Ocean Science and Enginnering Presents Dr. Kostas Konstantinidis, GA Tech, School of Civil and Environmental Engineering and the School of Biological Sciences
Omics Investigations of Natural Microbial Communities: The Case of Oil Spills in Beachsands
The Deepwater Horizon (DWH) oil spill in 2010, one of the largest environmental accidents in history, had pronounced impacts affecting vast areas of the open ocean, deep sea, and coastal ecosystems. Biodegradation mediated by a complex network of microorganisms and their interaction with their physicochemical environment ultimately dictates the fate of these hydrocarbons.
Most of these interactions remain elusive due to the limitations of traditional, culture-based approaches, but the advent of next generation sequencing has enabled opportunities to provide new insights into these issues. To advance these issues and better understand and model microbial activities related to oil biodegradation, we integrated taxonomic, genetic and oil degradation rate data from laboratory advective flow chambers that simulated the temporal oxic-anoxic cycles observed in the natural beach sand environment.
Hydrocarbon quantification and metatranscriptomics analyses showed that oil biodegradation was not severely limited in the absence of oxygen, with microbial activities during the oxic phases further promoting the anaerobic biodegradation by re-oxidizing (and/or detoxifying) the (reduced) alternative electron acceptors and providing nitrogen, a limiting nutrient, through biological nitrogen fixation. Using genome-resolved metagenomic approaches, the key hydrocarbon degrading and nitrogen-fixing microorganism in these laboratory incubations, which made up ~30% of the total microbial community, was isolated and characterized.
This organism, provisionally named Candidatus Macondimonas diazotrophica, represents a previously overlooked family of hydrocarbon degraders that are major responders to oil spills in coastal environments worldwide. This work also generated reliable biomarkers to screen for oil degradation potential in marine ecosystems which are essential in determining if an ecosystem is more “primed” for oil biodegradation.
All underlying genomic, metagenomic and associated metadata were organized into an interactive and searchable webserver, called “Genome repository of oiled systems” or GROS (http://microbial-genomes.org/projects/GROS). GROS should facilitate future studies to further understand the interactions among microbial community members and their chemical environment that ultimately control the fate of oil spills.
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