Exploring Diversity of Lactic Acid Bacteria for the Development of Plant-Based Dairy Alternatives

Plant-based alternatives have gained enormous interest in the past few years, but especially the dairy alternatives suffer from lack in both taste and texture. The quality is improving, but it is still often produced by a combination of many different ingredients and additives to get somewhat close to what they try to mimic. This is in contrast to the general consumer trend, calling for “clean label” products, and may be detrimental to acceptance of these products. However, the green transition in food systems is an important step to reach the emission- and climate goals set forth by the UN in the Sustainable Development Goals. Implementation of lactic acid fermentation could be a potential solution and has already been implemented in certain products. This is however seldom very efficient, as the bacteria deployed are optimized to grow in milk, and not plant material.

This thesis investigates the use of plant-derived lactic acid bacteria that have not been through the evolutionary domestication in milk, but rather optimized to thrive in plant-associated substrates. The main aim of the project was to screen candidates for fermented, plant-based dairy alternatives, and investigate their abilities in terms of flavor development. This was done through strain isolation, application to plant-based substrates such as soybean and brewers’ spent grain, and their genomic and phenotypical traits to convert plant-associated substrates to valuable dairy-related flavor compounds. Further, we investigated the natural sources of the antimicrobial peptides bacteriocins through a metagenomics study, demonstrating a powerful tool for narrowing the search for strains of food-related relevance. Most of the work in this thesis was performed on the genus of Leuconostoc, which is an important flavor producer in cheese production, as well as an ubiquitous genus of lactic acid bacteria in most plant material.

The thesis concludes that specific Leuconostoc strains from our local strain collection can positively contribute to future development of plant-based dairy alternatives, and that metagen-omics might be a promising tool for narrowing the niches of interest when searching for bacteriocin producing lactic acid bacteria for food application.