''Inonotus obliquus'', commonly called chaga (a Latinisation of the Russian word ''чага''), is a

fungus A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately fr ...

in the family

Hymenochaetaceae The ''Hymenochaetaceae'' are a family of fungi in the order Hymenochaetales. The family contains several species that are implicated in many diseases of broad-leaved and coniferous trees, causing heart rot, canker and root diseases, and also es ...

. It is

parasitic Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson ha ...

birch A birch is a thin-leaved deciduous hardwood tree of the genus ''Betula'' (), in the family Betulaceae, which also includes alders, hazels, and hornbeams. It is closely related to the beech- oak family Fagaceae. The genus ''Betula'' cont ...

and other trees. The sterile

conk The conk was a hairstyle popular among African-American men from the 1920s up to early-mid 1960s. This hairstyle called for a man with naturally "kinky" hair to have it chemically straightened using a relaxer called congolene, an initiall ...

is irregularly formed and resembles burnt charcoal. It is not the

fruiting body The sporocarp (also known as fruiting body, fruit body or fruitbody) of fungi is a multicellular structure on which spore-producing structures, such as basidia or asci, are borne. The fruitbody is part of the sexual phase of a fungal life cy ...

of the fungus, but a sclerotium or mass of

mycelium Mycelium (plural mycelia) is a root-like structure of a fungus consisting of a mass of branching, thread-like hyphae. Fungal colonies composed of mycelium are found in and on soil and many other substrates. A typical single spore germinates ...

, mostly black because of a great amount of

melanin Melanin (; from el, μέλας, melas, black, dark) is a broad term for a group of natural pigments found in most organisms. Eumelanin is produced through a multistage chemical process known as melanogenesis, where the oxidation of the amino ...

. Some people consider chaga medicinal. ''Inonotus obliquus'' is found most commonly in the

Circumboreal Region The Circumboreal Region in phytogeography is a floristic region within the Holarctic Kingdom in Eurasia and North America, as delineated by such geobotanists as Josias Braun-Blanquet and Armen Takhtajan. It is the largest floristic region i ...

of the Northern Hemisphere, where it is distributed in birch forests.

Common names

The name ''chaga'' () comes from the Russian name of the fungus, russian: чага, translit=čaga, label=none, which in turn is borrowed from the word for "mushroom" in Komi, kv, тшак, translit=tšak, label=none, the language of the

indigenous peoples Indigenous peoples are culturally distinct ethnic groups whose members are directly descended from the earliest known inhabitants of a particular geographic region and, to some extent, maintain the language and culture of those original people ...

in the Kama River Basin, west of the

Ural Mountains The Ural Mountains ( ; rus, Ура́льские го́ры, r=Uralskiye gory, p=ʊˈralʲskʲɪjə ˈɡorɨ; ba, Урал тауҙары) or simply the Urals, are a mountain range that runs approximately from north to south through western ...

. It is also known as the

clinker Clinker may refer to: *Clinker (boat building), construction method for wooden boats *Clinker (waste), waste from industrial processes *Clinker (cement), a kilned then quenched cement product * ''Clinkers'' (album), a 1978 album by saxophonist St ...

polypore, cinder conk, black mass and birch canker polypore. In

England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe ...

and officially in

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by to ...

, it is known as the sterile conk trunk rot of

Morphology

''Inonotus obliquus'' causes a white heart rot to develop in the host tree. The chaga spores enter the tree through wounds, particularly poorly healed branch stubs. The white rot decay will spread throughout the

heartwood Wood is a porous and fibrous structural tissue found in the stems and roots of trees and other woody plants. It is an organic materiala natural composite of cellulose fibers that are strong in tension and embedded in a matrix of lignin t ...

of the host. During the infection cycle, penetration of the sapwood occurs only around the sterile exterior

mass. The chaga fungus will continue to cause decay within the living tree for 10–80+ years. While the tree is alive, only sterile mycelial masses are produced (the black exterior conk). The sexual stage begins after the tree, or some portion of the tree, is killed by the infection. ''I. obliquus'' will begin to produce fertile fruiting bodies underneath the bark. These bodies begin as a whitish mass that turn to brown with time. Since the sexual stage occurs almost entirely under the bark, the fruiting body is rarely seen. These fruiting bodies produce

basidiospore A basidiospore is a reproductive spore produced by Basidiomycete fungi, a grouping that includes mushrooms, shelf fungi, rusts, and smuts. Basidiospores typically each contain one haploid nucleus that is the product of meiosis, and they are ...

s which will spread the infection to other vulnerable trees.

Distribution and cultivation

Generally found growing on birch (''

Betula A birch is a thin-leaved deciduous hardwood tree of the genus ''Betula'' (), in the family Betulaceae, which also includes alders, hazels, and hornbeams. It is closely related to the beech- oak family Fagaceae. The genus ''Betula'' contains 30 t ...

'' spp.) trees, it has also been found on alder (''

Alnus Alders are trees comprising the genus ''Alnus'' in the birch family Betulaceae. The genus comprises about 35 species of monoecious trees and shrubs, a few reaching a large size, distributed throughout the north temperate zone with a few s ...

'' spp.), beech (''

Fagus Beech (''Fagus'') is a genus of deciduous trees in the family Fagaceae, native to temperate Europe, Asia, and North America. Recent classifications recognize 10 to 13 species in two distinct subgenera, ''Engleriana'' and ''Fagus''. The ''Engle ...

'' spp.) and poplar (''

Populus ''Populus'' is a genus of 25–30 species of deciduous flowering plants in the family Salicaceae, native to most of the Northern Hemisphere. English names variously applied to different species include poplar (), aspen, and cottonwood. The we ...

'' spp.). In species other than birch, the fungus often appears as buried stem canker, instead of the charcoal-like mass found on birch trees. Attempts at

cultivating Tillage is the agricultural preparation of soil by mechanical agitation of various types, such as digging, stirring, and overturning. Examples of human-powered tilling methods using hand tools include shoveling, picking, mattock work, hoeing, ...

this fungus on

potato dextrose agar Potato dextrose agar (BAM Media M127
from the U.S.

and other simulated

mediums Mediumship is the practice of purportedly mediating communication between familiar spirits or spirits of the dead and living human beings. Practitioners are known as "mediums" or "spirit mediums". There are different types of mediumship or spir ...

resulted in a reduced and markedly different production of metabolites. Cultivated chaga developed a reduced number of

phytosterol Phytosterols are phytosteroids, similar to cholesterol, that serve as structural components of biological membranes of plants. They encompass plant sterols and stanols. More than 250 sterols and related compounds have been identified. Free phyt ...

s, particularly

lanosterol Lanosterol is a tetracyclic triterpenoid and is the compound from which all animal and fungal steroids are derived. By contrast plant steroids are produced via cycloartenol. Role in biosynthesis of other steroids Elaboration of lanosterol under en ...

, an intermediate in the synthesis of

ergosterol Ergosterol (ergosta-5,7,22-trien-3β-ol) is a sterol found in cell membranes of fungi and protozoa, serving many of the same functions that cholesterol serves in animal cells. Because many fungi and protozoa cannot survive without ergosterol, t ...

and lanostane-type

triterpene Triterpenes are a class of chemical compounds composed of three terpene units with the molecular formula C30H48; they may also be thought of as consisting of six isoprene units. Animals, plants and fungi all produce triterpenes, including squa ...

Chemistry

The black sclerotium has large concentrations of

. Chaga contains extremely high concentrations of

oxalate Oxalate (IUPAC: ethanedioate) is an anion with the formula C2O42−. This dianion is colorless. It occurs naturally, including in some foods. It forms a variety of salts, for example sodium oxalate (Na2C2O4), and several esters such as dimethyl ...

, 2800–11200 mg total oxalates/100 g sclerotium, one of the highest reported in any organism.

Preparation

Chaga is traditionally grated into a fine powder and used to brew a beverage resembling

coffee Coffee is a drink prepared from roasted coffee beans. Darkly colored, bitter, and slightly acidic, coffee has a stimulating effect on humans, primarily due to its caffeine content. It is the most popular hot drink in the world. Seeds of ...

or tea and tastes strongly of

Chinese herbal tea Lingnan culture, or Cantonese culture, refers to the regional Chinese culture of the region of Lingnan: twin provinces of Guangdong and Guangxi, the names of which mean "eastern expanse" and "western expanse" respectively. Strictly speaking, th ...

. However, caution is warranted with chronic use due to the extremely high concentrations of

oxalates Oxalate (IUPAC: ethanedioate) is an anion with the formula C2O42−. This dianion is colorless. It occurs naturally, including in some foods. It forms a variety of salts, for example sodium oxalate (Na2C2O4), and several esters such as dimethyl o ...

in chaga. Three extraction processes may be used. * Hot water extraction is certainly the most common preparation. A decoction is created by simmering, blocklike pieces of the chaga in numerous quarts of water until the water is reduced and the remaining liquid contains a portion of the chaga's concentrated water-soluble compounds. Such preparations, produced in China and Japan, are exported worldwide. The ß-D-glucans may have a content of approximately 35% in a pure extract. If chaga tea is prepared at home, the chaga chunks can be reused multiple times. *

Ethanol Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an alcohol with the chemical formula . Its formula can be also written as or (an ethyl group linked to a ...

methanol Methanol (also called methyl alcohol and wood spirit, amongst other names) is an organic chemical and the simplest aliphatic alcohol, with the formula C H3 O H (a methyl group linked to a hydroxyl group, often abbreviated as MeOH). It is ...

extraction isolates the water-insoluble components,

betulinic acid Betulinic acid is a naturally occurring pentacyclic triterpenoid which has antiretroviral, antimalarial, and anti-inflammatory properties, as well as a more recently discovered potential as an anticancer agent, by inhibition of topoisomerase. It ...

betulin Betulin is an abundant, naturally occurring triterpene. It is commonly isolated from the bark of birch trees. It forms up to 30% of the dry weight of silver birch bark. It is also found in birch sap. ''Inonotus obliquus'' and red alder also conta ...

and the phytosterols. This extraction process is in general used as a second step after hot-water extraction, since ethanol alone will not break down

chitin Chitin ( C8 H13 O5 N)n ( ) is a long-chain polymer of ''N''-acetylglucosamine, an amide derivative of glucose. Chitin is probably the second most abundant polysaccharide in nature (behind only cellulose); an estimated 1 billion tons of chit ...

effectively—heat is essential. *

Fermentation Fermentation is a metabolic process that produces chemical changes in organic substrates through the action of enzymes. In biochemistry, it is narrowly defined as the extraction of energy from carbohydrates in the absence of oxygen. In food p ...

is the most time-consuming and most expensive. Because fermentation methods are not standardized (many types of bacteria and fungi can be used in the process), the outcome is also not standardized.

References