Importance of Aflatoxin: Summary of biocontrol projects in Burkina Faso

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Importance of Aflatoxin

Summary of Biocontrol Project in

Burkina Faso

Importance of Aflatoxin

Summary of Biocontrol Project in

Burkina Faso

Ranajit BandyopadhyayIITA, Ibadan, Nigeria

www.iita.org

• Highly toxic metabolite produced by the ubiquitous Aspergillus flavus fungus

• The fungus resides in soil and crop debris, infects crops and produces the toxin in the field and in stores

Aflatoxin Facts

• Contamination possible without visible signs of the fungus

• Fungus carried from field to store

Photo: Peter Cotty

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• Unlike most fungi, Aspergillus flavus is favoured by hot dry conditions.

• The optimum temperature for growth is 37 C, but the fungus readily grows between the temperatures of 25-42 C, and will grow at temperatures from 12-48C.

• Toxin contamination more when night temperatures are high

• Drought stress predisposes plants to aflatoxin

Disease Development & Weather

Source: www.aspergillusflavus.org

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Aflatoxin Contamination Occurs in Two Phases

Phase I: Before Crop Maturity Developing crops become infected. Associated with crop damage (insect, bird, stress). Favored by high temperature (night) and dry conditions.

Phase II: After Crop Maturity Aflatoxin increases in mature crop. Seed is vulnerable until consumed. Rain on the mature crop increases contamination. Associated with high humidity in the field & store, insect

damage, and improper crop storage or transportation.


Pre‐Harvest Problem

Aflatoxin (ppb)ppb)

Peanut (n = 188) Maize (n = 241)

Distribution (% samples)

> 4 54 70> 10 41 52> 20 29 24

Descriptive statistics (ppb)

Minimum < LOD < LODMaximum 3487 838

Mean 111 33LOD = Limit of Detection; States sampled: Nassarawa, Katsina, Kaduna, Kano, Bauchi, Jigawa & Niger

Aflatoxin in Groundnut and Maize at Harvest, 2012, Nigeria

Increases in store


Post‐Harvest Aflatoxin

Aflatoxin in Groundnut and Maize in Farmers’ Store in Burkina Faso

Crop Zone B‐aflatoxin (ppb)Mean Range

GroundnutSudan Savannah 46.0 0.0 – 925.0

Northern Guinea Savannah 11.3 0.0 – 41.0Southern Guinea Savannah 12.3 1.0 – 21.0

MaizeSudan Savannah 49.6 2.0 – 517.0

Northern Guinea Savannah 17.8 2.7 – 127.0Southern Guinea Savannah 7.0 0.0 – 11.7

Prevalence of Aflatoxins in Food & Feed

• Several African staple commodities affected• High human exposure in Africa – mother to baby• Levels and frequency of occurrence high• Concern for food and feed processors, government

and emergency food reserve agencies, school‐feeding

• Aflatoxins disproportionately impact the poor• Highly toxic strains, conducive environmental

conditions, traditional farming methods and improper grain drying and storage practices, unregulated markets

International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org


Aflatoxin Contamination in West Africa

• Maize: 4,000 – Benin• Peanut: 925 – Burkina• Sorghum: 80 – Ghana• Rice: 372 – Nigeria• Millet: 200 – Nigeria• Tiger nuts: 120 – Nigeria

Primary products• Peanut paste: 3,278 – Ghana• Peanut sauce: 943 – Ghana• Leaf sauce: 775 – Gambia• Maize dough: 313 – Ghana• Kenkey: 524 – Ghana• Cashew paste: 366 – Ghana• Peanut oil: 500 – Nigeria• Yam flour: 7,600 – Nigeria• Local beer: 135 – Nigeria• Infant food: 19* – Burkina

Food productsMTL = 10 - 20 ng/g


Aflatoxin and Human Health

Death Binds with DNA -- mutagenic Type I carcinogen Causes liver cancer – increasing incidence Aflatoxin interacts with HBV

• 30 times more potent in HBV+ people• 5-60 times higher cancer risk• 40% of liver cancer cases linked to aflatoxin

Associated with stunting in children Associated with immune suppression Impede uptake and utilization of micronutrients in

human systems Associated with Kwashiorkor in children Contributes to 40% of DALYs


Animal Health Impact of Aflatoxin

Livestock and poultry losses liver damage including cancer recurrent infection due to

immune system suppression reduced growth rate losses in feed efficiency decreased milk and egg yield embryo toxicity (reduced

reproductivity) death (cattle, turkey, poultry,

swine..)

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Aflatoxin and Poultry (Broilers)

Aflatoxin levels in feeds in Nigeria

Aflatoxin level (ppb) Samples (%)

<20 (safe) 38

>20 to 100 (up to 5x) 14

>100 to 500 (up to 25x) 41

>500 to 1,000 (up to 100x) 7

AF-free diet 500 ppb AF dietAF-freediet

500 ppb AF diet

~40% reduction in live weight (8 weeks)

EC 2007

Aflatoxin and Trade

SOURCE: EU Rapid Alert System For Food and Feed (RASFF, 2005)

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Trade Losses due to Aflatoxins

• Nigeria and Senegal major groundnut exporters in 1960s. Compliance has economic incentives

• Senegal: US$ 4.1 million added capital investment and 15% recurring cost would attract 30% price differential to oil cake.

• Export would increase from 25K tons to 210K tons.

• Increased export volume and price differential would annually add $281 million value to groundnut export for the capital investment.

• For confectionary groundnut, adherence to Good Management Practices would increase export value by US$ 45 million annually.

• Best quality exported; poorer quality consumed domestically. Peanut

Maize

Coffee

Cocoa

Groundnut Pyramids in Nigeria during 1960sPyramids in Egypt?

World Bank; Mbaye (2004)


Mycotoxin Projects in Burkina Faso

• 2007‐2010: Diffusion of cost‐effective technologies for the control of mycotoxin contamination for increased health and income in Burkina Faso, Tanzania and Mozambique

• 2010‐2014: Biological Control of Aflatoxins in Maize for Enhanced Food Safety and Income in Burkina Faso

Two projects – both funded by Austrian Development Cooperation


Biocontrol Project Outputs

• Output 1: Aflatoxin biocontrol strains identified for reduction of aflatoxins in maize and other associated susceptible crops.

• Output 2: Efficacy and product data available for pre‐registration of atoxigenic strains as biopesticides.

• Output 3: Students and staff trained for conducting aflatoxin research.

• Output 4: Infrastructure and technical capacity developed for aflatoxin research.


Atoxigenic Strain IdentificationCollection/characterization Toxin assay

Fieldefficacy

test

Labcompetitionassay

VCG/DNA characterization

cnxnia-D

Unknown 2

+


1. Strain Identification

• 3,660 Aspergillus isolates from 256 samples collected in three agro‐ecological zones of Burkina Faso.

• Four widely distributed and adapted atoxigenic strains, namely M109‐2, M110‐7, MO11‐8 and GO18‐2 identified.

• Biocontrol product Aflasafe BF01 constituted with the four strains mentioned above

Broadcast @ 10 kg/ha 2‐3 weeks before flowering

Sporulation on moist soil

Spores

Insects

Aflasafe in 2.5 & 5 kg bags

3‐20 days

Wind

Soilcolonization

30‐33 grains m‐2

How Does aflasafe Work?


Crop Sample Treatment FieldsAF

mean (ppb)*

Red uction(%)

Groundnut

HarvestTreated 51 3.7

92Control 51 44.0

StorageTreated 49 15.0

86Control 49 101.0

Maize

HarvestTreated 17 1.7

82Control 17 9.1

StorageTreated 17 50.3

84Control 17 319.0

*All means of aflasafe treated and control pairs significantly different; Student’s t-test (P<0.05)

Efficacy trial sites

Crop sampling sites

2. Efficacy of Aflasafe BF012012


3. Student/Staff Training

• An INERA staff (Mr. Touré Mahama)was trained in principles and methodologies followed in aflatoxin biocontrol research at IITA.

• Spent three months each for two years at IITA.

• MPhil student Mrs TIENDREBEOGO Assiata spent four months at IFA‐Tulln, Austria

• She worked on development of DNA‐based assays to monitor Aspergillus biocontrol strains in the field.


4. Infrastructure Development

• A lab renovated in INERA’s Farako Ba research station

• Lab equipped with Laminar flow hood, Autoclave, Coffee grinder, Water‐jacket incubator, Digital shaker, Neogen aflatoxin kits and LFD reader, and automatic pipettes

• The renovation of the building and the new equipment facilitated further research activities after the project ended


Next Steps

• A highly effective biocontrol product available • Disseminate Full registration of the product

necessary• Developed in partnership with farmers to

demonstrate product efficacy• Need for consultation with other stakeholders in

maize and groundnut value chains• Explore mechanisms for scaling up of the product –

public, private, mixed• Identify scaling up partners• Plan scaling up implementation


Aflasafe Manufacturing Facility

Large‐scale: capacity 5 tons/hour

CoolerRoaster

Inoculum Production Lab

Big WeigherSmall Weigher

Sealer Sealer

Sterilised Grain Silos50 tons each

Raw Grain Silo100 tons

Finished Product

Debearder

Fine Cleaner

Deabearder & Fine CleanerHousing

IntakePit

Roaster & Coolerhousing

2 Labs

IITA

TucsonUSDA/ARS

IITA, USDA, & Doreo have Teamed up to Bring Aflatoxin Prevention to Africa

Made Possible by Many National Partners in Ministries, Industry, and on the Farm

Nigeria

For more information about aflatoxin biocontrol for Africa, check out: www.aflasafe.com

Science

Importance of Aflatoxin: Summary of biocontrol projects in Burkina Faso