摘要
      南极微生物是进化适应的重要因素，也是生物活性化合物的自然资源，具有生物合成天然产物的特殊代谢途径。然而，对南极地区鱼类的共生微生物群知之甚少。在本研究中，进行了培养方法和全基因组测序。进行了天然产物分析，以确定生物合成潜力。我们报道了一种共生细菌Serratia myotis L7-1的分离和鉴定，该细菌具有高度适应性，并存在于南极鱼类伯氏银耳中。基因组分析显示，南极菌株S.myotis L7-1具有碳水化合物活性酶（CAZymes）、生物合成基因簇（BGCs）、应激反应基因、抗生素抗性基因（ARGs）和完整的IV型分泌系统，可以促进在极端南极环境中的竞争和定殖。微生物组基因簇的鉴定表明了生物活性化合物的生物合成潜力。基于生物活性引导的分级纯化，serranticin被鉴定为生物活性化合物，显示出显著的抗菌和抗肿瘤活性。serranticin基因簇被鉴定并定位在铬上。此外，多药耐药性和强大的细菌拮抗作用有助于在生态位中发挥竞争优势。我们的研究结果强调了南极鱼类中共生细菌的存在，这种共生细菌主要以生物活性天然产物为代表，并具有在南极海洋鱼类中生存的适应性。
Abstract
Antarctic microbes are important agents for evolutionary adaptation and natural resource of bioactive compounds, harboring the particular metabolic pathways to biosynthesize natural products. However, not much is known on symbiotic microbiomes of fish in the Antarctic zone. In the present study, the culture method and whole-genome sequencing were performed. Natural product analyses were carried out to determine the biosynthetic potential. We report the isolation and identification of a symbiotic bacterium Serratia myotis L7-1, that is highly adaptive and resides within Antarctic fish, Trematomus bernacchii . As revealed by genomic analyses, Antarctic strain S. myotis L7-1 possesses carbohydrate-active enzymes (CAZymes), biosynthetic gene clusters (BGCs), stress response genes, antibiotic resistant genes (ARGs), and a complete type IV secretion system which could facilitate competition and colonization in the extreme Antarctic environment. The identification of microbiome gene clusters indicates the biosynthetic potential of bioactive compounds. Based on bioactivity-guided fractionation, serranticin was purified and identified as the bioactive compound, showing significant antibacterial and antitumor activity. The serranticin gene cluster was identified and located on the chrome. Furthermore, the multidrug resistance and strong bacterial antagonism contribute competitive advantages in ecological niches. Our results highlight the existence of a symbiotic bacterium in Antarctic fish largely represented by bioactive natural products and the adaptability to survive in the fish living in Antarctic oceans.

https://www.osti.gov/biblio/1909301