Abstract
Among luminescent organisms, bacteria are most abundant, inhabiting oceans as free livings or as symbionts on the
surface or inside larger marine organisms. The phenomenon of bioluminescence is well regulated and requires growth
medium supplemented with various organic and inorganic salts for persistent luminescence.
To study the effects of various salts like Calcium Chloride, Magnesium Sulphate and sodium Chloride on growth and
luminescence, vibrio harveyi strain DGU300 (GenBank Accession No. KY653092) was cultured under various growth
conditions. Luminescence was significantly reduced in medium deficient in essential inorganic compounds. When
cultured in enriched medium, considerable luminescence was recorded even when the cells were in stationary phase.
However when the strain was cultured in ASW (Artificial Sea Water) + 1 % glycerol lacking in any of the selected
organic compounds displayed no luminescence even in log phase, suggesting these compounds should be an integral
part of the media for culturing luminescent bacteria.
