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Susceptibility to Bacteriocins in Biofilm-Forming, Variable Staphylococci Isolated from Local Slovak Ewes’ Milk Lump Cheeses
oleh: Andrea Lauková, Monika Pogány Simonová, Valentína Focková, Miroslav Kološta, Martin Tomáška, Emília Dvorožňáková
Format: | Article |
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Diterbitkan: | MDPI AG 2020-09-01 |
Deskripsi
Seventeen staphylococci isolated from 54 Slovak local lump cheeses made from ewes’ milk were taxonomically allotted to five species and three clusters/groups involving the following species: <i>Staphylococcus aureus</i> (5 strains), <i>Staphylococcus xylosus</i> (3 strains), <i>Staphylococcus equorum</i> (one strain) <i>Staphylococcus succinus</i> (5 strains) and <i>Staphylococcus simulans</i> (3 strains). Five different species were determined. The aim of the study follows two lines: basic research in connection with staphylococci, and further possible application of the bacteriocins. Identified staphylococci were mostly susceptible to antibiotics (10 out of 14 antibiotics). Strains showed γ-hemolysis (meaning they did not form hemolysis) except for <i>S. aureus</i> SAOS1/1 strain, which formed β-hemolysis. <i>S. aureus</i> SAOS1/1 strain was also DNase positive as did <i>S. aureus</i> SAOS5/2 and SAOS51/3. The other staphylococci were DNase negative. <i>S. aureus</i> SAOS1/1 and SAOS51/3 showed biofilm formation on Congo red agar. However, using quantitative plate assay, 12 strains out of 17 showed low-grade biofilm formation (0.1 ≤ A<sub>570</sub> < 1), while five strains did not form biofilm (A<sub>570</sub> < 0.1). The growth of all strains, including those strains resistant to enterocins, was inhibited by nisin and gallidermin, with high inhibition activity resulting in the inhibition zone in size from 1600 up to 102,400 AU/mL (arbitrary unit per milliliter). This study contributes to microbiota colonization associated with raw ewe’s milk lump cheeses; it also indicates bacteriocin treatment benefit, which can be used in prevention and/or elimination of staphylococci.