Optimization of culture conditions for and assessment of kimchi-originated lactic acid bacterial isolates toward their extracellular GABA-producing ability
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引用次数: 0
Abstract
The objectives of this study were to optimize the medium and culture conditions using a strong γ-aminobutyric acid (GABA) producer as a reference lactic acid bacterial strain, to screen and identify GABA-producing lactic acid bacterial isolates from kimchi, and to determine their extracellular GABA-producing abilities. Thin-layer chromatography was used to screen GABA-producing bacterial isolates and high-performance liquid chromatography was used to evaluate the bacterial GABA production abilities. Species-specific polymerase chain reaction analyses were used to identify GABA-producing bacterial isolates. The optimal medium and culture conditions were found to be the modified Man–Rogosa–Sharpe (MRS) broth (with an initial pH of 6.5) containing 4% sucrose, 5% glutamate, and 1% yeast extract at 37°C for 5 days. After incubation under the optimized culture conditions, 217 kimchi bacterial isolates were screened to evaluate their respective GABA-producing abilities. Screening the 217 kimchi bacterial isolates identified 24 GABA-producing lactic acid bacterial isolates (11%): Lactobacillus plantarum (17), Lactobacillus brevis (six), and Leuconostoc mesenteroides (one), indicating that only a small proportion of the strains produce GABA in the culture broth. The extracellular GABA-producing abilities of the bacterial strains identified in this study varied even within the same species, ranging from 5.8 to 101.7 mM among the 17 GABA-producing L. plantarum isolates and from 8.5 to 88.6 mM among the six GABA-producing L. brevis isolates. In summary, three species of the 24 kimchi GABA-producing bacterial isolates were identified, including one rare species (L. mesenteroides) and the two most dominant species (L. brevis and L. plantarum). Keywords: Lactobacillus brevis; Lactobacillus plantarum; Leuconostoc mesenteroides; Optimization; γ-aminobutyric acid (GABA)
期刊介绍:
The "Emirates Journal of Food and Agriculture [EJFA]" is a unique, peer-reviewed Journal of Food and Agriculture publishing basic and applied research articles in the field of agricultural and food sciences by the College of Food and Agriculture, United Arab Emirates University, United Arab Emirates.