A study by the Lawrence Berkeley National Laboratory found high concentrations of the bacteria in the deep plume of oil near the spill site during May and June.
Writing in the journal Science, lead author Terry Hazen says 100 times fewer bacteria were present outside the spill zone.
Now that most of the spill appears to be gone, the prodigious oil eaters have resorted to feeding on their dead “brethren,” which expired after consuming the oil, Hazen says.
Some scientists question the bacteria’s role in the oil disappearance.
Richard Camilli of the Woods Hole Oceanographic Institution says it's possible the oil has moved or become so diluted that it can no longer be detected.