Novel fermentations integrate traditional practice and rational design of fermented-food microbiomes

Fermented foods and beverages have been produced around the world for millennia, providing humans with a range of gastronomic, cultural, health, and scientific benefits. Building on these traditional forms, a convergence of factors, including culinary innovation, globalization, shifts in consumer preferences, and advances in microbiome sciences, has led to the emergence of so-called 'novel fermentations'. In this review, we define novel fermentation as the confluence of traditional food practices and rational microbiome design. Using principles of microbial ecology and evolution, we develop a microbiological framework that outlines several strategies for producing and characterizing novel fermentations, including switching substrates, engrafting target species, assembling whole-community chimeras, and generating novel phenotypes. A subsequent analysis of existing traditional ferments points to gaps in 'fermentation space' where novel ferments could potentially be produced using new combinations of microbes and food substrates. We highlight some important safety and sociocultural issues presented by the repurposing and modification of microbes from traditional ferments that fermented-food producers and microbiologists need to address.