Substrate-driven pre-adaptation during propagation shapes the metabolic behavior of Leuconostoc mesenteroides GSL1

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Leuconostoc mesenteroides GSL1 was propagated for three consecutive cycles in faba bean- and yellow pea-based media to mimic pulse-derived environments, while modified MRS broth (mMRS) was used as a control medium. Whole-genome sequencing of GSL1 revealed a broad genetic potential for carbohydrate and amino acid utilization and biosynthesis of central metabolites. Here, we investigated how propagation history shapes the phenotypic profile of GSL1 and influences its subsequent fermentative performance. Phenome profiling at the end of propagation in mMRS revealed a constitutive core metabolome (sucrose, maltose, glucose, and fructose utilization), whereas pulse-propagated cultures showed expanded carbon source utilization profile (n = 4), including N-acetyl-D-glucosamine, galactose, and mannose. These shifts were accompanied by upregulation of genes involved in carbohydrate transport and metabolism (2.9-21.5-fold increase). Propagation history influenced key fermentation traits during cross-inoculation, including lag phase (2-3 h increase), acidification (0.08-0.10 pH units decrease), and metabolites production, notably (mannitol (0.02-0.07 g/L increase) and lactic acid (0.02-0.7 g/L increase). It also affected amino acid and phenolic compound metabolism. Some patterns of amino acid utilization aligned with the genomic potential of GSL1, although gene presence alone does not confirm metabolic activity. In contrast, variations in phenolic compounds and certain amino acids likely reflected propagation-driven differences in substrate accessibility. Collectively, these findings demonstrated that propagation acts as a conditioning step that modulates the physiological state and functional responses of GSL1 across different fermentation environments, with potential implications for the optimization of pulse-based fermentation processes.

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