K.M Ukaegbu-Obi^1,, C.C Mbakwem-Aniebo²

Analysis of the bacterial genera associated with the rhizosphere of Cyperussp., Parkiasp., Panicumpariflorium, Zea mays, Elaeisguineensis inpetroleum hydrocarbon contaminated soil in Ugada, Imo State, Nigeria was done. The study shows that densities of total culturable heterotrophic and hydrocarbon-utilizing bacteria varied with the type of plant and were higher in the contaminated rhizosphere than in the contaminated bulk soil (non- rhizosphere) of all the plants. Unlike the result of total culturable heterotrophic counts in the bulk soil, the mean counts of the hydrocarbon-utilizing bacteria were higher in the contaminated bulk soil for all plants. Elaeisguineensis, gave the lowest mean counts for both total culturable heterotrophic and hydrocarbon-utilizing bacteria of all the plants studied, this may be as a result of some of the plant’s exudates not stimulating all the bacterial community. Statistical analysis showed no significant difference (P>0.05) between the rhizosphere and bulk of total culturable heterotrophic and hydrocarbon-utilizing bacterial counts in both contaminated and uncontaminated soils. The hydrocarbon-utilizing bacterial genera isolated and identified were Acinetobacter, Arthrobacter, Alcaligenes, Bacillus, Flavobacterium, Micrococcus, Pseudomonas spp. These isolates were able to grow on petroleum hydrocarbon at different growth rates indicating that they can be used as seeds for bioaugmentation during remediation of petroleum contaminated soil.

Niger delta, rhizosphere, crude oil, hydrocarbon utilizing bacteria, potentials