Separating Microbes in the Manner of Molecules. 1. Capillary Electrokinetic Approaches

Abstract

Selective, high-efficiency separations of intact bacteria may, in some cases, allow them to be identified and quantified in much the same way that molecules are done today. Two different capillary electrokinetic approaches were utilized. The first approach used a dissolved polymer-based CE separation that may be affected by size and shape considerations. Another approach uses capillary isoelectric focusing to separate bacteria by their surface charge or isoelectric point. Good peak shapes and extremely high efficiencies are observed (up to approximately 1,600,000 theoretical plates/m). Careful sample preparation and separation runs are essential in order to obtain reproducible separations. Expansion of these types of rapid, efficient microbial separations could have profound effects on many branches of science and technology.

Peer Reviewed: Selectivity in CE

“…However, the partial filling technique-a finite plug of selectivity agent that terminates before the analyte reaches the detector (50)-and MS can lessen this problem. CE selectivity will grow as it takes on the challenge of new applications, such as the separation of bacteria and other microbes (51).…”

Detection of microbial food contaminants and their products by capillary electromigration techniques

“…On the other hand, by the time the two latter papers mentioned [32,33] came to light, Armstrong and co-workers had published a novel manner of separating microorganisms in exceptional sharp peaks [34]. In various reports, authors demonstrated that the use of small amounts of polyethylenoxide (PEO, i.e.…”

“…Although critically controlled buffer and sample preparation steps were required to keep the cells intact and the separation reproducible [34], variations in the migration time of microorganisms were sometimes observed among samples. This effect was associated to the different ionic strength of the analyzed samples [35].…”

Rapid Separation of Microorganisms by Quartz Microchip Capillary Electrophoresis

“…1 In recent years, advances have been made in the application of capillary electrophoresis (CE) to the separation of biological cells including microorganisms. [2][3][4][5][6][7][8] The cell surfaces consist of a variety of charged polymers and, in most cases, have a net negative charge at physiological pH. We had previously developed a rapid and highly sensitive method for detecting bacteria using CE coupled to a laser-induced fluorescence (LIF) detection system.…”

“…To solve these problems, we added polymers to the running buffer because they had been reported to improve the peak shape during the separation of microorganisms by CE. For example, Armstrong and co-workers [6][7][8] have achieved the rapid and highly efficient separation of mixtures containing several species of bacteria and fungi by adding polyethylene oxide (PEO) to the CE running buffer. PEO was effective in this case because it promotes microorganism aggregation during electrophoretic migration.…”