What is Aspergillus?
Aspergillus (Plural Aspergilli) is a genus offungi that consists of about 300 identified species of mold (mould).Aspergillus can be found in a variety of environments throughout the worldgiven that their growth is largely determined by the availability of water.
The rate at which they grow is largely determined by the temperaturerange in the environment they grow in. Regardless, studies have shownAspergillus to be able to tolerate extreme conditions only if all of theother conditions are ideal.
Given that a majority reproduce asexually, they are often described as conidial fungi. However, studies are yetto determine how a good number of others reproduce while some havebeen shown to reproduce sexually.
A majority have been shown to be terricolous, which means that they are largely found in soil/land. Since their discovery in the 1720s, they have become increasingly important in human health, agriculture as well as in biological sciences among others.
*conidial fungi are fungi that reproduce asexually through the production of spores from the fungi hyphae. The spore produced is referred to as conidium.
General Characteristics of Aspergillus
Aspergilli can be found throughout nature withtheir spores being abundant in air. In addition to largely being saprophytesthat obtain their nutrition from dead and decaying matter, they can also bepathogenic to human beings and animals with some also affecting and damagingplants.
Because they lack chlorophyll, and aretherefore unable to produce their own food, they are dependent on othermaterial in their surroundings for nutrition. Here, it's worth noting thatAspergilli are incapable of absorbing organic matter in their surroundings.
For this reason, they release different types of enzymes such asamylase capable of breaking down these materials intosimpler compounds that can be absorbed through the vegetative hyphae.
Therelease of high amounts of these enzymes results in enhanced decay of allorganic matter in their immediate environment and consequently the availabilityof more food source necessary for reproduction and growth.
For most part, they reproduce asexuallythrough the production of spores known as conidium (fungi spore). Once thespore lands on a favorable environment (with moisture, warmth and nutrients)they start germinating where they create numerous hyphae that form the mycelium.
The hyphae allows them to grow, spread and continue reproducingacross the surface of the substrate.
The life cycle ofAspergillus may therefore be summarized as follows:
Life Cycle of Aspergillus
* Aspergilli's hyphae develops into vegetativeand reproductive hyphae. The vegetative hyphae serves to absorb nutrients whilethe reproductive hyphae develop further to produce spores.
Types of Aspergillus
There are several types of species that fallunder the genus Aspergillus.
The following are some of the most common fungithat belong to this genus:
Aspergillus Niger - CDC photo credit: Ginger Chew, ScD
Aspergillus niger largely exist as saprophytes,which means that they obtain their nutrition from a variety of dead anddecaying material such as leaves, fruits and other vegetation. As such, theyalso contribute to the delay of various food products. given that their sourceof vegetation are readily available virtually everywhere.
A. niger arewidely distributed and common in many geographical areas. However, they are known to be particularly prevalent in areas with higher temperatures.
* Research has show that the black spores ofA. niger help protect them from the sun's radiation, which in turnallows this species to thrive in warm areas.
Morphology of Aspergillus Niger
Like others, Aspergillus nigerare filamentous fungi, which means that they tend to form filaments (hyphae)and thus resemble the structure of a plant. When viewed under the microscope,A. niger consists of a smooth and colorless conidiophores and spores.
A closer look will reveal the conidial heads of the organism to be globose anddark brown in color that have been shown to divide into a number of columns asthe A. niger continues to age.
Compared to the other types, A. niger produces dark or dark brown spores from theirconidial heads (biserite). This is a characteristic that has only been seen onA. niger and none of the others.
* In microscopy, the carbon black/dark browncolor of the spores (as well as the conidia) is used to distinguish A. niger from other species in the same genus.
Aspergillus niger is an ascomycetous fungus.This means that it is classified under the phylum Ascomycota, also commonly referredto as Sac Fungi. As such, spores are produced within the sacs (Asci)(asexually).
Like Aspergillus nidulans, colonies of A. niger that havebeen exposed to air (in suitable conditions for growth) tend to form vegetativeand reproductive hyphae. Whereas the vegetative hyphae absorb nutrients fromthe dead and decaying matter, the spores (conidium) are produced from the tipof the reproductive hyphae (that looks like a vesicle).
Aspergillus Flavus - Public Domain
Like A. niger, Aspergillus flavus aresaprophytes that can be found in soil samples where they obtain their nutritionfrom dead and decaying matter. In particular, A. flavus are a nuisanceto farmers given that they tend to infect and contaminate crops (seeds).
A. flavus are divided into two majorgroups based on their morphology.
S Strain- The S strain of Aspergillus flavus,also referred to as Group I strain has a sclerotia (hardened mass of mycelium)that is less than 400 mm in size, which is its defining characteristic. Thisstrain has been shown to produce a consistently high content of aflatoxin thataffects crops and animals alike.
L Strain - Compared to the S strains, the Lstrain of Aspergillus flavus has a sclerotia that is larger than 400 mm indiameter. While this strain also produces aflatoxins, the amount produced varyfrom high to low and thus not consistent as is the case with the S strain.
* In human beings, aflatoxins produced byAspergillus tend to cause serious intestinal problems as well as liver cancers.
* A. flavus is the second leading causeof Aspergillosis among patients with weak immunity. This is an infection of thelungs by the fungi (fungi balls)
Like other types, theA. flavus also produces hyphae, this includes the vegetative andreproductive hyphae. In the vegetative hyphae (mycelium) A. flavus producesenzymes that are responsible for the breakdown of food material into simplerforms that can be absorbed.
While the organism has been shown to produce spores (conidiospores) asexually, studies have shown the genetic diversity ofthis species to be as a result of sexual reproduction where ascospores areproduced within the sclerotia of A. flavus.
* ascospore - spores that are produced in theascus
Morphology of Aspergillus Flavus
Some of the main parts of the A. flavusmorphology include:
- The stipe
When viewed under the microscope, A. flavusappear to have radiating conidial heads while the conidiophores will appearrough.
Aspergillus Fumigatus By Dr. David Midgley [CC BY-SA 2.5 (https://creativecommons.org/licenses/by-sa/2.5)], via Wikimedia Commons
Aspergillus fumigatus is one of the most prevalentAspergillus found in most environments. One of the most unique characteristicsthat separates A. fumigatus from the rest of the Aspergillus is that it cansurvive very high temperatures (it's thermotolerant) which is one of thereasons as to why it is more prevalent.
A. fumigatus also exists as asaprophyte that plays an important role in the cycle of carbon and nitrogen innature. Because it is very prevalent, the spores of A. fumigatus arealso in high concentration in air, which presents a serious health issues forthose with poor immunity.
Compared to other species in this genus, A. fumigatus has been shown to be the leading infectious pathogen among those withcompromised immunity.
* The fungi can survive at 37 degree Celsius whilethe conidia can survive temperatures of up to 70 degree Celsius.
Aspergillus fumigatus is a filamentous fungithat uses both sexual and asexual means of reproduction. However, the sexualmeans of reproduction are yet to be understood.
In asexual reproduction,conidia are produced through mitotic division. Here, mitotic division takeplace within the conidophore vesicle and are released by any disturbance of theimmediate environment.
This causes the spores to be in high concentration inair where they can be easily inhaled (causing health problems for those withcompromised immunity) - asexual reproduction in Aspergillus fumigatus takesplace when the mycelia does not interact with other haploid mycelia.
When the mycelia comes in contact with thehyploid mycelia, then sexual reproduction occurs. According to studies, thismeans of reproduction in A. fumigatus often occurs when there is a low supplyof nutrients particularly when the growing season comes to the end. This istherefore a beneficial means of production in that it allows the A. fumigatusto continue reproducing in unfavorable conditions.
Here, the haploid hyphaecome in contact allowing their nuclei to fuse. This is then followed by meioticdivision of the diploid ascus to form ascospores (four of them) that are thenreleased in air to continue the cycle.
Morphology of Aspergillus Fumigatus
The following are some of the morphological characteristics of Aspergillus Fumigatus:
- They produce spores of between 200 and 400 mm
- The color of the stipes is gray around the apex
- They have a smooth surface
- They have a small, columnous globuse
- The surface of the conidia is either smooth or spinose
Aspergillus Nidulans By Plasmidmap [CC BY 3.0 (https://creativecommons.org/licenses/by/3.0)], via Wikimedia Commons
Aspergillus nidulans (Emericella nidulans) isalso one of the most studied Aspergillus. One of the main reasons as to why ithas become one of the most studied fungi is because it has been found to bevery closely related to a majority of other species of Aspergillus in additionto a well organized genetic system. As such, it has proved to be particularlyimportant in medical and industrial research.
While it is the subject of manyresearch studies, the means of reproduction of A. nidulans is yet tobe well understood. However, a number of studies have shown the organism to useboth the sexual and asexual means.
Unlike the others that cause foodspoilage by enhancing decay, Emericella nidulans does not necessary cause such spoilage.It can grow at relatively high temperatures and has been shown to produce atoxin (mycotoxin) that can result in health complications among those withcompromised immunity.
Importance of Aspergillus
- Carbon and nitrogen cycle - In response to its need for nutrition, studies have shown A. fumigatus to beable to sense the presence of nitrogen and carbon material resulting in theAspergillus breaking down this material (particularly non-woody plants) toobtain nutrients and for absorption. This has been shown to be an important process in the cycle ofcarbon and nitrogen in nature.
- Enzymes - Aspergillusobtain their nutrients by releasing enzymes that break down food material intosmaller constituents that can be easily absorbed. This mechanism has provedparticularly beneficial in various industries where these organisms are being usedfor their enzymes to break down various proteins and other compounds. One ofthe most commonly used organism is A. oryzae, which is largely used forfermentation of various products.
Some of the other important uses of Aspergillusinclude:
- Food preservation - Due toits capacity to decompose, A. niger is used to preserve various food productsfrom spoilage
- Citric acid - A. niger isused in industry to produce citric acid
While Aspergillus have a number of benefits,they have various disadvantages that include:
Food spoilage - Aflatoxins produced by some spoil various crop seeds. These toxins are dangerous and can causeserious health issues and even death when consumed. On the other hand, enzymesproduced by Aspergillus enhance the decay of fruits and other foods.
Human and animal infections - Aflatoxins,Aspergillus and their spores can have negative health consequences wheninhaled. Whereas aflatoxins can affect both healthy and unhealthy animals andhumans, Aspergillus and their spores can have grave negative consequences onthe health of those with poor immunity.
Read more about Mycelium in Fungi here
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FengfengWang. Inhibition of secretion by asexual reproduction in Aspergillus niger.2014.
NancyKeller. Aspergillus flavus.September 2011.
Tobias MHohl. Aspergillus fumigatus: Principles of Pathogenesis and Host Defense.ArticleinEukaryotic Cell · December 2007.
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How do you identify Aspergillus flavus? ›
Aspergillus flavus is a mycotoxigenic fungus that possesses the ability to produce B aflatoxins. It can be readily distinguished morphologically by the production of a bright yellow-green conidial color, when cultured on malt extract agar or Czapek yeast extract agar.What is Aspergillus classification and identification? ›
Aspergillus is defined as a group of conidial fungi—that is, fungi in an asexual state. Some of them, however, are known to have a teleomorph (sexual state) in the Ascomycota. With DNA evidence, all members of the genus Aspergillus are members of the phylum Ascomycota.What is the identification of Aspergillus? ›
Microscopic characteristics for the identification were conidial heads, stipes, color and length vesicles shape and seriation, metula covering, conidia size, shape and roughness also colony features including diameter after 7 days, color of conidia, mycelia, exudates and reverse, colony texture and shape.What are the common types of Aspergillus? ›
Aspergillus fumigatus is the most common cause of human Aspergillus infections. Other common species include A. flavus, A. terreus, and A.What are the characteristics of Aspergillus niger? ›
Cultural Characteristics of Aspergillus niger
Generally, they have a cottony appearance; initially white to yellow and then turning black. Made up of felt-like conidiophores. The reverse is white to yellow. In microscopy, the conidial heads are radiate with conidiogenous cells biseriate.
The microscopic characteristics of Aspergillus flavus isolate 5 under the basic biological light microscope showing the biseriate with philiades radiating from all sides (a); the globose conidia with varying sizes that are slightly roughened (b); and unbranched conidiophore which is nonseptate, rough, and hyaline (c).What are the 4 classifications of fungal infections? ›
When classified according to the site of infection, fungal infections are designated as superficial, cutaneous, subcutaneous, and deep (Fig. 75-1).What disease does Aspergillus cause? ›
Aspergillosis is an infection caused by Aspergillus, a common mold (a type of fungus) that lives indoors and outdoors. Most people breathe in Aspergillus spores every day without getting sick.What are the three types of aspergillosis? ›
However, some types can cause a variety of diseases in humans ranging from simple allergic reactions to life-threatening invasive disease. Collectively, this group of diseases is referred to as aspergillosis and is broadly broken down into three categories – allergic, chronic and invasive.What is the common method used in identification of fungi? ›
Diagnosis of fungal infection has relied primarily on methods such as direct microscopic examination of clinical samples, histopathology, and culture. Such approaches are dependent on personnel with relatively high levels of specific mycology training.
Which method is used for fungal identification? ›
There are two distinct approaches to genotypic identification of fungi: sequencing of the D2 region of the large subunit ribosomal DNA (D2 LSU), and sequencing of either one or both of the internal transcribed spacer regions between the small and large subunit ribosomal RNA genes (ITS).What is the difference between Aspergillus flavus and fumigatus? ›
Although belong to the same genus, Aspergillus fumigatus is primarily involved in invasive pulmonary infection, whereas Aspergillus flavus is a common cause of superficial infection.What is the most common cause of aspergillosis? ›
Aspergillosis is an infection caused by a type of mold (fungus). The illnesses resulting from aspergillosis infection usually affect the respiratory system, but their signs and severity vary greatly. The mold that triggers the illnesses, aspergillus, is everywhere — indoors and outdoors.Where is Aspergillus most common? ›
Aspergillosis is caused by a fungus called aspergillus. The fungus is often found growing on dead leaves, stored grain, compost piles, or in other decaying vegetation. It can also be found on marijuana leaves.Is Aspergillus niger black mold? ›
Black mould, caused by Aspergillus niger, is the main fungal disease affecting date fruits. Symptoms develop inside the fruit, at the inner space between the pulp and the seed.How would you describe Aspergillus under a microscope? ›
The microscopic features included uniseriate aspergilli, columnar conidial heads, flask-shaped vesicles with the phialides covering one half to three quarters of the vesicle, and globose conidia that were finely rough and plain green in color [19, 20].How do you see Aspergillus under a microscope? ›
Microscopy. Microscopic methods, such as wet mounts, Gram stains, and conventional histopathology, provide clues that suggest the presence of Aspergillus spp. in tissue. Blankophor or Calcofluor mixed with 10%–20% potassium hydroxide (KOH), stains fungal cell walls and improves detection of fungi.What does Aspergillus niger look like under a microscope? ›
When viewed under the microscope, A. niger consists of a smooth and colorless conidiophores and spores. A closer look will reveal the conidial heads of the organism to be globose and dark brown in color that have been shown to divide into a number of columns as the A. niger continues to age.How do you get rid of fungus in your body? ›
- Antifungal creams, many of which are available over-the-counter.
- Stronger prescription medications, which may work faster.
- Oral medicines, if the fungal infection is severe.
Invasive candidiasis is an infection caused by a yeast (a type of fungus) called Candida. Unlike Candida infections in the mouth and throat (also called “thrush”) or vaginal “yeast infections,” invasive candidiasis is a serious infection that can affect the blood, heart, brain, eyes, bones, and other parts of the body.
What is the most serious fungal infection? ›
The most dangerous is the "critical group," which contains just four fungal pathogens: Cryptococcus neoformans, Aspergillus fumigatus, Candida albicans and Candida auris.How do you get rid of Aspergillus in your body? ›
These drugs are the standard treatment for invasive pulmonary aspergillosis. The most effective treatment is a newer antifungal drug, voriconazole (Vfend). Amphotericin B is another option.
Triazole antifungal drugs, commonly called azoles, are the primary treatment for aspergillosis.
Aspergillus species are filamentous fungi that are commonly found in soil, decaying vegetation, and seeds and grains, where they thrive as saprophytes. Aspergillus species can be occasionally harmful to humans [1-3].What is a rare fungal infection in the lungs? ›
Blastomycosis is an uncommon, but potentially serious fungal infection. It primarily affects the lungs, and is caused by the fungus Blastomyces dermatitidis. The signs and symptoms of illness that can result from exposure to this soil organism are variable.How many species of Aspergillus are there? ›
Aspergillus is a very large genus containing more than 185 species to which human are contantly exposed, only very few of them are responsible for disease. Approximately, 95% of the disease encountered by three species namely Aspergillus fumigatus, Aspergillus niger and Aspergillus flavus.Who is the most common victim of aspergillosis? ›
Allergic bronchopulmonary aspergillosis (ABPA) most often occurs in people who have cystic fibrosis or asthma. Aspergillomas usually affect people who have other lung diseases like tuberculosis. Also called a “fungus ball.”What are the 3 methods of identification useful to identify bacteria? ›
- Identifying Microbes Using PCR. PCR, including Real-Time PCR, is probably the most widely used molecular technique for identifying microbes. ...
- Microarray-Based Identification. ...
- Immunological Identification. ...
- Chemical/Analytical Identification.
The most common technique is conventional PCR, while other recent techniques include nested PCR, to obviate low levels of target pathogens, multiplex PCR, to detect several pathogens simultaneously, real-time PCR, to quantify fungi on seeds, and magnetic-capture hybridization PCR.Which test is most suitable for the identification of a fungal infection? ›
A fungal culture test is used to find out whether you have a fungal infection. The test may help identify the type of fungus that you have. The test is also used to help guide treatment and to see if treatment is working.
Which gene is most useful for identification of fungal species? ›
The gene regions RPB1, RPB2, tub2/BenA, and partial calmodulin (CaM) are useful for species-level identification in certain lineages of fungi such as Eurotiales, which includes Aspergillus and Penicillium, two of the most prolific genera of fungi for secondary metabolites and which include numerous medicinally and ...What is used to identify dermatophyte fungi? ›
Dermatophyte infections can be readily diagnosed based on the history, physical examination, and potassium hydroxide (KOH) microscopy. Diagnosis occasionally requires Wood's lamp examination and fungal culture or histologic examination.Which medium is used for the identification of dermatophyte fungus? ›
The identification of dermatophytes was performed through microscopic examination using 10% potassium hydroxide (KOH) with 40% dimethyl sulphoxide (DMSO) mounts and culture on Sabouraud dextrose agar (SDA) and on Dermasel agar base media, both supplemented with chloramphenicol and cycloheximide.What are the 3 ways to classify fungi? ›
- Molds: They are multicellular and filamentous. Example: Fusarium sp.
- Mushroom: These are macroscopic filamentous fungi that bear large fruiting bodies. Example: Polyporus squamosus.
- Yeast: They are single-celled microscopic fungi. Example: Saccharomyces sp.
The kingdom Fungi contains five major phyla: Chytridiomycota, Zygomycota, Ascomycota, Basidiomycota, and Glomeromycota.What are the 7 levels of classification for fungi? ›
The true fungi, which make up the monophyletic clade called kingdom Fungi, comprise seven phyla: Chytridiomycota, Blastocladiomycota, Neocallimastigomycota, Microsporidia, Glomeromycota, Ascomycota, and Basidiomycota (the latter two being combined in the subkingdom Dikarya).What is the main classification of fungi? ›
Fungi are usually classified in four divisions: the Chytridiomycota (chytrids), Zygomycota (bread molds), Ascomycota (yeasts and sac fungi), and the Basidiomycota (club fungi). Placement into a division is based on the way in which the fungus reproduces sexually.What is fungi in classification? ›
Fungi are eukaryotic organisms that include microorganisms such as yeasts, moulds and mushrooms. These organisms are classified under kingdom fungi. The organisms found in Kingdom fungi contain a cell wall and are omnipresent.What are the classification criteria of fungi? ›
The classification of fungi relies mostly on morphological criteria such as the pigmentation, shape of hyphae, presence or absence of septa and types of spores. The taxonomy of mould and yeasts is governed by International Code of Botanical Nomenclature (ICBN).What is identification of fungi? ›
DETERMINING THE TAXONOMICAL GROUP OF FUNGI THROUGH DNA SEQUENCING. The IDENTIFICA fungi ID service will identify the fungi species in your sample. Accurate fungi identification is essential for disease diagnosis, criminal investigations, environmental studies, food quality control, etc.
What are the 3 major types of fungi? ›
- Multicellular filamentous moulds.
- Macroscopic filamentous fungi that form large fruiting bodies. ...
- Single celled microscopic yeasts.
The kingdom Fungi contains five major phyla: Chytridiomycota, Zygomycota, Ascomycota, Basidiomycota, and Glomeromycota.What are the 7 classification of fungi? ›
The true fungi, which make up the monophyletic clade called kingdom Fungi, comprise seven phyla: Chytridiomycota, Blastocladiomycota, Neocallimastigomycota, Microsporidia, Glomeromycota, Ascomycota, and Basidiomycota (the latter two being combined in the subkingdom Dikarya).Is mold a type of fungus? ›
Mold is a fungal growth that forms and spreads on various kinds of damp or decaying organic matter. There are many different mold species that come in many different colors. Molds are sometimes referred to as mildew. They are found both indoors and outdoors in all climates, during all seasons of the year.Does skin fungus itch? ›
Fungal skin infections can be itchy and annoying, but they're rarely serious. Common infections such as athlete's foot, jock itch, and ringworm are caused by fungus and are easy to get and to pass around. In healthy people, they usually don't spread beyond the skin's surface, so they're easy to treat.Is A fungus a bacteria? ›
Fungi are yet another form of life different from viruses or bacteria. Like animals or plants, they belong to the so-called eukaryotes. These are living organisms whose cells have a nucleus and a rich compartmentalisation.What are the 8 levels of classification for a mushroom? ›
- Classification Order:
- Domain: Eukarya.
- Super-group: Opisthokonta.
- Kingdom: Fungi.
- Phylum: Basidiomycota.
- Class: Agaricomycetes.
- Order: Agaricales.
- Family: Agaricaceae.
The main criteria for classifying organism into five kingdoms are the complexity of cells structure, body organization, the mode of nutrition, life style, and phylogenetic relationship. This system consists Monera, Protista, Fungi, Plantae, and Animalia.What are the 4 approaches to laboratory diagnosis of fungi? ›
Traditional approaches to diagnosis include direct microscopic examination of clinical samples, histopathology, culture, and serology.Why is it important to identify unknown fungi? ›
Members of the fungal kingdom play significant roles in human life and have the ability to occupy a wide variety of natural and artificial niches. Identification of fungi to species level is paramount in both basic (ecology, taxonomy) and applied (genomics, bioprospecting) applications in scientific research.
What are 6 characteristics of a fungus? ›
The traits highlighted here represent just a sample of the characteristics that have evolved in fungi, including polarized multicellular growth, fruiting body development, dimorphism, secondary metabolism, wood decay, and mycorrhizae.