Five heavy metals tolerant bacteria were isolated from petroleum refinery effluent and identified as Pseudomonas aeruginosa, Staphylococcus aureus, E. coli, Proteus vulgaris and Klebsiella pneumoniae. Each isolate was inoculated into different concentrations of cadmium, chromium, nickel and zinc to determine its maximum tolerance for each heavy metal. All five isolates had low maximum tolerance concentration for cadmium (0.9 mg/L) when compared to chromium (5 mg/L), nickel (5 mg/L) and zinc (7 mg/L). Mixed culture consortium (MCC) remediated high percentage of cadmium (100%), chromium (33.4%), nickel (73.9%), and zinc (90.1%) from the petroleum refinery effluent than pure culture isolates. Among the pure culture isolates Pseudomonas aeruginosa (Cd (100%), Cr (23.1%), Ni (64.3%) & Zn (53.9%) yielded high values for the reduction of heavy metals in the refinery effluent when compared to Staphylococcus aureus, E.coli, Proteus vulgaris and Klebsiella pneumoniae. The isolated bacteria were effective for the remediation of heavy metals from petroleum refinery effluent.

Abstract:Clostridium acetobutylicum ATCC 824 is a solventogenic, obligate anaerobic bacterium that can grow on various types of carbohydrates and are capable of producing spores. In the present study, Clostridium acetobutylicum was successfully grown on TYA medium (tryptone, yeast, acetate medium) containing two different carbon sources, glucose and sucrose coupled with the production of acids (butyric and acetic acid) and solvents, ABE (acetone, butanol and ethanol). An investigation was undertaken to determine the impact of the two types of carbon sources on the solvent production and growth of Clostridium acetobutylicum. HPLC and GC analysis revealed the amount of acids and solvents produced respectively, as well as the amount of unutilized sugars. The amount of combined ABE produced on glucose (0.19g/l A, 0.39g/l B, 0.06g/l E) was higher than on sucrose as carbon source (0.15g/l A, 0.30g/l B, 0.03g/l E). The colony forming units of Clostridium acetobutylicum grown on glucose (4.70 x 10 5 units/ml) was higher than on sucrose (0.1 x 10 5 ) as judged by dilution spread plating on agar. Hence, Glucose was confirmed as the carbon source characterized by the best performance for solvents production and growth of the bacterium. The whole production process on both glucose and sucrose was observed to mainly influence the production of butanol with the concentration of 0.39g/l and 0.30g/l respectively, over the production of other solvents. Higher amount of solvents was produced at lower pH in both cultures with the different carbon sources. Wet-mounts, gram stain and endospore stain were used to determine the motility, type and sporulation of Clostridium acetobutylicum respectively. Acidogenic phase which seems to couple with the growth of vegetative cells, results into production of acetic and butyric acids. Solventogenic phase commences with a drop in pH and is accompanied by the onset of sporulation.

Environmental pollution is principally caused by human activities that usually result in the release of man-made pollutants such as biological, chemical and radioactive in such states as solid, liquid and gaseous substances into the biosphere via, land, water and air. Globally, the increasing rate of environmental contamination by ammunition/explosives resulting from their increasing deployments in the rising spites of military conflicts and training has certainly become a matter of great concern for every nation. The aim of this research was to molecularly characterize some isolated bacteria from an apparent munitions contaminated sites in Kachia Military Firing Range, Kaduna State. DNA from each isolated bacteria was extracted and 16s rRNA Gene amplified from each isolated bacteria DNA using thermo cycler. The amplified genes were run on Agarose gel plate and visualized. Amplified gene bands were sequenced and Basic Local Alignment Search Tool (BLAST). 16s rRNA gene sequences result aligned with BLAST search of NCBI databases that revealed the presence of Lysinibacillus pakistanensis, Eschericia coli, Achromobacter spanius, Achromobacter animicus, Escherichia fergusonii and Shigella sp. The results identified bacteria that were isolated from munitions contaminated sites and that could also be useful for their bioremediation potential against munitions contaminant.