Prior posts have discussed various aspects of the Deepwater Horizon oil spill and its impact on the biota of the Gulf.
Bioremediation has several goals. First, one uses nature to remediate contamination, saving significant sums. Second, the "food" (contaminant) should cause the bacteria to multiple so that the contamination is rapidly decreased. Researchers have found that BP oil failed to satisfy the second goal. Why and does this matter?
With the Deepwater Horizon oil spill, surface bacteria had a feast, but the feast did not result in an increase in number or weight gain by individual bacteria. Researchers found that although the bacteria more than quintupled their daily "intake" of petroleum "food", there was no increase in mass. Using enzyme measurements, researchers confirmed that the bacteria (especially those inside the slick) suffered from a shortfall of phosphorus, a nutrient essential for growth. Offering affected bacteria extra phosphorus greatly boosted their feeding rate and their proliferation.
Even without extra phosphorus, the surface bacteria broke down oil at an unprecedented rate. The researchers viewed this as a mystery.
However, other researchers have offered not unreasonable explanations. One noted that although microbial oil degradation in the surface slick proceeded faster than had been expected, this may simply reflect the bacteria's adaptation over millions of years to the large number of natural oil seeps in the Gulf of Mexico. Others argue that the fact that bacterial cells did not add mass may not be all that puzzling. They note that Gulf bacteria have evolved several mechanisms to store oil constituents that they do not use initially as fuel; instead, some bacteria transform the oil to produce dense particles within their bodies which effectively store the oil as food energy for later use.
The study can be found at http://iopscience.iop.org/1748-9326/6/3/035301.