An anaerobic organism or anaerobe is any organism that does not require molecular oxygen for growth. It may react negatively or even die if free oxygen is present. In contrast, an aerobic organism (aerobe) is an organism that requires an oxygenated environment. Anaerobes may be unicellular or multicellular. Most fungi are obligate aerobes, requiring oxygen to survive. However, some species, such as the Chytridiomycota that reside in the rumen of cattle, are obligate anaerobes; for these species, anaerobic respiration is used because oxygen will disrupt their metabolism or kill them. Deep waters of the ocean are a common anoxic environment.
Chytridiomycota are a division of zoosporic organisms in the kingdom Fungi, informally known as chytrids. The name is derived from the Ancient Greek χυτρίδιον, meaning "little pot", describing the structure containing unreleased zoospores. Chytrids are one of the earliest diverging fungal lineages, and their membership in kingdom Fungi is demonstrated with chitin cell walls, a posterior whiplash flagellum, absorptive nutrition, use of glycogen as an energy storage compound, and synthesis of lysine by the α-amino adipic acid (AAA) pathway.
A zoospore is a motile asexual spore that uses a flagellum for locomotion in aqueous or moist environments. Also called a swarm spore, these spores are created by some protists, bacteria, and fungi to propagate themselves. Certain zoospores are infectious and transmittable, such as Batrachochytrium dendrobatidis, a fungal zoospore that causes high rates of mortality in amphibians.
Neocallimastigomycota is a phylum containing anaerobic fungi, which are symbionts found in the digestive tracts of larger herbivores. Anaerobic fungi were originally placed within phylum Chytridiomycota, within Order Neocallimastigales but later raised to phylum level, a decision upheld by later phylogenetic reconstructions. It encompasses only one family.
Hyphochytrids are eukaryotic organisms in the group of Stramenopiles (Heterokonta).
In botany, a zoid or zoïd is a reproductive cell that possesses one or more flagella, and is capable of independent movement. Zoid can refer to either an asexually reproductive spore or a sexually reproductive gamete. In sexually reproductive gametes, zoids can be either male or female depending on the species. For example, some brown alga (Phaeophyceae) reproduce by producing multi-flagellated male and female gametes that recombine to form the diploid sporangia. Zoids are primarily found in some protists, diatoms, green alga, brown alga, non-vascular plants, and a few vascular plants. The most common classification group that produces zoids is the heterokonts or stramenopiles. These include green alga, brown alga, oomycetes, and some protists. The term is generally not used to describe motile, flagellated sperm found in animals. Zoid is also commonly confused for zooid which is a single organism that is part of a colonial animal.
Fungi of the order Chytridiales, like other members of its division, may either have a monocentric thallus or a polycentric rhizomycelium. When the ribosomal genes of members classified in this order were first examined using molecular techniques, it was discovered that the order contained some species that were not related. With the culture and characterization of Chytridium olla, the type species of this order, the limits of the Chytridiales were established. The Chytridiales is now monophyletic and species such as Polychytrium aggregatum, Chytriomyces angularis and Cladochytrium replicatum have been transferred to other orders.
Rhizophydiales are an important group of chytrid fungi. They are found in soil as well as marine and fresh water habitats where they function as parasites and decomposers.
Blastocladiomycota is one of the currently recognized phyla within the kingdom Fungi. Blastocladiomycota was originally the order Blastocladiales within the phylum Chytridiomycota until molecular and zoospore ultrastructural characters were used to demonstrate it was not monophyletic with Chytridiomycota. The order was first erected by Petersen for a single genus, Blastocladia, which was originally considered a member of the oomycetes. Accordingly, members of Blastocladiomycota are often referred to colloquially as "chytrids." However, some feel "chytrid" should refer only to members of Chytridiomycota. Thus, members of Blastocladiomyota are commonly called "blastoclads" by mycologists. Alternatively, members of Blastocladiomycota, Chytridiomycota, and Neocallimastigomycota lumped together as the zoosporic true fungi. Blastocladiomycota contains 5 families and approximately 12 genera. This early diverging branch of kingdom Fungi is the first to exhibit alternation of generations. As well, two (once) popular model organisms—Allomyces macrogynus and Blastocladiella emersonii—belong to this phylum.
Neocallimastix is a genus of obligately anaerobic rumen fungi in the family Neocallimastigaceae. A specialised group of chytrids grow in the rumen of herbivorous animals, where they degrade cellulose and thus play a primary role in the complex microbial ecology of the rumen.
Piromyces is a genus of fungi in the family Neocallimastigaceae.
Rozella is a fungal genus of obligate endoparasites of a variety of hosts, including Oomycota, Chytridiomycota, and Blastocladiomycota. Rozella was circumscribed by French mycologist Marie Maxime Cornu in 1872. Considered one of the earliest diverging lineages of fungi, the widespread genus contains 27 species, with the most well studied being Rozella allomycis. Rozella is a member of a large clade of fungi referred to as the Cryptomycota/Rozellomycota. While some can be maintained in dual culture with the host, most have not been cultured, but they have been detected, using molecular techniques, in soil samples, and in freshwater and marine ecosystems. Zoospores have been observed, along with cysts, and the cells of some species are attached to diatoms.
Synchytrium is a large genus of plant pathogens within the phylum Chytridiomycota. Species are commonly known as false rust or wart disease. Approximately 200 species are described, and all are obligate parasites of angiosperms, ferns, or mosses. Early species were mistakenly classified among the higher fungi because of their superficial similarity to the rust fungi. Anton de Bary and Mikhail S. Woronin recognized the true nature of these fungi and established the genus to accommodate Synchytrium taraxaci, which grows on dandelions, and S. succisae, which grows on Succisa pratensis. Synchytrium taraxaci is the type of the genus. The genus has been divided into 6 subgenera based on differences in life cycles.
Olpidium is a fungal genus in the family Olpidiaceae. Members of Olpidium are zoosporic pathogens of plants, animals, fungi, and oomycetes.
Physoderma is a genus of chytrid fungi. Described by German botanist Karl Friedrich Wilhelm Wallroth in 1833, the genus contains some species that are parasitic on vascular plants, including P. alfalfae and P. maydis, causative agents of crown wart of alfalfa and brown spot of corn, respectively. Of the chytrid genera, Physoderma is the oldest. However, species were confused with the rust fungi, the genus Synchytrium, and the genus Protomyces of Ascomycota. Members of Physoderma are obligate parasites of pteridophytes and angiosperms. There are approximately 80 species within this genus.
Acetitomaculum ruminis is a Gram-positive bacterium species from the genus of Acetitomaculum which has been isolated from the rumen of a bovine in the United States. Acetitomaculum ruminis utilize formate, glucose and CO2.
Thraustochytrids are single-celled saprotrophic eukaryotes (decomposers) that are widely distributed in marine ecosystems, and which secrete enzymes including, but not limited to amylases, proteases, phosphatases. They are most abundant in regions with high amounts of detritus and decaying plant material. They play an important ecological role in mangroves, where they aid in nutrient cycling by decomposing decaying matter. Additionally, they contribute significantly to the synthesis of omega-3 polyunsaturated fatty acids (PUFAs): docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA), which are essential fatty acids for the growth and reproduction of crustaceans. Thraustochytrids are members of the class Labyrinthulea, a group of protists that had previously been incorrectly categorized as fungi due to their similar appearance and lifestyle. With the advent of DNA sequencing technology, labyrinthulomycetes were appropriately placed with other stramenopiles and subsequently categorized as a group of Labyrinthulomycetes.
Anaeromyces robustus is a fungal microorganism that lives in the gut rumen of many ruminant herbivores such as cows and sheep. Previously thought to be protozoa from their flagellated zoospores, they are biomass degraders and help the animal by breaking down carbohydrates and plant materials from the food the animal ingests. This fungus, therefore, is anaerobic and lives without oxygen. Gut fungi are dramatically outnumbered by other organisms in the microbiome; however, they are important members of the gut microbiome in ruminants and hind-gut fermenters and play a key role in digestion.
Aphelidium tribonemae is a species within the Aphelid group. Their classification in the kingdom Fungi is a subject of controversy. Some argue for the classification of aphelids as ‘fungal animals', and for a period of time in the 1950s, aphids were classified as protists due to their amoeboid stage. Recently, molecular phylogenetics placed the aphelids within Opisthosporidia, a super phylum within Opisthokonta. Aphelids have posterior uniflagellate zoospores which place them as Opisthokonts. They are an early diverging lineage in Kingdom Fungi. While the aphelid group only contains three genera, it spans many both freshwater and marine ecosystems.
Marilyn Rose Noyes Mollicone was an American botanist advancing mycology in Maine and advocating for naturalist education.
