A Halotolerant <i>Lactiplantibacillus plantarum</i> Strain from Pickled White Radish: Multi-Omics Guided Screening and Performance Validation under High-Salt Conditions

In traditional white radish pickling, high salt inhibits spoilage microbes but also suppresses LAB activity, posing a modernization challenge. This study utilized a three-stage gradient salting fermentation model, combining high-throughput sequencing, untargeted metabolomics, and enhanced fermentation techniques. During the main fermentation phase, bacterial diversity decreased markedly as halotolerant genera, such as <i>Halomonas</i>, gradually replaced <i>Lactobacillus</i>, leading to diminished lactic acid. Meanwhile, more compatible solutes were accumulated at this stage (e.g., ectoine and proline) through glycine/serine/threonine and arginine/proline metabolism. A salt-tolerant strain, <i>Lactiplantibacillus plantarum</i> LP-12, was isolated from the pickling matrix and demonstrated exceptional functionality under 8% salinity conditions, producing more lactic acid and GABA. Enhanced fermentation using LP-12 increased its dominance and enhanced the radish puree's total acidity, GABA content, and fruity-floral volatile compounds, while lowering nitrite content. This study provides a matrix-specific solution centered on halotolerant LAB for improving the quality and modernizing the production of high-salt pickled vegetables.