虾源达卡气单胞菌全基因组分析和致病性研究

Whole-genome analysis and pathogenicity of Aeromonas dhakensis isolated from shrimps

目的为了解虾源达卡气单胞菌的毒力、耐药基因分布和全基因组信息,并初步评估达卡气单胞菌的致病性。方法对虾源分离株进行分子鉴定和多位点序列分型;利用β-溶血和胞外蛋白酶实验、秀丽隐杆线虫液体毒性实验、细胞毒实验、小鼠实验及毒力基因检测研究其致病性;通过药敏实验及耐药基因检测分析其耐药特征;利用eggnog、Prophage Hunter工具对全基因组序列进行分析。结果菌株18FX22鉴定为达卡气单胞菌。该菌的致病性主要表现:有β-溶血能力和胞外蛋白酶活性;对秀丽隐杆线虫、小鼠成纤维细胞和小鼠均有致病性。经检测,该菌携带7种毒力基因和12种耐药基因,发现其对阿莫西林/克拉维酸、头孢唑林和多粘菌素3种药物有耐药性。全基因组测序结果发现:18FX22的全基因组大小为4811079 bp,GC含量为61.33%。COG注释发现18FX22共有3850个基因,具有20类功能。前噬菌体预测结果发现18FX22的基因组中含有2个前噬菌体序列。全球达卡气单胞菌的聚类结果显示该菌与GCA016729585的进化关系更近。结论本研究从商品虾分离出达卡气单胞菌,发现该菌株的毒性较强,指示应加强海鲜食品安全的管控,并为达卡气单胞菌的防治提供参考。

ObjectiveTo investigate the virulence,drug resistance genes,and whole genome information of Aeromonas dhakensis from shrimp and preliminarily evaluate the pathogenicity of Aeromonas dhakensis.Methods Molecular identification and MLST typing of shrimp isolates were performed.The pathogenicity of this strain was examined byβ-hemolysis,extracellular protease,liquid toxicity test,cytotoxicity,and mouse tests,and virulence gene detection.The characteristics of drug resistance were analyzed by a drug sensitivity test and drug resistance gene detection.Eggnog and Prophage Hunter tools were used to analyze the whole genome sequence.ResultsThe 18FX22 strain was identified as Aeromonas dhakensis.The pathogenicity of this strain was characterized byβ-hemolysis and extracellular protease activity.It was pathogenic to Caenorhabditis elegans,mouse fibroblasts,and mice.The strain was resistant to amoxicillin/clavulanic acid,cefazolin,and polymyxin,which carried 10 virulence genes and 12 drug resistance genes.Whole genome sequencing showed that the whole genome size of 18FX22 was 4811079 bp and GC content was 61.33%.COG annotation indicated that 18FX22 had 3850 genes with 20 classes of functions.Prophage prediction revealed that the 18FX22 genome contained two prophage sequences.Cluster analysis of Aeromonas dhakensis worldwide showed that this strain was more closely related to GCA016729585.ConclusionsAeromonas dhakensis was isolated from commercial shrimp and found to be highly toxic,indicating that the control of seafood food safety should be strengthened.This study provides a reference to prevent and control Aeromonas dhakensis infection.