Enumeration of Total Heterotrophic and Petroleum-degrading Bacteria Counts in Water and Sediments from Diobu Creek, Port Harcourt, Nigeria

Abstract

Introduction: Bacteria play a significant role in the biochemical cycling of nitrogen, carbon, sulphur, and oxygen in aquatic environments. Hydrocarbons are released naturally from oil seeps and incidental discharges which represents a significant source of pollution. Estuarine systems are particularly susceptible to anthropogenic hydrocarbon contamination. Although oil contaminants are weathered by photo-oxidation and evaporation complete degradation is dependent on the metabolic activities of the microbial population inherent to the area. Aim: This work aims to determine the total heterotrophic bacterial counts (THBCs) and petroleum-degrading bacteria counts (PDBCs) in water and sediment from Diobu creek. Methodology: The THB and PDB in water and sediments from a polluted creek (Diobu Creek) were determined by serial dilution and plating on nutrient agar and petroleum-degrading bacteria agar and the isolated bacteria were identified. Results: The THBCs in water were from 6.3 x 103 CFU/mL and 6.33 x103 CFU/mL, the highest THBCs were recorded in June (wet season). The THBCs in sediments was from 1.7 x 106 CFU/g to 1.85 x106 CFU/g. The highest THBCs were recorded in the month of June. The PDBCs in water was from 0.2 x 103 CFU/mL and 3.9 x103 CFU/mL, whereas the PDBCs in sediments ranged from 3.4 x106 to 9.5 x 106 CFU/g, high counts were obtained if sampling were carried out in rain or after rain. The bacteria isolated were Bacillus sp, Pseudomonas sp., Corynebacterium sp., Acenetobacter sp., Alkaligenes sp., Escherichia coli, Micrococcus, Klebsiella sp. and Flavobacterium sp. Conclusions: The increased counts of PDBs in aquatic environments might be stimulated by the presence of pollutant hydrocarbons or chemicals discharged into the creek which was degradable by bacteria. The activity of PDBs in detoxifying polluted environments is the most eco-friendly.