It is often necessary to identify one strain among the various strains of a species. For instance, there is a need to identify a particular pathogenic strain so that the source of an outbreak can be easily determined. In this case, one may want or wish to determine whether a strain is of Legionella pneumonia, which may be isolated from an air conditioning system in the train as to that isolated from a patient with Legionnaire's disease. For example, in an ecological study, one might be attentive whether a particular strain is Bacillus spherical that may be isolated from soil samples.
One may decide to use traditional methods; others are DNA fingerprinting methods based on the techniques of molecular biology. DNA fingerprinting is the most explicit way available to identify individual strains of species (Brenner, and James 37). In regard to this paper, the methods of gram morphology test, the gram positive bacteria test, and finally, gram negative bacteria test will be conducted. In such a way, the genus and species of the unknown bacteria will be determined.
While conducting the gram morphology test, it is necessary to keep the temperature persistent as it may differ depending on the size of the inoculum, incubation temperature, length of the incubation period, configuration of the medium, the surface to volume ration of the medium, and the principles used to define a positive and negative reaction.
Therefore, the results and characterization that are conducted at one laboratory may differ from those conducted at other laboratories, due to the difference in the environmental conditions created. This is done depending on the instruction. For instance, if one needs to have almost the same result to another. He or she may specify the physical condition under which the test could be carried out). This implies that the blind acceptance of characterization may lead to errors; therefore, in most cases, these conditions are not always specified as instructions.
Hence, it is advisable to include strains whose identity has been firmly established. For the comparative purposes when making use of the identification scheme, one have to be sure that the scheme is valid for the circumstances employed in one's laboratory (Brenner, and James 35).
However, the gram morphology reaction on an organism does depend on the presence of endospores. It is difficult to determine the strain if there are only a few spores in it. Otherwise, one may use heat resistance tests, acid production from sugar that may be difficult to distinguish from no acid production. If only small amounts of acid are produced, and a weak growth response may not be clearly distinguishable from "no growth".
Therefore, a precise definition of what constitutes a positive and negative reaction is often crucial in order for an exam to be useful for an identification scheme. Quite often, it is necessary to establish a sequence of tests used in identifying an isolate. It is crucial to determine the most general features first. For instance, it is essential to begin with determining whether it is a melibiose fermented, gelatin is liquefied, and the nitrate is reduced. Instead, it is important to begin with more general features, such as Gram staining reaction, morphology, and general sympathetic of metabolism. Therefore, it is necessary to establish whether the new isolate is a chemolithotrophic autotroph, a photosynthetic organism, or a chemoheterotroph organism. A living organism should be examined by the phase contrast microscopy and gram stained cells by light microscopy; other stains can be applied if it seems appropriate.
Nevertheless, taking into account morphology property, such as endospore production, holdfasts, sheaths, acid-fastness, cysts, stalks, fruiting bodies, budding division, or true branching, it is obvious that additional efforts in identification will be required. This will not depend on whether the organism is motile, and the category of motility (swimming, gliding) may be extremely useful in restricting the range of possibilities.
In some other cases, the source of the isolate can help to narrow down some possibilities. For instance, a spirillum isolated from the coastline sea water is likely to be an oceanosprillum species or gram positive cocci happening in the grape like clusters and remote from the human nasopharynx are likely to belong to the staphylococcus genus.However, the following summary is ever used in the mechanism of identification.
- Make sure that he/she has a pure culture.
- Work from broader categories down to smaller, specific categories of an organism.
- Use all instructions and information available for the range of possibilities.
- Application of common sense, i.e. it is necessary to use one's common sense at each and every stage.
- Use the minimum number of a test to make the identification.
Compare your isolated to that type or reference strains of the pertinent taxon to make sure the identification scheme used is certainly valid for the condition in your precise laboratory (Brenner, and James 35).
For instance, in the laboratory test done, I used the gram morphology test and brought the outcome to be gram rod. In addition, as the method discourages a conclusion to be drawn; the gram positive tests were used. As the conclusion was not valid enough, I decided to continue the process negative gram bacteria. In such a way, I was able to conclude the genus and species of bacteria. As a result, I was able to define the bacteria to be Yersinia pestis. It was possible due to the instructions given that the temperature was to be kept constant at 37C.
Nevertheless, bacteria that produce pigmented colonies are easy to recognize; though, they can cause difficulties in the bio-chemical tests. For instance, oxidase does involve a color reaction. In such cases, no pigmented variants are produced and used instead.
On the other hand, organism media have been devised to encourage a pigment production, and Mannitol Yeast Extract Agar is especially useful for Janthionobacterium and chomobactrium species. In addition, the temperature of the incubation should be maintained at 20-25C (Cowan, Steel, and Feltham 109). In the positive gram tests, the Pseudopodia react by oxidizing sugar. The following was not observed when the experiment was conducted (there was no positive result; hence, we proceeded to negative gram test). On the other hand, bacteria, such as gram negative rods, which are non-motile, do usually catalyze positively. The following test determines the species and genus of the bacteria (Cowan, Steel, and Feltham 109). It turns out that the genus and species were Yersinia pestis respectively; this was easily identified by the use of the manual.
In conclusion, identification of a bacteria strain is an extremely essential part in the laboratory; this will help in determining the cure or solving a declared outbreak. One can easily determine the genus and species of the given bacteria provided one does not rush to conclusions. It should be done in procedures, as such performing morphology test, doing the positive and negative test of gram. Using the manual, one can now easily determine the genus and species of unknown bacteria.
However, it does become easy to determine the species and genus of bacteria based on the origin, i.e. the habitat, if it was from the ocean or soil samples. Therefore, before one conducts the tests, it is necessary to establish where the bacteria have been withdrawn.