Appearance of colonies microorganism Essay Example for Free

Appearance of colonies microorganism raiseVRBAAppearance of Colonies Microorganisms Red, surrounded by reddish precipitation zones, diameter1- 2 mm Lactose- positive degree Enterobacteriaceae coliform bacteria, E. coli Pink, pin-point colonies Enterococci, possibly Klebsiella dull Lactose-negative Enterobacteriaceae CCAE. coli dark-blue to violet colonies (Salmon-GAL and X-glucuronide reaction).Total coliforms salmon to red colonies (Salmon-GAL reaction) and dark-blue to violet colonies (E. coli).Other Gram-negatives colourless colonies, except for some organisms which possess -D-glucuronidase activity. These colonies appear light-blue to turquoise.In order to confirm E. coli, coat the dark-blue to violet colonies with a drop of KOVACS indole reagent. If the reagent turns to a cherry-red color after some seconds, a positive indole formation confirms the presence of E. coli.E. coli in Macconkey AgarMACCONKEY AGARAppearance of Colonies Microorganisms Colorless, translucent Salmonella, Shigella, others Large,red, surrounded by ambiguous zones Escherichia coli Large, pink, mucoid Enterobecter, Klebsiella Very small, opaque, isolated colonies Enterococci, Staphylococci, and others picpicS. aureus in baird-parker agarBAIRD-PARKER AGARAppearance of colonies Microorganisms Black, shiny, convex colonies 1-5 m in diameter with a narrow, white edge surrounded by a clear zone 2-5 mm Staphylococcus aureus wide. Opaque rings within the clear zones only appear after 48 hours of incubation Black, shiny, irregular shape. Opaque zone develop around the colonies after 24 hours. Staphylococcus epidermidis Growth sometimes Very small, brown to black, no clear zones. Micrococci Dark brown, dull, clear zones sometimes appear after 48 hours. Bacillus species White, no clear zones. Yeasts picP. aeruginosa in cetrimide agarpicpicSalmonella in Macconkey Agarpic