Supernatant from the crystallisation of L-threonine from the broth filtrate from the fermentative production of L-threonine

Toxicity to microorganisms

Description of key information

Based on the results obtained in studies conducted according to OECD Guideline 209 (Biofert Plusz) and a national guideline (L-threonine mother liquor and modified waste), respectively, a 3 h IC0=1000 mg dry matter/L found for Biofert Plusz with activated sludge as test organism can be regarded as worst case for the toxicity of L-threonine mother liquor.

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:

1 000 mg/L

Additional information

The toxicity of L-threonine mother liquor and modified waste (used microbiological material) to Photobacterium phosphoreum was investigated in studies conducted according to a national guideline. The 30 min EC50 was determined to be 11.6 mL/L (L-threonine mother liquor) and 27.9 mL/L (modified waste; nominal each).

The respiration inhibition of Biofert Plusz (mixture of L-threonine mother liquor and L-threonine biomass; L-threonine biomass is also named as modified waste (used microbial material sterilized), mortified biomass, mortified biomass of E. coli (K12), biomass concentrate of threonine production stem) was investigated in a study conducted according to OECD Guideline 209. Non-adapted activated sludge was exposed to a Biofert Plusz concentration of 3560 mg/L nominal for 3 h under static conditions. Biofert Plusz was found to be not toxic to activated sludge at the concentration tested (3 h IC0=3560 mg/L nominal; corresponding to 1000 mg test material dry matter/L).

In conclusion of the available data, it can be assumed that the result obtained with Biofert Plusz represents a worst case situation for the test material under investigation (L-threonine mother liquor).