PDF(Pubmed)
Abstract：
Aeromonas salmonicida is an important pathogen that causes furunculosis in trout and salmon with high morbidity and mortality, resulting in significant economic losses in aquaculture. Overuse of antibiotics has led to the continuous emergence of drug-resistant strains. Hence, there is an urgent need to find an alternative environmentally friendly antimicrobial agent. In this study, we isolated a virulent phage of A. salmonicida, named ASG01, which belongs to the Myoviridae family and maintains lytic activity at a pH value range from 4 to 12 and in the temperature range from 30 °C to 60 °C. The whole genomic sequence of ASG01 showed 82% similarity to Aeromonas phage pAh6-C. The cell wall hydrolase (Cwh)-encoding gene from the genome of ASG01 was predicted and heterologously expressed. Notably, in the absence of additional phage genes, endogenous expression of Cwh could lyse E. coli cells and greatly inhibit the growth of tested fish pathogenic bacteria. The lytic activity of Cwh was eliminated when the predicted active site was mutated. These results indicate that Cwh of ASG01 possessed excellent lytic activity and a wide antibacterial spectrum, suggesting its potential as an effective enzybiotic.
摘要：
沙门氏菌气单胞菌是一种重要的病原体，可在鳟鱼和鲑鱼中引起fur结核病，具有很高的发病率和死亡率。给水产养殖造成重大经济损失。抗生素的过度使用导致耐药菌株的不断出现。因此，迫切需要找到一种替代的环境友好的抗微生物剂。在这项研究中,我们分离出了一个沙门氏菌的毒液,命名为ASG01，属于Myoviridae家族，在4至12的pH值范围和30°C至60°C的温度范围内保持裂解活性。ASG01的全基因组序列显示与气单胞菌噬菌体pAh6-C的82%相似性。预测并异源表达了来自ASG01基因组的细胞壁水解酶（Cwh）编码基因。值得注意的是,在没有其他噬菌体基因的情况下，内源性表达的Cwh可以裂解大肠杆菌细胞，并极大地抑制受试鱼病原菌的生长。当预测的活性位点突变时,Cwh的裂解活性被消除。这些结果表明，ASG01的Cwh具有优异的裂解活性和广泛的抗菌谱，表明其作为一种有效的酶的潜力。
