Production of fatty acids by engineered Ogataea polymorpha / 生物工程学报

Fatty acids (FA) are widely used as feed stocks for the production of cosmetics, personal hygiene products, lubricants and biofuels. Ogataea polymorpha is considered as an ideal chassis for bio-manufacturing, due to its outstanding characteristics such as methylotroph, thermal-tolerance and wide substrate spectrum. In this study, we harnessed O. polymorpha for overproduction of fatty acids by engineering its fatty acid metabolism and optimizing the fermentation process. The engineered strain produced 1.86 g/L FAs under the optimized shake-flask conditions (37℃, pH 6.4, a C/N ratio of 120 and an OD600 of seed culture of 6-8). The fed-batch fermentation process was further optimized by using a dissolved oxygen (DO) control strategy. The C/N ratio of initial medium was 17.5, and the glucose medium with a C/N ratio of 120 was fed when the DO was higher than 30%. This operation resulted in a titer of 18.0 g/L FA, indicating the potential of using O. polymorpha as an efficient cell factory for the production of FA.

Advances in metabolic engineering of methylotrophic yeasts / 生物工程学报

Methylotrophic yeasts are considered as promising cell factories for bio-manufacturing due to their several advantages such as tolerance to low pH and high temperature. In particular, their methanol utilization ability may help to establish a methanol biotransformation process, which will expand the substrate resource for bio-refinery and the product portfolio from methanol. This review summarize current progress on engineering methylotrophic yeasts for production of proteins and chemicals, and compare the strengths and weaknesses with the model yeast Saccharomyces cerevisiae. The challenges and possible solutions in metabolic engineering of methylotrophic yeasts are also discussed. With the developing efficient genetic tools and systems biology, the methylotrophic yeasts should play more important roles in future green bio-manufacturing.

Ficolin-A enhances inhibition of the C-terminal 19 kDa region ofmerozoite surface protein-1 of plasmodium berghei using test in vivo

Malaria remains a serious public health problem with significant morbidity and mortality. This study was conducted to identify whether ficolin-A could play an active role of against malaria infection. The function of ficolin-A was analyzed in mouse model. The open reading frame of ficolin-A was cloned from the liver of new born C57BL/6 mice by RT-PCR and then inserted into the expression vector of eukaryon to construct p VAX1-ficolin-A plasmid. Meanwhile, the open reading frame of the 19-kDa fragment of merozoite surface protein-1 of Plasmodium berghei [MSP1[19]] was cloned and then the expression vector of eukaryon, p VAX1- MSP1[19] was constructed. Both recombinant vectors were used in the mouse model of infection by Plasmodium berghei. p VAX 1-ficolin-A alone could not significantly suppress parasite density and prolong survival time of infection mice; however, when injected p VAX1-ficolin-A and p VAX1- MSP1[19] together, the percent of invasion by Plasmodium was decreased [from 43.78% to 22.23% at 10 day after infection, compared to vector] and the survival time was prolonged significantly in the infection mouse model [P=0.01]. Ficolin-A can enhance the immunoprotection of MSP1[19], it implies ficolin-A may be used as immunoenhancer in the study of vaccine defending malaria

Advanced biofuel-oriented engineering of fatty acid pathway: a review / 生物工程学报

Biofuel is in high demand as an alternative energy source for petroleum and diesel. Fatty acid-based biofuel has higher energy density and better compatibility with existing infrastructures. Microbial fatty acid biosynthetic pathway is important to develop biofuel. In this article, recent progresses on the modification and reconstruction of fatty acid metabolism for the production of biofuel were reviewed, with a focus on micro-diesel, long chain fatty alcohol and alkane. Problems, solutions and directions for further development of fatty acid-based biofuel were also discussed in the respect of synthetic biology.

Potentials of phototrophic bacteria in treating pharmaceutical wastewater

A suspended growth photobioreactor was utilized to treat pharmaceutical wastewater by a wild strain purple non-sulfur photosynthetic bacterium isolated from the soil. The strain was named Z08 and identified as Rhodobacter-sphaeroides by 16SrDN. The photobioreactor was illuminated externally with two [40 W] fluorescent compact light sources on both sides. Its operation pH and temperature were between 6.8 - 7.0 and 20 - 30°C, respectively. Optimum growth of the isolate was obtained after enrichment of the pharmaceutical wastewater with 0.5% ammonium sulfate and 0.1% yeast extract under microaerobic optimum light [6000 1x] condition at 5d retention. Using these optimum conditions, the maximum dry cell weight and chemical oxygen demand percentage removal were 880 mg/L and 80%. Chemical analysis of the culture after treatment of the enriched and non-enriched wastewater showed the crude protein content of the biomass to be 54.6% and 38.0%, respectively. This study proved that photosynthetic bacteria could transform complex wastewater that contains recalcitrant organic compounds with a resultant recovery of useful products