Mychonastes homosphaera MHSC24 Isolated from Brackish Waters of Korea: Taxonomic, Physiological, and Biochemical...

Mychonastes homosphaera MHSC24 is a green microalga newly isolated from a brackish coastal site in Korea. This study represents the first indigenous record of this species in the country. It provides a comprehensive characterization of its morphological, molecular, physiological, and biochemical characteristics. This microalga was identified through morphological observations and multilocus phylogenetic analyses. Strain MHSC24 exhibited robust growth under mesophilic temperatures (15-27 °C), moderate light intensities (88-300 μmol photons m^-2 s^-1), and low salinity levels (0-10 PSU). Optimal growth was observed at 27 °C, 193 μmol photons m^-2 s^-1, and 0 PSU. Under standard cultivation, the strain exhibited high protein levels (~54% of dry weight, DW) and accumulated substantial amounts of canthaxanthin (5.59 mg g^-1 DW), the predominant carotenoid in its pigment profile. Thus, MHSC24 is a promising candidate for sustainable protein- and carotenoid-based applications. Palmitic acid (11.95 mg g^-1 DW) and galactose (2.07 mg g^-1 DW) were the predominant fatty acid and monosaccharide, respectively. The physiological resilience, high protein yield, and substantial canthaxanthin accumulation of MHSC24 support its potential utilization in the functional food, feed, and nutraceutical sectors. Therefore, this study provides a basis for optimized cultivation strategies and industrial exploitation of indigenous Korean microalgae.