Bacillus subtilis Co-transfected with a Lysine-rich and a Methionine-rich Protein Gene and Its Effect on Cow Milk Production

The probiotic Bacillus subtilis (B. subtilis) was widely applied in animal production as feed additive. Lysine (Lys) and methionine (Met) were the two most important limiting amino acids in livestock animal feed. Raising Lys and Met contents in B. subtilis would provide better effects for animal production and save Lys and Met supplements. We still didn't know whether Lys-rich and Met-rich protein genes from plants could be transfected into B. subtilis and expressed at a high level so as to improve animal production, such as milk production as an additional diet. The Lys-rich protein gene (Cflr) and Met-rich 10 ku-δ Zein were cloned from pepper anther and maize endosperm, respectively. Then they were constructed into plasmids individually and successfully cotransfected into B. subtilis. Upon IPTG induction, mRNAs and protein expressions could be observed. Lys and Met contents in the fermentation broth were raised by 65.92% and 46.39%, respectively. After feeding 200 g and 400 g · cow⁻¹ · d⁻¹, transgenic B. subtilis fermentation broth, the milk yield, milk protein and milk fat contents all significantly increased. The Lys-rich protein gene (Cflr) and Met-rich 10 ku-δ Zein were successfully transfected into B. subtilis. Contents of Lys and Met in the transgenic B. subtilis obviously raised and the fermentation broth of the transgenic bacteria could effectively improve milk yield and quality.