The bacterial spores are capsules produced by bacteria. In such capsules, the cytoplasm and the genetic content of a cell are concentrated, which are wrapped in a series of protective layers.
These are extremely resistant to unfavorable external conditions, such as high and low temperatures, droughts, radiation, among others. They are also resistant to chemicals created by humans, such as antibiotics and disinfectants.
Bacillus anthracis spores, which causes anthrax disease.
In addition to this, the spores can be kept in an inactive state for many years, decades or even more. Once the spores detect improvements in environmental conditions, they will break free of their contents.
For this reason, they play an important role in the survival of the bacteria, since the fact that the spores can survive in such conditions makes it almost impossible to eliminate them.
Bacteria that produce spores often belong to genera sporolactobacillus , clostridium Y bacillus . Usually, these bacteria are found in the soil.
characteristics
- Spores can remain inactive for long periods of time.
- These structures are resistant to heat, pressure, radiation and strong acids and bases. In general, they are able to withstand extreme conditions that very few organisms can cope with.
- The spores are found is a state of semi-hydration. Only 10% of the water from the stem cell is passed to the spore during its formation.
- Due to this dehydration, spores can develop resistance to extreme temperatures and certain chemicals.
- Spores contain some proteins that have two main functions. The first is to protect deoxyribonucleic acid (DNA) from radiation, heat and other similar conditions. The second is to provide energy that may be useful for the spore.
- When the spore detects favorable changes in environmental conditions, it leaves its latent state. It takes the energy provided by the proteins and develops a cell. This process is known as germination.
Formation of bacterial spores
Environmental conditions are not always stable. For this reason, bacterial cells must resort to certain mechanisms.
When a bacteria senses changes in environmental conditions it has two options: adaptation or differentiation. If you choose to adapt, the bacteria will continue to live in the middle. In other words, it will continue to grow and cope with the conditions (at the risk of dying in the process).
If you choose differentiation, structures will be created that will aim to ensure the reproduction, survival or even dispersion of organisms. An example of this is the creation of capsules called spores.
Spores can remain dormant until external conditions improve. In case the bacterium decides to sporulate, it must go through a series of stages, which are presented below:
Step 0
The cell is in the growth stage.
Stage 1
There is an exchange of proteins inside the cell, so the DNA begins to become more abundant.
Stage 2
DNA is divided into two parts. One will remain inside the stem cell while the other will be destined for the spore. Each of these portions will be located at poles other than the cell.
At this stage the cytoplasmic membrane begins to produce a barrier, separating the stem cell from the spore.
Step 3
The cytoplasmic membrane closes completely around the spore.
Step 4
A protective layer, called cortical cortex, is formed. This layer is made up of proteins. In this stage, the exosporium is also constituted, which is the outermost layer of the spore.
This is one of the most important phases, as it is thanks to these layers that the spores acquire resistance to the various external conditions that could affect them.
Step 5
The cytoplasm is compacted and the elements are organized inside the spore, with which it matures.
Step 6
The spore is released to the outside.
Life time of spores
Studies of spore longevity indicate that spores may remain dormant for a decade, or even many more years.
The life span will vary according to the species of bacteria and the specific conditions that the spore must withstand.
For example, a study that was carried out with bacteria clostridium aceticum showed that even after three decades the spores of this microorganism were still alive.
Spores dating back to much older times have also been found. In 1995, Cano and Birocki performed a study with bacterial spores conserved in amber crystals.
The date of origin of these organisms was between 25 and 40 million years. Despite this, scientists were able to"resuscitate"them.
Another study found spores of halophilic bacteria conserved in salt crystals. These bacteria date back to 250 million years. In short, bacterial spores can survive for many years if kept in the right environment.
Bacterial genera and spores
The bacteria that usually form spores are those belonging to genera bacillus, clostridium and sporolactobacillus.
The gender bacillus form oval-shaped spores and are some of the most resistant. An example of this is the bacillus anthracis , responsible for the deadly anthrax disease.
For its part, the spores of the genus clostridium they differ from other bacteria because their shape is elongated (as if it were a bottle) and not oval. An example of bacteria of this genus is the clostridium tetani , which causes tetanus.
Finally, gender sporolactobacillus produces spores in rounded form.
Bacterial spores and the microbiology
Microbiology is the branch of biology that is responsible for the study of microscopic organisms, such as bacteria. This science analyzes the evolution and properties of microorganisms, detecting their function, their influence on terrestrial life and its usefulness.
The study of spores has been of importance for microbiology. Knowledge of these structures has made it possible to make advances in the area of sterilization, especially in medicine, agriculture and the food industry.
References
- Bacterial Endospore. Retrieved on September 28, 2017, from micro.cornell.edu
- Bacterial spore. Retrieved on September 28, 2017, from medical-dictionary.thefreedictionary.com
- Bacterial spore. Retrieved on September 28, 2017, from wikipedia.org
- Bacterial Spores: Current Research and Applications. Retrieved on September 28, 2017, from researchgate.net
- Bacterial Spores: Structure, Importance and examples of spores. Retrieved on September 28, 2017, from microbeonline.com
- Spore-forming bacteria. Recovered on September 28, 2017, from bode-science-center.com
- The composition and structure of bacterial spores. Retrieved on September 28, 2017, from biomedsearch.com
- Types of Spore Forming Bacteria. Retrieved on September 28, 2017, from sciencing.com