Bacteriocins from lactic acid

bacteria and their potential

in the preservation of fruit

products

1

Muhammad Iqbal

Ph.D Scholar (Botany)

2nd Semester (13-arid-3283)

Contents

Introduction

Importance of studying LAB bacteriocins as an alternative in

fruit product preservation

Biotechnological approaches for the use of bacteriocins in

fruit products

LAB bacteriocins with potential in the preservation of fruit

products

Conclusion

2

Introduction

Bacteriocins are ribosomally synthesized and extracellularly release

antimicrobial peptides produced by bacteria that vary in structure,

biochemical properties, mode of action and spectrum of activity [1–

3]

The bacteriocins produced by lactic acid bacteria (LAB) are more

thoroughly characterized on account of their “food grade quality”

and industrial importance

These peptides are mainly active against bacteria and can inhibit

several food-borne spoilage and pathogenic microorganisms

3

Conti….

The interest in the use of bacteriocins as an alternative food

preservation method has increased with consumer demand for

fresh-tasting and better-preserved chemical free food products

Bacteriocins generally do not cause changes in food products and

can be used as an additional gradient in food processing, reducing

the intensity of traditional preservation methods, such as heat [1]

In this way, the increase in the consumption of fruit products [8]

and consumer demand for food products that maintain their

natural characteristics [9] make bacteriocins as great candidates to

be used for the preservation of fruit products.

4

Conti….

The use of bacteriocins as food additives is widespread, however,

little is known about its use in fruit products, especially in

minimally processed fruits [4,5,10]

In the few last years, fruit products have been increasingly

associated with food-borne pathogens and spoilage

microorganisms [11–16].

Several LAB bacteriocins have been characterized and their

potential as natural food preservatives has been demonstrated [4–

7]

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Importance of studying LAB bacteriocins as an

alternative in fruit product preservation

Bacteriocins could be used in this kind of products by using pure

bacteriocins as food additives or by the use of bacteriocinogenic

strains as starter cultures, protective cultures or co-cultures

Bacteriocins can ensure microbiological safety and also

contribute to maintain the nutritional properties of fruits

Results have previously shown that nisin, apart from its

antibacterial activity, also contributes to preserve the vitamin C

content of minimally processed mangoes and fruit juices [48,50]

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Biotechnological approaches for the use of

bacteriocins in fruit products

Some studies have shown the potential of semi or purified forms of

the bacteriocins to preserve fruit juices and pulps by direct addition

[6,7,10,18,50]. These products are generally thermally-processed,

therefore, it is important that the bacteriocins are heat-stable

One approach to use bacteriocins in the conservation of minimally

processed fruits is by incorporating these peptides in the packaging

material [48]

This is known as active packaging which, besides protecting the

product from external environment, inhibits microbial growth,

minimizing direct addition of preservatives

9

Conti.....

Bacteriocin-incorporated films avoid the risks of negative

interaction with the food components and can provide longer

preservation compared with the conventional addition directly

into the food [51].

This is a promising technology, as the majority of solid or

semisolid foods present high microbial growth on their surface

[56]

However, the information available on the use of active

packaging containing bacteriocins for the preservation of

minimally processed fruits is still limited [48].

10

Conti.....

Edible coatings added with bacteriocins could also be a great

alternative to preserve minimally processed fruits

Thin layers of biopolymers (carbohydrate, lipid or protein)

applied directly on the surface of whole or minimally processed

fruit,

prevent water loss

reduce respiration rates [57]

Also used as carriers of bioactive ingredients, such as

bacteriocins, to prolong shelf-life [20]

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Figure 1. Bacteriocins: Mode of action

13Figure 1. Bacteriocins: mode of action (Cotter et al., 2005) modified

after.

LAB bacteriocins with potential in the

preservation of fruit products

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Many bacteriocins have been used in the preservation of fruit

products such as;

Nisin

Enterocin AS-48

Bovicin HC5

Enterocin 416K1

Bificin C6165

Pediocin

Nisin

Nisin is the most studied and best characterized bacteriocin for

the preservation of fruit products. It is a bacteriocin produced by

strains of Lactococcus lactis subspecies lactic and consists of a

34-residue peptide

Nisin has been approved to be used in foods since 1988 by the US

Food and Drug Agency (FDA) [2]

It has been used in processed cheeses, dairy products and canned

foods [81], but its approval in fruit products is limited to certain

countries

This bacteriocin is thermostable and its activity is increased at

acidic pH [82]

15

Conti.....

Nisin is active against S. aureus, L. monocytogenes, Clostridium

and Bacillus spores and even inhibits some Gram-negative

bacteria [1,48,83]

This bacteriocin inhibited vegetative growth and spore outgrowth

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Bovicin HC5

Bovicin HC5 is a bacteriocin produced by strains of

Streptococcus bovis HC5, a rapidly growing Gram positive

bacterium

It exhibits stability at high temperatures and acidic pH and has

inhibitory activity against several strains of food-borne pathogens

and spoilage microorganisms, including L. monocytogenes,

Clostridium tyrobutyricum, B. cereus and B. thuringiensis

It also inhibits strains of LAB, such as Streptococcus,

Lactococcus, Enterococcus and Lactobacillus [6,7,18,92,98].

This bacteriocin showed effectiveness in preserving fruit juices

and pulps

Enterocin AS-48

Enterocin AS-48 is a 70-residue cyclic peptide produced byEnterococcus faecalis subsp. liquefaciens S-48, and consists of aglobular arrangement

Enterocin AS-48 shows a broad antimicrobial spectrum againstboth Gram-positive and Gram-negative bacteria and is also stableat high temperatures and active at acidic pH [99]

Spoilage and pathogenic microorganisms related to fruit products,such as S. aureus, L. monocytogenes, B. cereus andAlicyclobacillus sp., were efficiently inhibited by enterocin AS-48 [4,5,59,103–106]

Enterocin AS-48 was tested in canned pineapple juice, apple ciderand several fruit juices

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Enterocin 416K1

Enterocin 416K1 is a 5 kDa bacteriocin produced by strains of

Enterococcus casseliflavus 416K1 isolated from Italian sausages

This bacteriocin is stable upon heating at 90 C for 120 min and

storage at 4 C for 6 months, and has demonstrated strong

antibacterial activity [110]

Enterocin 416K1, alone or in combination, could be a feasible

solution to extend the shelf-life and to obtain the microbiological

safety of ready-to-eat vegetable and fruits [19]

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Bificin C6165

Bificin C6165 is produced by strains of Bifidobacterium animalis

subsp. animalis 6165 and has shown higher activity at acidic pH

and elevated temperatures

Bificin C6165 showed antimicrobial activity against several

strains of A. acidoterrestris, LAB strains and Gram positive

bacteria including S. aureus and Enterococcus faecium [58]

Bificin could also be tested to be used in edible coating or in the

matrix of plastic films used for packaging minimally processed

fruits

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Pediocin

The antibacterial peptide pediocin has 44 amino acid residues

and, as with nisin, is commercially available to be used in food

preservation [2,113]

This bacteriocin has stability over a wide pH range (3–9) and

heat-processing temperatures (65–121 C) [113]

Pediocin exhibits antibacterial activity against a wide spectrum of

food-borne pathogens and food spoilage Gram-positive bacteria

[114]

This bacteriocin has been extensively studied for its use in food

preservation, mainly for foods of animal origin [114–116]

Pediocin could also be used to produce antimicrobial films to

package minimally processed fruits 22

Other Bacteriocins

Some other examples of bacteriocins with these characteristics

are;

Pentocin

TV35b

Enterocin A5-11

Bacteriocin EF2019

Bacteriocins produced by strains of Pediococcus and Lactococcus

from the human intestine

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Conclusion

Considering the fact that some food-borne pathogenic and spoilage

microorganisms are very dangerous, the purification and

characterization of novel bacteriocins are of great relevance in

order to develop novel products and applications

The use of purified or semi purified preparations of bacteriocins as

food preservatives have legal implications

In order to be approved for commercial and industrial applications,

studies must be performed to provide detailed safety information

supported by toxicological data

Additionally, proof of efficacy in foods, description of

manufacturing process, as well as the safety levels should be

investigated25

Reference

Ana Andréa Teixeira Barbosa, Hilário Cuquetto Mantovani &

Sona Jain (2017): Bacteriocins from lactic acid bacteria and their

potential in the preservation of fruit products, Critical Reviews in

Biotechnology,

DOI: 10.1080/07388551.2016.1262323

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4033612/

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