The importance of insects for angiosperm pollination is widely recognized. In fact, approximately 90% of all plant species benefit from animal-mediated pollination. However, only recently, a third part player in this story has been properly acknowledged. Microorganisms inhabiting floral nectar, among which yeasts have a prominent role, can ferment glucose, fructose, sucrose, and/or other carbon sources in this habitat. As a result of their metabolism, nectar yeasts produce diverse volatile organic compounds (VOCs) and other valuable metabolites. Notably, some VOCs of yeast origin can influence insects’ foraging behavior, e.g., by attracting them to flowers (although repelling effects have also been reported). Moreover, when insects feed on nectar, they also ingest yeast cells, which provide them with nutrients and protect them from pathogenic microorganisms. In return, insects serve yeasts as transportation and a safer habitat during winter when floral nectar is absent. From the plant’s point of view, the result is flowers being pollinated. From humanity’s perspective, this ecological relationship may also be highly profitable. Therefore, prospecting nectar-inhabiting yeasts for VOC production is of major biotechnological interest. Substances such as acetaldehyde, ethyl acetate, ethyl butyrate, and isobutanol have been reported in yeast volatomes, and they account for a global market of approximately USD 15 billion. In this scenario, the present review addresses the ecological, environmental, and biotechnological outlooks of this three-party mutualism, aiming to encourage researchers worldwide to dig into this field.

Yeasts are the most used microorganisms for biotechnological purposes. Although they have been mainly recognized for their application in the beverage and bioethanol industries, these microorganisms can be efficiently employed in pharmaceutical and food production companies. In these industrial sectors, yeasts are highly desirable for their capacity to produce bioactive compounds from simple substrates, including wastes. In this review, we present the state of the art of bioactive compound production in microbial cell factories and analyze the avenues to increase the productivity of these molecules, which benefit human and environmental health. The article addresses their vast biological activities, from preventing to treating human diseases and from pre to postharvest control on agroindustrial streams. Furthermore, different yeast species, genetically engineered or not, are herein presented not only as biofactories of the referred to compounds but also as their targets. This comprehensive analysis of the literature points out the significant roles of biodiversity, bioprospection, and genome editing tools on the microbial production of bioactive compounds and reveals the value of these approaches from the one health perspective.

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Among the seventeen sustainable development goals (SDGs) of the United Nations 2030 Agenda, at least ten rely on better usage and valuation of wastes since this attitude leads to economic and sustainable development, water-food-energy security, and environmental protection. Considering the worldwide amount of daily produced agroindustrial residues and the employment of enzymes and/or microbial cells in transformation processes, biorefineries represent a growing economic sector with high potential to meet Agenda 2030's SGDs. Indeed, by employing lignocellulosic materials as feedstocks and microorganisms as catalysts, second-generation (2G) biorefineries stand out as a productive environment able to provide several high-added value compounds. This is the case for volatile organic compounds (VOCs), including ethanol, produced by yeasts from lignocellulosic hydrolysates. This chapter reviews the ecological yeast-insect-angiosperm relationship that is the reason behind most of the VOCs generated in natural environments. From then on, the chapter advances to biotechnological and sustainable traits of using lignocellulosic wastes in yeast fermentation processes aiming to produce these high-added value compounds.