test and result identification

EMB

EMB

no growth — gram positive

EMB

growth — gram negative

green — strong lactose fermenter

EMB

growth — gram negative

purple/ pink — weaker lactose fermenter

EMB

growth — gram negative

white/gray — non-lactose fermenter

macconkey

both sides have growth — both sides gram negative

left = pink — lactose fermenter

right = yellow — non-lactose fermenter

PEA

no growth — gram negative

thioglycollate broth

phenol red + sugar

MSA

bottom = no growth — gram negative

left = growth, pink/red — gram positive/ halophile, non-mannitol fermenter (staph. aureus)

right = growth, yellow — gram negative, mannitol fermenter (staph. epidermitis)

nitrate reductase test

tryptone broth

left = red ring — tryptophanase/ indole positive

right = yellow ring — tryptophanase/ indole negative

SIM

phenylalanine slant

left = green — phenylalanine deaminase positive

right = yellow — phenylalanine deaminase negative

simmon’s citrate

left = blue — able to use citrate/ citrase positive

right = green — not able to use citrate/ citrase negative

urease test

left = pink — urease positive

right = yellow — urease negative

voges-proskauer

left = red — positive

right = no color change — negative

methyl red

left = red — positive

right = yellow — negative

TSI agar

spirit blue

left = no clearing — lipase negative

right = clearing — lipase positive

litmus milk

peptone iron agar

black precipitate — H₂S positive

lysine decarboxylase

purple — positive

DNAse

no clearing — DNAse negative

starch agar

all dark brown — alpha-amylase negative