Abstract
Information on the microbiology of camel milk is very limited. In this work, the genetic characterization and proteomic identification of 13 putative producing bacteriocin Leuconostoc strains exhibiting antilisterial activity and isolated from camel milk were performed. DNA sequencing of the 13 selected strains revealed high homology among the 16S rRNA genes for all strains. In addition, 99% homology with Leuconostoc mesenteroides was observed when these sequences were analysed by the BLAST tool against other sequences from reference strains deposited in the Genbank. Furthermore, the isolates were characterized by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDITOF MS) which allowed for the identification of 2 mass peaks 6242 m/z and 5118 m/z that resulted to be specific to the species L. mesenteroides. Remarkably, the phyloproteomic tree provided more intraspecific information of L. mesenteroides than phylogenetic analysis. Accordingly, phyloproteomic analysis grouped L. mesenteroides strains into different subbranches, while all L. mesenteroides isolates were grouped in the same branch according to phylogenetic analysis. This study represents, to our knowledge, the first report on the use of MALDI-TOF MS on the identification of LAB isolated from camel milk.
Highlights
Increasing consumer demand for natural, healthy, and convenient foods has resulted in a new generation of minimally processed foods that focus on biopreservation, refrigeration, and packaging as hurdle strategies to extend the shelf-life of these products
While many studies have investigated the microbiology of cow, sheep, and goat’s milk, only a few studies have focused on the microbiology of camel milk
Other authors have reported the effectiveness of protective proteins from camel milk against bacteria, such as L. lactis subsp. cremoris, E. coli, S. aureus, Salmonella typhimurium, and rotavirus [16]
Summary
Increasing consumer demand for natural, healthy, and convenient foods has resulted in a new generation of minimally processed foods that focus on biopreservation, refrigeration, and packaging as hurdle strategies to extend the shelf-life of these products. The use of natural antimicrobial metabolites from lactic acid bacteria (LAB) has been determined to be one of the most promising strategies in minimal processing. Leuconostoc spp. and other LAB strains isolated from meat or dairy products produce bacteriocins that are active against the major food pathogen Listeria monocytogenes [2,3,4,5,6]. This activity was first observed in the 1950s, extensive studies on bacteriocins produced by Leuconostoc spp. have only been conducted in the last 25 years. The importance of Leuconostoc strains in the dairy industry is widely recognized; knowledge of their physiology and genetics is less developed than that of Lactococcus [7]
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