Bacillus amyloliquefaciens-Derived Lipopeptide Biosurfactants Inhibit Biofilm Formation and Expression of Biofilm-Related Genes of Staphylococcus aureus.

Karolína Englerová,Vanda Hajdučková,Marián Maďar,Katarína Reiffová,Rastislav Mucha,Ján Király,Zdenka Bedlovičová,Eva Styková,Radomíra Nemcová

doi:10.3390/antibiotics10101252

Abstract

Biosurfactants (BSs) are surface-active compounds produced by diverse microorganisms, including the genus Bacillus. These bioactive compounds possess biological activities such as antiadhesive, antimicrobial and antibiofilm effects that can lead to important applications in combating many infections. Based on these findings, we decided to investigate the antibiofilm activity of BSs from the marine Bacillus amyloliquefaciens against Staphylococcus aureus CCM 4223. Expression of biofilm-related genes was also evaluated using qRT-PCR. Isolated and partially purified BSs were identified and characterized by molecular tools and by UHPLC-DAD and MALDI-TOF/MS. Bacillus amyloliquefaciens 3/22, that exhibited surfactant activity evaluated by oil spreading assay, was characterized using the 16S rRNA sequencing method. Screening by PCR detected the presence of the sfp, srfAA, fenD and ituD genes, suggesting production of the lipopeptides (LPs) surfactin, fengycin and iturin. The above findings were further supported by the results of UHPLC-DAD and MALDI-TOF/MS. As quantified by the crystal violet method, the LPs significantly (p < 0.001) reduced biofilm formation of S. aureus in a dose-dependent manner and decreased expression of biofilm-related genes fnbA, fnbB, sortaseA and icaADBC operon. Data from our investigation indicate a promising therapeutic application for LPs isolated from B. amyloliquefaciens toward prevention of S. aureus biofilm infections.

Highlights

Results obtained by MALDI-TOF/MS and HPLC methods confirmed that
Antimicrobial activity of LPs 3/22 against S. aureus in planktonic cells was determined by MIC
Results obtained by MALDI-TOF/MS and HPLC methods confirmed that B. amyloliquefa6 of 18 ciens 3/22 produces surfactin, fengycin and iturin A, the three families of lipopeptide biosurfactants

Summary

Introduction

Antibiotic resistance and nosocomial infections are becoming a major issue in medicines today. Aside from other factors, biofilms contribute to such a situation. Biofilms allow microorganisms to colonize tissues and organs and various medical instruments and equipment and significantly contribute to the development and spreading of nosocomial infections. Characteristic features of biofilm-producing microorganisms involve increased resistance against antimicrobials and disinfectants and the ability to resist the immune system of the host. Antibiotic (ATB) therapy of biofilm infections is very demanding and often insufficient and, these infections may become long-lasting and frequently regressive [1,2]

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