While a considerable amount of data on the effect of single
and combined treatments and storage conditions on spore
germination, outgrowth, and overall growth of C. botulinum
strains are available [10,13,17,18], reports on the effect of
successive treatments on stress resistance are lacking.
Increased robustness towards successive treatments arising
from mild treatments is a known phenomenon in several
Gram-positive bacteria [15,33e37]; thus, this effect should be
investigated in more detail in C. botulinum.