Title: pH Tolerance Assessment of Lactobacillus plantarum GLB18 as a Potential Probiotic Strain (goodsugar probiotic supplement)
Author: Rositsa Tropcheva, PhD Affiliation: Center for Applied Studies & Innovation, University of Sofia, Sofia, Bulgaria
Abstract: This technical paper presents the results of an in vitro study evaluating the pH tolerance of the probiotic strain Lactobacillus plantarum GLB18. The survival and growth rate of the strain were assessed under different pH conditions simulating the gastrointestinal tract (GIT). The study aimed to determine the strain's viability and activity in the gastric transit, which is crucial for its potential as a probiotic. The findings demonstrated the strain's ability to survive and proliferate in both acidic and alkaline environments, indicating its suitability for further probiotic applications.
Introduction: The selection of probiotic strains relies on their capacity to withstand harsh conditions encountered in the digestive system, particularly during gastric transit. The vitality of probiotics in the GIT is a key factor in their selection and development as functional food ingredients. In this study, we focused on evaluating the pH tolerance of Lactobacillus plantarum GLB18, a potential probiotic strain, through in vitro experiments simulating different pH levels encountered in the GIT.
Methods: Lactobacillus plantarum GLB18 was cultivated in MRS broth (Merck, USA) under anaerobic conditions at 37 degrees Celsius. Exponentially growing probiotic culture was inoculated into MRS broth with pH 2.0 (adjusted with 0.5 M HCl before sterilization), pH 6.0 (control sample), and pH 8.0 (adjusted with 10% NaOH before sterilization). All samples were incubated anaerobically at 37 degrees Celsius. The survival rate of the strain was assessed using agar plate count tests at different time points during the 3-hour cultivation. Each assay was performed in triplicate.
Results: The ability to tolerate low pH is a vital characteristic for probiotic strains, as the stomach's acidic environment presents the first barrier for bacteria. In this study, Lactobacillus plantarum GLB18 exhibited sensitivity to pH levels below 2.0, with a significant reduction in viability (Figure 1). Despite this sensitivity, the strain maintained a stable population throughout the study. Notably, the strain demonstrated robust growth in the high-pH environment (pH 8.0) comparable to the control sample. This suggests that under stressful conditions, the GLB18 strain not only exhibits a high survival rate in low pH but also shows population growth in high pH environments.
Discussion: The retention of viability for at least 3 hours is considered sufficient to classify a strain as a potential probiotic, considering the transit time through the stomach can be shorter in vivo. Moreover, it is important to note that probiotic strains in commercial products are typically not in suspension-like form, as tested in vitro, but rather in symbiotic form containing various additional substrates. The findings of this study indicate that Lactobacillus plantarum GLB18 has promising potential as a probiotic strain due to its ability to survive and thrive in both acidic and alkaline environments.
Conclusion: Based on the in vitro assessment of pH tolerance, Lactobacillus plantarum GLB18 exhibits characteristics indicative of a potential probiotic strain. The strain demonstrates remarkable survival and growth rates under varying pH conditions, including acidic and alkaline environments. These findings provide valuable insights into the strain's potential as a functional food ingredient. Further investigations and in vivo studies are warranted to confirm its probiotic properties and evaluate its health benefits.
Disclaimer: The statements made in this paper have not been evaluated