Effect of chlorination on beta-D-galactosidase activity of sewage bacteria and Escherichia coli.
The effect of chlorine on beta-D-galactosidase activity of sewage bacteria and Escherichia coli was studied. beta-D-galactosidase activity of sewage was more resistant to chlorine than faecal coliform cultivability. At low initial dosage (0.05 mg Cl2 l-1) neither cultivability (colony-forming units (cfu)), nor enzyme activity of E. coli suspensions were severely impaired. When initial chlorine concentration was increased to 0.1 mg Cl2 l-1, the cfu number decreased whereas enzyme activity remained high, i.e. the enzyme activity calculated cfu-1 increased. At higher chlorine doses both cfu and enzyme activity were reduced, but non-cultivable cells retained assayable activity after chlorination. Mean values of the enzyme activity calculated cfu-1 decreased when the chlorine dosage was increased from 0.1 to 0.5 mg Cl2 l-1, but were not significantly different (P > 0.05) for dosages of 0.2-0.7 mg Cl2 l-1. After chlorination, beta-D-galactosidase activity of E. coli was less reduced than cfu and direct viable count numbers, but more reduced than 5-cyano-2-3, ditolyl tetrazolium chloride and total cell counts, and the enzyme activity represented an alternative activity parameter of chlorinated samples.
Tryland
I
I
Department of Hydraulic and Environmental Engineering, Norwegian University of Science and Technology, Trondheim, Norway.
Pommepuy
M
M
Fiksdal
L
L
D001426:Bacterial Proteins / Q000187:drug effects* / Q000378:metabolism; D002713:Chlorine / Q000494:pharmacology*; D015169:Colony Count, Microbial; D004926:Escherichia coli / Q000187:drug effects* / Q000201:enzymology / Q000254:growth & development; D005697:Galactosides / Q000378:metabolism*; D018384:Oxidative Stress; D012722:Sewage / Q000382:microbiology*; D013696:Temperature; D013997:Time Factors; D014871:Water Microbiology
D001426:Bacterial Proteins; D005697:Galactosides; D012722:Sewage; C007816:beta-galactoside; D002713:Chlorine