New Approaches for Bioaugmentation as a Remediation Technology

Abstract Bioaugmentation is commonly employed as a remediation technology. However, numerous studies indicate that introduced microorganisms often do not survive in the environment and thus do not increase contaminant remediation. This review details several new approaches that may increase the persistence and activity of exogenous microorganisms and/or genes following introduction into the environment. These techniques include: (1) bioaugmentation with cells encapsulated in a carrier such as alginate; (2) gene bioaugmentation where the goal is for the added inoculant to transfer remediation genes to indigenous microorganisms; (3) rhizosphere bioaugmentation where the microbial inoculant is added to the site along with a plant that serves as a niche for the inoculant's growth; and (4) phytoaugmentation where the remediation genes are engineered directly into a plant for use in remediation without a microbial inoculant. Additionally, the review discusses the generation of genetically engineered microorganisms for use in bioaugmentation along with methods for the control of the engineered microorganisms in the environment, and the potential effects of the release on indigenous organisms. Various methods for the detection of introduced microorganisms such as real-time polymerase chain reaction (PCR) and reporter genes are also addressed. Ultimately, these new approaches may broaden the application of bioaugmentation as a remediation technology. Keywords: genetically engineered microorganismimmobilized cellphytoaugmentationphytoremediationreporter genesuicide gene ACKNOWLEDGMENTS We thank Liza F. Gentry for assistance with the preparation of this manuscript. This work was supported by NIEHS Basic Superfund grant 5 P42 ESO4940-09.