Pichia

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Pichia
Systematics
Department : Ascomycota mushrooms
Subdivision : Saccharomycotina
Class : Saccharomycetes
Order : Real yeast (Saccharomycetales)
Family : Pichiaceae
Genre : Pichia
Scientific name
Pichia
EC Hansen

Pichia (synonym Hansenula ) is a genus of real yeast .

features

Microscopic features

The cells are elongated with spherical, ovoid or short. Asexual reproduction occurs through multilateral shoot formation , which occurs from a narrow base. Pichia is a teleomorph and forms asci that are unconjugated or show a conjunction between mother cell and bud or between independent cells. Some species are heterothallic , but others are homothallic . In the asci, 1–4, rarely 5–8, hat-shaped, hemispherical, Saturn-shaped or round ascospores are formed, which can be smooth or rough.

Physiological / biochemical characteristics

No carbohydrates other than glucose are fermented. Few sugars and other carbon sources are assimilated. Unlike other yeasts and related genera, nitrate is not used as a source of nitrogen. The coenzyme Q7 is formed. The diazonium blue B reaction is negative.

ecology

Many species can be found in rotting plants such as Pichia membranaefaciens . The species can also be found in fermented beverages. Some species interfere with the fermentation process in alcohol production . Komagataella phaffii ( Pichia pastoris ) is often used as an expression system in biotechnology . Ogataea angusta ( Pichia angusta ), also known as Hansenula polymorpha or H. angusta , is a model organism for studying the functions of peroxisomes and the molecular biology on which their functions are based .

Systematics

Emil Christian Hansen described the genus for the first time in 1904. After union with Hansenula, over 100 species were counted to the genus Pichia . The original separation was done because Hansenula species can assimilate nitrate. However, this feature to separate genus was later recognized as insufficient and Hansenula was combined with Pichia . The genus was long with the Saccharomycetaceae within the real yeasts. It now forms its own family, the Pichiaceae, together with three other genera ( Dekkera , Kregervanrija , Saturnispora ). Since the genus itself was polyphyletic, however, the genera Ogataea , Komagataella , Hyphopichia , Kodamaea , Kregervanrija , Nakazawaea , Pfaffomyces , Saturnispora , Lindneria , Starmera , Wickerhamomyces , Zygoascus and other genera were separated. In 2018, the industrially used species P. kudriavzevii was found to be identical to Candida krusei (syn. C. glycerinogenes ). There remained around 20 species with the type Pichia membranifaciens :

supporting documents

  1. ↑ a b c d Cletus Kurtzman: Chapter 57: Pichia. In: Cletus Kurtzman, JW Fell, Teun Boekhout (Eds.): The Yeasts A Taxonomic Study. Volume 1, Elsevier, 2010, ISBN 978-0-444-52149-1 , pp. 685 ff. (Online)
  2. ↑ Cletus Kurtzman, JW Fell, Teun Boekhout (eds.): The Yeasts: A Taxonomic Study. Volume 1, Elsevier, 2010, ISBN 978-0-444-52149-1 , p. 698 ff.
  3. ↑ JL Cereghino, JM Cregg: Heterologous protein expression in the methylotrophic yeast Pichia pastoris. In: FEMS Microbiology Reviews. 24, 2000, pp. 45-66.
  4. ↑ G. Gellissen (Ed.): Production of recombinant proteins - novel microbial and eukaryotic expression systems. Wiley-VCH, Weinheim 2005, ISBN 3-527-31036-3 .
  5. ↑ Cletus Kurtzman: Chapter 13: Discussion of Teleomorphic and Anamorphic Ascomycetous Yeasts and Yeast-like Taxa. In: Cletus Kurtzman, JW Fell, Teun Boekhout (Eds.): The Yeasts: A Taxonomic Study. Volume 1, Elsevier, 2010, ISBN 978-0-444-52149-1 , p. 293 ff. (Online)
  6. ↑ Alexander P. Douglass, Benjamin Offei, Stephanie Braun-Galleani, Aisling Y. Coughlan, Alexandre AR Martos, Raúl A. Ortiz-Merino, Kevin P. Byrne, Kenneth H. Wolfe: Population genomics shows no distinction between pathogenic Candida krusei and environmental Pichia kudriavzevii : One species, four names , in: PLOS Pathogenes from July 19, 2018, doi: 10.1371 / journal.ppat.1007138
  7. ↑ Yeast with a dangerous double life , on: Scinexx of July 23, 2018