Optimization and Partial Characterization of Biopigment Production from Endophytic Mesobacillus subterraneus SGL and...

In recent years, the multitude of advantages that natural pigments offer over synthetic pigments has opened up intriguing avenues for diverse applications across numerous sectors. Bacteria are a preferable source of biocolorants, as they can produce large amounts in a short time and without seasonal constraints, making them appear safe and biodegradable. Among them, endosymbiotic bacteria that coexist with plants might serve as an alternative source for the synthesis of several unique bioactives with distinctive medicinal properties. In view of this, the primary objective of the current research was directed towards the isolation and identification of seagrass-associated pigmented bacteria, the extraction and characterization of the pigment using Ultraviolet-visible spectrophotometry, followed by Fourier transform infrared spectroscopy, as well as studying the biological characteristics of the pigment. Among 13 distinct bacterial colonies, an orange-red pigment-producing endophyte was identified as Mesobacillus subterraneus SGL, employing morphological features and phylogenetic characterization by 16S rRNA sequencing. After screening appropriate media for pigment production, the physiochemical parameters (temperature, pH, incubation period, inoculum percentage, agitation, nitrogen, and carbon sources) affecting the pigmentation bioprocess were refined through a stepwise optimization approach. The pigment synthesized by the isolate was extracted using methanol, and different spectroscopic analysis revealed that the extracted pigment might be a carotenoid. In vitro bioactivity studies demonstrated that the extracted pigment exhibited 79.36 ± 0.89% of antioxidant potential and displayed a notable antimicrobial effect against the tested pathogens.

The online version contains supplementary material available at 10.1007/s12088-025-01498-5.