Figure 5 Transmission electron microscopy
micrographs of untreated D . alaskensis (A and B), after treatment with a sub-MIC level of AMS H2O-1 crude extract (C and D); and after treatment with the MIC level of AMS H2O-1 crude extract (E and F). Bar = 3 μm (A); 1 μm (C, F); and 0.5 μm (B, D, E). Physico-chemical properties Physico-chemical analysis (Table 2) demonstrated that AMS H2O-1 lipopeptide extract is as effective as Cytoskeletal Signaling inhibitor surfactin to decrease surface and interfacial tensions; both molecules achieved similar results in the applied tests. However, AMS H2O-1 showed a much lower critical micellar concentration value than the surfactin produced by B. subtilis. Table 2 Physico-chemical properties (surface tension –ST, Interfacial tension – IT and critical
micellar concentration – CMC) of AMS H2O-1 and surfactin Product ST (mN/m) IT (mN/m) CMC(mg/L) Surfactin 26.8 ± 0.1 21.8 ± 2.8 83.7 ± 0.8 AMS H2O-1 27.1 ± 1.6 15.6 ± 1.4 27.6 ± 0.1 Surface conditioning analysis The results obtained from the contact angle measurements (Table 3) indicated that stainless steel AISI 304, stainless steel AISI 430, galvanized steel and polystyrene are hydrophobic according to their ΔG iwi values, which selleck chemicals llc classifies a surface as hydrophilic when its value is positive and hydrophobic when its value is negative. More negative values correspond to more hydrophobic surfaces, and more positive screening assay values correspond to more hydrophilic Resminostat surfaces [35]. When these four surfaces were conditioned with AMS H2O-1 lipopeptide extract, they became less hydrophobic. Carbon steel (control) is hydrophilic and became hydrophobic. The surfactin treatment also decreased the hydrophobicity of some of the surfaces; all of the metal surfaces became hydrophilic with this treatment, while the polystyrene maintained the same degree of hydrophobicity. Table 3 Energy properties of conditioned
surfaces including the total surface free energy, the Lifshitz-van der Waals component, the Lewis acid–base properties, the electron acceptor component, the electron donor component and the surface hydrophobicity SURFACE/TREATMENT γLW(mJ/m2) γ-(mJ/m2) γ+(mJ/m2) γAB(mJ/m2) γTOT(mJ/m2) ΔGlLw(mJ/m2) Control 42.02 2.68 0.85 −3.03 41 −98.7 AMS H2O-1 57.22 0.95 26.94 −10.11 47.11 −13.8 Surfactin 68.57 0.5 42.16 −9.19 59.39 23.7 Control 29.03 2.59 1.6 −4.07 24.96 −119.1 AMS H2O-1 47.08 0.04 14.03 −1.46 45.62 −51.0 Surfactin 62.71 0.63 54.11 −11.64 51.07 39.3 CARBON STEEL Control 75.55 2.81 40.71 −21.37 54.17 17.7 AMS H2O-1 64.68 3.5 7.68 −10.37 54.31 −81.0 Surfactin 71.69 1.5 49.77 −17.27 54.42 30.2 GALVANIZED STEEL Control 35.09 0.66 4.93 −3.61 31.48 −97.9 AMS H2O-1 16.69 1.24 43.14 −14.61 2.08 −6.8 Surfactin 49.71 1.72 64.89 −21.1 28.61 42.7 POLYSTYRENE Control 43.87 1.45 9.78 −7.53 36.34 −69.3 AMS H2O-1 62.1 1.07 18.77 −8.95 53.15 −32.1 Surfactin 48.01 0.37 8.96 −3.62 44.4 −70.
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