›› 2019, Vol. 46 ›› Issue (4): 1181-1190.doi: 10.16431/j.cnki.1671-7236.2019.04.027

• Basic Veterinary Medicine • Previous Articles     Next Articles

Effect of Antimicrobial Peptide NZ2114 on Cell Membrane,Genome and Antimicrobial Resistance of Staphylococcus aureus Isolated from Bovine Mastitis Milk

GUO Ying1,2,3,4, TENG Da3,4, WANG Xiumin3,4, MAO Ruoyu3,4, HAO Ya3,4, FAN Huan2, WANG Jianhua3,4   

  1. 1. College of Life Sciences, Tianjin Normal University, Tianjin 300387, China;
    2. Tianjin Animal Science and Veterinary Research Institute, Tianjin 300381, China;
    3. Key Laboratory of Feed Biotechnology, Ministry of Agriculture and Rural Affairs, Beijing 100081, China;
    4. Gene Engineering Laboratory, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, China
  • Revised:2019-01-31 Online:2019-04-20 Published:2019-04-22

Abstract:

The aim of this study was to elucidate antibacterial mechanism of the fungal defense Plectasin derived peptide NZ2114 against Staphylococcus aureus (S.aureus) that caused cow mastitis and its effect on inhibiting drug resistance of S.aureus in vitro.16S rRNA gene identification and disc diffusion method were used to identify the pathogenic bacteria of 55 mastitis milk samples and test their drug resistance,microdilution method was used for determining the antimicrobial activity of NZ2114 to S.aureus.The effect of NZ2114 on S.aureus cell membrane integrity and cell morphology were observed by flow cytometry and scanning electron microscope.The methods of gel retardation and circular dichroism spectrum were used to analyze the effect of NZ2114 on S.aureus genome DNA.The effect of NZ2114 on the drug resistance S.aureus was studied by incubating NZ2114 with S.aureus.The effect of NZ2114 on the drug resistance genes of S.aureus was further identified by PCR.The results showed that 10 strains of S.aureus were obtained,which were resistant to 9 antibiotics such as penicillin,and 50% of them were multidrug resistant.NZ2114 showed strong inhibitory activity against 10 strains of S.aureus,and the minimum inhibitory concentrations (MIC) were 0.5 to 1.0 μg/mL.NZ2114 could cause micromorphological change of S.aureus S7,including cell surface shrinkage,cell contents leakage,and cell lysis and propidine iodide (PI) cell membrane penetration rate was up to 5%.Additionally,NZ2114 could bind to S.aureus S7 genomic DNA and change its structure.S.aureus and 1/4×MIC NZ2114 were incubated together for 12 h,the result demonstrated that except amoxicillin and sulfanilamide,the resistance to other antibiotics of S.aureus had decreased to different extent (10% to 40%) and the elimination rate of NZ2114 to blaZ and braRS genes were 28.57% (2/7) and 22.22% (2/9),respectively.The above results proved that NZ2114 had strong inhibited activity against multidrug resistant S.aureus,and its mechanism of interfering with the membrane and intracellular DNA,which laid the cytological foundation for its low drug resistant bactericidal mechanism.At the same time,NZ2114 had elimination effect on the drug resistance and related drug resistant genes of S.aureus.Thus,NZ2114 was a promising antibiotic alternative for treatment of cow mastitis caused by S.aureus.

Key words: cow mastitis; Staphylococcus aureus; antimicrobial peptide NZ2114; antibacterial mechanism; elimination of drug resistance

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