Isolation and characterization of plant-based lactic acid bacteria from spontaneously fermented foods using a new modified medium

The development of starter cultures tailored to different plant-based materials plays a crucial role in achieving better fermented plant-based dairy alternatives (PBDA). Therefore, the isolation and study of new plant-based lactic acid bacteria (LAB) strains is essential. In this study, we developed a new medium for LAB isolation. Results showed this medium supported faster growth for all the 23 tested model strains, compared to the growth on M17 or MRS. Using the newly developed medium, 136 LAB strains belonging to 23 species and 11 genera were isolated from 73 spontaneously fermented food samples after a rigorous de-replication process. In addition, uptake of plant-based carbohydrates were studied. Only four strains were able to ferment all tested sugars efficiently. Furthermore, the production of butter aroma compounds in fermented commercial PBDA, including coconut, oat, rice, hemp, pea, hazelnut, and soy milk was also determined. These results demonstrated significant variations in the performance of fermenting PBDA by using different strains, with E. casseliflavus and L. sakei identified as efficient butter aroma producers in most of the tested conditions. Notably, certain strains also exhibited different behaviors when fermenting different substrates. The findings may provide valuable insights into developing new non-dairy fermented cultures with desired attributes.