PLATE CULTURES

Abstract

This chapter describes the preparation of plates for streaking. When a large surface area of medium is necessary, the agar medium is allowed to solidify as a thin layer in a Petri dish. 10–15 ml of the melted sterile medium is poured into a sterile Petri-dish, care being taken to avoid contamination. The outside of the test tube or bottle should be wiped dry before pouring to avoid water droplets falling into the dish. The mouth of the flask or tube containing the medium should be flamed after removal of the cotton-wool plug and the lid of the Petri dish raised only enough to allow easy access. The chapter discusses the method for separation of mixed cultures of streak plates. The term plating is applied to the inoculation of a medium in Petri dishes, usually by successive strokes with a wire loop. A sterile wire loop is charged with the bacterial mixture or the material containing the bacteria to be isolated.