Research progress on carotenoid production by Rhodosporidium toruloides.

Carotenoids are natural lipophilic pigments, which have been proven to provide significant health benefits to humans, relying on their capacity to efficiently scavenge singlet oxygen and peroxyl radicals as antioxidants. Strains belonging to the genus Rhodosporidium represent a heterogeneous group known for a number of phenotypic traits including accumulation of carotenoids and lipids and tolerance to heavy metals and oxidative stress. As a representative of these yeasts, Rhodosporidium toruloides naturally produces carotenoids with high antioxidant activity and grows on a wide variety of carbon sources. As a result, R. toruloides is a promising host for the efficient production of more value-added lipophilic compound carotenoids, e.g., torulene and torularhodin. This review provides a comprehensive summary of the research progress on carotenoid biosynthesis in R. toruloides, focusing on the understanding of biosynthetic pathways and the regulation of key enzymes and genes involved in the process. Moreover, the relationship between the accumulation of carotenoids and lipid biosynthesis, as well as the stress from diverse abiotic factors, has also been discussed for the first time. Finally, several feasible strategies have been proposed to promote carotenoid production by R. toruloides. It is possible that R. toruloides may become a critical strain in the production of carotenoids or high-value terpenoids by genetic technologies and optimal fermentation processes. KEY POINTS: • Biosynthetic pathway and its regulation of carotenoids in Rhodosporidium toruloides were concluded • Stimulation of abiotic factors for carotenoid biosynthesis in R. toruloides was summarized • Feasible strategies for increasing carotenoid production by R. toruloides were proposed.

[Traditional Chinese therapy of tonifying the kidney and invigorating blood circulation reduces sperm DNA damage and improves natural pregnancy in infertile males].

OBJECTIVE: To study the effect of the traditional Chinese therapy of tonifying the kidney and invigorating blood circulation (TKIB) on male infertility. METHODS: Forty-two infertile males with abnormal DNA fragmentation index (DFI) were randomly allocated into a TKIB (n = 22) and a control group (n = 20), the former treated by TKIB with an oral Chinese medicinal prescription while the latter with oral tamoxifen tablets and vitamin E capsules, both for 3 months. Before and after treatment, we obtained the semen parameters and sperm DFI from the patients and followed them up for the outcomes of natural pregnancy. RESULTS: Compared with the baseline, the patients in both the TKIB and control groups showed significant increases after medication in sperm concentration (ï¼»36.82 ± 29.16ï¼½ and ï¼»34.56 ± 37.03ï¼½ vs ï¼»50.00 ± 39.16ï¼½ and ï¼»40.72 ± 47.37ï¼½ ×106/ml, P<0.05), the percentage of progressively motile sperm (PMS) (ï¼»20.62 ± 9.10ï¼½% and ï¼»21.25 ± 9.11ï¼½% vs ï¼»36.82 ± 13.45ï¼½% and ï¼»26.18 ± 10.60ï¼½%, P<0.05) and the percentage of morphologically normal sperm (MNS) (ï¼»1.28 ± 1.00ï¼½% and ï¼»1.48 ± 0.91ï¼½% vs ï¼»3.44 ± 1.33ï¼½% and ï¼»2.57 ± 1.32ï¼½%, P<0.05), but remarkably decreased sperm DFI (ï¼»29.07 ± 11.52ï¼½% and ï¼»24.43 ± 8.46ï¼½% vs ï¼»15.51 ± 11.31ï¼½% and ï¼»18.53 ± 10.44ï¼½%, P<0.05). The patients of the TKIB group exhibited an even higher total sperm motility and percentages of PMS and MNS than those of the control group (P<0.05) but no statistically significant difference from the latter in sperm concentration or DFI (P>0.05). Besides, the former achieved higher rates of natural pregnancy (18.2%) and live birth (18.2%) than the controls (15% and 10%) though neither with statistically significant difference (P>0.05). CONCLUSIONS: The traditional Chinese therapy of tonifying the kidney and invigorating blood circulation can reduce sperm DNA damage and improve the outcomes of natural pregnancy in infertile men.