Choice of Inspect/Plant Spiroplasma Species for NAT Validation
Following the introduction of a revised EP2.6.7 MYCOPLASMAS (EuPharm 12.2) in April 2026, where in 4.3 VALIDATION, it now specifies the use of S. citri or another species for the Spiroplasma genus. Mycoplasma Experience will use and recommends Spiroplasma melliferum for the following reasons:-
1. Originally isolated from the haemolymph and gut of honey bees, it has also been isolated from a variety of insects and plant surfaces (Clarke, T.B et al. 1985. Int J Syst Bacteriol. 35:3:296-
2. S. melliferum has been isolated from mammalian cell cultures, both research and from a commercial bioreactor (Windsor, H.M & English, C. 2021. J. Biologicals. 71:48-
3. Spiroplasma citri has previously been recommended as a Test Organism where there is exposure to plant or insect material during production but it has several disadvantages both for its use and relevance as a potential contaminant.
4. S. citri is a specific citrus pathogen with specific insect vectors therefore is unlikely to be a contamination risk for the majority of plant/insect exposures.
5. S. citri does not grow at incubation temperatures used for mammalian or avian cells, it requires incubation at 32°C or less.
Therefore, the risk of contamination with S. melliferum is much greater than with S. citri and extends across a broader incubation temperature range.
Mycoplasma Experience is already using S. melliferum to validate media for our Low Temperature Cell Culture Test protocols and alongside Acholeplasma laidlawii for EP 2.6.7, where Test Articles may be at risk of environmental contamination.
In addition, S. melliferum grows more rapidly than S. citri allowing faster release of media lot, including where used at the lower temperatures required for insect cell cultures, such as Sf9 and, due to the close genetic relationship with S. citri, a PCR successfully validated with S. melliferum should also detect S. citri DNA.
Mycoplasma Experience Ltd. Phone: 01883 740185 Email: mexp@mycoplasma-