Comparative Evaluation of Lactobacilli and Bifidobacteria in Healthy Individuals

Abstract

Lactobacillus and Bifidobacterium spp. are known as the major group that constitutes probiotic bacteria that form part of the normal biota of humans. The ecological significance of probiotic bacteria in the human gut cannot be exaggerated as studies have revealed many of the health benefits they offer. However, much is yet to be known about its population variation between and within individuals. Five apparently healthy volunteers were recruited and advised not to consume yogurt, antibiotics, alcohol and steroid three weeks before and during the study. Three (3) fecal samples from each participant obtained at two weeks interval (total of 15 samples a week) for six weeks were examined for each subject bacteria. Samples were collected in sterile specimen jars and immediately taken to the laboratory for analysis. Rogosa and BIM-25 selective media were used for the enumeration of Lactobacillus spp. and Bifidobacterium spp. respectively using plate count method. Lactobacilli were classified at the specie level using API 50 CHL kit, while Bifidobacteria isolates were identified at the genus level by detecting the presence of Fructose-6-phosphate phosphorketolase (F6PPK) activity. Both groups of bacteria were also identified at the genus level using a genus-specific primer set. All selected isolates obtained from the respective culture media were confirmed to be Lactobacilli and Bifidobacteria. The data obtained showed that intra-individual variation of the population of Lactobacillus and Bifidobacterium spp. was significantly lower than inter-individual variation at P<0.05. This study establishes the fact that the composition level of Lactobacillus and Bifidobacterium spp. varies between healthy individuals, but with little or no variation within healthy individuals.