MCB 2610 Study Guide - Quiz Guide: Methylene Blue, Swan Lake, Eosin
Document Summary
Investigating environmental samples: water testing exercise, did either of the water sources contain coliforms? (1 pt) if yes which one and how was this determined? (1 pt) Swan lake water source contain coliforms and this was determined by adding a sample from the water source into (lauryl tryptose) lt broth and streaking it onto eosin methylene blue (emb) media. The media used is eosin methylene blue media and it is selective and differential. Eosin methylene blue is the dye that selects for gram negative organisms. The media is also differential for lactose fermentation which causes a color change: why do you think your water source tested positive for coliforms (comment on the environmental conditions that may be conducive to such organisms)? (2 pt) The water tested positive for coliforms because the lake was most likely contaminated with pathogens from animal feces and other sources because if pathogens are present that means coliforms are also always present.
