Cultural characteristic of bacteria is one of the important aspect applied in identification of bacteria. Cultural characteristics describe various features of growth of bacteria on medium.
Growth on solid media
Size – in mm
Shape – Round, irregular, rhizoid, spindle
Elevation – Flat, raised, convex, umbonate
Surface – Smooth, rough, papillate, ringed, fried egg, medusa head
Margins – Entire, wavy, lobate, erose, curled,filamentous
Opacity – Opaque, translucent, transparent
Consistancy – Butyrous, friable, viscid
Emulsifiability – Easy, difficult, forms homogenous or granular suspension.
Growth on slant
Amount – Scanty, moderate, abundant
Form – Spreading, filiform, rhizoid
Growth in stab
Amount – Scanty, moderate, abundant
Form – Papillate, filiform, beaded, arborescent
Surface growth- Absent, present, colouration
Liquification – forming layer, like cup, like turnip, like funnel, tubular
Growth in liquid media
Amount – Scanty, moderate, abundant
Surface growth- Absent,present, ring, pellicle (thin, thick, smooth, granular)
Deposit -Absent,present(slight, moderate, abundant, powdery, viscid)
Turbidity – Absent,present
Odour – Absent,present
Exercise
Q1.Describe the colony characteristics of Escherichia coli on MacConkey’s agar medium.
Q2.Describe cultural characters of Staphylococcus aureus in Nutrient Broth.