What are the mutants that cannot grow on minimal medium and requires nutrient supplements called?

Auxotrophs would be the mutant cells that are not capable of utilizing certain nutrients or synthesizing certain compounds. Auxotroph is a mutant that requires nutritive(s) not needed by the wild type (prototroph). Auxotrophic mutations have been extensively used for the study of biochemical pathways and for the identification enzymes catalyzing particular metabolic steps. In the example of bacteria capable of utilizing lactose as a nutrient source, the ability to lactose is denoted by lac⁺ and the inability to utilize lactose is denoted lac^-.