The addition of MEM nonessential amino acids to medium can improve growth and the viability of propagating cells in culture while reducing the biosynthetic burden on these cells.  This concentrated supplement allows for efficient addition to media with no risk of dilution of media components. The addition of MEM nonessential amino acids to medium can improve growth and the viability of propagating cells in culture while reducing the biosynthetic burden on these cells.  This concentrated supplement allows for efficient addition to media with no risk of dilution of media components.