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

Endpoint summary

Additional information

Short-term toxicity to fish

The acute toxicities of L-threonine mother liquor and modified waste (used microbiological material) to Poecilia reticulata were investigated in studies conducted according to a national standard method. In respect to L-threonine mother liquor and modified waste a 48 h LC50=105 mL/L and a 96 h LC50=39.57 mL/L (nominal each) were determined, respectively. In a further study conducted according to OECD Guideline 203, a 96 h LC50>100 mg/L (nominal) was found for the same fish species using modified waste.

The acute toxicity 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) towards Danio rerio was investigated in a study conducted according to OECD Guideline 203 (Fish, Acute Toxicity Test) under semi-static conditions. Fish were exposed for 96 h to measured Biofert Plusz concentrations ranging from 222 to 3861 mg fresh weight/L, equivalent to 62.3 -1085 mg dry matter/L. Analytical monitoring of test material concentration was performed by HPLC and quantification of the main component (L-threonine). The 96 h LC50 was determined to be 738 mg dry matter/L (effective).

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).

Long-term toxicity to fish

Experimental results are not available.

In Annex IX of Regulation (EC) No 1907/2006, it is laid down that chronic fish toxicity tests shall be proposed by the registrant if the chemical safety assessment indicates the need to investigate further the effects on fish. According to Annex I of this regulation, the chemical safety assessment triggers further action when the substance or the preparation meets the criteria for classification as dangerous according to Directive 67/548/EEC orDirective 1999/45/EC or is assessed to be a PBT or vPvB. The hazard assessment of L-threonine mother liquor reveals neither a need to classify the substance as dangerous for the environment, nor is it a PBTor vPvB substance, nor are there any further indications that the substance may be hazardous to aquatic organisms. According to reliable study results, L-threonine mother liquor is considered to be rapidly degraded in the environment and the bioaccumulation potential is regarded to be insignificant. Moreover, the amino acid threonine as the main constituent, is an essential protein constituent in living organisms and so no metabolites are expected to occur that pose a significant risk to living organisms. Therefore, the performance of a chronic fish study is assumed to be scientifically not justifiable.

Short-term toxicity to aquatic invertebrates

The acute toxicity of L-threonine mother liquor and modified waste (used microbiological material) to Daphnia magna was investigated in studies conducted according to a national guideline. The 48 h EC50 values were determined to be comparable (L-threonine mother liquor: 48 h EC50=14 mL/L; modified waste: 48 h EC50=11.61 mL/L nominal each).

The acute toxicity 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) towards Daphnia magna was investigated in a study conducted according to OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test). 20 daphnids (5 daphnids/replicate) were exposed to Biofert Plusz for 48 h at nominal concentrations ranging from 469 to 3559 mg/L under semi-static conditions. The test material concentration was determined by HPLC based on L-threonine (main component) measurements. The 48 h EC50 was determined to be 2410 mg fresh material/L, corresponding to 677 mg dry matter/L (nominal). Moreover, a 48 h NOEC=444 mg dry matter/L and a LOEC=667 mg dry matter/L were found. All concentrations in terms of fresh weight. On a dry weight basis the EC50 is 677 mg/L, The NOEC is 444 mg/L and the LOEC is 667 mg/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).

Long-term toxicity to aquatic invertebrates

Experimental results are not available.

In Annex IX of Regulation (EC) No 1907/2006, it is laid down that chronic toxicity tests with invertebrates shall be proposed by the registrant if the chemical safety assessment indicates the need to investigate further the effects on invertebrates. According to Annex I of this regulation, the chemical safety assessment triggers further action when the substance or the preparation meets the criteria for classification as dangerous according to Directive 67/548/EEC orDirective 1999/45/EC or is assessed to be a PBT or vPvB. The hazard assessment of

L-threonine mother liquor reveals neither a need to classify the substance as dangerous for the environment, nor is it aPBTor vPvB substance, nor are there any further indications that the substance may be hazardous to aquatic organisms. According to reliable study results, L-threonine mother liquor is considered to be rapidly degraded in the environment and the bioaccumulation potential is regarded to be insignificant. Moreover, the amino acid threonine as the main constituent, is an essential protein constituent in living organisms and so no metabolites are expected to occur that pose a significant risk to living organisms. Therefore, the performance of a long-term toxicity study with invertebrates is assumed to be scientifically not justifiable.

Toxicity to algae and cyanobacteria

The toxicity of L-threonine mother liquor and modified waste (used microbiological material) to Scenedesmus quadricauda was investigated in studies conducted according to a national guideline. The 72 h EC50 values were determined to be comparable (L-threonine mother liquor: 72 h EC50=13.5 mL/L; modified waste: 48 h EC50=13.36 mL/L nominal each).

The toxicity 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) towards the unicellular green alga Desmodesmus subspicatus was investigated in a study conducted according to OECD Guideline 201 (Alga, Growth Inhibition Test). Cultures of Desmodesmus subspicatus were exposed to 5 Biofert Plusz concentrations ranging from 339 to 3559 mg/L test material (nominal) corresponding to geometric mean measured concentrations ranging from 126 to 1579 mg/L test material. The concentration of the main component of Biofert Plusz L-threonine was determined by HPLC/UV. Based on geometric mean measured concentrations the 72 h ErC50 and 72 h EyC50 were determined to be 528 and 254 mg fresh material/L, respectively, corresponding to 148 (ErC50) and 71.4 mg dry matter/L (EyC50).

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).

Toxicity to microorganisms

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).