Post Deepwater Horizon oil rig explosion, debates included the use of bioremediation as a waste management technique to clear up any unwanted hydrocarbons released from oil spills. Microbial activity in oil spills is a naturally occurring phenomenon, which includes hydrocarbon degrading bacteria. However, this is a slow process which cannot eliminate the contaminants before their toxins effect the surrounding environment. Bioremediation is used in this context to stimulate the growth of hydrocarbon degrading microbes, which use hydrocarbons as a source of energy and break them down into non-toxic components.
Bioremediation has previously been used to control catastrophic effects of petroleum however, Ron and Rosenberg (2014) believe that there is still scope to improve the method used. Whilst previous studies concentrate on naming microorganisms found in oil spill sites, Ron and Rosenberg are more interested in optimizing the in situ conditions for rapid microbial growth. They experimentally demonstrate a methodology for accelerating the degradation of hydrocarbons in the sea for the first time and explain each step of bioremediation and their recommended improvements:
First of all appropriate oil-degrading bacteria had to be found. Cycloclasticus strains were selected due to their abundance in previous oil spills and their ability of degrading the toxic polycyclic aromatic hydrocarbons.
Second physical interaction between bacteria and water-insoluble hydrocarbons need to be enhanced, wherefore two biological methods such as adhesion mechanisms and emulsification of the hydrocarbon are suggested.
Third, the nutritional requirements for the growth of hydrocarbon-degrading bacteria must be met. At that point Ron and Rosenberg`s strategy really differs from previous strategies in bioremediation. Next to the hydrocarbons, bacteria need other resources, such as nitrogen and phosphorus, which are limited in the sea, to increase growth. Properties such as water solubility, cost and side effects make many fertilizers unsuitable and have been unsuccessful in the past. Ron & Rosenberg tested Uric acid, the major nitrogen waste product of birds in a simulated open system and found that bacterial growth was massively improved and 70% of the oil contaminant was degraded. Uric acid, which is naturally occurring and cost efficient, therefore can be used as a natural fertilizer.
The way of analysing previous methods and explaining problems of bioremediation present during oil spillages, was easy to follow. Problems in the past has shown the importance of testing methods for such big intervention with the environment, experimentally beforehand. Nevertheless, it is understandable that predicting environmental impacts of enhanced microbial activity is difficult and decisions in critical situations have to be made urgently. Although the perfect solution may never be found, bioremediation may be improved in the future, by testing effects of bioremediation on a large scale and over a long period of time.
Anyway, bioremediation is a great way of helping to clean up our oceans and next to oil spillages it might be useful to reduce the increasing amount of marine micro-plastics in the sea.
Reference: Ron, E. Z. and Rosenberg, E. (2014) Enhanced bioremediation of oil spills in the sea. Current Opinion in Biotechnology, 27: 191-194.
http://www.sciencedirect.com/science/article/pii/S0958166914000354
This is an interesting idea from two scientists who have a very long and distinguished history of applications in marine/ environmental microbiology. In the past, guano was widely used as a fertilizer in agriculture, but I believe it was over-exploited and there are big environmental problems with mining it. Do the authors say anything about the amounts required to clean up a big oil spill and how easy it would be to use these amounts?
ReplyDeleteHi Colin,
DeleteRon and Rosenberg did not use many numbers in paper. They suggested uric acid as it is the "major component of inexpensive and commercially available guano fertilizer". It kind of sounds as if they don`t actually have looked into how much the actual costs in case of a big oil spill would be, there is also nothing mentioned about the amounts required. I think their approach on testing fertilizers used in bioremediation, beforehand is really good but it seems like they have mainly focused on the science but have forgotten about the logistics. If I am honest I did not think about this myself up until your comment at all. It would be interesting if Ron and Rosenberg actually have an answer to this and just forgot to mention it?