Copper Tolerance of Kelp-Associated Bacteria

Kelp forests are one of the most widespread and productive of all ecosystems. They provide habitat and nutrition to diverse communities of microorganisms, invertebrates, and mammals. Many kelp forests are dominated byMacrocystis pyrifera, a species of large brown algae that produce negatively charged polysaccharides on their cell surfaces. The polysaccharides allow Macrocystis to accumulate heavy metals such as copper, normally an essential element involved in cellular pathways. Brown algae in environments with higher levels of heavy metals, such as those near human activity, accumulate toxic levels of copper by producing larger amounts of polysaccharides. Toxic amounts of copper can then bioaccumulate up the food chain.

We hypothesize that microbial populations living in close contact with the kelp must tolerate higher levels of copper than normally found in cells. To date, 11 full genomes of algae-associated bacteria have been sequenced using 454 Life Sciences Technology. Preliminary findings suggest that the bacteria associated with kelp have genes such as the suppression of copper sensitivity (scs)locus that are absent in species from other environments. Finding the minimal inhibitory concentration (MIC) of copper in microbes from kelp, the open ocean, and terrestrial environments will elucidate the functional role of the scs genes in copper tolerance. The insertion of the scs locus into an E.colistrain may also help define a possible copper tolerance mechanism in bacteria.


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