Mucor mucedo | |
---|---|
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Fungi |
Division: | Mucoromycota |
Class: | Mucoromycetes |
Order: | Mucorales |
Family: | Mucoraceae |
Genus: | Mucor |
Species: | M. mucedo |
Binomial name | |
Mucor mucedo Linnaeus (1753) | |
Synonyms | |
|
Mucor mucedo, commonly known as the common pinmould, [1] is a fungal plant pathogen and member of the phylum Mucoromycota and the genus Mucor . [2] Commonly found on soil, dung, water, plants and moist foods, Mucor mucedo is a saprotrophic fungus found world-wide with 85 known strains. [3] [4] It is often mistaken for Rhizopus rots on fruits (i.e. strawberries) due to similar mould growth shape and colour. [5] Contrastingly, however, Mucor mucedo is found to grow on a wide range of stored grains and plants, including cucumber and tomato. [6] [7] Discovered in Italy in 1729 by P.A. Micheli and later noted by Carl Linnaeus in 1753 in the Species Plantarum , Mucor mucedo was originally classified as Mucor vulgaris by Micheli but later classified synonymous under name Mucor mucedo. [8] The species was redescribed as Ascophora mucedo by H.J. Tode in 1790 but this type resided in a stoloniferous habitat and was later made the type of new genus Rhizopus . [9] [10]
Mucor mucedo has fast growing colonies and are characterized by tall, simple, unbranched sporangiophores lacking basal rhizoids, non-apophysate sporangia, and pigmented zygosporangial walls. [11] [12] The walls are covered with granules and the swollen apex contains spores that are white or yellow in when immature, and upon maturation appear brownish grey or dark grey. [8] [13] Colonies commonly have a fluffy appearance with heights of up to several centimeters, resembling cotton candy, and the hyphae are non-septate or sparsely septate. [14] Mucor mucedo is heterothallic, and both (+) and (-) mating strains are morphologically indistinguishable although isolates of the (-) strain may exhibit less vigorous mycelial growth in cultivation. [13] The zygophores are highly differentiated from sporangiophores and are known to rarely bare sporangia. [13] [15] Mucor mucedo morphology and growth is influenced by temperature: [16]
Mucor mucedo reproduction occurs in asexual and sexual methods.
Mucor mucedo is also influenced by light, as cultures grown during the day at 20 °C mainly produced tall sporangiophores, rarely producing short sporangiophores or none at all. [16] Cultures drown in the dark grew a dense layer of short sporangiophores with occasional tall ones. [16] A wide range of growth media can be used, but most Mucor mucedo fungi appear to grow well with good mycelial growth and sporulation on pumpkin and sweet potato as well as potato dextrose agar (PDA), consisting of potato starch and dextrose as key carbon sources, due to its rich nutrient availability. [14] [17] An optimal phospholipid environment has been found to be necessary for the normal apical growth and hyphal branching in Mucor mucedo, specifically with dimyristoyl phosphatidylcholine shown to stimulate chitinase activity. [18] Chitinases and chitin synthases are regulated for the lysis and synthesis of the major cell wall component chitin, and have important morphogenetic roles in hyphal growth. [18] [19] Both are inactivated when treated with phospholipases and growth is shunted [19] Chitin synthase activity can also be inhibited by anethole, which is a major component of anise oil that has weak antimicrobial activity with broad antimicrobial spectrum. [20]
Asexual reproduction occurs by the formation of uninucleate, haploid sporangiospores in the sporangia, on the terminal ends of the aerial sporangiophores. In the sporangia, there is an accumulation of nutrients, cytoplasm, and nuclei. An extension of the sporangiophore called the columella protrudes into the sporangium, and upon the maturation of the sporangiospores, burst of the sporangium allows for the dispersion of the spores, where wind is the primary dissemination method. [11] [13] Asexual reproduction may be favoured in unfavourable environmental conditions, as this inhibits the conjugation between the two sexual strains. [13] The (-) strain loses sexual capacity faster than the (+) strain. [13]
As Mucor mucedo are heterothallic, the hyphae taking part in the sexual reproduction have to be of two different strains, either (+) or (-). When these make contact an extension of the hyphae called progametangia are formed and most of the nuclei and cytoplasm accumulate at the ends. [11] [13] Septa form adjacent to the point of contact, and the terminal component, gametangia, are visible with elongated cells called suspensors attached to it. As the gametangia grow and after numerous mitotic divisions, the gametangial wall proceeds to dissolve and gametes found inside fuse, producing a zygote. This zygospore appear black or grey in colour. [16] Under favourable conditions a zygosporangium forms, and the burst of the zygosporangium wall allows for the dispersal of spores. [13] In Mucor mucedo, sexual specificity can be observed between the two mating strains with the production of either 4-hydroxy methyltrisporates for (+) strains and trisporins for (-) strains. [21] These are ultimately converted to trisporic acids, the sexual hormone of M. mucedo and other zygomycetes, which induce the first steps of zygophore development on the opposite mating type. Trisporic acid is a volatile organic C18 compound that is made from β-carotene and retinol pathways, and 4-dihydromethyltrisporate dehydrogenase is found to be an important enzyme in the biosynthesis of trisporic acid. [22] [23]
Mucor mucedo is sensitive to the fungicide captafol (terrazol) which inhibits the apical growth of hyphae and, at lower concentrations, promotes thickening of the fungal cell wall. [24] Terrazol, with its fungistatic effect, induces liberation in phospholipases within the mitochondria and other membranes, leading to a complete lysis of the mitochondria. [25] The only known antidote for the effect of terrazol is impure saccharose, which contains phospholipase inhibitors. The cell wall thickening appears to be a side effect of the lowered phosphorylating capability of the mitochondria. [25] Pentachloronitrobenzene (PCNB) causes lysis of the internal structure of the mitochondria in M. mucedo, and the observed effect differs from that of terrazol. PCNB increases the perinuclear space and the number of vacuoles in the cell, and a pathological thickening of the cell wall is also observed. [26] The cell wall thickening occurring in M. mucedo is induced by some fungicides, N2 atmosphere, and high concentrations of glucose in growth media. The appears to be similar to the changes observed when transforming from mycelial to yeast form in dimorphic fungi. [27]
Mucor mucedo has world-wide distribution, and are commonly discovered in Canary Is., Egypt, Great Britain, Ireland, Kenya, Netherlands, Australia, Sri Lanka, Ukraine, China, and Canada. [28] [29] [30] M. mucedo is easily found in dry horse dung around March and April and have the common habitat of soil, dung, water, nose effluent of cow, composted leaf litter, stored grains, and many plants and fruits, such as grapes and tomatoes. [28] [31] It interacts with some animals but are not frequent causative agents of disease, including horse, rabbits, mice, and rats. [32] M. mucedo grows well on cheese and produces the 'cat hair' defect, which is white mould forming on cheese with long, grey, hyphae, giving it the appearance of cat hair. [33]
Mucor mucedo has been found to degrade polycyclic aromatic hydrocarbons (PAHs), a common soil pollutant and contaminant causing high concern, as contamination continues to increase. The species are highly efficient in biodegrading residual PAH in the soil, significantly decreasing it in within 12 days of introduction. [34] [35] Exopolymeric substances (EPS) produced by the fungus, mainly composed of proteins, carbohydrates, and humic-like substances, are responsible for the degradation. [35]
Mucor mucedo produces oxalate, or oxalic acid, a simple dicarboxylic acid that is one of the terminal metabolic products of many fungi and plants. It is well known to be toxic to higher animals, including humans, due to its local corrosive effect and affinity for calcium ions, which oxalate reacts with to form water-insoluble calcium crystals. [36] Mucor mucedo also produces aflatoxins, which are known to cause liver cancer and other digestive, urinary, endocrine, haematopoetic, reproductive, and circulatory complications, although this requires further confirmatory studies as aflatoxins are mainly characteristic of Aspergillus species. [37] [38] The ability for mycotoxins to diffuse from the mycelium into the environment depends on its water solubility. Products with high water content, notably cheese and dough, allow significant diffusion of mycotoxins. Aflatoxins have been observed to diffuse into food products without extensive mycelial growth into the food. [39]
Mucor mucedo sometimes cause opportunistic and rapidly spreading infections called mucormycosis. Also referred to as zygomycosis, this necrotizing infection can be life-threatening in diabetic or immuno-suppressed/compromised patients. [40] Mucor mucedo can cause minor infections as well, as there have been reported cases of frequent vomiting and severe purging along with prostration following the consumption of cheese contaminated with M. mucedo mould growth. [41]
Amphotericin B, a drug primarily used for treatment of patients with progressive and potentially life-threatening fungal infections, has been found to be a potent inhibitor of M. mucedo at concentrations of the drug ranging from 0.03 to 1.0 mcg/mL in vitro. [42] Amphotericin B functions by binding to sterols in the cell membrane of fungi leading to change in membrane permeability allowing leakage of intracellular components. [42]
Chitinases are hydrolytic enzymes that break down glycosidic bonds in chitin. They catalyse the following reaction:
Ascomycota is a phylum of the kingdom Fungi that, together with the Basidiomycota, forms the subkingdom Dikarya. Its members are commonly known as the sac fungi or ascomycetes. It is the largest phylum of Fungi, with over 64,000 species. The defining feature of this fungal group is the "ascus", a microscopic sexual structure in which nonmotile spores, called ascospores, are formed. However, some species of Ascomycota are asexual and thus do not form asci or ascospores. Familiar examples of sac fungi include morels, truffles, brewers' and bakers' yeast, dead man's fingers, and cup fungi. The fungal symbionts in the majority of lichens such as Cladonia belong to the Ascomycota.
A mold or mould is one of the structures that certain fungi can form. The dust-like, colored appearance of molds is due to the formation of spores containing fungal secondary metabolites. The spores are the dispersal units of the fungi. Not all fungi form molds. Some fungi form mushrooms; others grow as single cells and are called microfungi.
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.
Zygomycota, or zygote fungi, is a former division or phylum of the kingdom Fungi. The members are now part of two phyla: the Mucoromycota and Zoopagomycota. Approximately 1060 species are known. They are mostly terrestrial in habitat, living in soil or on decaying plant or animal material. Some are parasites of plants, insects, and small animals, while others form symbiotic relationships with plants. Zygomycete hyphae may be coenocytic, forming septa only where gametes are formed or to wall off dead hyphae. Zygomycota is no longer recognised as it was not believed to be truly monophyletic.
Aspergillus flavus is a saprotrophic and pathogenic fungus with a cosmopolitan distribution. It is best known for its colonization of cereal grains, legumes, and tree nuts. Postharvest rot typically develops during harvest, storage, and/or transit. Its specific name flavus derives from the Latin meaning yellow, a reference to the frequently observed colour of the spores. A. flavus infections can occur while hosts are still in the field (preharvest), but often show no symptoms (dormancy) until postharvest storage or transport.
The Mucorales is the largest and best-studied order of zygomycete fungi. Members of this order are sometimes called pin molds. The term mucormycosis is now preferred for infections caused by molds belonging to the order Mucorales.
Mucor is a microbial genus of approximately 40 species of molds in the family Mucoraceae. Species are commonly found in soil, digestive systems, plant surfaces, some cheeses like Tomme de Savoie, rotten vegetable matter and iron oxide residue in the biosorption process.
Candex is a dietary supplement manufactured by Pure Essence Laboratories. It is marketed as an enzymatic remedy to treat the yeast infection candida. Having the status of a dietary supplement, its efficiency has not been proven in scientifically controlled and peer-reviewed trials. Similar formulas exist, such as Candigest.
Mucor racemosus is a rapidly growing, weedy mould belonging to the division Mucoromycota. It is one of the earliest fungi to be grown in pure culture and was first isolated in 1886. It has a worldwide distribution and colonizes many habitats such as vegetational products, soil and houses. The fungus is mostly known for its ability to exhibit both filamentous and yeast-like morphologies, often referred to as dimorphism. Stark differences are seen in both forms and conditions of the environment heavily affect the phases of the M. racemosus. Like many fungi, it also reproduces both sexually and asexually. The dimorphic capacity of this species has been proposed as an important factor in its pathogenicity and has enhanced the industrial importance. This species is considered an opportunistic pathogen, generally limited to immunocompromised individuals. It has also been associated with allergy and inflammations of facial sinuses. Its association with allergy has made it a common fungus used in allergen medical testing. Industrial use of the fungus is in the production of enzymes and the manufacture of certain dairy foods.
Plasmopara viticola, the causal agent of grapevine downy mildew, is a heterothallic oomycete that overwinters as oospores in leaf litter and soil. In the spring, oospores germinate to produce macrosporangia, which under wet condition release zoospores. Zoospores are splashed by rain into the canopy, where they swim to and infect through stomata. After 7–10 days, yellow lesions appear on foliage. During favorable weather the lesions sporulate and new secondary infections occur.
A fungus 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 one of the traditional eukaryotic kingdoms, along with Animalia, Plantae, and either Protista or Protozoa and Chromista.
Spinellus fusiger, commonly known as bonnet mold, is a species of fungus in the phylum Mucoromycota. It is a pin mold that is characterized by erect sporangiophores that are simple in structure, brown or yellowish-brown in color, and with branched aerial filaments that bear the zygospores. It grows as a parasitic mold on mushrooms, including several species from the genera Mycena, including M. haematopus, M. pura, M. epipterygia, M. leptocephala, and various Collybia species, such as C. alkalivirens, C. luteifolia, C. dryophila, and C. butyracea. It has also been found growing on agaric species in Amanita, Gymnopus, and Hygrophorus.
Mucor plumbeus is a fungus in the family Mucoraceae that is very common, abundant and distributed worldwide. Mucor plumbeus is not known to be a plant or animal pathogen; however it is able to elicit an immune response in humans by activating the complement system. This species is commonly found in various types of soils over a range of pH, although alkaline soils seem more conducive to its growth. It is also known from the roots of wheat, oat and barley. In addition, M. plumbeus is a common fungal contaminant of indoor built environments. This species shares many similarities with M. racemosus, another fungus that belongs to the family Mucoraceae which is known to cause mucormycosis. Mucor plumbeus is a common spoilage agent of cheese, apples, apple cider and yogurt.
Rhizopus oryzae is a filamentous heterothallic microfungus that occurs as a saprotroph in soil, dung, and rotting vegetation. This species is very similar to Rhizopus stolonifer, but it can be distinguished by its smaller sporangia and air-dispersed sporangiospores. It differs from R. oligosporus and R. microsporus by its larger columellae and sporangiospores. The many strains of R. oryzae produce a wide range of enzymes such as carbohydrate digesting enzymes and polymers along with a number of organic acids, ethanol and esters giving it useful properties within the food industries, bio-diesel production, and pharmaceutical industries. It is also an opportunistic pathogen of humans causing mucormycosis.
Rhizopus stolonifer is commonly known as black bread mold. It is a member of Zygomycota and considered the most important species in the genus Rhizopus. It is one of the most common fungi in the world and has a global distribution although it is most commonly found in tropical and subtropical regions. It is a common agent of decomposition of stored foods. Like other members of the genus Rhizopus, R. stolonifer grows rapidly, mostly in indoor environments.
Mucor circinelloides is a dimorphic fungus belonging to the Order Mucorales. It has a worldwide distribution, found mostly in soil, dung and root vegetables. This species is described as not known to be able to produce mycotoxins, however it has been frequently reported to infect animals such as cattle and swine, as well as fowl, platypus and occasionally humans. Ketoacidotic patients are particularly at risk for infection by M. circinelloides.
Mortierella polycephala is a saprotrophic fungus with a wide geographical distribution occurring in many different habitats from soil and plants to salt marshes and slate slopes. It is the type species of the genus Mortierella, and was first described in 1863 by Henri Coemans. A characteristic feature of the fungus is the presence of stylospores, which are aerial, spiny resting spores (chlamydospores).
Mucoromycota is a division within the kingdom fungi. It includes a diverse group of various molds, including the common bread molds Mucor and Rhizopus. It is a sister phylum to Dikarya.
Actinomucor elegans was originally described by Schostakowitsch in Siberia in 1898 and reevaluated by Benjamin and Hesseltine in 1957. Commonly found in soil and used for the commercial production of tofu and other products made by soy fermentation. Its major identifying features are its spine-like projections on the sporangiophore and its ribbon-like hyphal structure when found in the tissue of a host.
mucor mucedo.