COMPARATIVE ASSESSMENT OF ENRICHMENT MEDIA FOR ISOLATION OF PYRENE-DEGRADING BACTERIA

This study suggests an effective enrichment technique for the isolation of high molecular weight polyaromatic hydrocarbons HMW PAHs-degrading organisms. Five enrichment media (En-media) containing different substrates; diesel, naphthalene (Nap), anthracene (Ant) and/or pyrene (Pyr) were compared for isolation of pyrene-degrading bacteria (PDB) from an oily sludge contaminated soil. This showed that different En- media led to significantly increased numbers of PDB over those recovered from the original soil sample (P = 0.0077). A multiple comparison test of means was performed between individual En-media, revealed a statistically significant difference between; (i) Pyr and (Pyr + Nap + Ant) En-media, (ii) (Pyr + diesel) and (Pyr + Nap) En-media, (iii) (Pyr + diesel) and (Pyr + Ant) En-media, and (iv) (Pyr + diesel) and (Pyr + Nap + Ant) En-media. Results showed that enrichment with (Pyr + diesel) was the most successful method for the growth of Pyr-degraders, followed by other En-media in the following decreasing order: Pyr > (Pyr + Nap) > (Pyr + Ant) > and (Pyr + Nap + Ant). Three organisms were identified for their ability to degrade Pyr, and may be considered as inoculants for application in ioremediation of contaminated soil.