Isolation of Lactic Acid Bacteria from Cassava Tapai (Manihot esculenta) and Evaluation of Serotonergic Activity for Potential Antidepressant Using ELISA

Background: Lactic acid bacteria (LAB) are microorganisms found in fermented foods and have the potential to produce bioactive metabolites associated with the gut-brain axis. Cassava tapai is a traditional fermented food that may serve as a source of LAB with serotonergic activity. Aim: This study aimed to isolate and identify LAB from cassava tapai and evaluate their serotonergic activity as a potential antidepressant using Enzyme-Linked Immunosorbent Assay (ELISA). Methods: A laboratory experimental study was conducted in vitro. LAB were isolated from cassava tapai using de Man-Rogosa-Sharpe Agar and identified based on colony morphology, Gram staining, and catalase testing. Six isolates were subsequently cultured in de Man-Rogosa-Sharpe Broth, and the supernatants were analyzed using a serotonin ELISA at 450 nm. Statistical analysis was performed using Welch’s t-test. Result: The results show that six LAB isolates, B1A, B2A, B3A, B4B, B5B, and B6B, exhibit Gram-positive, bacillary and coccobacillary morphology and negative catalase reactions. All isolates show a decrease in medium pH from 6 to 4 after incubation. Serotonin levels in the isolate group range from 10.903 to 33.952 ng/mL, whereas the control ranges from 0.195 to 2.210 ng/mL. The mean serotonin level in the isolate group is 21.47 ± 9.59 ng/mL, higher than the control at 1.23 ± 1.01 ng/mL, with a significant difference (p=0.0033). Conclusion: LAB isolates from cassava tapai show serotonergic activity in vitro and have potential for further investigation regarding antidepressant activity.