Beans germination as a potential tool for GABA-enriched tofu production.

Gamma-aminobutyric acid (GABA) is an inhibitory neurotransmitter that can be found in many plants, especially beans. Beans are normally used for producing vegetarian foods, such as bean milks, bean sprouts, and tofu. Thus, the aims of this study were to determine the GABA content in various germinated beans (yellow beans, black beans, green beans, and red beans) as well in tofu products made from different types of germinated beans. The results showed that soaking and germination significantly contributed to an increase in GABA production. The GABA content increased to a maximum value of 0.89, 3.09, 3.93 and 4.78 mg/g in yellow beans, red beans, green beans, and black beans, respectively. Moreover, due to the bean characteristics, green beans, red beans, and black beans were collected at 6 h after germination while yellow beans were collected at 0 h after germination. As a result, only yellow bean sprouts could be used for tofu production since they are composed of a high amount of proteins and a low amount of carbohydrates. The GABA content in tofu was 0.55 mg/g, which was lower than that in soybean milk (0.65 mg/g), likely due to the filtration and pressing processes of tofu production.

Understanding the hindrance factor of bacterial proliferation and γ-aminobutyric acid-producing capability of nondairy strains of Lactiplantibacillus plantarum in milk fermentation.

γ-aminobutyric-acid (GABA) is a mental health-supporting substance that helps release anxiety and depression and improves memory. Lactiplantibacillus plantarum SKKL1, a GABA-producing bacterium, has been introduced to formulate a gut-brain axis product. However, growth and sugar consumption of L. plantarum SKKL1 in milk were ineffective. This obstacle was investigated by varying different types of milk, sugars, fermentation temperatures, and times. The results revealed that none of these parameters improved growth and bacterial metabolism in milk, except addition of soluble protein as found in yeast extract and malt extract. Although a protease deficiency of L. plantarum SKKL1 was discovered, it was not a primary barrier to cell propagation. Insight of this study showed clearly that soluble protein was an essential metabolic activator for growth, nutrient consumption, and protease synthesis, then stimulated lactic acid and GABA productions. While, milk casein and casein hydrolysate, a complex protein structure with low solubility, were not utilized by L. plantarum SKKL1. The novelty of this study is the first in-depth investigation to confirm a significant effect of soluble protein on enrich-GABA milk fermentation by L. plantarum SKKL1 as the sole starter without protease and monosodium glutamate addition.

Antioxidant and Anticancer Potential of Bioactive Compounds from Rhinacanthus nasutus Cell Suspension Culture.

The potential benefits of natural plant extracts have received attention in recent years, encouraging the development of natural products that effectively treat various diseases. This is the first report on establishing callus and cell suspension cultures of Rhinacanthus nasutus (L.) Kurz. A yellow friable callus was successfully induced from in vitro leaf explants on Murashige and Skoog medium supplemented with 1 mg/L 2,4-dichlorophenoxyacetic acid and 1 mg/L 1-naphthalene acetic acid. A selected friable callus line was used to establish the cell suspension culture with the same medium. The antioxidant assays showed that the leaf- and ethanolic-suspension-cultured cell (SCC) extracts exhibited high antioxidant potential. In addition, the in vitro cytotoxicity revealed by the MTT assay demonstrated potent antiproliferative effects against the oral cancer cell lines ORL-48 and ORL-136 in a dose-dependent manner. Several groups of compounds, including terpenoids, phenolics, flavonoids, quinones, and stilbenes, were identified by UHPLC-QToF-MS, with the same compounds detected in leaf and SCC extracts, including austroinulin, lucidenic acid, esculetin, embelin, and quercetin 3-(2″-p-hydroxybenzoyl-4″-p-coumarylrhamnoside). The present study suggests the value of further investigations for phytochemical production using R. nasutus cell suspension culture.

Thermotolerant bacteriocin-producing lactic acid bacteria isolated from thai local fermented foods and their bacteriocin productivity.

Twenty-one samples of Thai local fermented foods were screened for thermotolerant bacteriocin-producing lactic acid bacteria. From 529 isolates of lactic acid bacteria, 121 isolates were able to inhibit the growth of certain bacterial strains. Of these 121 isolates, only 11 produced antibacterial agents that were capable of inhibiting the growth of multiple bacterial strains in a liquid medium. One strain (KKU 170) of these 11 isolates produced an antibacterial agent that could strongly inhibit the growth of selected strains of gram-positive bacteria including Listeria sp. The antibacterial agent produced by the strain KKU 170 was identified as a bacteriocin since it was inactivated by proteinase K treatment. The strain KKU 170 was identified as Pediococcus acidilactici by both biochemical tests and molecular biological techniques. Optimal production of bacteriocin by the strain KKU 170 was found in culture medium containing 0.2% glucose, at an initial culture pH of 6.5, and temperature of 45 ºC. The maximum bacteriocin activity (1600 AU ml(-1)) was reached at the late exponential phase of growth and displayed primary metabolite production. The partially purified bacteriocin of the strain KKU 170 was tolerant to heat treatment at 121 ºC for 30 min.

Grass degrading beta-1,3-1,4-D-glucanases from Bacillus subtilis GN156: purification and characterization of glucanase J1 and pJ2 possessing extremely acidic pI.

Purification of beta-1,3-1,4-glucanase from the cell-free culture fluid of Bacillus subtilis GN156 by affinity chromatography of epoxy-activated sepharose 6B and ultrafiltration technique resulted in homogeneous J1 and partially purified pJ2 enzymes. The molecular weight and pI of J1 were 25 kDa and 3.5, respectively, while those for J2 were 90 kDa and 3.6, respectively. Both beta-1,3-1,4-glucanase J1 and pJ2 had optimum pH values of 6-6.5 and an optimum temperature of 60 degrees C. Both enzymes were not inhibited by Li(2+) but were inhibited significantly by Ca(2+), Cu(2+), Mn(2+) and Zn(2+). However, J1 was slightly inhibited by Fe(2+), while pJ2 was inhibited by Mg(2+) as well. They were highly specific to only barley beta-glucan. K (m) and V (max) values of J1 were 1.53 mg/ml and 8,511 microU/ml.min, respectively, while those for pJ2 were 4.36 mg/ml and 7,397 microU/ml.min, respectively. Degradation of barley beta-1, 3-1,4-glucan resulted in four different oligosaccharides with 1,3 linkages triose, tetrose, pentose and a high molecular weight (HMW) with 1,3 linkage estimated from their mobilities. The quantitative degradation by the crude enzyme after of incubation yielded in descending order: triose, pentose and tetrose, while that of J1 in descending order yielded: pentose, triose and tetrose. The pJ2 showed low activity yielding a degradation pattern in descending order: pentose, triose, tetraose and a HMW polysaccharide.