1. Light sensitive
When a quality control shows less growth on the DRBC plates than expected, it can happen that the DRBC plates have been in the light for too long. When DRBC is exposed to light this will result in the formulation of inhibitory compounds. Therefore keep the DRBC media in a dark and cool place until used.
In particular, CRM-SCE.00085MM will give inhibited growth when DRBC plates are exposed to light for too long.
2. Colony appearance of CRM-PAU on different DRBC suppliers
The mould colonies appearances of CRM-PAU on DRBC can vary from supplier to supplier. Sometimes sporulation hasn’t started yet.
3. Colony appearance on one DRBC batch of medium
It is also possible that different colony forms can be observed in one batch of DRBC, while the plates have been inoculated at the same time. The first DRBC plates (#009) of a batch show sporulation after 5 days, while later filled plates (#949) in the batch does not yet show sporulation.