Evaluation of Anti-oxidant and Anti-biofilm Activities of Biogenic Surfactants Derived from Bacillus amyloliquefaciens and Pseudomonas aeruginosa.

Biosurfactants, the microbial originated surface active agents, can modify the physicochemical properties of surfaces and reduce the bacterial adhesion via changing bacterial adhesion interactions on surfaces. They were also able to block oxidative chain reactions and might show antioxidant properties. The goal of this study was to evaluate the antioxidant and antibiofilm activities of biosurfactants which were derived from two autochthonous biosurfactant-producing strains, Bacillus amyloliquefaciens NS6 (surfactin), and Pseudomonas aeruginosa MN1 (rhamnolipids). Their antioxidant activities were determined by ferric reducing antioxidant power (FRAP) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) methods. Ferric thiocyanate (FTC) assay was used for determination of their lipid peroxidation inhibition capacity. Their effect to reduce the adhesion of Streptococcus mutans on polystyrene surfaces and disruption of its pre-formed biofilms were also investigated. Our results indicated that surfactin showed higher antioxidant activity than rhamnolipids and showed relatively similar efficiency to BHA that suggests it as a good alternative for synthetic antioxidants. In other hand, rhamnolipid conditioned surfaces showed higher antiadhesive and antibiofilm activity in comparison with surfactin treated surfaces.

Production of Vitamin D3 Enriched Biomass of Saccharomyces Cerevisiae as A Potential Food Supplement: Evaluation and Optimization of Culture Conditions Using Plackett-Burman and Response Surface Methodological Approaches.

Vitamin D deficiency causes osteoporosis, osteopenia, fractures, rickets, and more recently is linked with some chronic illnesses such as cancer. Because of the safety and probiotic properties of the yeast Saccharomyces cerevisiae, we hypothesized that yeast cells enriched with cholecalciferol (vitamin D3) could represent a solution for prevention or treatment of vitamin D deficiency. In this study S. cerevisiae was used as a vitamin D3 accumulator for the first time and the optimal conditions for enrichment of S. cerevisiae were determined. The Plackett-Burman screening studies were used for selection of the most important factors affecting cholecalciferol entrapment. Response surface methodology was employed for optimization of cholecalciferol accumulation in S. cerevisiae cells by using Box-Behnken design. A modified quadratic polynomial model fit the data appropriately. The optimal points of variables to maximize the response were cholecalciferol initial concentration of 358021.16 IU/mL, tryptone concentration of 1.82 g/L, sucrose concentration of 7.13 % (w/v), and shaking speed of 140.46 rpm. The maximum amount of cholecalciferol in dry cell weight of S. cerevisiae was 4428.11 IU/g. The cholecalciferol entrapment in yeast biomass increased about two-folds in optimized condition which indicates efficiency of optimization.

Optimization of Culture Conditions for Enrichment of Saccharomyces cerevisiae with Dl-α-Tocopherol by Response Surface Methodology.

Designing enriched probiotic supplements may have some advantages including protection of probiotic microorganism from oxidative destruction, improving enzyme activity of the gastrointestinal tract, and probably increasing half-life of micronutrient. In this study Saccharomyces cerevisiae enriched with dl-α-tocopherol was produced as an accumulator and transporter of a lipid soluble vitamin for the first time. By using one variable at the time screening studies, three independent variables were selected. Optimization of the level of dl-α-tocopherol entrapment in S. cerevisiae cells was performed by using Box-Behnken design via design expert software. A modified quadratic polynomial model appropriately fit the data. The convex shape of three-dimensional plots reveal that we could calculate the optimal point of the response in the range of parameters. The optimum points of independent parameters to maximize the response were dl-α-tocopherol initial concentration of 7625.82 µg/mL, sucrose concentration of 6.86 % w/v, and shaking speed of 137.70 rpm. Under these conditions, the maximum level of dl-α-tocopherol in dry cell weight of S. cerevisiae was 5.74 µg/g. The resemblance between the R-squared and adjusted R-squared and acceptable value of C.V% revealed acceptability and accuracy of the model.