Project description:Over the past three decades, due to the universal application of Pichia yeast in the fermentation industry as well as the establishment of Pichia pastoris fermentation process for more than 30 years, the technology of the whole process has become very mature and has now reached a stagnated period of growth. However, studies and research conducted on the genomics of the classic fermentation process and the uncovering of the biological phenomena in the fermentation process from the point of view of high-throughput gene or protein is still in its early stages, and there is still insufficient data within this field. First, in collaboration with Agilent Company, we designed and prepared an expression microarray that could be used for the detection of Pichia pastoris transcriptomics. The transcriptomic changes in the five key technology steps (time points), during the fermentation process of Pichia pastoris would then be detected with the aid of an expression microarray. The five key steps of technology described above formed two important biological processes, namely, the limiting carbon source replacement and secondly, the fermentative production of exogenous proteins. The biological phenomena involved in these two processes were displayed and analyzed at the transcriptional level. In addition to this, with regard to the most important function in the fermentation process of Pichia pastoris, oxid-reduction, the metabolic drift process was analyzed and the important genes that might dominate the changes in the metabolic flux were discovered creatively by using the function tree method in this paper. This study was undertaken from the point of view of the transcriptome and the biological phenomena in the fermemntation process of Pichia pastoris. Both of which, were thoroughly explained during this study. The hope is for many more researchers to optimize the strain fermentation process, to produce proteins at the genetic level, as well as providing and obtaining new perspectives and detailed scientific data for the continued development within this field.

Project description:Over the past three decades, due to the universal application of Pichia yeast in the fermentation industry as well as the establishment of Pichia pastoris fermentation process for more than 30 years, the technology of the whole process has become very mature and has now reached a stagnated period of growth. However, studies and research conducted on the genomics of the classic fermentation process and the uncovering of the biological phenomena in the fermentation process from the point of view of high-throughput gene or protein is still in its early stages, and there is still insufficient data within this field. First, in collaboration with Agilent Company, we designed and prepared an expression microarray that could be used for the detection of Pichia pastoris transcriptomics. The transcriptomic changes in the five key technology steps (time points), during the fermentation process of Pichia pastoris would then be detected with the aid of an expression microarray. The five key steps of technology described above formed two important biological processes, namely, the limiting carbon source replacement and secondly, the fermentative production of exogenous proteins. The biological phenomena involved in these two processes were displayed and analyzed at the transcriptional level. In addition to this, with regard to the most important function in the fermentation process of Pichia pastoris, oxid-reduction, the metabolic drift process was analyzed and the important genes that might dominate the changes in the metabolic flux were discovered creatively by using the function tree method in this paper. This study was undertaken from the point of view of the transcriptome and the biological phenomena in the fermemntation process of Pichia pastoris. Both of which, were thoroughly explained during this study. The hope is for many more researchers to optimize the strain fermentation process, to produce proteins at the genetic level, as well as providing and obtaining new perspectives and detailed scientific data for the continued development within this field. The transcriptomic changes in the five key technology steps (time points), during the fermentation process of Pichia pastoris would then be detected with the aid of an expression microarray.

Project description:Background:2,3-butanediol (2,3-BD) is a bulk platform chemical with various potential applications such as aviation fuel. 2,3-BD has three optical isomers: (2R, 3R)-, (2S, 3S)- and meso-2,3-BD. Optically pure 2,3-BD is a crucial precursor for the chiral synthesis and it can also be used as anti-freeze agent due to its low freezing point. 2,3-BD has been produced in both native and non-native hosts. Several pathogenic bacteria were reported to produce 2,3-BD in mixture of its optical isomers including Klebsiella pneumoniae and Klebsiella oxytoca. Engineered hosts based on episomal plasmid expression such as Escherichia coli, Saccharomyces cerevisiae and Bacillus subtilis are not ideal for industrial fermentation due to plasmid instability. Results:Pichia pastoris is generally regarded as safe and a well-established host for high-level heterologous protein production. To produce pure (2R, 3R)-2,3-BD enantiomer, we developed a P. pastoris strain by introducing a synthetic pathway. The alsS and alsD genes from B. subtilis were codon-optimized and synthesized. The BDH1 gene from S. cerevisiae was cloned. These three pathway genes were integrated into the genome of P. pastoris and expressed under the control of GAP promoter. Production of (2R, 3R)-2,3-BD was achieved using glucose as feedstock. The optical purity of (2R, 3R)-2,3-BD was more than 99%. The titer of (2R, 3R)-2,3-BD reached 12 g/L with 40 g/L glucose as carbon source in shake flask fermentation. The fermentation conditions including pH, agitation speeds and aeration rates were optimized in batch cultivations. The highest titer of (2R, 3R)-2,3-BD achieved in fed-batch fermentation using YPD media was 45 g/L. The titer of 2,3-BD was enhanced to 74.5 g/L through statistical medium optimization. Conclusions:The potential of engineering P. pastoris into a microbial cell factory for biofuel production was evaluated in this work using (2R, 3R)-2,3-BD as an example. Engineered P. pastoris could be a promising workhorse for the production of optically pure (2R, 3R)-2,3-BD.

Project description:Dengue is a mosquito-borne viral disease with a global prevalence. It is caused by four closely-related dengue viruses (DENVs 1-4). A dengue vaccine that can protect against all four viruses is an unmet public health need. Live attenuated vaccine development efforts have encountered unexpected interactions between the vaccine viruses, raising safety concerns. This has emphasized the need to explore non-replicating dengue vaccine options. Virus-like particles (VLPs) which can elicit robust immunity in the absence of infection offer potential promise for the development of non-replicating dengue vaccine alternatives. We have used the methylotrophic yeast Pichia pastoris to develop DENV envelope (E) protein-based VLPs. We designed a synthetic codon-optimized gene, encoding the N-terminal 395 amino acid residues of the DENV-2 E protein. It also included 5' pre-membrane-derived signal peptide-encoding sequences to ensure proper translational processing, and 3' 6× His tag-encoding sequences to facilitate purification of the expressed protein. This gene was integrated into the genome of P. pastoris host and expressed under the alcohol oxidase 1 promoter by methanol induction. Recombinant DENV-2 protein, which was present in the insoluble membrane fraction, was extracted and purified using Ni(2+)-affinity chromatography under denaturing conditions. Amino terminal sequencing and detection of glycosylation indicated that DENV-2 E had undergone proper post-translational processing. Electron microscopy revealed the presence of discrete VLPs in the purified protein preparation after dialysis. The E protein present in these VLPs was recognized by two different conformation-sensitive monoclonal antibodies. Low doses of DENV-2 E VLPs formulated in alum were immunogenic in inbred and outbred mice eliciting virus neutralizing titers >1,1200 in flow cytometry based assays and protected AG129 mice against lethal challenge (p<0.05). The formation of immunogenic DENV-2 E VLPs in the absence of pre-membrane protein highlights the potential of P. pastoris in developing non-replicating, safe, efficacious and affordable dengue vaccine.

Dataset Information

Enabler for process analytical technology implementation in Pichia pastoris fermentation: Fluorescence-based soft sensors for rapid quantitation of product titer.

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Enabler for process analytical technology implementation in <i>Pichia pastoris</i> fermentation: Fluorescence-based soft sensors for rapid quantitation of product titer.

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