EFSA FEEDAP — L-cystine (E. coli DSM 34232) for all animal species
Source: EFSA FEEDAP scientific opinion, EFSA Journal 2025;23(10) (DOI 10.2903/j.efsa.2025.9688), retrieved 2026-08-06 via Europe PMC OA full-text XML. Paraphrase of an EFSA opinion that the source XML tags CC-BY-ND; per project COPYRIGHT_POLICY only facts/numbers/proper-nouns are quoted verbatim, sentences rewritten.
Editorial context (read this before using the data point)
This is the EFSA FEEDAP jurisdiction on the amino-acid feed additive L-cystine (E. coli DSM 34232) — one of four amino-acid safety opinions in this batch (Task L). Read with the efsa nutrient endpoints and AAFCO/FEDIAF amino-acid provisions.
Key findings (paraphrase; numbers and proper nouns verbatim from source)
- Production strain E. coli DSM 34232 harbours two acquired AMR (antimicrobial-resistance) genes, but no viable cells or DNA of the strain were detected in the final product, so the strain raises no safety concern.
- The additive is safe for target species, consumers and the environment at the proposed conditions of use.
- User safety: not a skin/eye irritant and not a skin sensitiser.
- Because L-cystine is used as a flavouring compound in food, the Panel expects a similar function in feed and requires no further efficacy demonstration.
Pet-food relevance
Cystine (the oxidised dimer of cysteine) is relevant to sulphur-amino-acid nutrition in cats and dogs. The explicit AMR-gene disclosure with the 'no viable cells/DNA → no safety concern' resolution is the notable honesty point; the safe-for-all-species conclusion is the usable data point.
Scope note / honest gap
Paraphrase of an EFSA opinion; source XML licence tag was CC-BY-ND, so this topic quotes only data points verbatim and rewrites prose. Full strain-characterisation and tolerance statistics are not reproduced.