Effect of low-concentration rhamnolipid on adsorption of Pseudomonas aeruginosa ATCC 9027 on hydrophilic and hydrophobic surfaces

Colloids and Surfaces B: Biointerfaces

Jiang

et al. 2016

Self Cite

The success of effective bioaugmentation processes for remediation of soil and groundwater contamination requires effective transport of the injected microorganisms in the subsurface environment. In this study, the effect of low concentrations of monorhamnolipid biosurfactant solutions on transport of Pseudomonas aeruginosa in an ideal porous medium (glass beads) with hydrophilic or hydrophobic surfaces was investigated by conducting miscible-displacement experiments. Transport behavior was examined for both glucose-grown and hexadecane-grown cells, with low or high surface hydrophobicity, respectively. A clean-bed colloid deposition model was used for determination of deposition rate coefficients. Results show that cells with high surface hydrophobicity exhibit greater retention than cells with low surface hydrophobicity. Rhamnolipid affects cell transport primarily by changing cell surface hydrophobicity, with an additional minor effect by increasing solution ionic strength. There is a good linear relation between k rhamnolipid-regulated cell surface hydrophobicity presented as bacterial-adhesion-to-hydrocarbon (BATH) rate of cells (R2 = 0.71). The results of this study show the importance of hydrophobic interaction for transport of bacterial cells in silica-based porous media, and the potential of using low-concentration rhamnolipid solutions for facilitating bacterial transport in bioaugmentation efforts.

Section: Methodsmentioning

confidence: 99%

“…The methods and results for component analysis are presented in ref. [35]. Hexadecane (purity ≥ 99%) was obtained from Sigma-Aldrich (St. Louis, MO).…”

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Effect of low-concentration rhamnolipid on transport of Pseudomonas aeruginosa ATCC 9027 in an ideal porous medium with hydrophilic or hydrophobic surfaces

Colloids and Surfaces B: Biointerfaces

Jiang

et al. 2016

Self Cite

Effect of low‐concentration rhamnolipid biosurfactant on Pseudomonas aeruginosa transport in natural porous media

Water Resources Research

Jiang

et al. 2017

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Enhanced transport of microbes in subsurface is a focus in bioaugmentation applications for remediation of groundwater. In this study, the effect of low‐concentration monorhamnolipid biosurfactant on transport of Pseudomonas aeruginosa ATCC 9027 in natural porous media (silica sand and a sandy soil) with or without hexadecane as the nonaqueous phase liquids (NAPLs) was studied with miscible‐displacement experiments using artificial groundwater as the background solution. Transport of two types of cells was investigated, glucose‐grown and hexadecane‐grown cells with lower and higher cell surface hydrophobicity (CSH), respectively. A clean‐bed colloid deposition model was used to calculate deposition rate coefficients (k) for quantitative assessment on the effect of the rhamnolipid on the transport. In the absence of NAPLs, significant cell retention was observed in the sand (81% and 82% for glucose‐grown and hexadecane‐grown cells, respectively). Addition of low‐concentration rhamnolipid enhanced cell transport, with 40 mg/L of rhamnolipid reducing retention to 50% and 60% for glucose‐grown and hexadecane‐grown cells, respectively. The k values for both glucose‐grown and hexadecane‐grown cells correlated linearly with rhamnolipid‐dependent CSH quantitatively measured using a bacterial‐adhesion‐to‐hydrocarbon method. Retention of cells by the soil was nearly complete (>99%). Forty milligrams per liter of rhamnolipid reduced the retention to 95%. The presence of NAPLs in the sand enhanced the retention of hexadecane‐grown cells with higher CSH. Transport of cells in the presence of NAPLs was enhanced by rhamnolipid at all concentrations tested, and the relative enhancement was greater than in the absence of NAPLs. This study shows the importance of hydrophobic interaction on bacterial transport in natural porous media and the potential of using low‐concentration rhamnolipid for facilitating cell transport in subsurface for bioaugmentation efforts.

Advances in applications of rhamnolipids biosurfactant in environmental remediation: A review

Biotech & Bioengineering

Yang³

et al. 2018

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173

The objective of this review is to provide a comprehensive overview of the advances in the applications of rhamnolipids biosurfactants in soil and ground water remediation for removal of petroleum hydrocarbon and heavy metal contaminants. The properties of rhamnolipids associated with the contaminant removal, that is, solubilization, emulsification, dispersion, foaming, wetting, complexation, and the ability to modify bacterial cell surface properties, were reviewed in the first place. Then current remediation technologies with integration of rhamnolipid were summarized, and the effects and mechanisms for rhamnolipid to facilitate contaminant removal for these technologies were discussed. Finally rhamnolipid-based methods for remediation of the sites co-contaminated by petroleum hydrocarbons and heavy metals were presented and discussed. The review is expected to enhance our understanding on environmental aspects of rhamnolipid and provide some important information to guide the extending use of this fascinating chemical in remediation applications.