STABLE MICROBIAL TOXINS IN FOOD, FEED AND INDOOR AIR

NEWS ON CEREULIDE, THE EMETIC TOXIN OF BACILLUS CEREUS

Our accumulated data indicates that cereulide may possess higher mammalian cell toxicity than any other microbially produced heat stable toxin known so far. Cereulide has high affinity to K + ions. At blood concentrations of potassium ions (3 to 4 mM K +) cereulide is a more effective potassium ionophore than any other compound described so far. Exposure to cereulide causes in mitochondria loss of the membrane potential, Δφ m, and uncoupling of oxidative phosphorylation.

The spores of cereulide producing strains of B cereus are manyfold more heat resistant than spores of cereulide non-producers. This situation may lead to enrichment of cereulide producers in foods that are (repeatedly) heat treated.

Some key properties of this toxin are compiled (updated: 2007-03-19) in the table below. Read more on this



SPECIFIC, SENSITIVE CHEMICAL ASSAY FOR CEREULIDE

based on multiple specific ions, allows accurate, simultaneous analysis of several peptide toxins in microbes, dust and material samples (Häggblom et al., 2002, Appl Environ Microbiol, 68, 2479-2483, Jääskeläinen et al., J. Food Prot. 2003, 66, 1047-1054.

We determined the acute human toxic dose of cereulide to a healthy adult: 8 μ g / kg b.wt (Jääskeläinen et al.,2003, Toxicology In Vitro, 17, 737-744 )

Chemical assay of cereulide

Chemical assay of cereulide


POTASSIUM CHANNEL FORMING TOXINS FROM MICROBES IN MAN'S ENVIRONMENT

Bacillus amyloliquefaciens is a sporeforming bacillus. Strains from moisture damaged buildings commonly produce large quantities (= several % of cell dry wt) of a small (1197 g/mol) fungicidal peptide, amylosin. It consists of a peptide backbone linked to a polyene tail. It forms potassium and sodium permeant channels mammalian cell membranes and causes collapse of gradients of these ions accross the cell membrane at exposure concentrations of 30 nM. READ MORE ON THIS

Trichoderma harzianum is a mold used as the workhorse of enzyme industry. It also commonly grows indoor in buildings that suffered moisture damages (see image) and produces trichokindlin-like peptaibols that are active in generating potassium ion permeant channels in mammalian cell membranes. (images) READ MORE


About 8 molecules of the the T. harzianum  peptaibols were needed to  highly K+ permeant channel. The peptaibols werehomologs containing (acetyl)amino isobutyric acid, glutamine, valine / isoleucine, alanine, proline and leucinol (terminus) were needed to form a single channel. 100% of the strains tested produced these toxic peptaibols!

Peltola et al, 2004, Appl Env Microbiol, 70(8),4996-5004