Utilization of Hydrated Petrifilm Coupled with Filtration in the Detection and Enumeration of Escherichia coli in Water Samples
Angelou Vanessa Z. Tarroza1, Kristine V. Catsao2, Marie Angeli Ramos2,
Lucille C. Villegas1*, and Asuncion K. Raymundo1
1Microbiology Division, Institute of Biological Sciences, College of Arts and Sciences,
University of the Philippines Los Baños 4031 College, Laguna, Philippines
2Euro-med Laboratories Phil., Inc., Dasmariñas City, Cavite, Philippines
*Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.
ABSTRACT
Hydrated 3M™ Petrifilm™ E. coli / coliform (EC) plates coupled with filtration (HPECF) was found to be suitable in the analysis of 100 mL water samples, which is required in standard protocols in food and pharmaceutical industries. This was demonstrated with the use of suspensions of pure Escherichia coli and E. coli mixed with Enterobacter aerogenes and Pseudomonas aeruginosa – with 93–100% cell recovery. The results indicated that the HPECF method could be valuable in standard water quality analysis in pharmaceutical companies as it provides an acceptable and faster way to comply with the 2017 Philippine National Standards for Drinking Water (PNSDW). Likewise, HPECF results can be obtained after 48 h instead of 120 h as being currently used in the Most Probable Number (MPN) method, making HPECF three times faster than MPN. Furthermore, a simple cost-benefit analysis revealed that the use of HPECF can reduce the cost of water testing by 50% as compared to the MPN method. Consequently, the HPECF method is a more economical and faster alternative to the standard MPN method for water quality analysis for manufacturing companies.
INTRODUCTION
Water quality is of primary importance in a manufacturing company to ensure safe and good quality products. Likewise, from raw materials to end-product testing, the company should guarantee that appropriate tests and analyses are carefully and correctly done in order to ensure that their products meet the standards required by regulatory agencies. During water analysis, coliforms – primarily E. coli – are commonly detected and enumerated. Coliforms are gram-negative, aerobic to facultative anaerobes that are able to ferment lactose and produce gas at 35 °C within 48 h of incubation (Yousef and Carlstrom 2003). Fecal coliforms serve as a biological indicator of fecal contamination in water samples. Among the fecal coliforms, E. coli is the best indicator used in drinking water analysis because it is normally found in mammal’s gastrointestinal tract, and is known to survive the normal conditions of drinking water (Edberg et al. 2000). Moreover, the methods for its detection are relatively inexpensive compared to other coliforms. . . . . read more
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