Use of Pseudomonas Starvation Promoters in In-Situ BioremediationEPA Grant Number: R823390
Title: Use of Pseudomonas Starvation Promoters in In-Situ Bioremediation
Investigators: Matin, Abdul , Hahm, D. H. , Keyhan, Mimi , Rivkina, Marian
Current Investigators: Matin, Abdul , Hahm, D. H. , Keyhan, Mimi , Pandza, S. , Park, C. H. , Rivkina, Marian
Institution: Stanford University
EPA Project Officer: Manty, Dale
Project Period: August 15, 1995 through August 14, 1998
Project Amount: $401,960
RFA: Exploratory Research - Environmental Biology (1995) RFA Text | Recipients Lists
Research Category: Biology/Life Sciences , Health , Ecosystems
Description:The objective of this research is to construct recombinant P. putida strains in which the capacity to degrade trichloroethylene (TCE) is de-coupled from the need for rampant growth. Pollution of the natural environment by dangerous compounds such as TCE and others is widespread. Natural bacterial populations possess the metabolic potential to degrade many of these compounds, yet little spontaneous (intrinsic) bioremediation appears to occur. The most common reason for this is a dearth of nutrients in the natural environments, which permits only slow growth and little expression of the biodegradative potential. A current experimental technology thus relies on the feeding of nutrients to acquifers, soils, etc., to stimulate bacterial growth and the biodegradative activity. However, large amounts of nutrients have to be fed. It has been estimated, for example, that to dehalogenate 16.3 Kg of TCE (a typical amount per m3 of a contaminated soil), would require 970 Kg of lactate and produce 140 Kg of bacterial biomass.
The enzyme toluene monooxygenase (TMO) of Pseudomonas mendocina KR1 can degrade TCE. All bacteria appear to possess special regulatory elements (the starvation promoters) that are preferentially expressed in slow-growth state. They control synthesis of proteins essential for survival in this state and differ in their expression from most other gene controlling elements, including those regulating expression of the biodegradative genes, which are expressed primarily during rapid growth. The approach is therefore to bring the TMO gene-cluster (which encodes TMO) under the control of a Pseudomonas starvation promoter, so that the TCE biodegradative activity would be preferentially expressed in slowly growing Pseudomonas sp. Since this genus is widely distributed in contaminated environments, its recombinant constructs can be used for in-situ bioremediation. The starvation promoter-TMO gene complex will be integrated into the Pseudomonas chromosome and the organisms tested for TCE degradation in simulated lab. systems and eventually in-situ.