The natural, non-genetically modified microorganisms used are free to use, listed and classified for a long time by science and state services. Directive 2000/54 / CE1 and the EFB (European Federation of Biotechnologies - CR 12894: 1997) have classified known microorganisms into 5 categories.

The microorganisms used and authorized in biological treatments for pollution control and environmental protection are class 1. This class contains microorganisms, which have never been described as causative agent of diseases in humans and which do not pose a threat to the environment (EFB) and they are free to use, without referring to the competent authority for the protection of workers (directive) article 2.
These microorganisms belong to the same category as those used in food, such as lactobacilli (lactic acid bacteria), bacteria and fungi involved in the fermentation of cheese, acetification bacteria (vinegar, alcohol), etc.