Influence Of Low-concentration Rhamnolipid On The Adsorption And Transport Of Pseudomonas Aeruginosa ATCC9027in Glass Beads

The effects of monorhamnolipid (monoRL) on the adsorption ofPseudomonas aeruginosa ATCC9027grown on glucose or hexadecane to glass beads withhydrophobic or hydrophilic surfaces was investigated using batch adsorption experiments.Results showed that adsorption isotherms of the cells on both types of glass beads fitted theFreundlich model better than the Langmuir model. The Kfof the Freundlich equation foradsorption of hexadecane-grown cell to glass beads with hydrophobic surface wasnotably higher than that for the other three combinations of cell group and surfacetype, and it decreased with the increasing rhamnolipid concentration. For both groups of cells,the zeta potential was close to each other and stable with the increase of rhamnolipidconcentration, however, the surface hydrophobicity of hexadecane-grown cells wassignificantly higher than that of the glucose-grown cells and it decreased with the increase ofrhamnolipid concentration. The results indicate the importance of hydrophobic interaction onadsorption of bacterial cells to surfaces and rhamnolipid plays a role in reducing the bacterialadsorption by affecting cell surface hydrophobicity.The effects of monoRL on the transportation of Pseudomonas aeruginosa ATCC9027grown on glucose or hexadecane to glass beads with hydrophobic or hydrophilic surfaces wasalso investigated. In this study, the cell surface hydrophobicity of hexadecane-fed cells washigher then that of glucose-fed cells, the results were consistent with that of the adsorptionexperiments. There are many factors influencing the bacterial transport in the saturatedporous media. Bacterial cells fed with different carbon resources (glucose or hexadecane)have different surface properties (zeta potential and hydrophobicity) and the glass beads dealtwith special chemical regent gained hydrophilic or hydrophobic surfaces. In addition,rhamnolipid can not only change the bacterial surface properties and the properties of theporous media, but also change the solution chemistry.When the monoRL concentration was0mg/L, the breakthrough plateau was thehighest among the other monoRL concentrations. However, monoRL reduced the cellsdeposition with the increasing monoRL concentrations. This function of monoRL can beexplained from that monoRL can change the cell surface properties. But for hexadecane-fed cells, the optimum monoRL concentration was40mg/L and at which the breakthroughplateau was the highest.