Catabolic capabilities of bacterial endophytes

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About 1500 new man-made chemicals are introduced to the world each year and 100,000 such chemicals already circulate in industrial and natural ecosystems. In Canada, a full 5,000 of these are not even properly assessed. We depend on microorganisms to eliminate these chemicals for us. Degradative bacteria are central to our municipal and industrial waste treatment systems, and we expect them to protect agricultural crops and soils by fending off pesticide residues. The more we can learn about microbes that can destroy these chemicals, the better. While much is known about particular contaminant-degrading bacteria that live in soil and which genes they use to do this clean up, there are sources of bacteria that are not fully explored. Certain bacteria, known as endophytes, are found in virtually all plants -where they benefit plant health in many ways that have come to light in recent years. One such benefit is the breakdown of toxins absorbed from polluted soils and atmospheres, such as spilled oil components, pesticides and industrial contaminants. The research described in this proposal will investigate the nature of contaminant degradation genes in bacterial endophytes, and the means by which they were acquired. One study will examine the endophytes of plants growing in natural historical oil seeps areas - where herbaceous plants grow in soils covered by oil slicks, showing a remarkable degree of adaptation to hydrocarbon toxicity. Another will investigate the bacterial partners of coffee trees that are exposed to high levels of pesticides. Several projects will delve into a specific collection of a specific group of plant-associated bacteria, isolated from different places around the world, that can break down chlorinated aromatic compounds related to pesticides and polychlorinated biphenyls. A representative of this collection carries a recently described genetic element (recombinase in trio or RIT element) that is also common in other plant associated strains in the database. We suspect this RIT element may play a role in the acquisition of new useful genes by many bacteria. The proposed research will involve a search for RITs and their associations in the existing collection and in other endophytic degradative strains. This will shed light on the importance of RITS to the development of new beneficial pathways for toxin breakdown and other useful traits. The things we find will be important to clean up technologies such as phytoremediation and to the health of our crops alike. This work will concentrate of looking for novel degradative bacteria inside plant tissues. An expanded understanding of the degradative tools available to bacterial endophytes, and the mechanisms they have to rearrange genes for beneficial effects will be valuable as Canada faces more chemicals, more spills and a changing climate.