A streaker device for streaking a microbial inoculum for single colonies on the surface of a solid growth medium. The streaking device has a row of spaced apart contact surfaces for contact with the surface of the solid growth medium. The spaced apart contact surfaces are resiliently flexibly supported by a common support member so as to accommodate variations in depth of growth medium. The spaced apart contact surfaces may be provided on lowermost part of axially curved portions of plastics straps, that are angled backwardly. It is found that formation of a single band can give separation into single colonies. Also provided is an automatic streaking apparatus.