''Pichia kudriavzevii'' (formerly ''Candida krusei''
) is a budding
yeast
Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom (biology), kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are est ...
(a species of
fungus
A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...
) involved in
chocolate
Chocolate is a food made from roasted and ground cocoa beans that can be a liquid, solid, or paste, either by itself or to flavoring, flavor other foods.
Cocoa beans are the processed seeds of the cacao tree (''Theobroma cacao''); unprocesse ...
production. ''P. kudriavzevii'' is an emerging fungal
nosocomial
A hospital-acquired infection, also known as a nosocomial infection (from the Greek , meaning "hospital"), is an infection that is acquired in a hospital or other healthcare facility. To emphasize both hospital and nonhospital settings, it is s ...
pathogen
In biology, a pathogen (, "suffering", "passion" and , "producer of"), in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a Germ theory of d ...
primarily found in the immunocompromised and those with hematological malignancies. It has natural
resistance to
fluconazole
Fluconazole is an antifungal medication used for a number of fungal infections. These include candidiasis, blastomycosis, coccidioidomycosis, cryptococcosis, histoplasmosis, dermatophytosis, and tinea versicolor. It is also used to pr ...
, a standard antifungal agent. It is most often found in patients who have had prior fluconazole exposure, sparking debate and conflicting evidence as to whether fluconazole should be used prophylactically. Mortality due to ''P. kudriavzevii''
fungemia is much higher than the more common ''C. albicans''. Other ''
Candida
Candida, or Cándida (Spanish), may refer to:
Biology and medicine
* ''Candida'' (fungus), a genus of yeasts
** Candidiasis, an infection by ''Candida'' organisms
* Malvasia Candida, a variety of grape
Places
* Candida, Campania, a ''comu ...
'' species that also fit this profile are ''C. parapsilosis'', ''C. glabrata'', ''C. tropicalis'', ''C. guillermondii'' and ''C. rugosa''.
''P. kudriavzevii'' can be successfully treated with
voriconazole
Voriconazole, sold under the brand name Vfend among others, is an antifungal medication used to treat a number of fungal infections. This includes aspergillosis, candidiasis, coccidioidomycosis, histoplasmosis, penicilliosis, and infections b ...
,
amphotericin'' ''B, and echinocandins (
micafungin
Micafungin, sold under the brand name Mycamine, is an echinocandin antifungal medication used to treat and prevent invasive fungal infections including candidemia, abscesses, and esophageal candidiasis. It inhibits the production of beta-1,3 ...
,
caspofungin
Caspofungin ( INN; brand name Cancidas) is a lipopeptide antifungal drug from Merck & Co., Inc. It is a member of a class of antifungals termed the echinocandins. It works by inhibiting the enzyme (1→3)-β-D-glucan synthase and thereby di ...
, and
anidulafungin
Anidulafungin (INN) (sold under the brand name Eraxis among others, is a semisynthetic echinocandin used as an antifungal medication. It may also have application in treating invasive ''Aspergillus'' infection when used in combination with vo ...
).
Role in chocolate production
Cacao beans have to be
fermented
Fermentation is a type of anaerobic metabolism which harnesses the redox potential of the reactants to make adenosine triphosphate (ATP) and organic end products. Organic compound, Organic molecules, such as glucose or other sugars, are Catabo ...
to remove the bitter taste and break them down. This takes place with two fungi: ''P. kudriavzevii'' and ''
Geotrichum''. Most of the time, the two fungi are already present on the
seed pods and
seed
In botany, a seed is a plant structure containing an embryo and stored nutrients in a protective coat called a ''testa''. More generally, the term "seed" means anything that can be Sowing, sown, which may include seed and husk or tuber. Seeds ...
s of the cacao plant, but specific strains are used in modern chocolate making. Each chocolate company uses its own strains, which have been selected to provide optimum flavor and aroma to the chocolate.
The yeasts produce enzymes to break down the pulp on the outside of the beans and generate
acetic acid
Acetic acid , systematically named ethanoic acid , is an acidic, colourless liquid and organic compound with the chemical formula (also written as , , or ). Vinegar is at least 4% acetic acid by volume, making acetic acid the main compone ...
, killing the cacao embryo inside the seed, developing a chocolatey aroma and eliminating the bitterness in the beans.
Growth and metabolism
''P. kudriavzevii'' grows best at a temperature of . Other ''Candida'' species are a major differential diagnosis and these generally require biotin for growth and some have additional vitamin requirements, but ''P. kudriavzevii'' can grow in vitamin-free media. Also, ''P. kudriavzevii'' grows on Sabouraud's dextrose agar as spreading colonies with a matte or a rough whitish-yellow surface, in contrast to the convex colonies of ''Candida'' spp. This characteristic, together with its "long grain rice" appearance on microscopy, helps the definitive identification of the species.
References
Further reading
*
*
External links
*
Food microbiology
Yeasts
Chocolate industry
Pathogenic microbes
Fungal pathogens of humans
Animal fungal diseases
Fungus species
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