Through the formation of polymer secretion and chemotaxis, organisms in a biofilm are able to live longer, resist protozoan grazing, and withstand harsh environmental exposure in comparison to planktonic cells. The robust nature of cells existing in a biofilm matrix may cause chronic infection in the human body, but have many positive implications in bioremediation. In bioremediation, a biofilm system has potential in treatment of recalcitrant compounds due to its ability to immobilize compounds, access pollutants for degradation as a result of chemotaxis, and experience enhanced gene transfer amongst organisms in the matrix. For the purposes of this study, we examine the cellular activity and biotransformation that occur within layers of <i>Pseudomonas</i> sp. strain ADP biofilm as it catabolizes atrazine in comparison to free cells. ADP is 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 under nutrient limited conditions with atrazine particles in the matrix. ADP mineralizes atrazine through a series of hydrolytic reactions to carbon dioxide and ammonia. The accumulation and disappearance of intermediates depend on the expression of atrazine pathway genes. In-situ reverse transcriptase (ISRT) and other in-situ fluorescence methods are applied to probe atz gene expression within layers of the biofilm. A non-invasive technique, Raman spectroscopy, is used to differentiate free cells from cells in biofilms, examine extracellular substances, and detect intermediates to determine degradation rate. Combining ISRT, Raman spectroscopy, scanning electron microscopy, and extracellular fractionation it is possible to determine the degradative capacity within a biofilm. Success of this research will lead to improved remediation applications involving biofilms and development of non-invasive techniques to examine both internal and spatial distribution of compounds present in biofilms.

Analyzing the degradation capacity within <i>Pseudomonas </i>sp. strain ADP biofilm

249th National Meeting (2015)

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Analyzing the degradation capacity within Pseudomonas sp. strain ADP biofilm