BacteriophageManagement of SalmonellaContamination of VineFruitsDr Alison Blackwell, APS Biocontrol Ltd.

The ProblemContamination of drying fruit

The Problem• The majority of vine fruits supplied to the UK

market are grown and dried in Turkey

• Advantages:• excellent quality• Established relationship with a large group of producers

• Disadvantages• a known risk of microbial contamination of the drying fruit;

e.g. through fouling by birds, reptiles & a variety of wildanimals and subsequent distribution during fruit handling

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The Problem• Salmonella is the most important foodborne-pathogen and concern to the dried-

fruit industry

• Salmonella may survive the stringent washing procedure post drying and continueundetected through the supply chain

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Retailpack

The Problem• Confirmed contamination issues are very rare but when they do occur they

can cause significant financial losses, with potential impacts on a supplier’sshare of a very competitive market

• Innovations put in place to de-risk the system would add confidence to thegrower, packer, retailer and also the consumer

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BacteriophageThe prefect biocontrol agents

Bacteriophage

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• Bacterial viruses• The most abundant organisms in the world (1013

on Earth)• For almost every bacterial species, there exists at

least one bacteriophage that can specifically infect& ultimately destroy that particular bacterialgroup

• Could bacteriophage act as effective biocontrolagents of microbial contaminants of dried fruit?

DNA

Baseplate

Tail fibres

Head(capsid)

Collar

Tailsheath

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Bacteriophage as biocontrols

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Bacteriophage as biocontrols

• Advantages over mainstreampesticides & biopesticides:• safe, naturally-occurring within the

pathogen’s environment• highly specific, reducing non-target risks

and potential environmental residueissues to zero

• rapid mode of action• applicable to both mainstream & organic

agriculture• continue to work long after chemicals

have lost their potency

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Commercialising BacteriophageAPS Biocontrol Ltd.

APS Biocontrol Ltd.• Innovative biocontrol company, developing technologies which address an

increasing need for effective and environmentally-sustainable replacementsfor synthetic chemicals

• The core technology is based on bacteriophage; naturally-occurring, safeantimicrobials

• The technology is being developed in a number of market sectors, with thelead product, Biolyse® being a world first; a bacteriophage-based solution foruse post harvest and in particular, for washed and packed fresh produce

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Reducing shelf-life losses: Biolyse®

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• A specific bacteriophage mix targetingspoilage pathogens on potatoes

• Marketed as a processing aid*

• Provides significantly greater control thanchemical products & addresses potentialissues associated with chlorate residues onfood

• UK customers: approx. 40% of the industry,supplying all of the major multiples

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* “…. any substance not consumed as a food by itself, intentionally used in the processing of raw materials, foods or their ingredients, to fulfil a certain technological purpose during treatment or processing, and which may result in theunintentional but technically unavoidable presence of residues of the substance or its derivatives in the final product, provided that these residues do not present any health risk and do not have any technological effect on the finishedproduct”

Reducing shelf-life losses: Biolyse®

Estima: packing + 7d Crombie Desiree: packing + 2d

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Dried Fruit ContaminationBacteriophage as a solution?

Tackling Salmonella contamination of dried fruit

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BacteriophageIsolation

Bacterial LibraryCreation

Laboratory Assays Bacteriophage Scale-up

Factory & drying-mat applications

DisseminationBacteriophageCharacterisation

Exploitation

Progress to date

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• 22 distinct Salmonella isolates recovered from 35 batches of fruit• Identified by PCR to two distinct serovars:

• S. enterica ssp diarizonae – sheep/reptile isolate• S. enterica ssp. salamae Clifton – reptile isolate

Typical Salmonella

Progress to date• Bacteriophages can be recovered from many

different environmental niches

• An environmental sample (fruit wash water, sheep orreptile faeces, sewage) is incubated in culture withthe bacterial host

• Bacteriophage presence within the sample isindicated by clear plaques representing bacterial lysis

• A library of 42 bacteriophage active against theSalmonella isolates has been created• 4 bacteriophage with the broadest activity spectrum (50% of

Salmonella isolates) selected for efficacy trials

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Trial bacteriophage mix composition

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HEAD

TAIL

TAILFIBRES

SIPHOVIRIDAE

HEAD

TAILNECK

TAIL FIBRES

MYOVIRIDAE

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Combining bacteriophage increases activity

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0,001

0,01

0,1

1

10

0 21 43 64 85 107

128

149

170

192

213

234

256

277

298

320

341

362

383

405

426

447

469

490

511

533

554

575

596

618

OD

600

Culture time (min)

4-phage mix vs mixed hosts

4-phage mix Host control

0,001

0,01

0,1

1

10

0 32 64 96 128

160

192

224

256

288

320

351

383

415

447

479

511

543

575

607

OD

600

Culture time (min)

Single phage vs single host

Phage 1 Phage 2 Phage 3 Phage 4 Host control

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The Next StepsIn situ trials

In situ trials

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A. Misted onto drying fruit

B. Applied as an emulsion in the oil coatingpost washing and processing in the factory

Conclusions

Conclusions

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• Bacteriophage have significant potential to act as effective biocontrolagents to de-risk the dried-fruit industry from potential microbialcontamination issues, particularly by Salmonella

• Bacteriophage extreme sensitivity is an advantage re. environmentalimpact issues but presents technical challenges for developing effectivemixes which will also cope with different pathogen serovars

• APS has a track record of commercialising bacteriophage for freshproduce and processes are in place to develop effective treatments fordrying vine fruits

• The technology is also suitable for other fruit and nut productssusceptible to bacterial contamination

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Contact detailsDr Alison BlackwellAPS Biocontrol Ltd.Prospect Business CentreDundee Technology ParkDundee, DD2 1TYUK+44 1382 561 696 / +44 7876 495 737ablackwell@apsbiocontrol.com

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