Document Detail

Single-cell detection: test of microbial contamination using capillary electrophoresis.
MedLine Citation:
PMID:  17297979     Owner:  NLM     Status:  MEDLINE    
Single cells of bacteria and fungi were detected using a capillary electrophoresis-based test for microbial contamination in laboratory samples. This technique utilizes a dilute cationic surfactant buffer to sweep microorganisms out of the sample zone and a small plug of "blocking agent" to negate the cells' mobility and induce aggregation. Analysis times are generally under 10 min. Previously, a nutrient broth media was reported as an effective blocking agent; however, the natural background fluorescence from the nutrient broth limited the detection sensitivity to approximately 50 cells. In order to enhance the sensitivity of the technique down to a single cell, an alternative synthetic blocking agent was sought. Various potential blocking agents were screened including salts, polypeptides, small organic zwitterions, and surfactants. Zwitterionic surfactants are shown to be attractive alternatives to a nutrient broth blocker and mimic the nutrient broth's effects on cellular aggregation and mobility. Specifically, caprylyl sulfobetaine provided the sharpest cell peaks. By substituting caprylyl sulfobetaine in place of the nutrient broth, the fluorescence of the blocker plug was reduced by as much as 40 x. This reduction in background noise enables detection of a single microorganism in a sample and allows this technique to be potentially used as a rapid sterility test. All single cells analyzed using this technique displayed signal-to-noise ratios between 5 and 9.
Andrew W Lantz; Ye Bao; Daniel W Armstrong
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Analytical chemistry     Volume:  79     ISSN:  0003-2700     ISO Abbreviation:  Anal. Chem.     Publication Date:  2007 Feb 
Date Detail:
Created Date:  2007-02-14     Completed Date:  2007-04-12     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0370536     Medline TA:  Anal Chem     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1720-4     Citation Subset:  IM    
Iowa State University, Chemistry Department, 1605 Gilman Hall, Ames, Iowa 50011, USA.
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MeSH Terms
Bacteria / chemistry*
Electrophoresis, Capillary
Equipment Contamination
Fungi / chemistry*
Sensitivity and Specificity
Surface-Active Agents / chemistry
Time Factors
Reg. No./Substance:
0/Surface-Active Agents

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