A turning point for natural product discovery--ESF-EMBO research conference: synthetic biology of antibiotic production

Vita activa in biotechnology: what we do with fungi and what fungi do with us

Filamentous fungi are fascinating microorganisms. One of the reasons why it is so worthwhile to take a closer look at them is their capacity to produce secondary metabolites. Some of these substances have the potential to be of great use for mankind, such as it was the case with penicillin and its discovery in 1928. Almost a century later, the situation in healthcare could possibly turn back to the state before the development of the first antibiotics. Due to an overuse of antibiotics we are facing a surge of multiresistant bacteria that are not inhibited by any of the currently known drugs. That was part of the background why a European research project was launched in October 2013, titled “Quantitative Biology for Fungal Secondary Metabolite Producers”, or “QuantFung”. Fifteen young scientists embarked on a new phase in their career, moving to new work environments within Europe and dedicating their work lives intensively to the quest for useful secondary metabolites. After 4 years, the QuantFung project concluded in October this year. In this commentary, we aim to convey what it means to work in this field of fungal biotechnology and how important it is to improve the efficiency of the research therein. We introduce five out of the fifteen fellows at length and let them have their say about the adventure of science, euphoric moments, prospects and doubts. We also raise questions about the current state of research in academia, something the QuantFung fellows experienced first-hand. Being a scientist often goes beyond earning money to make one’s living. This is why we also reflect on aspects of the meaning of work in our western society, where production for profit’s sake is a main driver. For that we refer to one of the most distinguished thinkers of the twentieth century, to Hannah Arendt.

How might we increase success in marine-based drug discovery?

Drug discovery from marine organisms has been underway for > 60 years and there have been notable successes in discovering, developing and introducing clinical agents derived from marine sources. Such examples include: the analgesic ziconotide and the anti cancer compound trabectedin. However, in light of the pressing need for new drugs, particularly those with anti-infective and anticancer properties, there is strong justification for increased exploration of marine organisms as sources of novel compounds. This article considers approaches that might enhance our chances of delivering new medicines from marine-based drug discovery efforts. Consideration is given to the organisms and habitats deserving of more attention and how we might make best use of these marine genetic resources. In particular, the opportunities offered by synthetic biology are highlighted because these methods allow drug discoverers to explore pathways in 'non-culturable' species and turn on natural product biosynthesis genes that are difficult to activate under laboratory conditions (so-called 'silent' gene clusters).

Fungal extrolites as a new source for therapeutic compounds and as building blocks for applications in synthetic biology

Secondary metabolic pathways of fungal origin provide an almost unlimited resource of new compounds for medical applications, which can fulfill some of the, currently unmet, needs for therapeutic alternatives for the treatment of a number of diseases. Secondary metabolites secreted to the extracellular medium (extrolites) belong to diverse chemical and structural families, but the majority of them are synthesized by the condensation of a limited number of precursor building blocks including amino acids, sugars, lipids and low molecular weight compounds also employed in anabolic processes. In fungi, genes related to secondary metabolic pathways are frequently clustered together and show a modular organization within fungal genomes. The majority of fungal gene clusters responsible for the biosynthesis of secondary metabolites contain genes encoding a high molecular weight condensing enzyme which is responsible for the assembly of the precursor units of the metabolite. They also contain other auxiliary genes which encode enzymes involved in subsequent chemical modification of the metabolite core. Synthetic biology is a branch of molecular biology whose main objective is the manipulation of cellular components and processes in order to perform logically connected metabolic functions. In synthetic biology applications, biosynthetic modules from secondary metabolic processes can be rationally engineered and combined to produce either new compounds, or to improve the activities and/or the bioavailability of the already known ones. Recently, advanced genome editing techniques based on guided DNA endonucleases have shown potential for the manipulation of eukaryotic and bacterial genomes. This review discusses the potential application of genetic engineering and genome editing tools in the rational design of fungal secondary metabolite pathways by taking advantage of the increasing availability of genomic and biochemical data.

Developing new antibacterials through natural product research

INTRODUCTION

Natural products have long been instrumental for discovering antibiotics, but many pharmaceutical companies abandoned this field and new antibiotics declined. In contrast, microbial resistance to current antibiotics has approached critical levels.

AREAS COVERED

This article gives historical perspectives by providing background about present-day economic realities and medical needs for antibiotic research, whose pipeline is mostly focused toward older known agents and newer semi-synthetic derivatives. Future research trends and projected technological developments open many innovative opportunities to discover novel antibacterials and find ways to control pathogenic bacteria without conventional antibiotics that provoke resistance.

EXPERT OPINION

The successful registration of daptomycin, retapamulin and fidaxomicin indicate the re-emergence of natural products has already begun. Semi-synthetic derivatives from other under-explored classes are progressing. More effort is being put into approaches such as total synthesis, discovery of new structural scaffolds for synthesis, alterations of biosynthetic pathways, combinatorial biosynthesis, new screening targets and new resources from which to isolate natural products. A return to successful screening of actinomycetes depends on solving the rate-limiting dereplication obstacle. Long-term solutions need to come from greater exploration of the massive numbers of uncultured microbes. An ultimate solution to the antibiotic-promoted microbial resistance cycle may lie in finding ways to control bacteria by non-lethal means.