Acceleration effect of sodium selenite on yeast growth and fermentative capability.

None of the authors of this manuscript has any financial or personal relationship with other people or organizations that could inappropriately influence their work. Sodium selenite, the source of the selenium, was of high purity. Saccharomyces cerevisiae JS, JN and JW, isolated from brewer’s yeast powder, are used widely in selenium enrichment. Zygosaccharomyces rouxii F, FM and PC, isolated from soybean sauce and a residue of soya, are tolerant of a high salt concentration. All the stored strains were cultivated according to the procedure described by Shaokui et al. (2005) with minor modifications. Briefly, the culture media (YPD media) were treated at 121°C at 15 psi in an autoclave (Sterilizer SE-510, Yamato, Japan) for 15 min. After that, six stored strains were spread in the cooling sterilized solution with the same inoculation amount and incubated at 28°C in a reciprocal shaker (179 rpm) for 48 h, during which time the concentration of each strain was detected by a spectrophotometric method with a wavelength of 600 nm every four hours. In order to select the strains which have a better reproductive capacity, the yeast growth curve was then drawn according to the absorbance. At this stage, the strains of F and JS were selected to move forward a single step (data not shown), and their salt tolerance was also detected. The comparative result indicated that JS could develop in 10% of salt while F could tolerate 18% of salt (data not shown). This consequence agrees with the source of the two strains and F is suitable for use in pickles. A series of concentration gradients (0; 0.50; 3.0; 5.0; 8.0; 12; 15; 20; 25; 30; 40; 50 μg sodium selenite/mL nutrient solution) were chosen following the research data of Hart et al. (2011), Liguang et al. (2011) and Penglase et al. (2011), so that a primary range of sodium selenite additive amount could be determined. For this purpose, the selected strains were inoculated in the solid media (PDA Acceleration effect of sodium selenite on yeast growth and fermentative capability