HR: 0800h
AN: H21A-0997    [Abstracts]
TI: Heterogeneity in Extracellular Polymeric Substances Production and its Effects on the Transport and Attachment of Trichloroethene Degrading Toluene Oxidizing Bacteria
AU: * Putthividhya, A
EM: Aksara.Putthividhya@tufts.edu
AF: Department of Civil and Environmental Engineering, Tufts University, 113 Anderson Hall, 200 College Ave., Medford, MA 02155 United States
AU: Abriola, L M
EM: Linda.Abriola@tufts.edu
AF: Department of Civil and Environmental Engineering, Tufts University, 113 Anderson Hall, 200 College Ave., Medford, MA 02155 United States
AU: Kukor, J J
EM: kukor@AESOP.Rutgers.edu
AF: Department of Environmental Sciences, Rutgers University, 316 Foran Hall, Cook College Campus, 59 Dudley Road, New Brunswick, NJ 08901 United States
AB: The role of extracellular polymeric substances (EPS) heterogeneity in microbial transport and retention was investigated for pure cultures of trichloroethene (TCE) degrading toluene oxidizing bacteria. A wildtype and a mutant strain of {\it Ralstonia pickettii} were employed in sand column experiments, based upon their ability to metabolize alkyl aromatic hydrocarbons and cometabolize TCE by a toluene-3-monooxygenase (T3MO) enzyme system. These wildtype and mutant strains are identical, except that the TbuX protein is knocked out in the latter, resulting in less EPS synthesis. A pulse of $^{3}$H radiolabeled cell-EPS suspension was introduced to saturated packed sand columns under steady flow conditions. Biomass and EPS were quantified in the influent, effluent, and within the porous medium. Experimental results indicate that increased EPS enhanced bacterial retention and reduced detachment. While biomass deposition (mass/g sand) declined, EPS (mg/g sand) increased with travel distance along the column. EPS mass balance calculations suggest that EPS were synthesized by surface-associated bacteria within the column. The biomass-normalized EPS along the column ranged from values that were fairly consistent with those found under free-living conditions (near the column entrance) to five-fold increases (near the column outlet), suggesting that most EPS synthesis took place in microbes deposited near the column outlet. Flow cytometric results revealed no significant change in average cell size within the two day starvation period. However, cell influent was comprised of at least two subpopulations, as assessed through differences in fluorescence intensity. Additionally, a better prediction of the observed microbial deposition pattern was achieved with a model that incorporates a power-law distribution for the particle-collector deposition rate coefficients, consistent with a variation of attachment properties within the population. This observed microbial heterogeneity could also be attributed to differential EPS coatings on cell surfaces.
DE: 1831 Groundwater quality
DE: 1832 Groundwater transport
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting