APPLIED MICROBIOLOGY, Jan. 1972, p. 174-176Copyright © 1972
American Society for Microbiology
Vol. 23, No. 1Printed in U.S.A.
Inoculation Technique for Fungus CulturesRAMON M. FUSARO
Department of Dermatology, The University of Nebraska Medical
Center, Omaha, Nebraska 68105
Received for publication 23 August 1971
A plastic straw and wood applicator stick serve as a simple,
inexpensive, anddisposable inoculation unit for fungal studies. The
method gives a uniform andintact inoculum. The technique is
especially useful because a large number ofagar plates can be
inoculated rapidly.
To inoculate a large number of Sabouraudagar plates with a
fungus, the standard tech-niques can be time-consuming and do not
al-ways give uniform (diameter) inoculations.The following is a
description of a simple, in-expensive, and disposable method.The
materials consist of plastic drinking
straws (4 mm in diameter by 26 cm in length;Carnival Straws
Supra Plastic, National SodaStraw Co., Chicago, Ill.), which were
cut intothirds, and 6-inch (ca. 15.2 cm) wood appli-cator sticks. A
single applicator stick is in-serted into each straw and
gas-sterilized(ethylene oxide).
Prior to the inoculation, a hole is made inthe center of the
agar with another plasticstraw without an applicator stick (Fig.
1). Thesterile agar core cut by the plastic straw willremain within
the tip of the straw when thestraw is withdrawn by sealing the
other openend of the straw with the finger tip (Fig. 2).The same
straw can then be used to remove 5to 10 more sterile agar cores
from other platesas the entrapped agar cores act as
suctionplugs.
When using the inoculating unit (plasticstraw with wood
applicator stick), the middleportion of the straw is grasped and
squeezed tohold the stick within the straw. The applicatorstick is
pulled up into the tube so that its endis approximately 1 to 2 cm
from the distal endof the plastic straw which will be inserted
intothe fungus colony growing on Sabouraudagar. After punching to
the bottom of the platethrough the agar (Fig. 3), the straw is
rolledbetween the fingers to sever the core. Thestraw is then
tilted to break the adhesive forceof the agar plug to the petri
plate. The unit islifted out and the tip of the plastic straw
con-taining the fungus plug is placed into the agarhole in the
recipient plate (Fig. 4). The appli-cator stick is pushed gently
down against theagar plug while the plastic straw is liftedslowly
out of the agar hole, thereby placing theinoculum in the agar hole
(Fig. 5).
It should be emphasized that the inoculumis uniform in diameter
only, not cell number.The time necessary to inoculate many plates
isminimal.
174
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