• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文学位 >Persistence of microbiological agents on corroding biofilm in a model drinking water system following intentional contamination.
【24h】

Persistence of microbiological agents on corroding biofilm in a model drinking water system following intentional contamination.

机译：故意污染后，微生物制剂对模型饮用水系统中腐蚀生物膜的持久性。

获取原文
获取原文并翻译 | 示例
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Persistence of vegetative and spore forming bacteria on corroded iron surfaces in drinking water was studied using biofilm annular reactors operated under oligotrophic conditions. Reactors were inoculated with either Klebsiella pneumoniae or Bacillus globigii in spore form, and persistence was monitored in the bulk and biofilm phases. In the first phase of experimentation using K. pneumoniae, an initial cell concentration of 106 MPN/ml in the bulk water phase resulted in significantly longer adhesion than initial concentrations one and two orders of magnitude lower. K. pneumoniae cultured in low nutrient growth medium persisted longer in dechlorinated tap water than those cultured in full strength medium. Cell surface charge was more negative under low nutrient conditions, and this influenced electrostatic attraction between the cells and the oxidized iron surface. Cells grown in full strength media persisted longer in water with both low (0.2 mg/L) and high (>0.5 mg/L) free chlorine residuals. Growth media injected with the cells dechlorinated the water allowing adhesion without inactivation. Microelectrode measurements showed a 40-70% drop in free chlorine from the bulk to the coupon surface, which decreased disinfectant potency against adhered cells. Growth and injection conditions clearly influenced cell adhesion and persistence, but permanent colonization of the corroded iron surface by K. pneumoniae was not observed.;The second phase of experimentation examined persistence of B. globigii (in spore form) on corroded iron. Spores were inoculated at 106 CFU/ml in the reactor bulk water, which was dechlorinated for the first experiment. Dechlorination allowed observation of the effect of shear and biofilm sloughing on persistence. Approximately 50% of the spores initially adhered were not detected after one month of operation. Addition of 10 mg/L of free chlorine after one month led to an immediate 2 log reduction, but B. globigii concentrations stabilized shortly thereafter. Increasing the chlorine concentration to 25 or 70 mg/L had no effect on inactivation. B. globigii was also injected in the presence of a normal chlorine residual (0.8 mg/L), which resulted in a steady reduction of B. globigii over one month, but density on the coupons stabilized at the same levels as the dechlorinated reactor after decontamination. Adding elevated chlorine levels after 1 month (10, 25 and 70 mg/L) had no effect on the coupon concentration. Starting decontamination immediately after injection still resulted in stabilization of the cell counts. This indicates that free chlorine cannot reach portions of the corroded iron surface where B. globigii spores are adhered. K. penumoniae presumably adhered to the same biofilm areas as the spores, but could not survive in the oligotrophic drinking water environment. As B. globigii spores are dormant and not respiring, they will persist indefinitely even in the presence of high levels of free chlorine when adhered to a tortuous surface like corroded iron.
机译：使用在贫营养条件下运行的生物膜环形反应器研究了饮用水中腐蚀的铁表面上营养细菌和芽孢形成细菌的持久性。用孢子形式的肺炎克雷伯氏菌或globigii芽孢杆菌接种反应器，并在本体相和生物膜相中监测持久性。在使用肺炎克雷伯菌的实验的第一阶段，本体水相中的初始细胞浓度为106 MPN / ml，导致粘附力明显比初始浓度低一个和两个数量级。在低营养生长培养基中培养的肺炎克雷伯菌在脱氯自来水中的持续时间比在全强度培养基中培养的肺炎克雷伯菌更长。在低营养条件下，细胞表面电荷更负，这影响了细胞与氧化铁表面之间的静电吸引。在全强度培养基中生长的细胞在水中的游离氯残留量较低（<0.2 mg / L）和较高（> 0.5 mg / L）的时间更长。注入细胞的生长培养基对水进行了脱氯处理，从而使附着力得以保持而不会失活。微电极测量显示从主体到试样表面的游离氯下降了40-70％，这降低了对粘附细胞的消毒效力。生长和注射条件明显影响细胞粘附和持久性，但是未观察到肺炎克雷伯菌对腐蚀的铁表面永久定植。实验的第二阶段检查了球形双歧杆菌（孢子形式）在腐蚀的铁上的持久性。将孢子以106 CFU / ml的浓度接种在反应器的大体积水中，该水在第一个实验中进行了脱氯处理。脱氯可以观察到剪切和生物膜脱落对持久性的影响。手术一个月后未检测到最初附着的约50％的孢子。一个月后添加10 mg / L的游离氯可立即减少2 log，但随后球果双歧杆菌的浓度稳定下来。将氯浓度增加到25或70 mg / L对灭活没有影响。在正常氯残留量（0.8 mg / L）存在的情况下，还注射了球果双歧杆菌，这导致球果双歧杆菌在一个月内稳定减少，但试样块上的密度稳定在与脱氯反应器相同的水平。去污。 1个月后（10、25和70 mg / L）添加较高的氯水平对试样浓度没有影响。注射后立即开始净化操作仍可导致细胞计数稳定。这表明游离氯不能到达铁锈菌孢子附着的腐蚀铁表面的一部分。推测肺炎克雷伯菌与孢子附着在相同的生物膜区域，但在贫营养饮用水环境中无法生存。由于球形双歧杆菌的孢子处于休眠状态且不呼吸，因此即使粘附在弯曲的表面（如腐蚀的铁）上，即使存在大量游离氯，它们也会无限期存在。

著录项

  • 作者

    Szabo, Jeffrey G.;

  • 作者单位

    University of Cincinnati.;

  • 授予单位 University of Cincinnati.;
  • 学科 Biology Microbiology.;Engineering Environmental.
  • 学位 Ph.D.
  • 年度 2006
  • 页码 156 p.
  • 总页数 156
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号