A type of * biochemical mutant that can grow normally if provided with a supplement in its diet to replace the substance it has lost the ability to make. For example, certain mutants of the mould Neurospora crassa need the amino acid arginine in the culture medium to grow normally (the unmutated mould can synthesize all the amino acids it requires from ammonia). By supplying the auxotrophic mould with various precursors of arginine it can be established which of the enzymes in the pathway to arginine is missing. |
