Industrial microbiology and biochemical engineering research commonly evaluate freely suspended planktonic cells; however, in natural environments most bacteria congregate at interfaces to form polymicrobial aggregates, such as mats, flocs, sludge, or biofilms. Through quorum sensing and increased gene transfer, organisms in a biofilm matrix are able to live longer and conserve induced metabolic pathways. The increase in survival and microbial adaptations, presents benefits for biofilm-mediated bioremediation. Understanding the complex nature of the biofilm matrix may enhance current biotechnology applications and enable specially designed strategies for biofilm removal. In this study, the molecular and chemical distribution occurring within a biofilm matrix is evaluated by identifying functional group characteristics and physicochemical properties of the atrazine degrading bacterium, Pseudomonas sp. strain ADP. ADP was grown in a drip biofilm reactor in a nutrient limited medium with atrazine as its sole nitrogen source and also in a nutrient rich medium without atrazine to compare cells response to atrazine particles in the matrix. ADP mineralizes atrazine through a series of hydrolytic reactions to carbon dioxide and ammonia. A non-invasive technique, Raman spectroscopy, was used to differentiate free cells from cells in biofilm, characterize extracellular substances, and detect differences in phenotypes. Raman spectra of effluent showed relative decrease in atrazine content leaving the bioreactor over time; data was supported by gas chromatography coupled with mass spectrometry analysis. Scanning electron microscopy (SEM) enabled detailed visualization of ADP biofilm with confirmation of associated extracellular matrix structure. The extracellular matrix appeared to serve as an immobilizing agent, trapping atrazine particles in the web-like structure. Atrazine in the media provided an additional substrata for cellular adhesion. Raman spectroscopy complemented with SEM, proved to be useful in distinguishing physiological and biochemical properties among cells of the same species. Success of this research will contribute to the development of more efficient systems for biotransformation.

Identification of functional group characteristics and physicochemical properties of Pseudomonas sp. strain ADP biofilm

251st National Meeting (2016)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.