Having a pure culture of bacteria when performing biochemical tests is essential in order to identify the metabolic capabilities of the organism accurately. This statement is due to the fact that mixed cultures of bacteria can mask the metabolic capabilities of individual species, making it challenging to identify biochemical activities precisely. As an example, the study conducted by Riva et al. (2022) found that a group of culturable bacterial genera were present regardless of the growth conditions utilized for the bacterial isolation. Hence, the presence of other organisms in the culture can interfere with the metabolic capabilities of the organism, making it impossible to obtain reliable and exact results from the biochemical tests (Riva et al., 2022). Therefore, it is imperative for researchers to use pure cultures of bacteria when performing biochemical tests in order to determine the metabolic capacities of the organisms accurately.
An extremely efficient technique to identify an organism quickly and accurately is to cultivate it on a variety of media. This phenomenon happens because, depending on the micronutrients and physical conditions in the media, the many cultures employed to cultivate the organism will choose different bacterial species. For example, a study conducted by Aguilar et al. (2019) found that the addition of different carbon sources to the culture media resulted in the growth of different bacterial species. Thus, this paper stressed how various media can favour particular bacterial species and how employing a variety of media can help researchers quickly discover an assortment of bacterial species.
The environmental conditions that an organism is best suited to live can be determined by cultivating the organism on a variety of media. This phenomenon happens because the media’s physical and chemical conditions can help determine the optimal environmental conditions for the organism, such as the optimal temperature and pH (Bonnet et al., 2020). Therefore, the researcher can quickly identify the organism as well as its optimal environmental conditions in a short period of time by using several media.
The technique used to isolate pure cultures from a specimen that contains mixed flora is known as the streak plate method. This technique involves taking a sample of the specimen and placing it on the surface of an agar plate (Ahern, 2018). The sample is then streaked across the agar plate in a zig-zag motion, which allows for the separation of individual bacterial colonies. After the initial streaking, the plate is incubated at the optimal temperature and humidity for the specific species. After incubation, the bacterial colonies can be observed on the agar plate. The researcher can then use a loop or a pipette to pick the individual colonies and transfer them to a new agar plate for further culturing (Ahern, 2018). This technique allows for isolating the pure bacterial cultures, as the individual colonies are no longer surrounded by the mixed flora.
The streak plate method is a widely used approach, as it is relatively simple and inexpensive. Additionally, it is also a highly effective method, as it allows for the isolation of pure cultures in a relatively short period of time (Ahern, 2018). The technique is also highly versatile, as it can be used to isolate a variety of bacterial species from a mixed flora sample. Furthermore, the technique can also be used to isolate bacterial species from both liquid and solid samples. Thus, the streak plate method is widely used for isolating pure bacterial cultures from mixed flora samples.
The characteristics used to distinguish bacterial colonies may differ depending on the species and the type of media used. However, some of the most common methods used to distinguish bacterial colonies include size, shape, color, elevation, and opacity. Size is essential in distinguishing colonies, as colonies can be from several millimetres to a centimetre in size (Green & Goldman, 2021). The shape of the colony is also essential for identification, as colonies can be round, oval, or irregular (Green & Goldman, 2021). Color can also be used to distinguish bacterial colonies, as colonies may range from pink to yellow to brown and even black in some instances.
Additionally, the texture of the colony can be used to distinguish it. Some colonies may be rough, while others may be smooth or mucoid (Green & Goldman, 2021). Furthermore, the elevation of the colony is also considered in distinguishing colonies. Bacterial colonies can be flat or raised, depending on the species, and may also have edges that are raised or depressed (Green & Goldman, 2021). Last but not least, the opacity of the colony may also be used to distinguish it. Some colonies may be translucent, while others may be opaque or cloudy (Green & Goldman, 2021). With all of these characteristics in mind, it is possible to distinguish bacterial colonies from one another.
In conclusion, cultivating an organism on various mediums is an incredibly efficient technique to identify the organism quickly. It can also aid in determining the environmental circumstances in which the organism is most adapted. The streak plate method, which is popular and affordable, is a method for isolating pure bacterial cultures from samples of mixed flora. You can identify bacterial colonies using size, shape, color, elevation, opacity, and texture traits. Consequently, it is feasible to precisely determine an organism’s metabolic capacities in a concise amount of time.
References
Aguilar, P., Dorador, C., Vila, I., & Sommaruga, R. (2019). Bacterial communities associated with spherical nostoc macrocolonies. Frontiers in Microbiology, 10. Web.
Ahern, H. (2018). Microbiology: A laboratory experience (Illustrated). State University of New York OER Services.
Bonnet, M., Lagier, J., Raoult, D., & Khelaifia, S. (2020). Bacterial culture through selective and non-selective conditions: the evolution of culture media in clinical microbiology. New Microbes and New Infections, 34, 100622. Web.
Green, L. H., & Goldman, E. (2021). Practical handbook of microbiology (4th ed.). CRC Press.
Riva, V., Mapelli, F., Bagnasco, A., Mengoni, A., & Borin, S. (2022). A Meta-Analysis Approach to Defining the Culturable Core of Plant Endophytic Bacterial Communities. Applied and Environmental Microbiology, 88.