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A rotating transfer needle for liquid cultures
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TECHNIQUES A ROTATING TRANSFER NEEDLE FOR LIQUID CULTURES
D.A. Seaby Some fungi including mycorrhiza forming ones grow best in liquid media. However sterile sub-culturing can be difficult if they form compact growth which is difficult to break up using a nichrome needle even if it is flattened and sharpened. If clumps can be broken up it is still difficult to lift these from the liquid. By using a rotating needle, strands of mycelium growing in liquid culture can be rapidly entangled facilitating their transfer. The needle can also be used for gently breaking up colonies for other purposes. Construction of the device is illustrated in Fig.1 and the circuit diagram in Fig.2. The materials required are One piece of aluminium sheet, 3cm x llcm, one push button contact switch, one three position on-off-on switch; One small model makers electric motor approximately 3cm x 3cm; Two telescoping pieces of fine metal tubing approximately 2mm and 4mm diameter as used by model makers ; One piece of 24 gauge nichrome wire, 25cm long; this must be straight so that it does not rub on the metal tubing sheathing it. One small coil spring.
For use, the telescopic sheath is adjusted so that approximately Scm of needle protrudes. To trap hypha! strands the needle is rotated in short bursts by moving the switch to position I and then briefly pressing the push button contact. Prolonged rotation causes the strands to become tightly wrapped around the needle and contra rotation is necessary to free them To use the needle for breaking up colonies the telescopic sheath is moved so that 6 - 7em of needle are exposed and the switch turned to the permanently on position (2) when the needle rotates rapidly and flexes giving a whisking motion.
TECHNIQUES A ROTATING TRANSFER NEEDLE FOR LIQUID CULTURES
D.A. Seaby Some fungi including mycorrhiza forming ones grow best in liquid media. However sterile sub-culturing can be difficult if they form compact growth which is difficult to break up using a nichrome needle even if it is flattened and sharpened. If clumps can be broken up it is still difficult to lift these from the liquid. By using a rotating needle, strands of mycelium growing in liquid culture can be rapidly entangled facilitating their transfer. The needle can also be used for gently breaking up colonies for other purposes. Construction of the device is illustrated in Fig.1 and the circuit diagram in Fig.2. The materials required are One piece of aluminium sheet, 3cm x llcm, one push button contact switch, one three position on-off-on switch; One small model makers electric motor approximately 3cm x 3cm; Two telescoping pieces of fine metal tubing approximately 2mm and 4mm diameter as used by model makers ; One piece of 24 gauge nichrome wire, 25cm long; this must be straight so that it does not rub on the metal tubing sheathing it. One small coil spring.
For use, the telescopic sheath is adjusted so that approximately Scm of needle protrudes. To trap hypha! strands the needle is rotated in short bursts by moving the switch to position I and then briefly pressing the push button contact. Prolonged rotation causes the strands to become tightly wrapped around the needle and contra rotation is necessary to free them To use the needle for breaking up colonies the telescopic sheath is moved so that 6 - 7em of needle are exposed and the switch turned to the permanently on position (2) when the needle rotates rapidly and flexes giving a whisking motion.