose, and about 65% as sweet as sucrose. It is an aldohexose and a C-4 epimer of glucose. A galactose molec ...

maltose } Maltose ( or ), also known as maltobiose or malt sugar, is a disaccharide formed from two units of glucose joined with an α(1→4) bond. In the isomer isomaltose, the two glucose molecules are joined with an α(1→6) bond. Maltose is the two- ...

lactose Lactose is a disaccharide sugar synthesized by galactose and glucose subunits and has the molecular formula C12H22O11. Lactose makes up around 2–8% of milk (by mass). The name comes from ' (gen. '), the Latin word for milk, plus the suffix '' - ...

raffinose Raffinose is a trisaccharide composed of galactose, glucose, and fructose. It can be found in beans, cabbage, brussels sprouts, broccoli, asparagus, other vegetables, and whole grains. Raffinose can be hydrolyzed to D-galactose and sucrose by ...

trehalose Trehalose (from Turkish '' tıgala'' – a sugar derived from insect cocoons + -ose) is a sugar consisting of two molecules of glucose. It is also known as mycose or tremalose. Some bacteria, fungi, plants and invertebrate animals synthesize it ...

. The yeast can assimilate glucose, sucrose,

cellobiose Cellobiose is a disaccharide with the formula (C6H7(OH)4O)2O. It is classified as a reducing sugar. In terms of its chemical structure, it is derived from the condensation of a pair of β-glucose molecules forming a β(1→4) bond. It can be hyd ...

, and

salicin Salicin is an alcoholic β-glucoside. Salicin is produced in (and named after) willow (''Salix'') bark. It is a biosynthetic precursor to salicylaldehyde. Medicinal aspects Salicin is found in the bark of and leaves of willows, poplars and va ...

. Assimilation of

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 ...

is variable. It has a positive growth rate at 30°C, but no growth at 37°C. It can not grow on agar media containing 0.1% cycloheximide and can not utilize 2-keto-d-gluconate as a sole source of carbon.

Ecology

The type species of the original ''Pseudosaccharomyces occidentalis'' strain was isolated from a soil sample in

Saint Croix Saint Croix; nl, Sint-Kruis; french: link=no, Sainte-Croix; Danish and no, Sankt Croix, Taino: ''Ay Ay'' ( ) is an island in the Caribbean Sea, and a county and constituent district of the United States Virgin Islands (USVI), an unincorpo ...

, and other samples have been isolated from soil in

Java Java (; id, Jawa, ; jv, ꦗꦮ; su, ) is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea to the north. With a population of 151.6 million people, Java is the world's List ...

and Saint Thomas. It has also been collected from ''

Drosophila ''Drosophila'' () is a genus of flies, belonging to the family Drosophilidae, whose members are often called "small fruit flies" or (less frequently) pomace flies, vinegar flies, or wine flies, a reference to the characteristic of many species ...

'' species in Brazil. Samples of a variant of the species, proposed as var. ''citrica'', have been collected from orange juice in Italy and rotten oranges in Argentina. It is also commonly found in vineyards and the fruit flies that populate vineyards. A 2022 study found that Muscaris wine must aerobically innoculated with ''Hanseniaspora occidentalis'' for three days followed by the addition of commercial wine yeast resulted in an almost complete elimination of

in the wine, and produced a three-fold increase in

ethyl acetate Ethyl acetate ( systematically ethyl ethanoate, commonly abbreviated EtOAc, ETAC or EA) is the organic compound with the formula , simplified to . This colorless liquid has a characteristic sweet smell (similar to pear drops) and is used in glues ...

References

{{Taxonbar, from=Q80924735 Saccharomycetes Yeasts Fungi described in 1974