Exiguobacterium acetylicum from Hentak: A dual-functional strain with probiotic and aroma-enhancing capabilities

Abstract

Background: The present investigation sought to isolate and characterize microbial strains from Hentak, a traditional fermented fish delicacy of Manipur, India, for the evaluation of probiotic and aroma-producing functionalities, with potential application in functional food biotechnology. Results: Thirty-six bacterial isolates were obtained from Hentak and screened for aroma producing and probiotic traits including acid and bile tolerance, auto-aggregation, and adhesion to epithelial cells. The most promising strain was identified through 16S rRNA gene sequencing and phylogenetic analysis. Volatile aroma compounds produced in model fermentations (curd and rice beer) were analyzed using gas chromatography–mass spectrometry (GC–MS). Safety assessment included antibiotic susceptibility and pathogenicity assays. Sensory attributes of fermented products were evaluated using a 10-point hedonic scale. Strain Hentak/NA/5, identified as Exiguobacterium acetylicum FPIH1 (GenBank accession no. PQ471485.1), exhibited strong acid (79.03% survival at pH 2) and bile (88.37% survival at 0.5%) tolerance, 93.5% epithelial adhesion, and 22.87% auto-aggregation. It was non-hemolytic, DNase-negative, and sensitive to tested antibiotics. GC–MS analysis confirmed the production of key volatile compounds such as 1-butanol, oxalic acid, and heptane. Sensory evaluations confirmed enhanced aroma and flavor, with Hentak/NA/5 (Exiguobacterium acetylicum) scoring 8.0 ± 0.86 and 7.0 ± 0.79 for curd and beer, respectively, on a 10-point hedonic scale (p < 0.05). Conclusions: Exiguobacterium acetylicum (Hentak/NA/5) is a novel, multifunctional microbial candidate with both probiotic and aroma-enhancing properties. Its origin from a culturally significant but underexplored fermented product underscores its ecological novelty. The application of the strain as a starter culture can enhance both the sensory and health-promoting qualities of fermented foods, underscoring the microbial richness of traditional ethnic fermentations as reservoirs for food biotechnology innovations.