Scallops belong to the Pectinidae family of the Mollusca phylum and are a major economic shellfish in ocean. With the rapid growth of shellfish aquaculture, the processing size of scallops has also increased significantly. During the processing of scallop, a large amount of scallop byproducts are generated, including the mantle (skirt) and viscera. Glutamic acid (Glu) is a main amino acid in scallops and the substrate for the produce of γ-aminobutyric acid (GABA), which is an important inhibitory neurotransmitter in the central nervous system (CNS). Therefore, finding low-cost raw materials for efficient microbial production of GABA is a key issue to solve the problems of large-scale production and application of food-grade GABA. This study aimed to replace the nutrients in traditional culture media by enzymatic hydrolysis and blending of scallop skirts, which induce lactic acid bacteria to highly express glutamic acid decarboxylase (GAD) to convert Glu into GABA via optimal environmental factors. In addition, the regulatory effect of GABA on the immune activity of macrophages also is to solve the problems of complex preparation processes and high costs of traditional culture media, while increasing the content and edible safety of GABA products. This method provides new insights into the immune regulatory functions of small molecule metabolites in the immune system, in addition to cytokines and membrane proteins. • 0.5% enzyme addition amount and 8 h culture have high yield amino acid content. • pH 4.5, 0.5% glucose, 37°C, and 4 days culture can generate the highest GABA. • GABA fermentation liquid has not cytotoxicity to MC3T3-E1 cells. • The scallop fermentation liquid and GABA enhanced NO production in RAW264.7 cells. • The fermentation liquid and GABA promoted CRP, IL-6,TNFα, and TNFβ produce.
Yang et al. (Sun,) studied this question.