LlaBIII,isolated from the naturally occurring plasmid pJW566 from Lactococcus lactis subsp.cremoris W56,encoded a restriction and modification (R/M) system. The plasmid pJK1 carrying the R/M system LlaBIII was transfo...LlaBIII,isolated from the naturally occurring plasmid pJW566 from Lactococcus lactis subsp.cremoris W56,encoded a restriction and modification (R/M) system. The plasmid pJK1 carrying the R/M system LlaBIII was transformed into L.lactis IL1403 with type I R/M system located on chromosome and the strain MG1614[pAW601] with AbiS gene on plasmid pAW601, respectively. The transformants obtained showed stacking resistance against bacteriophages. The plasmid pJK1 was transformed into industrial strains L.lactis SMQ86 and CHCC2281,the transformants showed the EOP of the bacteriophages decreased by 10 -3 and 10 -5, respectively.The results indicated that the R/M system LlaBIII could protect strains from bacteriophages in dairy fermentation.展开更多
为了研究胰蛋白酶限制性修饰对乳清浓缩蛋白(WPC)热致聚合物的微观形态及表面性质的影响,本文制备了胰蛋白酶在不同水解度(DH为0.2%、0.6%和1%)限制性修饰后的WPC在p H 2.0、90℃下热致聚合物,利用透射电镜分析了聚合物的微观形态特征,...为了研究胰蛋白酶限制性修饰对乳清浓缩蛋白(WPC)热致聚合物的微观形态及表面性质的影响,本文制备了胰蛋白酶在不同水解度(DH为0.2%、0.6%和1%)限制性修饰后的WPC在p H 2.0、90℃下热致聚合物,利用透射电镜分析了聚合物的微观形态特征,测定了不同聚合物的表面性质。结果表明,纤维聚合物较常规p H条件下形成的无定形聚合物具有较差的乳化活性和乳化稳定性以及较优的起泡和泡沫稳定性。胰蛋白酶修饰促进WPC纤维聚合物的形成,乳化活性较天然WPC形成纤维稍有提高;起泡性和泡沫稳定性显著提高,在DH为0.6%时起泡提高幅度最大,较天然WPC纤维提高了11.76%;在DH为1%时,泡沫稳定性较天然WPC纤维提高了12.59%。WPC经胰蛋白酶修饰后所形成更优的纤维结构以及表面疏水性的提高有利于其界面性质的提高。展开更多
文摘LlaBIII,isolated from the naturally occurring plasmid pJW566 from Lactococcus lactis subsp.cremoris W56,encoded a restriction and modification (R/M) system. The plasmid pJK1 carrying the R/M system LlaBIII was transformed into L.lactis IL1403 with type I R/M system located on chromosome and the strain MG1614[pAW601] with AbiS gene on plasmid pAW601, respectively. The transformants obtained showed stacking resistance against bacteriophages. The plasmid pJK1 was transformed into industrial strains L.lactis SMQ86 and CHCC2281,the transformants showed the EOP of the bacteriophages decreased by 10 -3 and 10 -5, respectively.The results indicated that the R/M system LlaBIII could protect strains from bacteriophages in dairy fermentation.
基金the National Natural Science Foundation of China(No.31000028)the Sichuan Key Technology R&D Program(No.2009NZ00045)+1 种基金the Sci-Tech Fund Project of Chinese Academy of Agricultural Sciences(2009and 2011)the National Science and Technology Pillar Program of China(No.2007BAC18B04)~~
文摘为了研究胰蛋白酶限制性修饰对乳清浓缩蛋白(WPC)热致聚合物的微观形态及表面性质的影响,本文制备了胰蛋白酶在不同水解度(DH为0.2%、0.6%和1%)限制性修饰后的WPC在p H 2.0、90℃下热致聚合物,利用透射电镜分析了聚合物的微观形态特征,测定了不同聚合物的表面性质。结果表明,纤维聚合物较常规p H条件下形成的无定形聚合物具有较差的乳化活性和乳化稳定性以及较优的起泡和泡沫稳定性。胰蛋白酶修饰促进WPC纤维聚合物的形成,乳化活性较天然WPC形成纤维稍有提高;起泡性和泡沫稳定性显著提高,在DH为0.6%时起泡提高幅度最大,较天然WPC纤维提高了11.76%;在DH为1%时,泡沫稳定性较天然WPC纤维提高了12.59%。WPC经胰蛋白酶修饰后所形成更优的纤维结构以及表面疏水性的提高有利于其界面性质的提高。
