Opinion of Advocate General Kokott delivered on 17 October 2019.#Darie BV v Staatssecretaris van Infrastructuur en Milieu.#Request for a preliminary ruling from the College van Beroep voor het Bedrijfsleven.#Reference for a preliminary ruling — Regulation (EU) No 528/2012 — Article 3(1)(a) and (c) — Concept of ‘biocidal product’ — Concept of ‘active substance’ — Bacterial product containing the bacterial species Bacillus ferment — Mode of action other than mere physical or mechanical action — Indirect action — Period within which effect takes place.#Case C-592/18.