Aspergillus flavus is composed of two morphotypes designated as l, for large sclerotia, or s, for small sclerotia cotty, 1989. The colour of the colonies was used for first identification of the sections. The fungus is also an opportunistic animal and human pathogen causing aspergillosis diseases with incidence increasing in the immunocompromised population. Identification key for aspergillus species isolated from. In addition to causing preharvest and postharvest infections, many strains produce toxic compounds known as mycotoxins. Table 1 summarises the morphological differences between the two species. Aspergilli have great importance in many fields like plant, animals, and human health etc. The present study was conducted to identify aspergillus isolates from district larkana sindh pakistan. A family of toxins produced by fungi such as aspergillus flavus. Aspergillus flavus has a worldwide distribution and normally occurs as a saprophyte in soil and on many kinds of decaying organic matter, however, it is also a recognised pathogen of humans and animals. With dna evidence, all members of the genus aspergillus are members of the ascomycota. Sexual reproduction in aspergillus flavus sclerotia. It has attained a high level of agricultural significance due to production of the carcino.
Aspergillus sections nigri were identified by the colonies in shades of black and brown. Other articles where aspergillus flavus is discussed. Aspergillus flavus is unique in that it is a thermotolerant fungus, so can survive at temperatures that other fungi cannot. Aspergillus flavus is the principal aflatoxinproducing species only group.
This species is known primarily for its ability to produce a potent toxin and carcinogen known as aflatoxin 1. Aspergillus section flavi historically includes species with conidial heads in shades of yellowgreen to brown and dark sclerotia. Aflatoxin b1 is the most common form and is also the most potent aflatoxin and carcinogen. Aspergillus flavus an overview sciencedirect topics. The fungus aspergillus flavus is the most important source of aflatoxins. Morphological characteristics of aspergillus species. Identification and characterization of aspergillus flavus and. Aspergillus flavus populations in surface 5cm depth soil, sampled before planting marchapril, midseason june and after harvest september, ranged from 1. Isolation and identification of aspergillus flavus from poultry feed samples using combined traditionalmolecular approach.
The ubiquitous fungus aspergillus is especially prevalent in the air. It also grows on cereal grains, legumes, and tree nuts. Aspergillus flavus aspergillus flavus produces the carcinogenic mycotoxin, aflatoxin which often contaminates foods such as nuts. Yet, it also possesses the characteristics of an opportunistic pathogen with a wide, nonspecific host range plants, animals, and insects. Pdf this chapter presents aspects involving fungi of the genus aspergillus in agroecology.
In certain locales and hospitals, aspergillus flavus is more common in air than a. Doc aspergillus flavus griya agroforestry academia. These characteristics its potential use in alkaline. Abstract aspergillus flavus is a fungus that principally obtains resources for growth in a saprophytic mode. Khoa hoc ky thuat thu y veterinary sciences and techniques, 72. The isolation of the species of the nigri section on creatine sucrose agar crea enabled to distinguish the aspergillus sp species, which was characterized by the lack of sporulation and by the. Pdf identification and characterization of aspergillus flavus and. In both grains and legumes, infection is minimized to small areas, and discoloration and dullness of affected areas is often seen. It is a fungus with a very widespread distribution. This strain has been shown to produce a consistently high. Abstract aspergillus is a large genus of anamorphic fungi.
A network of hyphae known as the mycelium secretes enzymes that break down complex food sources. Pdf isolation and identification of aspergillus flavus. Yellow green, green, deep green co lours were either for sections fumigatiflavi or, nidulantes. Aspergillus flavus is saprophytic soil fungus that infects and contaminates preharvest and postharvest seed crops with the carcinogenic secondary metabolite aflatoxin. Accurate species identification within aspergillus flavus complex remains difficult due to overlapping morphological and biochemical. Aspergillus parasiticus is found commonly on peanuts. Aspergillus flavus colonizes agricultural commodities worldwide and contaminates them with carcinogenic aflatoxins. The growth and aflatoxin production of aspergillus flavus strains on. Aspergillus flavus simple english wikipedia, the free. Aspergillus infections have grown in importance in the last years. This strain has been shown to produce a consistently high content of aflatoxin that affects crops and animals alike. It is a causative agent of otitis, keratitis, acute and chronic invasive sinusitis, and pulmonary and systemic infections in immunocompromised patients. Aspergillus flavus is a potentially dangerous pathogen. After aspergillus fumigatus, aspergillus flavus is the second most common aspergillus mold to infect humans.
Due to the fact that it breaks down cellulose and lignin, the fungus has a special ecological value. Aspergillus fungi definition, characteristics, types and. Exposure to aspergillus flavus af36 via drinking water from all uses of aspergillus flavus af36 is not likely to be greater than currentexisting exposures to aspergillus flavus strains, which are already present in the environment. Such is the case with aspergillus flavus, perhaps the most significant fungal species from an agricultural standpoint. They were identified through the examination of their morphological features as per the key descriptions recommended by klich 8 and clayton 15. 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. Aspergillosis is a large spectrum of fungal diseases, which primarily affect the lungs and are caused by members of the genus aspergillus. Aspergillus flavus and the closely related subspecies parasiticus have long been recognized as major contaminants of organic and nonorganic items.
To confirm apergillus section flavi by colony reverse colour the isolates were subcultured and transferred to aspergillus flavus parasiticus agar afpa as described by, and incubated in the dark at 2818 c for. It grows by producing thread like branching filaments known as hyphae. Identification of fungi of the genus aspergillus hydrolytic enzymes like lipases and amylases 1, 26. However, most of the studies have focused on aspergillus fumigatus, the most prevalent species in the genus.
The surface of aspergillus flavus is yellowgreen in color and it is gold or red brown underneath. Potential risks via exposure to drinking water or runoff may be mitigated by, among other things, percolation. Identification and characterization of aspergillus flavus and aflatoxins. Aspergillus flavus center for integrated fungal research. Aspergillus flavus is a pathogenic fungus in the phylum ascomycota.
Aspergillus is the name used for a genus of moulds that reproduce only by asexual means. Aspergillus flavus definition of aspergillus flavus by. Aspergillus flavus colonies are commonly powdery masses of yellowishgreen spores on the upper surface and reddishgold on the lower surface. Attachment ifinal risk assessment of aspergillus oryzae february 1997 i.
Identification of aspergillus flavus isolates fortythree a. The size and arrangement of the conidial heads as well as the colour of the spores they bear are important identifying characteristics. Chandrasekar1 1division of infectious diseases and 2department of internal medicine, wayne state university, john d. The presence of this fungus and aflatoxins is of huge concern. Aspergillus is defined as a group of conidial fungithat is, fungi in an asexual state. Accurate species identification within aspergillus flavus complex remains difficult due to overlapping morphological and biochemical characteristics, and much taxonomic and population genetics work is necessary to better understand the species and related species. Nov 20, 2019 ket qua nghien cuu su co mat cua aspergillus flavus o dat trong ngo, than, be va bap ngo truoc va trong thu hoach. Aspergillus sp ufla dca 01, despite not having been totally effective in elucidating species related to a. Aspergillus flavus is distinguished by rapid growth at both 25c and 37c, and a bright yellow green or less commonly yellow conidial colour. The alkalophillic isolate aspergillus flavus shows maximum alkaline protease enzyme activity was 2000 uml at ph 8.
Pdf aspergillus flavus is the main producer of the well known carcinogenic aflatoxins. As with fungi in general, aspergillus taxonomy is complex and ever evolving. Aspergillus flavus is saprophytic soil fungus that infects and contaminates. Sometimes, in certain circumstances, it can become an optional parasite organism for plants, animals or humans. The physicochemical characteristics of cheese are subject to changes during ripening, which influence the mycotoxin production. Morphological characterization and determination of aflatoxin. Aflatoxins are usually elaborated during storage of funguscontaminated feed, particularly in humid conditions, and may be present in many crops, including corn, peanuts, and co. The genus is easily identified by its characteristic conidiophore, but species. Aspergillus, genus of fungi in the order eurotiales phylum ascomycota, kingdom fungi that exists as asexual forms or anamorphs and is pathogenic diseasecausing in humans. Introduction aspergillus oryzae is an asexual, ascomycetous fungus used for hundreds of years in the production of soy sauce, miso and sake without recorded incidents.
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