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.

Save 1 000 € on each cytotoxicity test in July

This July we are offering a discount of 1 000 € on each cytotoxicity test. If you order your tests in July and send your Bacillus supernatant samples in August, you will qualify for the discount and get the results by September 13th.

Schedule: Samples should arrive at Biosafe as follows: strain(s) on the commencing week 31 and the supernatant samples on week 34. Test on week 35.
Samples: Viable test strain OR the test strains' supernatant samples in triplicate (6h cultivation in BHI broth, at 30 degrees °C) and the BHI broth as the negative control in duplicate. The negative control should be cultivated in similar conditions as test strain's supernatant samples.*

*If the strain is sent instead of supernatants, the strain will be cultivated on trypticase soy agar (TSA) before the analysis. If the strain needs to be cultivated on another medium, it will be invoiced separately (500-1200 €, depending on the used plate type).