PPLO, in zoology, stands for pleuropneumonia-like organisms. They are a type of bacteria also known as Mycoplasma.
Understanding PPLO
PPLO, or Mycoplasma, are unique among bacteria because they lack a cell wall. This characteristic makes them highly pleomorphic, meaning they can take on various shapes and sizes, and also makes them resistant to many common antibiotics that target cell wall synthesis.
Key Characteristics of PPLO:
- Cell Wall Absence: The defining feature of PPLO is the lack of a rigid cell wall, a common structure in most bacteria.
- Small Size: They are among the smallest free-living prokaryotic organisms, often measuring just 0.1 to 0.3 micrometers in diameter.
- Pleomorphic Nature: Due to the lack of a cell wall, PPLO can change their shape, exhibiting different forms such as coccoid (spherical), filamentous (thread-like), or ring-shaped.
- Prokaryotic: They are prokaryotes, which means they are single-celled organisms with no nucleus or other membrane-bound organelles.
- Free-Living Organisms: PPLO are known as free-living organisms.
Why are Mycoplasmas Called PPLO?
The term "pleuropneumonia-like organisms" was given to these bacteria due to their initial discovery and association with diseases like bovine pleuropneumonia, which causes inflammation of the lungs and chest cavity. These organisms were different from known bacteria and were later categorized under the genus Mycoplasma. Hence, both terms are now used interchangeably.
| Feature | PPLO (Mycoplasma) |
|---|---|
| Cell Wall | Absent |
| Size | Very small (0.1 - 0.3 µm) |
| Shape | Pleomorphic (various forms) |
| Classification | Prokaryotic, Bacteria, genus Mycoplasma |
| Common Name | Pleuropneumonia-like Organisms |
Medical Importance
Mycoplasmas are significant because they can cause various diseases in humans, animals, and plants. Examples include:
- Human Infections: Mycoplasma pneumoniae causes atypical pneumonia (walking pneumonia).
- Animal Infections: Bovine pleuropneumonia is caused by Mycoplasma mycoides.
- Plant Diseases: Mycoplasmas are also known to cause yellow diseases in plants.
The lack of a cell wall makes them resistant to antibiotics like penicillin which target cell wall synthesis. This poses a challenge in treating mycoplasmal infections.
