Metabolic engineering of Escherichia coli for production of hydroxytyrosol / 生物工程学报

Hydroxytyrosol is an important fine chemical and is widely used in food and medicine as a natural antioxidant. Production of hydroxytyrosol through synthetic biology is of important significance. Here we cloned and functionally characterized a hydroxylase encoding gene HpaBC from Escherichia coli BL21, and both subunits of this enzyme can be successfully expressed to convert the tyrosol into hydroxytyrosol. A HpaBC gene integration expression cassette under the tac promoter was constructed, and integrated into the genome of a tyrosol hyper-producing E. coli YMG5A*R using CRISPR-Cas9 technology. Meanwhile, the pathway for production of acetic acid was deleted, resulting in a recombinant strain YMGRD1H1. Shake flask fermentation showed that strain YMGRD1H1 can directly use glucose to produce hydroxytyrosol, reaching a titer of 1.81 g/L, and nearly no by-products were detected. A titer of 2.95 g/L was achieved in a fed-batch fermentation conducted in a 5 L fermenter, which is the highest titer for the de novo synthesis of hydroxytyrosol from glucose reported to date. Production of hydroxytyrosol by engineered E. coli lays a foundation for further construction of hydroxytyrosol cell factories with industrial application potential, adding another example for microbial manufacturing of aromatic compounds.

Clinical significance of S-100B protein in children with different degrees of amniotic fluid meconium contamination / 中国生化药物杂志

Objective Detection of S-100B protein in different degree meconium pollution level in serum of children with value.MethodsIn 2012 June to 2013 December in our department were simple meconium stained amniotic fluid in term newborns in 73 cases, and set up for the observation group, and according to the amniotic fluid pollution degree is divided into 47 cases of amniotic fluid of Ⅰ-Ⅱdegree pollution group and 26 cases in grade Ⅲmeconium group during the same period, selected 20 cases without amniotic fluid contamination in term healthy newborns for the control group, the groups were compared in S-100B protein content difference.ResultsⅢmeconium stained amniotic fluid were within 6h serum S-100B was significantly higher than that in control group(P0.05).Ⅲ meconium stained amniotic fluid in children with 72h also increased.ConclusionThird degree meconium stained amniotic fluid but normal Apgar score of newborns may still exist in clinical brain injury, so pay close attention to.