Technical equivalence of microorganisms: need for a GD

Last June 2013 in Sweden the OECD/KEMI/EU workshop on microbial pesticides took place and recently OECD published the relative report.

During the workshop several issues have been dealt with such as the equivalence assessment of the microbial technical materials. Since the approval of an active substance in the EU framework refers to the strain level, the genetic identification is deemed to be the proper tool to distinguish among the strains.

Provided that a same strain is taken into account can we talk about the same phenotype when a different manufacturing process or site occur so that technical equivalence needs to be assessed?

Phenotype is the set of the overall features owned by the microorganisms i.e. development and physiological properties as well as behavior. Phenotype derives from the interactions between the gene expression and the environment in which microorganisms live, affecting as a result the mode of action and the unique properties of each strain relating in particular to safety and efficacy.

The efficacy and safety parameters to be checked in the equivalence assessment are the contents of the active substance, the relevant metabolites and the microbial contaminants. The potential output of the secondary metabolites and toxins, whose toxicity is often unknown, is an open issue for the safety evaluation. Their production infact is not linked to the growth, development and reproduction of the microorganims but it’s a time limited response under stress conditions. Furthermore, the validation of the methods used for the microorganism identification and those for the determination of the microbial contaminants, which should be the ones internationally accepted for food market, are still subject for discussion and need to be clarified in the next future. It would be useful, before introducing a guidance document on the equivalence assessment, to edit a guidance document stating how the reference parameters for the evaluation can be produced reliably and uniquely. Once the comparative parameters have been set, it will be possible to define also the significant changes that result in a different profile of toxicity and efficacy compared with the reference source hence a new risk assessment is required.


Microorganismi