​Application of MALDI-TOF Mass Spectrometry to Identify Lactic Acid Bacteria Isolated from Artisanal Dairy Products in Algeria

Abstract

Background: Artisanal dairy products are considered an affordable food source and are highly valued by Algerian consumers. Methods: In this study during the period from 2019 to 2020, phenotypic identification methods and protein analysis by MALDI-TOF MS were performed to identify lactic acid bacteria isolated from 19 sample and five types of artisanal dairy products collected in different Algerian regions (East, West, North, South). Results: A number of 250 strains were isolated, only those that showed the characteristics of lactic acid bacteria were identified by analysing their proteins, The results showed that the strains belong to different species of LAB namely: Lactobacillus fermentum (31.03%), Enterococcus faecium (24.14%), Lactobacillus plantarum (21.55%), Enterococcus faecalis (17.24%), Lactococcus lactis ssp lactis (4.31%), Lactobacillus paracasei and Lactobacillus paraplantarum (0.86%). Identification by MALDI-TOF MS was similar to that provided by phenotypic Characterization. This new technique that has been used is considered as an effective tool for rapid identification of food-associated lactic acid strains and has also been successfully extended to dairy isolates.

Quality Properties of Egyptian Bio-Hard Cheese

“…Lactobacilli bacteria may have created facultative anaerobic conditions in the cheese or produced lactic and organic acids, leading to a decrease in the pH of the growth environment, which inhibits the growth and sporulation of molds. Additionally, natural compounds with antifungal properties produced by The LAB can be used effectively as a bio-preservative to protect against the growth of phytopathogenic and food-spoilage fungi., as shown by the results of Nagy et.al., (2009) and Zabouri et al (2021). As in Table (4) all organoleptic parameters increased in control Ras and Bio-Ras cheese treatments by increasing the ripening period 30, 60 and 90 days.…”