Microbiology lab exam 2 2025 Questions & Answers with 100% Correct Answers | Verified

gram-positive - appear purple gram-negative - appear pink Isolation by Dilution - -reducing number of bacteria so that individual colonies may be isolated -streak plate technique is commonly used to separate mixed cultures to isolate colonies that can be used to make a pure culture Selective media - promotes the growth of some organisms and inhibits the growth of others Differential media - show different growth characteristics for certain organisms, such as a color change TSA - Tryptic Soy Agar -neither selective nor differential MSA - Mannitol Salt Agar -both selective and differential -selects for salt tolerant (halophiles) -differential- mannitol fermenters change media from red to yellow EMB - Eosin Methylene Blue Agar -both selective and differential -selects for gram-negative and inhibits gram-positive -differential- lactose fermenters exhibit metallic green sheen Carbohydrate Catabolism labs - Starch hydrolysis and OF glucose deeps