Rita Rahmeh

ANTIMICROBIAL ACTIVITY OF

LACTIC ACID BACTERIA AND

ANTIMICROBIAL PEPTIDES FROM

CAMEL MILK

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The Microbiome Confers Health Benefits

Probiotics

“Live microorganisms that, when administered in

adequate amounts, confer a health benefit on the host”

(International Scientific Association for Probiotics and

Prebiotics).

Molecules that have broad activity to directly kill

bacteria, yeasts, fungi, and viruses.

Bacteriocins: produced by lactic acid bacteria

Antimicrobial

peptides

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The microbiome of bovine and non-bovine

milk is dominated by lactic acid bacteria

Reducing:

•Antibiotic resistant bacteria

•Economic losses

•Negative impact on human health

Commercialization

Microbiome Research Impacts Commercialization

3•2015, probiotic market $33.19 billion

•2020, expected to reach $46.55 billion

Probiotics

Research

Animal Production Food Preservation

Bacteriocins

Probiotics

Bacteriocins

Chicken or Turkey

feed

Campylobacter

Salmonella

Probiotics Improve Feed and Food

Feed Improvement

Food Improvement

Nisin A Nisaplin

Bacteriocin

Commercial food

preservative

50 countries (U.S. and

EU)

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Camel Milk as a Natural Source of Probiotics

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•Nutritional value

•Health benefits (boosts the immune system, aids in

preventing diabetes and anemia, helps in reducing allergy

such as lactose intolerance, etc.)

•Worthy of attention internationally

•Source of novel antimicrobial peptides

Objective: Isolate Probiotics from Camel Milk

Lactic acid bacteria

Food technology

Food preservatives

Bacteriocins

Farms

Feed additives

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Lactic acid bacteria isolation

Isolation and Characterization of Lactic Acid Bacteria

Gram Staining

Characterization of lactic acid bacteria

Gram-Positive Gram-Negative

Catalase

2 H2O2 2 H2O + O2

Catalase Test

Genus Species

Enterococcus

Enterococcus faecium

Enterococcus gallinarum

Enterococcus durans

Lactococcus

Lactococcus lactis

Lactococcus garvieae

Lactococcus brevis

Pediococcus

Pediococcus pentosaceus

Pediococcus acidilactici

Lactobacillus

Lactobacillus reuteri

Lactobacillus fermentum

Lactobacillus salivarius

Lactobacillus plantarum

Weissella

Weissella confusa

Weissella sp. t4r2c13

Leuconostoc

Leuconostoc pseudomesenteroides

Streptococcus

Streptococcus infantarius

Seven Genus of Lactic Acid Bacteria Were Identified

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Rahmeh et al., Probiotics and Antimicrobial Proteins (submitted)

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Inoculate the agar plate with a spot of lactic acid bacteria

Incubate at the growth conditions of lactic acid bacteria

Add second layer of agar inoculated with pathogen

Incubate at the growth conditions of pathogen

Lactic Acid Bacteria Exhibit Inhibitory Activity

Spot-on-the-lawn method

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Salmonella enterica ATCC 13076

Escherichia coli ATCC 25922

Staphylococcus aureus ATCC 25923

Staphylococcus epidermidis ATCC 12228

Listeria monocytogenes ATCC 7644

Shigella ATCC 12022

Pseudomonas aeruginosa CUGG 060519

Multi Drug Resistant Salmonella10

Pathogens causing human, animal diseases and food spoilage

28 Lactic Acid Bacteria Exhibit Inhibitory Activity

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Inoculate the agar plate with pathogen

Fill the wells with the cell-free supernatant of lactic acid bacteria

Incubate at the growth conditions of pathogen

Four Lactic Acid Bacteria Produce Bacteriocins

Agar diffusion method

Listeria monocytogenes ATCC

7644

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0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

0

100

200

300

400

500

600

Volume (mL)

Ab

so

rban

ce a

t 280 (

mA

U)

Gel filtration using Superdex 75 10/300 GL

17.9 ml-18.9 ml

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Purification of Bacteriocins

Rahmeh et al., J Dairy Sci. 2018 Jun;101(6):4944-4952

Treatment Antimicrobial Activity

of Bacteriocin

Enzymes

Control ++

α-chymotrypsin -

Proteinase K -

Papain -

Trypsin -

Protease -

pH

Control ++

2 ++

6 ++

8 ++

10 ++

Heat/Time

Control ++

37°C/180 min ++

60°C/60 min ++

80°C/60 min ++

100°C/30 min +

121°C/15 min +

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Characterization of Bacteriocins

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Microbiome of camel milk is a promising source of probiotics

Food preservatives

Feed Additives

Improvement in Food and Feed Production

Application Challenges in The Food System

Probiotics:

•The growth of lactic acid bacteria or the production of

bacteriocins are affected by pH, temperature fluctuation

during food processing, etc.

•Other bacterial fermenters co-inoculated negatively impact

bacteriocins production and biopreservation

Bacteriocins

The efficacy of pure bacteriocins is affected by:

• pH of the food matrix which influences its solubility

•Enzymes that inactivate the bacteriocins

•Food additives (spices and salt) which greatly reduce its

efficacy

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Thank you

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