An enzyme-displaying yeast as a whole-cell biocatalyst is an alternative to immobilized enzyme, due to its low-cost preparation and simple recycle course. Here, lipase-displaying Pichia pastoris whole-cell was used as a biocatalyst to synthesize diisooctyl adipate in the non-aqueous system. The maximum productivity of diisooctyl adipate was obtained as 85.0% in a 10 mL reaction system. The yield could be reached as high as 97.8% when the reaction system was scaled up to 200 mL. The purity obtained is 98.2% after vacuum distillation. Thus, the lipase-displaying P. pastoris whole-cell biocatalyst was promising in commercial application for diisooctyl adipate synthesis in non-aqueous phase.
Adipates ; metabolism ; Industrial Microbiology ; Lipase ; metabolism ; Pichia ; metabolism

In industrial fermentation processes, bacteria have to adapt environmental stresses. Sometimes, such a self-adaption does not work and will cause fermentation failures, although such adaptation also can generate unexpected positive effects with improved fermentation performance. Our review introduces cell self-adaption to environmental variations or stress, process optimization based on such self-adaptions, with heterologous proteins production by Pichia pastoris and butanol fermentation as examples. Our review can sever as reference for fermentation optimization based on cell self-adaption.
Adaptation, Physiological ; Butanols ; metabolism ; Environment ; Fermentation ; Pichia ; cytology ; metabolism

Chemostat culture was performed to characterize the growth, substrate consumption and the hirudin production, and to disclose their interrelations in the fermentation of recombinant Pichia pastoris. The Andrew substrate-inhibited growth model is more suitable than Monod model to simulate the growth of Pichia pastoris on methanol. Therefore, two stationary states can be obtained in the continuous culture at a certain dilution rate because of the substrate inhibition on cell growth. The stationary state could be obtained if only the dilution rate not more than 0.048 h(-1) in the continuous fermentation. The concentrations of cell, methanol and hirudin were constant after 50 h continuous culture with dilution rate at 0.04 h(-1). However, it could not be obtained when the dilution rate more than 0.048 h(-1) because the other stationary point at S > 0.048 h(-1) is unstable. Therefore, it was found that the cell concentration declined and the methanol concentration increased from 2.9 g/L to 18.1 g/L within 18h at dilution rate 0.06 h(-1). Thus, the fed-batch culture with a constant specific growth rate was carried out to disclose the fermentation behavior at high and constant methanol concentration in aid of a methanol sensor. The theoretical maximum specific growth rate, microm = 0.0464 h(-1), was found under critical methanol concentration, Scrit = 3.1 g/L. The growth of P. pastoris was typically methanol-limited at the methanol concentration S < Scrit. It was, however, inhibited at S > Scrit. The maximum specific Hir65 production rate qp was obtained at 0.2 mg/(g x h) when methanol concentration and mu were 0.5 g/L and 0.02 h(-1), respectively. The specific Hir65 production rate qp increased with the increase of mu and S at mu < 0.02 h(-1), and decreased at mu > 0.02 h(-1). The specific methanol consumption rate increased with the increase of S when S < 5 g/L, but decreased when S > 5 g/L. At last, the high Hir65 production rate 0.2 mg/(g x h) was obtained in the fermentation conducted under methanol-limited concentration and mu controlled at 0.5 g/L and 0.02 h(-1), respectively, while the specific methanol consumption rate is low only at 0.04 g/(g x h), showing the potential for the strategy of getting high Hir65 production rate at the low consumption of methanol.
Fermentation ; physiology ; Hirudins ; metabolism ; Methanol ; metabolism ; Pichia ; growth & development ; metabolism ; Recombination, Genetic

OBJECTIVEThe purpose of this study is to express partial S gene of Hantavirus Z10.

METHODSThe 300 bp S gene of Z10 strain was synthesized by using a successive PCR method for the optimal expression in Pichia pastoris and subcloned into pMD19-T. The SP300 gene was constructed into pPICZaA and sequenced. The recombinant pPICZaA-SP300 and pPICZaA-S300 was transformed into Pichia with LiCI.

RESULTSThe recombination Pichia were cultivate, and expressed the SP300 or S300 gene induced in Pichia by methanol.

CONCLUSIONThe nucleocapsid secreted from the Pichia can be detected by ELISA and WesternBlot.

Gene Expression ; Hantavirus ; genetics ; metabolism ; Nucleocapsid Proteins ; genetics ; metabolism ; Pichia ; genetics ; metabolism

Glucose oxidase (GOD) is an important industrial enzyme with many potential applications. In order to increase the production and productivity of GOD by recombinant Pichia pastoris GS115, we investigated the feeding strategies of mixed carbon sources during induction phase, based on results of the optimization of initial cell and methanol concentration on GOD production. The optimal initial cell and methanol concentration were 100 g/L and 18 g/L. During induction phase, the mixed-carbon-sources strategies showed that glycerol, sorbitol or mannitol co-feeding with methanol could enhance GOD production. With mannitol co-feeding (20:1(W/W)), the maximum GOD production and maximum GOD productivity reached 711.3 U/mL and 4.60 U/(mL x h) after an induction period of 156 h. Compared to the control, the enhancements of GOD production and productivity were 66.3% and 67.9%, respectively. Meanwhile, we found an appropriate mannitol co-feeding strategy that would not inhibit the expression of promote. The activity of alcohol oxidase was 8.8 U/g, which was enhanced by 69.2% compared to the control (5.2 U/g). We can use the same optimization process to improve the production of other proteins from recombinant Pichia pastoris by changing the fermentation parameters.
Carbon ; metabolism ; Fermentation ; Glucose Oxidase ; biosynthesis ; Glycerol ; metabolism ; Industrial Microbiology ; Mannitol ; metabolism ; Methanol ; metabolism ; Pichia ; metabolism ; Sorbitol ; metabolism

A recombinant strain of Pichia pastoris with a phenotype of Muts was used to produce angiostatin in a 5-L fermentor. The methanol utilization ability of the present strain was weak, which resulted in extremely low growth rate and angiostatin productivity during the expression phase with methanol as the sole carbon source. To enhance the cell density and angiostatin expression level, mixed-carbon-source of glycerol-methanol was used in the expression phase. The methanol concentration was well controlled at 5 g/L by a methanol sensor and control system, and glycerol was continuously fed into the fermentor to achieve a higher cell density. 120 g/L of cells and 39 mg/L of angiostatin were reached at the end of fermentation which lasted 110 h. The mean specific cell growth rate in the expression phase was 0.01 h(-1), and the mean specific angiostatin productivity was 0.006 mg/(g x h). According to the data obtained in several runs of fermentation in which glycerol was fed at different rates, a higher mean specific angiostatin productivity was reached at the mean specific cell growth rate of 0.012 h(-1). To avoid the repression of angiostatin expression caused by residual glycerol and ethanol accumulation due to overfeeding of glycerol, glycerol addition was controlled to produce continuous oscillations in dissolved oxygen, because the change of dissolved oxygen concentration could deliver the information of available carbon source in the fermentation broth. Controlled glycerol feeding also avoided the problem of oxygen limitation brought by high cell density, and thus decreased the cooling requirement of the fermentor. Cell density reached 150 g/L at the end of fermentation, and angiostatin level reached 108 mg/L after an expression period of 96 h when the mean specific growth rate was maintained at 0.012 h(-1) by using the glycerol feeding strategy to result in the oscillations in dissolved oxygen. The mean specific angiostatin productivity was improved to 0.02 mg/(g x h). The apparent cell yield on glycerol and methanol were respectively 0.69 g/g and 0.93 g/g, higher than those in the fermentation without using the feeding strategy with dissolved oxygen as the indicator of metabolism.
Angiostatins ; genetics ; metabolism ; physiology ; Biotechnology ; methods ; Carbon ; metabolism ; Fermentation ; physiology ; Glycerol ; metabolism ; Methanol ; metabolism ; Oxygen ; metabolism ; Pichia ; genetics ; metabolism

To utilize Pichia pastoris to produce S-adenosyl-L-methionine (SAM), an intracellular expression vector harboring S. cerevisiae SAM2 was transformed into GS115. A recombinant strain having 2 copies of expression cassette was obtained through G418 resistance screening. This strain had higher SAM synthetase activity and higher SAM production capacity than the original strain, when cultured in medium containing methanol and methionine. The carbon source and nitrogen source of medium was optimized. The results showed SAM production by this strain was closely related to carbon metabolism. With supplementation of 0.2% glycerol every day from the beginning of 3rd day, this strain produced 1.58 g/L SAM when cultured in a medium containing 0.75% L-methionine and optimized carbon and nitrogen source after 6 days.
Methionine Adenosyltransferase ; genetics ; metabolism ; Pichia ; genetics ; Recombinant Proteins ; metabolism ; S-Adenosylmethionine ; biosynthesis

To compare the DAAO expression level in different Pichia pastoris host strains, the gene encoding DAAO from Trigonopsis variabilis was cloned into plasmid pPIC3.5k and then transformed into P. pastoris GS115 and KM71 respectively. The positive transformants PDK13 (MutS) and PD27 (Mut+) were obtained by PCR analysis. Their optimal and different expression conditions were investigated. To compare with PD27, PDK13 was determined to poss a slower consumption of methanol, a longer induction time, a lower oxygen request and apparently higher expression of DAAO. The highest expression levels were reached up to 2700, 2500 IU/L in shaking flask and 10140, 8463.5 IU/L in fermentor respectively. The over-expression of DAAO can meet its large demand for production of 7-ACA, alpha-keto acid and L-amino acid. In addition, the phenylpyruvate and L-phenylalanine were obtained by crude DAAO reacting with DL-phenylalanine at 37 degrees C for 3h.
D-Amino-Acid Oxidase ; genetics ; Fermentation ; Methanol ; metabolism ; Phenylalanine ; metabolism ; Pichia ; genetics ; Polymerase Chain Reaction

In Pichia pastoris fermentation, methanol was oxidized into carbon oxide and produced a byproduct H2 O2, one of the partially reduced forms of molecular oxygen known as reactive oxygen species (ROS) . ROS are highly damaging towards cellular constituents. Flow cytometry (FCM) is an excellent method that permits the rapid, optical analysis of individual cells and has many advantages over conventional cytometry. However, its use in detecting intracellular ROS levels during Pichia fermentation was rarely reported. In our work, by means of flow cytometry, two fluorescent dye 2', 7'-dichlorofluorescin diacetate (DCFH-DA) and propidium iodide (PI) were used to detect ROS. The effect of intracellular ROS on Pichia pastoris cells during fermentation was studied through the comparison between DCFH-DA/PI double-stained cells and PI single-stained cells. In this study, the loss of cell viability during fermentation was correlated with the accumulation of ROS. At the glycerol batch and fed-batch phase, little ROS was accumulated intracellularly and cell viability reached almost 100%. At the early methanol fed-batch phase, intracellular ROS accumulation took place but 98.5% cells still kept viable. At the later methanol fed-batch phase, 94.0% cells accumulated high ROS. As a result, some cells lost their viability because of the damage of ROS. 25.4% dead cells accumulated high ROS in the total 29.1% dead cells.
Bioreactors ; microbiology ; Fermentation ; Flow Cytometry ; Pichia ; metabolism ; physiology ; Reactive Oxygen Species ; metabolism

A new method to express oligomerized feruloyl esterase (FAE) in Pichia pastoris GS115 to improve the catalytic efficiency was developed. It was realized by fusing the foldon domain at the C-terminus of FAE, and the fusion protein was purified by histidine tag. Fusion of the feruloyl esterase with the foldon domain resulted spontaneously forming a trimer FAE to improve the catalytic performance. The oligomerized FAE and monomeric FAE were obtained by purification. The apparent molecular weight of the oligomerized FAE was about 110 kDa, while the monomeric FAE about 40 kDa, and the optimum temperature of the oligomerized FAE was 50 °C, which is the same as the monomeric one. The optimal pH of the oligomerized FAE is 5.0, while the optimal pH of the monomer FAE is 6.0. When compared with the monomeric ones, the catalytic efficiency (kcat/Km) of the oligomerized FAE increased 7.57-folds. The catalytic constant (kcat) of the oligomerized FAE increased 3.42-folds. The oligomerized FAE induced by foldon have advantages in the catalytic performances, which represents a simple and effective enzyme-engineering tool. The method proposed here for improving the catalytic efficiency of FAE would have great potentials for improving the catalytic efficiency of other enzymes.
Carboxylic Ester Hydrolases ; metabolism ; Catalysis ; Molecular Weight ; Pichia ; genetics ; metabolism ; Polymerization ; Protein Engineering ; Substrate Specificity