Bio-guided Purification and Mass Spectrometry Characterisation Exploring the Lysozyme-like Protein from Enterococcus lactis Q1, an Unusual Marine Bacterial Strain Olfa Ben Braïek 1,2 & Slim Smaoui 3 & Yannick Fleury 4 & Stefano Morandi 5 & Khaled Hani 6 & Taoufik Ghrairi 1,2 Received: 11 June 2018 /Accepted: 10 September 2018/ # Springer Science+Business Media, LLC, part of Springer Nature 2018 Abstract Lactic acid bacteria produce various antibacterial peptides such as bacteriocins that are active against pathogenic and spoilage microorganisms. Very little attention has been paid to the production of lysozyme as an antimicrobial enzyme. The present work represents one of the few studies reporting lysozyme production by enterococci. Indeed, this study was first conducted to evaluate the antimicro bial activity of Enterococcus lactis Q1, an enterocin P-producing strain previously isolated from fresh shrimp (Penaeus vannamei), against multidrug-resistant clinical isolates. Results showed significant inhibitory activity (P < 0.05) towards diverse pathogens. The purification of the antimicrobial substances produced by Q1 strain leads to the isolation of two active fractions. The SDS-PAGE and mass spectrometry analyses of fraction number 2 (fraction 2) revealed the presence of a protein with molecular mass of 14.3 kDa. Additionally, the experimental results are consistent with mass spectra of industrial lysozyme (Fluka ref. 62970). The lysozyme produced by Enterococcus lactis Q1 strain was confirmed by a plate method against Micrococcus luteus ATCC 4698. Also, sensitivity of the Q1 strain to different concentrations of lysozyme was investigated. For the first time, this study shows that E. lactis Q1 produces lysozyme which could be an excellent candidate in food biopreservation or production of functional foods to promote health benefits. Keywords Antimicrobial activity . Enterococcus lactis . Lysozyme . Mass spectrometry . RP-HPLC Applied Biochemistry and Biotechnology https://doi.org/10.1007/s12010-018-2886-0 Highlights ● Antimicrobial activity of Enterococcus lactis strain Q1 against multidrug bacteria ● Purification of E. lactis strain Q1 using two-step procedure ● Detection of significant production of lysozyme by E. lactis Q1 ● This work is the first report on lysozyme production and purification in E. lactis ● E. lactis Q1 is a good candidate in food biopreservation or in antibiotherapy * Olfa Ben Braïek olfa.benbraiek@fst.utm.tn Back Affiliation