In vivo safety assessment of Lactobacillus fermentum strains, evaluation of their cholesterol-lowering ability and intestinal microbial modulation.

BACKGROUND: Despite the growing importance of probiotics apparent health benefits, an impediment to the use of new
probiotic cultures is their safety. Hence there is a need to strictly examine the biosafety as well as health benefits of probiotics
in in vivo model systems.
RESULTS: In this study, two lactic acid bacterial (LAB) cultures Lactobacillus fermentum NCMR 2826 and FIX proven for their
in vitro probiotic properties were investigated for their in vivo safety in Wistar rats. An acute toxicity study (14 days) with a
high dose of biomass (1016 colony-forming units (CFU) mL−1) followed by a subchronic test for 13 weeks with oral feeding
of the probiotic cultures in three different doses (107, 108 and 1010 CFU mL−1) on a daily basis revealed the safety of the L.
fermentum cultures. The probiotic feeding had no toxic effects on survival, body weight and food consumption with any of
the dosages used throughout the treatment period. No statistically significant changes in relative organ weights and serum
biochemical and hematological indices were found between the control and the probiotic fed animals. In addition to the safety
attributes, the L. fermentum culture fed rats showed reduced serum cholesterol levels, macrovesicular steatosis and hepatocyte
ballooning compared with control animals. Further, quantification of intestinal microbiota using real-time polymerase chain
reaction (PCR) analysis from animal feces indicated a significant increase and stability of Lactobacillus and Bifidobacterium
counts but a decrease of Escherichia coli numbers.
CONCLUSION: This study of safety and beneficial features highlights the use of the two native L. fermentum isolates as potential
probiotic food supplements