4. Bacteria
Bacteria are single-celled microorganisms that have been present on Earth for billions of years.
These microscopic organisms are found in almost every environment, from soil to water to air.
Bacteria are essential for human survival, as they play a role in the production of food, the
decomposition of organic matter, and the regulation of ecosystems.
Bacteria are classified according to their shapes and sizes, including cocci, bacilli, spirilla, and
vibrios. They can also be classified according to their metabolic processes, such as photosynthesis,
chemosynthesis, and respiration. Bacteria can cause food-borne illnesses, such as salmonellosis,
listeriosis, and botulism.
5. Fungi
Fungi are eukaryotic organisms that have been present on Earth for millions of
years. These microorganisms are found in almost every environment, from soil to
water to air. Fungi are essential for human survival, as they play a role in the
production of food, the decomposition of organic matter, and the regulation of
ecosystems.
Fungi are classified according to their shapes and sizes, including yeasts, molds,
and mushrooms. They can also be classified according to their metabolic
processes, such as photosynthesis, chemosynthesis, and respiration. Fungi can
cause food-borne illnesses, such as candidiasis, aspergillosis, and histoplasmosis.
6. Viruses
Viruses are non-living infectious agents that have been present on Earth for
millions of years. These microscopic organisms are found in almost every
environment, from soil to water to air. Viruses are essential for human survival, as
they play a role in the production of food, the decomposition of organic matter,
and the regulation of ecosystems.
Viruses are classified according to their shapes and sizes, including helical,
icosahedral, and complex. They can also be classified according to their metabolic
processes, such as photosynthesis, chemosynthesis, and respiration. Viruses can
cause food-borne illnesses, such as hepatitis A, norovirus, and rotavirus.
7. Protozoa
Protozoa are single-celled eukaryotes that have been present on Earth for millions
of years. These microscopic organisms are found in almost every environment,
from soil to water to air. Protozoa are essential for human survival, as they play a
role in the production of food, the decomposition of organic matter, and the
regulation of ecosystems.
Protozoa are classified according to their shapes and sizes, including amoebas,
flagellates, and ciliates. They can also be classified according to their metabolic
processes, such as photosynthesis, chemosynthesis, and respiration. Protozoa can
cause food-borne illnesses, such as giardiasis, cryptosporidiosis, and
trichomoniasis.
8. Algae
Algae are single-celled or multi-celled eukaryotes that have been present on Earth
for millions of years. These microscopic organisms are found in almost every
environment, from soil to water to air. Algae are essential for human survival, as
they play a role in the production of food, the decomposition of organic matter,
and the regulation of ecosystems.
Algae are classified according to their shapes and sizes, including diatoms,
dinoflagellates, and green algae. They can also be classified according to their
metabolic processes, such as photosynthesis, chemosynthesis, and respiration.
Algae can cause food-borne illnesses, such as ciguatera poisoning, paralytic
shellfish poisoning, and diarrhetic shellfish poisoning.
9. Yeasts
Yeasts are single-celled fungi that have been present on Earth for millions of years.
These microscopic organisms are found in almost every environment, from soil to
water to air. Yeasts are essential for human survival, as they play a role in the
production of food, the decomposition of organic matter, and the regulation of
ecosystems.
Yeasts are classified according to their shapes and sizes, including saccharomyces,
candida, and schizosaccharomyces. They can also be classified according to their
metabolic processes, such as photosynthesis, chemosynthesis, and respiration.
Yeasts can cause food-borne illnesses, such as candidiasis, histoplasmosis, and
cryptococcosis.
