Living bacteria or bacterial spores are undesirable components of bacu
lovirus preparations (e.g. granulosis virus) produced in vivo. This is
also true, at least in Germany, for preparations of Bacillus thuringi
ensis subsp. tenebrionis. Using ultra-high pressure treatment (at a pr
essure of 550-580 MPa and a temperature of 50 degrees C) the concentra
tion of these bacterial contaminants was reduced by up to eight orders
of magnitude. The biocontrol activity of both preparations remained u
nchanged.