Water sampling paper

Finding Total Coliforms and Enterococcus in Water Samples from Cidra in the River Arroyata

Alejandra González and Angeline Figueroa

RISE

AbstractWaters in the world are contaminated by different pathogens. In Puerto Rico,

the waters contain coliforms which are a type of bacteria and they are divided into two groups, total coliforms and fecal coliforms. Enterococcus is another type of bacteria that affect our waters and they can be a hazard for the health of people and animals. For this project we wanted to know if there was presence of total coliforms and enterococcus in the waters of the river Arroyata in Cidra, Puerto Rico. Since fecal coliforms are endemic in the waters of Puerto Rico they were going to be present in the samples taken from the river, unless the samples were treated against fecal coliforms.

IntroductionColiforms are broad class of bacteria found in our environment, including the

feces of man and other warm-blooded animals. The presence of coliform bacteria in drinking water may indicate a possible presence of harmful, disease-causing organisms. There are two types of Coliforms, fecal and total. Total coliforms are bacteria that are found in the intestines of animals and in the environment, while fecal coliforms are found only in the intestines of animals and these are endemic in the waters of Puerto Rico and they are used to know the presence of pathogenic organisms. Enterococcus is a genus of lactic acid bacteria, which are the ones that are used for example in yogurt. Two species are common commensal organisms in the intestines of humans: E. faecalis and E. faecium, some infections caused by Enterococcus include urinary tract infections, bacteremia, bacterial endocarditis, diverticulitis, and meningitis. Our question for this project was if we were going to be able to find total coliforms and enterococcus in the waters of the river Arroyata in Cidra. The hypothesis to this question would be that yes, we are going to be able to find coliforms and enterococcus in the mentioned river. Since fecal coliforms are endemic in the waters of Puerto Rico we are sure that they will show in our results.

Materials and MethodsThe samples were collected on May 3, 2013 from the River Arroyata in Cidra,

Puerto Rico. We collected six samples of one hundred milliliters, two for each section of the river. The first four samples were collected near the town and the last two a bit far from the town. Before each collection we measured the temperature

and conductivity with a multimeter and the turbidity utilizing a turbidmeter. In addition, there was used a GPS to identify the latitude and longitude from were the sample were collected, the sample number to identify each sample with its place of collection and to record the time of the collection. The samples were identified as follow: the first two, from the first section of the river, were numbered 66, the third and forth from the second section, were 69 and the last two from the third section, were 70.

After the collection we brought the samples to the laboratory to prepare them for the analysis process. The samples were divided into two groups of three. For the first three, we poured Colilert substrate and the Enterolert substrate was added to the other group of three samples. The Colilert is to identify fecal and total coliforms and the Enterolert to identify enterococcus bacteria. These substrates are detectors that have nutrients indicator that will be metabolized by the bacteria resulting in a change in color in the water sample if result positive to the bacteria mentioned before. For instance, if the test resulted positive for total coliforms the water will change from clear to yellow. And, if the same sample is put under ultraviolet light the ones that change from yellow to light violet resulted positive for fecal coliforms. For the enterococcus test, the water will change from green to blue if resulted positive for that bacteria. The next step was to pour each water samples with substrates in six quantity trays (one for each sample) and then seal them with the quantity tray sealer. After that, the samples were incubated for twenty-four hours, the one with Colilert at 35-Celsius degrees and the one with Enterolert at 41-Celsius degrees.

The next day we took out the quantity trays from the incubator to analyze them. For the total coliform test, we observed how much water in the quantity trays were changed to yellow, for the fecal coliforms we put the under ultraviolet light and see the amount of water that changed to light violet and for the enterococcus we observe how much water changed to blue.

ResultsIt was difficult to have an accurate number of bacteria in one hundred

milliliters of water due to the method utilized, so the results are the most probable number (MNP) of bacteria that one hundred milliliters of water could contain.

For the test of the total coliforms the three samples (66, 69 and 70) resulted in the same amount of that bacteria 2,419.6MNP. The fecal coliforms test resulted in a different amount: the 66 samples had 307.8MNP, the 69, 172.6 and the 70, 210.5. Finally, for the enterococcus test resulted in diverse number of bacteria too: the 66 samples 344.8, the 69 had 579.4 and the 70 had 156.5

*-Conductivity is a way to measure ions dissolved in a water body. As low the conductivity is fresher is the water. Conductivity should range from 150 to 500 micromhos per centimeter (mhos/cm) to consider the water as pure.

*-Turbidity is measured at nephelometric turbidity units (NTU) and we can see turbidity in the color of the water.

Conclusion

Based on the results we could deduce that the conductivity was slightly higher than the normal ranges, which are 150 to 500 mhos/cm. This indicates that the water is not too pure for its use. Considering that there are many factors that altered the conductivity, such as temperature, these results can vary making the water to be in the ranges of fresh water. Also, that the turbidity resulted with an NTU lower than the range, which is 10NTU. This quantity of turbidity indicates that the water is plenty pure, because it does not have too much organic and inorganic material. We were able to obtain positive results in the six samples. In other words, we did find fecal and total coliforms and enterococcus bacteria in the water of the river Arroyata in Cidra, Puerto Rico.

Consequently, we were able to measure the water quality of three different section of the river, so we can conclude that as far as we moved to collect the samples from the town was less bacteria. With all the gathered information we will be able to orient people on how to drink purified water and the dangers of ingesting water that has not been treated against pathogens, campaigns can be also an option to tell more people to help keep our waters cleaned.

Literature Cited

http://www.bfhd.wa.gov/info/coliform.php (Public Health of US)

http://www.gobierno.pr/NR/rdonlyres/BA0D6158-5A70-449A-B385-D55F654720A8/0/EstandaresCalidadAgua.pdf (Junta de Calidad de Ambiental de Puerto Rico)