Development of Serum-Reduced Medium for Mackerel Muscle Cell Line Cultivation

Serum replacements are crucial for addressing costs, animal welfare, and sustainability concerns in cultivated meat production. This study aimed to develop a serum-reduced medium applicable to the proliferation of the Atlantic mackerel cell line (Mack1) normally grown in L-15 medium-containing 20% fetal bovine serum (FBS). Various protein isolates from nonanimal sources and defined ingredients were screened for their impact on Mack1 cell growth to identify beneficial ingredients and determine optimal concentration ranges. In individual screening over 3 day cultures, protein isolates from rapeseed, chlorella, and spirulina and other ingredients (selenium, insulin, l-ascorbate 2-phosphate, linoleic acid, fibroblast growth factor (FGF)-2, transforming growth factor (TGF)-β1, and oleic acid) improved Mack1 cell growth in serum-reduced conditions (L-15 medium containing 2.5% FBS). These select ingredients as a mixture (M6; insulin, selenium, l-ascorbate 2-phosphate, linoleic acid, FGF-2, TGF-β1) supported Mack1 cell proliferation when added to L-15 medium containing 2.5% FBS. When combined with F-12 medium and rapeseed protein isolate, this formulation supported more than 30 doublings of the mackerel cells over a 55 day period, a significant advance in media development for mackerel cells, providing the groundwork for further optimization toward serum-free conditions.