Metabolites from subsp. : Isolation, Structure Elucidation, and Antimicrobial Activity.

Herein, we disclose the identification of novel metabolites from a potential probiotic strain, subsp. obtained from traditional dairy milk samples collected in Maharashtra, India (in January 2021). Isolated metabolites include pyrazin-2-carboxamide [, pyrazinamide, a potential antitubercular drug], 3,5-dihydroxy-6-methyl-2,3-dihydro-4-pyran-4-one (, DDMP), 2,4-di--butylphenol (), and hexadecanoic acid (, palmitic acid). The chemical structures of these metabolites were elucidated through extensive 1D NMR (H and C) and 2D NMR (HSQC, HMBC, and NOESY) analyses, high-resolution mass spectrometry, high-performance liquid chromatography, and single-crystal X-ray crystallography. Furthermore, these novel metabolites exhibited potent inhibitory activities against various bacteria, fungi, and yeast strains with minimum inhibitory concentrations ranging between 1.56 and 25 μg/mL, and compounds and were found to be most active against a wide range of microbial strains tested.