Portable Photobioreactor‐Based Stock Culture of <i>Skeletonema costatum</i> for Sustainable Live Feed Production in Shrimp Hatcheries of Bangladesh

ABSTRACT In Bangladesh's shrimp ( Penaeus monodon ) hatcheries, the live cells of Skeletonema costatum are used as post larvae (PL) diet for rearing. In hatcheries’ microalgae culture systems, the contamination of initial algae stock was found to be a common phenomenon through a previous study, which ultimately results in shrimp PL production loss. In this study, an optimized portable photobioreactor (PBR) model was developed for the S. costatum pure stock maintenance. A 3 ft × 3 ft PBR system with nine separate culture jars has been developed, which possesses an auto‐temperature‐controlled system using controlled‐temperature water flow. The physicochemical parameters, that is, salinity, temperature and pH, were optimized for S. costatum culture using response surface methodology in the function of Box–Behnken design for maximizing the cell density and culture period. The f/2 Guillard's medium was used as culture medium for S. costatum culture in the PBR system. A total of 17 experiments were conducted to analyse the optimum conditions of the selected three parameters. According to the desirability parameters run of the model, a 27°C temperature, 29 ppt salinity and a pH of 8.4 produced the maximal cell density of 5.333 × 10 5 cells/mL at Day 4. Under these optimal conditions, S. costatum produced 43.80% ± 1.32% protein, 19.60% ± 1.29% lipid and 21.58% ± 0.92% carbohydrate. In addition, S. costatum synthesized 43.70% essential amino acids in its dried biomass, where a total of 16 amino acids were reported. The fatty acid profile showed 75.31% monounsaturated fatty acids, 4.76% omega‐6 fatty acids, 2.17% omega‐3 fatty acids and 6.93% polyunsaturated fatty acids. This optimized PBR model will be a practical and scalable solution to ensure pure live feed stock at shrimp hatchery practices.