title: Adsorption of monorhamnolipid and dirhamnolipid on two Pseudomonas aeruginosa strains and the effect on cell surface hydrophobicity.
abstract: Previously, adsorption feature of a dirhamnolipid biosurfactant on diverse microbial cells was studied and the effect of the adsorption on cell surface hydrophobicity was compared. In this paper, the adsorption behavior of a monorhamnolipid and a dirhamnolipid on cells of two Pseudomonas aeruginosa strains was investigated in order to further reveal the influence of biosurfactant structure and cell property on the adsorption and the relation between the adsorption and cell surface hydrophobicity. Experimental results showed that the adsorption capacity of all the cells to monorhamnolipid was much stronger than to dirhamnolipid, and the rhamnolipid-sourced P. aeruginosa cells, no matter grown on glucose or hexadecane, released extra dirhamnolipid when aqueous concentration of dirhamnolipid was too high. Length of surfactant alkyl chain as well as the type of carbon source used to cultivate the cell adsorbents had only minor influence on the adsorption. The adsorption was assumed to be driven by polar interaction between the rhamnolipid molecules and the cell surface chemical groups. The directional orientation of the rhamnolipid molecules with hydrophobic moiety extending to the environment may account for the rapid increase of cell surface hydrophobicity at low aqueous concentrations of the surfactant, while the stable or decreased cell hydrophobicity was probably the consequence of multiple surfactant layer formation or hemimicelle accumulation.
authors.affiliation: College of Environmental Science and Engineering, Hunan University, Changsha, China.
authors.forename: Hua
authors.initials: H
authors.lastname: Zhong
authors.forename: Guang Ming
authors.initials: GM
authors.lastname: Zeng
authors.forename: Jian Xiao
authors.initials: JX
authors.lastname: Liu
authors.forename: Xiang Min
authors.initials: XM
authors.lastname: Xu
authors.forename: Xing Zhong
authors.initials: XZ
authors.lastname: Yuan
authors.forename: Hai Yan
authors.initials: HY
authors.lastname: Fu
authors.forename: Guo He
authors.initials: GH
authors.lastname: Huang
authors.forename: Zhi Feng
authors.initials: ZF
authors.lastname: Liu
authors.forename: Ying
authors.initials: Y
authors.lastname: Ding
mesh_terms: D001422:Bacterial Adhesion; D006017:Glycolipids / Q000737:chemistry / Q000378:metabolism*; D057927:Hydrophobic and Hydrophilic Interactions; D011550:Pseudomonas aeruginosa / Q000502:physiology*; D013499:Surface Properties; D013501:Surface-Active Agents / Q000378:metabolism*
chemical_list: D006017:Glycolipids; D013501:Surface-Active Agents; C418382:rhamnolipid; C051310:rhamnolipid hemolysin, Pseudomonas aeruginosa