Construction and optimization of cordycepin-producing Saccharomyces cerevisiae / 生物工程学报

Cordycepin is the key active component of medicinal fungus Cordyceps militaris, and it shows multiple functional activities such as anti-tumor and anti-virus. Cordycepin was conventionally produced by liquid fermentation of C. militaris, but the long production cycle and the low productivity constrained its development and application. In this study, two key genes for cordycepin biosynthesis (ScCNS1 and ScCNS2) were introduced into Saccharomyces cerevisiae S288C, producing 67.32 mg/L cordycepin at 240 h. Analysis of gene expression profiles indicated that ZWF1, PRS4, ADE4, ScCNS1 and ScCNS2 which encode enzymes involved in pentose phosphate pathway, purine metabolism and cordycepin biosynthesis pathway, were significantly up-regulated in the late phage of fermentation. Optimization of fermentation medium determined that 50 g/L initial glucose followed by feeding, supplemented with 5 mmol/L Cu²⁺ and 1.0 g/L adenine were the best condition. Fed-batch fermentation using the engineered yeast in a 5 L stirred fermenter produced 137.27 mg/L cordycepin at 144 h, with a productivity up to 0.95 mg/(L·h) reached, which was 240% higher than that of the control.

Ethnic distribution characteristics of SNPs associated with micronutrient deficiency risk of Chinese primary and middle school students / 中国学校卫生

Objective@#To explore ethnic distribution characteristics of SNPs associated with micronutrient deficiency risk of Chinese primary and middle school students, and to provide a basic reference for evaluating the risk of lack in micronutrient.@*Methods@#Totally 143 SNPs reported in previous studies were collected, and DNA was exacted by using magnetic beads in frozen blood cell samples from the 2016 nutrition health survey project of 1 130 primary and middle school students, competitive allele method was used to detect SNP genotyping. GO significant enrichment analysis R software package to PCA, kinship and linkage disequilibrium analysis were used for analysis of features of candidate SNPs. If there was a population structure, the FaST-LMM model was used for correlation analysis.@*Results@#The GO significant enrichment results showed that differentially expressed genes were mainly enriched in the biological process grouping, including catalytic activity, transport activity, energy metabolism pathway, steroid hormone, coenzyme, biological processes of vitamin A, D and metabolism of water-soluble vitamins, involving transcription, translation and energy metabolism related genes. The results of 143 SNPs showed statistically significant differences in ethnic distribution, and SNPs on chromosome 3 presented significant differences among ethnic groups. Principal component analysis 1 showed that rs1799852 on TF gene had 25%-50% explanatory validity, rs2118981 on RBP2 gene and rs1830084 on SRPRB gene had 50%-75% explanatory validity, rs1358024, rs1525892, rs1880669, rs3811647, rs3811658, rs6794945, rs7638018 and rs8177248 on TF gene had more than 75% explanatory validity.@*Conclusion@#SNPs associated with micronutrient deficiency risk of Chinese primary and middle school students are characterized with ethnic distributions.