Cyanobacteria – The Blue Green Algae

Cyanobacteria – The Blue-Green Algae

Though often described as algae, blue-green algae are not algae at all, however types of bacteria called cyanobacteria. Cyanobacteria are water living (aquatic) and photosynthetic, and can make their own food. Because they are bacteria, they are quite little and usually unicellular, though they typically grow in colonies large enough to see.

They have the difference of being the oldest recognized fossils, more than 3.5 billion years of ages, in fact. It may shock you then to understand that the cyanobacteria are still around; they are among the largest and essential groups of bacteria in the world.

Structure of Cyanobacteria

Cyanobacteria cells, which are typically one-tenth to one-twentieth the size of eukaryotic cells, are round in shape.

A common cyanobacteria cell includes an external cellular covering, a cytoplasm, and nucleic material. The external cellular covering includes a mucilaginous layer, which secures the cell from ecological elements, a complex, multi-layered cell wall made from polysaccharides and mucopeptides, and an inner living plasma membrane. These are the basics of cyanobacteria structure.


The cytoplasm has actually colored lamellae (membranous folds) around its periphery, derived from the plasma membrane. The pigments include chlorophylls, carotenes, xanthophylls, c-phycoerythrin, and c-phycocyanin. C-phycoerythrin and c-phycocyanin are distinct to blue-green algae.

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The nucleoplasm, where the DNA is located, is comprised of great deals of threadlike fibers or filaments and is in the center of the cell. There is no nuclear boundary or nucleolus. The nucleoplasmic product scattered throughout the cell splits in two throughout the cell division process.

While cyanobacteria cells do not have organelles like mitochondria, chloroplasts, endoplasmic reticulum or Golgi apparatus, which are all present in eukaryotic cells, they both have ribosomes. Ribosomes include RNA (ribonucleic acid) and are responsible for protein synthesis. Ribosomes in cyanobacteria cells are around one-third smaller than ribosomes in eukaryotic cells, but they carry out similar functions.

Attributes of Cyanobacteria

The cyanobacteria are the largest and most diverse group of photosynthetic bacteria which was formerly called ‘blue-green algae’. Cyanobacteria hold true prokaryotes. They vary significantly in shape and appearance. They range in diameter from about 1-10µm and may be unicellular, exist as colonies of many shapes, or type of filaments including trichomes (chains of cells) surrounded by a mucilaginous sheath. They have a regular Gram-negative type cell wall. They lack flagella and often utilize gas vesicles to move in the water, and many filamentous species have moving motility.

Their photosynthetic system closely looks like that of eukaryotes because they have chlorophyll a and photosystem II. They perform oxygenic photosynthesis, i.e., they utilize water as an electron donor and generate oxygen throughout photosynthesis. Cyanobacteria use phycobilins as accessory pigments.

Photosynthetic pigments and electron transportation chain elements are located in thylakoid membranes related to particles called phycobilisomes. Phycocyanin pigment (blue) is their primary phycobilin and CO2 in them is taken in through the Calvin cycle.

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The Reserve food product in cyanobacteria is glycogen. Cyanobacteria reproduce by binary fission, fragmentation. In cyanobacteria hormogonia, akinetes and heterocysts are present.

Blue-green algal blooms

‘ Bloom’ is the term utilized to describe an accumulation of algal cells to a point where they discolor the water, form residues, produce unpleasant tastes and smells, affect fish populations and minimize the water quality. Decomposing algae can likewise cause deficiency of oxygen and cause fish elimination.

Species of blue-green algae might dominate and increase excessively in the water when:

  • nutrient levels, particularly phosphorus and nitrogen are sufficient to support the population growth
  • the ratio of nitrogen to phosphorous concentration is low
  • water is still and turbulence is low (lack of mixing).
  • weather patterns are stable for a week or two.
  • weather is warm (although blooms can take place in cooler weather conditions too).

Blue-green algal blooms frequently continue for numerous weeks, sometimes months, depending primarily on the weather or flow conditions. Cooler, windy weather conditions or increased flow may lower or avoid blooms from taking place.

Economic Importance
  • They assist in the recovery of alkaline soils. Cyanobacteria have heterocysts, which are helpful in the fixation of atmospheric nitrogen.
  • They release O2 in the environment due to their photosynthetic activity.
  • Oscillatoria and few other cyanobacteria can be used as pollution indicators.
  • They have a symbiont relationship with protozoa, fungi, and nitrogen-fixing species form associations with angiosperms. They are photosynthetic partners in the majority of lichen associations.
  • Numerous types of cyanobacteria form water blooms where they frequently impart unpleasant smell and due to big amount of suspended raw material water ends up being unfit for consumption. Some types produce contaminants that kill livestock and other animals that drink the water.
  • Numerous Proterozoic oil deposits are attributed to the activity of cyanobacteria.
  • They are likewise crucial providers of nitrogen fertilizer in the cultivation of rice and beans.
  • The cyanobacteria have actually also been tremendously important in shaping the course of evolution and ecological change throughout earth’s history.
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Cyanobacteria are around 3.5 billion years old group of organisms inhabiting Earth. These are one of the most primitive and successful organisms. The diversity is primarily due to they can live in hot springs as well as icebergs.

Cyanobacteria live as colonies, clusters, in long filaments and sometimes they live as individual cells. As cyanobacteria are autotrophs, so their life activities depend on photosynthesis.

The cyanobacteria have photosynthetic pigments i.e., chlorophyll and carotenoid. They have other pigments called phycobilin. The granules having phycobilin are called phycobilisomes.

Cyanobacteria play an important role in the fixation of atmospheric nitrogen. Heterocysts are the specialized cells where nitrogen fixation take place.