对羟基苯甲酸壳聚糖酯的抑菌活性研究

试验结果表明对羟基苯甲酸壳聚糖酯具有广谱的抑菌活性,无论是革兰氏阴性菌或阳性菌,还是酵母菌和霉菌,该酯都有很强的抑菌效果。对羟基苯甲酸壳聚糖酯对金黄色葡萄球菌和大肠杆菌的MIC(minimum inhibi-tory concentrations)值分别达到了0.01%和0.025%。对羟基苯甲酸壳聚糖酯在更大的pH值(pH4～10)范围内呈现强烈的抑菌活性,比反应物壳聚糖(pH6.0以下)的应用范围更宽;由于壳聚糖结构单元上存在游离氨基的缘故,所以对羟基苯甲酸壳聚糖酯在酸性环境下对细菌的抑菌活性优于在碱性环境中。对羟基苯甲酸壳聚糖酯的热稳定性良好。在苹果汁和肉汁食品体系中,对羟基苯甲酸壳聚糖酯仍表现出强烈的抑菌活性。     

Short communication: Antimicrobial resistance and virulence genes of Enterococcus faecalis isolated from subclinical bovine mastitis cases in China

This study aimed to investigate the antimicrobial resistance and virulence genes of Enterococcus faecalis isolated from subclinical bovine mastitis cases in China. Enterococcus faecalis isolates were identified by 16S rRNA amplification and sequencing. Antimicrobial susceptibility was determined by the disc diffusion method. Antimicrobial resistance and virulence genes were tested by PCR. Overall, E. faecalis was recovered from 81 of 1,787 (4.5%) mastitic milk samples. The isolates showed high resistance against tetracycline (87.7%) and erythromycin (79.0%). The most prevalent resistance genes found in the E. faecalis were tetK (96.3%), tetL (79.0%), and tetM (87.7%) for tetracycline and ermC (97.5%) for erythromycin. Moreover, gelE (70.4%), esp (85.2%), efaA (91.4%) were the most common virulence genes. This is the first report to characterize E. faecalis recovered from subclinical bovine mastitis cases in China.     

不同分子量分布的美拉德产物的呈味特性及抗氧化抗菌活性研究

通过超滤及葡聚糖凝胶色谱技术结合将美拉德产物按分子量大小分级成三个组分,即小于1000u、1000～5000u和大于5000u,并评价其在清汤中的风味特性、清除DPPH自由基的能力及对金黄色葡萄球菌、李斯特菌、大肠杆菌和沙门氏菌的抑制活性。结果显示,1000～5000u的美拉德产物增强风味的效果最显著,其次是小于1000u的产物,这两种产物对DPPH自由基清除率分别达80%和72%,对四种菌的最低抑制浓度达25～75mg/mL。大于5000u的美拉德产物在较低浓度下清除率达90%,对四种菌的最低抑制浓度为6.25～25mg/mL,且对金黄色葡萄球菌的抑制效果最强,最低抑制浓度达6.25mg/mL。     

苦瓜汁的抑菌活性及其热稳定性的研究

采用琼脂扩散法研究了苦瓜汁对大肠杆菌、金黄色葡萄球菌、枯草芽孢杆菌、沙门氏菌的抑菌活性。研究结果表明:苦瓜汁对四种菌均具有较好的抑菌活性,其中对大肠杆菌和沙门氏菌的抑菌活性明显强于对金黄色葡萄球菌和枯草芽孢杆菌的抑菌活性;在100℃以内,苦瓜汁具有良好的抑菌稳定性。     

超滤解淀粉芽孢杆菌发酵液提取抗菌物质的研究

对解淀粉芽孢杆菌(BacillusamyloliquefaciensQ-12)的发酵培养获得具有活性的抗菌物质,对其发酵液中抗菌物质的提取采用截留分子量为70000的双酚A型聚砜中空纤维膜超滤。结果表明在室温、膜两侧压差0.02～0.03MPa、料液体积流量为16L/h时超滤,抗菌活性物质均截留在浓缩液中,超滤浓缩的体积比为4.6%～5.6%。清洗后的膜通量可恢复至94%以上。     

Phenotypic Characterization and Genotypic Subtyping of Salmonella enterica Serovars Enteritidis and Gallinarum Isolated from Human and Poultry-Related Samples

This study aimed to assess the serotypes, antibiotic susceptibility, and molecular subtyping of Salmonella enterica isolated from food products and human patients with gastroenteritis. A total of 59 isolates were investigated, and the results revealed a predominance of S. Enteritidis with 57.63% (34/59) S. Gallinarum held second with 15.62% (5/32) of total food borne. While, isolates from humans showed 18.51% (5/27) of S. Typhimurium. High level of resistance to nalidixic acid was noted among food strains and 35.29% of human isolates were found to be multidrug resistant. Eight representative isolates were subtyping using three molecular approaches, ribotyping, Multilocus sequence typing (MLST) and Multiple-locus variable number tandem repeat analysis (MLVA). MLST showed three sequence types corresponding to two clonal complexes, (ST-78, CC-4) for S. Gallinarum, (ST-11, CC-4) for S. Enteritidis and (S-367, CC-37) for S. Cerro. While, MLVA generated six different profiles targeting nine loci for S. Enteritidis and S. Gallinarum.     

枫香叶正丁醇提取物抑菌效果及其抗氧化活性研究

采用打孔法测定抑菌圈大小和试管连续稀释法测定最小抑菌浓度(MIC),研究了枫香叶正丁醇提取物抑菌效果,并测定其对DPPH自由基、超氧阴离子自由基和羟自由基的清除活性。结果表明:枫香叶正丁醇提取物对7种实验菌均有抑制作用,不同浓度间、不同菌种间存在极显著(p0.01)差异;且对细菌的抑制作用强于真菌,对革兰氏阴性菌的抑菌效果比革兰氏阳性菌好;对大肠杆菌、枯草杆菌、金黄色葡萄球菌、四联球菌、黄曲霉、黑曲霉、青霉的MIC分别为3.1、12.5、12.5、6.25、12.5、25、12.5mg/m L。枫香叶正丁醇提取物具有较强的的抗氧化活性,可作为功能性食品资源开发利用。     

羊奶粉生产环节阪崎肠杆菌分离鉴定及其毒力基因和药敏检测

目的:分析羊奶粉生产环节阪崎肠杆菌的污染状况,分离株毒力基因携带情况以及耐药性。方法:采自某羊奶粉加工厂空气过滤车间、液态奶车间、流化床车间、喷雾干燥车间和包装车间的生产样品及环境样品共180份,按国标GB4789.40-2010和PCR方法进行阪崎肠杆菌的分离鉴定;采用PCR方法检测cpa、hly、sip和omp X毒力基因;采用琼脂稀释法测定药敏性。结果:27个采样点中有14个阪崎肠杆菌阳性点,检出率为51.9%;180份样品中有29份检出阪崎肠杆菌,污染率为16.1%;阳性样品主要为粉状和棉签涂抹样品,污染率分别为23.5%和16.9%。毒力基因检出率为100%,毒力基因类型有cpa-omp X和cpa-hly-omp X,检出率分别为79.3%,20.7%。29株菌对利福平、甲氧苄啶/磺胺甲恶唑、头孢西丁钠、阿莫西林、阿莫西林/克拉维酸的耐药率依次为100%,75.9%,6.9%,3.4%和3.4%;对其它11种抗生素均敏感,多重耐药率为6.9%。结论:羊奶粉加工厂存在阪崎肠杆菌的污染。空气流动、粉尘污染、操作人员交叉污染及生产设备清洗消毒不彻底可能是加工过程中该菌的污染途径。分离株毒力基因携带率较高,对大多数供试抗生素敏感,出现多重耐药现象。     

全涤珊瑚绒针织物纳米银抗菌整理技术

介绍了一种纳米银多巴胺固体微球的乳液的制备方法,以及这类乳液在全涤珊瑚绒针织面料的长效抗菌整理中的应用。本研究采用环氧丙烷与环氧乙烷的共聚物Pluronic F-127作为还原剂和分散剂,负载纳米银离子,然后通过熔融喷涂,将负载纳米银离子的Pluronic F-127微球用石蜡保护起来,最后和多巴胺复配．配制成用于全涤珊瑚绒针织面料的抗菌整理乳液。实验结果表明,经这类纳米银多巴胺固体微球的乳液处理的全涤珊瑚绒针织面料具有优异的耐久抗菌效果。     

南五味子乙醇提取物对食品腐败细菌的抑菌活性研究

目的:研究南五味子乙醇提取物的体外抑菌活性,以期为寻求新的天然食品防腐剂提供实验依据。方法:以抑菌圈直径、最低有效抑菌浓度等为指标,以金黄色葡萄球菌、乙型副伤寒沙门氏菌等7种食品腐败细菌作为供试菌,研究南五味子乙醇提取物的体外抗菌活性。结果:南五味子乙醇提取物对供试菌的抑菌圈直径均>20mm,且对革兰氏阳性细菌的抑制效果强于革兰氏阴性细菌。乙醇提取物对供试菌的MIC值和MBC值分别为金黄色葡萄球菌3.125,6.25mg/mL,蜡样芽孢杆菌1.562,3.125mg/mL,大肠杆菌25,25mg/mL,变形杆菌12.5,25mg/mL,枯草芽孢杆菌、乙型副伤寒沙门氏菌、宋内氏志贺氏菌、铜绿假单胞菌的MIC值和MBC值均为12.5mg/mL。提取物对供试菌的抑菌率随抑菌作用时间的延长,提取物浓度的增加而升高。提取物对蜡样芽孢杆菌抑菌能力大于苯甲酸钠和山梨酸钾;对金黄色葡萄球菌的抑菌能力与苯甲酸钠相同,稍差于山梨酸钾。结论:南五味子乙醇提取物对食品腐败细菌具有显著的抑菌活性,有望开发成天然食品防腐剂。