In vitro evaluation of bacteriocin-like inhibitory substances produced by lactic acid bacteria isolated during traditional Sicilian cheese making

Abstract

Bacteriocins are antimicrobial proteins produced by bacteria that inhibit the growth of other bacteria with a bactericidal or bacteriostatic mode of action. Many lactic acid bacteria (LAB) produce a high diversity of different bacteriocins. Bacteriocinogenic LAB are generally recognised as safe (GRAS) and useful to control the frequent development of pathogens and spoilage microorganisms. For this reason they are commonly used as starter cultures in food fermentations. In this study, the authors describe the results of a screening on 699 LAB isolated from wooden vat surfaces, raw milk and traditional Sicilian cheeses, for the production of bacteriocin-like inhibitory substances, by comparing two alternative methods. The antagonistic activity of LAB and its proteinaceous nature were evaluated using the spot-on-the-lawn and the well-diffusion assay (WDA) and the sensitivity to proteolytic (proteinase K, protease B and trypsin), amylolytic (a-amylase) and lipolytic (lipase) enzymes. The indicator strains used were: Listeria monocytogenes, Staphylococcus aureus, Escherichia coli, Salmonella enteritidis. A total of 223 strains (belonging to the species Enterococcus spp., Lactobacillus spp., Pediococcus spp., Streptococcus spp., Leuconostoc spp. and Lactococcus lactis) were found to inhibit the growth of Listeria monocytogenes by using the spot-on-the-lawn method; only 37 of these were confirmed by using the WDA. The direct addition of bacteriocin-producing cultures into dairy products can be a more practical and economic option for the improvement of the safety and quality of the final product.

Stability of Bacteriocin-Like Inhibitory Substance (BLIS) Produced byPediococcus acidilacticikp10 at Different Extreme Conditions

“…Bacteriocin-like-inhibitory substance (BLIS) is often interchangeably used with bacteriocin since BLIS is uncharacterised bacteriocin that apparently shares similar activity. Just like bacteriocin, BLIS activity can also be quantified by various methods such as agar well diffusion assay, spot-on-lawn assay, turbidimetric assay, ELISA, radiometry, conductance measurements, and bioassays based on self-induction skills [ 10 ]. However, determination method employing sensitive microorganisms to exhibit the growth inhibition potential of a bacteriocin is the most widely used assay.…”

Retrospective study on the hygienic quality of fresh ricotta cheeses produced in Sicily, Italy

“…Furthermore, all these species were found in other traditional ewes’ Sicilian cheeses (Gaglio et al , 2014a ; Guarcello et al , 2016 ) and wooden equipment employed for cheese manufacture (Scatassa et al , 2015 ). Some works showed the ability of these LAB species to produce bacteriocin-like inhibitory substances (BLIS) active against Listeria and other pathogenic bacteria and this allows to improve the safety, control the fermentation microbiota, speed maturation and increase the shelf life of the final cheeses (Macaluso et al , 2016 ; Scatassa et al , 2017 ).…”

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

“…LAB have recently gained growing interest due to their proteolytic activities and use as protective cultures (Tulini et al, 2016). Macaluso et al (2016) obtained 699 LAB strains isolated from traditional Sicilian cheese and raw milk. Listeria monocytogenes, Staphylococcus aureus, Escherichia coli, and Salmonella Enteritidis bacteria were used to investigate antimicrobial activity.…”