Enrichment of corn and alfalfa silage with γ-aminobutyric acid through inoculation with a screened high producing Lentilactobacillus buchneri strain

Abstract

This study aimed to enrich corn and alfalfa silages with γ-aminobutyric acid (GABA) by utilizing high GABA-producing Lentilactobacillus buchneri. Eleven strains were screened and L. Buchneri YM9 was distinguished for its superiority in GABA production, and it was subsequently applied as an inoculant on whole-crop corn and alfalfa silage. The silage treatments were control (without inoculant), AH35 (non-GABA producing strain), YM9 (high-GABA producing strain), and 40788 (commercial GABA producing strain). The results revealed that in corn silage, pH significantly declined at the initial ensiling stage (3–7 days), with the control having the lowest pH after 90 days. The control also exhibited the highest lactic acid, while L. buchneri treatments had elevated acetic acid. Similar trends were observed in alfalfa silage, with 30 % dry matter (DM) showing lower pH and higher organic acids. YM9-inoculated corn silage had higher DM loss, reduced water-soluble carbohydrates (WSC), but increased crude protein (CP) content. YM9 and 40788 treatments in whole-crop corn silage had lower glutamate (Glu) content post-ensiling, signifying effective GABA production. YM9 treatment maintained stable and higher glutamate decarboxylase (GAD) activity, resulting in the highest GABA accumulation in corn silage (1.97 g/kg DM). Likewise, YM9 and 40788 demonstrated significantly higher GABA content in 30 % (7.6 and 6.51 g/kg DM) and 40 % (5.23 and 5.32 g/kg DM) DM alfalfa silage. Beyond enhancing fermentation and nutrient preservation, YM9 strain shows promise in enriching whole-crop corn and alfalfa with ample GABA concentration, potentially exerting anticipated biological functions when consumed by animals.