Spreading microorganisms on cultivating gel in Petri dish - in continuous movement uninterrupted by sterilising spreader

摘要

Laboratory technique and appts. for spreading a prod. contg. microorganisms on the surface of a cultivation gel, partic. in a petri dish. The spreading is carried out without raising the spreader from the surface from start to finish of the operation. The spreader drains out the prod. in several lines of which at least adjacent pairs cross each other. At each intersection, the quantity of prod. drawn onwards by the spreader is progressively decreased. The spreader is pref. a flat plate of rigid material, e.g. plastic or metal, with a line of teeth on the underside to draw out the prod. from a single deposit on the surface of the gel. The teeth pref. lie on a straight line set at an angle between the direction of longitudinal displacement of the spreader and the perpendicular to that direction. The spreader is advanced longitudinally with simultaneous reciprocation at right angles to the direction of advancement, giving the teeth zig-zag tracks across the gel surface. Used for thinning out and sepg. a prod. contg. microorgansis on the surface of a nutrient gel in a petri dish. Spreading is carried out in a single, uninterrupted movement of a spreader which does not have to be removed, sterilised and cooled between spreading successive sets of intersecting line. This is quicker than previous techniques.