Maldi-tof mass spectrometry for the identification and detection of antimicrobial activity of lactic acid bacteria isolated from local cheeses

Abstract

On this study, 21 traditionally made cheeses were used. A total of 150 lactic acid bacteria (LAB) isolates were obtained from cheeses. 100 of them were identified at genus levels as Leunoconostoc (10), Lactobacillus (46) and Enterococcus (44) using biochemical tests. 71 strains were identified as Enterococcus durans (6), E. faecalis (18), E. faecium (24), E. italicus (2), Lb. brevis (1), Lb. paracasei (2), Lb. plantarum (1), Lactococcus lactis (3), Leuconostoc lactis (1), Leu. mesenteroides (11), and Streptococcus parauberis (2) at species levels using MALDO-TDF MS analysis. 10 of 100 isolates that showed antimicrobial activity were obtained from 21 samples of local cheeses. LAB strains were centrifuged to obtain supernatants in order to investigate two mechanisms. First, unprocessed supernatant was used to examine total antibacterial effect. Second, bacteriocins were obtained from LAB strains isolated using partial purification. The Kirby-Bauer Disk diffusion method was used to compare their antimicrobial activity against six pathogen. On conclusion, the bacteriocin produced from E. faecium shows higher antimicrobial activity than the others, and therefore, it can be used as a biological preservatives to extend shelf life.

A newly developed strain of Enterococcus faecium isolated from fresh dairy products to be used as a probiotic in lactating Holstein cows

“…After that, the strain was identified by matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) and 16S ribosomal DNA (rDNA) sequencing. The isolate was identified ( Figure 1 ) via the analysis of its total proteome in which a score with more than 1.7 indicates genus identification and a score with more than 2 is the confidence value at the species level ( 16 ).…”

Mihaliç Peynirlerinden İzole Edilen Propionibacterium Türlerinin MALDI-TOF MS ile Tanımlanması

“…and Enterococcus sp.. Quantitative information on the identified isolates from the samples is given in Table 1. Recently, a study investigating microbiota of local cheese from Turkey published similar results obtained by MALDI-TOF MS (Kanak & Yilmaz, 2018). Kanak (2018) specially focused on lactic acid bacteria and identified as Enterococcus durans (6), E. faecalis (18), E. faecium (24), E. italicus (2), Lb.…”

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

“…This last one goes along with our results in terms of the two species Lactobacillus paracasei ssp paracasei, Lactobacillus plantarum found in the sample "J'ben". However, Kanak and Yilmaz, (2019) have found that species of the genus Enterococcus were predominant in turkey artisanal cheese.…”