A total of 126 bacterial strains were isolated from soil samples. Among them, 11 isolates were found positive for amylase production. Strain YL produced the largest zone of clearance on plate assay. The isolate YL was...A total of 126 bacterial strains were isolated from soil samples. Among them, 11 isolates were found positive for amylase production. Strain YL produced the largest zone of clearance on plate assay. The isolate YL was identified as Bacillus sp. based on morphological and physiochemical characterization. According to 16S rRNA gene sequencing data, the closest phylogenetic neighbor of strain YL was Bacillus amyloliquefaciens （99.54%）. After that, an optimization of culture conditions was carried out for the improvement of a-amylase production. Response surface methodology （RSM） was applied to evaluate the effect of medium components including wheat bran, cottonseed extract, yeast extract, starch, NaC1 and CaCl2. Three variables （wheat bran, cottonseed extract, and starch）, which were identified to significantly affect amylase production by Plackett-Burman design were further optimized using response surface methodology of Box-Behnken design （BBD）. The optimal concentrations estimated for each variable related to the maximum of amylase activity （86 kU/mL） were 10.80 g/L wheat bran, 9.90 g/L cottonseed extract, 0.5 g/L starch, 2.0 g/L yeast extract, 5.00 g/L NaCl and 2.00 g/L CaC12. The fermentation using optimized culture medium allowed a significant increase in amylase production （by 3-fold）. The improvement in the a-amylase production after optimization process can be considered adequate for large-scale applications.展开更多
Disulfide bond formation protein A （DsbA） is one of the important helper proteins for folding in protein synthesis in vivo. In this study, purification of recombinant DsbA was investigated by examining four importan...Disulfide bond formation protein A （DsbA） is one of the important helper proteins for folding in protein synthesis in vivo. In this study, purification of recombinant DsbA was investigated by examining four important factors with Box-Behnken design method, a statistic-based design of experiments. The optimal operation conditions were obtained by adopting the effectiveness coefficient method on the multi-objective problem, which takes the protein recovery, purification efficiency and throughput of ion-exchange chromatography into account. After the optimization, protein recovery of 96.8% and purity higher than 95% DsbA was achieved, and the productivity was （377.9±1.7） mg soluble DsbA per liter broth. The purified protein was identified by peptide mass fingerprinting matching the record of gil2624856, a mutant of DsbA. The DsbA was preliminarily applied to the refolding of denatured lysozyme in vitro.展开更多
The production of cellulase in Bacillus amyloliquefaciens UNPDV-22 was optimized using response surface methodology （RSM）. Central composite design （CCD） was used to study the interactive effect of culture conditi...The production of cellulase in Bacillus amyloliquefaciens UNPDV-22 was optimized using response surface methodology （RSM）. Central composite design （CCD） was used to study the interactive effect of culture conditions （temperature, pH, and inoculum） on cellulase activity. Results suggested that temperature and pH all have significant impact on cellulase production. The use of RSM resulted in a 96% increase in the cellulase activity over the control of non-optimized basal medium. Optimum cellulase production of 13 U/mL was obtained at a temperature of 42.24 ℃, pH of 5.25, and inoculum size of 4.95% （v/v） in a fermentation medium containing wheat bran, soybean meal and malt dextrin as major nutritional factors.展开更多
In addition to regulating acid secretion, the gastric antral hormone gastrin regulates several important cellular processes in the gastric epithelium including proliferation, apoptosis, migration, invasion, tissue rem...In addition to regulating acid secretion, the gastric antral hormone gastrin regulates several important cellular processes in the gastric epithelium including proliferation, apoptosis, migration, invasion, tissue remodelling and angiogenesis. Elevated serum concentrations of this hormone are caused by many conditions, particularly hypochlorhydria (as a result of autoimmune or Helicobacter pylori (H pylori)-induced chronic atrophic gastritis or acid suppressing drugs) and gastrin producing tumors (gastrinomas). There is now accumulating evidence that altered local and plasma concentrations of gastrin may play a role during the development of various gastric tumors. In the absence of H pylori infection, marked hypergastrinemia frequently results in the development of gastric enterochromaffi n cell-like neuroendocrine tumors and surgery to remove the cause of hypergastrinemia may lead to tumor resolution in this condition. In animal models such as transgenic INS-GAS mice, hypergastrinemia has also been shown to act as a cofactor with Helicobacter infection during gastric adenocarcinoma development. However, it is currently unclear as to what extent gastrin also modulates human gastric adenocarcinoma development. Therapeutic approaches targeting hypergastrinemia,such as immunization with G17DT, have been evaluated for the treatment of gastric adenocarcinoma, with some promising results. Although the mild hypergastrinemia associated with proton pump inhibitor drug use has been shown to cause ECL-cell hyperplasia and to increase H pylori-induced gastric atrophy, there is currently no convincing evidence that this class of agents contributes towards the development of gastric neuroendocrine tumors or gastric adenocarcinomas in human subjects.展开更多
基金Project(31000350) supported by the National Natural Science Foundation of ChinaProject(2010CB630902) supported by the National Basic Research Program of China
文摘A total of 126 bacterial strains were isolated from soil samples. Among them, 11 isolates were found positive for amylase production. Strain YL produced the largest zone of clearance on plate assay. The isolate YL was identified as Bacillus sp. based on morphological and physiochemical characterization. According to 16S rRNA gene sequencing data, the closest phylogenetic neighbor of strain YL was Bacillus amyloliquefaciens （99.54%）. After that, an optimization of culture conditions was carried out for the improvement of a-amylase production. Response surface methodology （RSM） was applied to evaluate the effect of medium components including wheat bran, cottonseed extract, yeast extract, starch, NaC1 and CaCl2. Three variables （wheat bran, cottonseed extract, and starch）, which were identified to significantly affect amylase production by Plackett-Burman design were further optimized using response surface methodology of Box-Behnken design （BBD）. The optimal concentrations estimated for each variable related to the maximum of amylase activity （86 kU/mL） were 10.80 g/L wheat bran, 9.90 g/L cottonseed extract, 0.5 g/L starch, 2.0 g/L yeast extract, 5.00 g/L NaCl and 2.00 g/L CaC12. The fermentation using optimized culture medium allowed a significant increase in amylase production （by 3-fold）. The improvement in the a-amylase production after optimization process can be considered adequate for large-scale applications.
基金Supported by the National Natural Science Foundation of China （21036005）.
文摘Disulfide bond formation protein A （DsbA） is one of the important helper proteins for folding in protein synthesis in vivo. In this study, purification of recombinant DsbA was investigated by examining four important factors with Box-Behnken design method, a statistic-based design of experiments. The optimal operation conditions were obtained by adopting the effectiveness coefficient method on the multi-objective problem, which takes the protein recovery, purification efficiency and throughput of ion-exchange chromatography into account. After the optimization, protein recovery of 96.8% and purity higher than 95% DsbA was achieved, and the productivity was （377.9±1.7） mg soluble DsbA per liter broth. The purified protein was identified by peptide mass fingerprinting matching the record of gil2624856, a mutant of DsbA. The DsbA was preliminarily applied to the refolding of denatured lysozyme in vitro.
文摘The production of cellulase in Bacillus amyloliquefaciens UNPDV-22 was optimized using response surface methodology （RSM）. Central composite design （CCD） was used to study the interactive effect of culture conditions （temperature, pH, and inoculum） on cellulase activity. Results suggested that temperature and pH all have significant impact on cellulase production. The use of RSM resulted in a 96% increase in the cellulase activity over the control of non-optimized basal medium. Optimum cellulase production of 13 U/mL was obtained at a temperature of 42.24 ℃, pH of 5.25, and inoculum size of 4.95% （v/v） in a fermentation medium containing wheat bran, soybean meal and malt dextrin as major nutritional factors.
基金Supported by Wellcome Trust Clinical Research Training Fellowship to MDB
文摘In addition to regulating acid secretion, the gastric antral hormone gastrin regulates several important cellular processes in the gastric epithelium including proliferation, apoptosis, migration, invasion, tissue remodelling and angiogenesis. Elevated serum concentrations of this hormone are caused by many conditions, particularly hypochlorhydria (as a result of autoimmune or Helicobacter pylori (H pylori)-induced chronic atrophic gastritis or acid suppressing drugs) and gastrin producing tumors (gastrinomas). There is now accumulating evidence that altered local and plasma concentrations of gastrin may play a role during the development of various gastric tumors. In the absence of H pylori infection, marked hypergastrinemia frequently results in the development of gastric enterochromaffi n cell-like neuroendocrine tumors and surgery to remove the cause of hypergastrinemia may lead to tumor resolution in this condition. In animal models such as transgenic INS-GAS mice, hypergastrinemia has also been shown to act as a cofactor with Helicobacter infection during gastric adenocarcinoma development. However, it is currently unclear as to what extent gastrin also modulates human gastric adenocarcinoma development. Therapeutic approaches targeting hypergastrinemia,such as immunization with G17DT, have been evaluated for the treatment of gastric adenocarcinoma, with some promising results. Although the mild hypergastrinemia associated with proton pump inhibitor drug use has been shown to cause ECL-cell hyperplasia and to increase H pylori-induced gastric atrophy, there is currently no convincing evidence that this class of agents contributes towards the development of gastric neuroendocrine tumors or gastric adenocarcinomas in human subjects.
