Autore Bruno Pacifici

Architettura dei batteri: il batterio virtuale

La grandezza, forma, composizione dei batteri, e degli altri microbi, è il risultato dei loro geni. Le forme batteriche più comuni sono i bastoncelli, cocchi, e le spirali. Comunque, in ognuno di questi gruppi ci sono centinaia di variazioni. I bastoncelli possono essere lunghi, corti, fini, spessi, possono finire tondi o a punta, essere più fini da una parte che dall’altra etc. I cocchi possono essere larghi, piccoli, o più o meno ovali. Quelli a spirale, fini, poco spiralati o molto spiralati. I batteri possono esistere principalmente come singole cellule o come raggruppamento comune in catene , gruppo irregolare, coppie, tetradi, ottetti, e altri pacchetti. Possono esistere come masse racchiuse in capsule. Ci sono batteri quadrati, a forma di stella, con flagello, batteri gemmanti che crescono in formazioni a rete e molte altre morfologie.

Size varies from 0.2 - 60 µm.
There are 4 basic shapes - spherical, rods, spiral and square.

Spherical is called coccus.
Division along the same plane forms chains; 2 cocci together - Diplococcus
4 - 20 in chains - Streptococcus.
Division along 2 different planes - Tetrads
Division along 3 planes regularly - Sarcinae
Division along 3 planes irregularly - Staphylococci

Rod shape is called Bacillus.
Two bacilli together - Diplobacilli
Chains of bacilli are called Streptobacilli
Palisades - Rods side by side or in X, V or Y figures

Spiral shape that is rigid is called Spirillium.
If the organism is flexible and undulating, it is called Spirochete.

Square shape is called Archaebacteria.
Pleomorphism - Different forms of the same species.

Electron micrograph of E. coli. This is an electron micrograph of a common Gram negative bacteria that resides in the intestines of most vertebrates on the planet. In size it is approximately 1 to 2 micrometers in length by 0.5 to 1.0 micrometers in width. These cells are actively growing as can be seen by the number of cells that are in the process of cell division or binary fission. Some of them look to be ready to separate and others appear to be just beginning to form their "cross walls". Their surface appears to be covered with a sort of fuzzy material. This "fuzz" is composed of lipopolysaccharide (LPS) and capsular material that covers the outer portion of the cell. These substances serve as a sort of armor to protect the cells.

Campylobacter. This is an electron micrograph of a spiral-shaped gram negative, bacterium, Campylobacter that is an important intestinal pathogen. Dr. M. Konkel in the WSU Microbiology department is investigating the pathogenic determinants in this bacteria.

Componenti cellulari dei batteri

Composite cartoon showing the major structures found in bacteria. No one bacteria contains all of these different components, but most bacteria contain the majority of them.