• GM- rods
• Facultative anaerobic
• Inhabit the large intestine of the gasterointestinal tract

Lactose fermentation.

• Eosin-methylene blue agar.
• Differentiates based on lactose fermentation
  • Colored colonies (pink or metalic green) ferment lactose
  • Colorless do not ferment lactose.
• Selects for gram negative - EMB inhibits GM+ growth.

• Triple Sugar Iron (TSI) agar.
• Prepared on slant - inoculated by streaking and then stabbing.
• Contains glucose, lactose, sucrose, ferrous sulfate, phenol red and nutrient agar.

• Yellow is acid, Red is alkaline. 
• R/Y - Ferments glucose only.
  • Glucose is consumed and amino acids acids are used for energy which oxidize change pH.
• Y/Y - Ferments glucose, lactose, and/or sucrose
• R/R - does not ferment any sugar (double check for growth)
• (G) Bubbles and cracks - CO₂ gas production.
• Black precipitate - H2S is produced.
  • H₂S reacts with ferrous sulfate which makes black precipitate.

• Gm+ cocci
• Catalase - negative
• Example - Enterococcus faecalis

• Selective for GM-
• Differential for lactose fermenation.

• Differential for sugar fermentation.
• Enrichment because of nutrients added to agar.