Investigation of OECD 301F ready biodegradability test to evaluate chemical fate in a realistic environment

Metagenomic analysis of ready biodegradability tests to ascertain the relationship between microbiota and the biodegradability of test chemicals

“…Ready biodegradability tests were carried out in accordance with OECD guideline 301C or 301F 1) as follows: Test medium for 301C or 301F was prepared as described by Takekoshi et al 8) where the final concentrations of K In both the 301C and 301F tests, the concentration of the activated sludge (i.e., AS-CERI for the 301C test, or AS-STP for the 301F test) in the test medium was 30 mg L −1 , and the test substance was added to make up a concentration of 100 mg L −1 either directly or after adsorption on silica gel. The procedure for the adsorption of a test substance on silica gel is described by Takekoshi et al, 8) and modifications were made as follows: the test chemical was dissolved not with chloroform but acetone, thoroughly mixed with silica gel, and then acetone was evaporated in a vacuum oven for 14 rather than 28 days. The test medium was stirred and cultivated in darkness at 25± 1°C for 301C, or 22± 1°C for 301F.…”

“…Suzuki et al 7) reported that degradation activity of AS-CERI was decreased by continuous cultivation with glucose and peptone. In addition, Takekoshi et al 8) reported that the biodegradation activities of AS-STP for several test substances were higher than those of AS-CERI. These biodegradation activities were determined based solely on the biodegradation rates of test substances.…”

“…However, the basic reason why the biodegradation activities were different was not fully clarified from the viewpoint of the microbiota since the microbiota of the activated sludge was rarely analyzed. Takekoshi et al 8) found that the biodegradation of a few test chemicals was accelerated just by increasing the medium volume in the condition that the initial concentrations of the test chemical and activated sludge were kept constant. Based on the results, they hypothesized that a large volume of test medium increases the probability of capturing the small minority of microorganisms that play a key role in biodegrading the relevant test chemical.…”

Establishing a ready biodegradability test system using OxiTop^® to evaluate chemical fate in a realistic environment

“…The amount of Tris in the test medium after 28 days was determined by the method described in our previous report 4) ; tetrahydrofuran was added to the medium at a ratio of 2 (tetrahydrofuran) to 3 (test medium), and the supernatant after centrifugation was subjected to HPLC analysis. Spike and recovery tests were carried out in triplicate, and the average recovery percentage was 103± 3%.…”

“…In our previous report, 4) tris(2-ethylhexyl) trimellitate (Tris), which had been determined to be "not readily biodegradable" under the CSCL, 5) was subjected to ready biodegradability tests under various conditions, and the amounts of Tris were determined using HPLC after 28 days of exposure. While Tris was not degraded at all in the 301C test with the standard activated sludge, 3% of Tris was degraded in the 301F test using the activated sludge obtained from a municipal sewage treatment plant without any cultivation.…”