Morphology

MORPHOLOGY

Morphology relates to the ‘science dealing with the structures and forms of organisms’. In reality, the ‘morphology of the bacterium’ exclusively trusts confidently upon a number of factors, namely :

·        the strain under investigation,

·        nature of the culture medium,

·        temperature and time of incubation,

·        age of the culture, and

·        the number of ‘subculture’ it has been subjected to.

Importantly, the various characteristic features that may be observed from such meticulous investigational studies are : shape, size, arrangement, motility, flagella, spores, and capsules.

The variants observed in the above cited physical characteristic features may be stated as under :

Shape : spherical, rod shaped, comma shaped, spiral shaped, filamentous.

Axis of organism : straight, curved.

Length and breadth : mostly variable.

Sides of organism : convex, concave, parallel, irregular.

Ends of organism : tapering, rounded, straight.

Shape : club shaped, giant forms, navicular, swollen, shadow shaped.

Arrangement : in pairs, in tetrads, packs of eight, in chains (short or long) e.g., cocci ; in short and long chains at random e.g., bacilli ; in single or in ‘S’ or in spiral forms .e.g., vibrios.

Motility : non-motile, sluggishly motile, actively motile or may show darting motility.

Forms : atrichate (i.e., without flagella) ; monotrichate ; lophotrichate ; amphitrichate ; peritrichate ;

Spores : oval, spherical, ellipsoidal, having same width or wider than the prevailing bacillary body ; equatorial, subterminal or terminal.

Capsules : may or may not be present.

Techniques used : Electron microscopy ; phase-contrast microscopy ; background illumination ; and hanging drop preparations.