Introduction of Microbiology
What is Microbiology?, Microbiology is an advanced biology course that studies unicellular (single cell), multicellular (cell colony), or acellular (lacking cells) microorganisms, including bacteria, archaea, algae, fungi, protozoa, and viruses.
The term biology is the combination of two important words such as bios, which means “living organisms”, and logy, which means “the study of”, So the complete meaning of Biology is the study of living organisms.
Whereas the term Micro refers to those tiny things or Very small things that are not visible with naked eyes, they need a microscope for clear visualization.
Therefore, microbiology is the study of very small living organisms called microorganisms or microbes. French chemist Louis Pasteur first used the term Microbiology.
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What Are Microbes or Microorganisms?
Microbes or microorganisms are microscopic organisms which may be unicellular or multicellular. Microorganisms are present everywhere, that is why they are called ubiquitous. The term “microbe” was first used by Sedillot.
There are present different types of Microbes such as viruses, bacteria, archaeans, certain algae, protozoa, and certain fungi. These are often referred to as “infectious agents” or “infectious particles,” rather than microorganisms.
There are present two types of microbes such as pathogenic microbes and nonpathogenic microbes. The disease-causing microbes are known as the pathogenic microbes and Nonpathogens refers to those microbes that do not cause disease.
About 3% of known microbes are capable of causing disease, and the vast majority of known microorganisms are nonpathogens. Among Nonpathogens, some are beneficial to us and some of them have no effects on us.
What are the types of Microorganisms?
There are present different types of Microorganisms that we will study under microbiology, such as; bacteria, archaea, fungi, protozoa, algae, and viruses.
Bacteria are a unicellular and prokaryotic cell which lack a nucleus. They appear in different shapes such as; bacillus (rod shape), coccus (spherical shape), spirilla (spiral shape), and vibrio (curved shape).
Bacteria are divided by using binary fission, they contain a peptidoglycan cell wall, they may contain flagella for motility. Based on the nature of cell wall bacteria are classified into two groups, such as
- Gram-Positive Bacteria.
- Gram-Negative Bacteria.
Based on their response to oxygen they are classified into three groups such as;
- Aerobic: They can survive in the presence of oxygen.
- Anaerobic: They can survive without oxygen.
- Facultative anaerobes: They can survive in both environments.
As compared to bacteria, archaea or archaebacteria are different in cell wall structure and they lack the peptidoglycans. They are prokaryotic in nature. They received their energy from hydrogen gas, carbon dioxide, sulfur, and sometimes sunlight.
They are classified into four groups, based on their habitat, such as;
- Methanogens: Produces methane.
- Halophiles: live in salt environments.
- Thermophiles: live in extreme hot temparature.
- Psychrophiles: live in low temperatures.
Fungi are referred to the mushroom, molds, and yeasts. They are multicellular, eukaryotic cells, and the chitin is their main cell component. Fungi get their nutrition from the decomposing materials. They absorb their material with the help of a filamentous tube called hyphae. There are present different types of fungi, classified based on their source of nutrients;
- Symbionts: They obtain their nutrients from symbiotic relationships with plants.
- Parasites: They obtain their nutrients from harmful relationships with a host.
- Decomposers: They obtain their nutrients by decomposing organic materials.
They are unicellular and aerobic eukaryotic cells. Their cell wall is made up of cellulose. Protozoa make up the largest group of organisms in the world in terms of numbers, biomass, and diversity. There are present different types of protozoa, they are classified based on their type of locomotions;
- Flagellates: Produces their own food, uses whip-like structure to propel forward.
- Ciliates: contain tiny hair which beat to produce movement.
- Amoeboids: They contain false feet or pseudopodia which are used for feeding and locomotion.
- Sporozoans: They are non-motile.
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They are also known as cyanobacteria or blue-green algae. They may either unicellular or multicellular eukaryotic cells, which obtain their nutrients from photosynthesis. They can found in water, damp soil, and rocks. They produce oxygen and carbohydrates which are used by other organisms.
They are noncellular and containing a nucleic acid core (DNA or RNA) surrounded by a protein coat. Viruses are not living organisms, but they considered as microorganisms.
They are smaller than viruses, contain no genetic particles, but they cause different diseases, including bovine spongiform encephalopathy (mad cow disease), and are suspected of playing a role in a number of other disorders.
Lichens are symbiosis, they remain in association with two different organisms wherein each benefits. They have photosynthetic microbe which is growing in an intimate association with a fungus. Lichens are capable of transforming rock into soil.
9. Slime molds
Slime molds are neither typical fungi nor typical protozoa, they are a biological and taxonomic enigma. In growth phage, they act like a protozoa, because;
- They lack cell walls
- They have amoeboid movement
- They ingest particulate nutrients
In the propagative stage, they produce fruiting bodies and sporangia.