A Potential Super Star

Pollution is one of the most significant factors reducing biodiversity in marine ecosystems. Microbial bioremediation is a natural process which can be utilised to reduce pollution levels. The Persian Gulf sits on top of the largest oil reserve in the world it is being heavily exploited which having a detrimental effect to the local marine life. Water evaporation, drilling and oil extraction are all rapidly increasing pollution in this marine ecosystem. Heavy metals and poly aromatic hydrocarbons (PAHs) are the most important pollutants in marine environments because of their persistence they can remain in marine species tissues for long periods. This study is aims were to identify a species of bacteria that has the ability to absorb copper and degrade phenanthrene.

Samples were taken from contaminated sediment in the Persian Gulf. They isolated bacteria using an enrichment method and isolated 10 marine bacteria from these sediment samples. They determined their tolerance to harmful compounds by inoculating the growth medium with phenanthrene and copper and monitoring survival success. They found one of these bacteria could tolerate high concentrations of both these compounds. It was then identified morphologically using gram staining and through a range of biochemical tests such as oxidase-catalase test and showed that the bacterium was gram negative and belongs to Pseudomonas sp. Further studies were then conducted to assess the bacterium’s suitability as a tool for bioremediation.

To monitor the biodegradation capability of the strain 500µl of cell suspension was inoculated with 100ml of phenanthrene and the decreasing concentration of phenanthrene was detected by monitoring UV absorbance at 24hr intervals over 6 days. The bacterium showed no lag phase and immediately degraded the compound by utilising it as a carbon energy source. The strain reduced phenanthrene concentration by 96.52% in 120 hours. The specialised enzyme TpbA is suggested to be responsible for this rapid biodegradation.

To monitor the biosorption capability of the strain 1ml of cell suspension was inoculated with 100ml of copper solution and the absorption of copper was monitored by measuring the remaining copper concentrations after inoculation. The copper concentration was measured at 30 min intervals by the atomic absorption spectroscopy. The bacterium was capable of reducing the copper concentration by 70.3% in just 30 minutes. The negatively charged cell wall surface and the numerous absorption sites on the bacteria are the cause of the efficient absorption.

This strain of bacteria was shown to be a very promising tool which could be effectively used in water treatment. It is clear that this strain is highly efficient at degrading phenanthrene and absorbing copper by the rapid reduction of both compounds immediately after inoculation. The rapid growth rate and natural ability of the Pseudomonas species to adapt to environmental change will also contribute to this efficacy of the strain. Problems associated with the introduction of foreign bacteria into ecosystems could potentially be less problematic as the strain originates the region that it is being used to treat; The Persian Gulf. However there is still the potential for this bacterium to be introduced to foreign contaminated marine systems if it is intelligently applied.
A review of: Safahieh, A., Abyar, H., Roostan, Z., Zolgharnein, H., Mojoodi, F. (2012). Isolation and characterization of Pseudomonas resistant to heavy metals and poly aromatics hydrocarbons (PAHs) from Persian Gulf sediments. African Journal of Biotechnology: 11(19) 4418-4423