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Zinc oxide nanoparticles (ZnO NPs) were synthesized using barberry (Berberis vulgaris) extract via heating method. The effects of the amount of barberry extract (15–35 ml) and the reaction time (30–90 min) on the antibacterial (clear zone diameter, mm) and antioxidant (%) activities of the synthesized ZnO NPs were investigated by response surface methodology. Main reducing and stabilizing compounds of barberry extract were identified by gas chromatography and Fourier transform infrared spectroscopy. Spherical ZnO NPs with an average size of 20 nm were successfully fabricated at optimal synthesis conditions using 35 ml of barberry extract and 30 min reaction time. ZnO NPs were determined to have a zeta potential of –15.3 mV and an antioxidant activity of 28.8%. The antibacterial activity of fabricated ZnO NPs was tested againstStaphylococcus aureusand found to possess significant (p<0.05) inhibitory effect against this microorganism.

A bench scale submerged fermentation process was used to bioethanol produce using sugar beet molasses and Saccharomyces cerevisiae, as substrate and microbial strain, respectively. Effects of selenium amount on growth of S. cerevisiae and bioethanol production were evaluated. The obtained results indicated that growth of S. cerevisiae (manifested as turbidity intensity) in the samples containing 0, 5, 10, 15, 20 and 25 μg sodium selenite, during aerobic process, was 0.1707, 0.1678, 0.1679, 0.1664, 0.1627 and 0.160% a.u./h (after 14 h incubation), respectively. Statistical analysis based on compression test indicated that there were insignificant (p > 0.05) differences between growth rate of the yeast in the fermented samples containing S. cerevisiae and 5 to 25 μg selenium salt. Response surface methodology was utilized to evaluate effects of two fermentation parameters namely, amount of selenium (5-25 μg) and substrate brix (10-25°Bx) on the concentration (g/L) of produced bioethanol. Obtained results revealed that maximum bioethanol concentration (55 g/L) was achieved using 15 μg selenium and molasses with 25°Bx. Furthermore, results have also indicated that, without using selenium and using molasses with 25°Bx, bioethanol with concentration of 29 g/L was produced.