Flow Cytometric Method Assessment of Autolysis of lactic acid bacteria

Abstract:

Abstract：[Objective] The autolysis rate of lactic acid bacteria is crucial for their applications as dairy starters and as probiotics. To establish a rapid and sensitive method to detect autolysis rate of lactic acid bacteria, A Flow Cytometric Method (FCM) can be employed. [Methods] Cell suspensions were dyed 30 min by PI-PBS (20 mmol/L) in 4℃ dark environment. A 630 nm long pass filter was used to collect the red fluorescence (FL3 488 nm), and 1×105 cells were collected each sample. Data were analyzed by CellQuest online analysis system. Test time depended on different concentrations of cell suspensions, were about 40 s to 100 s. FCM enumerations were accurate down to a concentration of 104 cells/mL. [Results] Correlation test results reported that there were no significant difference between FCM test and other normal methods for the determination of Autolysis rate of lactic acid bacteria. [Conclusion] FCM by use of fluorescent probes propidium iodide (PI) is a good analytical method that allows the rapid and sensitive measurement of viability of lactic acid bacteria. This FCM method provides tools to assess the viability of different lactic acid bacteria in fermentation starters and probiotic products.

Key words:Keywords: Flow cytometry; Lactic acid bacteria; Autolysis; Detection