The Earth is overpopulated. The exponential growth of the population started in the first quarter of the twentieth century, when sufficient food was already available. This was achieved using nitrogen fertilizers, which led to an increase in agricultural productivity. Added to this was the increase in lifespan with the discovery and use of antibiotics. Population growth continues while the environment becomes polluted, climate change occurs, and microbes become resistant to antibiotics. These problems are addressed in our Balzan research topics, and chemical ecology, communication with various chemical and signaling molecules in symbiotic nitrogen fixation, may offer solutions to them.
Nitrogen is an essential element for life. Although it makes up 78% of the atmosphere, plants and animals and most microorganisms are unable to use it directly. Biological nitrogen fixation is a biochemical process in which atmospheric nitrogen is converted to ammonia by the nitrogenase enzyme complex that evolved around ~1.5–2.2 billion years ago in certain bacteria and archeae called diazotrophs. Some diazotrophs have formed symbiotic relationships with plants, the most effective of which has evolved between soil-dwelling Rhizobium bacteria and leguminous plants, one of the most widespread groups of flowering plants with many agriculturally important species such as bean, soybean, pea, chickpea, peanut, clover, and alfalfa. The interaction between Rhizobium and plant partners, from their mutual recognition to fully developed nitrogen-fixing nodules, is regulated by molecular dialogues, which include chemical signals and hundreds of peptide (small protein) effectors.
