No abstract

No abstract

Recalcitrant pollutants such as polycyclic aromatic hydrocarbons (PAHs) are difficult to degrade and have been the focus for biodegradation. They form a class of pollutant on a global scale. In an attempt to contribute to the search for suitable microbial culture with potential to biodegrade low and high molecular weight PAHs, bacterial strains were isolated from engine-oil polluted sites in Lagos, Nigeria. These isolates were evaluated for possession of plasmid DNA and the role it played in PAH degradation. Out of sixteen strains isolated, two were Gram negative while the others were Gram positive isolates. They belonged to genera Micrococcus, Staphylococcus, Kurthia sp., Acinetobacter, Pseudomonas and Corynebacterium. All the isolates grew on the PAHs (anthracene, fluoranthene and pyrene) at varying rates utilizing them as sole source of carbon and energy. All the isolates also possessed plasmid DNA ranging from 17.8 to 38.9 kbp. Subjection of plasmid cured isolates to PAHs biodegradation suggest that PAHs degradation may be plasmid and/or chromosomally mediated depending on the bacterial isolate and PAHs being degraded. This study has revealed that different compounds induce varied genetic changes in bacterial isolates in response to the stimuli.

No abstract

This study investigated the level of heavy metals and poly aromatic hydrocarbon (PAH) concentrations in fresh and smoked African catfish, Clariasgariepinus from a cultured system in Lagos, Nigeria. A total of ten randomly selected life specimens of Clariasgariepinus were collected from the Marine Science Department (Aquaculture unit) University of Lagos and smoked in a 44 gallon smoking kiln for four hours. The heavy metals content was determined using FAO / SIDA, 1983 method while PAH was analyzed using gas chromatography mass spectrometry (GC MS). The results of fresh fish samples obtained were compared withnonsmoked fish samples. Heavy metals and PAHs were detected in both samples at varying concentration. However, it was observed that there was higher concentration cadmium, lead, and zinc in smoked fish though not significantly (P < 0.05) different from that in fresh fish whereas iron and copper were insignificantly (P > 0.05) higher in fresh fish. Naphthalene, fluorene, phenanthrene, anthracene, and benzo (g,h,i) perylene} were higher in the smoked fishes though Naphthalene, and anthracene were significantly (P < 0.05) higher in smoked fishes than fresh fishes. The maximum concentration of lead was 0.0492 mg/kg that is higher than the EPA safety limit (0.001 mg/kg) while 2 methylnaphthalene concentration was highest in the smoked fishes with a mean value of 4.13 mg/kg. The statistical analysis using one way ANOVA showed that there was significant (P < 0.05) differences in the heavy metals and PAH content in the fresh and smoked fish. This study suggests that smoked fish have higher concentrations of heavy metals and poly aromatic hydrocarbons which might pose a health risk to humans when consumed