Zareian Mohsen, Ebrahimpour Afshin, Bakar Fatimah Abu, Mohamed Abdul Karim Sabo, Forghani Bita, Ab-Kadir Mohd Safuan B, Saari Nazamid
Faculty of Food Science and Technology, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia.
Int J Mol Sci. 2012;13(5):5482-5497. doi: 10.3390/ijms13055482. Epub 2012 May 7.
l-glutamaic acid is the principal excitatory neurotransmitter in the brain and an important intermediate in metabolism. In the present study, lactic acid bacteria (218) were isolated from six different fermented foods as potent sources of glutamic acid producers. The presumptive bacteria were tested for their ability to synthesize glutamic acid. Out of the 35 strains showing this capability, strain MNZ was determined as the highest glutamic-acid producer. Identification tests including 16S rRNA gene sequencing and sugar assimilation ability identified the strain MNZ as Lactobacillus plantarum. The characteristics of this microorganism related to its glutamic acid-producing ability, growth rate, glucose consumption and pH profile were studied. Results revealed that glutamic acid was formed inside the cell and excreted into the extracellular medium. Glutamic acid production was found to be growth-associated and glucose significantly enhanced glutamic acid production (1.032 mmol/L) compared to other carbon sources. A concentration of 0.7% ammonium nitrate as a nitrogen source effectively enhanced glutamic acid production. To the best of our knowledge this is the first report of glutamic acid production by lactic acid bacteria. The results of this study can be further applied for developing functional foods enriched in glutamic acid and subsequently γ-amino butyric acid (GABA) as a bioactive compound.
L-谷氨酸是大脑中的主要兴奋性神经递质，也是新陈代谢中的重要中间体。在本研究中，从六种不同的发酵食品中分离出218株乳酸菌，作为谷氨酸生产者的潜在来源。对推定的细菌进行了合成谷氨酸能力的测试。在显示出这种能力的35株菌株中，MNZ菌株被确定为谷氨酸产量最高的菌株。包括16S rRNA基因测序和糖同化能力在内的鉴定测试将MNZ菌株鉴定为植物乳杆菌。研究了这种微生物与其谷氨酸生产能力、生长速率、葡萄糖消耗和pH值分布相关的特性。结果表明，谷氨酸在细胞内形成并分泌到细胞外培养基中。发现谷氨酸的产生与生长相关，与其他碳源相比，葡萄糖显著提高了谷氨酸的产量（1.032 mmol/L）。0.7%的硝酸铵浓度作为氮源有效地提高了谷氨酸的产量。据我们所知，这是关于乳酸菌产生谷氨酸的首次报道。本研究结果可进一步应用于开发富含谷氨酸以及随后作为生物活性化合物的γ-氨基丁酸（GABA）的功能性食品。
