Bacteria are fascinating microorganisms that can be found almost everywhere on Earth.
Despite their tiny size, they play a crucial role in various ecological processes and are essential for the sustenance of life on our planet.
One of the most intriguing aspects of bacteria is their ability to synthesize their own food.
This ability, known as autotrophy, allows certain bacteria to survive in environments where other organisms cannot. We will explore the concept of bacterial autotrophy and investigate how bacteria are capable of making their own food.
Can bacteria make their own food?
Not all bacteria are capable of making their own food. These bacteria do not have the ability to undergo photosynthesis or create their own energy through the conversion of sunlight into food.
But some bacteria called autotrophs can make their own food. These bacteria use an entirely different process to generate energy.
They do so by synthesizing organic compounds from simple inorganic substances such as carbon dioxide, water, and nitrogen.
Autotrophic bacteria are found in various environments such as soil, water, and the human body.
These bacteria play a crucial role in various biogeochemical cycles and are important for the balance of the ecosystem.
There are two types of autotrophic bacteria and they are classified based on their energy source and the pathway they use to fix carbon dioxide.
- Photoautotrophs
- Chemolithotrophs
1. Photoautotrophs
Examples of photoautotrophic bacteria include Cyanobacteria and some purple and green bacteria.
These bacteria use light energy as their energy source and perform photosynthesis to fix carbon dioxide.
Autotrophic bacteria are important for the ecosystem because they play an important role in nutrient cycling.
They are able to synthesize their own organic compounds from inorganic sources, such as carbon dioxide and nitrogen, through processes such as photosynthesis and chemosynthesis.
This means they can serve as a primary producer in many ecosystems, which forms the basis of the food chain.
Apart from their importance in the ecosystem, autotrophic bacteria have various industrial applications as well.
One such application is the treatment of wastewater. Some autotrophic bacteria are used in a process called biological nitrogen and phosphorus removal, which removes nitrogen and phosphorus from wastewater.
This process is important to prevent eutrophication, a process in which an excess of nutrients in the water leads to an overgrowth of algae and other aquatic plants, which can deplete oxygen levels and harm aquatic life.
In addition, autotrophic bacteria are also used in the production of various food and beverages.
For example, lactic acid bacteria, which are autotrophic, are used in the production of yogurt, cheese, and other dairy products.
Similarly, some bacteria are used in the production of beer, wine, and other alcoholic beverages.
2. Chemolithotrophs
Chemolithotrophs on the other hand use inorganic compounds such as hydrogen, sulfur, or iron as their energy source and fix carbon dioxide through various metabolic pathways.
Examples of chemolithotrophs include Nitrosomonas and Nitrobacter which are involved in the nitrogen cycle in the soil and some thermophilic bacteria which are found in hot springs and geysers.
Chemolithotrophs are divided into two classes based on the electron donor used to generate energy: hydrogenotrophic and sulfur-oxidizing bacteria.
Hydrogenotrophs are chemolithotrophs that oxidize hydrogen gas to produce energy, whereas sulfur-oxidizing bacteria employ various sulfur compounds as electron donors to make energy, including elemental sulfur, thiosulfate, and sulfide.
Chemolithotrophs play a vital role in biogeochemical cycles by cycling key elements such as sulfur, nitrogen, and iron.
Sulfur-oxidizing bacteria, for example, play an important role in the sulfur cycle by oxidizing sulfur compounds to sulfate, which can then be used by other organisms.
Similarly, some chemolithotrophs, such as Nitrosomonas and Nitrobacter, contribute to the nitrogen cycle by converting ammonia to nitrite and nitrite to nitrate.
In addition to their ecological importance, chemolithotrophs have various industrial and biotechnological applications.
For example, some sulfur-oxidizing bacteria are used in the biodesulfurization of fossil fuels to remove sulfur impurities, which can cause environmental problems.
Additionally, some hydrogenotrophic bacteria such as Hydrogenovibrio are used in biofuel production by utilizing hydrogen gas as an energy source.
Why can’t bacteria make their own food?
It is critical to note that not all bacteria are unable to produce their own food.
Many autotrophic bacteria, in fact, are capable of making their own food through photosynthesis or chemosynthesis.
However, many bacteria are heterotrophic, which means they cannot manufacture their own food and must rely on organic substances from outside sources for energy and sustenance.
Saprophytic bacteria and parasitic bacteria are the two types of heterotrophic bacteria.
Saprophytic bacteria get their energy and nutrients from decomposing organic things like plants and animals.
They use enzymes to break down these organic substances and absorb the nutrients that arise. Saprophytic bacteria include decomposers such as Bacillus and Pseudomonas.
Parasitic bacteria, on the other hand, live on or within other species and obtain their energy and nutrition from their host.
They may injure or infect the host organism. Bacteria that cause tuberculosis, strep throat, and pneumonia are examples of parasitic bacteria.