In Vivo Toxicity Assessment of the Probiotic Bacillus amyloliquefaciens HTI-19 Isolated from Stingless Bee ( Heterotrigona itama) Honey.

This study evaluated the acute and sub-acute toxicity of B. amyloliquefaciens HTI-19 (isolated from stingless bee honey) in female Sprague Dawley rats. In an acute toxicity study, the rats received a low dosage (1 × 10 9 CFU·mL -1 ), medium dosage (3 × 10 9 CFU·mL -1 ), or high dosage (1 × 10 10 CFU·mL -1 ) of B. amyloliquefaciens HTI-19 daily orally by syringe-feeding for 14 days. For the subacute toxicity study, rats received a low dosage (1 × 10 9 CFU·mL -1 ) or a high dosage (1 × 10 10 CFU·mL -1 ) for 28 days. The probiotic feeding in acute and sub-acute toxicity studies showed no mortality or significant abnormalities in rats throughout the experimental period. In week 2 of the acute study, the body weight of the rats showed a significant increase ( p < 0.05) compared to the control. By gross and microscopic examination of organs, no evidently significant changes were observed in the morphology of organs. Serum biochemical tests and blood hematology tests also revealed no treatment-related changes. Overall, these data indicated that oral administration of B. amyloliquefaciens HTI-19 up to 1 × 10 9 CFU·mL -1 for 28 days can be considered safe.