Effects of directional adaptation on selenium tolerance and accumulation of heterotrophic Chlorella pyrenoidosa / 生物工程学报

Selenium (Se) is an essential trace element for organisms. Se deficiency will cause diseases such as Keshan disease and Kashin-Beck in human being, and huge loss to animal husbandry. Currently available Se supplements have such problems as low Se content, poor bioavailability, and poor safety. Chlorella pyrenoidosa can produce bioavailable and safe organic Se under suitable conditions, which is thus a promising Se supplement. Therefore, in this study, we tried to improve the Se tolerance and accumulation of C. pyrenoidosa by directional adaptation. To be specific, we gradually increased the concentration of Na2SeO3 in medium to domesticate C. pyrenoidosa and optimized the adapting time and concentration gradient of Na2SeO3 during the adaptation. The results showed that the adapted C. pyrenoidosa was more tolerant to Se and had stronger Se enrichment ability. In 5 L fermenter, the adapted strains could tolerate 40 mg/L Na2SeO3 and the synthesis rate of organic Se was 175.6% higher. Then, Se addition method in the 5 L fermenter was optimized. The result demonstrated that addition of Na2SeO3 at 40 mg/L during heterotrophic culture achieved the final dry weight of C. pyrenoidosa cells at 106.4 g/L, content of organic Se at 1 227 mg/kg, and synthesis rate of organic Se at 1.36 mg/(L·h). Compared with the reported highest cell density of 75 g/L and the highest organic Se content of 560 mg/kg, the corresponding figures in this study were 41.9% and 119.1% higher, respectively. In conclusion, directional adaptation can remarkably improve the Se tolerance and enrichment of C. pyrenoidosa.

Initial discussion about the promoted cellular immunologic effects of BCG by organic selenium / 重庆医科大学学报

Objective:To discuss the influence of organic selenium on the immune effect of Bacille Calmette-Guerin(BCG). Methods:C57BL6/J mice were randomized into 4 groups:"BCG+Se"mice group were intracutaneously inoculated with BCG and orally fed with yeast-based selenium(Se);BCG mice group were immunized with BCG intracutaneously;Se mice group were im- munized with normal sodium and fed orally with Se;control mice group were immunized with normal sodium and fed orally water without Se.The mice were sacrificed after 4weeks or 8weeks to isolate the spleen mononuclear cells.T lympholeukocyte proliferation testing(stimulation index,SI),cytotoxic T lympholeukocyte(CTL)function testing as well as levels of IL-2 and IFN-?and mRNA levels of granzyme B and perforin were employed to assess the effect of vaccine for Mycobacterium tuber- culosis.They were determined by MTT assay,ELISA assay and RT-PCR,respectively.Results:The levels of 6 detected items in"BCG+Se"group and BCG group were significantly different from those in the control group(P

EFFECTS OF SELENIUM-ENRICHED PROBIOTICS ON IMMUNITY AND ANTIOXIDATION FUNCTION IN MICE / 营养学报

Objective: To investigate the effects of selenium-enriched probiotics on immunity and antioxidation function in mice. Method: One hundred healthy KM mice, female and male in half, were randomly divided into control, sodium selenite, selenium-enriched yeast (Se yeast), selenium-enriched probiotics (Se probiotics) and probiotics groups. One milliliter of water, sodium selenite (2 ?g Se/ml), Se yeast (2 ?g Se/ml), Se probiotics (2 ?g Se/ml) or probiotics were respectively supplemented to five groups in oral (ig) every day. Whole experiment lasted for 28 d. During the experiment, immunity and antioxidation functions were measured respectively. Results: The activation of peritoneal macrophage and thymus index in Se probiotics group were significantly higher than those of other four groups. The spleen index of Se probiotics group was higher than that of control, sodium selenite and probiotics group. The spleen lymphocyte transformation rate in Se probiotics group was significantly or very significantly higher than that in control or probiotics group. In addition, blood GSH-Px and plasma SOD activity in Se probiotics group were significantly higher than those in control and sodium selenite group. Plasma MDA concentration in Se probiotics group was very significantly lower than that in control and sodium selenite group. Conclusion: Selenium-enriched probiotics supplementation could significantly enhance immunity and antioxidation function in mice.