Identification, Classification and Screening for γ-Amino-butyric Acid Production in Lactic Acid Bacteria from Cambodian Fermented Foods

Abstract

Screening for various types of lactic acid bacteria (LAB) that form the biological agent γ-amino-butyric acid (GABA) is important to produce different kinds of GABA-containing fermented foods. So far, no GABA-producing LAB have been reported from Cambodian fermented foods. Most small-scale fermentations and even some industrial processes in this country still rely on indigenous LAB. The application of GABA-producing autochthonous starters would allow the production of Cambodian fermented foods with an additional nutritional value that meet the population’s dietary habits and that are also more attractive for the international food market. Matrix-assisted laser desorption/ionizing time-of-flight mass spectrometry (MALDI-TOF MS) and partial 16S rDNA sequencing were used to identify 68 LAB isolates from Cambodian fermented foods. These isolates were classified and grouped with (GTG)5 rep-PCR, resulting in 50 strains. Subsequently, all strains were investigated for their ability to produce GABA by thin layer chromatography. GABA-positive strains were further analyzed by the GABase assay. Of the six GABA-positive LAB strains—one Lactobacillus futsaii, two Lactobacillus namurensis, and three Lactobacillus plantarum strains—two Lactobacillus plantarum strains produced high amounts of GABA (20.34 mM, 16.47 mM). These strains should be further investigated for their potential application as GABA-producing starter cultures in the food applications.

Biogenic Amine Contents and Microbial Characteristics of Cambodian Fermented Foods

“…At the Department of Food Science and Technology, Vienna, the samples were checked shortly after arrival and kept in their original containers at 4 • C until analysis. All samples were analyzed within the usual shelf-life of the products [21].…”

“…Thus, even higher BA amounts could be expected for these products in this country. Paork chav (fermented fish) and other fermented fish products are stored at room temperature up to a year [21]. In the case of fermented vegetables, the salt content seems to be particularly relevant for the storage time.…”

A Brief Review on Glutamate Decarboxylase From Lactic Acid Bacteria

“…Diversity of GABA-producing LAB, isolation sources and GABA production. GABA concentrations as found in food products fermented with this strain or from biocatalytic, while-cell transformations of glutamate are given L. plantarum paork kampeus 20 mM [1] Weissella hellenica ika-kurozukuri 7.69 g/L [41] NR; Not Reported.…”

“…Traditionally, fermented food samples containing GABA are used to screen for and isolate GABA-producing LAB, and it is not surprising that food samples with high GABA content may result in the isolation of promising strains showing good GABA-forming properties. Typical fermented foods used for isolating GABA-producing LAB are kimchi, where in one study 68 out of 230 LAB isolates showed the ability to convert glutamate to GABA [44] or other fermented vegetable, cheese [16] or fermented milk products, as well as various fermented meat or fish products including sausages, Thai fermented fish plaa-som [45], or traditional fermented Cambodian food, mainly based on fish, where 6 out of 68 LAB isolates showed a significant GABAproducing ability [1]. These screening / isolation strategies often resulted in the identification of strains capable of efficiently converting glutamate or in the discovery of novel, not-yet-identified producers of GABA, which show promise as starter cultures for various fermented foods enriched in GABA.…”

“…Even though many genera of bacteria produce lactic acid as their primary or secondary metabolic end-product, the term 'lactic acid bacteria' is conventionally reserved for genera in the order Lactobacillales, which includes Lactobacillus, Lactococcus, Leuconostoc, Pediococcus and Streptococcus, and in addition Carnobacterium, Enterococcus, Oenococcus, Tetragenococcus, Vagococcus, and Weisella. LAB are important for a wide range of fermented foods, and are widely used as starter cultures in traditional and industrial food fermentations [1].…”