No abstract

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 chromatography–mass 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.

Many efforts have been made either to provide the typical three-dimensional (3D) printing materials with new and specific properties or to enhance their overall stability. The use of nanomaterials in 3D printing is gaining attention due to the tremendous functionality that this approach provides for those materials. This article presents a method of producing poly(lactic acid) (PLA)silver nanoparticle antibacterial filament for additive manufacturing. Polymer dope of silver salts within PLA was prepared by the solution-phase and solvent-less methods, followed by extrusion into filaments. Silver nanoparticles were synthesized in situ by thermal decomposition of silver salt during the thermal extrusion of the filament. The formation and dispersion of the nanoparticles within the polymer structure were examined and confirmed with transmission electron microscope and X-ray diffraction. The solution-phase method proposed in this study may prevent failure with nanoparticle dispersion occurring in melt blending. The filament was used for the fabrication of predesigned specimens for antimicrobial and mechanical testing. Printed objects exhibited antimicrobial activity against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. This study revealed that the incorporation of silver nanoparticles (0.01-5 wt%) into PLA does not significantly change its bulk properties but renders the composite antibacterial. The

Fourteen strains of Candida famata and 7 strains of C. sphaerica originating from blue-veined Rokpol cheese were studied for their ability to produce killer toxins against 3 strains of Yarrowia lipolytica selected as potential starter cultures for cheesemaking. All tested strains revealed killer activity in the presence of salt, at 14 degrees C and pH 4.6. Only one Y. lipolytica strain was resistant to C. famata and C. sphaerica killer toxins.

Yarrowia lipolytica is an early diverging species of the Saccharomycotina subphylum, which is recognized as a valuable host for many biotechnological applications exploiting its oleaginous capacities. The 20.5-Mb genome of the Polish Y. lipolytica strain A-101 will greatly help decipher the genetic basis of the regulation of its lipid metabolism.