Bacteria - General characteristics

It gives a general idea about bacteria- shape, size and structure. It is a part of Microbiology Syllabus in BSc (CBCS) system both Hons and Program

1. CC-1 (CBCS) Hons Program Unit-3: Bacteria General characteristics; Cell structure Ref : Peltzar ; Dr. Rita Som Paul Associate Professor Botany Department Siliguri College Siliguri

2. General characteristics I. Size – typically 0.5 m m – 5.0 m m Largest bacterium discovered – Thiomargarita namibiensis 750 m m –visible to the naked eye Smallest bacterium- Mycoplasma genitalium 200-300nm (0.2-0.3 m m)

3. Thiomargarita namibiensis

4. II. Bacterial shape 1. Sperical (coccus) Rod-shaped 3. Spiral – spirillum (rigid rod) Spirillum volutans 4. Helix (flexible )- spirochete Treponima pallidum 2.Bacillus 5.Filamentous- Actinomycetes Eg . Streptomeces spp 3. Coma-shaped Vibrioid Vibrio colerae

5. Bacterial arrangement in coccus 3. Chains : streptococc i Eg Streptococcus lactis 2. Diplococc i – in pairs Eg Diplococcus pneumoniae 6. Clusters : staphylococc i Eg . Staphylococcus aureus 5. Packets of eight:sarcina e Eg Sarcina lutea 1.Singly- Micrococci Eg . Micrococcus luteus 4. Tetracocci - four cells Pedicoccus cerevosae

6. Rod-shaped or bacillus 1. Single – Lactobacillus, Bacillus anthracis 2. In pairs – Diplobacillus Corynebacterium diphtheriae 3. In chains – streptobacillus Bacillus cereus, B. tuberculosis