The association and uptake of hydrophobic organic chemicals by gram-negative organisms during bioremediation processes

For this dissertation, studies were conducted to determine the transport mechanism for naphthalene by a Pseudomonas fluorescens isolate and to determine the nature of association of octadecane with the membranes of a Pseudomonas aeruginosa isolate in the presence of a mono-rhamnolipid biosurfactant. Also, a model that describes the passive diffusion of a non-charged hydrophobic organic chemical through the cellular envelope of a Gram-negative organism was developed.; In studies conducted, evidence was obtained which suggests the presence of a specific transport system for naphthalene in Pseudomonas fluorescens strain Uper-1. By monitoring the effects of azide and 2,4-dinitrophenol on naphthalene transport in strain Uper-1, which displays a Nah{dollar}sp+{dollar} phenotype, evidence was obtained supporting an energy-dependent entry of naphthalene into the cells. Also, by monitoring the effects of naphthalene analogues on naphthalene assimilation, evidence was obtained which supports the presence of a specific system for naphthalene transport in this organism. These, and additional results have indicated that cells of P. fluorescens strain Uper-1 possess an energy-dependent, protein-mediated active transport system for naphthalene assimilation.; The objective of this study is to determine the interaction of a mono-rhamnolipid biosurfactant and octadecane to the cellular envelope of Pseudomonas aeruginosa strain PG201. Evidence was obtained which shows that the association of octadecane to the membranes of strain PG201 was enhanced in the presence of the mono-rhamnolipid at levels near the critical micelle concentration. Also, the association of octadecane was more specific to the outer membrane than the cytoplasmic membrane in the presence of the mono-rhamnolipid biosurfactant.; For this study, a model was developed which describes the passive diffusion of a hydrophobic organic chemical through the cellular envelope of a Gram-negative organism. This model was used to accurately predict the biodegradation rate of octadecane in a separate mineralization study. This model shows that the partitioning of octadecane into the outer membrane and the characteristics of the periplasmic space (diffusion coefficient and thickness) are the controlling factors. Also, it was shown that the outer membrane formed a formable barrier to the partitioning of octadecane into the cellular envelope.