Construction of Saccharomyces cerevisiae whole-cell biocatalyst system for conversion miltiradiene / 药学学报

Tanshinones are the bioactive components of the Chinese medicinal herb Salvia miltiorrhiza, while its biosynthetic pathway remains to be characterized. Rapid identification and characterization of the genes correlated to tanshinones biosynthesis is very important. As one of the intermediates of tanshinones biosynthesis, the ferruginol content is relative low in both root and engineered bacteria. It is urgent to construct an efficient system for conversion of miltiradiene to ferruginol to obtain large amount of ferruginol as the substrates for further identifying other downstream genes involved in tanshinones biosynthesis. In this study, we constructed the whole-cell yeast biocatalysts co-expressing miltiradiene oxidase CYP76AH1 and cytochrome P450 reductases (SmCPR1) from Salvia miltiorrhiza, and then characterized it with RT-PCR. After permeabilization, the yeast whole-cell could catalyze turnover of miltiradiene to ferruginol efficiently through single-step biotransformation with a conversion efficiency up to 69.9%. The yeast whole-cell biocatalyst described here not only provide an efficient platform for producing ferruginol in recombinant yeast but also an alternative strategy for identifying other CYP genes involved in tanshinones biosynthesis.

Microcalorimetric investigation of two cephalosporins on colon bacteria activity / 药学学报

The effects of cephradinum and ceftazidime on the metabolism of Escherichia coli (E. coli) DH5alpha was determined by microcalorimetry. The microbial activity was recorded as power-time curves through an ampoule method with a TAM Air Isothermal Microcalorimeter at 37 degrees C. The parameters such as the growth rate constant (k), inhibitory ratio (I), the maximum power output (Pm) and the time (tm) corresponding to the maximum power output were calculated. The results show that the ceftazidime has a better inhibitory effect on E. coli DH5alpha than cephradinum.

Optimized culture medium and fermentation conditions for lipid production by Rhodosporidium toruloides / 生物工程学报

Culture medium and fermentation conditions for lipid production by Rhodosporidium toruloides were optimized with single factor and uniform design experiment. The best medium recipe was found with 70 g/L glucose, 0.1 g/L (NH4)2SO4, 0.75 g/L yeast extract, 1.5 g/L MgSO4. 7H2O, 0.4g/L KH2PO4, sterilized at 121 degrees C for 15 min, and then supplemented with ZnSO4 1.91 x 10(-6) mmol/L, CaCl2 1.50 mmol/L, MnCl2 1.22 x 10(-4) mmol/L and CuSO4 1.00 x 10(-4) mmol/L. The optimal fermentation conditions were as follows: 50 mL of medium (pH 6.0) in 250 mL Erlenmeyer flask with 10% inoculum (28h) under orbital shaking at 200 r/min for 120h at 30 degrees C. Under these conditions, yeast biomass accumulated lipids up to 76.1%.

Lipid Production by Rhodosporidium toruloides Using Jerusalem Artichoke Tubers / 中国生物工程杂志

The effects of pretreatment methods of Jerusalem artichoke tubers on microbial lipids fermentation with an oleaginous yeast strain Rhodosporidium toruloides Y4 were investigated in shaking flask culture.The yeast strain accumulated substantial amount of lipids using either purple-or white-skinned Jerusalem artichoke tubers as sole carbon and energy source.When cells were cultured on the extracted juice or the acidhydrolysate,cellular lipid content reached 40%(w/w),while cultured on the pulp,the white-skinned tubershadhigher lipid productivity,yielding 12.1 g lipids per100 g dried tubers.Major fatty acid constituents of microbial lipids were those contained 16-and 18-carbon atoms based on GC analysis,which is quite similar to traditional vegetable oil.Microbial lipids prepared from Jerusalem artichoke can be applied to biodiesel production.