The main difference between bacteria and cyanobacteria is that the bacteria are mainly heterotrophs while the cyanobacteria are autotrophs. Furthermore, bacteria do not contain chlorophyll while cyanobacteria contain chlorophyll-a.
Bacteria and cyanobacteria are the two types of prokaryotes that do not contain membrane-bound organelles such as nucleus, mitochondria, chloroplasts, Golgi, ER, etc.
Key Areas Covered
1. What are Bacteria
– Definition, Characteristics
2. What are Cyanobacteria
– Definition, Characteristics
3. What are the Similarities Between Bacteria and Cyanobacteria
– Outline of Common Features
4. What is the Difference Between Bacteria and Cyanobacteria
– Comparison of Key Differences
Key Terms
Bacteria, Cyanobacteria, Chlorophyll-a, Photosynthesis, Prokaryotes
What are Bacteria
Bacteria are unicellular prokaryotes that can live in diverse environments. The cellular structure of bacteria is simple and do not contain any membrane-bound organelles. The genetic material of bacteria is a single, circular DNA molecule located at the nucleoid. Bacteria contain 70S ribosomes. All metabolic reactions occur inside the cytoplasm in bacteria. The cell wall of bacteria mainly contains a polysaccharide called murine. Some bacteria do not have a cell wall and they are called mycoplasma.
Figure 1: Bacteria
There are two main types of bacteria as Gram-positive and Gram-negative. The cell walls of Gram-positive bacteria are rich in peptidoglycans. The three basic shapes of bacteria are bacillus, coccus, and spirillum. Asexual reproduction of bacteria mainly occurs through binary fission while sexual reproduction occurs through conjugation.
What are Cyanobacteria
Cyanobacteria are unicellular or multicellular prokaryotes that can undergo photosynthesis. They are also called blue-green algae. They live in the soil, freshwater or marine habitats and can tolerate harsh environmental conditions same as bacteria. Cyanobacteria can form spherical-shaped, filamentous or sheet-like colonies covered with mucilaginous, sheet-like structures. Heterocysts are the nitrogen-fixing cyanobacteria.
Figure 2: Cyanobacteria
The main photosynthetic pigment of cyanobacteria is chlorophyll-a while the accessory pigments are phycocyanin and phycoerythrin. However, some cyanobacteria are saprotrophs. Blooming cyanobacteria produce cyanotoxins that can be poison to humans and animals.
Similarities Between Bacteria and Cyanobacteria
- Bacteria and cyanobacteria are prokaryotes.
- They do not contain membrane-bound organelles such as nucleus, mitochondria, chloroplasts, Golgi, ER, etc.
- Their ribosomes are 70S and they do not contain true vacuoles or well-developed plastids.
- Their cell wall contains muramic acid and diaminopimelic acid.
- Both contain a mucilaginous sheath around the cells.
- They can fix atmospheric nitrogen.
- Both form spores as resting units.
- These organisms are resistant to desiccation and high temperature.
- They undergo asexual reproduction.
- Both form colonies.
- They can cause diseases in other organisms.
- Both have similar sensitivity to antibiotics.
Difference Between Bacteria and Cyanobacteria
Definition
Bacteria refer to a member of a large group of unicellular microorganisms which have cell walls but lack organelles and an organized nucleus, including some which can cause disease while cyanobacteria refer to a division of microorganisms related to bacteria but are capable of photosynthesis.
Distribution
Bacteria occur in each and every habitat on earth while cyanobacteria mainly occur in the presence of sunlight and moisture.
Size
The bacteria are small while cyanobacteria are comparatively large.
Unicellular/Multicellular
Bacteria are unicellular while cyanobacteria can be either unicellular or multicellular.
Cell Wall
The cell wall of bacteria can be either one or two layers while the cell wall of cyanobacteria is made up of four layers. Furthermore, glycolipids and peptidoglycans are the main components of a bacterial cell wall while cellulose and pectin are the main components of the cell wall of cyanobacteria.
Gram-Positive/Negative
Bacteria can be either Gram-positive or -negative while cyanobacteria are Gram-negative.
Flagella
Some bacteria contain flagella while cyanobacteria lack flagella. Therefore, some bacteria are mobile while cyanobacteria are immobile.
Photosynthetic Pigments
Some bacteria contain photosynthetic pigments such as bacteriochlorophyll while cyanobacteria contain chlorophyll-a. Furthermore, cyanobacteria contain accessory pigments such as phycocyanin and phycoerythrin.
Mode of Nutrition
Most bacteria are heterotrophs while cyanobacteria are autotrophs.
Photosynthesis
Photosynthesis is anoxygenic in bacteria, means they do not produce oxygen at the end of the photosynthesis, while it is oxygenic in cyanobacteria.
Reserved Food
Glycogen is the reserved form of food in bacteria while cyanophycean starch is the reserved form of food in cyanobacteria.
Heterocyst Formation
Bacteria do not form heterocysts while cyanobacteria form heterocysts, which are the nitrogen-fixing cells.
Sexual Reproduction
Sexual reproduction of bacteria occurs through conjugation, transformation or transduction while sexual reproduction is absent in cyanobacteria.
Conclusion
Bacteria are unicellular prokaryotes that are mainly heterotrophs. Cyanobacteria can be either unicellular or multicellular prokaryotes and are mainly autotrophs. They are mainly photosynthetic. Therefore, the main difference between bacteria and cyanobacteria is the mode of nutrition.
Reference:
1. Vidyasagar, Aparna. “What Are Bacteria?” LiveScience, Purch, 23 July 2015, Available Here
2. “Introduction to the Cyanobacteria.” Basic Flight Physics, Available Here
Image Courtesy:
1. “Prokaryote cell” By This vector image is completely made by Ali Zifan – Own work; used information from Biology 10e Textbook (chapter 4, Pg: 63) by: Peter Raven, Kenneth Mason, Jonathan Losos, Susan Singer · McGraw-Hill Education. (CC BY-SA 4.0) via Commons Wikimedia
2. “CyanobacteriaColl1” By Christian Fischer (CC BY-SA 3.0) via Commons Wikimedia
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