Department of Microbiology, University of Uyo, P.M.B.1017,Uyo, Nigeria; Department of Chemistry, University of Uyo, P.M.B.1017, Uyo, Nigeria; Ministry of Health, Damaturu, Yobe State, Nigeria
Eduok, S.I., Department of Microbiology, University of Uyo, P.M.B.1017,Uyo, Nigeria; Ita, B.N., Department of Chemistry, University of Uyo, P.M.B.1017, Uyo, Nigeria; Uye, U.O., Ministry of Health, Damaturu, Yobe State, Nigeria; Utuk, N.M., Department of Microbiology, University of Uyo, P.M.B.1017,Uyo, Nigeria
Polycyclic aromatic hydrocarbon (PAH)-utilizing bacterial density and content in the rhizosphere, phyllosphere and sediment from Qua Iboe River estuary (QIRE) were analyzed using standard microbiological and chemical techniques. The heterotrophic (HET) bacterial counts ranged from 92/0.54 to 142/0.62cfu/m2, 12.5×105 to 13.2×105 cfu/g and 10.6×105 to 12.1×105cfu/g; Hydrocarbon-utilizing bacterial (HUB) count ranged from 74/0.58 to 82/0.62cfu/m2, 9.4×105 to 10.9×105 cfu/g, and 7.6×105 to 9.2×105 cfu/g, polycyclic aromatic hydrocarbon-utilizing bacterial (PAHUB) count ranged from 45/0.56 to 52/0.62cfu/m2, 7.9×105 to 11.9×105 cfu/g and 7.1×105 to 9.7×105 cfu/g, total Vibrio count (TVC) ranged from 00/0.56 to 21/0.60cfu/m2, 5.8×105 to 7.9×105 and 4.7×105 to 7.4×105cfu/g for the phyllosphere, rhizosphere and sediment samples respectively. There was a moderate to very high positive correlation (r = 0.69, 0.97 and 0.97, p = 0.05) in the microbial counts of the sediment and rhizosphere from locations 1, 2 and 3 respectively. Predominant culturable bacterial isolates were Vibrio alginolyticus, V. estuarianus, Alcaligenes denitrificans, Pseudomonas aeruginosa, P. putida, Chromobacterium violaceum, Nocardia sp, Micrococcus varians, Acinetobacter iwoffii, Serratia marcescens, Bacillus subtilis, Chromatium sp, Escherichia coli, Anabaena, Enterobacter aerogenes, Sarcina sp, Flavobacterium breve, Nodularia and Erwinia amylovora. Total PAH concentration ranged from 7.26 to 7.51mg/kg (rhizosphere), 8.92 to 9.55mg/kg (sediment), 9.92 to 11.13mg/kg (mangrove root) and 18.65 to 25.21mg/kg (phyllosphere). The bioaccumulation factor (BAF) for phenanthrene, pyrene, benzo(a)anthracene, chrysene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, dibenzo(a,h)anthracene and benzo(g,h,l)perylene were above 1, an indication that biomagnification of carcinogenic PAH could be occurring along the food chain. The bacterial isolates exhibited varying rate of PAH utilization, strongly suggesting possession of relevant genomic properties and degradative enzymes, although pre-exposure to the pollutants in the natural environment could have been an influencing factor. R. racemosa as keystone specie in the QIRE with its associated microbes could be used in phytoremediation and as indicator of exposure for retroactive risk assessment of ambient air and sediment contamination with PAH in estuarine ecosystem. © Research India Publications.