Growth factor Growth factor is a kind of organic material can't be self synthesized by auxotrophs(营养缺陷型微生物) with simple carbon source and nitrogen source, while is necessary for microorganisms to regulate the normal metabolism. Although growth factor is an important nutrient element it is differentfrom the carbon source energy source and nitrogen, source in that not any certain organism need the growth factor provided by the enyironment.Growth factor Growth factor is a kind of organic material can’t be self - synthesized by auxotrophs(营养缺陷型微生物) with simple carbon source and nitrogen source, while is necessary for microorganisms to regulate the normal metabolism. Although growth factor is an important nutrient element, it is different from the carbon source , energy source and nitrogen source in that not any certain organism need the growth factor provided by the environment