Antiadhesive activity of the biosurfactant pseudofactin II secreted by the Arctic bacterium Pseudomonas fluorescens BD5

<p>Abstract</p> <p>Background</p> <p>Pseudofactin II is a recently identified biosurfactant secreted by <it>Pseudomonas fluorescens </it>BD5, the strain obtained from freshwater from the Arctic Archipelago of Svalbard. Pseudofactin II is a novel compound identified as cyclic lipopeptide with a palmitic acid connected to the terminal amino group of eighth amino acid in peptide moiety. The C-terminal carboxylic group of the last amino acid forms a lactone with the hydroxyl of Thr3.</p> <p>Adhesion is the first stage of biofilm formation and the best moment for the action of antiadhesive and anti-biofilm compounds. Adsorption of biosurfactants to a surface e.g. glass, polystyrene, silicone modifies its hydrophobicity, interfering with the microbial adhesion and desorption processes. In this study the role and applications of pseudofactin II as a antiadhesive compound has been investigated from medicinal and therapeutic perspectives.</p> <p>Results</p> <p>Pseudofactin II lowered the adhesion to three types of surfaces (glass, polystyrene and silicone) of bacterial strains of five species: <it>Escherichia coli, Enterococcus faecalis, Enterococcus hirae, Staphylococcus epidermidis, Proteus mirabilis </it>and two <it>Candida albicans </it>strains. Pretreatment of a polystyrene surface with 0.5 mg/ml pseudofactin II inhibited bacterial adhesion by 36-90% and that of <it>C. albicans </it>by 92-99%. The same concentration of pseudofactin II dislodged 26-70% of preexisting biofilms grown on previously untreated surfaces. Pseudofactin II also caused a marked inhibition of the initial adhesion of <it>E. faecalis, E. coli, E. hirae </it>and <it>C. albicans </it>strains to silicone urethral catheters. The highest concentration tested (0.5 mg/ml) caused a total growth inhibition of <it>S. epidermidis</it>, partial (18-37%) inhibition of other bacteria and 8-9% inhibition of <it>C. albicans </it>growth.</p> <p>Conclusion</p> <p>Pseudofactin II showed antiadhesive activity against several pathogenic microorganisms which are potential biofilm formers on catheters, implants and internal prostheses. Up to 99% prevention could be achieved by 0.5 mg/ml pseudofactin II. In addition, pseudofactin II dispersed preformed biofilms. Pseudofactin II can be used as a disinfectant or surface coating agent against microbial colonization of different surfaces, e.g. implants or urethral catheters.</p

RAINIER: A Simulation Tool for Distributions of Excited Nuclear States and Cascade Fluctuations

A new code has been developed named RAINIER that simulates the $\gamma$-ray decay of discrete and quasi-continuum nuclear levels for a user-specified range of energy, angular momentum, and parity including a realistic treatment of level spacing and transition width fluctuations. A similar program, DICEBOX, uses the Monte Carlo method to simulate level and width fluctuations but is restricted to $\gamma$-ray decay from no more than two initial states such as de-excitation following thermal neutron capture. On the other hand, modern reaction codes such as TALYS and EMPIRE populate a wide range of states in the residual nucleus prior to $\gamma$-ray decay, but do not go beyond the use of deterministic functions and therefore neglect cascade fluctuations. This combination of capabilities allows RAINIER to be used to determine quasi-continuum properties through comparison with experimental data. Several examples are given that demonstrate how cascade fluctuations influence experimental high-resolution $\gamma$-ray spectra from reactions that populate a wide range of initial states.Comment: 14 pages, 13 figures, Nuclear Instrumentation and Methods A, 201

Cost-effective rhamnolipid production by Burkholderia thailandensis E264 using agro-industrial residues

The agro-industrial by-products corn steep liquor (CSL) and olive mill wastewater (OMW) were evaluated as low-cost substrates for rhamnolipid production by Burkholderia thailandensis E264. In a culture medium containing CSL (7.5% (v/v)) as sole substrate, B. thailandensis E264 produced 175 mg rhamnolipid/L, which is about 1.3 times the amount produced in the standard medium, which contains glycerol, peptone, and meat extract. When the CSL medium was supplemented with OMW (10% (v/v)), rhamnolipid production further increased up to 253 mg/L in flasks and 269 mg/L in a bioreactor. Rhamnolipids produced in CSL+OMW medium reduced the surface tension up to 27.1 mN/m, with a critical micelle concentration of 51 mg/L, better than the values obtained with the standard medium (28.9 mN/m and 58 mg/L, respectively). However, rhamnolipids produced in CSL+OMW medium displayed a weak emulsifying activity when compared to those produced in the other media. Whereas di-rhamnolipid congeners represented between 90 and 95% of rhamnolipids produced by B. thailandensis E264 in CSL and the standard medium, the relative abundance of mono-rhamnolipids increased up to 55% in the culture medium containing OMW. The difference in the rhamnolipid congeners produced in each medium explains their different surface-active properties. To the best of our knowledge, this is the first report of rhamnolipid production by B. thailandensis using a culture medium containing agro-industrial by-products as sole ingredients. Furthermore, rhamnolipids produced in the different media recovered around 60% of crude oil from contaminated sand, demonstrating its potential application in the petroleum industry and bioremediation.This study was funded by PARTEX Oil and Gas, the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UIDB/04469/2020 unit and LABBELS – Associate Laboratory in Biotechnology, Bioengineering and Microelectromechanical Systems, LA/P/0029/2020, and the National Science Centre (Poland), under the scope of the project 2020/37/B/NZ9/01519.info:eu-repo/semantics/publishedVersio

Biomolecular interactions of lysosomotropic surfactants with cytochrome c and its effect on the protein conformation: A biophysical approach

The molecular interactions between two single-chain lysosomotropic surfactants DMM-11 (2-Dodecanoyloxyethyl)trimethylammonium bromide) and DMPM-11 (2-Dodecanoyloxypropyl)trimethylammonium bromide) with a small heme-protein (cytochrome c (cyt-c)) in Hepes buffer (pH = 7.4) were extensively investigated by surface tension, dynamic light scattering (DLS), circular dichroism (CD) and fluorescence spectroscopy in combination with molecular dynamic simulation techniques. The results demonstrated that surfactants can destroy the hydrophobic cavity of cyt-c, make the α-helical become loose and convert it into the β-sheet structure. The interactions between surfactants and cyt-c are mainly hydrophobic. Molecular modelling approaches were also used to gather a deeper insight on the binding of lysosomotropic surfactants with cyt-c and the in silico results were found to be in good agreement with the experimental ones. This study provides a molecular basis for the applications of protein-surfactant complexes in biological, food, pharmaceutical, industrial and cosmetic systemsPolish-Portugal Executive Program for years 2017–2018 sponsored by the Polish Ministry of Science and Higher Education and by the Portuguese Foundation for Science and Technology (FCT). Additionally, FCT supported the study under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684). T. Janek was supported by the National Science Centre, Poland, projects 2017/26/E/NZ9/00975 and 2018/02/X/NZ6/02201. L. R. Rodrigues acknowledges FCT for the grant SFRH/BSAB/142873/2018. E. J. Gudiña was supported by the grant UMINHO/BPD/39/2015 funded by FCT under the scope of the project UID/BIO/04469/2013info:eu-repo/semantics/publishedVersio

Effect of high pressure on surfactin production by Bacillus subtilis: implications for its application by the oil industry

Surfactin, a lipopeptide biosurfactant produced by Bacillus subtilis strains, exhibits extraordinary surface active properties, as well as stability at a wide range of temperatures and salinities, making it useful to replace the chemical surfactants in many industrial applications. The oil industry can take advantage of its application to increase the productivity of oil reservoirs, through a technology known as microbial enhanced oil recovery (MEOR). However, in order to make this technology advantageous from an economic point of view, the surfactin-producing strains must be able of growing and producing the biosurfactant inside the oil reservoirs. In this work, B. subtilis #573, isolated from an oil reservoir, was evaluated regarding its ability of producing surfactin under oxygen limited conditions at high pressure. A central composite design (CCD) was used to model the effect of pressure (3.8-46.2 bar) and temperature (35.3-46.7°C) on surfactin production. The results obtained demonstrated that pressure (in the range studied) did not exhibit a negative effect on surfactin production by this isolate, whereas temperatures higher than 45°C reduced its production. For most of the different combinations of pressure and temperature assayed, surfactin production was observed after 24 h, and the surface tension was reduced to values bellow 26.5 mN/m. At 41°C and 47 bar, B. subtilis #573 produced 31 ± 2 mg of surfactin per liter after 24 h, reducing the surface tension to 25.6 ±0.6 mN/m. These results were similar to those achieved at the same temperature at atmospheric pressure (26.0 ± 0.3 mN/m and 27 ± 3 mg surfactin/L). The surfactin produced in both cases exhibited a critical micelle concentration value around 15 mg/L, and the chemical characterization (through UHPLC-MS) demonstrated the production of similar percentages of the different surfactin isoforms (C12-, C13-, C14-, C15- and C16-surfactin) in both conditions. Finally, the applicability of B. subtilis #573 in MEOR was studied in sand-pack columns. In assays performed at 41°C and 47 bar, additional oil recoveries around 14% were obtained after 14 days in in situ assays. These results demonstrate the applicability of B. subtilis #573 in in situ oil recovery processes.info:eu-repo/semantics/publishedVersio

Trehalose Lipid Biosurfactant Reduces Adhesion of Microbial Pathogens to Polystyrene and Silicone Surfaces: An Experimental and Computational Approach

Rhodococcus fascians BD8, isolated from Arctic soil, was found to produce biosurfactant when grown on n-hexadecane as the sole carbon source. The glycolipid product was identified as the trehalose lipid with a molecular mass of 848 g mol−1. The purified biosurfactant reduced the surface tension of water from 72 to 34 mN m−1. The critical micelle concentration of trehalose lipid was 0.140 mg mL−1. To examine its potential for biomedical applications, the antimicrobial and antiadhesive activity of the biosurfactant was evaluated against several pathogenic microorganisms. Trehalose lipid showed antimicrobial activity against resistant pathogens. The largest antimicrobial activities of trehalose lipid were observed against Vibrio harveyi and Proteus vulgaris. The highest concentration tested (0.5 mg mL−1) caused a partial (11–34%) inhibition of other Gram-positive and Gram-negative bacteria and 30% inhibition of Candida albicans growth. The trehalose lipid also showed significant antiadhesive properties against all of the tested microorganisms to polystyrene surface and silicone urethral catheters. The biosurfactant showed 95 and 70% antiadhesive activity against C. albicans and Escherichia coli, respectively. Finally, the role and application of trehalose lipid as an antiadhesive compound was investigated by the modification of the polystyrene and silicone surfaces. The intermolecular interaction energy calculations were performed for investigated complexes at the density functional level of theory. The results indicate that the presence of aromatic moieties can be substantial in the stabilization of trehalose lipid-surface complexes. The antimicrobial and antiadhesive activities of trehalose lipid make them promising alternatives to synthetic surfactants in a wide range of medical applications. Based on our findings, we propose that, because of its ability to inhibit microbial colonization of polystyrene and silicone surfaces, trehalose lipid can be used as a surface coating agent

Efficient conversion of black cumin cake from industrial waste into lipopeptide biosurfactant by Pseudomonas fluorescens

Supplementary data associated with this article can be found in the online version at doi:10.1016/j.bej.2023.108981.Most biosurfactants are obtained using costly culture media, which limits their wider industrial use. In the present study, a low-cost culture medium, containing the agro-industrial residue black cumin cake, was developed for amphisin production by Pseudomonas fluorescens DSS73. By using black cumin cake as the substrate, not only was the production cost reduced but also a higher production yield was achieved. A Box-Behnken experimental design was applied to maximize lipopeptide biosurfactant production. The optimal conditions for amphisin production, such as black cumin cake (6.6%) and NaCl (8.0 mM) concentration, and cultivation time (6.5 days), were determined. Yield of amphisin production, performed in optimal conditions, reached 16.51 ± 0.49 g/L. Such high production has not been evidenced previously for Pseudomonas lipopeptide biosurfactants. Moreover, active utilization of the substrate, observed with the aid of scanning electron microscopy (SEM), documented by numerous holes and pitting on the black cumin cake surface, was confirmed. Finally, antifungal activity of amphisin against Aspergillus carbonarius was demonstrated. Hence, amphisin production by P. fluorescens was achieved with statistical optimization using an inexpensive agro-industrial by-product for the first time.This work was supported by the National Science Centre, Poland, project 2020/37/B/NZ9/01519. EJG would like to acknowledge the support of the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UIDB/04469/2020 unit, and by LABBELS – Associate Laboratory in Biotechnology, Bioengineering and Microelectromechanical Systems, LA/P/0029/2020.info:eu-repo/semantics/publishedVersio

Sustainable surfactin production by Bacillus subtilis using crude glycerol from different wastes

Most biosurfactants are obtained using costly culture media and purification processes, which limits their wider industrial use. Sustainability of their production processes can be achieved, in part, by using cheap substrates found among agricultural and food wastes or byproducts. In the present study, crude glycerol, a raw material obtained from several industrial processes, was evaluated as a potential low-cost carbon source to reduce the costs of surfactin production by Bacillus subtilis #309. The culture medium containing soap-derived waste glycerol led to the best surfactin production, reaching about 2.8 g/L. To the best of our knowledge, this is the first report describing surfactin production by B. subtilis using stearin and soap wastes as carbon sources. A complete chemical characterization of surfactin analogs produced from the different waste glycerol samples was performed by liquid chromatographymass spectrometry (LC-MS) and Fourier transform infrared spectroscopy (FTIR). Furthermore, the surfactin produced in the study exhibited good stability in a wide range of pH, salinity and temperatures, suggesting its potential for several applications in biotechnology.National Science Centre, Poland, project 2020/37/B/NZ9/ 01519. The Article Processing Charge (APC) was financed under the Leading Research Groups support project from the subsidy increased for the period 2020–2025 in the amount of 2% of the subsidy referred to in Art. 387 (3) of the Law of 20 July 2018 on Higher Education and Science, obtained in 2019. This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of the UIDB/04469/2020 unit and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020—Programa Operacional Regional do Norteinfo:eu-repo/semantics/publishedVersio

MUSiC : a model-unspecific search for new physics in proton-proton collisions at root s=13TeV

Results of the Model Unspecific Search in CMS (MUSiC), using proton-proton collision data recorded at the LHC at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb(-1), are presented. The MUSiC analysis searches for anomalies that could be signatures of physics beyond the standard model. The analysis is based on the comparison of observed data with the standard model prediction, as determined from simulation, in several hundred final states and multiple kinematic distributions. Events containing at least one electron or muon are classified based on their final state topology, and an automated search algorithm surveys the observed data for deviations from the prediction. The sensitivity of the search is validated using multiple methods. No significant deviations from the predictions have been observed. For a wide range of final state topologies, agreement is found between the data and the standard model simulation. This analysis complements dedicated search analyses by significantly expanding the range of final states covered using a model independent approach with the largest data set to date to probe phase space regions beyond the reach of previous general searches.Peer reviewe

Measurement of prompt open-charm production cross sections in proton-proton collisions at root s=13 TeV

The production cross sections for prompt open-charm mesons in proton-proton collisions at a center-of-mass energy of 13TeV are reported. The measurement is performed using a data sample collected by the CMS experiment corresponding to an integrated luminosity of 29 nb(-1). The differential production cross sections of the D*(+/-), D-+/-, and D-0 ((D) over bar (0)) mesons are presented in ranges of transverse momentum and pseudorapidity 4 < p(T) < 100 GeV and vertical bar eta vertical bar < 2.1, respectively. The results are compared to several theoretical calculations and to previous measurements.Peer reviewe