Cytotoxicity tests

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Why?

The possible toxicity of a microbial strain is usually assessed based on a literature search and on the whole genome sequence. The presence of genes that encode virulence factors may trigger further phenotypic testing.

Biosafe

For Bacillus species, a specific cytotoxicity test is performed to determine if the particular strain produces high levels of non-ribosomally synthesised peptides; this is one of the qualifications of the QPS approach.

The use of strains belonging to the Bacillus cereus group is not advisable in food or feed applications.

How?

Biosafe performs in vitro cytotoxicity tests with Vero cells, as recommended by EFSA.

The release of lactate dehydrogenase (LDH) is used as a marker of plasma membrane disruption caused by toxins. Culture supernatants are used as samples. For this, the customer is instructed to send cell-free culture supernatants from three independent fermentation batches as well as culture medium to be used as a control. Exceptionally, the supernatant can be prepared at Biosafe by making a small-scale culture in the laboratory. EFSA has given guidance for the preparation of the supernatant samples.

Other tests

In addition to the LDH release assay, Biosafe has other in vitro toxicity tests, which can be used for various samples. These include, for example, the boar spermatozoan motility inhibition test or the Highest Tolerated Dose test (HTD). The TPC (total protein concentration) test can be used to assess acute cytotoxicity. Some of the microbial testing available at Biosafe are specifically designed for the safety assessment of food contact materials.