[Objective]In order to improve expression vector of L.lactis at food grade and widen application range of original system.[Method] Taking pNZ8149 as basis,the promoter PnisA of pNZ8149 was inserted L.lactis MG1363 and...[Objective]In order to improve expression vector of L.lactis at food grade and widen application range of original system.[Method] Taking pNZ8149 as basis,the promoter PnisA of pNZ8149 was inserted L.lactis MG1363 and SPusp45 of unknown secretory protein in downstream.Through PCR technology,specific primers were used to delete restriction sites between promoter sequence and signal peptide gene sequence and ensure better distance between SD sequence and start codon to construct secreting expression vector pNZS.The reporter gene gus was recombined into multiple cloning site of pNZS to construct pNZS-gus and L.lactis was transformed by electroporation.10 ng/ml nisin was used for induction culture,then culture solution was conducted GUS staining test.[Result]The new constructed L.lactis N3900/pNZS-gus system could express active GUS protein and GUS protein could be secreted out of cell.[Conclusion]The successful construction of this system lays foundation for secretion expression study of protein and oral vaccine research.展开更多
Sourdough bread is traditionally made fermenting a starter with high-gluten flour and water among other ingredients.However,the stability and safety of naturally fermented sourdough cannot always be fully guaranteed.I...Sourdough bread is traditionally made fermenting a starter with high-gluten flour and water among other ingredients.However,the stability and safety of naturally fermented sourdough cannot always be fully guaranteed.In this study,Lactococcus lactis NZ9700,which actively secretes the bacteriocin nisin,was employed for sourdough fermentation and bread production.Three control groups were established to explore the complex and diverse changes occurring during sourdough fermentation,including a non-acidified dough group,a chemically acidified dough group,and a sourdough group fermented with L.lactis NZ9000(which does not secrete nisin).The results demonstrate that fermentation with L.lactis leads to a rapid increase in colony-forming units(CFU),stabilizing the pH of the sourdough at approximately 4.2 within 12 h.The in situ production of acids,sugars,and other metabolites during sourdough fermentation has a significant impact on the dough’s microstructure.Microstructural analysis reveals that sourdough fermentation results in a more organized gluten network,with the L.lactis NZ9700 group exhibiting a more refined microstructure and fewer prominent starch granules.Furthermore,L.lactis NZ9700 produces stable nisin during fermentation,which persists even after baking,providing continuous antimicrobial protection to the final product.This reduced fungal contamination and extended the shelf life of the bread.Last,the growth of L.lactis NZ9700 during the early stages of fermentation provides more alcohols and ketones to the breads,endowing the sourdough breads with richer and more complex flavor profiles.展开更多
基金Supported by Doctoral Fund of Jilin Agricultural University(20070193005)~~
文摘[Objective]In order to improve expression vector of L.lactis at food grade and widen application range of original system.[Method] Taking pNZ8149 as basis,the promoter PnisA of pNZ8149 was inserted L.lactis MG1363 and SPusp45 of unknown secretory protein in downstream.Through PCR technology,specific primers were used to delete restriction sites between promoter sequence and signal peptide gene sequence and ensure better distance between SD sequence and start codon to construct secreting expression vector pNZS.The reporter gene gus was recombined into multiple cloning site of pNZS to construct pNZS-gus and L.lactis was transformed by electroporation.10 ng/ml nisin was used for induction culture,then culture solution was conducted GUS staining test.[Result]The new constructed L.lactis N3900/pNZS-gus system could express active GUS protein and GUS protein could be secreted out of cell.[Conclusion]The successful construction of this system lays foundation for secretion expression study of protein and oral vaccine research.
基金supported by National Natural Science Foundation of China(32472299)Natural Science Fund of Anhui Province(2408085MC082)+2 种基金Major Project of Science and Technology of Anhui Province(202423m10050005)Major Project of Science and Technology of Suzhou(SZKJXM202315)Fundamental Research Funds from Yuexi Xingyue Industrial Investment Co.,Ltd(W2023JSKF0788).
文摘Sourdough bread is traditionally made fermenting a starter with high-gluten flour and water among other ingredients.However,the stability and safety of naturally fermented sourdough cannot always be fully guaranteed.In this study,Lactococcus lactis NZ9700,which actively secretes the bacteriocin nisin,was employed for sourdough fermentation and bread production.Three control groups were established to explore the complex and diverse changes occurring during sourdough fermentation,including a non-acidified dough group,a chemically acidified dough group,and a sourdough group fermented with L.lactis NZ9000(which does not secrete nisin).The results demonstrate that fermentation with L.lactis leads to a rapid increase in colony-forming units(CFU),stabilizing the pH of the sourdough at approximately 4.2 within 12 h.The in situ production of acids,sugars,and other metabolites during sourdough fermentation has a significant impact on the dough’s microstructure.Microstructural analysis reveals that sourdough fermentation results in a more organized gluten network,with the L.lactis NZ9700 group exhibiting a more refined microstructure and fewer prominent starch granules.Furthermore,L.lactis NZ9700 produces stable nisin during fermentation,which persists even after baking,providing continuous antimicrobial protection to the final product.This reduced fungal contamination and extended the shelf life of the bread.Last,the growth of L.lactis NZ9700 during the early stages of fermentation provides more alcohols and ketones to the breads,endowing the sourdough breads with richer and more complex flavor profiles.
