RESUMEN
Poly ?-glutamate is a biopolymer material that has a good application prospect.The Vitreoscilla hemoglobin(VHb) gene was integrated into the chromosome of Bacillus licheniformis WX-02 by integrative vector pDG1730-vgb.The expression of VHb was confirmed by CO-difference spectra analysis.It was shown by the results of batch cultures in a 3 L bioreactor that biomass and ?-PGA obtained in the recombinant M2 were 25.5 % and 20% higher than those of the control respectively.
RESUMEN
Bacillus subtilis B6-1 was used as an original strain for mutagenic treatment and a defined medium was used as the selective medium. A mutant named B. subtilis W003 was isolated after three serial ultraviolet (UV) irradiations and one diethyl sulfate (DES) treatment. The ?-PGA yield on a rotary shaker was enhanced from 10.9 g/L in parental strain to 20.5 g/L in the mutant. It was illustrated by single factor experiments that the optimal carbon and nitrogen sources were glucose and (NH4)2SO4 respectively. The optimal fermentation medium was achieved by orthogonal test. In the optimal medium, a ?-PGA yield of 45.3 g/L was obtained after 36 h cultivation.
RESUMEN
Zwittermicin A was purified by ion exchange resin and HPLC from supernatants of Bacillus thuringiensis.subsp.kurstaki strain D1-23 cultivation.2.89mg pure Zwittermicin A was acquired,proved by HPLC-MS.Results show that the optimized wash concentration of NH_ 4 H_ 2 PO_ 4 is 5mmol/L at first step.Next step CH_ 3 COONH_ 4 concentration is 30 mmol/L,the gradient pH is 8.0～9.5.Totally 93% Zwittermicin A can be reserved with ion exchange resin.The temperature and pH stability experiments show the half life of Zwittermicin A is 48.22 minutes in 100℃,and it is more stable in lower pH in pH 2.0～12.0.