“Aseptic” are used to make microbial cultures, which

“Aseptic” means free from contamination caused by any
microorganism that is not of interest to the scientist. Aseptic technique means
using practices and procedures to prevent contamination from microorganisms,
including the use of sterile media and equipment, as well as proper handling
procedure. Aseptic technique is used in microbiology because it is essential for
identification of a microbe; in order to study an organism, it must first be
isolated.

 

Media, or singular medium, is a broth-like liquid or gel-like
solid designed to support the growth and/or selection of cells. Most commonly,
agar petri plates or tubes of liquid broth are used. Specialized media are
sometimes required for microorganism and cell culture growth. Media is used in
microbiology to grow enough cells for characterization or experimentation. Media
can also be utilized, such as in the streak-plate method, to obtain pure
cultures. Media are used to make microbial cultures, which are used to
determine the type of organism, its abundance in a sample, and for selective or
differential growth. If media is not kept sterile, microorganisms other than
the microbe of interest can be introduced; if aseptic technique is not
maintained, there is no guarantee that the culture/colonies grown are from the
species of interest. Good scientific method requires that experiments should be
designed to minimize possible errors, especially through the use of appropriate
controls, such as aseptic technique to isolate the independent variable.

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The lid of a petri dish or culture tube should never be laid
on the table or benchtop when inoculating because contamination may be
introduced to the culture.

 

The bottom of a petri dish should be labeled, rather than
the lid; lids can accidentally be switched. Labelling on the bottom ensures
that the written information stays with the intended culture, even if the lid
gets accidentally exchanged with another plate.

 

Petri dishes are incubated in an inverted position to
prevent condensation that can disturb a culture, and to lessen the risk of
contamination from airborne particles settling on them.

 

An inoculating loop is an instrument used to transfer bacteria
from one medium to another.

 

Visible bacterial growth in a culture tube is referred to as
a _____culture______.

 

A colony is a visible, discrete clump of bacteria growing on
the surface of solid media. Each individual colony represents the descendants
of a single cell.

 

Colony morphology is a method that scientists use to
describe the characteristics of an individual colony of bacteria growing on
agar in a petri dish; it can be used to help to identify them. Colonies are
described according to size, shape, texture, opacity, elevation, pigmentation,
effect on growth medium, etc.