The rhizosphere and non rhizosphere soil of three plants namely, Eucalyptus camaldulensis, Lablab purpeureus and Moringa oleifera were sampled for the presence of heterotrophic bacteria (HB) and hydrocarbon utilizing bacteria (HUB). Counts for both rhizosphere and non rhizosphere soils of the plants were compared. The rhizosphere soil of M. oleifera had the highest mean counts (31.4 x 108 cfu/g) of HB followed by Lablab purpeupreus (27.0 x 108 cfu/g) and E. camaldulensis with (22.8 x 108 cfu/g). The non-rhizosphere of E. camaldulensis had the highest HB counts of 40.4 x 108 cfu/g while the least count was obtained for L. purpeureus (5.0 x 108cfu/g). Statistical analysis of the data showed no significant difference (P> 0.05). The rhizosphere soil counts for HUB for Moringa oleifera ranged from 9.0 x 104 to 4.0 x 105cfu/g, while counts for Lablab purpeureus ranged from 1.6 to 2.1 x 105 cfu/g. Eucalyptus camaldulensis had HUB of 3.0 - 4.2 x 105cfu/g. The least HUB count for non-rhizosphere soil was observed in L. purpeureus (1.9 x 105 cfu/g) while the highest count was observed in M.oleifera (4.2 x 105 cfu/g). Hydrocarbon degraders were identified as Kleibsiella pneumoniae, Lactobacillus casei, Enterococcus gallinerium, Cedecea neteri, Actinomyces viscosus, Gardnarella sp, Erisipelothrix rhusiopathae, Corynebacterium ovis, Corynebacterium hofmanii, Aeromonas sp, Brochothrix campestris and Listeria murrayi. Most of the isolates grew well on hydrocarbons except Listeria murrayi. The results suggests that the organisms can serve as seeds for bio-augmentation during remediation of polluted environment besides the plants may be used in rehabilitation of oil polluted soil.

Keywords: Bacteria, Biodegradation, Hydrocarbon, Phytoremediation, Rhizosphere.