半褶织纹螺体内的河豚毒素及菌群结构分析

Analysis of tetrodotoxin and microbial community structure in Nassarius semiplicatus

  • 摘要: 河豚毒素 (Tetrodotoxin, TTX) 是一种强毒性生物毒素,在自然界中分布较广。为探究半褶织纹螺 (Nassarius semiplicatus) 体内TTX的可能细菌性来源,采用液相色谱-串联质谱法,分析福建海域半褶织纹螺体内的TTX及同系物,并利用高通量测序分析含和不含TTX的织纹螺的细菌群落结构。结果显示,含TTX织纹螺 (LTN组) 中TTX的质量分数为402~644 μg·kg−1,同时检测到trideoxyTTX、dideoxyTTX、deoxyTTX等3种同系物;不含TTX织纹螺 (NTN组) 检测到微量的dideoxyTTX。高通量测序结果显示,LTN组的群落丰富度显著高于NTN组 (p<0.05);两组的主要优势菌门为变形菌门;LTN组的主要优势菌属包含弧菌属 (Vibrio)、假交替单胞菌属 (Pseudoalteromonas)、嗜冷杆菌属 (Psychrobacter) 等产TTX相关菌,NTN组包含假交替单胞菌属、希瓦氏菌属 (Shewanella)。弧菌属、嗜冷杆菌属等17个差异菌属在LTN组中的相对丰度大于NTN组 (p<0.05)。两组的菌群KEGG功能组成相似,以氨基酸代谢、碳水化合物代谢等为主。结果表明,含或不含TTX的半褶织纹螺均存在产TTX相关菌,弧菌属、嗜冷杆菌属更容易在含TTX半褶织纹螺中富集,这些菌属可能与半褶织纹螺体内TTX同系物或前体物质的生物合成有关。

     

    Abstract: Tetrodotoxin (TTX) is a potent marine toxin, found in a great variety of marine and some terrestrial species. In order to explore the potential bacterial sources of tetrodotoxin (TTX) in Nassarius semiplicatus, we collected its TTX and analogues from Fujian and analyzed them by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Besides, we compared the microbial communities of TTX-bearing and non-TTX-bearing by using high-throughput sequencing technology. The results show that the content of TTX in TTX-bearing N. semiplicatus (LTN) were 402~644 μg·kg−1. TrideoxyTTX, dideoxyTTX and deoxyTTX were detected. TTX and other analogues were not detected in non-TTX-bearing N. semiplicatus (NTN) except dideoxyTTX. The results of high-throughput sequencing show that the community richness of LTN was significantly higher than that of NTN (p<0.05). The microbial communities of LTN and NTN were dominated by Proteobacteria. TTX-producing bacteria, including Vibrio, Pseudoalteromonas and Psychrobacter, were the dominant bacteria in LTN, while Pseudoalteromonas and Shewanella in NTN. The significant difference analysis shows that the relative abundance of 17 differential genera in LTN, including Vibrio and Psychrobacter, etc., were significantly higher than that of NTN (p<0.05). The KEGG functional composition of the intestinal flora of LTN and NTN were similar. The main metabolic pathways were amino acid metabolism, carbohydrate metabolism and so on. The results show that TTX-producing bacteria can exist in both LTN and NTN; Vibrio and Psychrobacteraremore enriched in LTN. These TTX-producing bacteria may be related to the biosynthesis of TTX analogues and precursors in N. semiplicatus.

     

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