Note: susceptibility to chlorine of Aeromonas hydrophila strains.
The susceptibility of five Aeromonas hydrophila strains and one Escherichia coli strain to chlorine was studied under carefully controlled laboratory conditions. Of the Aer. hydrophila strains, two were from untreated water, two from tap water (immediately downstream of a water treatment plant) and one from the DSM collection. The study included disinfectant concentration (0.1, 0.2 and 0.5 mg l-1), pH (6, 7 and 8) and temperature (4, 21 and 32 degrees C) as controlled variables. The results indicated that the untreated water strains, the DSM strain and the E. coli strain were inactivated within 1 min of chlorine treatment. The strains from chlorinated water (TW11 and TW27) showed a different susceptibility to chlorine disinfection, the rate of inactivation being greater at pH6 than at pH8 for both strains. Under the standard conditions of temperature 21 degrees C, pH7 and chlorine concentration 0.2 mg l-1, an increase or decrease of approximately 1 log unit in the number of bacteria did not affect the kill rate of the strains TW11 and TW27.
Istituto di Produzioni e Preparazioni Alimentari, Facoltà di Agraria, Foggia, Italy.
S
S
Massa
R
R
Armuzzi
M
M
Tosques
F
F
Canganella
L D
LD
Trovatelli
D016980:Aeromonas hydrophila / Q000187:drug effects* / Q000254:growth & development / Q000302:isolation & purification; D002713:Chlorine / Q000494:pharmacology*; D015169:Colony Count, Microbial; D004203:Disinfection; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli / Q000187:drug effects / Q000302:isolation & purification; D006863:Hydrogen-Ion Concentration; D013696:Temperature; D014871:Water Microbiology; D014881:Water Supply
D002713:Chlorine