The developing trends of livestock production are efficiency availability of phytate phosphorus and abuse of antibiotics. safety and sustainability, which face two major challenges： low As a solution phytases and ant...The developing trends of livestock production are efficiency availability of phytate phosphorus and abuse of antibiotics. safety and sustainability, which face two major challenges： low As a solution phytases and antimicrobial peptides are applied as feed additives. However, phytases and antimicrobial peptides are susceptible to proteases, costly by fermentation and potential toxic to production hosts. We transformed an optimized phytase-lactoferricin fusion gene PhyLfdriven by an en- dosperm-specific promoter Gt13aP and Bar （bialaphos resistance） gene as a selection maker into rice. The Bar and PhyLf genes were integrated into the rice genome, stably inherited and expressed. Their phosphinothricin acetyl transferase （PAT） protein content oftransgenic plants with glufosinate resistance varied between 50.45-93.39 IJg g-l. Fusion protein expressed especially in the seeds of transgenic rice had a summit phytase activity at 32.30 U g-l, which increased by 61.71-fold com- pared to the control/check group （CK） and 7.54-fold compared to un-optimized transgenic plant. The highest inorganic phosphorus （Pi） content of the transgenic seeds reached 13.15 mg g-~, increased by 12.77-fold compared to that of CK. Preliminary antibacterial experiments showed that the enterokinase hydrolysate product of fusion protein could inhibit the growth of Escherichia coil DH5a. These results indicated that the protein PhyLf has the potential to increase availability of feed phytate phosphorus, improve consumer＇s immunity and reduce the use of antibiotics.展开更多
Lactoferricin,a multifunctional peptide located in the N-terminal region of lactoferrin,has a broad-spectrum bacteriostatic activity.It is a promising candidate as a food additive and immune fortification agent and do...Lactoferricin,a multifunctional peptide located in the N-terminal region of lactoferrin,has a broad-spectrum bacteriostatic activity.It is a promising candidate as a food additive and immune fortification agent and does not have the risks associated with drug residues and drug resistance.First,we performed promoter and host cell screening to achieve the recombinant expression of lactoferricin in Pichia pastoris,showing an initial titer of 19.5 mg/L in P.pastoris X-33 using PAOX1 promoter.Second,we constructed a 0030-α hybrid signal peptide by fusing the 0030 signal peptide with the pro-sequence of α-factor secretory signal peptide.This further increased the production of lactoferricin,with a titer of 28.8 mg/L in the fermentation supernatant in the shaking flask.Next,we increased the expression of lactoferricin by fusing it with anionic antioxidant peptides.The neutralization of positive charges yielded a titer of 55.3 mg/L in the shaking flask,and a highest titer of 193.9 mg/L in a 3-L bioreactor.The antimicrobial activity analysis showed that recombinant-expressed lactoferricin exhibited potent antibacterial activity against Escherichia coli,Bacillus subtilis,and Staphylococcus aureus.This study provides a reference for the construction of microbial cell factories capable of efficiently synthesizing antimicrobial peptides.展开更多
基金funded by the National Programme on Research and Development of Transgenic Crops,China(2014ZX08001-003)the Open Research Fund of State Key Laboratory of Hybrid Rice,Hunan Hybrid Rice Research Center,China
文摘The developing trends of livestock production are efficiency availability of phytate phosphorus and abuse of antibiotics. safety and sustainability, which face two major challenges： low As a solution phytases and antimicrobial peptides are applied as feed additives. However, phytases and antimicrobial peptides are susceptible to proteases, costly by fermentation and potential toxic to production hosts. We transformed an optimized phytase-lactoferricin fusion gene PhyLfdriven by an en- dosperm-specific promoter Gt13aP and Bar （bialaphos resistance） gene as a selection maker into rice. The Bar and PhyLf genes were integrated into the rice genome, stably inherited and expressed. Their phosphinothricin acetyl transferase （PAT） protein content oftransgenic plants with glufosinate resistance varied between 50.45-93.39 IJg g-l. Fusion protein expressed especially in the seeds of transgenic rice had a summit phytase activity at 32.30 U g-l, which increased by 61.71-fold com- pared to the control/check group （CK） and 7.54-fold compared to un-optimized transgenic plant. The highest inorganic phosphorus （Pi） content of the transgenic seeds reached 13.15 mg g-~, increased by 12.77-fold compared to that of CK. Preliminary antibacterial experiments showed that the enterokinase hydrolysate product of fusion protein could inhibit the growth of Escherichia coil DH5a. These results indicated that the protein PhyLf has the potential to increase availability of feed phytate phosphorus, improve consumer＇s immunity and reduce the use of antibiotics.
基金supported by the National Natural Science Foundation of China(32021005,32270096)the Fundamental Research Funds for the Central Universities(JUSRP222007,JUSRP622004).
文摘Lactoferricin,a multifunctional peptide located in the N-terminal region of lactoferrin,has a broad-spectrum bacteriostatic activity.It is a promising candidate as a food additive and immune fortification agent and does not have the risks associated with drug residues and drug resistance.First,we performed promoter and host cell screening to achieve the recombinant expression of lactoferricin in Pichia pastoris,showing an initial titer of 19.5 mg/L in P.pastoris X-33 using PAOX1 promoter.Second,we constructed a 0030-α hybrid signal peptide by fusing the 0030 signal peptide with the pro-sequence of α-factor secretory signal peptide.This further increased the production of lactoferricin,with a titer of 28.8 mg/L in the fermentation supernatant in the shaking flask.Next,we increased the expression of lactoferricin by fusing it with anionic antioxidant peptides.The neutralization of positive charges yielded a titer of 55.3 mg/L in the shaking flask,and a highest titer of 193.9 mg/L in a 3-L bioreactor.The antimicrobial activity analysis showed that recombinant-expressed lactoferricin exhibited potent antibacterial activity against Escherichia coli,Bacillus subtilis,and Staphylococcus aureus.This study provides a reference for the construction of microbial cell factories capable of efficiently synthesizing antimicrobial peptides.
