Cronobacter spp.has strong resistance to desiccation and high permeability in Enterobacteriaceae,and powdered infant formula(PIF)is one of the main contamination routes.In recent years,the contamination of Cronobacter...Cronobacter spp.has strong resistance to desiccation and high permeability in Enterobacteriaceae,and powdered infant formula(PIF)is one of the main contamination routes.In recent years,the contamination of Cronobacter spp.in PIF incidents occurs from time to time,causing infant serious diseases or death.In this investigation,matrix-assisted laser desorption/ionization time of flight mass spectrometry was used to identify the phenotypes of 35 Cronobacter strains isolated from PIF and its processing environment.Subsequently,the isolates were evaluated for drying and osmotic pressure tolerance.The results showed that the deactivation rate of the strains ranged from 9.01%to 77.57%,and the highest osmotic pressure condition the strains could tolerate was 6 g/100 mL Na Cl.In addition,there was a positive correlation between biofilm formation ability and desiccation resistance.Combined with transcriptomics,Cronobacter spp.could activate biofilm synthesis,produce more trehalose,accumulate betaine and electrolytes to stabilize intracellular structure under the two treatment conditions.A total of 31 and 43 genes were found related to desiccation and permeability resistance,respectively.And some genes(cysM,thuF,ycjO,etc.)were found to be associated with two tolerances for the first time.展开更多
从冷冻菌种甘油管中分离到一株生长力极强的污染细菌,该细菌能产生抑制链格孢真菌的活性物质,在研究抑菌活性物质的过程中,对这株细菌进行分类鉴定.通过传统的表型及生理生化方法,将该菌定位到芽孢杆菌属(Bacillus),与枯草芽孢杆菌(B.su...从冷冻菌种甘油管中分离到一株生长力极强的污染细菌,该细菌能产生抑制链格孢真菌的活性物质,在研究抑菌活性物质的过程中,对这株细菌进行分类鉴定.通过传统的表型及生理生化方法,将该菌定位到芽孢杆菌属(Bacillus),与枯草芽孢杆菌(B.subtilis)的相似性最大,最终确定这株菌为B.subtilis中的一个株型,即Bacillus subtilis subsp.subtilis str.168.以链格孢属真菌(包括原有的和从空气、小麦病斑分离的)为受试菌,对此株细菌产生抑菌物质的时间进行跟踪,当该菌进入稳定生长期后开始产生抑菌物质,72 h时积累达到最大值.对抑菌物质进行过滤、加热、调节pH值等多种处理,初步确定抑菌物质的特性为外泌型、脂溶性,可透过孔径0.22μm的微孔滤膜,可耐受100℃5 m in,80℃10 m in的高温,微碱性条件不影响其生物活性.展开更多
为了比较具有凝乳功能的Paenibacillus spp.BD3526来源的金属蛋白酶与基因重组凝乳酶对乳蛋白水解位点的差异,采用BD3526金属蛋白酶和凝乳酶对α_(s1)-酪蛋白(casein,CN)、α_(s2)-CN、β-乳球蛋白(lactoglobulin,Lg)和κ-CN进行酶解,...为了比较具有凝乳功能的Paenibacillus spp.BD3526来源的金属蛋白酶与基因重组凝乳酶对乳蛋白水解位点的差异,采用BD3526金属蛋白酶和凝乳酶对α_(s1)-酪蛋白(casein,CN)、α_(s2)-CN、β-乳球蛋白(lactoglobulin,Lg)和κ-CN进行酶解,分别对不同时间的酶解产物采用高效液相色谱与四极杆飞行时间串联质谱(high performance liquid chromatography of quadrupole time of flight-tandem mass spectrometry,HPLC-Q-TOF-MS/MS)进行分析。结果表明:BD3526金属蛋白酶与凝乳酶在对乳蛋白的水解位点上具有较高的相似性,前者对α_(s1)-CN、α_(s2)-CN、β-Lg和κ-CN水解能力较后者弱,对P1为K(Lys)、R(Arg)且P1'为T(Thr)、F(Phe)和Y(Tyr)间的肽键水解特异性很高,并主要水解K-T(Lys-Thr)、K-F(Lys-Phe)、R-F(Arg-Phe)、R-Y(Arg-Tyr)肽键,水解生成的肽具有血管紧张素转换酶(angiotensin converting enzyme,ACE)抑制、抗菌、免疫调节等功能。展开更多
基金supported by the Joint Funds of the National Natural Science Foundation of China(U21A20272)。
文摘Cronobacter spp.has strong resistance to desiccation and high permeability in Enterobacteriaceae,and powdered infant formula(PIF)is one of the main contamination routes.In recent years,the contamination of Cronobacter spp.in PIF incidents occurs from time to time,causing infant serious diseases or death.In this investigation,matrix-assisted laser desorption/ionization time of flight mass spectrometry was used to identify the phenotypes of 35 Cronobacter strains isolated from PIF and its processing environment.Subsequently,the isolates were evaluated for drying and osmotic pressure tolerance.The results showed that the deactivation rate of the strains ranged from 9.01%to 77.57%,and the highest osmotic pressure condition the strains could tolerate was 6 g/100 mL Na Cl.In addition,there was a positive correlation between biofilm formation ability and desiccation resistance.Combined with transcriptomics,Cronobacter spp.could activate biofilm synthesis,produce more trehalose,accumulate betaine and electrolytes to stabilize intracellular structure under the two treatment conditions.A total of 31 and 43 genes were found related to desiccation and permeability resistance,respectively.And some genes(cysM,thuF,ycjO,etc.)were found to be associated with two tolerances for the first time.
文摘从冷冻菌种甘油管中分离到一株生长力极强的污染细菌,该细菌能产生抑制链格孢真菌的活性物质,在研究抑菌活性物质的过程中,对这株细菌进行分类鉴定.通过传统的表型及生理生化方法,将该菌定位到芽孢杆菌属(Bacillus),与枯草芽孢杆菌(B.subtilis)的相似性最大,最终确定这株菌为B.subtilis中的一个株型,即Bacillus subtilis subsp.subtilis str.168.以链格孢属真菌(包括原有的和从空气、小麦病斑分离的)为受试菌,对此株细菌产生抑菌物质的时间进行跟踪,当该菌进入稳定生长期后开始产生抑菌物质,72 h时积累达到最大值.对抑菌物质进行过滤、加热、调节pH值等多种处理,初步确定抑菌物质的特性为外泌型、脂溶性,可透过孔径0.22μm的微孔滤膜,可耐受100℃5 m in,80℃10 m in的高温,微碱性条件不影响其生物活性.
文摘为了比较具有凝乳功能的Paenibacillus spp.BD3526来源的金属蛋白酶与基因重组凝乳酶对乳蛋白水解位点的差异,采用BD3526金属蛋白酶和凝乳酶对α_(s1)-酪蛋白(casein,CN)、α_(s2)-CN、β-乳球蛋白(lactoglobulin,Lg)和κ-CN进行酶解,分别对不同时间的酶解产物采用高效液相色谱与四极杆飞行时间串联质谱(high performance liquid chromatography of quadrupole time of flight-tandem mass spectrometry,HPLC-Q-TOF-MS/MS)进行分析。结果表明:BD3526金属蛋白酶与凝乳酶在对乳蛋白的水解位点上具有较高的相似性,前者对α_(s1)-CN、α_(s2)-CN、β-Lg和κ-CN水解能力较后者弱,对P1为K(Lys)、R(Arg)且P1'为T(Thr)、F(Phe)和Y(Tyr)间的肽键水解特异性很高,并主要水解K-T(Lys-Thr)、K-F(Lys-Phe)、R-F(Arg-Phe)、R-Y(Arg-Tyr)肽键,水解生成的肽具有血管紧张素转换酶(angiotensin converting enzyme,ACE)抑制、抗菌、免疫调节等功能。
