Contrasting Growth On Different Peptones

Seven strains of bacteria were isolated in two laboratories in North East England on a medium containing Oxoid Peptone L37, but not on other media. Four of them produced relatively few viable cells in Evans Peptone water. However, this peptone could be modified by growing in it aerobic spore-bearing bacilli isolated from either Oxoid Peptone or Difco Proteose Peptone no. 3. After preconditioning Evans Peptone yielded as many cells as Oxoid Peptone.