Marine Agar

Since the marine environment is characterized by unique environmental conditions, its microflora is also unique. Marine microorganisms have the ability to survive at very low temperatures and at high salinity levels.

Both Marine Agar and Marine Broth (LC-1217) are prepared according to ZoBell, containing almost double the mineral content of sea water. The high salt content helps to simulate sea water. Bacteriological peptone provides nitrogen, vitamins, minerals and amino acids essential for growth. Yeast extract is a source of vitamins, particularly of the B-group. Bacteriological agar is the solidifying agent.

Typical formula in g/L, adjusted and/or supplemented as required to meet performance criteria.

Preparation

Suspend 55.20 grams of the medium in one liter of distilled water. Mix well and dissolve by heating with frequent agitation. Boil for one minute until complete dissolution. Sterilize in autoclave at 121 °C for 15 minutes. Cool to 50 °C, mix well and dispense into plates. It is recommended to homogenize the medium in its container before pouring into plates.

Instructions for use

Inoculate and incubate at 20-25 °C for 24-72 hours.

Using the conventional plate count technique or streaking the surface of the plate yields good results. In the spread plate technique, the agar is poured while hot and allowed to cool before inoculation. However, precaution must be taken in the pour plate method to cool the medium to 42 °C before pouring, as the majority of marine organisms are heat-sensitive.

• J. Marine Research N:42. 1941.
• Limnology and Oceanography 5:78, 1960.
• ZoBell, C.E. 1941. Studies on Marine Bacteria. I. The cultural requirements of heterotrophic aerobes. J. Mar. Res. 4:42-75.
• Buck, J.D., and R.C. Cleverdon. 1960. The spread plate as a method for the enumeration of marine bacteria. Limnol. Oceanogr.
• Weiner, R.M., A.M. Segall, and R.R. Colwell. 1985.