Gene Enhanced Remediation of Co-contaminated Soils

Mixing of biosolid waste before application on field site.

Background
Bioremediation is a low-cost approach to cleaning up sites contaminated with mixed wastes. If indigenous microbial populations do not efficiently degrade site contaminants, appropriate degradation genes may be introduced to microbes. An evaluation of gene delivery to microorganisms in situ has not yet been completed.

Goal
To evaluate in situ gene delivery as a mechanism to enhance remediation of co-contaminated soils.

Objectives
1. To evaluate new conjugative systems as a mechanism for gene delivery into the soil microbial gene pool through the introduction of whole cells.

2. To evaluate enhanced transformation as a mechanism for gene delivery into the soil microbial gene pool through the introduction of 'naked' nucleic acid.

3. To evaluate the use of biosurfactants to enhance transport of introduced genes through co-contaminated soils.

4. To evaluate the fate of 'naked' DNA introduced into soils.

Significant Findings
1. Bioaugmentation with whole bacterial cells can enhance biodegradation o f 2,4-dichlorophenoxyacetic acid or 2,3 or 4-chlorobenzoate in soils.

2. Gene bioaugmentation via horizontal transfer of degradative plasmids can enhance chlorinated hydrocarbon degradation in soil co-contaminated with cadmium.

3. Bioaugmentation with “activated soil” is a promising approach to enhancing organic degradation.

Publications

Contact
Ian Pepper
ipepper@ag.arizona.edu
520-626-3328