The high alcohol content in wine usually has a negative impact on its sensory properties, but can also affect the general health of the consumers. The possibility to reduce ethanol production in wines during fermentation involves the use of different yeast strains characterized by the increased production of fermentation by‐products (glycerol, 2,3‐butanediol, etc.) from the available sugar. The activity of these strains should not impair the sensory properties of the wine. In general, the use of genetically and evolutionarily (non‐GM) engineered Saccharomyces cerevisiae strains is still not close enough to commercial application, and therefore, it is unavailable for wine producers. Thus, the aim of this study was to examine the possibility of reducing the production of ethanol in wines using different selected yeast strains (S. cerevisiae, Saccharomyces bayanus, Torulaspora delbrueckii, and Metschnikowia pulcherrima) available at the market. The application of individual yeast and sequential inoculation for wine alcoholic fermentation was examined. The achieved effects were evaluated by determining the content of ethanol, as well as fermentation by‐products (glycerol and volatile acids) and aromatic components in wine samples. Depending on the strain/s used, a decrease in ethanol content of up to 0.9% v/v was recorded in comparison with fermentation by S. cerevisiae alone. The sensory analysis of produced wine showed significant differences in taste and flavor. The results of the experiment conducted at the laboratory level and with the use of sterile must were compared to the ones from the scale‐up experiment in real vinification conditions. The observed differences in the alcohol content of produced wines were significantly lower.

In the effort to overcome the increase in antimicrobial resistance of different pathogens, natural products from microbial sources appear to be the most favorable alternative to current antibiotics. Production of antimicrobial compounds is highly dependent on the nutritional conditions. Hence, in order to achieve high product yields, selection of the media constituents and optimization of their concentrations are required. In this research, the possibility of antimicrobial substances production using Bacillus subtilis ATCC 6633 was investigated. Also, optimization of the cultivation medium composition in terms of contents of glycerol, sodium nitrite and phosphates was done. Response surface methodology and the method of desirability function were applied for determination of optimal values of the examined factors. The developed model predicts that the maximum inhibition zone diameters for Bacillus cereus ATCC 10876 (33.50 mm) and Pseudomonas aeruginosa ATCC 27853 (12.00 mm) are achieved when the initial contents of glycerol, sodium nitrite and phosphates were 43.72 g/L, 1.93 g/L and 5.64 g/L, respectively. The results of these experiments suggest that further research should include the utilization of crude glycerol as a carbon source and optimization of composition of such media and cultivation conditions in order to improve production of antimicrobial substances using Bacillus subtilis ATCC 6633.

Ethanol is an important industrial chemical with emerging potential as a biofuel to replace fossil fuels. In order to enhance the efficiency and yield of alcoholic fermentation, combined techniques such as cells immobilization and media optimization have been used. The aim of this study was the optimization of sodium alginate concentration and glucose and yeast extract content in the media for ethanol production with immobilized cells of Saccharomyces cerevisiae. Optimization of these parameters was attempted by using a Box-Behnken design using the response surface methodology. The obtained model predicts that the maximum ethanol content of 7.21% (v/v) is produced when the optimal values of sodium alginate concentration and initial content of glucose and yeast extract in the medium are 22.84 g/L, 196.42 g/L and 3.77 g/L, respectively. To minimize the number of yeast cells "eluted" from the alginate beads and residual glucose content in fermented media, additional two sets of optimization were made. The obtained results can be used for further techno-economic analyses of the process to select the optimum conditions of the fermentation process for industrial application.