RESUMEN
Semen quality is one of the most important factors for the success of artificial insemination which has been widely applied in swine industry to take the advantages of the superior genetic background and higher fertility capability of boars. Hydroxytyrosol (HT), a polyphenol, has attracted broad interest due to its strong antioxidant, anti-inflammatory, and antibacterial activities. Sperm plasma membrane contains a large proportion of polyunsaturated fatty acids which is easily impaired by oxidative stress and thus to diminish semen quality. In current investigation, we aimed to explore the effects of dietary supplementation of HT on boar semen quality and the underlying mechanisms. Dietary supplementation of HT tended to increase sperm motility and semen volume/ejaculation. And the follow-up 2 months (without HT, just basal diet), the semen volume was significantly more while the abnormal sperm was less in HT group than that in control group. HT increased the "beneficial microbes" Bifidobacterium, Lactobacillus, Eubacterium, Intestinimonas, Coprococcus, and Butyricicoccus, however, decreased the relative abundance of "harmful microbes" Streptococcus, Oscillibacter, Clostridium_sensu_stricto, Escherichia, Phascolarctobacterium, and Barnesiella. Furthermore, HT increased plamsa steroid hormones such as testosterone and its derivatives, and antioxidant molecules while decreased bile acids and the derivatives. All the data suggest that HT improves gut microbiota to benefit plasma metabolites then to enhance spermatogenesis and semen quality. HT may be used as dietary additive to enhance boar semen quality in swine industry.
RESUMEN
p-Coumaric acid (p-CA) is a bioactive natural product and an important industrial material for pharmaceuticals and nutraceuticals. It can be synthesized from deamination of L-tyrosine by tyrosine ammonia lyase (TAL). In this work, we discovered two aromatic amino acid lyase genes, Sas-tal and Sts-tal, from Saccharothrix sp. NRRL B-16348 and Streptomyces sp. NRRL F-4489, respectively, and expressed them in Escherichia coli BL21(DE3). The two enzymes were functionally characterized as TAL. The optimum reaction temperature for Sas-TAL and Sts-TAL is 55 °C and 50 °C, respectively; while, the optimum pH for both TALs is 11. Sas-TAL had a kcat/Km value of 6.2 µM-1 min-1, while Sts-TAL had a much higher efficiency with a kcat/Km value of 78.3 µM-1 min-1. Both Sts-TAL and Sas-TAL can also take L-phenylalanine as the substrate to yield trans-cinnamic acid, and Sas-TAL showed much higher phenylalanine ammonia lyase activity than Sts-TAL. Using E. coli/Sts-TAL as a whole-cell biocatalyst, the productivity of p-CA reached 2.88 ± 0.12 g (L h)-1, which represents the highest efficiency for microbial production of p-CA. Therefore, this work not only reports the identification of two new TALs from actinomycetes, but also provides an efficient way to produce the industrially valuable material p-CA.
