The Expression Of Antimicrobial Peptide MET In Pichia And It’s Associated With Antibiotics In Vitro Bacteriostasis

Overuse of antibiotics will lead to drug resistance, so the most important thing is to find a new kind of antibiotics. Antimicrobial peptides can destroy the cell membrane of bacteria then it will be died. In the other hand it is difficult to develop drug resistance and has wide antimicrobial properties so it can be used as a new antibiotic.The majority of antimicrobial peptides have been known are natural products and they can’t be used as antibiotics. In this paper antimicrobial peptides MET was expressed in the Pichia pastoris, then it was purified. At the end of this paper we studied the antibacterial activity of MET combined use of antibiotic.According the amino acid sequence of MET in the Genbank the nucleotide sequence was designed. In this paper we constructed a recombination vector and translated in GS-115 successfully. Protein was induced by methanol and detected by SDS-PAGE. The results of SDS-PAGE indicated that MET was expressed successfully. Using coomassie brilliant blue method measured the contents of MET in the medium were 132μg/m L。Determination the MIC of antibacterial peptide MET and antibiotics(Ampicillin, Cephalexin, ciprofloxacin, Doxycycline hyclate, Florfenicol, B, Polymyxin Roxithromycin, Streptomycin sulfate). Synergy was observed when the peptide MET was combined with different antibiotics by FIC.(1) The interaction of peptide MET and doxycycline hydrochloride in E.coli, which showed the synergistic effect;(2) The antibacterial peptide MET and polymyxin B together in S.aureus showed a synergistic effect, and interaction of roxithromycin in S.aureus showed enhancement effect;(3) Antibacterial peptide MET with roxithromycin combined action on pig salmonella showed synergy, together with the polymyxin B in pig salmonella showed enhanced role;(4) Antibacterial peptide MET with ampicillin, erythromycin, streptomycin sulfate used in combination to B.parahemolyticus resistance performance for the collaborative relationship, and cefmetazole, ciprofloxacin, doxycycline hydrochloride, Florfenicol, polymyxin B combination of B.parahemolyticus show to strengthen;(5) Antibacterial peptide MET with the joint action of ampicillin, polymyxin B in S.dysenteriae showed enhanced role;(6) Antibacterial peptide MET with florfenicol, polymyxin B in combination with the A.hydrophila show synergy, but the joint action of ampicillin, cefmetazole, streptomycin sulfate in A.hydrophila showed enhanced bacterium;(7) Antibacterial peptide MET and florfenicol, polymyxin B combination in P.aeruginosa showed enhancement effect;(8) The joint action of antibacterial peptide MET and polymyxin B in the C.perfringens showed cooperative relationship, but the joint action of doxycycline hydrochloride, florfenicol, roxithromycin in the C.perfringens showed enhancement effect. The results show that, the antibacterial peptide with different antibiotics has different effects on different strains.This study provides a reference for MET combined use of antibiotics and lays the foundation for further study of antimicrobial peptides used as a new kind of antibiotic.