5.5.1 General remarks 

As expressly stated in Art. 53(b), second clause, the exception referred to in the first clause does not apply to microbiological processes or their products.

"Microbiological process" means any process involving or performed on or resulting in microbiological material. The term "microbiological process" is to be interpreted as covering not only processes performed on microbiological material or resulting in such material, e.g. by genetic engineering, but also processes which as claimed include both microbiological and non-microbiological steps.

The product of a microbiological process may also be patentable per se (product claim). Propagation of the microorganism itself is to be construed as a microbiological process for the purposes of Art. 53(b). Consequently, the microorganism can be protected per se as it is a product obtained by a microbiological process (see G‑II, 3.1). The term "microorganism" includes bacteria and other generally unicellular organisms with dimensions beneath the limits of vision which can be propagated and manipulated in a laboratory (see T 356/93), including plasmids and viruses and unicellular fungi (including yeasts), algae, protozoa and, moreover, human, animal and plant cells. Isolated plant or animal cells or in vitro plant or animal cell cultures are treated as microorganisms, since cells are comparable to unicellular organisms (G 1/98, Reasons 5.2).

On the other hand, product claims for plant or animal varieties cannot be allowed even if the variety is produced by means of a microbiological process (Rule 27(c)). The exception to patentability in Art. 53(b), first clause, applies to plant varieties irrespective of how they are produced.

However, plant cells or tissues are usually totipotent and able to regenerate the full plant. Therefore, even if plant cells or cell cultures may be regarded as the product of a microbiological process, plant material which is able to propagate the full plant is excluded from patentability if the plant from which the material originates has been exclusively produced by an essentially biological process (G 3/19) (for the meaning of the term "exclusively" in relation, for example, to offspring of transgenic organisms or mutants, see G‑II, 5.4). This exclusion does not apply to patents granted before 1 July 2017 or to pending patent applications with a date of filing date and/or a priority date before then (see G 3/19, XXIX).