Medina has completed his predoctoral studies at the Instituto de la Grasa – CSIC obtaining his PhD from Seville University in 2008. He has carried out his postdoctoral studies at North Carolina State University. He has published more than 30 papers in reputed journals and 5 book chapter. His main research line is the biochemistry and microbiology of fermented vegetables, in particular products from olives, cucumbers and other fermented vegetables.
This works performs challenge tests to determine the survival of 4 food-borne pathogen species (Escherichia coli, Staphylococcus aureus, Listeria monocytogenes, and Salmonella enterica) in Aloreña de Málaga table olive brines. Microorganism survival was modeled “in vitro” using a log-linear model. Data revealed that the olive brine had a considerable antimicrobial activity against the four pathogenic microorganisms tested, even at pH level of 5.5 and salt concentration of 25 g/l. Among pathogenic species, S. aureus and especially E. coli were the most resistant microorganisms. This way, the final population was below detection limit for all pathogens assayed after 24 hours. Furthermore, studies carried out in real olive packaging confirmed these results. Initial population of inoculated microorganisms were rapidly inactivated in the first 24 hours and not detected after 48 hours. Partial Least Squares regression showed that the inhibition of microorganisms was related with the concentration of certain phenolic compounds, especially with EDA (dialdehydic form of decarboxymethyl elenolic acid), HyEDA (EDA linked to hydroxytyrosol), hydroxytyrosol 4-glucoside, and oleoside 11-methyl ester. Data obtained in the present study confirm the adverse habitats that olive environment provides for the growth of food-borne pathogenic microorganisms and ensure that table olives are safe for consumer`s health.
Antonio Benítez has a degree in Biology from Seville University. Currently is enjoining a spanish government grant for the realization of his doctoral thesis which focuses on the search for microorganisms with technological and probiotic properties. He has attended various national and international congresses and has published 2 papers in reputed journals. Recently, he has enjoyed a mobility grant from the spanish government for learning assembly techniques genomes and microbial diversity studies by massive sequencing techniques.
Table olive has been reported as splendid carrier of benificial microorganisms to the human body. However, scarce information is available about different ingredients used in the processing and packaging, such as salt and seasoning material. In this sense, we used an optimized Illumina 16S rRNA gene-based analysis protocol to decipher the bacterial profiles of different ingredients used during table olive elaboration (garlic, pepper, fennel, thyme and salt) and analysis of the ITS region for the yeast profile. Metagenomics data were analyzed by QIIME pipeline. The analysis of 16S rRNA gene showed that in salt the predominant genus of bacteria was Salinibacter (42.44 %) from Rhodothermaceae family, followed by other genus included in the archaea family Halobacteriaceae (21.06 %). It is also remarkable the presence of Enterobacteriaceae, highly represented in fennel (71.23 %), pepper (60.93%) and garlic (24.26 %) samples, meanwhile the most representative genus in garlic was Pediococcus (31.58%) from Lactobacillae family. The analysis of ITS region showed predominance of Pichia genus, being in pepper (68.66 %), salt (35.25 %), garlic (30.53 %) and to a lesser extend in fennel (2.55 %). It is also noteworthy the presence of the genera Candida in fennel (69.56 %). The use of this methodology open a new door to the knowledge of the microbiota associated to table olive processing, limited until the moment by the lack of specific culture media in mostly cases.