2. Mycotoxins and Mycotoxicoses
• Mycotoxins are fungal secondary metabolites that are toxic
when consumed by animals and man.
• The disease resulted by consuming mycotoxins are called
mycotoxicoses.
• One mold species may produce many different mycotoxins,
and the same mycotoxin may be produced by several species
• Mycotoxins accumulate in maturing corn, cereals, soya beans,
sorghum, peanuts and other food and feed crops in the field
and in grain during transportation and storage.
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3. • Mycotoxins can appear in the food chain as a result of fungal
infection of crops, either by being eaten directly by humans or
by being used as livestock feed.
• Mycotoxins greatly resist decomposition or being broken
down in digestion
– they remain in the food chain in meat and dairy products
– Even temperature treatments, such as cooking and freezing,
do not destroy some mycotoxins.
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4. Types of Mycotoxins
1. Aflatoxins
• Produced by Aspergillus flavus and A. parasiticus
• The fungi are common in soils and involved in decay of plant
materials
• Invade grain under storage and in the field
• More serious in tropical and subtropical countries where
cereals, peanuts and corn are important source of diet
• Attack all species of animals
• Cause liver cancer in human
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5. 2. Ergot alkaloids
• Produced by Claviceps purpureae
• The alkaloids produced by the black sclerotium (ergot)
• The chronic ergot poisoning cause gangrene, cramps, vomiting
and fatal in sever cases
• The ergot fungus infects the flowers of cereals and many
grasses when flowering occurs during cool & moist weather
• It produces a characteristic black, spur like sclerotia that
replace the seed
• Sclerotia is the ergot body
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6. • Ergot alkaloids is important from medical point of view:
– used for menstrual disorders
– intestinal bleeding
– decrease blood pressure
– contract smooth muscles (uterus)
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7. 3. Zearalenone
• Produced by Fusarium species
• Cause estrogenic syndrome which is characterized by swollen
edematous vulva with enlarged mammary glands
• In young males, cause shrinkage of the testis
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8. 4. Ochratoxin
• Produced by Aspergillus ochraceus and penicillium
viridicatum primarily
• Produced in food and feed grains
• Chiefly attacks poultry and swine
• Damages kidneys and liver
• Carcinogenic
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9. 5. T 2 Toxin
• Is a tricothecene produced by Fusarium
• Is one of the deadly known toxin
• Damage all digestive tract and cause rapid death due to
internal hemorrhage
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10. 6. Vomitoxin
• Produced by Fusarium
• Cause acute GIT illness
7. Sterigmatocystin
• Produced by A. versicolor
• Carcinogenic
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12. • Fungal infections are called mycoses
• People are at risk of fungal infections:
– taking strong antibiotics for a long period of time
• because antibiotics kill not only damaging bacteria, but
healthy bacteria as well
• this alters the balance of microorganisms in the mouth,
vagina, intestines and other places in the body
• results in an overgrowth of fungus.
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13. • Individual with weakened immune systems are also at risk of
developing fungal infections.
– people with HIV/AIDS
– people taking immunosuppressive therapy (chemotherapy)
– People with diabetes
• Very young and very old people, also, are groups at risk.
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14. Types of mycoses
A. Superficial mycoses
• Disease limited to the outer most layers of the skin and hair
e.g. Malassegia furfur
• Dermatomycoses
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15. B. Cutaneous mycoses
• extend deeper into the epidermis, and also include invasive
hair and nail diseases
• The organisms that cause these diseases are called
dermatophytes (Microsporum, Trichophyton, and
Epidermophyton fungi), which together comprise 41 species
• The resulting diseases are often called ringworm (even though
there is no worm involved) or tinea.
• One common disease is the athlete's foot which most
commonly affects men and children before puberty.
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16. 3. Subcutaneous mycoses
• Deeper layer of skin, sometimes even bone
• These infections are chronic and can be initiated by piercing
trauma to the skin which allows the fungi to enter.
• These infections are difficult to treat and may require surgical
interventions
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17. 4. Systemic mycoses
• Also called deep mycoses
• Affect internal organs disseminate to multiple sites of the body
• Caused by dimorphic fungi such as Cryptococcus Neoformans
• pathogens originate primarily in the lungs and may spread to
many organ systems
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19. 5. Opportunistic mycoses
• Opportunistic fungi do not cause disease under normal
condition.
• They cause disease under special conditions such as:
– in immunologically compromised individuals such as
• AIDS patients
• extensive antibiotic users
• mmunosuppressive drugs
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20. Examples of opportunistic mycoses
A. Candidiasis
• Are acute to chronic fungal infections
• Involve mouth, vagina, skin, nails, bronchi (lung), alimentary
tract, blood stream, UTI.
• Risk factors include:
– Age
– Pregnancy
– Diabetes
– AIDS
– long term antibiotic use.
– Burns
– Drug abuse
– Gastrointestinal damage
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21. • Candida albicans
– is part of normal flora of skin, vagina, mucous membrane,
and GIT.
– Cause:
• oral trash:cause white curd like patches in the mouth
• Vulvovaginitis: thick yellow white discharge, burning
serration
• Cutaneous candidiasis: involves nails
• GIT, blood infection, bronchopulmonary infection etc.
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22. B. Cryptocococcuses
• Most often cause meningitis and pulmonary infections
e.g. C. neoformans
C. Aspergilloses
• Caused by A. fumigatus and A. flavus
• Cause:
– allergic bronchopulmonary diseases
– Aspergillus pneumonitis
– Keratitis
– otomycosis (ear external infection)
– Aspergillus asthma etc.
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23. D. Pneumocystis carni pneumonia
• Caused by P. carinii
• Is the major cause of morbidity and mortality in immune
compromised people
E. Zygomycosis(Mucor mycosis, phycomycosis)
• Caused by Rhizopus and mucor
• Growth of cotton like growths (fungal colonies) on the roof of
mouth or naves in diabetic patients
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24. F. Fusarium
• Some times cause diseases in HIV/AIDS patients.
• It infects nails
G. Penicillum
• Sometimes cause keratitis, penicilliosis, otomycosis
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25. Treatment
• Antifungal drugs are used to treat mycoses.
• Depending on the nature of the infection, a topical or systemic
agent may be used.
• Photochemotherapy is a technique used at medical centers for
the treatment of mycosis
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26. Prevention
• Keeping the skin clean and dry, as well as maintaining good
hygiene, will help larger topical mycoses.
• Because fungal infections are contagious, it is important to
wash after touching other people or animals.
• Sports clothing should also be washed after use.
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27. Plant Diseases
• Plant diseases reduce the harvest of food worldwide by about
30% each year.
• 70% of plant (crop) diseases are caused by fungi
• Diseases can take many forms, and cause many different types
of symptoms in host plants.
• Ex: necrosis (death), wilts, loss of fruit, economic damage to
harvested crops
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28. Fungi as plant parasites
• Necrotrophic parasites:
– are parasites which kill off the host cells & feed
• Biotrophic parasites:
– absorb nutrients from host cells without killing the cell
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29. Seedling pathogens of fungi
• Pythium spp: attack the emerging root tip
• Rhizoclonia solani: attack the young shoot base
• Fusarium spp: seed rot of cereals
Fruit diseases
• Fleshy fruits are rotten by some fungi
• Botrytis cineria: cause grey mould of soft fruits such as straw
berry, grapes
• P. italicum cause citrus fruits to rot
• P. expansum cause the rotting of apple
Wood rots
• Armillaria spp: it rots the wood and kill trees such as coffee
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31. 1.Tomato early blight (Alternaria solani)
• caused by a soil-borne fungus, can over winter in plant debris
on the ground.
• causes dark sunken lesions on mature fruit, concentric rings
of necrosis, fruit often falls from the plant before harvest.
• also causes defoliation of the host plant
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32. 2. Grey Mold (Botrytis cinerea)
• caused by a soil-borne fungus, easily invades new tissue on
many plants.
• requires high humidity, close proximity of other plants.
• attacks stems first, causes black slimy lesions, which cause the
plant to die.
• lesions on fruit cause economic loss.
Grey Mold of bean, (Botrytis cinerea)
Botrytis mold on raspberries and strawberries
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33. 3. Corn Smut (Ustilago zeae)
• overwinters in soil as spores, which can survive in soil for over
3 years.
• causes ears of corn to turn black, with a greasy appearance.
Large amounts of
• spores are produced within the infected ears.
• these spores can be blown on the wind to other plants.
Corn smut, Ustilago zeae 33
34. 4. Potato Late Blight (Phytophthora infestans)
• one of the most devastating plant diseases, it is responsible for
the Irish Potato Famine of the 1800’s.
• caused by a fungus, it will defoliate an entire field of potatoes
in a few days.
• tubers are also infected, and cause the disease to be transmitted
over years.
Infected tuber
Defoliated Plant
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35. 5. Black Spot on Rose (Diplocarpon rosae)
• a fungal disease, it causes black spots to form on leaves. The
spots eventually cover the entire leaf, which then falls off. All
of the leaves will fall eventually.
• defoliation of the plant leaves it open to drought and insect
damage.
• damaged plants may not live next year.
Black Spot on Rose (Diplocarpon rosae)
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36. 6. Fire Blight of Apple and Peach (Erwinia amylovora)
• a bacterial disease, spread by rain, as well as by insect vector.
• infects through the flowers, in early spring.
• causes a distinctive “shepherds crook” on infected limbs.
Limbs appear burned and the entire tree will eventually die.
Peach Limbs With Fire blight Apple Limbs With Fire blight
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37. Control of Plant Diseases
• There are a variety of methods for the control of plant disease.
A. Cultural control: the use of specific techniques or practices to
eliminate or mitigate the pathogen.
– disinfecting pruning equipment
– removal of dead plants and plant debris
– spacing of crops to allow drying
– crop rotation
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38. B. Biological Control: using plants that are immune to the
pathogen, or are at least tolerant.
– Using biopesticides (beneficial bacteria)
• which outcompete some diseases (mostly Erwinia)
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39. C. Chemical control: the use of some pesticide to kill either the
pathogen or its vector. This usually has to be done over the
course of a season, not just once.
– Spraying fields to kill off the late blight fungus
– spraying antibacterial chemicals on fire blighted trees
– injecting trees with insecticide and fungicide to kill the
fungus and the vector
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41. Fungal Biotechnology
• Biotechnology which can simply be defined as:
– application of living organisms and their components to
industrial products and processes
• Biotechnology also offers the potential for new industrial
processes that require less energy and are based on renewable
raw materials.
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42. • Biotechnology encompasses two distinct phases: Fermentation
and Product recovery
• Fermentation procedures must be developed for the cultivation
of microorganisms under optimal conditions and for the
production of desired metabolites or enzymes by the
organisms.
• Product recovery involves the extraction and purification of
biological products
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43. • Some of the most important organisms used in biotechnology
are fungi.
• Only a few examples of the products and processes involving :
– Food Applications
– important industrial products (chemicals, pharmaceuticals)
– Processes (degrade toxic wastes)
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44. Food Applications
Brewing and baking
– conversion of sugar into alcohol and carbon dioxide by yeasts
• In bread making carbon dioxide causes the dough to rise
giving lightness to the bread whilst the alcohol is driven off
during baking.
• Early processes were dependent on contamination by 'wild'
yeasts.
• Today pure strains are normally employed of baker's yeast
(Saccharomyces cerevisiae) are produced worldwide every
year.
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45. Cheese production
– Penicillium roqueforti
– Penicillium candidum
– Penicillium caseicolum
– Penicillium camemberti
• play an important role in the development of the characteristic
flavors of these cheeses.
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46. Edible mushrooms
• Cultivation of edible mushrooms outdoors has been practiced
for thousands of years
• More consistent crops and much higher yields were obtained:
– following the development of pure spawns
– sterilization/pasteurization technology
– a better understanding of substrate requirements and
– the use of environmentally controlled mushroom houses
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47. Quorn myco-protein /SCP
• A recent innovation in food technology has been the
– development of Quorn myco-protein
– from a filamentous fungus of Fusarium venenatum.
• The filamentous nature of the biomass is responsible for the
meat-like texture and appearance of the final product.
• single-cell protein, or SCP, describes the protein-rich cell mass
derived from microorganisms grown on a large scale for either
animal or human consumption.
• SCP has a high content of protein containing all the essential
amino acids
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48. • Microorganisms are an excellent source of SCP because of:
– their rapid growth rate
– their ability to use very inexpensive raw materials as
carbon sources
– the uniquely high efficiency, expressed as grams of protein
produced per kilo gram of raw material
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50. Useful Products
• important industrial products (chemicals, pharmaceuticals etc.)
– produced from fungi using fermentation technology
• Early fermentations used open processes under nonsterile
conditions but this changed in the 1940s
– with the introduction of the stirred-tank bioreactor for penicillin
manufacture
• which required the development of novel engineering techniques to exclude
contaminating microorganisms.
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51. • An example of a major commodity chemical manufactured by
fungal fermentation is
– citric acid which is widely used in the food and pharmaceutical
industries.
– antibiotics
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52. Other Processes
• Fungi can be used in new production processes that are
themselves less polluting than traditional chemical processes
• some species of white rot fungi are already being employed to
degrade toxic wastes/ Bioremedation
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53. • Bioremediation depends on the activities of living organisms
to clean up pollutants dispersed in the environment.
• Physical or chemical treatments, such as vaporization,
extraction, or adsorption, relocate rather than remove
pollutants.
• In contrast, there are many instances in which biodegradation
converts organic pollutants to harmless inorganic products,
including carbon dioxide, water, and halide ions.
• Other advantages are that bioremediation is generally
inexpensive and causes little disturbance to the environment.
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54. • Lignin-degrading (note: decay caused by these
species gives wood a bleached appearance)
– such as Phanerochaete chrysosporium and
Trametes versicolor
• replace some of the chemical steps used in
paper making.
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55. • The use of fungi as biocontrol agents to kill:
– insects (mycoinsecticides)
– weeds (mycoherbicides)
• has the potential to replace many of the toxic chemicals
currently in use.
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57. ANTIBIOTICS PRODUCED BY FUNGI
A. Penicillin
• First produced from P. notatum, currently produced from p.
chrysogenum in cultures for high yield
B. Cephalosporins
• Produced from moulds called Cephalosporium
• Cephalosporins breakdown bacterial cell wall
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58. C. Cycloserine
• Inhibits bacterial cell wall synthesis
• Produced by Trichoderma polysporum
• It is immune suppressant
• Not used as fungicide
D. Gliotoxins
• Have immunological and antibiotic activity
• Produced by fungi such as A. fumigatus
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59. E. Griseofulvin
• Produced by P. griseofulvin
• Is fungistatic
• Used for the treatment of dermatophytes applied topically
• Production industrially is simple and cheap
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60. F. Statins
• Produced by A. griseus a soil born fungi
• It removes lipoproreins from blood vessels in humans
• It acts in the liver on an enzyme which makes cholesterol and
hence stop cholesterol formation
• It reduces the chance of heart attack and diabetes
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62. Isolation of fungal antibiotics
• Three steps involved:
1. Culture
• the fungus expected to produce antibiotic has to be cultured in
the laboratory
2. Bioassay
• is a biological method of detection of a substance
– detects the effect of a given fungal product on living organism
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63. 3. Extraction
• isolation of the active substance (the antibiotic) from the fungi
• It involves:
– Screening
– identification of microbial products
• The process of isolation and purification of antibiotics is called
downstream process (product recovery)
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64. DESIRED PRODUCT IN CULTURE BROTH
INTRACELLULAR
PRODUCT
EXTRACELLULAR
PRODUCT
CELL DISRUPTION (physical,
chemical, enzymatic methods)
BROTH WITH SOLID AND LIQUID
SOLID-LIQUID SEPARATION
(Flocculation, Flotation,
Filtration, Centrifugation)
CONCENTRATION
(Evaporation, membrane
filtration, precipitation,
adsorption)
FORMULATION
(Drying, freeze drying,
crystallization)
FINAL PRODUCT
Fig. A summary of the major steps in downstream processing 64
65. • Intracellular metabolites: these products are located within the
cells.
– Nucleic acids
– Vitamins
– Enzymes
– Certain antibiotics (e.g. Sisomicin and Griseofulvin)
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66. • Extracellular metabolites: they are present outside the cells (in
culture fluides)
– Amino acids
– Citric acid
– Alcohol
– Some enzyme (amylase and proteases)
– Most antibiotics
• In a few cases, metabolites are found both in the cells and the
culture filtrates; e.g. Flavomycin, Vitamin B12
66
67. • Test Two
– Fungal reproduction
– Fungal association with other organisms
– Mycotoxin
• December 28/2015
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68. • Assignment one (10%)
– Literature review report on
• Antifugal therapy
• Hallucinating mushrooms
• Evaluation of each review will be based on originality of the
review, relevance of the content and understanding of the
topics
• Group work- peer learning grouping
• January 1/2016
68
