Microbes degrade plume from Gulf of Mexico oil spill

In the aftermath of the explosion of BP’s Deepwater Horizon drilling rig in the Gulf of Mexico, a dispersed oil plume was formed at a depth between 3,600 and 4,000ft that extended approximately 10 miles out from the wellhead.

’Our findings show that the oil profoundly altered the microbial community by significantly stimulating deep-sea psychrophilic [cold temperature] gamma-proteobacteria that are closely related to known petroleum-degrading microbes,’ said Terry Hazen, a microbial ecologist with Berkeley Lab’s Earth Sciences Division.

’This enrichment of psychrophilic petroleum degraders with their rapid oil biodegradation rates appears to be one of the major mechanisms behind the rapid decline of the deepwater dispersed oil plume that has been observed.’

Hazen and his colleagues began their study on 25 May 2010. At that time, the deep reaches of the Gulf of Mexico were a relatively unexplored microbial habitat.

’We deployed two ships to determine the physical, chemical and microbiological properties of the deepwater oil plume,’ Hazen said. ’The oil escaping from the damaged wellhead represented an enormous carbon input to the water column ecosystem and while we suspected that hydrocarbon components in the oil could potentially serve as a carbon substrate for deep-sea microbes, scientific data was needed to prove our suspicions.’

The analysis of the samples was undertaken using Berkeley’s Lab Phylochip - a credit-card-sized DNA-based microarray that can be used to detect the presence of up to 50,000 different species of bacteria and archaea in a single sample from any environmental source, without the need of culturing.

Use of the Phylochip enabled Hazen and his colleagues to determine that the dominant microbe in the oil plume was a new species of microbe, closely related to members of Oceanospirillales family, particularly Oleispirea antarctica and Oceaniserpentilla haliotis.