Effects of deleting peptidoglycan hydrolase genes on the viable cell counts of Bacillus amyloliquefaciens and the yield of alkaline protease / 生物工程学报

In order to explore the effect of peptidoglycan hydrolase on the viable cell counts of Bacillus amyloliquefaciens and the yield of alkaline protease, five peptidoglycan hydrolase genes (lytC, lytD, lytE, lytF and lytG) of B. amyloliquefaciens TCCC111018 were knocked out individually. The viable cell counts of the bacteria and their alkaline protease activities before and after gene deletion were determined. The viable cell counts of the knockout mutants BA ΔlytC and BA ΔlytE achieved 1.67×106 CFU/mL and 1.44×106 CFU/mL respectively after cultivation for 60 h, which were 32.5% and 14.3% higher than that of the control strain BA Δupp. Their alkaline protease activities reached 20 264 U/mL and 17 265 U/mL, respectively, which were 43.1% and 27.3% higher than that of the control strain. The results showed that deleting some of the peptidoglycan hydrolase genes effectively maintained the viable cell counts of bacteria and increased the activity of extracellular enzymes, which may provide a new idea for optimization of the microbial host for production of industrial enzymes.

Microdialysis recovery of cefradine in vitro / 药学实践杂志

Objective To determine the in vitro recovery rate and influencing factors of cefradine microdialysis. Methods Two different methods (loss method, gain method) of microdialysis concentration and LC-MS/MS were used to determine the in vitro recovery rate of cefradine. The effect of flow rate and concentration of the perfusate on the recovery rate were investigated. To explore the feasibility of microdialysis technology for pharmacokinetic studies in cefradine. Results The LC-MS/MS analysis method was linear in the required range and the method was sensitive and reliable. There was no significant difference in the recovery rate measured by gain or loss method. Under the same conditions, the in vitro recovery of the probe decreased with increasing flow rate, independent of the drug concentration around the probe. Conclusion Microdialysis technique could be used to study the pharmacokinetics of cefradine, and loss method could be used to determine the in vivo recovery rate and pharmacokinetics of cefradine on microdialysis.