the direct cell count and the total heterotrophic plate count

the direct cell count and the total heterotrophic plate count

1. (a) The two methods, which are the direct cell count and the total heterotrophic plate count, provides the measure of all the bacteria present. However, these two methods do not yield a similar result. By comparison the method that yielded the higher count as per the results from the experiment is the direct cell count. This method involves counting colonies on a streak plate. Direct cell count method involved the microscopic counts using a hemocytometer or a counting chamber whereby the colonies could then be counted based on the identified volume of the culture that was spread on the plate; and then the bacteria concentration calculated. It is of the essence to note that different styles of counting chamber have dissimilar sized graduations. Whenever counting chamber s used it is fundamental to know the dimension of the graduations as well as the depth of the chamber. That will help to determine the volume of water in every chamber and as a result this volume can be used to convert to number of cells/ml correctly.
2. The results are as I would expect given that I expected the two methods to yield to yield different results. After the experiment, the results indicated that the direct cell count submitted a higher yield compared to the total heterotrophic plate count. The benefit of using the direct cell count is that it is just a rapid, easy and simple method that requires minimum equipment. Morphology of the bacteria present in the water could be observed as they count, unlike with the total heterotrophic plate count. Also, the results are as I would expect because the direct cell count has the capability of counting all bacteria in very dense suspensions, given that they were diluted appropriately. The key reason for obtaining a higher yield with the direct cell count was that it was a detailed method for more precisely counting the number of bacteria present and calculating the concentration of the entire sample.
3. (a) what is an indicator organism is simply a microorganism whose presence in the water sample signifies a possible existence of pathogens. Customarily, the fecal coliform group can be used as an indicator of the bacterial pathogen that is present and general wastewater contamination. Therefore, indicator organisms are used for assessing overall environment or sanitation conditions that may indicate or signal the potential presence of pathogens in the water safety concern for the consumers. It is imperative to be aware that indicator species are not essentially pathogenic. For instance, E. coli is a constituent of the faecal coliform group and, which is a more specific indicator of feacal pollution compared to the other forms of faecal caloriforms. For that reason, we use indicators in assessing water safety because they emerge to provide the best bacterial indication of bacterial contamination in water. The indicator organisms during experiment are bacteria for instance E. coli, nonspecific coliforms and P. aeruginosa. Indicator organisms are normally found in the human or animal gut and which, if detected, may suggest the presence of dirt in water and thus not safe for consumption or to be used for agricultural activities. Indicator organisms might become sub-lethally dented in surface waters as a result of various aspects expressed. Indicator bacteria are able to increase to form perceptible colonies on discerning agars in the choice of standard methodologies that are used to enumerate bacteria existence and indicator organisms. In the view that several of these organisms may perhaps maintain their pathogenicity, indicator organisms are used to comprehend the enumeration and estimating the risk to safety of a water sample.

(b). A coliform is a bacteria that is at all times present in the digestive tracts of human beings and animals, which is mostly found in their wastes. However, this bacterium can be also found in soil and plant material. In description, the califorms bacteria are rod shaped gram negative non spore that forms motile and non-motile bacteria. For that reason this bacteria can be used as an indicator organism for assessing water safety. The califorms bacteria are well thought-out as not harmful, though the coliform bacteria in drinking water can be a sign of a probable incidence of detrimental, disease causing pathogens. On the other hand, the thermotolerant coliforms also referred to as the faecal coliforms, are constantly present in elevated numbers in animal and human faeces. The thermotolerant coliform is the better indicator for faecal contamination. For example the E. coli is the most frequent thermotolerant coliform in animal and human wastes, characteristically 90% and therefore is considered as the most explicit indicator organism for recent faecal pollution in water.

3. Taking into account the future plans for treating for treating the water prior to use, the methods that I would suggest my lab uses to test the Alice’s irrigation water are the direct plate count method along with the membrane filtration method. The membrane filtration technique uses mEndo Agar whereas the direct plate count method uses VRBA Agar. For these two methods, the bacteria presence in the water can be identified prior to use, by the use of traits which are important indicating the presence of bacteria. The traits that are considered worthy are such as combinations of cell size and shape, gram stain reaction, special structures such as granules, endospores and acid-fast reaction. The method of membrane filter is an effective and acknowledged for testing water samples for bacterial contamination. This method involves less preparation compared to other traditional methods that are more involving in terms of arrangements. The membrane filter method is indeed one of the few methods that can allow the enumeration and the isolation of the bacteria present in the water sample. The Membrane filtration engrosses the utilization of membrane knowledge to separate the biomolecules and the concentration of bacteria elements in water. In this case, microfiltration can be for the parting of particles with 0.02 to 10 μm diameter. For water treatment, membrane filtration has become increasingly common method of testing bacterial presence in water.

Conversely, the direct plate count method uses the violet red bile agar and involves counting the colonies. In this case, an example of the counting colonies on a streak plate for the direct plate method includes the microscopic counts using the hemocytometer or using a counting chamber. The hemocytometer works by principally through creating a grid of volumetric separated into differently sized cubes for precise counting process. This process includes enumeration and phase growth, which engrosses both bacterial and phage application to the surface of an agar slab. The colonies are counted based on the known volume of the culture which is spread on the plate, and then the concentration of the cell calculated. Ultimately, these two methods of testing bacteria in water are easy, effective, and larger samples can also be incorporated.

4. Despite that I have used traditional enumeration methods is this analysis to determine the presence of indicator organism; I think that approaches of molecular biology such as the polymerase chain reaction could play an essential role in determining the microbiological quality of water. The polymerase chain reaction is a molecular biology approach that is widely used to rapidly make many copies of a particular DNA sample, a phenomenon that would have played a critical role in determining the microbiological quality of water. This approach could have facilitated the obtaining of very small sample of DNA and magnifying the sample large enough amounts hence aiding in determining the microbiological quality of water. The polymerase reaction method is simple although very constructive given that it bears the property of amplifying a segment of DNA interest and produces a lot of copies, which helps in determining the microbiological quality of water. By the use of PCR, one is able to easily determine the structure, the composition as well as the interactions of the cellular molecules that carry out the biological processes that are necessary for the cells maintenance and functions. The polymerase chain reaction is essentially a laboratory procedure that is capable of making multiple duplicates of the same piece of sample and it is carried out in a test tube where the sample is mixed with a polymerase chain reaction buffer solution that sustains optimal conditions for the whole process. With the PCR approach, there are three simple steps that are required for the synthesis reaction, which are important in determining the microbiological quality of water. The denaturing of the template into single strands, the annealing of primers to each initial strand for new strand synthesis and the extension of new strands from the primers are basic steps that can be used to precisely determine the microbiological quality of water.