Nutrient agar is a general purpose medium supporting growth of a wide range of non-fastidious organisms. It typically contains (mass/volume)

• 0.5% peptone – this provides organic nitrogen
• 0.3% beef extract/yeast extract – the water-soluble content of these contribute vitamins, carbohydrates, nitrogen, and salts
• 1.5% agar – this gives the mixture solidity
• 0.5% sodium chloride – this gives the mixture proportions similar to those found in the cytoplasm of most organisms
• distilled water – water serves as a transport medium for the agar’s various substances
• pH adjusted to neutral (6.8) at 25 °C (77 °F).

These ingredients are combined and boiled for approximately one minute to ensure they are mixed and then sterilized by autoclaving, typically at 121 °C (250 °F) for 15 minutes. Then they are cooled to around 50 °C (122 °F) and poured into Petri dishes which are covered immediately. Once the dishes hold solidified agar, they are stored upside down and are often refrigerated until used. Inoculation takes place on warm dishes rather than cool ones: if refrigerated for storage, the dishes must be rewarmed to room temperature prior to inoculation.

Mueller–Hinton agar is a microbiological growth medium that is commonly used for antibiotic susceptibility testing, specifically disk diffusion tests. It is also used to isolate and maintain Neisseria and Moraxella species.

It typically contains:

• 2.0 g beef extract
• 17.5 g casein hydrolysate
• 1.5 g starch
• 17.0 g agar
• 1 liter of distilled water.
• pH adjusted to neutral at 25 °C

Five percent sheep’s blood and nicotinamide adenine dinucleotide may also be added when susceptibility testing is done on Streptococcus and Campylobacter species.

It has a few properties that make it excellent for antibiotic use. First of all, it is a nonselective, nondifferential medium. This means that almost all organisms plated on it will grow. Additionally, it contains starch. Starch is known to absorb toxins released from bacteria, so that they cannot interfere with the antibiotics. Second, it is a loose agar. This allows for better diffusion of the antibiotics than most other plates. A better diffusion leads to a truer zone of inhibition.

Mueller–Hinton agar was co-developed by a microbiologist John Howard Mueller and a veterinary scientist Jane Hinton at Harvard University as a culture for gonococcus and meningococcus. They co-published the method in 1941

Mueller–Hinton agar is a microbiological growth medium that is commonly used for antibiotic susceptibility testing, specifically disk diffusion tests. It is also used to isolate and maintain Neisseria and Moraxella species.

It typically contains:

• 2.0 g beef extract
• 17.5 g casein hydrolysate
• 1.5 g starch
• 17.0 g agar
• 1 liter of distilled water.
• pH adjusted to neutral at 25 °C

Five percent sheep’s blood and nicotinamide adenine dinucleotide may also be added when susceptibility testing is done on Streptococcus and Campylobacter species.

It has a few properties that make it excellent for antibiotic use. First of all, it is a nonselective, nondifferential medium. This means that almost all organisms plated on it will grow. Additionally, it contains starch. Starch is known to absorb toxins released from bacteria, so that they cannot interfere with the antibiotics. Second, it is a loose agar. This allows for better diffusion of the antibiotics than most other plates. A better diffusion leads to a truer zone of inhibition.

Mueller–Hinton agar was co-developed by a microbiologist John Howard Mueller and a veterinary scientist Jane Hinton at Harvard University as a culture for gonococcus and meningococcus. They co-published the method in 1941