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Aspergi l lus sp. as aflatoxinproducers in grains and feeds
STKM 6113
ADVANCED FOOD
MICROBIOLOGY
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Introduction
Secondary metabolites
produced by fungi
(molds)
Mycotoxins?
Harmful to human andanimal health
INTRODUCTION
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a filamentousand ubiquitousfungus found innature
includes over 185 species
20 reported as causative agents of
opportunistic infections in man
A. fumigatus (most commonly isolated),A.flavus, A. niger, A. clavatus, A. oryzae, etc..
Aspergillus sp.
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Produce spores(conidiospores
or conidia)
MORPHOLOGICAL
CHARACTERISTICS
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Air
water
soil
manure
Sawdustlitter
Animal
feed
On animal
Plant
debris
WHERE ISASPERGILLUSFOUND?
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Vary in color, size and growth rate
Except forA. nidulans andA. glaucus,
the growth rate is rapid to moderately
rapid
A. nidulans andA. glaucus grow
slowly and reach size 0.5 1 cm
(25C, 7 days on Czapek Dox agar)
MACROSCOPIC FEATURES
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A. f lavus
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A. fumigatus A. niger
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A. oryzae : production of soy sauce and
sake
A. niger : production of citric acid and
enzymes eg. Glucose oxidase & lysozyme
A. flavus andA. parasiticus : produce
aflatoxin
ASPERGILLUS: GOOD OR BAD?
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AFLATOXIN
Carcinogenicmycotoxinsformed by anumber of fungi in the genusAspergillus
Most toxic and dangerous mycotoxins Highly toxic to livestock, poultry and people
can be produced during harvest, storage,production, transportation and
processing of cereals (e.g., corn) peanuts,cottonseed and tree-nuts
Considered as unavoidable food
contaminants by US FDA
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the most hepatotoxic,
carcinogenic and
mutagenicof all food-borne related aflatoxins
toxicity varies among
animal species, with
poultry and dogs being
the most sensitive
classified by theInternational Agency for
Cancer Research in the
group I of molecules that
are carcinogenic for both
humans and animals
MOST COMMON
AFLATOXINS FROM
ASPERGILLUSAFB1
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Stable
Colorless
Odorless
Tasteless
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Blacklight test
Simply detects
compoundsthat fluoresce
Sample for
further testing
Minicolumn
test
Give false
positive result ifused
improperly
Serological test
No specialzed
labs
No trainings or
equipments
Give accurate
results
Indicate presenceand amount
e.g ELISA
1 2 3
HOW TO DETECT AFLATOXIN
CONTAMINATION?
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Intended use Aflatoxin level (ppb)
Milk (Dairy Feed) None detected
Corn of unknown destination
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AFLATOXICOSIS
Disease caused by the consumption of
aflatoxins.
Can be acute, sub-acute or chronic,
depending on the toxin amount consumed,
the exposure period and species-specific
susceptibility
For humans, aflatoxin is predominantly
perceived as an agent promoting liver
cancers
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SYMPTOMS
Feed
refusal
Rough haircoat
Weight loss
Reducedgrowth rate
Milddiarrhea Impair
reproductive
efficiency
Abortions
Impair
immunesystem
response
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Don't keep grains and nuts (particularly,
corn, peanuts and cottonseed) for long
periods (more than a few months) before
eating them.
Store them in a dry (low humidity) cool
environment - a freezer is excellent!
Buy from known, reputable sources -
where you know it is fresh and has been
handled properly.
HOW TO AVOID AFLATOXINS?
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OUTBREAKS
Outbreak of Aflatoxin Poisoning-
Eastern and Central Provinces,
Kenya, January-July 2004
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A total of 317 cases were reported by 20 July2004, with a case fatality rate of 39%.
This epidemic resulted from ingestion of
contaminated maize.
The 2004 outbreak resulted from widespread
aflatoxin contamination of locally grown maize,which occurred during storage of the maize
under damp conditions.
Aflatoxin poisoning likely will continue to be a
public health problem until culturally
appropriate storage methods for dry maize areimplemented by the local population.
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A total of 317 cases had been reported, with 125deaths
Of the 308 patients for whom age data were
available, 68 were aged 15 years.
Preliminary results indicated widespread, high-
level aflatoxin contamination. A total of 182(53.2%) of 342 samples had >20 ppb of aflatoxin.
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The government of Kenya is providing replacement food in the most heavily
affected district
Residents of affected districts have been advised to avoid consumption ofmaize or other foods suspected to be moldy or appearing discolored
In addition, food inspections by public health authorities are being conducted,and suspect food is being seized, destroyed, and replaced
Surveillance for possible aflatoxin poisoning in humans has been extended toother parts of Kenya by MOH, and aflatoxin screening of maize has been
increased.
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Incidence of aflatoxinin peanuts(Arachis hypogaea Linnaeus)from markets in Western, Nyanza and Nairobi Provinces of
Kenya and related market traits
Published on 24 October 2012
TITLE
The susceptibility of peanuts to infection with aflatoxinproducing fungi has been noted elsewhere and high levels of
aflatoxinhave been recorded in the nuts.
PROBLEM
STATEMENT
Characterized peanut market outlets in Nairobi, Westernand Nyanza Provinces of Kenya
Established the incidence and contamination levels of
aflatoxinin peanut products from major markets in Kenya
Studied the effect of lowering regulatory levels for aflatoxin
in peanut products in Kenya on trade and availability for
human consumption Determined the effect of peanut market practices on the
levels of aflatoxinin peanuts from Kenyan markets
OBJECTIVES
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MAIN POINTS OF DISCUSSIONS
Aflatoxin contamination could be further aggravated by poor storage facilities, which
was evident from the high proportions of peanuts recorded as infested with insects and
stored in dusty, poorly ventilated premises
Their low contamination levels could be attributed to the fact that a major proportion is
sold in shell, which acts as a protective shield against entry of aflatoxin-producing fungi
CONCLUSIONS
Sorting and use of other low cost technologies have been shown to substantially reduce
aflatoxinlevels in peanuts and hence such approaches coupled with alternative use of
contaminated nuts should be recommended together with regulatory approaches in the
education campaigns.
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REFERENCES Adjovi, Y.C.S., Bailly, S., Gnonlonfin, B.J.G., Tadrist, S., Querin, A., Oswald,
I.P., Puel, O., Bailly, J.D. & Sanni, A. 2014. Analysis of the contrastbetween natural occurrence of toxigenic Aspergilli of the Flavi sectionand aflatoxin B1 in cassava. Food Microbiology38: 151-159.
Bruchim, Y., Segev, G., Sela, U., Bdolah-Abram, T., Salomon, A. & Aroch, I.2012. Accidental fatal aflatoxicosis due to contaminated commercial dietin 50 dogs. Research in Veterinary Science93: 279287.
Cassel, E.K., Campbell, B., Draper, M. & Epperson, B. 2001. AflatoxinsHazards in Grains / Aflatoxicosis and Livestocks.
Giorni, P., Battilani, P., Pietri, A. & Magan, N. 2008. Effect of aw and CO2level on Aspergillus flavus growth and aflatoxin production in high
moisture maize post-harvest. International Journal of Food Microbiology122: 109113.
Klich, M.A. 2007. Environmental and developmental factors influencingaflatoxin production by Aspergillus flavus and Aspergillus parasiticus.Mycoscience48:7180.
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