Optimization of nitrogen source for Bifidobacterium bifidum using response surface methodology

In order to improve the viable counts of Bifidobacterium bifidum BB01 in the liquid medium, the Central Composite Design (CCD) was used to optimize the nitrogen source in the medium of B. bifidum BB01. The results showed that the nitrogen source composition of B. bifidum BB01 was: peptone 0.9%, yeast extracts 0.3%, beef paste 0.7%. Under the optimal conditions, the viable counts of B. bifidum BB01 reached (2.49±0.06)×109CFU/mL after cultured at 18h, which was 42.97% higher than MRS (lactose), and 12.85% higher than the optimized MRS medium (carbon source and prebiotics were optimized). Therefore, the CCD used in this study is workable for promoting the growth of B. bifidum BB01.