A review of: Papa, R., Parrilli, E. & Sannia, G. (2009). Engineered marine Antarctic bacterium Pseudoalteromonas haloplanktis TAC125 : a promising micro-organism for the bioremediation of aromatic compounds. Journal of Applied Microbiology 106, 49-56.
The application of chemical compounds is a common feature of anthropogenic industrial and agricultural advancement. This has led to numerous environmental contamination events which can negatively impact global biodiversity and human health. Firmer regulations have been applied by many countries in an attempt to control these incidents; however a considerable international risk threatening the marine environment remains (e.g. oil spills). Research outlines bioremediation as an environmentally sensitive and economically viable practice in decontaminating polluted environments, by removing pollutants and promoting the restoration of a contaminated site.
Bioremediation is a natural process involving the growth of indigenous hydrocarbon degraders. It can be accelerated in response to a contamination event, by the application of specific techniques such as bioaugmentation or biostimulation. An important feature of these processes is the microbial degradation of aromatic hydrocarbons which has been a popular area of investigation, in order to refine clean up methods. The authors of this paper aim to investigate the possible degradative capabilities of the psychrophilic bacterium, Pseudoalteromonas haloplanktis TAC125, by examining the rate of degradation of aromatic compounds at low temperatures.
The recombinant Antarctic bacterium P. haloplanktis TAC125 is engineered from the mesophilic bacterium Pseudomonas sp. OX1 to encourage the recombinant aromatic oxidative activity encoded by the enzyme Monooxygenase toluene-o-xylene (ToMO). The ToMO enzyme can convert various aromatics (e.g. phenols, cresols, dimethylphenols as well as nonhydroxylated molecules such as toluene and o-xylene) into corresponding catechols in a wide range of temperatures. During in silico genome analysis of P. haloplanktis TAC125, DNA sequence coding for a putative protein similar to laccase was discovered. Bacterial laccases are broadly assimilated with the oxidation of dioxygenated aromatic compounds such as catechols, and are useful biocatalysts in various biotechnological applications.
The study analysed the catabolic features characterised by recombinant ToMO activity and endogenous laccase enzymatic activity of the engineered bacterium P. haloplanktis TAC125. Additional analysis included its capability to grow on aromatic compounds which were controlled as its only carbon and energy source.
Results suggest that cells of P. haloplanktis TAC125 expressing recombinant ToMO enzymatic activity could potentially influence bioremediation by improving degradative capabilities. However, P. haloplanktis TAC125 must be stably engineered to consistently maintain ToMO expression by using an insertional mutation strategy. Subsequently, the employment of this engineered Antarctic bacterium and other psychrophilic bacteria is advocated in the bioremediation of chemically contaminated marine environments and cold industrial effluents.
Recent research has been directed at methods regarding the genetic manipulation of mesophilic bacteria to create or improve an ability to degrade various pollutants. This study involving P. haloplanktis TAC125 offers additional support for the utilisation of engineered bacteria in bioremediation by demonstrating the feasibility of isolating a bacterium from an unpolluted environment and enhancing its degradative capability. This is suggested to be achieved by inducing the development of innovative and specific traits of the bacterium and altering it to grow on single aromatic compounds (e.g. phenol) as a sole carbon and energy source.
I think this paper draws an interesting conclusion into the genetic manipulation and application of microbial life in ecological management. Techniques involving the isolation and transformation of a species native to a specific environment, and applying it in another location, will inevitably induce a debate surrounding ethical issues. Information of the potential impact of application (e.g. weathering effects) should be considered in order to establish whether these methods should be broadly applied or only utilised in certain conditions. Therefore additional testing and research ought to be conducted before concluding the robust viability of this approach. Nevertheless, it could be a useful addition to current decontamination methods in enhancing the treatment of a contaminated site in the marine environment.
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