title: Sorption and distribution of copper in unsaturated Pseudomonas putida CZ1 biofilms as determined by X-ray fluorescence microscopy.
abstract: The spatial and temporal distribution of metals in unsaturated Pseudomonas putida CZ1 biofilms was determined using synchrotron-based X-ray fluorescence microscopy (XRF). It was found that Fe, Mn, and Ca were mainly distributed near the air-biofilm interface of a biofilm grown on 40 mM citrate, while there were two Fe-, Mn-, and Ca-rich layers within a biofilm grown on 10 mM citrate. The sorption of copper by biofilm grown in medium containing 10 mM citrate was rapid, with copper being found throughout the biofilm after only 1 h of exposure. Copper initially colocalized with Fe and Mn element layers in the biofilm and then precipitated in a 40-μm-thick layer near the air-biofilm interface when exposed for 12 h. Cu K-edge X-ray absorption near edge structure (XANES) analysis revealed that Cu was primarily bound with citrate within the biofilm, and the precipitate formed in the biofilm exposed to copper for 12 h was most similar to copper phosphate. LIVE/DEAD staining revealed that cells at the biofilm-membrane interface were mostly alive even when the copper concentration reached 80.5 mg copper g(-1) biomass. This suggests that the biofilm matrix provided significant protection for cells in this area. These results significantly improve our understanding of metal acquisition, transportation, and immobilization in unsaturated biofilm systems.
authors.affiliation: Academy of Water Science and Environmental Engineering, Zhejiang University, Hangzhou 310029, People's Republic of China.
authors.forename: Guangcun
authors.initials: G
authors.lastname: Chen
authors.forename: Xincai
authors.initials: X
authors.lastname: Chen
authors.forename: Yuanqiang
authors.initials: Y
authors.lastname: Yang
authors.forename: Anthony G
authors.initials: AG
authors.lastname: Hay
authors.forename: Xiaohan
authors.initials: X
authors.lastname: Yu
authors.forename: Yingxu
authors.initials: Y
authors.lastname: Chen
mesh_terms: D018441:Biofilms; D002118:Calcium / Q000032:analysis / Q000378:metabolism; D019343:Citric Acid; D003300:Copper / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D007501:Iron / Q000032:analysis / Q000378:metabolism; D008345:Manganese / Q000032:analysis / Q000378:metabolism; D008856:Microscopy, Fluorescence; D016958:Pseudomonas putida / Q000378:metabolism*; D013052:Spectrometry, X-Ray Emission
chemical_list: D019343:Citric Acid; D008345:Manganese; D003300:Copper; D007501:Iron; D002118:Calcium