The key difference between bacteria and mollicutes is that bacteria generally possess a peptidoglycan cell wall while mollicutes are a class of bacteria that do not possess a cell wall.
Bacteria are the most abundant microorganisms present in nature. They are a group of unicellular organisms that live everywhere. Furthermore, they are prokaryotic organisms. Hence, they lack a nucleus and membrane-bound organelles. There are different groups of bacteria. Some of them belong to a photosynthetic bacterial group called cyanobacteria. Generally, most bacteria possess a rigid cell wall. However, some bacterial groups do not possess this cell wall. Mollicutes are such a class of bacteria that lack a cell wall. Hence, this article discusses the difference between bacteria and mollicutes.
CONTENTS
1. Overview and Key Difference
2. What are Bacteria
3. What are Mollicutes
4. Similarities Between Bacteria and Mollicutes
5. Side by Side Comparison – Bacteria vs Mollicutes in Tabular Form
6. Summary
What are Bacteria?
Bacteria are prokaryotic microscopic organisms present everywhere. Furthermore, they are unicellular organisms that have a simple cellular organization. They do not possess a nucleus or membrane-bound true organelles such as mitochondria, Golgi bodies, ER, etc. Also, they can exist as a single cell or as colonies. Moreover, they can have several shapes: coccus, bacillus, spirillum, etc. Additionally, they have a cell wall which has a unique peptidoglycan layer. Even the thickness of this peptidoglycan layer changes among bacteria. Based on that, there are two groups of bacteria as Gram-negative and Gram-positive.
Bacteria reproduce mainly by binary fission, which is a mode of asexual reproduction. Other than binary fission, they use several sexual reproduction methods such as conjugation, transformation and transduction, etc. to multiply.
Figure 01: Bacteria
Bacteria contain a small genome composed of a single chromosome in the cytoplasm. Their genes exist as operons, which are clusters expressed under one promoter. Apart from the chromosome, some bacteria contain extra-chromosomal DNA in the form of plasmids. Plasmids are small circular closed DNA. They are not vital for the survival of the bacterium, but they provide additional advantages to bacteria since they contain specific genes. For example, antibiotic-resistant genes are present in the plasmid DNA of bacteria.
Most bacteria are nonpathogenic. However, a small percentage causes diseases such as bacterial pneumonia, tuberculosis, botulism, typhoid, cholera, diphtheria, bacterial meningitis, tetanus, Lyme disease, gonorrhoea, and syphilis.
What are Mollicutes?
Mollicutes are a class of bacteria that do not have a rigid cell wall. In simple words, they are wall-less bacteria. Furthermore, they have a very small genome compared to other bacteria. Their genome ranges between 580 kb to 2200 kb. Mycoplasma is one of the best-known mollicutes. Other two groups are Spiroplasma and Acholeplasma. Mollicutes are simplest and smallest bacteria.
Figure 02: Mollicute – Mycoplasma
Unlike other bacteria, mollicutes are parasites of animals and plants. They live with host organisms and derive nutrients causing diseases. Thus, they are plant and animal pathogens. In humans, Mycoplasma species most commonly colonize mucosal surfaces such as the respiratory and genital tracts.
What are the Similarities Between Bacteria and Mollicutes?
- Mollicutes are a class of bacteria that lack a cell wall.
- Both bacteria and mollicutes are prokaryotes and single-cell organisms.
- They lack membrane-bound organelles.
- They lack a nucleus.
- Furthermore, they have a small genome composed of a single chromosome.
- Both bacteria and mollicutes carry out binary fission.
- Some bacteria and mollicutes are plants and animal pathogens.
What is the Difference Between Bacteria and Mollicutes?
Bacteria are single-celled prokaryotic organisms that contain a rigid cell wall. Meanwhile, mollicutes are a class of bacteria that do not possess a cell wall. So, this is the key difference between bacteria and mollicutes. Furthermore, the bacteria genome is comparatively larger than the genome size of mollicutes. Thus, their size is also a difference between bacteria and mollicutes. Moreover, mollicutes are mostly parasites depending on the host for nutrients, unlike bacteria.
The below infographic shows more details on the difference between bacteria and mollicutes.
Summary – Bacteria vs Mollicutes
Bacteria are ubiquitous microorganisms. They are unicellular organisms having the simplest cell organization. Bacteria have a rigid cell wall composed of peptidoglycan. But, mollicutes are a class of bacteria that lack this rigid cell wall. In summary, this is the key difference between bacteria and mollicutes. Furthermore, mollicutes have a smaller genome than the other bacteria. This is a characteristic feature of mollicutes. Moreover, mollicutes are host-dependent. They obtain nutrients from the host, causing diseases.
Reference:
1. “Mollicutes.” Mollicutes – an Overview | ScienceDirect Topics, Available here.
2. Vidyasagar, Aparna. “What Are Bacteria?” LiveScience, Purch, 25 Apr. 2019, Available here.
Image Courtesy:
1. “1832824” (CC0) via Pixabay
2. “M. haemofelis IP2011” By Nr387241 – Ain wirk (CC BY-SA 3.0) via Commons Wikimedia