Shapes And Arrangements Of Bacteria

Microbiology

Size, Shapes and Arrangements of Bacteria

Bacterial Shapes

• cocci • bacilli • spiral

Coccus

Cocci (pl.) are spherical or oval bacteria having one of several distinct arrangements based on their planes of division.

Arrangements of Cocci • division in one plane – diplococcus (pairs) – streptococcus (chains)

• division in two planes – tetrad (squares of four)

• division in three planes – sarcina (cubes of eight)

• random planes

Diplococcus

Streptococcus pneumoniae

Streptococcus

Streptococcus pyogenes

Tetrad

Micrococcus luteus

Sarcina

Sarcina Spp.

Random/Clusters

Staphylococcus aureus

Bacillus

Bacilli (pl.) are rod-shaped bacteria. Bacilli all divide in one plane producing a bacillus, streptobacillus, or coccobacillus arrangement.

Arrangment of Bacilli • • • •

bacilli (single) diplobacilli (pairs, few) streptobacilli (chains) coccobacilli (oval)

Bacilli

Pseudomonas aeruginosa

Diplobacilli

Moraxella catarrhalis

Streptobacilli

Bacillus subtilis

Coccobacilli

Bortedella pertussis

Spiral

Spirals come in one of three forms: – vibrio (comma-shaped) – spirillum (thick, rigid spiral) – spirochete (thin, flexible spiral)

Vibrio

Vibrio cholerae

Spirillum

Spirillum volutans

Spirochete

Treponema pallidum

Leptospira interrogans

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