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Microbiology 205 Georgetta Seidel.

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1 Microbiology 205 Georgetta Seidel

2 Definitions Mycologists--scientists who study fungi Mycology--scientific discipline dealing with fungi Mycoses--diseases caused in animals by fungi



5 The five kingdom system
Eukarya (includes all organism with a nucleus & membrane bound organelles) Plants and Animals are fairly obvious Fungi, are very distinct from the other kingdoms Kingdom Protista is a “dumping ground” for organisms that don’t fit into the other eukaryotic kingdoms


7 Exoenzymes are found in fungi and some bacteria
Exoenzymes are found in fungi and some bacteria. They are digestive enzymes that are secreted into the environment, where they digest the food into small molecules that can be absorbed and used by the fungus.


9 5,000 plant pathogens=$1 billion/yr
FUNGI 100,000 species 100 human pathogens, fungi associated diseases are rising, due to nosocomial infections and in immunocompromised patients (ie. HIV, diabetes, lupus, transplant folks) Aspergillosis, Blastomycosis—pulmonary infections and dissemination may be involved 5,000 plant pathogens=$1 billion/yr 2

10 IMPORTANCE OF FUNGI Fermentation industry
Remember fermentation is an anaerobic process Wine (yeast) Beer Bread Cheese (bacteria) Soy sauce (filamentous fungi (Aspergillus oryzae provides a low protein diet with amino acids, yeast & bacteria) soy beans & flour are held in a container for mold to grow—moldy beans are incubated for several months Sauerkraut Vinegar (yeast and bacteria) Yoghurt (Bacteria) 5

11 IMPORTANCE OF FUNGI Drug manufacturing (usually their waste products are to our benefit) Citric acid Ethanol (yeast) Antibiotic griseofulvin, penicillin Cortisone (Rhizopus) immunosuppressive agents (cyclosporine) 6

SAPROPHYTE Degrade complex organic materials into simple ones, which become available for other organisms 7

13 Importance of Fungi (cont.)
MYCORRHIZAE Fungi associated with plants Symbiosis Fungi help plant roots absorb minerals and water in the soil-serve as root extensions Fungi benefit by absorbing nutrients exuded by plant roots



16 They are often called “ancient plants”
4 broad classes exist Algal fungi Sac fungi Imperfect fungi Club (basidium) fungi

17 Algal fungi All are microscopic and grow in water and damp soil
Many species in this group are responsible for blights (like Irish Potato Famine) Some species, such as Rhizopus however, are used as a source of cortisone and other "drugs"

18 Sac fungi yeasts and the blue and green molds often seen on decaying citrus fruits, in jellies and on leather Some species, like Penicillium are economically useful, but others such as Ergot (Clavicep s purpurea) which infects rye crops, can cause mass destruction In controlled doses, however, Ergot becomes an important alkaloid used to control hemmorrage (during the birthing process) as well as in the treatment of migraine Candida albicans is another species of sac fungi that is parasitic in human beings and aids in the normal functioning of the digestive tract

19 Imperfect fungi molds that mildew walls and spot clothes, as well as those that cause plant diseases, athlete's foot, and ringworm. Some of these fungi are useful like Aspergillus, used in the production of miso (fermented soy paste)

20 Club (basidium) fungi largest group of fungi which includes rusts and smuts that attack specific plants, such as corn, beans, apples, wheat, asparagus, coffee, roses and barberry many of the mushrooms in this division are edible and delicious, a large number of them, such as the Amanita's are deadly poisonous

21 8

22 FUNGAL STRUCTURE Thallus-”body” Septate-Cross Wall (Most Fungi)
Molds & fleshy fungi have these structures Long filaments of cells (hyphae) Septate-Cross Wall (Most Fungi) Coenocytic-No cross wall, continuous mass with many nuclei 10

23 12

24 13

25 Forms when environmental conditions are right
MYCELIUM Intertwined filamentous mass formed by hyphae, visible to the unaided eye Forms when environmental conditions are right 14

26 John Cooke, Oxford Scientific Films
Black Bread Mold This black bread mold growing on a piece of stale bread shows the mycelium, or interwoven filaments that make up the vegetative portion of the fungus. The small dark spots are the fruiting bodies, or sporangia, from which the spores are released. John Cooke, Oxford Scientific Films 16

27 YEAST Facultative Anaerobes Fermentation=ethanol and CO2
Non-filamentous unicellular fungi Spherical or oval Reproduction Two types exist a)Fission or b) budding 17

28 Yeast Reproduction FISSION
“even” reproduction, nucleus divides forming two identical cells, like bacteria BUDDING “uneven” reproduction, parent cell’s nucleus divides and migrates to form a bud and then breaks away

29 Safra Nimrod/Phototake NYC MichaelA. McClure PHD/Phototake NYC
Bread Yeast Bread yeast, or baker’s yeast, actually a type of sac fungi, reproduces by a process called budding. Bread yeast causes bread to rise by releasing carbon dioxide, which gets trapped in the dough. The Egyptians were the first to discover that allowing dough to ferment produced gases that made bread lighter. Safra Nimrod/Phototake NYC MichaelA. McClure PHD/Phototake NYC 18

30 DIMORPHIC FUNGI Growth as a mold or as a yeast
Most pathogenic fungi are dimorphic fungi At 37o C yeast-like At 25o C mold-like Can also occur with changes in CO2 Fungi grow differently in tissue vs nature/culture; often dictated by temp 19

31 Within Agar=mold, Agar Surface=yeast
Changes in CO2 Within Agar=mold, Agar Surface=yeast 21

32 Types of REPRODUCTION Asexually-fragmentation of hyphae
Asexually and Sexually-spores Spores: Used for Identification Four groups of true fungi Zygomycetes (common bread mold—Rhizopus) Basidiomycetes (puffballs & common mushrooms) Ascomycetes (Dutch elm disease/rye smut) Deuteromycetes (fungi imperfecti) 22

33 Classification of these groups
First three groups is based on their method of sexual reproduction 4th group, the Deuteromycetes, have NO sexual reproduction

34 REPRODUCTION (cont.) Asexual Reproduction
Progeny will be identical to parent Spores (Conidiospores, Blastospores,Chlamydospores, Sporangiospores) Hyphae fragmentation (Arthrospores) 23

Examination of asexual spores **Fungal spores are different than the endospores of bacteria Endospores are not for reproduction, but an environmentally resistant life stage Fungal spores are for reproduction, do not ensure resistance to environmental conditions 24

36 Asexual spores Conidiospores Chlamydospores Sporangiospores Blastospores

37 ASEXUAL SPORES Conidiospore
Multiple (chains) or single spores formed at the end of an aerial hypha Not enclosed within a sac Aspergillus spp. Penicillium spp. 32

38 Conidial fungus reproduces by means of asexual spores called conidia Conidia vary greatly in shape, size and color Most of the common household molds & mildews are conidial fungi

39 ASEXUAL SPORES (cont.) Another type of Conidiophore: Blastospores
A bud coming off the parent cell Candida albicans Blastospore 34

40 Blastospores 35

41 ASEXUAL SPORES (cont.) Chlamydospore Formed within hypha
Thick-walled spore Candida albicans 27

42 Chlamydospores The chlamydospore is a method of producing a substantial resting spore very quickly Nutrient is shunted from adjacent cells into a preferred cell and it swells up, converts nutrient materials to oil droplets for efficient storage, then rounds off with a thick, often roughened outer wall for protection

43 Chlamydospores

44 ASEXUAL SPORES Sporangiospores
Hundreds formed within a sac (sporangium) at the end of an aerial hypha Rhizopus spp. 29

45 30

46 Rhizopus spp 31

47 Arthrospores 1A 2 Chlamydospores 1 Conidiospores 3 1B Blastospores Sporangiospores

Acidic pH (5.0) Most molds are aerobic Yeasts are facultative anaerobes 37

High osmotic pressure Low moisture Less N2 than bacteria Complex carbohydrates Lignin(component of wood) *Saprophytes 38

50 20


52 (Some characters used in identification of deuteromycetes)


54 ALL FUNGI: are eukaryotes develop from spores
display neither flagella, cilia, nor chloroplasts have cell walls (though not necessarily ones composed of cellulose as are plant cell walls, but instead of chitin and other polysaccharides) Though displaying great variety and complexity, the fungi are routinely divided into two major groups: the macroscopic (fleshy) fungi the microscopic fungi (molds and yeasts)

55 Fungal growth requirements
In contrast to bacteria, fungi tend grow in places that are: more acidic have higher osmotic pressures are lower in moisture are low in nitrogen contain complex carbohydrates

56 Fungal structures Hyphae are one dimensional arrangements of cells.
septa are the cross walls which separate individual cells in hyphae. Mycelium are a tangled mass of hyphae. Mycelium can extensively permeate the substrate within which the fungi grows whether it be soil, water, or even living tissue.

57 Molds vs Yeast Molds Molds are aerobic, filamentous fungi including
mildews rusts smuts Molds tend to grow on surfaces rather than throughout substrates. Yeasts unicellular/nonfilamentous: Yeasts are fungi which are: typically spherical or oval facultatively anaerobic They are often observed as powdery coatings on plant material.

58 Dimorphic fungi Dimorphic fungi are fungi that behave like molds (multicellular---consist of hyphae) under some conditions, and like yeasts (unicellular---lack hyphae) under others.

59 Review

60 Fungal reproduction fungi replicate by mitosis rather than the binary fission employed by bacteria. Types of fungal reproduction, : budding fission hyphae fragmentation sporulation

61 Sexual and asexual: Fungal spores come in two varieties:
asexual spores and sexual spores Spores are used extensively to identify fungi. Asexual spores asexual spores are formed by a single parental fungi and therefore genetically identical to the parental fungi. Asexual spores come in a variety of types formed by a variety of mechanisms including: Arthrospores (sliced bread pieces) Blastospores (buds on a twig) Chlamydospores (giant cell with oil) Conidiospores (fingers) Sporangiospores (sac)


63 Ascomycetes Asexual phase- Conidiospores (Penicillium and Aspergillus & budding yeast Sexual phase (morels lichens)

64 Zygomycetes Asexual phase—Sporangium—bread mold (Rhizopus stolonifer)
Sexual phase--- sporgangium ---shotgun fungus (lives on dung) it shoots its sporgangium explosively towards light or fly pathogen (Entomophthora muscae—--these types of fungi have been used as agents for biological control of insects)

65 Basidiomycetes Basidiospore Examples: boletes, puffballs,smuts, stinkhorns and tooth fungi


Aspergillus Microsporum (dematophytes) Blastomyces Penicillium Candida Trichophyton Histoplasma Pneumocystis ? 43


69 Zygomycetes “saprophytic” molds common bread mold (Rhizopus)
coenocytic hyphae Asexual spores: Sporangiospores Approximately 600 species including bread molds (such as Rhizopus) exist


71 Ascomycetes “sac” fungi Septate hyphae and yeasts Asexual spore:
Conidiospores Approximately 30,000 species including yeasts (Saccharomyces cerevisiae), some of the molds (Aspergillus), morels, and truffles. Ascomycetes have typical reproductive structures called asci.


73 Basidiomycetes “club”fungi Mushrooms
Approximately 25,000 species including many macroscopic fungi (mushrooms, puffballs, shelf fungi) as well as a number of plant pathogens (rusts, smuts).

74 Mycosis: Fungal infection Usually chronic
FUNGAL DISEASES Mycosis: Fungal infection Usually chronic Four groups of mycoses based on degree of tissue involvement and mode of entry 44

75 Because fungi are slow growing, mycoses are generally
long-lasting TYPES OF MYCOSES Systemic Subcutaneous Cutaneous Opportunistic 45

76 SYSTEMIC MYCOSES Deep within the body
effects a number of different tissues and organs Usually soil fungi Spore inhalation=Route of transmission-starts in the lungs and spreads to other body tissues Not contagious 46

Histoplasmosis Coccidiomycosis Coccidioides immitis got renamed for the AZ Valley fever Coccidioides posadasii 47

78 Infections beneath the skin Soil and plant fungi
SUBCUTANEOUS MYCOSES Infections beneath the skin Soil and plant fungi Hyphae or spores in wounds 48

79 CUTANEOUS MYCOSES Called “Dermatophytes” Epidermis Hair Nails
Secrete keratinase-degrades keratin (protein found in hair, skin and nails) Contagious-direct contact with infected hairs and epidermal cells 30 49

80 Skin high osmotic pressure Low moisture
CUTANEOUS MYCOSES Skin high osmotic pressure Low moisture 52

Broad-spectrum antibiotics Transplant patients AIDS patients Cancer patients Ex: Stachybotrys (mold), Mucormycosis and Aspergillosis 51

82 DERMATOPHYTES Grow on keratin Hair Nails Tinea or ringworm 53

83 Capitis (scalp)-can lead to bald patches Cruris (groin)
TINEA Capitis (scalp)-can lead to bald patches Cruris (groin) Pedis (athlete’s foot) 54

Three genera involved in cutaneous mycoses: Trichophyton Microsporum Epidermophyton 55

85 TRICHOPHYTON Hair Skin Nails (Tinea ungulum) 56

86 MICROSPORUM Hair Skin 57


88 Fungi in Cutaneous Mycoses
Trichophyton Microsporum Epidermophyton Hair Skin - Nails

89 Tinea capitis Tinea capitis Tinea barbae

90 Tinea cruris

91 Tinea unguium Tinea pedis

92 More serious than cutaneous mycoses Sporothrix schenkii Soil organism
SUBCUTANEOUS MYCOSES More serious than cutaneous mycoses Sporothrix schenkii Soil organism Gardeners=ulcers on hands 60

93 Subcutaneous mycosis (mycetoma)

94 Mycetoma Mycetoma is a chronic infection of the skin, subcutaneous tissue and sometimes bone It is generally found on the foot where it is given the name watering can foot Mycetoma may be due to several fungi or actinomycetes (actinomycetoma). Actinomycetes are bacteria producing filaments like fungi. Both the fungi and the actinomycetes are found in soil and plant material in tropical regions. The organism is inoculated into the skin by a minor injury, for example, a cut with a thorn when barefoot.

95 Mycetoma—a deep fungal infection

96 Clinical features Mycetoma is more common in men than women, particularly those aged 20 to 50. It generally presents as a single lesion on an exposed site and may persist for years. It starts as a small hard painless lump under the skin. It grows slowly but eventually involves underlying muscles and bones. The middle of the lesion caves in, ulcerates and discharges pus, which contains grains. Eventually, sinus tracts (holes) develop which also discharge pus and grains. The surface skin is scarred and pale. Considerable deformity often makes it difficult to walk. Mycetoma may cause no discomfort but it often itches or burns. Secondary bacterial infection is common. Treatment is slow

97 Mucosal normal microbiota suppresses the growth of Candida albicans
CANDIDIASIS Mucosal normal microbiota suppresses the growth of Candida albicans 62

98 CANDIDIASIS (cont.) Vaginitis and thrush are initiated by:
Antibiotics eliminate normal microbiota pH changes Infants that may not have their normal microbiota established=thrush 63

99 Candidiasis Thrush Vaginal

100 Hematogenous dissemination Kidney Spleen Lung Liver
CANDIDIASIS (cont.) Hematogenous dissemination Kidney Spleen Lung Liver 64

101 Invasive candidiasis

Histoplasmosis-resembles TB, starts in the lungs, most cases are minor Histoplasma capsulatum Coccidioidomycosis Coccidioides immitis in CA Coccidioides posadasii in AZ 66

Blastomycosis Blastomyces dermatidis Pneumocystis pneumonia Pneumocystis carinii 67

104 Resembles tuberculosis May affect all organs Vague symptoms
HISTOPLASMOSIS Resembles tuberculosis May affect all organs Vague symptoms Yeast lives within macrophages and multiplies 68

Histoplasma capsulatum Dimorphic fungi Mississippi river and Ohio river states 69

Very low mortality 50/year/USA Transmission Airborne conidia Bats: Carry fungus in feces Birds: Feces 70

Diagnostic Blood test—AB titer Treatment Amphotericin B Itraconazole 71

108 Histoplasmosis second most significant fungus disease
It is infectious but not contagious The "summer flu" that Midwesterners use to get often is now thought to have been histosplasmosis Histoplasmosis basically is a pulmonary or respiratory disease, but may extend to the liver, lymph nodes, and spleen; it may disseminate to the blood and bone marrow and be fatal The victim frequently has chills and fever to 105 degrees, night sweats, chest pains, and fatigued. A non-productive cough is fairly common.

109 Histoplasmosis 72

110 Coccidioides posadasii Dimorphic fungi
COCCIDIOIDOMYCOSIS Valley fever Coccidioides immitis Coccidioides posadasii Dimorphic fungi 73

Southwest deserts Arthrospores in dry alkaline soils San Joaquin Valley (CA) Tucson area 74

112 RANGE OF CASES OF VALLEY FEVER: inapparent -- 60% mild - moderate --30% complications % fatal--<1%

Symptoms Chest pain Fever Cough Extreme fatigue 77

114 Immunosuppressed Patients-- organ transplant lymphoma HIV+/AIDS
RISK FACTORS FOR DISSEMINATED DISEASE: Immunosuppressed Patients-- organ transplant lymphoma HIV+/AIDS adrenal corticosteroid therapy diabetes 3rd trimester pregnancy Gender male Race African-American Filipino

115 75

116 Valley Fever

117 COCCIDIOIDOMYCOSIS In tissues C. immitis forms spherules
Thick-walled structures filled with spores In soil, forms filaments that reproduce by the formation of arthrospores, transmitted by wind, 100,000 infections per year 76

118 Life cycle of C. immitis Spherule form (top half) multiplies in
the lungs; mycelia (bottom half) grow in the soil

119 C. immitis spherule in lung tissue

120 Brain lesions caused by C. immitis Spherules in brain tissue

Most infections are asymptomatic Most recover in a few weeks 78

Solid immunity follows recovery 1/1000 cases a tuberculosis-like condition develops throughout the body 79

Diagnostic Resemblence to TB requires Identification of spherules in tissues deaths in the USA 92% San Joaquin Valley 81

124 Blastomyces dermatitidis or North American Blastomycosis
Dimorphic fungus Soil in Mississippi Valley 83

125 Most infections are asymptomatic Begins at lungs and spreads
BLASTOMYCOSIS (cont.) Most infections are asymptomatic Begins at lungs and spreads 30-60 deaths/year 84

126 BLASTOMYCOSIS (cont.) Cutaneous ulcers Abscess formation
Tissue destruction 85

127 Blastomycosis—Glichrists Disease
Blastomycosis is a chronic, systemic fungal disease that affects humans The disease affects the lungs. It is caused by Blastomyces dermatitidis. The main route of infection is by inhalation of spores The disease is infectious but is not contagious. Major symptoms in humans include loss of weight, fever, cough, and bloody sputum and chest pains. The disease may disseminate into the skin, bones, or urogenital tract.

128 Isolation of organism from pus and biopsies Treatment Amphotericin B
BLASTOMYCOSIS (cont.) Diagnostic Isolation of organism from pus and biopsies Treatment Amphotericin B 86

Pneumocystis carinii Opportunistic pathogen Leading cause of death in AIDS patients Present in healthy lungs Immunosuppressed individuals 89

Rare before AIDS epidemic Less than 100 cases/year 1993-Indicator of AIDS Currently, one of the most common infectious diseases 90

Aspergillus fumigatus Aspergillus spp.-present in decaying vegetation Rhizopus spp. Mucor spp. 87

132 Those darn pigeons!! Cryptococcosis: Yeast Meningitis Affects: Humans The disease is caused by a systemic pathogenic yeast called Cryptococcus Neoformans, which is found worldwide. Cryptococcosis in humans usually begins as a primary infection of the lungs. There are no visible early symptoms may include cough, chest pain, weight loss, fever or dizziness. The disease may be in the lungs, mucous membranes, bones, and joints, with no organ or tissue of the body exempt. It very frequently involves the brain covering as cryptococcal meningitis. Pigeon excreta is the most common source of C. Neoformans. The yeast is carried in the intestinal tract of pigeons. Pulmonary cryptococcsis has occurred in the workmen who have been exposed to the yeast while demolishing old buildings where pigeons had roosted. Most of the cryptococcal infections occur from inhalation of the fungas along with the dust from areas enriched with pigeons manure.

133 Other diseases associated with pigeons
Salmonellosis is more than just food poisoning. Pigeons are important factors in the spread of salmonellosis, since the bacteria are left wherever the pigeons defecate Pigeons trample back and forth through their copious excretions on ledges and air intake vents The dust enters through air conditioners and ventilators. S. Typhimurium var. Copenhagen is the most common salmonella isolated from pigeons Salmonellosis in humans may manifest itself in one or more of four types (1) temporary carriage without infection (2) Gastroenteritis (food poisoning) (3) enteric fever septicemia (blood poisoning) (4) Persistent infection

134 98

Compost piles Farmers and gardeners Impaired immunity Treatment Amphotericin B 88

136 Antifungal antimicrobials
Amphotericin B, nystatin (Streptomyces nodosus) miconazole Monistat 3 (azole) Relatively toxic-Kidneys Amphotericin should be used primarily for treatment of patients with progressive and potentially life-threatening fungal infections; it should not be used to treat noninvasive forms of fungal disease such as oral thrush, vaginal candidiasis and esophageal candidiasis, in patients with normal neutrophil counts. Miconazole nitrate inhibits the biosynthesis of ergosterol, an essential component of the fungal cell wall. Miconazole nitrate has also been shown to interact with the synthesis of triglycerides and fatty acids, and to inhibit fungal oxidative and peroxidase enzymes.

Mycotoxins: Fungal Toxins Ergot poisoning Aflatoxin poisoning 93

138 Ergotism: Disease caused by ingestion of contaminated grains
ERGOT POISONING Claviceps purpurea Infects Grain Crops Ergotism: Disease caused by ingestion of contaminated grains Claviceps-contaminated grains (rye or wheat) 94

139 Claviceps purpurea as recently as 1951, in Pont-St. Esprit, a small town in France, there was an outbreak of the disease. In Europe it is the custom to buy fresh bread nearly every day.

140 In this small town there was only one bakery and everyone bought bread from it. Strange things started happening. People developed a burning sensation in their limbs, began to hallucinate that they could fly, did strange things to their dogs with forks and in general acted weirdly. This outbreak is chronicled in a marvelous (but out of print) book called "The day of St Anthony's Fire" by John Grant Fuller. St. Anthony is the patron saint of lost causes When all of the other saints have failed, St. Anthony is the one you are supposed to pray to. And St. Anthony's fire was rampant in the town that day. Similar outbreaks probably occurred throughout the world wherever the conditions were right for the growth of Claviceps purpurea.

141 The chemical responsible for the hallucinations is actually LSD
The chemical responsible for the hallucinations is actually LSD! lysergic acid. There was even an outbreak of ergotism on the television show "Quincy" starring Jack Klugman, who played a coroner. He was aboard a cruise ship and people were acting very strangely. Quincy finally traced the behavior to contamination of the flour tortillas that had been served aboard ship.

142 The X-Files also had an episode featuring ergot, although it had a surreal twist (of course). In that episode, Scully got a tattoo that caused her to hallucinate (she thought the tattoo was talking to her). Turns out the tattoo artist was an ex-con who learned his art in prison. He collected plants in the prison yard and extracted dyes from them for his tattoos.

143 Another ergot derivative may cause spontaneous abortions in animals-- in small doses this same drug is used to aid in childbirth. Another of the ergot derivatives is used to cure migraine headaches.

Gangrene Psychotic delusions Convulsions Abortion 95

Witchcraft in Salem (1690s) Similar Behavior caused by Lysergic acid (LSD) 96

146 There have been various attempts to explain those witch trials
There have been various attempts to explain those witch trials. None of them are more logical and interesting than the hypothesis of ergot poisoning, caused by Claviceps purpurea. The behavior was not identified as witchcraft until 1691, and this was just the beginning of the problem. All of the accused had similar symptoms: manic melancholia, psychosis, delirium, crawling sensations of the skin, vertigo, headaches, vomiting and diarrhea. All of these are symptoms of ergot poisoning, and it is likely that at least the initial hysteria was started by Claviceps purpurea infecting the grains of rye compelling, although circumstantial, evidence that the Salem witch trials coincided with a weather period that would have produced large quantities of ergot on rye, which was grown in the lowlands in that area.

147 "The Trial of George Jacobs, August 5, 1692. " By T. H. Matteson, 1855
"The Trial of George Jacobs, August 5, 1692." By T. H. Matteson, Oil painting. Peabody and Essex Museum, with permission.

148 Aflatoxin Aflatoxin is a naturally occurring mycotoxin produced by two types of mold Aspergillus flavus and Aspergillus parasiticus. Aspergillus flavus is common & widespread in nature and is most often found when certain grains are grown under stressful conditions such as drought. The mold occurs in soil, decaying vegetation and hay At least 13 different types of aflatoxin are produced in nature with aflatoxin B1 considered as the most toxic While the presence of Aspergillus flavus does not always indicate harmful levels of aflatoxin it does mean that the potential for aflatoxin production is present.

149 Aflatoxin poisening Aspergillus flavus Peanuts and cottonseeds
Acute intoxication Liver damage 97

Chronic intoxication Liver cancer Depending on the levels, the toxins can severely affect the liver and they are a known human carcinogen 99

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