Enhancement of gamma-aminobutyric acid levels using co-culture of B. tequilensis AKU, B. amyloliquefaciens AUK, and B. subtilis AQU as starter culture in Nigerian fermented Prosopis Africana seed (Okpeye)
摘要
This study explores strategies to enhance the production of gamma-aminobutyric acid (GABA), a bioactive compound with various health benefits, in Nigerian fermented Prosopis africana, Okpeye. GABA is primarily produced through microbial fermentation. To improve its yield, a co-culture fermentation approach was used with Bacillus tequilensis AKU, Bacillus amyloliquefaciens AUK, and Bacillus subtilis AQU as starter cultures. The goal is to optimize co-culture fermentation conditions (temperature, inoculum concentration, fermentation time and monosodium glutamate (MSG) concentration) for maximum GABA production using Response Surface Methodology (RSM). High-performance liquid chromatography (HPLC) was then used to measure the GABA levels. Result shows that the key parameters optimized were temperature at 40 °C, inoculum concentration at 2.68% w/v, incubation time set at 56.67 h, and monosodium glutamate (MSG) concentration at 1.41% w/w. The optimized fermentation conditions significantly increased GABA production by 12.02-fold, with a maximum yield of 520.63 mg/100 g of dried Okpeye, compared to the unoptimized yield of 43.30 mg/100 g. The findings highlight the effectiveness of controlled microbial co-fermentation in enhancing the functional and nutritional value of Okpeye. This study provides a scientific basis for developing GABA-enriched functional foods, promoting the valorization of traditional African fermented products. Further research should explore large-scale production and the sensory evaluation of GABA-fortified Okpeye to assess consumer acceptance and potential commercialization.