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
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.