Selective Enrichment and Isolation of Oil-Degrading Marine Bacteria from Seawater Samples

Begin with a seawater sample containing diverse microbial communities, including bacteria capable of degrading hydrocarbons.

Perform serial dilutions of the sample in saline to reduce microbial density.

Add crude oil to sterile distilled water and agitate the mixture to partially solubilize hydrocarbon components of the oil.

Allow the mixture to settle, separating it into water-soluble and water-insoluble oil fractions.

Prepare selective agar plates using each oil fraction as the sole carbon source to enrich for bacteria that degrade either soluble or hydrophobic hydrocarbons.

Plate the diluted seawater samples onto the selective media and incubate at ambient temperature.

Colonies that emerge rely on enzymes such as hydroxylases and dioxygenases to metabolize hydrocarbons.

Pick morphologically distinct colonies and restreak them onto fresh media containing the same oil fraction to obtain pure cultures of hydrocarbon-degrading bacteria.

This method enables the selective isolation of oil-degrading marine bacteria.

To prepare minimum media containing an oil-water soluble fraction and an oil-water insoluble fraction as the only carbon source, add 1-2% crude oil to 500 milliliters of sterile dis