Transgenic rice expressing a novel phytase-lactoferricin fusion gene to improve phosphorus availability and antibacterial activity

The developing trends of livestock production are efficiency, safety and sustainability, which face two major challenges: low availability of phytate phosphorus and abuse of antibiotics. As a solution phytases and antimicrobial peptides are applied as feed additives. However, phytases and antimicrobial peptides are susceptible to proteases, costly by fermentation and potential toxic to production hosts. We transformed an optimized phytase-lactoferricin fusion gene PhyLf driven by an endosperm-specific promoter Gt13aP and Bar (bialaphos resistance) gene as a selection maker into rice. The Bar and PhyLf genes were integrated into the rice genome, stably inherited and expressed. Their phosphinothricin acetyl transferase (PAT) protein content of transgenic plants with glufosinate resistance varied between 50.45-93.39 μg g−1. Fusion protein expressed especially in the seeds of transgenic rice had a summit phytase activity at 32.30 U g−1, which increased by 61.71-fold compared to the control/check group (CK) and 7.54-fold compared to un-optimized transgenic plant. The highest inorganic phosphorus (Pi) content of the transgenic seeds reached 13.15 mg g−1, increased by 12.77-fold compared to that of CK. Preliminary antibacterial experiments showed that the enterokinase hydrolysate product of fusion protein could inhibit the growth of Escherichia coli DH5. These results indicated that the protein PhyLf has the potential to increase availability of feed phytate phosphorus, improve consumer's immunity and reduce the use of antibiotics.