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Title: Capillary zone electrophoresis for enumeration of Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus in yogurt
Authors: Orathai Lim
Worapot Suntornsuk
Leena Suntornsuk
King Mongkuts University of Technology Thonburi
Mahidol University
Keywords: Biochemistry, Genetics and Molecular Biology;Chemistry
Issue Date: 15-Mar-2009
Citation: Journal of Chromatography B: Analytical Technologies in the Biomedical and Life Sciences. Vol.877, No.8-9 (2009), 710-718
Abstract: Enumeration of Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus is a priority due to their importance in yogurt production. Capillary electrophoresis (CE) of both bacteria could be achieved in 7.2 min with a resolution of 3.2 in the background electrolyte (BGE) containing 4.5 mM Tris(hydroxymethyl) amminomethane (TRIS)-4.5 mM boric acid-0.1 mM ethylenediamine tetraacetate (EDTA) (TBE) buffer (pH 8.4) and 0.05% (v/v) polyethylene oxide (PEO), using a capillary of 47.5 cm (effective length) × 100 μm i.d., injection of 50 mbar × 3 s followed by -5 kV × 120 s, a voltage and temperature of 20 kV and 25 °C, respectively. Appropriate amounts of PEO in the BGE, sample preparation (i.e. vortex) and introduction were key factors for their separation. A short hydrodynamic injection followed by applying reversed polarity voltage could compress the bacteria into narrow zones, which were detected as separated single peaks. Method linearity (r2> 0.99), precision (%RSDs < 9.3%), recovery (%R = 91.7-106.7%) and limit of quantitation (1.0 × 106colony forming unit per mL (CFU/mL)) were satisfactory. Results from the CE analysis of both bacteria in yogurt were not statistically different from those of the plate count method (P > 0.05). The CE method can be used as an alternative for quantitation of L. delbrueckii subsp. bulgaricus and S. thermophilus in yogurt since it was reliable, simple, cost and labor effective and rapid, allowing the analysis of 3 samples/h (comparing to 2d/sample by plate count method). © 2009.
ISSN: 15700232
Appears in Collections:Scopus 2006-2010

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