Capillary Isoelectric Focusing—Useful Tool for Detection and Quantification of Lactic Acid Bacteria in Milk

The lactic acid bacteria (LAB), including lactobacilli and enterococci, represent an important part of normal microflora in humans. Simultaneously, they are frequently used as probiotics and in food industry for production of fermented milk products. The rapid and sensitive detection of these microorganisms is crucial for the quality control. In this study, the capillary isoelectric focusing (CIEF) was successfully used for the separation and characterization of probiotic LAB, L. paracasei sp . paracasei ; L. acidifarinae ; L. fermentum ; L. gasseri ; L. helveticus ; L. plantarum ; L. delbrueckii ; L. salivarius ; E . durans ; E. faecalis; and E. faecium, according to their isoelectric points (p I ). All p I s of lactobacilli and enterococci were found in the acidic part of the pH range. Subsequently, the milk samples spiked with L. rhamnosus , and E. faecium were analyzed by CIEF. The optimal adjustment of the separation conditions allowed detection and quantification of the bacteria in the sample with sufficient sensitivity. Therefore, CIEF is an efficient approach to rapid detection and separation of LAB even directly in milk products in future.