Session Speaker

Lactic Olives: A New Source for Antibiotic Producing Against Human Deseases?
Cidália Fátima PERES
Portugal

Table olives are a traditional component of the Mediterranean diet and are largely consumed in the world. The primary role of one’s diet is to provide enough nutrients to fulfill body building and energy requirements, besides pleasing the sensory organs and assuring convenience, while providing a feeling of social satisfaction and well-being. Most traditionally fermented foods result from spontaneous fermentations of conventional plant materials, and are known to harbor a unique biodiversity – particularly of lactic acid bacteria (LAB), which produce metabolites against, and ecologically dominate over contaminating microflora that would otherwise eventually pose organoleptic and health hazards.

Despite their fastidiousness, Lactobacillus have been proven to act against pathogens mostly via synthesis of major products of primary metabolism (e.g. organic acids, ethanol and carbon dioxide), or by-products and other minor compounds (e.g. bacteriocins, cyclic dipeptides, reuterin and reutericyclin, hydrogen peroxide, acetaldehyde, diacetyl and acetoin, 3-hydroxylated fatty acids and polyaromatic compounds as phenyl-lactic and benzoic acids) and pyroglutamic acid.

Some of those LAB may in addition be able to survive passage through the gastrointestinal tract, and accordingly act against pathogens installed therein (e.g. in the stomach or in the small bowel, and eventually colonize the large bowel). Other possibilities that will likely exist, as previous experience with similar strains has typically indicated, are antimicrobial potential against other food-borne pathogens, e.g. Listeria monocytogenes, Salmonella enteritidis, Campylobacter spp. and Staphylococcus aureus, besides spoilage microorganisms, e.g. Pseudomonas aeruginosa and Escherichia coli. Those bacteria genera are responsible for human deseases, is such examples of human pathogens in which multiple resistances to antibiotics are commonly found.

The current study deals with the screening of antagonism activity among Lactic Acid Bacteria (LAB) isolated from fermented table-olives against Helicobacter pylori, Staphylococcus aureus, Listeria monocytogenes, Salmonella enteritidis, Campylobacter spp. Firstly, the aptitude of these 14 LAB strains was evaluated regarding their use as antibiotic activity. All bacteriocin producers are from genus Lactobacillus. Besides their GRAS (generally recognized as safe) status, all of them showed to withstand in vitro tests for the simulation of the digestion and displayed high levels of bile tolerance. Several human pathogenic strains were inhibited by LAB's diffusible metabolites, others than lactate. The inhibitory responses were strain-specific and independent of their antibiotic susceptibility pattern. The identification of the above described potential new antibiotics produced from those bacteria highlights the importance of fermented olives as a vast and unexplored resource of potentially useful anti-microbial producer strains.