Cyanobacteria (blue-green algae) are among the most common organisms on the planet. They first appeared more than 3.5 billion years ago, reshaping our entire biosphere.
- Cyanobacterial photosynthesis is thought to have enriched Earth's early atmosphere with oxygen, giving rise to life.
- Cyanobacteria have evolved over time to adapt to various geochemical and climatic changes.
- Modern cyanobacteria have learned to take advantage of human-made changes to aquatic environments.
- Overnutrition and hydrologic changes have had a significant impact on global water ecosystems.
- Cyanobacterial blooms have become a global concern as a result of climate change and its consequences.
Key words: Cyanobacteria, Bacteria, Algae, Nutrient, Cyanobacterial bloom.
What are Cyanobacteria?
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Cyanobacteria are microorganisms that resemble bacteria in structure but lack a nucleus and organelles. Cyanobacteria, unlike other bacteria, can perform oxygenic photosynthesis and contain chlorophyll a. (chl-a).
- Cyanobacteria have an amazing ability to adapt to global changes.
- They can withstand high UV light, desiccation, hypersalinity, and extreme temperatures for many years.
- These organisms can be found in freshwater lakes, streams, oceans, damp soil, moistened rocks, and other environments.
- They have formed unique symbiotic relationships with microorganisms, plants, seagrass, fungi, sponges, and cycads over billions of years of evolution.
- Cyanobacteria are too small to see without a microscope, but they can grow into massive colonies that can be seen from space.
- Cyanobacterial blooms can be extremely harmful to humans, animals, and ecosystems.
Classification of Cyanobacteria
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Cyanobacteria were previously known as Cyanophyta in the five-kingdom classification scheme and are one of the phyla of the Kingdom Protista. Euglenophyta, Chrysophyta, Pyrrophyta, Chlorophyta, Phaeophyta, and Rhodophyta are the other phyla.
- Because of their photosynthetic ability, these phyla are groups of plant-like protists.
- Unlike embryophytes, they lack true roots, stems, and leaves.
- Cyanophyta (also known as blue-green algae) is now known as Cyanobacteria, a phylum of bacteria.
- This is due to the fact that this clade is made up of prokaryotic species.
- Blue-green algae are the only prokaryotic algae in phycology; the rest are eukaryotes.
- As a result, they are now classified as bacteria of the Phylum Cyanobacteria.
- The specific classification of cyanobacteria is as following;
- Kingdom - Monera
- Division - Eubacteria
- Class - Cyanobacteria
- Order -Nostocaceae
- Genus - Nostoc
- Common Name - Star Jelly
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Sub-groups of Cyanobacteria
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Based on morphology, cyanobacterial subgroups are classified as follows:
- Chroococcales
- Pleurocapsales
- Oscillatoriales
- Nostocales
- Stigonematales
Characteristics of Cyanobacteria
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Cyanobacteria characteristics are as following;
- There is an immature nucleus present.
- The presence of a ribosome of the 70s type
- There is a gas vacuole present.
- They are autotrophic, and photosynthesis is accomplished through oxygenic photosynthesis.
- Double membrane-bound cell organelles such as the ER, Golgi body, and plastids are not present.
- There are no locomotory organelles present.
- Sexual reproduction is not present.
- Reproduction is completed through the asexual method.
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Cyanobacterial Blooms- A Threat to the Environment
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The spread of cyanobacterial Harmful Algal Blooms (cyanoHABs) has become a major concern for societies all over the world. Cyanobacteria can seriously compromise the safety of drinking water, as well as the value of fishing, irrigation, and recreational activities.
- CyanoHABs deplete the oxygen in the water, cause toxins to be released, and degrade water quality.
- Cyanobacterial blooms cause fish and plants to suffocate and die.
- They endanger the water's quality and safety for animals and humans by releasing cyanotoxins into it.
- When the cyanobacteria in the bloom begin to decompose, they emit unpleasant tastes and odors.
Economic Implications
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Many business sectors may suffer economic losses as a result of cyanoHABs. They have a significant financial impact on the agricultural sector, fisheries, water treatment plants, tourism industries, recreational services, and waterfront real estate prices.
Cyanobacteria and Nutrient Pollution
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Cyanobacteria are actively exploiting human-caused water pollution. Nutrient pollution and eutrophication are beneficial to them.
- Nutrient contamination, salinization, and eutrophication of streams are all exacerbated by urban, agricultural, and industrial activity.
- Organisms become more common and chronic as a result of this.
- Cyanobacterial blooms are becoming more common as a result of climate change.
- More frequent and extensive cyanoHABs are induced by rising temperatures and changing precipitation patterns.
- Thermal stratification occurs early and lasts longer at higher temperatures, making them buoyant cyano bacillus more buoyant.
Things to Remember
- Cyanobacteria played an important role in the evolution of aerobic forms of life.
- In a hostile environment, they provide suitable conditions for the growth of other organisms.
- They convert atmospheric nitrogen into ammonium compounds, and the excess is excreted into the soil, enriching it.
- Nitrogen fixation is carried out by approximately 50 species of cyanobacteria.
- They are classified into two types based on nitrogen fixation: free-living N2-fixing cyanobacteria and non-free-living N2-fixing cyanobacteria
- Examples are Anabaena, Nostoc, Aulosira, Scytonema. Tolypothrix Stigonema, Gloetrichia etc.
- Symbiotic N2-fixing cyanobacteria (such as Nostoc and Anabaena) are common in Anthoceros lichens.
- Azolla and Cycas root; Anabaena azollae is found in the flora of Azolla pinnata.
- They serve as bio-fertilizers.
- Mosquito larvae are not allowed to grow in Anabaena and Aulosira.
- Lyngbya, a cyanobacterium extract, is used in the production of antibiotics.
- Some hydrogen-producing cyanobacteria, in addition to algae, are being considered as an alternative energy source.
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Sample Questions
Ques: Are cyanobacteria beneficial or harmful? (2 marks)
Ans: Not all algal blooms are toxic. A cyanobacterial algal bloom can be toxic when the pollutants it produces in the air and water, known as cyanotoxins, reach levels that are harmful to people, marine life, and the environment.
Ques: Can cyanobacteria cause illness? (2 marks)
Ans: Cyanobacteria blooms can deprive other organisms of the oxygen and nutrients they require to survive. cyanotoxins, which are toxins produced by bacteria. Cyanotoxins are some of nature's most potent poisons. They have the potential to make people, their pets, and other animals ill.
Ques: What are the signs and symptoms of cyanobacteria? (2 marks)
Ans: Symptoms of cyanobacterial toxins in water include headaches, nausea, fever, sore throat, dizziness, stomach cramps, diarrhea, abdominal pain, vomiting, muscle aches, mouth ulcers, and lip blistering.
Ques: Is it possible to get rid of blue-green algae? (2 marks)
Ans: When excess nutrients are no longer flowing into the lake, there will be no more food for the algae, and they will cease to multiply and die. The blooms may vanish as quickly as they appeared, especially in windy or rainy conditions, or it may take a few days to a week or two.
Ques: Is it possible to extract blue-green algae by boiling it? (2 marks)
Ans: No, Boiling water will not destroy the toxins. Boiling the water causes the blue-green algae cells to burst, releasing toxins into the water and increasing the likelihood of experiencing symptoms.
Ques: Why do yellow algae keep reappearing? (3 marks)
Ans: Most pools require at least 12 hours of daily filtering while the sun is shining during the hotter summer months to keep chlorine circulating and to remove small particles that cloud the pool, providing algae with some UV protection. Algae will return if you only filter the pool for 8-10 hours per day.
Ques: What is the significance of cyanobacteria? (2 marks)
Ans: Cyanobacteria play an important role in the formation of the earth's oxygen atmosphere, and it has also contributed to many other aspects of human life. Cyanobacteria are often referred to as "blue-green algae" because they are photosynthetic and aquatic.
Ques: What is the role of cyanobacteria? (3 marks)
Ans: Cyanobacteria have the ability to fix atmospheric N2, decompose organic wastes and residues, detoxify heavy metals, pesticides, and other xenobiotics, catalyze nutrient cycling, suppress the growth of pathogenic microorganisms in soil and water, and produce some bioactive compounds that contribute to plant growth.
Ques: Is cyanobacteria harmful to aquariums? (3 marks)
Ans: Cyanobacteria in aquariums do not usually harm fish, but they can kill plants if the leaves become covered and they can no longer photosynthesize light. Blue-green algae are also distinguished by its distinct odor. Earthy, musty, swampy, and foul have all been used to describe the odor.
Ques: What is it that cyanobacteria can do that bacteria cannot? (1 marks)
Ans: Cyanobacteria are producers, which means that they can produce their own food (autotrophs). They do photosynthesis which other bacteria cannot perform.
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