The role of AI-2/LuxS system in biopreservation of fresh refrigerated shrimp: Enhancement in competitiveness of Lactiplantibacillus plantarum for nutrients.

ABSTRACT

Quorum sensing of lactic acid bacteria, mediated by the Autoinducer-2 (AI-2)/LuxS system, positively regulates antibacterial activity, which is an effective strategy for aquatic product preservation. This study revealed that AI-2/LuxS system regulates the nutritional competitiveness of LAB by facilitating membrane transport systems in preservation of vacuum-packaged refrigerated shrimp (VPRS), using Lactiplantibacillus plantarum SS-128 wild-type and the luxS mutant strain. In VPRS preservation, organisms that cause spoilage and total volatile basic nitrogen were significantly lower in the VPRS inoculated with L. plantarum SS-128 than those inoculated with the luxS mutant strain (L. plantarum ΔluxS/SS-128) (p < 0.05). Simulations in vitro using diluted shrimp juice showed the growth inhibitory effects of wild-type strain SS-128 on the main VPRS spoilage microorganism Shewanella baltica. This could potentially be attributed to more efficient nutrient utilization, presumably mediated by AI-2/LuxS system, as revealed by interaction analysis. In support of this, in vitro nutritional competition test showed that L. plantarum SS-128 was more competitive for nutrients when cocultured with S. baltica under conditions of limited nutrient availability. Subsequently, an integrated analysis of transcriptomic and metabolomic revealed that AI-2/LuxS enables a continuous expansion of L. plantarum SS-128 by balancing energy expenditure followed by enhancing membrane transport systems, which is the main driven forces for it to occupy a favourable niche quickly. Our results showed that the AI-2/LuxS system may regulate the nutritional competitiveness of lactic acid bacteria and may be a regulatory strategy for biological preservation of aquatic products.