Engineering Saccharomyces cerevisiae for efficient production of glucaric acid / 生物工程学报

As an important dicarboxylic acids existing in nature, glucaric acid has been widely used in medical, health, and polymer materials industry, therefore it is considered as one of the "top value-added chemicals from biomass". In this study, using Saccharomyces cerevisiae as a chassis microorganism, the effects of overexpression of myo-inositol transporter Itr1, fusional expression of inositol oxygenase MIOX4 and uronate dehydrogenase Udh, and down-expression of glucose-6-phosphate dehydrogenase gene ZWF1 on the glucaric acid production were investigated. The results showed that the yield of glucaric acid was increased by 26% compared with the original strain Bga-3 under shake flask fermentation after overexpressing myo-inositol transporter Itr1. The yield of glucaric acid was increased by 40% compared with Bga-3 strain by expressing the MIOX4-Udh fusion protein. On these basis, the production of glucaric acid reached 5.5 g/L, which was 60% higher than that of Bga-3 strain. In a 5 L fermenter, the highest yield of glucaric acid was 10.85 g/L, which was increased 80% compared with that of Bga-3 strain. The application of the above metabolic engineering strategy improved the pathway efficiency and the yield of glucaric acid, which may serve as a reference for engineering S. cerevisiae to produce other chemicals.

Construction of a glucaric acid biosensor for screening myo-inositol oxygenase variants / 生物工程学报

Glucaric acid (GA), a top value-added chemical from biomass, has been widely used for prevention and control of diseases and the production of polymer materials. In GA biosynthesis pathway, the conversion of inositol to glucuronic acid that catalyzed by myo-inositol oxygenase is the limiting step. It is necessary to improve MIOX activity. In the present study, we constructed a high-throughput screening system through combing the concentration of GA with the green fluorescent protein fluorescence intensity. By applying this screening system, three positive variants (K59V/R60A, R171S and D276A) screened from the mutant library. In comparison, the recombinant strain Escherichia coli BL21(DE3)/MU-R171S accumulated more GA, 136.5% of that of the parent strain.

Evaluation of the effect of retrograde intrarenal surgery with myo-inositol oxygenase

Objective: To investigate the effect of retrograde intra-renal surgery [RIRS] on kidneys using the myoinositol oxygenase [MIOX] enzyme. MIOX is a renal tubular-specific novel marker for the early diagnosis of acute kidney injury

Methods: A total of twenty seven individuals that had undergone RIRS to treat kidney stones were included in the study. Biochemical tests were performed on serum samples collected immediately before RIRS [hour 0] and at the 6th and 24th hours after the surgery

Results: The creatinine value at hour 6 was lower than the baseline [hour 0] value [p = 0.0305]. Cystatin C at hour 6 was lower than the value measured at hour 24 [p = 0.0142]. Similarly, MIOX was lower at hour 6 compared to hour 24 [p = 0.0214]. MIOX/creatinine at hour 6 was lower than the value calculated at hour 24 [p = 0.0348]. The basal values of MIOX and creatinine were found to have a positive correlation [correlation coefficient r = 0.5946, p = 0.0035]

Conclusions: Similar to the serum creatinine, the serum MIOX level provides information about kidney functions. RIRS was confirmed to be a safe procedure for the treatment of acute kidney injury with no negative effects on the kidneys