Botany and Microbiology Department, Faculty of Science, Alexandria University, Alexandria, Egypt.
National Institute of Oceanography and Fisheries, NIOF, Cairo, Egypt.
Probiotics Antimicrob Proteins. 2022 Oct;14(5):934-946. doi: 10.1007/s12602-022-09963-z. Epub 2022 Jun 25.
Psychobiotics are a novel class of probiotics with potential to confer mental wellness via production of neuroactive compounds such as gamma-aminobutyric acid (GABA). The demand for new biological sources of GABA has increased steadily. Therefore, the current study reports the isolation of 17 presumptive lactic acid bacteria (LAB) from marine samples and their screening for GABA synthesis from monosodium glutamate (MSG) using thin-layer chromatography (TLC). The isolate SH9 was selected as a high GABA producing strain. The GABA content of SH9 cell free supernatant (CFS) was quantitatively determined by high performance liquid chromatography (HPLC) to be 0.97 g/L. SH9 was identified biochemically and molecularly as Enterococcus faecium (identity 99%). Moreover, SH9 demonstrated promising probiotic potentials; it gave no signs of hemolysis and could survive at low pH values and high bile salt concentrations. It also exhibited antimicrobial activity against highly pathogenic strains and the ability to grow at 6.5% NaCl. In addition, SH9 CFS showed anti-inflammatory and antioxidant properties. The glutamate decarboxylase (GAD) gene was detected in SH9 by using specific primers. Product of 540 bp was obtained, sequenced, and analyzed (accession number: MW713382). The inferred amino acid sequence was 99.3% identical to Lactobacillus plantarum M-6 gadB gene. The findings of this study suggest that the marine isolate E. faecium SH9 could be used as a novel psychobiotics in the development of GABA rich healthy products.
益生菌是一类新型的益生菌，通过产生神经活性化合物，如γ-氨基丁酸（GABA），具有促进心理健康的潜力。对 GABA 新生物来源的需求稳步增长。因此，本研究从海洋样本中分离出 17 株假定的乳酸菌（LAB），并通过薄层层析（TLC）筛选其从谷氨酸单钠（MSG）合成 GABA。分离株 SH9 被选为高产 GABA 的菌株。通过高效液相色谱（HPLC）定量测定 SH9 无细胞上清液（CFS）中的 GABA 含量为 0.97g/L。通过生化和分子鉴定，SH9 被鉴定为屎肠球菌（同一性为 99%）。此外，SH9 表现出有希望的益生菌潜力；它没有溶血迹象，可以在低 pH 值和高胆汁盐浓度下存活。它还表现出对高致病性菌株的抗菌活性和在 6.5%NaCl 下生长的能力。此外，SH9 CFS 具有抗炎和抗氧化特性。通过使用特异性引物，在 SH9 中检测到谷氨酸脱羧酶（GAD）基因。获得了 540bp 的产物，进行测序和分析（登录号：MW713382）。推导的氨基酸序列与植物乳杆菌 M-6 gadB 基因的 99.3%相同。本研究的结果表明，海洋分离屎肠球菌 SH9 可作为 GABA 丰富的健康产品开发的新型益生菌。
