Generic Composition and Degradation Activity of Hydrocarbon-Degrading Bacteria Isolated from the Open Sea

Abstract

Generic composition and degradation activity of hydrocarbon-degrading bacteria in pelagic seawater were studied. Eighty six strains of hydrocarbon-degrading bacteria were isolated from seawater of the Western North Pacific Ocean, Eastern Indian Ocean and South China Sea.
n-Tetradecane (n-C₁₄) degradation rate (n-C₁₄ 20 μl/10ml medium) at 20°C for 14 days was under 25% for about half the number (42 strains) of the isolated bacteria. Bacterial strains in which the n-C₁₄ degradation rate was over 50%, were only 12% (10 strains) of the isolates.
The generic composition was determined for 41 isolates among the 86 strains. Bacterial family and genera of identified strains were Pseudomonas (54%), Alcaligenes (22%), Acinetobacter-Moraxella (10%), Flavobacterium (10%) and Vibrionaceae (5%). The members of genus Pseudomonas were predominant among the hydrocarbon-degrading bacteria distributed in the regions studied. There was no distinct difference in n-C₁₄ degradation rate among the bacterial genera.
The present study showed that hydrocarbon-degrading bacteria of various genera were widely distributed in pelagic areas. It is thus suggested that they play the main role in the process of natural self-purification of the seawater from hydrocarbons in these environments.