Reinforcement of Rhodobacter sphaeroides cofactor NADPH to increase the production of farnesol / 生物工程学报

Farnesol (FOH) is produced by dephosphorylation of farnesyl diphosphate (FPP) derived from two universal building blocks, dimethylallyl diphosphate (DMAPP) and isopentenyl diphosphate (IPP). In Rhodobacter sphaeroides these building blocks are generated by MEP pathway, however, many of the biosynthetic reactions and biotransformations in the MEP pathway are limited by low availability of NADPH. Improvement of the amount of intracellular NADPH may enhance the synthesis of FOH. In this study, we utilized the strategies of increasing the production of NADPH and decreasing the consumption of NADPH. The expression of glucose 6-phosphate isomerase (pgi) and glutamate dehydrogenase (gdhA) were inhibited by RNA interference, respectively, and overexpression of 6-glucose phosphate dehydrogenase (zwf) and 6-glucose phosphate dehydrogenase (gnd) in the pentose phosphate pathway were carried out. The results showed that the content of NADPH in the recombinant strains increased significantly, the highest FOH production of RSpgii in the RNA interfered strain was 3.91 mg/g, and the FOH production increased to 3.43 mg/g after zwf gene and gnd gene has been overexpressed. In order to obtain strains with higher FOH production, we used RSpgii as the starting strain, and zwf, gnd and co-overexpressed zwf + gnd gene were overexpressed in RSpgii, respectively. The highest FOH production of the strain RSzgpi reached to 4.48 mg/g which was 2.24 times that of the starting strain RS-GY2.

Space Mutation Effects of Rhodobacter Sphaeroides / 航天医学与医学工程

Objective To study mutagenic effects of spaceflight on physiological and biochemical parameters of Rhodobacter sphaeroides and select high-yield mutants in co-enzyme Q10(CoQ10) production for providing the experimental and theoretical basis for industrial production through mutagenic effects of spaceflight.Methods Variations in stress resistance and CoQ10 production of isolated strains were studied,the strain Rhodobacter sphaeroides was taken back by a recoverable satellite after 15 d flight in space.Results Compared to the control,the strain was characterized by highter NaCl tolerance and higher stress resistance,as well as with broader scope in growth temperature and pH value after spaceflight.The mutant colonies appeared white or pink which was different from their original red.The CoQ10 production of mutant 10 strain was increased by 73.13% much higher than that of control.Conclusion Spaceflight mutagenic effects on Rhodobacter sphaeroides shows to be multi-factor compared to the traditional single-factor mutagenesis methods.It can enhance stress resistance and increase CoQ10 production of isolated strains,and can be utilized in industrial microbial mutagenesis and breeding in the future.