发现新型抗生素的非培养方法
Title：
Culture-independent discovery of the malacidins as calcium-dependent antibiotics with activity against multidrug-resistant Gram-positive pathogens
Abstract：
Despite the wide availability of antibiotics, infectious diseases remain a leading cause of death worldwide. In the absence of new therapies, mortality rates due to untreatable infections are predicted to rise more than tenfold by 2050. Natural products (NPs) made by cultured bacteria have been a major source of clinically useful antibiotics. In spite of decades of productivity, the use of bacteria in the search for new antibiotics was largely abandoned due to high rediscovery rates. As only a fraction of bacterial diversity is regularly cultivated in the laboratory and just a fraction of the chemistries encoded by cultured bacteria are detected in fermentation experiments, most bacterial NPs remain hidden in the global microbiome. In an effort to access these hidden NPs, we have developed a culture-independent NP discovery platform that involves sequencing, bioinformatic analysis and heterologous expression of biosynthetic gene clusters captured on DNA extracted from environmental samples. Here, we describe the application of this platform to the discovery of the malacidins, a distinctive class of antibiotics that are commonly encoded in soil microbiomes but have never been reported in culture-based NP discovery efforts. The malacidins are active against multidrug-resistant pathogens, sterilize methicillin-resistant Staphylococcus aureus skin infections in an animal wound model and did not select for resistance under our laboratory conditions.
All Authors：
Bradley M Hover,Seong-Hwan Kim,Micah Katz,Zachary Charlop-Powers,Jeremy G Owen,Melinda A Ternei,Jeffrey Maniko,Andreia B Estrela,Henrik Molina,Steven Park,David S Perlin,Sean F Brady
First Authors：
Bradley M Hover
Correspondence：
Sean F Brady
摘要：
以往获得抗生素的主要来源是培养细菌的天然产物，由于细菌可培养率低，使得大量潜在抗生素难于被发现； 发现根据抗生素生物合成基因的保守序列设计引物，构建扩增子文库，再依据文库序列预测和查找新型的基因元件，结合进一步的宏基因组测序和异源表达，是一种不依赖培养的策略；使用新策略在土壤中发现了一个新的抗生素，此抗生素分布广泛、Ca离子依赖型、抗MRSA菌，被命名为malacidins；新抗生素在小鼠感染模型中效果佳，不产生选择耐药性。