Distribution of uidA gene sequences in Escherichia coli isolates in water sources and comparison with the expression of beta-glucuronidase activity in 4-methylumbelliferyl-beta-D-glucuronide media.
The uidA gene, which encodes the beta-glucuronidase enzyme, was detected in 97.7% of 435 Escherichia coli isolates from treated and raw water sources by DNA-DNA hybridization; 92.4% of the strains expressed the translational product in 4-methylumbelliferyl-beta-D-glucuronide-containing media after reinoculation. Upon initial isolation from water samples, the minimal medium o-nitrophenyl-beta-D-galactopyranoside-4-methylum-belliferyl -beta-D-glucuronide preparations failed to detect more than 50% of the E. coli isolates that possessed uidA gene. Treated water gave the lowest recovery, with Colilert producing 26% positive samples and Coliquik producing 48% positive samples. There appears to be no relationship between the intensity of the autoradiographic signals of the uidA gene and the expression of beta-glucuronidase activity. Therefore, another variable such as physiological condition of the bacteria could be responsible for the nonexpression of the enzyme activity.
Martins
M T
MT
Department of Microbiology, University of Sao Paulo, Brazil.
Rivera
I G
IG
Clark
D L
DL
Stewart
M H
MH
Wolfe
R L
RL
Olson
B H
BH
D001345:Autoradiography; D003470:Culture Media / Q000737:chemistry; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D005188:False Negative Reactions; D005966:Glucuronidase / Q000235:genetics / Q000378:metabolism*; D006923:Hymecromone / Q000031:analogs & derivatives*; D014871:Water Microbiology
D003470:Culture Media; D006923:Hymecromone; C034888:4-methylumbelliferyl glucuronide; D005966:Glucuronidase