This study aimed to produce gamma-aminobutyric acid (GABA), a major inhibitory neurotransmitter in the nervous system, from Lactobacillus brevis IBRC 10818 using microbial biosynthesis and ultrasonic shock. Microbial biosynthesis is one of the best production methods compared to chemical synthesis. The response surface methodology (RSM) was used to optimize and model the GABA production under the influence of four shock factors: ultrasonic intensity, ultrasonic time, incubation period, and monosodium glutamate (MSG) concentration. The shock was applied during the lag phase. The optimal conditions for maximum GABA production were predicted to be 2.98 % MSG, 70.8 h incubation time, 6.30 min shock time, and 33 kHz frequency. Under these conditions, the GABA production was 266.19 mg/L, which was close to the predicted value of 212.2 mg/L. The model prediction was suitable with a high coefficient of determination (R2=0.96). Manuscript profile

Astragalus fasciculifolius Boiss. is a native medicinal plant of Iran with a long history of traditional use. This study investigated the phenolic composition, antimicrobial activity, and growth dynamics of Clostridium perfringens when treated with ethanolic extracts of A. fasciculifolius gum. Phenolic profiling revealed hesperidin as the most abundant compound (17.61%). Extracts showed antimicrobial activity, with minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of 156 and 78 mg/g against C. perfringens, respectively. Microscopy indicated membrane shrinkage and changes upon treatment. A quadratic model was developed to describe C. perfringens growth in meat over time at different extract concentrations and temperatures. Optimization predicted the lowest bacterial numbers at 7200.8 ppm extract concentration, 14.29 h storage time, and 4.0°C temperature. These results demonstrate that A. fasciculifolius gum possesses bioactive compounds with antimicrobial properties against foodborne pathogens. The extract could potentially be developed as a natural preservative for the food, cosmetics, and pharmaceutical industries. Manuscript profile