Isolation of high osmotic-tolerant mutants of Escherichia coli for succinic acid production by metabolic evolution / 生物工程学报

Succinic acid production was inhibited by high osmotic pressure caused by the accumulation of sodium ions in the process of two-stage fermentation by Escherichia coli using Na2CO3 as the pH regulator. To enhance the resistance of this strain to osmotic stress, the possibility to isolate high NaCl-tolerant mutant strain of Escherichia coli for succinic acid production by metabolic evolution was investigated. The metabolic evolution system was used as a mutant-generating system, allowing the cells to be continuously cultured at the maximum specific growth rate. The mutant strain can grow at maximum rate in the condition of high osmotic by gradually improving the concentration of NaCl in a continuous culture. Then the high osmotic-tolerant mutant strain of E. coli XB4 was selected with NaCl as the osmo-regulator. When using Na2CO3 as the pH regulator, E. coli XB4 was used in a 7.0 L fermenter during two-stage fermentation. After 60 h anaerobic fermentation, the mutant strain XB4 produced 69.5 g/L succinic acid with a productivity of 1.18 g/(L x h), which were increased by 18.6% and 20% compared with that of the parent strain.

Mechanism of four regulating-intestines prescriptions in the treatment of ulcerative colitis / 中国组织工程研究

AIM: To analyze curative effect of four regulating-intestines prescriptions (Wumei Wan, Baitouweng Tang, Shenling Baizhu San and Tongxie Yao-fang) on the treatment of ulcerative colitis (UC) through summing up the previous animal experimental results.METHODS: We collected the conclusions in the papers related to four regulating-intestines prescriptions for the treatment of UC which were published recently, made comparisons from the aspectsof symptoms, physical sign, pathological change, cytokine and its protein expression, blood adhesion molecule, cell apoptosis and controlling gene and analyzed the pathogenesis of UC and action mechanism of four regulating-intestines prescriptions. Four regulating-intestines prescriptions included Wumei Wan,Baitouweng Tang, Shenling Baizhu San and Tongxie Yaofang. Wumei Wan is from Treatise on Exogenous Febrile Diseases and Synopsis of the Golden Chamber, which consists of dark plum, asarum herb, dried ginger, Chinese goldthread, Chinese angelica root, aconite root, pricklyash peel, cassia twig,ginseng (sun-dried ginseng) and bark of cork tree and has marked effect in treating colic caused by ascariasis and persistent dysentery. Baitouweng Tang, from Treatise on Exogenous Febrile Diseases, consists of medicinal herbs such as pulsatilla root, Chinese goldthread, bark of cork tree and ash bark, which has functions of clearing away the heat-evil, expelling superficial evils and relieving dysentery. In addition, it has marked effect in treating heat-type dysentery. Shenling Baizhu San, from Prescriptions of Peaceful benevolent Dispensary, consists of medicinal herbs such as pulp of lotus seed, coix seed, amomum fruit, balloon flower root, white hyacinth bean, poria, ginseng (sun-dried ginseng), glycyrrhiza, bighead atractylodes and rhizoma dioscoreae, which has the nature of replenishing qi to invigorate the spleen and eliminate wetness to arrest diarrhea and has marked effect on treating diarrhea due to the hypofunction of spleen. Tongxie Yao-fang which is from The Complete Works of Zhang Jingyue consists of four herbals of agehead atractylodes, root of herbaceous peony, dried tangerine peel and ledebouriella root and has the functions of soothing liver and invigorating spleen and stopping diarrhea, and has marked effect on treating liver sthenia and deficient spleen, borborygmus and abdominal pain and diarrhea.RFSULTS: ① Because UC is a chronic protracted dysentery with deficiency of vital energy and existing of evil energy, the vital energy will be harmed if its treatment is specialized in removing and dissolving the stagnation, evil energy will continue to exist and stagnation will continue to accumulate if its treatment is specialized in strengthening vital energy and inducing astringency. Only supporting healthy energy and expelling evil energy is the correct therapy method. This is in accordance with the main treatment of Wumei Wan ②Eliminating dampness and pathogenic heat from the blood to treat diarrhea is the main treatment method of Baitouweng Tang, and this is incompletely suitable for the treatment of UC.③Shenling Baizhu San had the effect on soothing liver and invigorating spleen and stopping diarrhea, and this is also incompletely suitable for the treatment of UC. ④ The prescription of Tongxie Yaofang is used for treating diarrhea caused by deficient spleen and liver sthenia, and spleen controlled by liver, and abnormal ascent and descent. It accords with main pathogenesis of UC, deficient spleen, excessive dampness of deficient spleen and it is weaker in invigorating the spleen in catabasis of UC than Shenling Baizhu San. Therefore, Wumei Wan has the best curative effect,Baitouweng Tang the second, Shengling Baizhu San the third and Tongxie Yaofang a little poor.CONCLUSION: UC belongs to recurrent dysentery, and its pathogenesis is in accordance with the main treatment of Wumei Wan, but not the other three prescriptions, so Wumei Wan is the most efficient prescription in treating ulcerative colitis. Diagnosis and treatment based on an overall analysis of signs and symptoms of TCM is the premise of obtaining the best curative effect. Modeling of animal tests must be consistent with the type of syndrome of the traditional Chinese medicine. Ating ulcerative colitis (UC) from aspects such as symptom, physical sign, pathological changes, adherence factor, cytokine and its protein expression, apoptosis and its controlling gene by means of modeling, which proves their functions and effects are different and their curative effect are also different due to their different ingredient though they all have the functions of treating. Results of this test show Wumei Wan has the best curative effect, Baitouweng Tang the second, Shenling Baizhu San the third and Tongxie Yaofang a little poor[1-11] Mechanism of four regulating-intestines prescription in the treatment of ulcerative colitis is discussed from the viewpoints of traditional Chinese medicine as follows.