Abstract:

This study investigated the preparation of lyophilized powder of Bifidobacterium bifidum and assayed its tolerance to simulated human gastrointestinal environment and stability during storage at 37 ℃. Three methods used to prepare lyophilized powder of Bifidobacterium bifidum were described as follows: Method 1: B. bifidum strain was amplified by culturing in reconstituted milk based medium and mannitol was then added as cryoprotectant to prepare lyophilized powder; Method 2: B. bifidum strain was amplified by culturing in PTYG medium and a bacterial mud was then obtained after hypothermal centrifugation. Finally, mannitol as cryoprotectant was added to the bacterial mud to prepare lyophilized powder; Method 3: A bacterial mud obtained as described in Method 2 was added with mannitol as cryoprotectant, gelatin as embedding medium, skim milk powder as excipient to prepare lyophilized powder. The results indicated that a higher viable count was observed in the lyophilized powder prepared by Method 2, which was up to 1.31 × 1010 CFU/g and although exposed to simulated gastrointestinal environment, the lyophilized powder exhibited a viable count of up to 4.19 × 108 CFU/g, which suggests that the lyophilized powder has excellent tolerance to gastric acid and bile acid. The classic accelerated experiment proved that the lyophilized power obtained Method 2 had good stability during storage at 37 ℃ and the viable count still kept at a magnitude of 107 after storage for up to one year.

Key words: Bifidobacterium bifidum, bacterial mud, cryoprotectant, lyophilized powder, viable count of B. bifidum