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The exopolysaccharide (EPS B3-15) and biosurfactant (BS B3-15), produced by the marine Bacillus licheniformis B3-15, were recently reported to possess different antibiofilm activities, with the EPS being more active in preventing the adhesion of Pseudomonas aeruginosa and Staphylococcus aureus and the BS in destroying their preformed biofilms on different surfaces. In this study, the synergistic effects of the two exopolymers on the bacterial adhesion and biofilm disruption of P. aeruginosa and S. aureus were evaluated on polystyrene, a medical polyvinyl chloride (PVC) device, and contact lenses (CLs) in order to address their potential use in biomedical applications. To this purpose, EPS B3-15 and BS B3-15 were equally combined (1:1 w/w), and the mixture (BPS B3-15) was added at different concentrations (from 50 to 300 µg mL−1) and at different times of bacterial development. Compared to each polymer, the BPS B3-15 (300 µg mL−1) more efficiently reduced the adhesion of P. aeruginosa and S. aureus on polystyrene (65 and 58%, respectively), PVC devices (62 and 42%, respectively), and CLs (39 and 35%, respectively), also in combination with a CLs care solution (88 and 39%, respectively). Furthermore, BPS B3-15 was able to disrupt mature biofilms, acting more effectively against S. aureus (72%) than P. aeruginosa (6%). The combination of exopolymers at low concentrations exhibited synergistic effects to prevent and eradicate biofilms. [ABSTRACT FROM AUTHOR]

We report the ability of the crude biosurfactant (BS B3-15), produced by the marine, thermotolerant Bacillus licheniformis B3-15, to hinder the adhesion and biofilm formation of Pseudomonas aeruginosa ATCC 27853 and Staphylococcus aureus ATCC 29213 to polystyrene and human cells. First, we attempted to increase the BS yield, optimizing the culture conditions, and evaluated the surface-active properties of cell-free supernatants. Under phosphate deprivation (0.06 mM) and 5% saccharose, the yield of BS (1.5 g/L) increased by 37%, which could be explained by the earlier (12 h) increase in lchAA expression compared to the non-optimized condition (48 h). Without exerting any anti-bacterial activity, BS (300 µg/mL) prevented the adhesion of P. aeruginosa and S. aureus to polystyrene (47% and 36%, respectively) and disrupted the preformed biofilms, being more efficient against S. aureus (47%) than P. aeruginosa (26%). When added to human cells, the BS reduced the adhesion of P. aeruginosa and S. aureus (10× and 100,000× CFU/mL, respectively) without altering the epithelial cells' viability. As it is not cytotoxic, BS B3-15 could be useful to prevent or remove bacterial biofilms in several medical and non-medical applications. [ABSTRACT FROM AUTHOR]

The surfactin-like lipopeptide (BS-SBP3) and the exopolysaccharide (EPS-SBP3) produced by the polyextremophilic Bacillus horneckiae SBP3 (DSM 103063) have been recently described as valuable biopolymers useful in biotechnological applications. To investigate the hydrating capabilities of BS-SBP3 and EPS-SBP3, here we evaluated (i) their wetting properties, measuring the contact angle; (ii) their moisture uptake abilities using the gravimetric method; and (iii) their hydrating states (from 0 to 160% w/w of water content) using ATR-FTIR spectroscopy. BS-SBP3 reduced the water contact angle on a hydrophobic surface from 81.7° to 51.3°, whereas the contact angle in the presence of EPS-SBP3 was 72.9°, indicating that BS-SBP3 improved the wettability of the hydrophobic surface. In the moisture uptake tests, EPS-SBP3 absorbed more water than BS-SBP3, increasing its weight from 10 mg to 30.1 mg after 36 h of 100% humidity exposure. Spectral distance and cross-correlation analyses were used to evaluate the molecular changes of the two biopolymers during the hydration process. As the water concentration increased, BS-SBP3 spectra changed in intensity in the two contributions of the OH-stretching band named "closed" and "open" (3247 and 3336 cm−1, respectively). Differently, the spectra of EPS-SBP3 exhibited a broader peak (3257 cm−1), which shifted at higher water concentrations. As evaluated by the spectral distance and the wavelet cross-correlation analysis, the OH-stretching bands of the BS-SBP3 and EPS-SBP3 changed as a function of water content, with two different sigmoidal trends having the inflection points at 80% and 48%, respectively, indicating peculiar water-properties of each biopolymer. As wetting agents, these biopolymers might replace industrially manufactured additives in agriculture and the food and cosmetic industries. [ABSTRACT FROM AUTHOR]

The exploitation of thermophilic hydrocarbon-utilizing bacilli could provide novel environmentally friendly surfactants. In this work, 80 thermophilic bacilli isolated from shallow hydrothermal vents of the Eolian Islands (Italy) were screened for their ability to utilize hydrocarbons and produce biosurfactants (BSs). Among them, 15 strains grew with kerosene or gasoline (2% v/v) as the only carbon and energy source, and most of them were positive to the methylene blue agar as prescreening assay for BSs production and displayed emulsifying activity. The cell-free supernatants (CFSs) from two selected strains, Bacillus licheniformis B3-15 and Bacillus horneckiae SBP3, were both surface active and able to emulsify different hydrocarbons and vegetable oils. BSs from B3-15 (910 mg L−1) and SBP3 (950 mg L−1) were chemically different surfactin-like lipopeptides, with specific mineral-, castor- and crude oil removal ability from the cotton matrix. CFSs from the 15 thermophilic strains, which harbor both lipolytic and surfactant abilities, could be suitable for industrial-based applications and environmental issues, such as oil recovery and removal from polluted areas or surfaces, (e.g., oil pipelines, bilge tankers, or industrial silos), whereas the crude BSs, as high-value compounds, may be used in different fields of application, as detergent, cosmeceutical, and pharmaceutical industries. [ABSTRACT FROM AUTHOR]