Culture Media by Morphological Classification

Morphological Class

Protozoa

Culture Media

1 DNase Test Agar S. aureus produces the enzyme DNase which hydrolyses DNA. When S. aureus grows on this medium, the DNA is broken down, which can be visualised using a hydrochloric acid (HCl) solution: clear zones around the colonies indicate DNA breakdown.
2 Mannitol Salt Agar (MSA), or Chapman Agar This is a selective and differential medium. The high concentration of NaCl (~7.5%) selects for halophiles, organisms that can tolerate high salt concentrations, thereby favouring the growth of Staphylococcus species. Mannitol is the differential component: S. aureus ferments mannitol, lowering the pH of the medium, which results in a color change of the pH indicator from red to yellow. Thus, growth of S. aureus is indicated by yellow colonies.
3 Blood Agar (BA) This is a nutrient-rich, differential medium that supports the growth of many organisms. S. aureus forms colonies that are round, smooth, and golden-yellow. This bacterium typically demonstrates β-hemolysis, which is complete lysis of red blood cells, resulting in a clear zone around the colonies. This hemolysis is due to the production of hemolysins by S. aureus.
4 Sula’s Medium A liquid medium containing glycerol, asparagine, and a variety of salts. The growth of M. tuberculosis results in turbidity.
5 Proskauer and Beck’s Medium A liquid medium. The growth of M. tuberculosis causes turbidity.
6 Middlebrook 7H9 Broth This is a liquid medium that contains glycerol and Tween 80, which prevent clumping of mycobacteria. The growth of M. tuberculosis results in turbidity.
7 Dubos’ Medium A liquid medium that contains a mixture of salts, fatty acids, and polysorbate. When M. tuberculosis grows in this medium, it causes the medium to become turbid.
8 Pawlowsky Medium A potato-based medium. Growth of M. tuberculosis may be similar to that seen on the LJ Medium.
9 Loeffler Medium A serum-based medium. M. tuberculosis colonies on Loeffler medium are small, dry, wrinkled, and off-white to yellow.
10 Tarshis Medium A blood-based medium that can promote the growth of M. tuberculosis. The colonies appear similar to those on the LJ Medium.
11 Dorset Medium An egg-based medium. M. tuberculosis colonies appear similar to those on Petragnini Medium: small, round, buff-colored, and taking 3-4 weeks to develop.
12 Middlebrook 7H11 Agar This is a nutrient-rich medium similar to 7H10 but includes additional pyruvate for energy source, promoting more luxurious growth. The colonies of M. tuberculosis appear small, slightly domed, and rough with a butyrous consistency.
13 Middlebrook 7H10 Agar A selective medium that contains oleic acid, albumin, dextrose, and catalase. The colonies of M. tuberculosis appear small, rough, and buff to white-colored, taking less time to appear compared to egg-based media.
14 Petragnini Medium An egg-based medium enriched with additional nutrients to promote the growth of Mycobacterium tuberculosis. Colonies of M. tuberculosis are small, round, buff-colored, and typically take 3-4 weeks to appear.
15 Lowenstein-Jensen (LJ) Medium An egg-based medium that uses malachite green to suppress the growth of other bacteria and glycerol to stimulate the growth of Mycobacterium tuberculosis. The colonies of M. tuberculosis on LJ are non-pigmented, dry, rough, raised, irregular with a wrinkled surface, initially creamy-white, turning yellowish or buff-colored on further incubation.
16 Liquid Media (such as Nutrient Broth) E. coli exhibits homogenous turbid growth within 12-18 hours. After prolonged incubation, pellicles may form on the surface of the media.
17 Lysine Iron Agar (LIA) Used to determine the ability of an organism to decarboxylate or deaminate lysine and to form hydrogen sulfide. E. coli is typically lysine decarboxylase positive and H2S negative, so you would see a reaction of red/purple slant and purple/red butt with no black precipitate.
18 Brilliant Green Agar (BGA) A selective medium that is used to isolate Salmonella species, but E. coli can grow on it, albeit not as well.
19 Triple Sugar Iron (TSI) Agar E. coli typically produces an acid butt, acid slant, and gas, with no H2S production, indicating it ferments lactose, sucrose, and glucose.
20 m-ENDO Agar E. coli colonies appear as green with a metallic sheen, indicating lactose fermentation.
21 Eosin Methylene Blue (EMB) Agar A selective and differential medium where E. coli forms distinctive metallic green sheen colonies due to vigorous lactose fermentation.
22 MacConkey Agar (MAC) This selective and differential medium distinguishes lactose fermenters from non-fermenters. E. coli colonies are circular, moist, smooth, and pink.
23 Blood Agar (BA) E. coli colonies on this differential medium are large, circular, gray, moist, and can show β-hemolysis.
24 Nutrient Agar (NA) A non-selective medium. E. coli colonies are usually large, circular, grayish-white, moist, and smooth.
25 Nickerson’s Medium or Bismuth Sulfite Glucose Glycine Yeast (BSGG) This medium is used to stimulate the production of germ tubes, a characteristic of Candida albicans.
26 Cornmeal Agar with Tween 80 It is used for the identification of Candida species by promoting the formation of chlamydospores, which is a characteristic of Candida albicans.
27 RPMI 1640 Medium It is a rich medium that contains inorganic salts, glucose, amino acids, vitamins, and other nutrients that promote the growth of yeast cells.
28 Potato Dextrose Agar (PDA) Potato Dextrose Agar (PDA) consists of a nutrient-rich substrate, made from dehydrated Potato Infusion and Dextrose, ideal for robust mycological propagation. Agar provides the solidifying medium. Acidification, typically using sterile tartaric acid, adjusts the pH to 3.5 +/- 0.1 to create a more selective environment by inhibiting bacterial proliferation. Additionally, Chloramphenicol is incorporated as an antimicrobial agent to further suppress bacterial contamination, thereby facilitating the selective isolation of fungi.
29 Nutrient Agar It is a general-purpose medium. However, E. faecalis grows poorly on nutrient agar, which means it does not proliferate as well on this medium compared to the others listed, indicating a negative or poor growth.
30 Azide Dextrose Broth A selective medium inhibiting Gram-negative bacteria, used for the isolation of streptococci and staphylococci from mixed samples. E. faecalis will show a positive growth resulting in a turbid appearance of the broth.
31 Brain-Heart Infusion (BHI) Broth or Agar This is a nutrient-rich medium that supports the growth of a variety of fastidious organisms, including E. faecalis. The typical phenotype of E. faecalis on BHI is small, round, and white colonies.

Mycobacteria

Culture Media

1 Baird-Parker Agar (BPA) his is a selective medium for the isolation of Staphylococcus species. It has lithium chloride and glycine to inhibit the growth of Gram-negative bacteria and most Gram-positive bacteria except Staphylococcus. Egg yolk emulsion is added to detect lecithinase production and tellurite reduction. S. aureus colonies on BPA are black due to reduction of tellurite, and they exhibit a clear zone due to lecithinase activity on egg yolk.
2 Lysine Iron Agar (LIA) Used to determine the ability of an organism to decarboxylate or deaminate lysine and to form hydrogen sulfide. E. coli is typically lysine decarboxylase positive and H2S negative, so you would see a reaction of red/purple slant and purple/red butt with no black precipitate.
3 Blood Agar (BA) E. coli colonies on this differential medium are large, circular, gray, moist, and can show β-hemolysis.
4 RPMI 1640 Medium It is a rich medium that contains inorganic salts, glucose, amino acids, vitamins, and other nutrients that promote the growth of yeast cells.
5 Azide Dextrose Broth A selective medium inhibiting Gram-negative bacteria, used for the isolation of streptococci and staphylococci from mixed samples. E. faecalis will show a positive growth resulting in a turbid appearance of the broth.

Fungi

Culture Media

1 Phenol Red Mannitol Broth This is a differential medium, used to determine an organism's ability to ferment mannitol. S. aureus, which can ferment mannitol, will change the medium from red to yellow due to acid production.
2 Loeffler Medium A serum-based medium. M. tuberculosis colonies on Loeffler medium are small, dry, wrinkled, and off-white to yellow.
3 Tarshis Medium A blood-based medium that can promote the growth of M. tuberculosis. The colonies appear similar to those on the LJ Medium.
4 Dorset Medium An egg-based medium. M. tuberculosis colonies appear similar to those on Petragnini Medium: small, round, buff-colored, and taking 3-4 weeks to develop.
5 Liquid Media (such as Nutrient Broth) E. coli exhibits homogenous turbid growth within 12-18 hours. After prolonged incubation, pellicles may form on the surface of the media.
6 Brilliant Green Agar (BGA) A selective medium that is used to isolate Salmonella species, but E. coli can grow on it, albeit not as well.
7 Triple Sugar Iron (TSI) Agar E. coli typically produces an acid butt, acid slant, and gas, with no H2S production, indicating it ferments lactose, sucrose, and glucose.
8 Simmons Citrate Agar Used for citrate utilization testing. E. coli usually can't utilize citrate as a sole carbon source, so no growth or color change would be expected.
9 Cystine Lactose Electrolyte-Deficient (CLED) Agar E. coli will give lactose-positive yellow colonies.
10 Violet Red Bile Agar (VRBA) E. coli colonies are red (pink to red) and may show bluish fluorescence under UV light.
11 m-ENDO Agar E. coli colonies appear as green with a metallic sheen, indicating lactose fermentation.
12 MacConkey Agar (MAC) This selective and differential medium distinguishes lactose fermenters from non-fermenters. E. coli colonies are circular, moist, smooth, and pink.
13 Nickerson’s Medium or Bismuth Sulfite Glucose Glycine Yeast (BSGG) This medium is used to stimulate the production of germ tubes, a characteristic of Candida albicans.
14 Cornmeal Agar with Tween 80 It is used for the identification of Candida species by promoting the formation of chlamydospores, which is a characteristic of Candida albicans.
15 CHROMagar Candida This differential medium allows for the isolation and identification of Candida species based on colony color. Candida albicans usually forms green colonies on this medium.
16 MacConkey Agar Traditionally used to isolate and differentiate Gram-negative bacilli, E. faecalis can grow on this medium, producing small, round, magenta pink colonies due to lactose fermentation, indicating a positive result.
17 Todd-Hewitt Broth A liquid enrichment medium used for the cultivation of fastidious organisms such as streptococci and enterococci. E. faecalis will lead to a turbid broth due to microbial growth.
18 Enterococcosel Agar A selective and differential medium that inhibits the growth of Gram-negative bacteria and distinguishes enterococci based on their ability to grow in the presence of bile and hydrolyze esculin. E. faecalis will form small, black colonies on this medium due to esculin hydrolysis.
19 Bile Esculin Agar (BEA) A selective and differential medium that differentiates group D Streptococci and Enterococci based on the ability to hydrolyze esculin in the presence of bile. E. faecalis hydrolyzes esculin, leading to the formation of a dark brown or black precipita
20 Brain-Heart Infusion (BHI) Broth or Agar This is a nutrient-rich medium that supports the growth of a variety of fastidious organisms, including E. faecalis. The typical phenotype of E. faecalis on BHI is small, round, and white colonies.

Bacilli

Culture Media

1 DNase Test Agar S. aureus produces the enzyme DNase which hydrolyses DNA. When S. aureus grows on this medium, the DNA is broken down, which can be visualised using a hydrochloric acid (HCl) solution: clear zones around the colonies indicate DNA breakdown.
2 Middlebrook 7H9 Broth This is a liquid medium that contains glycerol and Tween 80, which prevent clumping of mycobacteria. The growth of M. tuberculosis results in turbidity.
3 Dorset Medium An egg-based medium. M. tuberculosis colonies appear similar to those on Petragnini Medium: small, round, buff-colored, and taking 3-4 weeks to develop.
4 Liquid Media (such as Nutrient Broth) E. coli exhibits homogenous turbid growth within 12-18 hours. After prolonged incubation, pellicles may form on the surface of the media.
5 Brilliant Green Agar (BGA) A selective medium that is used to isolate Salmonella species, but E. coli can grow on it, albeit not as well.
6 Triple Sugar Iron (TSI) Agar E. coli typically produces an acid butt, acid slant, and gas, with no H2S production, indicating it ferments lactose, sucrose, and glucose.
7 Simmons Citrate Agar Used for citrate utilization testing. E. coli usually can't utilize citrate as a sole carbon source, so no growth or color change would be expected.
8 Cystine Lactose Electrolyte-Deficient (CLED) Agar E. coli will give lactose-positive yellow colonies.
9 Violet Red Bile Agar (VRBA) E. coli colonies are red (pink to red) and may show bluish fluorescence under UV light.
10 m-ENDO Agar E. coli colonies appear as green with a metallic sheen, indicating lactose fermentation.
11 MacConkey Agar (MAC) This selective and differential medium distinguishes lactose fermenters from non-fermenters. E. coli colonies are circular, moist, smooth, and pink.
12 Cornmeal Agar with Tween 80 It is used for the identification of Candida species by promoting the formation of chlamydospores, which is a characteristic of Candida albicans.
13 CHROMagar Candida This differential medium allows for the isolation and identification of Candida species based on colony color. Candida albicans usually forms green colonies on this medium.
14 MacConkey Agar Traditionally used to isolate and differentiate Gram-negative bacilli, E. faecalis can grow on this medium, producing small, round, magenta pink colonies due to lactose fermentation, indicating a positive result.
15 Todd-Hewitt Broth A liquid enrichment medium used for the cultivation of fastidious organisms such as streptococci and enterococci. E. faecalis will lead to a turbid broth due to microbial growth.
16 Enterococcosel Agar A selective and differential medium that inhibits the growth of Gram-negative bacteria and distinguishes enterococci based on their ability to grow in the presence of bile and hydrolyze esculin. E. faecalis will form small, black colonies on this medium due to esculin hydrolysis.
17 Bile Esculin Agar (BEA) A selective and differential medium that differentiates group D Streptococci and Enterococci based on the ability to hydrolyze esculin in the presence of bile. E. faecalis hydrolyzes esculin, leading to the formation of a dark brown or black precipita
18 Brain-Heart Infusion (BHI) Broth or Agar This is a nutrient-rich medium that supports the growth of a variety of fastidious organisms, including E. faecalis. The typical phenotype of E. faecalis on BHI is small, round, and white colonies.

Cocci

Culture Media

1 Sf1Ep medium Culturing Treponema pallidum, the bacteria that causes syphilis, in vitro is a challenge. T. pallidum is not routinely cultured in the laboratory for diagnostic purposes, in part because it cannot be grown on artificial media. However, a breakthrough in culturing T. pallidum was reported in 2018 when researchers managed to grow the bacterium in a rabbit epithelial cell line (Sf1Ep) using a medium called 'Sf1Ep medium'. It's not used for routine diagnostic purposes, but for research only. The diagnosis involves direct microscopic examination, serologic tests, molecular tests and histopathology.
2 Mannitol Salt Agar (MSA), or Chapman Agar This is a selective and differential medium. The high concentration of NaCl (~7.5%) selects for halophiles, organisms that can tolerate high salt concentrations, thereby favouring the growth of Staphylococcus species. Mannitol is the differential component: S. aureus ferments mannitol, lowering the pH of the medium, which results in a color change of the pH indicator from red to yellow. Thus, growth of S. aureus is indicated by yellow colonies.
3 Sauton’s Medium A liquid medium that lacks detergents, which helps in the formation of corded colonies. When M. tuberculosis grows in this medium, it results in turbidity.
4 Proskauer and Beck’s Medium A liquid medium. The growth of M. tuberculosis causes turbidity.
5 Dubos’ Medium A liquid medium that contains a mixture of salts, fatty acids, and polysorbate. When M. tuberculosis grows in this medium, it causes the medium to become turbid.
6 Pawlowsky Medium A potato-based medium. Growth of M. tuberculosis may be similar to that seen on the LJ Medium.
7 Loeffler Medium A serum-based medium. M. tuberculosis colonies on Loeffler medium are small, dry, wrinkled, and off-white to yellow.
8 Tarshis Medium A blood-based medium that can promote the growth of M. tuberculosis. The colonies appear similar to those on the LJ Medium.
9 Dorset Medium An egg-based medium. M. tuberculosis colonies appear similar to those on Petragnini Medium: small, round, buff-colored, and taking 3-4 weeks to develop.
10 Lowenstein-Jensen (LJ) Medium An egg-based medium that uses malachite green to suppress the growth of other bacteria and glycerol to stimulate the growth of Mycobacterium tuberculosis. The colonies of M. tuberculosis on LJ are non-pigmented, dry, rough, raised, irregular with a wrinkled surface, initially creamy-white, turning yellowish or buff-colored on further incubation.
11 Liquid Media (such as Nutrient Broth) E. coli exhibits homogenous turbid growth within 12-18 hours. After prolonged incubation, pellicles may form on the surface of the media.
12 Lysine Iron Agar (LIA) Used to determine the ability of an organism to decarboxylate or deaminate lysine and to form hydrogen sulfide. E. coli is typically lysine decarboxylase positive and H2S negative, so you would see a reaction of red/purple slant and purple/red butt with no black precipitate.
13 Sorbitol-MacConkey agar A variant of MacConkey agar, used in detecting E. coli O157:H7, which does not ferment sorbitol, unlike most strains of E. coli.
14 Urea Agar/Broth E. coli is typically urease negative, so no color change would be expected in this medium.
15 Simmons Citrate Agar Used for citrate utilization testing. E. coli usually can't utilize citrate as a sole carbon source, so no growth or color change would be expected.
16 Tryptic Soy Agar (TSA) A general purpose medium. E. coli colonies are medium to large, with a shiny moist appearance.
17 Cystine Lactose Electrolyte-Deficient (CLED) Agar E. coli will give lactose-positive yellow colonies.
18 Mueller Hinton Agar (MHA) Typically used for antibiotic susceptibility testing. E. coli colonies appear pale straw colored.
19 MacConkey Agar (MAC) This selective and differential medium distinguishes lactose fermenters from non-fermenters. E. coli colonies are circular, moist, smooth, and pink.
20 Cornmeal Agar with Tween 80 It is used for the identification of Candida species by promoting the formation of chlamydospores, which is a characteristic of Candida albicans.
21 Nutrient Agar It is a general-purpose medium. However, E. faecalis grows poorly on nutrient agar, which means it does not proliferate as well on this medium compared to the others listed, indicating a negative or poor growth.
22 Blood Agar A differential medium used to identify bacteria based on their hemolytic properties. E. faecalis typically shows gamma-hemolysis on this medium, i.e., no hemolysis or change in the color of the medium.
23 Azide Dextrose Broth A selective medium inhibiting Gram-negative bacteria, used for the isolation of streptococci and staphylococci from mixed samples. E. faecalis will show a positive growth resulting in a turbid appearance of the broth.
24 Todd-Hewitt Broth A liquid enrichment medium used for the cultivation of fastidious organisms such as streptococci and enterococci. E. faecalis will lead to a turbid broth due to microbial growth.
25 Enterococcosel Agar A selective and differential medium that inhibits the growth of Gram-negative bacteria and distinguishes enterococci based on their ability to grow in the presence of bile and hydrolyze esculin. E. faecalis will form small, black colonies on this medium due to esculin hydrolysis.
26 Brain-Heart Infusion (BHI) Broth or Agar This is a nutrient-rich medium that supports the growth of a variety of fastidious organisms, including E. faecalis. The typical phenotype of E. faecalis on BHI is small, round, and white colonies.

Spirillum

Culture Media

1 Sf1Ep medium Culturing Treponema pallidum, the bacteria that causes syphilis, in vitro is a challenge. T. pallidum is not routinely cultured in the laboratory for diagnostic purposes, in part because it cannot be grown on artificial media. However, a breakthrough in culturing T. pallidum was reported in 2018 when researchers managed to grow the bacterium in a rabbit epithelial cell line (Sf1Ep) using a medium called 'Sf1Ep medium'. It's not used for routine diagnostic purposes, but for research only. The diagnosis involves direct microscopic examination, serologic tests, molecular tests and histopathology.
2 Mannitol Salt Agar (MSA), or Chapman Agar This is a selective and differential medium. The high concentration of NaCl (~7.5%) selects for halophiles, organisms that can tolerate high salt concentrations, thereby favouring the growth of Staphylococcus species. Mannitol is the differential component: S. aureus ferments mannitol, lowering the pH of the medium, which results in a color change of the pH indicator from red to yellow. Thus, growth of S. aureus is indicated by yellow colonies.
3 Proskauer and Beck’s Medium A liquid medium. The growth of M. tuberculosis causes turbidity.
4 Middlebrook 7H9 Broth This is a liquid medium that contains glycerol and Tween 80, which prevent clumping of mycobacteria. The growth of M. tuberculosis results in turbidity.
5 Dubos’ Medium A liquid medium that contains a mixture of salts, fatty acids, and polysorbate. When M. tuberculosis grows in this medium, it causes the medium to become turbid.
6 Pawlowsky Medium A potato-based medium. Growth of M. tuberculosis may be similar to that seen on the LJ Medium.
7 Loeffler Medium A serum-based medium. M. tuberculosis colonies on Loeffler medium are small, dry, wrinkled, and off-white to yellow.
8 Tarshis Medium A blood-based medium that can promote the growth of M. tuberculosis. The colonies appear similar to those on the LJ Medium.
9 Middlebrook 7H10 Agar A selective medium that contains oleic acid, albumin, dextrose, and catalase. The colonies of M. tuberculosis appear small, rough, and buff to white-colored, taking less time to appear compared to egg-based media.
10 Petragnini Medium An egg-based medium enriched with additional nutrients to promote the growth of Mycobacterium tuberculosis. Colonies of M. tuberculosis are small, round, buff-colored, and typically take 3-4 weeks to appear.
11 Lowenstein-Jensen (LJ) Medium An egg-based medium that uses malachite green to suppress the growth of other bacteria and glycerol to stimulate the growth of Mycobacterium tuberculosis. The colonies of M. tuberculosis on LJ are non-pigmented, dry, rough, raised, irregular with a wrinkled surface, initially creamy-white, turning yellowish or buff-colored on further incubation.
12 Sorbitol-MacConkey agar A variant of MacConkey agar, used in detecting E. coli O157:H7, which does not ferment sorbitol, unlike most strains of E. coli.
13 Urea Agar/Broth E. coli is typically urease negative, so no color change would be expected in this medium.
14 Simmons Citrate Agar Used for citrate utilization testing. E. coli usually can't utilize citrate as a sole carbon source, so no growth or color change would be expected.
15 Tryptic Soy Agar (TSA) A general purpose medium. E. coli colonies are medium to large, with a shiny moist appearance.
16 Cystine Lactose Electrolyte-Deficient (CLED) Agar E. coli will give lactose-positive yellow colonies.
17 Violet Red Bile Agar (VRBA) E. coli colonies are red (pink to red) and may show bluish fluorescence under UV light.
18 Potato Dextrose Agar (PDA) Potato Dextrose Agar (PDA) consists of a nutrient-rich substrate, made from dehydrated Potato Infusion and Dextrose, ideal for robust mycological propagation. Agar provides the solidifying medium. Acidification, typically using sterile tartaric acid, adjusts the pH to 3.5 +/- 0.1 to create a more selective environment by inhibiting bacterial proliferation. Additionally, Chloramphenicol is incorporated as an antimicrobial agent to further suppress bacterial contamination, thereby facilitating the selective isolation of fungi.
19 Todd-Hewitt Broth A liquid enrichment medium used for the cultivation of fastidious organisms such as streptococci and enterococci. E. faecalis will lead to a turbid broth due to microbial growth.
20 Enterococcosel Agar A selective and differential medium that inhibits the growth of Gram-negative bacteria and distinguishes enterococci based on their ability to grow in the presence of bile and hydrolyze esculin. E. faecalis will form small, black colonies on this medium due to esculin hydrolysis.
21 Bile Esculin Agar (BEA) A selective and differential medium that differentiates group D Streptococci and Enterococci based on the ability to hydrolyze esculin in the presence of bile. E. faecalis hydrolyzes esculin, leading to the formation of a dark brown or black precipita
22 Brain-Heart Infusion (BHI) Broth or Agar This is a nutrient-rich medium that supports the growth of a variety of fastidious organisms, including E. faecalis. The typical phenotype of E. faecalis on BHI is small, round, and white colonies.

Spirochetes

Culture Media

1 Sauton’s Medium A liquid medium that lacks detergents, which helps in the formation of corded colonies. When M. tuberculosis grows in this medium, it results in turbidity.
2 Sula’s Medium A liquid medium containing glycerol, asparagine, and a variety of salts. The growth of M. tuberculosis results in turbidity.
3 Dubos’ Medium A liquid medium that contains a mixture of salts, fatty acids, and polysorbate. When M. tuberculosis grows in this medium, it causes the medium to become turbid.
4 Pawlowsky Medium A potato-based medium. Growth of M. tuberculosis may be similar to that seen on the LJ Medium.
5 Lowenstein-Jensen (LJ) Medium An egg-based medium that uses malachite green to suppress the growth of other bacteria and glycerol to stimulate the growth of Mycobacterium tuberculosis. The colonies of M. tuberculosis on LJ are non-pigmented, dry, rough, raised, irregular with a wrinkled surface, initially creamy-white, turning yellowish or buff-colored on further incubation.
6 Sorbitol-MacConkey agar A variant of MacConkey agar, used in detecting E. coli O157:H7, which does not ferment sorbitol, unlike most strains of E. coli.
7 Urea Agar/Broth E. coli is typically urease negative, so no color change would be expected in this medium.
8 Simmons Citrate Agar Used for citrate utilization testing. E. coli usually can't utilize citrate as a sole carbon source, so no growth or color change would be expected.
9 Tryptic Soy Agar (TSA) A general purpose medium. E. coli colonies are medium to large, with a shiny moist appearance.
10 Nutrient Agar (NA) A non-selective medium. E. coli colonies are usually large, circular, grayish-white, moist, and smooth.
11 Nutrient Agar It is a general-purpose medium. However, E. faecalis grows poorly on nutrient agar, which means it does not proliferate as well on this medium compared to the others listed, indicating a negative or poor growth.
12 MacConkey Agar Traditionally used to isolate and differentiate Gram-negative bacilli, E. faecalis can grow on this medium, producing small, round, magenta pink colonies due to lactose fermentation, indicating a positive result.
13 Brain-Heart Infusion (BHI) Broth or Agar This is a nutrient-rich medium that supports the growth of a variety of fastidious organisms, including E. faecalis. The typical phenotype of E. faecalis on BHI is small, round, and white colonies.