Microorganisms in an aquatic environment may occur at all depths ranging from the surface region to the very bottom of the ocean trenches. The top layers and the bottom sediments harbour higher concentration of microorganisms (1). Marine microorganisms are vital to ecological cycles because they form the foundations of many food chains (2). Zobell Marine Agar formulated by Zobell (3), has a composition that mimics seawater (4) and thus helps the marine bacteria to grow abundantly. This medium has been used for the growth of marine bacteria (5, 6).
Zobell Marine Agar 2216 contains the nutrients, which are required for the growth of marine bacteria.These media have minerals as in seawater (7) and peptic digest of animal tissue and yeast extract as the sources of nutrients for the marine bacteria as reported by Jones (8). High amount of salt content is used to simulate seawater. Other minerals are used to mimic the mineral composition of seawater.
Pour plate and spread plate techniques can be used for enumeration. In the pour plate technique, the agar must be cooled to 42°C before inoculation to support thermo-sensitive nature of most marine bacteria. In spread plate technique, the medium is poured while still hot and allowed to cool and solidify before inoculation.
Directions: Suspend 55.25 grams in 1000 ml distilled water. Heat to boiling to dissolve the medium completely. Sterilize by autoclaving at 15 lbs pressure (121°C) for 15 minutes. Mix well and Pour in sterile Petri plates.