Formatted Title:

Beneficial Reuse of Sediment Using Bacteria Endophytes Derived from Contaminated Sediments

Background/Objectives:

Amongst relatively low-cost and sustainable techniques, phytoremediation has been demonstrated to be suitable for remediation of a wide variety of environmental contaminants known to occur in dredged sediment, allowing reclamation and reuse of the sediment. The biodegradation pathways associated with rhizodegradation or plant-assisted bioremediation are facilitated by a “rhizosphere effect” where plant roots improve soil quality through bioturbation and increased aeration, increased porosity, deposit carbon-containing compounds into sediment and produce other compounds beneficial to microbial growth. Inoculation of trees using bacteria (endophytes) to further facilitate both the “rhizosphere effect” and in-planta contaminant degradation has also been proven to be an innovative technology which explores the transformation and degradation of environmental contaminants in varied media including sediments.

AECOM used Molecular Biological Tools Next Generation Sequencing targeting the 16S Ribosomal RNA gene in bacteria and archaea to: 1. evaluate the presence of bacteria within the dredged sediment and trees (purple willow, Salix purpurea), 2. identify what bacteria are translocating from the sediment to the tree, and 3. evaluate if the bacteria have potential to enhance phytoremediation processes to treat contaminated dredged material for beneficial reuse.

Approach/Activities:

The study involved collection and characterization of sediment samples from three confined disposal facilities surrounding the Great Lakes of Michigan, growing trees in the contaminated sediment for six months, and sequencing the microbial populations in both the sediment and trees to identify potential endophyte candidates. Maintaining healthy tree growth in the laboratory was achieved by using an irrigation schedule developed through the aid of an artificial intelligence-assisted computer program and remote moisture-sensing apparatus.

Results/Lessons Learned:

Review of the sequencing results using artificial intelligence-assisted online resources show common bacteria (known to be endophytes) in the contaminated dredged sediment, roots and tree tissue. Some of the challenges included how to evaluate the large sequencing data sets efficiently and how to handle extraneous sequencing noise generated from the occurrence of chloroplasts and mitochondria in plant tissues.

Clara Austin

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(Group 1, Poster Board #65) Beneficial Reuse of Sediment Using Bacteria Endophytes Derived from Contaminated Sediments