Identification of indigenous Lactobacillus isolated from artisanal Algerian dairy product by 16S rRNA Gene Sequencing and MALDI-TOF Mass Spectrometry

Abstract

El-klila, Jben, Rayeb and Lben are artisanal dairy products typical of the North African region. These products are considered a good source of nutrients and a vector par excellence of indigenous lactic acid bacteria with significant technological and therapeutic potential. In this study, fifty-two Lactobacillus isolates from traditional dairy products (El-Klila, Jben and Rayeb) from the Ain Sefra region (southwestern of Algeria) were identified by phenotypic, genotypic and MALDI-TOF mass spectrometry methods. Phenotypic characterization allowed dividing the isolates into two groups: 7.69% of isolates mesophilic and strict heterofermentative and 92.31% isolates mesophilic and optional heterofermentative. The isolates identification by sequencing 16S rDNA was performed using the universal primers w02 and w18. Comparing the sequences of the isolates with the GenBank database (NCBI) revealed a high percentage with five species of Lactobacillus. Of the 52 isolates, thirteen were identified as Lactobacillus paracasei, four isolates were L. brevis, five isolates were L. rhamnosus and ten isolates were L. plantarum. The lasting twenty isolates were related, at the same time, to the plantarum species and the pentosus species. The use of MALDI-TOF mass spectrometry confirmed the identity of 36 strains of Lactobacillus. Of the 20 isolates related to the plantarum / pentosus group by 16S rDNA, 50% were identified as L. plantarum. Finally, the results of the two combined methods allowed us to correctly identify 80.76% of the Lactobacillus isolates at the genus and species level. The analysis by MALDI-TOF SM has proved to be a very reliable, fast (less than an hour) and inexpensive tool for identifying native Lactobacillus species from artisanal dairy products. This method can constitute a major tool for the study of the microbial biodiversity of artisanal food products.