Marine sediments represent a rich yet underexplored reservoir of pigment-producing microorganisms with significant biotechnological potential. In the present study, marine-derived Exiguobacterium species were isolated from coastal sediment samples collected from the Bay of Bengal, Bangladesh, and investigated as novel sources of bioactive carotenoid pigments. Among the recovered chromogenic bacteria, two intensely orange pigment–producing isolates were selected and identified through 16 S rRNA gene sequencing as Exiguobacterium arabatum BDIFST240023 and Exiguobacterium qingdaonense BDIFST240024. Intracellular pigments were extracted using methanol and partially purified by silica gel chromatography. Physicochemical characterization using UV–Visible spectroscopy revealed characteristic carotenoid absorption maxima near 400 nm, while FTIR analysis confirmed the presence of functional groups consistent with conjugated polyene carotenoid structures. Scanning electron microscopy further demonstrated aggregated, crystalline pigment morphologies. The biological activities of the extracted pigments were systematically evaluated. Both pigments exhibited concentration-dependent antibacterial activity, with pronounced inhibitory effects against Gram-positive pathogens and comparatively lower efficacy against Gram-negative bacteria. Additionally, the pigments demonstrated notable antioxidant capacity in DPPH radical scavenging assays. Cytotoxicity assessment using Vero cell lines indicated moderate, dose-dependent effects, with LD₅₀ values exceeding 45 µg/mL, suggesting acceptable preliminary safety profiles. Collectively, this study highlights marine-derived Exiguobacterium spp. from Bay of Bengal sediments as promising and previously unreported sources of bioactive carotenoid pigments. The combined physicochemical stability, antimicrobial and antioxidant activities, and moderate cytotoxicity underscore their potential for future applications in food, nutraceutical, and biomedical industries, while also emphasizing the biotechnological value of marine sediment–associated microbial diversity..

https://doi.org/10.1007/s41208-026-01104-5