Influence of Bacterial Induction on Cell Growth and Antimicrobial Peptide Activity in Insect Cell Lines NIH-SaPe-4

Abstract: Insect cell lines can be applied in the studies of antimicrobial peptides， protein (Amps) and drug development with multiple advantages. In the present study we evaluated the changes of cell density and cellular vitality in the insect cell lines NIH-SaPe-4， which originated from ovarian germ cell of adult flesh fly (Diptera: Sarcophagidae)， after inducing by Micrococcus luteus. We also assayed the activity of antimicrobial protein and the changes of activity over time. Finally， the antimicrobial protein was isolated and purified and the stability of the protein was assessed. Our result demonstrated that the inducing by bacteria caused the insect cell growth slowed and impaired the cellular vitality. Both the induced group and control group could produce antimicrobial proteins with inhibitory activity against 3 types of Gram-positive bacteria. The protein showed the strongest antibacterial activity against Micrococcus luteus. The antimicrobial activity appeared earlier in the induced cells group， and the inhibitory activity of antimicrobial protein in induced cells group was higher than in the control group. Furthermore， the antibacterial activity in the induced group returned to the same level as in the control group after the disappearance of inducing bacteria. A kind of 60 kDa antimicrobial protein was obtained， after electrophoresis and reversedphase purification， from the crude extracts of both induced and control groups. The electrophoresis band intensity from induced group was greater than which from the control group. The obtained antimicrobial protein showed pH stability and thermal stability. Our result could provide basic information for future studies which focus on purification and characterization of antimicrobial peptides and proteins from insect cell.

CSTR: 32200.14.cjcb.2012.06.0006