Conference Theme: Linking animal science and animal agriculture: Meeting the global demands of 2050Dairy Foods Symposium: Dairy Foods Consumption, Gut Microbiota, and Human HealthTraditionally, probiotics have been added to yogurt and other
fermented foods for health benefits. Currently 56 species of
Lactobacillus, including L. acidophilus and L. casei and 32
species of Bifidobacterium, exist. These probiotic cultures are
able to restore the normal balance of microbial populations
in the intestine and offer several therapeutic benefits. There
has been an increasing demand for health-promoting food
ingredients. Different milks fermented with bacteria, yeasts,
molds or enzymes offer a broad range of possibilities to cover
different health aspects with new bioactive components such
as lactoferrin, micronutrients, CLA, sphingolipids and bioactive
peptides or synthesize exo-polysaccharides. In particular,
milk-proteins and associated bioactive peptides released during
microbial or enzymatic fermentation of milk offer a broad
spectrum of new functional properties including anti-hypertensive,
anti-microbial, anti-oxidative, and immuno-modulatory
properties. Gamma-aminobutyric acid (GABA), a non
-protein amino acid, is mainly found in the brain and regulates
vertebrate physiological and psychological behaviors such as
anxiety and depression blood pressure and hormone secretion.
The synthesis of GABA in the brain decreases with age, especially
in elders. Hence, there has been increasing interest
in use of probiotics for GABA production. In this study, several
GABA-producing LAB isolates have been isolated from
naturally fermented foods such as Korean kimchi. Previous
screening methods are time-consuming and inefficient. In the
present study, we have developed a novel screening and identification
method for GABA-producing LAB from Korean
kimchi. Acid treatment was applied to screening procedure
to obtain acid-tolerant LAB isolates, and then a simple identification
of GABA-producing LAB based on release of gas
by these bacteria has been developed. The amount of GABA
produced by LAB isolates at various monosodium glutamate
(MSG) concentrations and incubation times in MRS
medium was quantified by HPLC. Genetic identification of
high GABA-producing LAB was performed by both 16S
rRNA gene and glutamate decarboxylase gene. Nine potential
GABA-producing LAB isolates were selected by observing
gas release during fermentation. The conversion ability of
MSG into GABA for all nine LAB isolates was 100% (supplementation level 10 g/L MSG, incubation time 24 h), over
80% (supplementation level 30 g/L MSG, incubation 48 h),
over 60% (supplementation level 50 g/L MSG, incubation
time 72 h) and over 50% (supplementation level 70 g/L MSG,
incubation time 72 h). These nine LAB isolates were genetically
identified as Lactobacillus brevis by 16S rRNA gene and
confirmed by glutamate decarboxylase gene.published_or_final_versio
