Isolation and characterization of lactic acid bacteria from '‘Pakkat su’'− A traditional fermented vegetable (Brassica juncea) of the Tai Phake community in Assam

The efficacy of probiotic microorganisms derived from indigenous fermented foods is often population-specific, influenced by factors such as raw material variability, preparation methods, host–microbial interactions, and native gut microbiota composition. This study aimed to isolate and evaluate the probiotic potential of lactic acid bacteria (LAB) from ‘Pakkat su’ , a Brassica juncea (L.) Czern (Brassicaceae) based, traditional fermented food consumed by the Tai Phake community in Assam, India. A total of 29 LAB isolates were obtained and subjected to in vitro screening for key probiotic traits, including acid and bile tolerance, bile salt hydrolysis, antibiotic resistance, antimicrobial and hemolytic activity, and cell surface characteristics. Among these, three isolates—TPI-4, TPI-7, and TPI-9—exhibited high tolerance to acidic pH and bile salts, and were non-hemolytic. These isolates demonstrated strong antagonistic activity against Escherichia coli ATCC-10536 and Staphylococcus aureus ATCC-BAA-1026, with TPI-9 showing the highest zone of inhibition (1.6 cm) against S. aureus and TPI-7 showing 1.3 cm against E. coli . TPI-9 also exhibited the highest hydrophobicity (76 %) and auto-aggregation ability (80 %). Molecular identification using 16S rRNA gene sequencing revealed the isolates as Lactiplantibacillus plantarum TPAB1, Lacticaseibacillus casei TPMR2, and Lactiplantibacillus pentosus TPMS3. These findings suggest that selected LAB isolates from Pakkat su hold significant promise as probiotic candidates, warranting further investigation for potential use in functional food or therapeutic applications. This study provides the first comprehensive probiotic characterization of LAB isolated from Pakkat su , a culturally unique fermented food of the Tai-Phake community, thereby expanding the microbial biodiversity knowledge of Northeast Indian fermented vegetables • Three probiotic bacterial strains were isolated from ‘ Pakkat su ’, a traditional fermented food of the Tai-Phake community • Isolates TPI-4, TPI-7 and TPI-9 were identified as L. plantarum TPAB1, L. casei TPMR2 and L. pentosus TPMS3 by 16S rRNA • GenBank IDs OQ996876, OQ997380, OQ998330 correspond to 16S rRNA of L. plantarum TPAB1, L. casei TPMR2 , L. pentosus TPMS3 • L. casei TPMR2 inhibited E. coli ATCC10536, while L. pentosus TPMS3 showed strongest inhibition of S. aureus ATCC1026