Green transition incites to food innovation, notably to favor the acceptability of plant proteins in a context of diet including replacement of animal proteins. Lactic acid bacteria (LAB) are largely used for food fermentations. The use of different LAB strains as starter with different properties can bring complementary functionalities participating to the overall quality of fermented food (acidification, texture, aroma) [1]. Fermentation can also benefit from interactions between LAB, resulting in a more efficient fermentation process. In soy yogurt production, few is known about positive LAB interactions beneficial to fermentation process. We investigated the metabolism of Lactobacillus delbrueckii CIRM-BIA 865 (Ld865) and Lactiplantibacillus plantarum CIRM-BIA 777 (Lp777) two strains efficient to ferment soy juice (SJ) [2]. We aimed to reveal how Lp777 and Ld865 interact to improve SJ fermentation. When these strains were co-cultivated in SJ, the fermentation time to obtain a yogurt-like texture was reduced by 30% compared to monocultures. Furthermore, Ld865 cells were four times shorter and ten times more numerous in cocultures than in monocultures [3]. Thanks to transcriptomic and metabolic analyses carried out during the course of fermentation, we compared adaptations of both bacterial metabolisms in coculture versus in monoculture. Transcriptomics data showed that Lp777 induced the expression of genes involved in the regulation of redox potential at a higher level in coculture than in monoculture. The redox potential in the co-cultured SJ was intermediate of monocultured SJ. A better regulation of the redox potential in coculture seems to involve metabolism of sulfur compounds (methionine, cystine) and the degradation of hydrogen peroxide by Lp777. Moreover, Ld865 and Lp777 metabolized diverse carbon and nitrogen sources. Ld865 has an homofermentative metabolism, only consumed sucrose and produced lactic acid [3]. Lp777 consumed sucrose, galactose and amino acids released by proteolytic activities of Ld865. Its metabolism is homofermentative at the beginning of acidification and further heterofermentative, producing lactic and acetic acids. Finally, LAB interactions, i.e. cooperation for redox management, cross-feeding for nitrogen and competition for carbon, in soy yogurt can be compared to previously described milk ones. In conclusion, associating LAB strains with distinct and complementary metabolic profiles can be useful to improve SJ fermentation. Identifying the molecular nature of bacterial interactions opens new avenues for the selection of cooperating strains in plant-based fermentation, thus facilitating green transition of food production