Abstract: Inorder to study antimicrobail activity of protein from Gracilaria endophytic fungi NSS1, the antimicrobial protein was prepared by ammonium sulfate precipitation, the best ammonium sulfate saturation was 65%. Antibacterial activity to bacterial indicator was detected by filter paper method, the results showed that the antibacterial crude protein could inhibit the growth of five indicator bacteria, and the best inhibitory effect was obtained when the protein concentration reached 750 μg/mL. The scavenging effect of superoxide anion free radical (O-2) from protein was detected by the pyrogallol autoxidation method. The effect of protein on tumor cells was detected by the MTT method. The antibacterial activity was stable under the condition of below 100℃ and neutral pH. The activity of protein was not sensitive to UV irradiation, glycerol, methanol and trypsin. Different concentrations of protein solution all had effect on removing superoxide anion. It had the strongest inhibitory effect on tumor cells, when the protein concentration was 360 μg/mL. Above results indicated that the antibacterial protein had strong antibacterial activity, antioxidant activity and antitumor activity.

Key words: endophytic fungi, antimicrobial protein, antimicrobial activity, antioxidant activity, antitumor activity