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Interaction of bacteria and ion‐exchange particles and its potential in separation for matrix‐assisted laser desorption/ionization mass spectrometric identification of bacteria in water
Author(s) -
Guo Zhongxian,
Liu Ying,
Li Shuping,
Yang Zhaoguang
Publication year - 2009
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.4338
Subject(s) - chemistry , tap water , bacteria , mass spectrometry , chromatography , desorption , matrix assisted laser desorption/ionization , filtration (mathematics) , bacterial cell structure , adsorption , organic chemistry , biology , genetics , statistics , mathematics , environmental engineering , engineering
Abstract Identification of microbial contaminants in drinking water is a challenge to matrix‐assisted laser desorption/ionization mass spectrometry (MALDI‐MS) due to low levels of microorganisms in fresh water. To avoid the time‐consuming culture step of obtaining enough microbial cells for subsequent MALDI‐MS analysis, a combination of membrane filtration and nanoparticles‐ or microparticles‐based magnetic separation is a fast and efficient approach. In this work, the interaction of bacteria and fluidMAG‐PAA, a cation‐exchange superparamagnetic nanomaterial, was investigated by MALDI‐MS analysis and transmission electron microscopy. FluidMAG‐PAA selectively captured cells of Salmonella , Bacillus , Enterococcus and Staphylococcus aureus . This capture was attributed to the aggregation of negatively charged nanoparticles on bacterial cell regional surfaces that bear positive charges. Three types of non‐porous silica‐encapsulated anion‐exchange magnetic microparticles (SiMAG‐Q, SiMAG‐PEI, SiMAG‐DEAE) were capable of concentrating a variety of bacteria, and were compared with silica‐free, smaller fluidMAG particles. Salmonella , Escherichia coli , Enterococcus and other bacteria spiked in aqueous solutions, tap water and reservoir water were separated and concentrated by membrane filtration and magnetic separation based on these ion‐exchange magnetic materials, and then characterized by whole cell MALDI‐MS. By comparing with the mass spectra of the isolates and pure cells, bacteria in fresh water can be rapidly detected at 1 × 10 3 colony‐forming units (cfu)/mL. Copyright © 2009 John Wiley & Sons, Ltd.