Bacterial Colony Description

bacterial colony description' bacteria

can be grown on an agar plate which is

called culturing when bacterial grown on

an agar plate they consume the nutrients

within the medium

each single bacterial cell replicates

many times to generate millions of cells

that form a single bacterial colony on

the plate the appearance of these

colonies is termed colony morphology

describing colony morphology is the

first part of identifying and

characterizing a bacterial culture

because individual bacterial species

often form colonies of characteristic

size and appearance the four main

characteristics we use to describe

bacterial colonies are size shape color

and any other distinguishing features

such as whether the colony surface is

glassy slimy smooth or dry

here we have bacterial colonies growing

on a blood agar plate it's called blood

agar because it contains horse blood

blood agar is one of the most routinely

used egg as as it contains many

nutrients suitable for even the most

fastidious bacteria note that there are

two colony types growing on this blood

agar plate the colony morphology of the

smaller colony would be described as

white round and 2 millimeters in


the second colony type would be

described as gray of an irregular shape

and about 3 to 6 millimeters in diameter

some bacteria also cause lysis of the

red blood cells in the agar this is

described as hemolysis the best way to

check for hemolysis is to hold the plate

up to the light like so look for

clearing of the opaque red blood cells

in the zone surrounding each colony note

the plate on the left has complete

degradation of the red blood cells this

is called beta hemolysis while the plate

on the right has only partial

degradation of red blood cells this is

called alpha hemolysis note the greenish

tinge around these bacterial colonies