Inexpensive, Disposable Presence-Absence Test for Coliforms and Escherichia coli in Water

Area of Science:

• Environmental Microbiology
• Water Quality Analysis
• Microbial Detection Techniques

Background:

• Traditional water quality testing methods can be cumbersome.
• There is a need for efficient and reliable methods for detecting indicator organisms like Escherichia coli.
• The use of chromogenic substrates can simplify microbial detection.

Purpose of the Study:

• To evaluate the efficacy of a novel Presence-Absence (P-A) test utilizing Whirl-Pak® bags for water quality analysis.
• To compare the performance of the bag P-A test with conventional P-A tests and the most-probable-number (MPN) method.
• To assess the reliability of 4-methylumbelliferyl-β-D-glucuronide (MUG) for Escherichia coli detection in the bag system.

Main Methods:

• Pasteurization of Whirl-Pak® bags containing dehydrated P-A Broth and MUG with gamma irradiation.
• Inoculation of bags with 100 ml of water samples.
• Incubation and observation for microbial growth and MUG hydrolysis.
• Comparison with P-A tests in glass and polysulfone bottles and a 5-tube Laury Tryptose Broth (LTB) MPN method.
• Analysis of 29 surface-water, 9 well-water, and 2 sewage effluent samples.

Main Results:

• The Whirl-Pak® bag P-A test demonstrated comparable results to traditional P-A tests and the MPN method.
• Chi-square analyses showed no significant differences (P≤0.1) among the tested methods.
• Hydrolysis of MUG provided excellent detection of Escherichia coli.
• MUG hydrolysis was easiest to determine within the Whirl-Pak® bags.

Conclusions:

• The pasteurized Whirl-Pak® bag P-A test is a reliable and effective method for water quality assessment.
• This method offers a convenient and efficient alternative for detecting Escherichia coli in various water types.
• The use of MUG in the bag system simplifies the detection and determination of Escherichia coli presence.