A Halotolerant Lactiplantibacillus plantarum 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 Halomonas, gradually replaced Lactobacillus, 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, Lactiplantibacillus plantarum 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.