Abstract
In this essay, a description of a non-pathogenic and of a pathogenic microorganism is made. As microbiology aims the study of the microscopic organism that inhabit the ecosystems, the understanding of what are the species present in the biosphere, what are the condition in which they live, what are their metabolic processes and products, and of how can these influence, positively and/or negatively other living forms, including humans, it is essential to study them to know how their caused illnesses be prevented, treated and, furthermore, how can possibly help the health welfare. As examples, the Lactobacillus casei and Clostridium botulinum species of bacteria are described. Additionally, it is discussed how these bacteria, when properly known and understood, can be kept in control and even promote the development of several areas, like food processing and pharmaceutical ones.
Keywords:microbiology, non-pathogenic, pathogenic, Lactobacillus casei, Clostridium botulinum, characteristics, niches, health, metabolism, products, pathology.
Microbiology, as the study of microorganisms, their structure, niches where they can be found, environment factors that influence their existence and growth, functioning as a living organism and their relation type with other living organisms of our biosphere, has been a basic key to understand how these microscopic beings are present in almost every aspect of our daily lives and that they can also be the causers of multiple and serious illnesses, especially if proper care of our hygiene, place where we live and, most importantly, the food we ingest is not kept. Additionally, they have also been studied in terms of their metabolic products and of how these can be used in many different fields, from industrial production, to the pharmaceutical industry.
Non-Pathogenic Microorganism – Lactobacillus casei
The microorganism known as Lactobacillus casei makes part of the Bacteria group, being characterized as a rod-shaped, Gram-positive one, that can live facultatively in anaerobic environments, non-motile, not forming any spores, having a size range of 0.7-1.1 x 2.0-4.0 micrometer and being producers of lactic acid. It is also known as lactic acid bacteria.
Being such, they are, obviously, tolerant to acid; Lactobacillus casei cannot perform the synthesis of porphyrins and its metabolism is a strict fermentative one – where lactic acid has the role of main metabolic product. They produce such lactic acid from hexose sugars, using the Embden-Meyerhof pathway, and from pentoses through the 6-phosphogluconate/phosphoketolase pathway - Lactobacillus casei is a Group II species, meaning, facultatively heterofermentative.
Their growth temperature is of 15ºC, and Lactobacillus casei does not grow from 45ºC ahead. The growth also requires the following growth factors to occur: riboflavin, calcium pantothenate, folic acid and niacin. Their optimum pH level is 5.5.
This is a very adaptive species, which can be isolated from many different niches: dairy products (raw and fermented), plant products (fresh or fermented as well), and both intestinal and reproductive tracts of many animals, including humans. Being present in so many different environments, they can be applied in various areas, such as food industry, for milk fermentation or flavor intensification in some cheese varieties. Pharmaceutically, the lactic acid that Lactobacillus casei produces is also very important. This bacterial species can be used as a human probiotic, keeping the microbial flora of the gastrointestinal tract in good balance, and also by promoting health welfare, reducing the cholesterol levels, enhancing immune response, controlling the intestinal transit, preventing diarrhea, giving alleviation for lactose intolerant, preventing the development of other pathogenic bacteria species.
Pathogenic Microorganism – Clostridium botulinum
Clostridium botulinum is a bacteria species that is charaterized by being rod-shaped with a slight curve, Gram-positive, motile and living in anaerobic environments (i.e. they need low oxygen levels to live and to grow). This species forms heat-resistant spores, which have a hard coat that protects them and the essential parts of the bacterium, and is also involved in several layers of protection membranes; this way, it can stay dormant for large periods of time (years) until breaking the spore and developing. If the environment in which these bacteria find themselves is poor in the conditions they need, they will form the spores.
Clostridium botulinum lives and becomes activated (when in the form of spores) in environments with low acidity, i.e pH levels above 4.6, likes moisture and the temperatures this species prefers range from 3ºC to 43ºC. This species has a ubiquitous nature and its niches are in soil and water (especially in marine sediments), as bacteria or spores. It is also found in badly stored foods, both canned and fresh.
This is a pathogenic microorganism, responsible for a disease called botulism. It is not the bacteria or the spores that cause this illness, but the botulinum toxin that is produced. This toxin can be a protein neurotoxin, enterotoxin or haemotoxin. According to the different antigenic nature of the toxin, Clostridium botulinum is categorized in different types of strains: A, B, C, D, E, F and G. Botulism is caused in humans by the A, B, E and F types, in animals and birds by C and D and the G type has not been indentified yet as causing botulism.
Botulism is a serious, life-threatening disease, in which the ingestion of the botulinum toxin causes serious damage to the nervous system, the neural and nerve function, leading to a paralytic condition that can evolve to death.
Conclusion – Comparisons & Contrasts
Given the two microorganism species described above – Lactobacillus casei and Clostridium botulinum – which are non-pathogenic and pathogenic, respectively, one can find similarities in these bacteria, since they both are seen microscopically as having a rod-shaped, they are both Gram-positive and one can observe both in the same pH and temperature conditions, because both bacteria have values that are possible for both species to live and grow.
In contrast, however, these have also different traits when it comes to spore formation, which only Clostridium botulinum can do, and to the environment type, being that Lactobacillus casei is a facultative anaerobic microorganism and Clostridium botulinum is anaerobic. This is related to another characteristic that separates them: the niches where they are found: Lactobacillus casei is found in raw/fresh and fermented products (dairy and plant) and in the intestinal tract of many animals, including humans, being very adaptive in its evolution; Clostridium botulinum has its niches on soil and water (especially in marine sediments), and can also be found in badly stored canned or fresh foods.
Knowing these species’ characteristics, their presence and the results from their metabolic products action in other living beings can be controlled.
For example, knowing that Lactobacillus casei makes part of the intestinal flora and that it has the role of balancing this same flora, to maintain the good strains present and prevent the pathogenic ones to grow, the pharmaceutical industry could recreate their living and growing conditions, in order to produce probiotic medication. This probiotic medication, which is nothing else but these same bacteria, can then be prescribed and ingested, so that they can be present again in a intestinal tract that may have been modified by some previous illness, such as diarrhea, restoring the normal flora back again and, with it, the normal health and organism function. Other application of this bacteria species was the cheese production, knowing its ability to intensify and improve the taste of some varieties. Some countries (and their economy) are known for this same cheese variety.
Another example, now using Clostridium botulinum, of how the knowledge about the microorganisms and the understanding of how they live and function is essential is that, by knowing that this species is anaerobic and that it grows in a temperature range from 3ºC and 43ºC, one could learn the importance of keeping fresh foods and products refrigerated in order for Clostridium botulinum not to exist or if it does, be present only in spore form, which is harmless; on another hand, if the food is cooked in high temperature, the bacteria form can also be destroyed. Furthermore, knowing that such spores are heat-resistant, one could also learn that it would be necessary to cook the food and products in a pressure cooker for a certain period of time, in order to destroy both forms – bacteria and the spores. It is also known that the fatal toxin is also sensitive to temperature, so the cooking of the food and products will also destroy the toxin, keeping the food eatable (the cooking time must be bigger if oxygen levels are lower than normal, like in high altitude environments, since these bacteria grow and produce their metabolic toxin in low-oxygen levels).
References
DOE Joint Genome Institute (n.d). Lactobacillus casei ATCC 334. Retrieved from http://genome.jgi-psf.org/lacca/lacca.home.html
Schneider, Keith R., Chang, Alexandra, Goodrich, Renée M.. Preventing Foodborne Illness: Clostridium botulinum. Retrieved from http://edis.ifas.ul.edu/fs104
USDA Food Safety and Inspection Service. Fact Sheets: Foodborne Illness & Disease – Clostridium botulinum. Retrieved from http://fsis.usda.gov/Factsheets/Clostridium_botulinum/index.asp
Wong, Allison (n.d). Lactobacillus casei. Retrieved from http://microbewiki.kenyon.edu/index.php/Lactobacillus_casei
