Probiotic Attributes, GABA-Producing Capacity and Cytotoxic Effects of Microbes Isolated from Thai Fermented Foods

Abstract

Mental illnesses and cancer deaths have been alarmingly increased in Thailand over the past decade. There is a search for an alternative remedy from natural sources. This work revealed the probiotic attributes of eighteen microbes from Thai fermented food sources, their neurotransmitter-producing capacities and cytotoxic effects. The probiotic attributes were comprehensively assessed by gelatin hydrolysis, antibiotic susceptibility, auto-aggregation, virulence gene detection, hemolytic activity, hydrophobicity determination, bile and acid tolerance. Neurotransmitters were produced from precursors by microbes over 3 days and analyzed by high-throughput LC-MS/MS. Cytotoxic effects of the selected microbial extracts on MCF-7, HepG2, and HeLa were determined using MTT assay. The results showed that only seven strains; Enterococcus casseliflavus 3.10A1, Enterobacter xiangfangensis 4A-2A3.1, Saccharomyces cerevisiae TC6, Pedicoccus pentosaceus WS11, Lactococcus lactis subspp. lactis TBRC 375, Lactobacillus brevis TBRC 3003 and Bifidobacterium adolescentis TBRC 7154 exhibited promising probiotic potential in every probiotic assessment. Only E. xiangfangensis 4A-2A3.1 and Bacillus spp. PS15 were capable of producing gamma-aminobutyric acid (GABA) from monosodium glutamate (20 mg/mL). GABA production of 4.60 μg/mL over 2 days was found in E. xiangfangensis 4A-2A3.1; however, Bacillus spp. PS15 produced the highest GABA at 5.57 μg/mL on day 1. Moreover, B. adolescentis TBRC 7154 extract showed the lowest IC50 values against MCF-7 (750.02 μg/mL), HepG2 (681.08 μg/mL), and HeLa (425.50 μg/mL) followed by E. xiangfangensis 4A-2A3.1, E. casseliflavus 3.10A1 and P. pentosaceus WS11. These microbes can be used as probiotic supplement with neurodegeneration preventive or chemopreventive potential. © 2021 Friends Science Publishers

Evaluation of GABA Production by Alginate-Microencapsulated Fresh and Freeze-Dried Bacteria Enriched with Monosodium Glutamate during Storage in Chocolate Milk

“…The calibration curve was constructed within the linearity range of 10-500 ng/mL. Samples were prepared according to the method described by Luang-In and co-workers [30], with slight modifications. Culture broths were centrifuged at 14,800× g at 4 • C for 10 min, filtered with 0.22 µm regenerated cellulose filters, opportunely diluted with H 2 O/CH 3 CN 0.1% acetic acid solution, and used directly for LC/MS/MS analysis.…”