Aspergillus sp as Aflatoxin Producers in grains and feeds

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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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Documents

Aspergillus sp as Aflatoxin Producers in grains and feeds