Biosurfaktanty (BSs), ako bioaktívne zlúčeniny produkované rodom Bacillus, majú schopnosť pôsobiť na rast a tvorbu biofilmu patogénnych mikroorganizmov, čo je možné využiť v boji proti mnohým infekciám. Cieľom tejto práce bola izolácia potenciálnych bakteriálnych producentov BSs a charakterizácia ich vlastností. U vybraného izolátu B. amyloliquefaciens 3/22 izolované a čiastočne purifikované BSs boli charakterizované z hľadiska chemického zloženia pomocou HPLC a MALDI-TOF/MS a bol testovaný ich účinok na adherenciu, tvorbu biofilmu, ako aj na disperziu biofilmu u Staphylococcus aureus. Pomocou RT-qPCR bola tiež analyzovaná expresia génov súvisiacich s tvorbou biofilmu. Zo vzoriek morskej vody a piesku boli izolované a selektované 4 izoláty, ktoré boli fenotypovo a genotypovo charakterizované ako B. amyloliquefaciens 4/9, 1/6K, 3/22 a B. subtilis 2/30. Izoláty v diskovo-difúznom teste inhibovali rast S. aureus CCM 4223, Bacillus cereus, Salmonella Typhimurium CCM 7205 a Escherichia coli O149F4, pričom veľkosť inhibičných zón bola kmeňovo špecifická. Bezbunkové supernatanty (CFS) izolátov preukázali silnú antibiofilmovú aktivitu (p<0,001) voči S. aureus CCM 3953. CFS s pH 4,57 – 5,46 významne inhibovali aj rast S. aureus CCM 3953, zatiaľ čo neutrálne CFS jeho rast neovplyvnili. Oil spreading a drop collapse testy preukázali u CFS silnú povrchovú aktivitu. PCR metódou a sekvenáciou boli identifikované gény zodpovedné za produkciu BSs lipopeptidového charakteru, konkrétne surfaktínu (sfp, srfAA), fengycínu (fenB, fenD) a iturínu (ituD). Uvedené zistenia boli podporené aj výsledkami chemickej analýzy. BSs 3/22 mali inhibičný efekt na tvorbu biofilmu S. aureus CCM 4223 počas ko-kultivácie, pričom jeho tvorba sa signifikantne znižovala (p<0,05; p<0,01; p<0,001) v závislosti od zvyšujúcej sa koncentrácie BSs 3/22 (0,47 – 30 mg/ml). Bolo zistené signifikantné zníženie (p<0,001; p<0,01; p<0,05) schopnosti buniek S. aureus CCM 4223 adherovať na steny jamiek po ošetrení jamiek BSs 3/22 s koncentráciou 30, 15 a 7,5 mg/ml. BSs 3/22 taktiež signifikantne redukovali (p<0,001; p<0,05) 24-hodinový biofilm S. aureus CCM 4223 pri koncentráciách 30 – 0,11 mg/ml. Metódou RT-qPCR bolo zistené, že subinhibičné koncentrácie BSs 3/22 (1,5; 0,15; 0,015 mg/ml) modulovali expresiu génov fnbA, fnbB, srtA, icaADBC, agrA u S. aureus CCM 4223.

Biosurfactants (BSs), as bioactive compounds produced by the genus Bacillus, have the ability to affect the growth and biofilm formation of pathogenic microorganisms, which can be used to fight many infections. The aim of this work was to isolate potential bacterial producers of BSs and characterize their properties. Isolated and partially purified BSs from B. amyloliquefaciens 3/22 were characterized for their chemical composition by HPLC and MALDI-TOF/MS and tested for their effect on adherence, biofilm formation as well as biofilm dispersion in Staphylococcus aureus. The expression of genes associated with biofilm formation was also analyzed by RT-qPCR. Four strains were isolated and selected from seawater and sand samples, which were phenotypically and genotypically characterized as B. amyloliquefaciens 4/9, 1/6K, 3/22 and B. subtilis 2/30. Isolates in the disk-diffusion assay inhibited the growth of S. aureus CCM 4223, Bacillus cereus, Salmonella Typhimurium CCM 7205 and Escherichia coli O149F4, with the strain specific size of the inhibition zones. Cell-free supernatants (CFS) of isolates showed strong antibiofilm activity (p<0.001) against S. aureus CCM 3953. CFS at pH 4.57 - 5.46 also significantly inhibited the growth of S. aureus CCM 3953, while neutral CFS did not affect its growth. Oil spreading and drop collapse tests showed strong surface activity in CFS. The genes responsible for the production of BSs of lipopeptide character, namely surfactin (sfp, srfAA), fengycin (fenB, fenD) and iturin (ituD), were identified by PCR method and sequencing. These findings were also supported by the results of chemical analysis. BSs 3/22 had an inhibitory effect on S. aureus CCM 4223 biofilm formation during co-cultivation, with its formation decreasing significantly (p<0.05; p<0.01; p<0.001) depending on increasing BSs 3/22 concentration (0.47 – 30 mg/ml). A significant reduction (p<0.001; p<0.01; p<0.05) was found in the ability of S. aureus CCM 4223 cells to adhere to the walls of the wells after treatment of the wells with BS 3/22 solution at 30, 15 and 7.5 mg/ml. BSs 3/22 also significantly reduced (p<0.001; p<0.05) the 24-hour S. aureus CCM 4223 biofilm at concentrations of 30 – 0.11 mg/ml. Subinhibitory concentrations of BSs 3/22 (1.5; 0.15; 0.015 mg/ml) were found by RT-qPCR to modulate the expression of the fnbA, fnbB, srtA, icaADBC, agrA genes in S. aureus CCM 4223.