Biochemical and nutritional composition analysis of selected seaweed cultivated through in-vitro thallus regeneration process

• Four seaweed species were cultured via in-vitro thallus regeneration process. • U. intestinalis showed the highest biomass yield and growth rate. • G. tenuistipitata possess superior nutrients and antioxidant activity. • Ulva spp. were protein-rich, suitable for aquafeed and biomass production. The production of seaweed seedlings is crucial in Bangladesh for the advancement of land-based cultivation. Therefore, this study assessed the growth performance, biochemical, and nutritional profiles of four seaweed species, i.e., Ulva intestinalis, Ulva lactuca, Caulerpa racemosa , and Gracilaria tenuistipitata , cultivated via the fragment regeneration method. U. intestinalis showed the highest daily growth rate (8.77 %/day) and biomass yield (578 g), followed by U. lactuca, G. tenuistipitata , and C. racemosa. G. tenuistipitata had more carbohydrates (64.51 %), calcium (218.20 mg/100 g), iron (155.30 mg/100 g), zinc (6.24 mg/100 g), total phenolic content (76.89 mg GAE g -1 ), and antioxidant activity (DPPH: 47.25 %; IC 50 : 15.11 mg/mL), which shows that it has a lot of potential as a nutraceutical. Green seaweeds ( Ulva spp.) had more protein (18–20 %) and grew quickly, making them suitable for large-scale biomass applications. C. racemosa grew more slowly but had more sucrose, which is useful for goods that are heavy in carbohydrates. Therefore, our current study shows that U. intestinalis and U. lactuca are suitable for rapid biomass production, while G. tenuistipitata shows strong potential as a functional food ingredient due to its high antioxidant and nutrient content.