Analysis of bacterial contamination

Using an aseptic technique remove a sample of spent medium and sediment it at 20,000 g for 20 min. 

A loop of the sediment should be spread on a blood agar plate (Appendix 4) and incubated at 37°C for 2-7 days when most bacterial contamination will show up. 

Samples should be smeared onto glass slides and air-dried prior to staining with Gram stain or methylene blue (Appendix 2). 

---