The genetic modification of bacteria from natural and managed habitats will impact on the management of agricultural and environmental settings. Potential applications include crop production and protection, degradation or sequestration of environmental pollutants, extraction of metals from ores, industrial fermentations, and productions of enzymes, diagnostics, and chemicals. Applications of this technology will ultimately include the release of beneficial agents in the environment. If safely deployed, genetically modified bacteria should be able to provide significant benefits in the management of environmental systems and in the development of new environmental control processes.
A modified freeze-thaw method in combination with reverse transcriptase PCR was developed for monitoring gene expression in activated sludge. The sensitivity of the methodology was determined by inoculating nonsterile activated sludge samples with 3-chlorobenzoate-degrading Pseudomonas putida PPO301(pRO103), which contains the catabolic tfdB gene. tfdB mRNA was detected in 10 mg of activated sludge inoculated with 10 4 CFU of the target organism. This technique was subsequently utilized to analyze the in situ expression of the catabolic dmpN gene in a sequencing batch reactor (SBR) bioaugmented with phenol-degrading P. putida ATCC 11172. Greatest dmpN expression was observed 15 min after maximum phenol concentration was reached in the reactor and 15 min after the start of aeration. Decreased phenol concentrations in the reactor corresponded to reduced levels of dmpN expression, although low levels of dmpN mRNA were observed throughout the SBR cycle. These results indicate that concentration of phenol in the reactor and the onset of aeration stimulated transcriptional activity of the dmpN gene. The information obtained from this study can be used to alter SBR operational strategies so as to lead to more effective bioaugmentation practices.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.