Using CRISPR/Cas9 genome editing to facilitate antibiotic discovery in novel Streptomyces species

抗生素是我们最重要的药物之一；它们治疗一系列传染病，也用于预防免疫受损患者的感染，例如接受化疗或器官移植手术的患者。不幸的是，微生物对我们目前的抗生素产生了越来越多的抗药性，这意味着抗生素不再那么有效。迫切需要对耐药微生物具有活性的新抗生素。目前使用的抗生素中，约有三分之二是从土壤细菌(如链霉菌)自然产生的化合物中开发出来的。链霉菌被认为在环境中会产生许多抗菌化合物，但在实验室中，它们通常只会产生几种。这意味着，如果我们能在实验室中找到开启这些“沉默”途径的方法，还会从链霉菌中发现更多的抗菌分子。该项目将利用基因工程来开启从四色蚂蚁巢中分离出来的一种新菌株--福尔马链霉菌中抗生素的生产。福氏假单胞菌是一种有天赋的菌株，有可能产生许多抗菌分子。到目前为止，只有一种抗生素被确定了特征，那就是一种名为甲霉素的新抗生素家族，它是耐药微生物的有效抑制剂。通过删除负责甲氧西林产生的基因，我们已经表明，甲酸葡萄球菌开始产生以前的“沉默”化合物，包括更多对耐药微生物具有活性的新的抗菌素。在这次联谊会中，我将寻求描述这些新的抗菌剂的特征，并确定它们的临床潜力。我的另一个目标是了解福氏链球菌是如何产生这些抗菌分子的，以及为什么甲氧西林途径的缺失会导致这些以前沉默的分子的产生。通过了解这些沉默的途径是如何开启的，我们可以确定同样的方法是否可以用于全球分离的数百株其他链霉菌，从而促进许多新的抗菌分子的发现。

Antibiotics are some of our most important medicines; they treat a range of infectious diseases and are also used to prevent infections in immunocompromised patients such as those undergoing chemotherapy or organ transplant surgery. Unfortunately, microorganisms are increasingly developing resistance to our current antibiotics, meaning the antibiotics no longer work as effectively. New antibiotics that have activity against resistant microorganisms are urgently needed. Around two-thirds of currently used antibiotics were developed from compounds made naturally by soil-dwelling bacteria like Streptomyces. Streptomyces are thought to produce many antimicrobial compounds in the environment, but in the lab, they only usually make a few. This means many more antimicrobial molecules remain to be discovered from Streptomyces if we can find ways to switch on these 'silent' pathways in the lab.This project will use genetic engineering to switch on the production of antibiotics in Streptomyces formicae, a new strain isolated from the nests of Tetraponera penzigi plant-ants. S. formicae is a talented strain, with the potential to produce many antimicrobial molecules. So far, only one has been characterised; a new family of antibiotics called the formicamycins which are potent inhibitors of resistant microorganisms. By deleting the genes responsible for formicamycin production, we have shown that S. formicae starts to produce previously 'silent' compounds, including more new antimicrobials that have activity against resistant microorganisms. In this fellowship, I will seek to characterise these new antimicrobials and determine their clinical potential. I also aim to understand how the antimicrobial molecules are made by S. formicae and why deletion of the formicamycin pathway induces the production of these previously silent molecules. By understanding how these silent pathways are switched on, we can determine whether the same approach could be used in the many hundreds of other Streptomyces strains isolated across the globe, facilitating the discovery of many new antimicrobial molecules.