Rapid identification and quantitation of the viable cells of Lactobacillus casei in fermented dairy products using an aptamer-based strategy powered by a novel cell-SELEX protocol

摘要

An aptamer-based strategy was developed for qualitativeand quantitative analysis of viable Lactobacilluscasei in dairy products. Three highly specific aptamersfor L. casei were obtained using systematic evolution ofligands by exponential enrichment protocol using thewhole bacterium cell as the target (cell-SELEX) facilitatedby polyethyleneglycol and chitosan modified grapheneoxide and complementary ring-mediated rollingcircle amplification. Two aptamers, one for separatingand enriching the L. casei cells and the other for generatingfluorescence signals, were employed to develop anaptamer-based strategy, which was demonstrated forthe selective detection of L. casei in commercial dairydrinks, with a dynamic range of 10~5 to 10~9 cfu/mL. Viableand nonviable L. casei cells could be discriminatedbased on the significant difference in fluorescence intensity.This established strategy is of high selectivity andsensitivity, and can be used for rapid analysis of viableL. casei in quality control and food surveillance areas.