Retention of Bacillus cereus and its toxin, cereulide, in cellulosic fibres

Bacillus cereus is the only pathogen that is occasionally found in paper and paper products, but there is no information on its prevalence. The aim of this work was to obtain data for a risk assessment of B. cereus in cellulosic fibre-based products. Handsheets were formed using laboratory papermaking equipment from stocks admixed with B. cereus. Then the distribution of B. cereus and its heat-stable toxin, cereulide, between the fibre web and the wire filtrate was measured. The handsheets retained 5% of the vegetative cells and spores of B. cereus and 10-15% of the cereulide. Transfer of cereulide into food or drink through contact with paper was investigated using ethanol and hot and cold water as food and drink simulants. Less than 0.2% of the cereulide from handsheets was recovered from hot and cold water, as measured by LC/MS and the boar sperm bioassay. Total immersion in 95% v/v ethanol leached nearly all cereulide present in the paper. The results obtained with the bioassay were equivalent to those obtained by LC/MS for the leachates, indicating that cereulide retained its toxicity through the handsheet-making process. The results indicate that cereulide in pulps is probably also present in paper products made from them, but the concentration appears to be too low to be relevant in terms of toxicity.