Gamma-aminobutyric acid-enriched rice produced by Paenibacillus yonginensis DCY84T seed priming enhances barrier protective and neuroprotective bioactivity in vitro co-culture

Enhancing functional metabolites in staple crops is crucial for maintaining their nutritional and health-promoting values. Gamma-aminobutyric acid (GABA) is a bioactive compound with recognized anti-inflammatory and antioxidant activities; however, its enrichment in rice through sustainable practices remains underexplored. This study investigated the effects of Paenibacillus yonginensis DCY84 T rice seed priming on postharvest rice metabolite accumulation and associated bioactivities. DCY84 T seed priming altered rice grain metabolite profiles, increasing bioactive compounds including GABA, gamma-oryzanol, and amino acids, with enhanced ABTS radical scavenging capacity ( p < 0.05). GABA content increased approximately 2.0-fold and 1.4-fold in the SN21 and SN22 cultivars, respectively, accompanied by coordinated upregulation of gene encoded to GABA biosynthesis key enzyme, glutamate decarboxylase. The metabolite-enriched rice extract mitigated lipopolysaccharide-induced intestinal inflammation in a Caco-2/RAW264.7 co-culture model by preserving tight junction protein expression and suppressing IL-1β, IL-6, and TNF-α production. In a Caco-2/SH-SY5Y gut-brain axis model, the rice extract reduced IL-8 secretion by approximately 1.5-fold and increased synaptophysin expression by 1.63-fold, indicating neuroprotective potential. Additionally, DCY84 T seed priming reshaped the soil microbiome toward taxa associated with secondary metabolite accumulation, including Sphingomonadaceae , Solibacteraceae , and Rhizobiaceae . Overall, priming rice seeds with DCY84 T displayed a microbe-plant-metabolite strategy to enhance postharvest rice nutritional quality, attributed with health benefits.