Staphylococcus hyicus, considered as a leading pathogen of exudative epidermitis, is a serious threat to humans and animals. The emergency of bacterial resistance to antibiotics, especially in human and animal health fields, leads to an urgent need of exploration of new antimicrobial agents. In this study, NZX, a plectasin-derived peptide, was firstly expressed in Pichia pastoris X-33 and was purified by cation exchange chromatography, followed by detection of its antibacterial activity in vitro and in vivo. The results showed that the total secreted protein concentration in fermentation supernatant was up to 2820 mg/L (29 °C) after 120-h induction in a 5-L fermentor. The yield of NZX reached up to 965 mg/L with a purity of 92.6%. The recombinant expressed NZX had a strong antimicrobial activity, high stability, and low toxicity. The minimal inhibitory concentrations (MICs) of NZX and ceftriaxone (CRO) against Gram-positive bacteria were 0.46 to 0.91 μM and 6.04 to 12.09 μM, respectively. The time-killing curves showed that S. hyicus NCTC10350 was killed completely by 2× and 4 × MIC of NZX within 24 h. NZX also exhibited the intracellular activity against S. hyicus in Hacat cells. After treatment with NZX (10 mg/kg) and CRO (60 mg/kg), the survival rates of mice were 100% and 83.3%, respectively. NZX inhibited the bacterial translocation, downregulated pro-inflammatory cytokines (TNF-α/IL-1β/IL-6), upregulated the anti-inflammatory cytokine (IL-10), and ameliorated multiple-organ injuries (the liver, spleen, lung, and kidney). This study provides evidence that the expressed NZX has the potential to become a powerful candidate as novel antimicrobial agents against S. hyicus infections.

中文翻译：

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一种新的高产抗菌肽NZX及其在体外/体内对葡萄球菌的抗菌活性。

葡萄球菌被认为是渗出性表皮炎的主要病原体，对人类和动物构成严重威胁。细菌对抗生素的抗性的紧急情况，特别是在人和动物健康领域中，导致迫切需要探索新的抗微生物剂。在这项研究中，NZX是一种从凝集素衍生的肽，首先在巴斯德毕赤酵母X-33中表达，并通过阳离子交换色谱法纯化，然后在体内和体外检测其抗菌活性。结果表明，在5-L发酵罐中诱导120小时后，发酵上清液中的总分泌蛋白浓度高达2820 mg / L（29°C）。NZX的产量高达965 mg / L，纯度为92.6％。重组表达的NZX具有很强的抗菌活性，高稳定性和低毒性。NZX和头孢曲松钠（CRO）对革兰氏阳性细菌的最低抑制浓度（MIC）分别为0.46至0.91μM和6.04至12.09μM。时间杀灭曲线表明，在24小时内，NZX的2x和4 x MIC完全杀死了hy.usicus NCTC10350。NZX还显示出在Hacat细胞中针对葡萄球菌的细胞内活性。用NZX（10 mg / kg）和CRO（60 mg / kg）处理后，小鼠的存活率分别为100％和83.3％。NZX抑制细菌移位，下调促炎细胞因子（TNF-α/IL-1β/ IL-6），上调抗炎细胞因子（IL-10）并减轻多器官损伤（肝，脾，肺）和肾脏）。这项研究提供了证据，表明表达的NZX有可能成为抗S的新型抗菌剂的有力候选者。