Inoculation loop
Encyclopedia
An inoculation loop, also called a smear loop, inoculation wand or microstreaker, is a simple tool used mainly by microbiologist
s to retrieve an inoculum from a culture
of microorganisms. The loop is used in the cultivation of microbes on plates by transferring inoculum for streaking
.
The wire forms a small loop with a diameter of about 5 mm. The loop of wire at the tip may be made of platinum
or nichrome
, the latter being inferior but less expensive. This loop removes a consistent amount of the liquid suspended inoculum by using the phenomenon of surface tension
.
The inoculation loop is sterilized
in a flame until it becomes red-hot before and after each use. By doing this, the same tool can be reused in different experiments without fear of cross-contamination. After flame sterilization, the loop must be cooled so that the next cells the loop touches are not killed by the hot metal.
Microbiologist
A microbiologist is a scientist who works in the field of microbiology. Microbiologists study organisms called microbes. Microbes can take the form of bacteria, viruses, fungi, and protists...
s to retrieve an inoculum from a culture
Microbiological culture
A microbiological culture, or microbial culture, is a method of multiplying microbial organisms by letting them reproduce in predetermined culture media under controlled laboratory conditions. Microbial cultures are used to determine the type of organism, its abundance in the sample being tested,...
of microorganisms. The loop is used in the cultivation of microbes on plates by transferring inoculum for streaking
Streaking (microbiology)
In microbiology, Streaking is a technique used to isolate a pure strain from a single species of microorganism, often bacteria. Samples can then be taken from the resulting colonies and a microbiological culture can be grown on a new plate so that the organism can be identified, studied, or...
.
The wire forms a small loop with a diameter of about 5 mm. The loop of wire at the tip may be made of platinum
Platinum
Platinum is a chemical element with the chemical symbol Pt and an atomic number of 78. Its name is derived from the Spanish term platina del Pinto, which is literally translated into "little silver of the Pinto River." It is a dense, malleable, ductile, precious, gray-white transition metal...
or nichrome
Nichrome
Nichrome is a non-magnetic alloy of nickel, chromium, and often iron, usually used as a resistance wire. Patented in 1905, it is the oldest documented form of resistance heating alloy. A common alloy is 80% nickel and 20% chromium, by mass, but there are many others to accommodate various...
, the latter being inferior but less expensive. This loop removes a consistent amount of the liquid suspended inoculum by using the phenomenon of surface tension
Surface tension
Surface tension is a property of the surface of a liquid that allows it to resist an external force. It is revealed, for example, in floating of some objects on the surface of water, even though they are denser than water, and in the ability of some insects to run on the water surface...
.
The inoculation loop is sterilized
Sterilization (microbiology)
Sterilization is a term referring to any process that eliminates or kills all forms of microbial life, including transmissible agents present on a surface, contained in a fluid, in medication, or in a compound such as biological culture media...
in a flame until it becomes red-hot before and after each use. By doing this, the same tool can be reused in different experiments without fear of cross-contamination. After flame sterilization, the loop must be cooled so that the next cells the loop touches are not killed by the hot metal.