Biodiversité de la flore lactique autochtone de 3 produits laitiers fermentés de chèvre artisanaux au Liban
Résumé
Objectives
In Lebanon, the production of traditional fermented goat dairy products is carried out at small scale, and only in a limited number of production units. As a result, there is a real risk of extinction of these products and loss of corresponding microbial resources. The recovery, enhancement and valorization of their microbial ecosystems are becoming necessary and urgent. The aim of this work was to isolate and characterize representative strains of Lactic Acid Bacteria (LAB) of three Lebanese traditional fermented goat dairy products, namely "Ambriss", "Serdaleh" and "Labneh El Darff" and provide an overview of their microbial biodiversity. The first two are produced in an amphora or a jar from the regions of Bekaa and Chouf, respectively, by successive filling of raw goat milk, followed by whey evacuation and surface salt dressing..
Materials and Methods
14 samples of the fermented products and their respective raw materials (raw milk and Laban) were collected from 6 producers located in the selected regions. LABs were isolated by using convenient agar media and conditions to differentiate mesophilic and thermophilic lactobacilli, lactococci, streptococci, enterococci and fecal streptococci. Carbohydrate fermentation tests were carried out by using API 50CH strips. The identity of the isolates at species level was obtained by 16S DNAr sequencing.
Main Results
Mesophilic flora ranges between 2.3*104 - 3.3*107 CFU /mL and between 2.6*105 - 2.9*109 CFU/mL in raw milk and Laban dedicated for the production of "Ambriss" and "Serdaleh", and "Labneh El Darff" respectively. Milk LAB belonged mainly to Streptococcus parauberis and Enterococcus species. A significant difference of total counts was observed within and between the products, ranging 2.0*104 - 2.8*106 CFU/mL for "Ambriss", 5.5*105 - 1.3*106 UFC/mL for "Serdaleh" and 2.4*105 - 1.4*106 UFC/mL for Labneh. Preliminary results from “Ambriss” indicated that Enterococcus durans was the dominant species over Pedicocci and Lactobacilli. By contrast, Lactobacilli were dominant in “Serdaleh” with L. kefiri as representative species. The high levels of salinity (3.84%) and acidity (pH= 3.40) in “Serdaleh” compared to “Ambriss” might explain the difference between the two products. Finally as for "Laban" and "Labneh EL Darff", Lactobacilli were represented by L. plantarum.
Conclusion
Our study indicates that microbial ecosystems of "Ambriss", "Serdaleh", and "Labneh El Darff" differ significantly. This fact allowed us isolating various strains we plan to further study in order to define their technological properties for their use in dairy applications. Lastly, 16S Metagenomic analysis (in progress) will allow us to better characterize microflora diversity of these original products.