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Depending on the shapes, bacteria are classified into three types.
Important!
Spherical shaped - Cocci
Rod-shaped - Bacilli
Spiral shaped - Spirilla
Rod-shaped - Bacilli
Spiral shaped - Spirilla
Types of bacteria on basis of shape:
Types | Arrangement of cocci | Examples |
| Diplococci | Arranged in pairs | Streptococcus pneumoniae |
| Streptococci | Arranged in chains | Streptococcus pyogenes |
| Tetracocci | Arranged in packets of four cells | Aerococcus sp |
| Staphylococci | Arranged in grape-like clusters | Staphylococcus aureus |
Types | Arrangement of bacilli | Examples |
| Diplobacilli | Arranged in pairs | Klebsiella sp |
| Streptobacilli | Arranged in chains | Streptobacillus sp |
| Coccobacilli | Arranged in short, stumpy and appear ovoid | Haemophilus sp |
Types | Arrangement of spirilla | Examples |
| Vibrio | Comma-shaped bacteria | Vibrio cholerae |
| Spirilla | Rigid spiral structure | Helicobacter pylori |
| Spirochetes | Helical shape and flexible bodies | Treponema pallidum |
The main forms of bacteria
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