Fig. 1.

A The four-quadrant streak plate method. (a) Sample on the plate. (b) With the loop, streaking quadrant 1 and 2. (c) Streaking quadrant 3. (d) Streaking quadrant 4. B Schematic representation of plates and mode of quotation used for semi-quantitative counting of bacteria (very rare colonies = very low density; rare colonies = low density; some colonies = medium density; numerous colonies = high density; very numerous colonies = high density)