Leuconostoc mesenteroides AA001: A High-Efficiency Nitrite Degrader Facilitating Controlled and Safe Traditional Vegetable Fermentation

In traditional vegetable fermentation, the lack of effective microbial community control often leads to excessive nitrite accumulation, a major food safety concern. To address this challenge, this study aimed to isolate and characterize a high-performance starter culture strain capable of simultaneously degrading nitrite and guiding safe, controlled fermentation. A strain of <i>L. mesenteroides</i> AA001 was isolated from traditionally fermented Yingcai. It exhibited strong nitrite-degrading activity, with degradation rates consistently exceeding 90% under various environmental conditions, and demonstrated robust environmental adaptability. When used as a starter culture in vegetable fermentation, <i>L. mesenteroides</i> AA001 significantly accelerated nitrite degradation and consistently maintained peak nitrite concentrations below the Chinese national standard limit (20 mg/kg), while also shortening the fermentation period. Moreover, inoculation with <i>L. mesenteroides</i> AA001 had no significant impact on most nutrients in fermented vegetables across 8 crucial nutritional indicators (comprising 22 specific parameters), and only β-carotene content shows differences. The sensory attributes of the inoculated samples are basically similar to those of the naturally fermented samples, except that they are significantly brighter in color. No harmful substances were detected among 16 tested safety indicators, and the profile of 46 major volatile flavor compounds showed no significant difference compared to the spontaneously fermented control. Microbial community profiling throughout fermentation revealed that early dominance by this strain rapidly established a lactic acid-driven anaerobic environment, effectively suppressing nitrite-accumulating microorganisms and steering the process toward a stable, safe, and flavor-consistent trajectory. Thus, <i>L. mesenteroides</i> AA001 is a safe starter strain that combines potent nitrite-degrading capacity with fermentation-guiding functionality, effectively ensuring safety and process controllability in traditional vegetable fermentation.