The wildtype B. cereus reference strains for Nhe, Hbl and CytK productions were
designated MHI 1491, MHI 1505 and MHI 1307 in this work (1, 2). MHI means B. cereus
strain collection of the Chair of Hygiene and Technology of Milk, LMU Munich.
Caseinhydrolysat-Glucose-Yeast (CGY) medium plus 1% glucose was used for the toxin
production according to the previous publication (3). Briefly, a single colony of B. cereus
on the overnight cultured blood agar was inoculated into 20 mL CGY medium containing
1% glucose, then cultured in water bath for 17 h at 32 °C, subsequently transferred 0.1 mL
of the culture liquid into a new 20 mL CGY medium containing 1% glucose for another 6
h incubation at 32 °C. 200 µL 0.1 M EDTA was added to the final concentration 1 mM
before the harvest of toxin supernatants. The mixture was collected by centrifugation at 3
000 g for 20 min, at 4 °C, then passed through 0.22 µm Millipore filter to get bacteria-free
supernatants for the further use