Construction of a recombinant Escherichia coli for high trehalose production / 生物工程学报

Trehalose, a compatible solute, is widely used in food, cosmetics, pharmaceutical products and organ transplantation. Nowadays, trehalose is mostly produced by enzymatic synthesis with many secondary products and lowpurity. In this study, high amount of trehalose was produced by recombinant E. ccli fermentation. First, a bifunctional trehalose gene TPSP was amplified from genome of C. hutchinscoii. Second, an expression vector pTac-HisA containing TPSP was constructed and transformed into the host E. coli. Expression of this bifunctional enzyme-TPSP converted glucose to trehalose. The result suggested that TPSP from C. hutchinsonji has been successfully expressed in E. ccoi. High amount of extracellular trehalose generated from glucose by whole-cell catalysis and After optimization, the production of trehalose in shake flasks was improved to 1.2 g/L and the relative conversion rate reached 21%. The production in bioreactor reached 13.3 g/L and the relative conversion rate reached 48.6%. It is the first time to realize the functional expression of the bifunctional enzyme-TPSP of C. hutchinsonii in E. coli and achieved the conversion form glucose to trehalose. This study laid a foundation for industrial large-scale production of trehalose.

Efficacies of fluid resuscitation plus continuous veno-venous hemofiltration in the treatment of septic shock / 中华全科医师杂志

A total of 58 patients with simple septic shock were recruited from intensive care unit and divided into control group (n =28) and treatment group (n =30) according to treatment modalities.The control group was routinely treated.The treatment group received continuous veno-venous hemofiltration (CVVH) for 10-14 days plus routine measures.After 3 days,the score of acute physiology and chronic health evaluation-Ⅱ (APACHE-Ⅱ) of the treatment group was better than that of the control group (P ＜ 0.01).And sequential organ failure assessment (SOFA),left ventricular end diastolic diameter (LVEDD),left ventricular end systolic diameter (LVEDS) and left ventricular ejection fraction (LVEF) improved significantly (P ＜ 0.05).And the relevant blood biochemical parameters improved significantly better than the control group (P ＜ 0.05).In the group CVVH,there were mortality (n =7,23％) and multiple organ failure (MODS) (n =6,20％) ; In the control group,mortality (n =14,50％) and MODS (n =13,46％).The mortality rate had inter-group differences of statistical significance (x2 =4.38,P ＜0.05).Thus early volume resuscitation plus CVVH had excellent curative efficacies for septic shock.

Flexible interwoven termini determine the thermal stability of thermosomes

Group II chaperonins, which assemble as double-ring complexes, assist in the refolding of nascent peptides or denatured proteins in an ATP-dependent manner. The molecular mechanism of group II chaperonin assembly and thermal stability is yet to be elucidated. Here, we selected the group II chaperonins (cpn-α and cpn-β), also called thermosomes, from Acidianus tengchongensis and investigated their assembly and thermal stability. We found that the binding of ATP or its analogs contributed to the successful assembly of thermosomes and enhanced their thermal stabilities. Cpn-β is more thermally stable than cpn-α, while the thermal stability of the hetero thermosome cpn-αβ is intermediate. Cryo-electron microscopy reconstructions of cpn-α and cpn-β revealed the interwoven densities of their non-conserved flexible N/C-termini around the equatorial planes. The deletion or swapping of their termini and pH-dependent thermal stability assays revealed the key role of the termini electrostatic interactions in the assembly and thermal stability of the thermosomes.