Systematic engineering of the rate-limiting step of b-alanine biosynthesis in Escherichia coli

BACKGROUND: Large amounts of b-alanine are required in fine chemical and pharmaceutical synthesis and other fields. Profitable and green methods are required for the industrial production of b-alanine. RESULTS: Replacing endogenous panD of Escherichia coli with heterologous CgpanD from Corynebacterium glutamicum enabled b-alanine synthesis of 0.67 g/L by strain B0016-082BB. Overexpressing CgpanD on both plasmids and chromosomes to enhance the rate-limiting step improved the b-alanine titer to 4.25 g/L in strain B0016-083BB/pPL451-panD with a slighter metabolic burden. Growth factors were introduced by addition of yeast extract, and 6.65 g/L of b-alanine was synthesized by strain B0016- 083BB/pPL451-panD in the M9-3Y medium. CONCLUSIONS: Enhancement of the rate-limiting steps in the b-alanine biosynthetic pathway, recruitment of the temperature-sensitive inducible pL promoter, and optimization of the fermentation process could efficiently increase b-alanine production in E. coli.

The Effects of Taurine and ??-alanine on Blood Glucose and Blood Lipid Concentrations in Insulin-treated Diabetic Rats / 대한지역사회영양학회지

The purpose of this study was to determine the effects oftaurine supplementation and taurine depletion on blood glucose and blood lipid concentrations in insulin-treated diabetic rats. Four groups of Sprague-Dawley male rats were fed the purified diet for 3 weeks ; nontaurine-supplemented diabetic rats(E0), nontaurine-supplemented diabetic rats with insulin treatment(E0+I), 1% taurine-supplemented diabetic rats with insulin treatment(E1+I) and taurine-depleted diabetic rats with insulin treatment(EA+I). Diabetes was induced by streptozotocin injection(50mg/kg B.W.). Isophane insulin was given subcutaneously into the abdominal wall of the diabetic rats(4 unit/rat/day). E1+I were supplemented with 1% taurine in drinking water. To induce taurine depletion, EA+I were treated with 5% beta-alanine in drinking water. E1+I had significantly higher body weight compared to that fo E0. The food intakes of E1+I and E0+I were significantly decreased compared to that of E0. There was no sigfniciant difference in food intake between E1+I and E0+I. The water intake of rats was significantly different among the groups ; E0>E0+I>E1+I>EA+I. The urine volume of E0 was significantly increased compared to those of insulin-treated goups. The blood glucose concentration of E0 was significantly increased compared to those of insulin-treated groups. In the oral glucose tolerance test(OGTT), E0+I and E1+I had significantly lower blood blucose concentrations compared to E0 after 30 min. Also EA+I had significantly lower bloodglucose concentrtion compared to E0 and E0+I. The plasma total cholesterol and LDL-cholesterol concentratons of EA+I were significantly incrased compared to those of other groups. Therefore, it may be suggested that tuarine supplementation is useful for insulin-dependent diabetes in order to prevent diabetic complications suchas cardiac vascular diseases.