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

Area of Science:

• Microbiology and Fermentation Science
• Food Science and Technology
• Metabolic Engineering

Background:

• Understanding microbial adaptation is crucial for optimizing fermentation processes.
• Leuconostoc mesenteroides GSL1's genetic potential for metabolism is known.
• The impact of propagation environments on microbial phenotype requires further investigation.

Purpose of the Study:

• To investigate how propagation history in pulse-based media shapes the phenotypic profile of Leuconostoc mesenteroides GSL1.
• To assess the influence of propagation history on the subsequent fermentative performance of GSL1.
• To explore the implications for optimizing pulse-based fermentation processes.

Main Methods:

• Propagation of Leuconostoc mesenteroides GSL1 in faba bean- and yellow pea-based media versus modified MRS broth (mMRS) for three cycles.
• Whole-genome sequencing to identify genetic potential.
• Phenome profiling to analyze carbon source utilization and metabolic changes.
• Fermentation trials with cross-inoculation to assess key fermentation traits.

Main Results:

• Pulse-propagated cultures exhibited expanded carbon source utilization, including N-acetyl-D-glucosamine, galactose, and mannose, compared to constitutive utilization in mMRS.
• Upregulation of genes involved in carbohydrate transport and metabolism was observed (2.9–21.5-fold increase) in pulse-propagated cultures.
• Propagation history influenced fermentation traits: increased lag phase (2–3 h), decreased acidification (0.08–0.10 pH units), and altered metabolite production (e.g., increased mannitol and lactic acid).

Conclusions:

• Propagation history acts as a conditioning step, modulating the physiological state and functional responses of Leuconostoc mesenteroides GSL1.
• Differences in substrate accessibility during propagation influenced phenolic compound and amino acid metabolism.
• Findings suggest potential for optimizing pulse-based fermentation processes through controlled microbial propagation.