Prototrophs Bacteria that can synthesize all they require from these basic ingredients are called prototrophs(原养型微生物) and most microorganisms that survive in the outside environment can do this Microbes that have become adapted to life in a situation rich with nutrients such as the human body may require other growth factors to be provided, such as vitamins amino acids or nitrogenous bases. these organisms are called auxotrophs(营养缺陷型) Leuconostoc mesenteroides, for exam ple, requires over 40 additional growth factors. Bacterial growth media are therefore designed to suit the organism of interest and may be either defined or com plex media auxotrophsBacteria that can synthesize all they require from these basic ingredients are called prototrophs（原养型微生物） and most microorganisms that survive in the outside environment can do this. Prototrophs Microbes that have become adapted to life in a situation rich with nutrients such as the human body may require other growth factors to be provided, such as vitamins, amino acids or nitrogenous bases. These organisms are called auxotrophs（营养缺陷型）. Leuconostoc mesenterdides, for example, requires over 40 additional growth factors. Bacterial growth media are therefore designed to suit the organism of interest and may be either defined or complex media. auxotrophs