Comparison of verification procedures for the membrane filter total coliform technique

Area of Science:

• Environmental Microbiology
• Water Quality Analysis
• Bacteriology

Background:

• Traditional methods for verifying total coliforms in drinking water rely on gas production in lauryl tryptose broth.
• This method can be less efficient and may not always accurately represent typical coliform genera.
• Improved verification techniques are crucial for ensuring public health and drinking water safety.

Purpose of the Study:

• To evaluate the efficacy of using enzyme activity tests (beta-galactosidase and cytochrome oxidase) for verifying membrane filter total coliform colonies.
• To compare the performance of enzyme-based verification with the conventional gas production method.
• To determine the accuracy of enzyme-based methods in identifying typical coliform genera.

Main Methods:

• Membrane filter technique was used for initial coliform detection in drinking water samples.
• Verification of presumptive coliform colonies was performed using tests for beta-galactosidase and cytochrome oxidase activity.
• Results were compared against verification based on gas production in lauryl tryptose broth.

Main Results:

• Verification of membrane filter total coliform colonies increased by 87% when using beta-galactosidase and cytochrome oxidase tests.
• Over 90% of coliforms verified by enzyme activity tests were representative of typical coliform genera.
• The enzyme-based method demonstrated superior performance compared to the gas production method.

Conclusions:

• Testing for beta-galactosidase and cytochrome oxidase offers a significantly more effective method for verifying total coliforms in drinking water.
• This approach enhances the accuracy of water quality assessments by better identifying relevant coliform bacteria.
• The findings support the adoption of enzyme-based tests for improved drinking water monitoring and public health protection.