Microbial networks are the basis of every ecosystem and biological process: from global nutrient cycles on Earth to the health of our intestinal gut. These networks include multiple species of microorganisms, including bacteria and fungi, that coexist, communicate and compete among each other. Understanding microbial interactions strongly benefits agriculture, food production, biotechnology and medicine: for example, opportunistic bacteria and fungi usually infect simultaneously patients of pulmonary cystic fibrosis, and their interplay influences the course of the disease and the most suitable treatment. Multi-microbial infections are also responsible for huge losses in agriculture, such as in “brown blotch disease” in cultivated mushrooms and in “rice seedling blight”, that actually involves an intriguing symbiosis between fungi and bacteria [1]. On the other hand, bacteria and fungi associate in many everyday environments, also playing many beneficial roles, for instance in bio-remediation of oil spills and wine production [2].

Microbial communicate with each other by small chemical compounds, called natural products (also "secondary metabolites"), whose important biological activities are exploited to treat diseases and fight agricultural pests. For example, antibiotics such penicillins and pesticides such Bt-toxins are natural products from Penicillium fungi and Bacillus thuringiensis bacteria respectively, and about the half of the drugs to treat human diseases approved between 1997 and 2003 years in USA were natural products, or were inspired by them [3]. In fact, research on secondary metabolites have a huge impact for society, as highlighted by the European Commission inthe Horizon 2020 program: on one hand, the challenge of antibiotics resistance is at the top of the list of priorities for the Scientific Panel for Health; on the other hand, the safe and sustainable treatment of agricultural pests is crucial to ensure Food Security and Sustainable use of the European natural resources.

The search for new natural products is a never-ending quest, but considering that many microorganisms have a huge hidden biosynthetic potential, we can optimistically expect that the drugs of the future are still undiscovered.