摘要
This study focused on enhancing the production of gamma-aminobutyric acid(GABA)by Lactiplantibacillus plantarum using ultrasound-assisted fermentation.L.plantarum with high GABA-producing capacity was isolated from Chinese pickles,and the optimized ultrasonic conditions were achieved after 9 h of seed inoculation at 28 kHz for 40 min.Compared with the control,sonication significantly increased the GABA yield by 29.72%(P<0.05).The kinetic model revealed an increase in the maximum viable cell count from 1.42 to 1.63×10^(8)CFU/mL following sonication.Scanning electron microscopy(SEM)revealed bacterial morphological changes,which might have increased the cell surface area.Sonication also increased the activities of adenosine triphosphatase(ATPase)and alkaline phosphatase(AKP),as well as the conductivity of fermentation broth,by 176.8%,21.58%,and 1.57%,respectively.Furthermore,the activity of glycolysis-related enzymes improved significantly after ultrasonic treatment.Images of inverted fluorescence microscopy indicated a substantial increase in the intracellular Ca^(2+)concentration.The 1,6-diphenyl-1,3,5-hexanetriene(DPH)fluorescent probe analysis showed an increase in cell membrane fluidity.Both of the above results were associated with increased membrane permeability.These findings suggest that sonication may increase GABA production by promoting bacterial growth and metabolic activity,as well as improving cell permeability,making it a promising approach to improve the nutritional value of fermented products.
基金
supported by grants from the Primary Research&Development Plan of Jiangsu Province(BE2020329)
sponsored by a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
