摘要
研究环丙沙星对嗜热链球菌(S.thermophilus)grx02生理特性的影响。测定环丙沙星对S.thermophilus grx02的最低抑菌质量浓度(MIC),然后将S.thermophilus grx02分别接种于加入0、1/2 MIC、1/10 MIC和1/50 MIC环丙沙星的MRS液体培养基中,测定其生长曲线和pH值变化,分别以光镜和电镜进行形态学观察,并测定对胞内乳糖代谢关键酶活性的影响。结果显示:嗜热链球菌grx02对环丙沙星的最低抑菌质量浓度为3.89μg/mL,加入1/2 MIC环丙沙星后,嗜热链球菌grx02生长速度和产酸速度均明显降低(P<0.01);加入不同亚抑菌质量浓度(低于MIC)环丙沙星后,菌体形态呈半椭圆形,且荚膜变得薄而致密;加入1/2 MIC环丙沙星后胞内的β-半乳糖苷酶和乳酸脱氢酶酶活力均明显下降,加入1/50 MIC环丙沙星后β-半乳糖苷酶活力下降,而乳酸脱氢酶酶活力反而增大。上述结果表明,在环丙沙星胁迫下,嗜热链球菌启动了相应的应激系统,细胞分裂被抑制,嗜热链球菌生理机制发生了复杂的变化。
To investigate the physiological response of S.thermophilus grx02 to ciprofloxacin,the minimal inhibitory concentration(MIC) of ciprofloxacin on S.thermophilus grx02 was determined.The growth curve and pH changes of S.thermophilus grx02 in MRS broth supplemented with 0,1/2 MIC,1/10 MIC and 1/50 MIC ciprofloxacin were determined.In addition to this,morphological observations under light microscope and transmittance electron microscope(TEM) were conducted,and key enzyme activities involved in intracellular lactose metabolism were assayed in the presence of ciprofloxacin.The results showed that the MIC of ciprofloxacin on S.thermophilus grx02 was 3.89μg/mL.The growth and acid production rate of S.thermophilus grx02 decreased significantly after addition of 1/2 MIC ciprofloxacin.The bacteria became semi-oval and the capsules became thin and compact after addition of different sub-MIC concentrations of ciprofloxacin.The activity of β-galactosidase and lactate dehydrogenase decreased obviously after addition of 1/2 MIC ciprofloxacin.After addition of 1/50 MIC ciprofloxacian,the β-galactosidase activity decreased but lactate dehydrogenase activity increased.In conclusion,our results showed that,under the stress of ciprofloxacin,S.thermophilus turned on some stress response system to inhibit cell division and lead to complex changes in the physiological mechanism.
出处
《食品科学》
EI
CAS
CSCD
北大核心
2011年第23期176-179,共4页
Food Science
基金
国家自然科学基金项目(30871815)
江苏省科技厅科技支撑计划项目(BE2008357)
关键词
环丙沙星
胁迫
嗜热链球菌
生理特性
ciprofloxacin
stress
S.thermophilus
physiological characteristics