standard quantitative method to measure acid tolerance of probiotic cells

• Published in: Applied microbiology and biotechnology Vol. 86; no. 1; pp. 385 - 391
• Main Authors: Chan, Eng-Seng, Lee, Peh-Phong, Ravindra, Pogaku, Krishnaiah, Kamatan, Voo, Wan-Ping
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Berlin/Heidelberg : Springer-Verlag 01.03.2010; Springer-Verlag; Springer; Springer Nature B.V
• Subjects: Acids; Biological and medical sciences; Biomedical and Life Sciences; Biotechnology; Colony Count, Microbial; Fundamental and applied biological sciences. Psychology; Gastric Acid; Humans; Hydrogen-Ion Concentration; Kinetics; Lactobacillus acidophilus - drug effects; Lactobacillus acidophilus - growth & development; Lactobacillus casei - drug effects; Lactobacillus casei - growth & development; Life Sciences; Mathematical functions; Methods; Microbial Genetics and Genomics; Microbial Viability; Microbiology; Models, Biological; Probiotics; Probiotic; pH; Initial cell concentration; Survival kinetics; Acid tolerance; Simulated gastric fluid; Stomach; Tolerance; Concentration; Method; Survival; Kinetics; Quantitative analysis
• ISSN: 0175-7598; 1432-0614
• DOI: 10.1007/s00253-009-2384-y

The aim of this work was to develop a standard quantitative method to measure the acid tolerance of probiotic cells when exposed to a simulated gastric fluid. Three model strains of different cell concentrations were exposed to a standard simulated gastric fluid of fixed volume. The fluid pH ranged from pH 1.5 to 2.5. In general, the death kinetics followed an exponential trend. The overall death constant, k d, for all strains was found to be in a power relationship with the pH value and the initial cell concentration, and it can be expressed as where k AII is defined as the acid intolerance indicator and N ₀ is the initial cell concentration (CFU/ml). This equation was validated with the experimental data with an average R ² of 0.98. The acid intolerance of cells can be quantitatively expressed by the k AII values, where higher value indicates higher intolerance. In conclusion, a standard quantitative method has been developed to measure the acid tolerance of probiotic cells. This could facilitate the selection of probiotic strains and processing technologies.