L-threonine, fermentation products byproduct

Endpoint summary

Additional information

The residue of L-Threonine fermentation is named Biofert Plusz and is grouped into the class of UVCB-substances. The aqueous suspension contains deactivated E.coli K12 biomass, amino acids and residual fermentation nutrients. The freeze-dried product is a brown powder at standard conditions. The melting point of Biofert Plusz was investigated in a study conducted according to OECD Guideline 102 and EU Method A.1. Based on the results of DSC measurements and the capillary method, the test substance melted under decomposition in the temperature range of 250 -271°C. According to REACH Regulation (Annex VII, 7.3, column II), the study on the boiling point does not need to be done for substances which decompose before boiling. In a study conducted according to OECD Guideline 109, EU Method A.3, and DIN 66137-2, the density (at 21.5°C) and the relative density (D21.5/4) of Biofert Plusz were determined to be 1.38 g/cm³ and 1.38, respectively. No experimentally derived test results are available for particle size distribution. According to REACH Regulation (Annex VII, 7.14, column II), a study on granulometry does not need to be conducted if the substance is marketed or used in a non granular or non solid form. Biofert Plusz is marketed and used solely as aqueous solution.

The vapour pressure of Biofert Plusz was investigated in a study conducted according to OECD Guideline 104 and EU Method A.4. The vapour pressure was measured in the temperature range of 21°C to 97°C using the vapour pressure balance (effusion method). Above 52°C a vapour pressure could be measured. Therefore the values for 20 (p=3.5 x 10E-6 hPa), 25 (6.1 x 10E-6 hPa), and 50°C (7.5 x 10E-3) were calculated using the Antoine equation. Due to the inhomogenous consistency of the substance it is reasonable to specify the vapour pressure at 20°C with < 3 x 10E-5 hPa. Since Biofert Plusz is a complex mixture containing organic and inorganic components, a log Kow can not be determined or calculated. The log Kow of the lead component L-threonine is calclulated to be -2.94. The procedure for the determination of the water solubility was adapted to the specific properties of the test substance due to the fact that Biofert Plusz is only partly soluble in water. Both the water soluble and the water insoluble part of the test substance were determined. The water insoluble part of Biofert Plusz was determined to be 133.7 g/kg test substance at 24°C, the part of soluble test substance to 209.2 g/kg TS. The estimated limit concentration, at which precipitation of the former solved components starts was found to be 445 g/kg concentrated filtrate. The pH of an aqueous solution of Biofert Plusz at a concentration of 100 g/L was determined to be 4.3. In a study conducted according to OECD Guideline 115 and EU Method A.5, a surface tension of 45.61 mN/m was determined at a temperature of 20 +/- 0.5°C and a test substance concentration of 1 g/L of the water soluble part of Biofert Plusz. Based on this result (<60 mN/m), the test substance has surface-active properties. According to REACH Regulation (Annex XI, 1.), a study on the flash point does not need to be conducted if based on the available information the substance can be assessed. Biofert Plusz is a solid under standard conditions. The relevant endpoint is therefore the flammability (see below) and not the flash point. The self-ignition temperature of Biofert Plusz was investigated in a study conducted according to EU Method A.16. A self-ignition temperature of Biofert Plusz was not observed up to the maximum applied test temperature of 405°C. The flammability of Biofert Plusz was investigated in a study conducted according to EU Method A.10 (Flammability (Solids)). In the preliminary test the test item could not be ignited with a flame. A main test was therefore not necessary. Based on the result, Biofert Plusz is not a highly flammable solid in the sense of the consolidated version of Council Directive 67/548/EEC Annex V, Method A.10 (Council Directive 92/69/EEC). The pH of an aqueous solution of Biofert Plusz at a concentration of 100 g/L was determined to be 4.3. Based on the available information Biofert Plusz is considered to be a non-explosive substance exhibiting no oxidising properties. According to column 2 of REACH Regulation Annex XI, a study for this endpoint is only required, if the stability in organic solvents is considered to be critical. For an aqueous solution like the UVCB-substance Biofert plusz, this endpoint is neither considered to be critical nor is an experimental study technically feasible. The thermal stability of Biofert Plusz was investigated in a study conducted according to OECD Guideline 113 (Screening Test for Thermal Stability and Stability in Air). The test substance is considered stable at room temperature as no decomposition or chemical transformation was found below 150°C. In accordance with the REACH Regulation (Annex XI, 2.), a study does not need to be done if testing is technically not feasible. The study on viscosity (information requirement section 7.17) cannot be conducted on solid materials or gases. According to ECHA Chapter 7 guidance, viscosity measurement is only relevant to liquids. Biofert Plusz is a solid at standard conditions.