AUTHOR=Bora Sudipta Sankar , Dullah Samim , Dey Kuntal Kumar , Hazarika Dibya Jyoti , Sarmah Unmona , Sharma Darshana , Goswami Gunajit , Singh Naorem Romen , Barooah Madhumita 

TITLE=Additive-induced pH determines bacterial community composition and metabolome in traditional mustard seed fermented products

JOURNAL=Frontiers in Sustainable Food Systems

VOLUME=6

YEAR=2022

URL=https://www.frontiersin.org/journals/sustainable-food-systems/articles/10.3389/fsufs.2022.1006573

DOI=10.3389/fsufs.2022.1006573

ISSN=2571-581X

ABSTRACT=<sec><title>Introduction</title><p><italic>Kahudi</italic> and <italic>Kharoli</italic> are unique naturally fermented mustard seed products prepared and consumed in the northeastern region of India. The pre-fermentation processing of mustard seeds (soaking, pan-frying, mixing with alkaline or acidic additives, airtight packaging) renders a stringent fermentation environment. The metabolic activities of fermenting bacterial populations yield a myriad of glucosinolate-derived bioactive components which have not been described earlier.</p></sec><sec><title>Methods</title><p>This present study employed integrated 16S rRNA amplicon sequencing and LC-MS-based metabolomics to elucidate the bacterial diversity and metabolome of the two fermented mustard seed food products.</p></sec><sec><title>Results and Discussion</title><p>Univariate and multivariate analyses of metabolomics data revealed differential abundances of a few therapeutically-important metabolites <italic>viz.</italic>, sinapine, indole-3-carbinol, γ-linolenic acid in <italic>Kahudi</italic>, and metabolites <italic>viz.</italic>, β-sitosterol acetate, 3-butylene glucosinolate, erucic acid in <italic>Kharoli</italic>. A metagenomic investigation involving the 16S rRNA (V3–V4) amplicon sequencing showed the dominance of Firmicutes (99.1 ± 0.18%) in <italic>Kahudi</italic>, and Firmicutes (79.6 ± 1.92%) and Proteobacteria (20.37 ± 1.94%) in <italic>Kharoli</italic>. The most abundant genera were <italic>Bacillus</italic> (88.7 ± 1.67% in <italic>Kahudi</italic>; 12.5 ± 1.75% in <italic>Kharoli</italic>) followed by <italic>Lysinibacillus</italic> (67.1 ± 2.37% in <italic>Kharoli</italic>; 10.4 ± 1.74% in <italic>Kahudi</italic>). Members of both these genera are well known for proteolytic and endospore-forming abilities which could have helped in colonizing and thriving in the stringent fermentation environments.</p></sec>