Goel Sudha, Bouwer Edward J
Department of Geography and Environmental Engineering, The Johns Hopkins University, Baltimore, MD 21218, USA.
Water Res. 2004 Jan;38(2):301-8. doi: 10.1016/j.watres.2003.09.016.
Inactivation of Klebsiella pneumoniae cultures by chlorine and chloramine was evaluated under different growth conditions by varying nutrient media dilution, concentrations of essential inorganic nutrients (FeCl3, MgSO4, phosphate, and ammonium salts), and temperature. All inactivation assays were performed at room temperature (22-23 degrees C) and near neutral pH (7.2-7.5). CT(99.9) values for chlorine increased >20-fold and for chloramine increased 2.6-fold when cells were grown in 100-fold diluted nutrient broth (2NB) solutions (final TOC of 35-40 mg/L). Background levels of Mg: 6.75 x 10(-2) mM and Fe: 3.58 x 10(-5) mM or high levels of FeCl3 (0.01 mM) and MgSO4 (1 mM) during growth resulted in the highest resistances to chlorine with CT(99.9) values of 13.06 (+/-0.91) and 13.78 (+/-1.97) mg-min/L, respectively. Addition of low levels of FeCl3 (0.001 mM) and MgSO4 (0.1 mM) to K. pneumoniae cultures during growth resulted in the lowest bacterial resistances to inactivation; CT(99.9) values ranged from 0.28 (+/-0.06) to 1.88 (+/-0.53)mg-min/L in these cultures. Increase in growth temperature from 22.5 degrees C to 35 degrees C for unamended 2NB cultures resulted in a 42-fold decrease in CT(99.9) values for chlorine. A similar change in temperature resulted in no significant change in C*T(99.9) values for chloramine. These results indicate that inactivation of K. pneumoniae cultures by chlorine was highly sensitive to changes in growth conditions unlike inactivation by chloramine.
通过改变营养培养基稀释度、必需无机营养物（FeCl3、MgSO4、磷酸盐和铵盐）浓度以及温度，在不同生长条件下评估了氯和氯胺对肺炎克雷伯菌培养物的灭活效果。所有灭活试验均在室温（22-23摄氏度）和近中性pH值（7.2-7.5）下进行。当细胞在100倍稀释的营养肉汤（2NB）溶液（最终总有机碳为35-40mg/L）中生长时，氯的CT(99.9)值增加了20倍以上，氯胺的CT(99.9)值增加了2.6倍。生长过程中Mg的背景水平为6.75×10(-2) mM，Fe的背景水平为3.58×10(-5) mM，或高水平的FeCl3（0.01 mM）和MgSO4（1 mM）导致对氯的最高抗性，CT(99.9)值分别为13.06（±0.91）和13.78（±1.97）mg-min/L。在肺炎克雷伯菌培养物生长过程中添加低水平的FeCl3（0.001 mM）和MgSO4（0.1 mM）导致细菌对灭活的抗性最低；这些培养物中的CT(99.9)值范围为0.28（±0.06）至1.88（±0.53）mg-min/L。对于未添加营养物质的2NB培养物，生长温度从22.5摄氏度升高到35摄氏度导致氯的CT(99.9)值降低了42倍。类似的温度变化导致氯胺的CT(99.9)值没有显著变化。这些结果表明，与氯胺灭活相比，氯对肺炎克雷伯菌培养物的灭活对生长条件的变化高度敏感。
